diff options
Diffstat (limited to 'libXdmcp/doc')
| -rw-r--r-- | libXdmcp/doc/xdmcp.xml | 7813 |
1 files changed, 3907 insertions, 3906 deletions
diff --git a/libXdmcp/doc/xdmcp.xml b/libXdmcp/doc/xdmcp.xml index c8797742d..36abb75a9 100644 --- a/libXdmcp/doc/xdmcp.xml +++ b/libXdmcp/doc/xdmcp.xml @@ -1,3906 +1,3907 @@ -<?xml version="1.0" encoding="UTF-8" ?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
- "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
-<!--
- variable names used in equation markup in the authentication chapter
- FIXME: Replace with mathml?
- -->
-<!ENTITY variable.D "<emphasis role='italic'>D</emphasis>">
-<!ENTITY variable.N "<emphasis role='italic'>N</emphasis>">
-<!ENTITY variable.T "<emphasis role='italic'>T</emphasis>">
-<!ENTITY variable.Delta "<emphasis role='italic'>Δ</emphasis>">
-<!ENTITY variable.alpha "<emphasis role='italic'>α</emphasis>">
-<!ENTITY variable.beta "<emphasis role='italic'>β</emphasis>">
-<!ENTITY variable.kappa "<emphasis role='italic'>κ</emphasis>">
-<!ENTITY variable.rho "<emphasis role='italic'>ρ</emphasis>">
-<!ENTITY variable.sigma "<emphasis role='italic'>σ</emphasis>">
-<!ENTITY variable.tau "<emphasis role='italic'>τ</emphasis>">
-]>
-
-<book id="xdmcp">
-
-<bookinfo>
- <title>X Display Manager Control Protocol</title>
- <subtitle>X.Org Standard</subtitle>
- <releaseinfo>Version 1.1</releaseinfo>
- <authorgroup>
- <author>
- <firstname>Keith</firstname><surname>Packard</surname>
- <affiliation><orgname>
-X Consortium,
-Laboratory for Computer Science,
-Massachusetts Institute of Technology
- </orgname></affiliation>
- </author>
- </authorgroup>
-
- <copyright><year>1989</year><year>2004</year>
- <holder>The Open Group</holder></copyright>
- <productnumber>X Version 11, Release 6.8</productnumber>
-
-<legalnotice>
-
-
-
-<para>
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-</para>
-<para>
-The above copyright notice and this permission notice shall be included in
-all copies or substantial portions of the Software.
-</para>
-<para>
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
-AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
-CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-</para>
-<para>
-Except as contained in this notice, the name of The Open Group shall not be
-used in advertising or otherwise to promote the sale, use or other dealings
-in this Software without prior written authorization from The Open Group.
-</para>
-
-<para>
-<emphasis remap='I'>X Window System</emphasis> is a trademark of The Open Group.
-</para>
-</legalnotice>
-</bookinfo>
-
-<chapter id="Purpose_and_Goals">
-<title>Purpose and Goals</title>
-<!-- .XS -->
-<!-- (SN Purpose and Goals -->
-<!-- .XE -->
-<para>
-<!-- .LP -->
-The purpose of the X Display Manager Control Protocol (XDMCP)
-is to provide a uniform mechanism for an autonomous
-display to request login service from a remote host.
-By autonomous, we mean
-the display consists of hardware and processes that are independent of any
-particular host where login service is desired. (For example, the server
-cannot simply be started by a
-<function>fork/exec</function>
-sequence on the host.)
-An X terminal (screen, keyboard, mouse, processor, network interface)
-is a prime example of an autonomous display.
-</para>
-
-<para>
-From the point of view of the end user, it is very important to make
-autonomous displays as easy to use as traditional hardwired character
-terminals. Specifically, you can typically just power on a hardwired
-terminal and be greeted with a login prompt. The same should be possible
-with autonomous displays. However, in a network environment with multiple
-hosts, the end user may want to choose which host(s) to connect to. In an
-environment with many displays and many hosts, a site administrator may want
-to associate particular collections of hosts with particular displays. We
-would like to support the following options:
-</para>
-
-<itemizedlist>
- <listitem>
- <para>
-The display has a single, fixed host to which it should connect. It should be
-possible to power on the display and receive a login prompt, without user
-intervention.
- </para>
- </listitem>
- <listitem>
- <para>
-Any one of several hosts on a network or subnetwork may be acceptable
-for accepting login from the display.
-(For example, the user's file systems can be mounted onto
-any such host, providing comparable environments.) It should be possible
-for the display to broadcast to find such hosts and to have the display
-either automatically choose a host or present the possible hosts to the
-user for selection.
- </para>
- </listitem>
- <listitem>
- <para>
-The display has a fixed set of hosts that it can connect to. It should be
-possible for the display to have that set stored in RAM, but it should also be
-possible for a site administrator to be able to maintain host sets for a
-large number of displays using a centralized facility, without having to
-interact (physically or electronically) with each individual display.
-Particular hosts should be allowed to refuse login service, based on
-whatever local criteria are desired.
- </para>
- </listitem>
-</itemizedlist>
-
-<para>
-The control protocol should be designed in such a way that it can be used over
-a reasonable variety of communication transport layers. In fact, it is quite
-desirable if every major network protocol family that supports the standard X
-protocol is also capable of supporting XDMCP, because the end result of XDMCP
-negotiation will be standard X protocol connections to the display.
-However, because the number of displays per host may be large,
-a connection-based protocol appears less desirable
-than a connection-less protocol. For this reason the protocol is designed
-to use datagram services with the display responsible for sequencing and
-retransmission.
-</para>
-<para>
-<!-- .LP -->
-To keep the burden on displays at a minimum (because display cost is not
-a factor that can be ignored), it is desirable that displays not be required
-to maintain permanent state (across power cycles) for the purposes
-of the control protocol,
-and it is desirable to keep required state at a minimum while the
-display is powered on.
-</para>
-<para>
-<!-- .LP -->
-Security is an important consideration and must be an integral part of the
-design. The important security goals in the context of XDMCP are:
-</para>
-<itemizedlist>
- <listitem>
- <para>
-It should be possible for the display to verify that it is communicating
-with a legitimate host login service. Because the user will present
-credentials (for example, password) to this service,
-it is important to avoid spoof attacks.
- </para>
- </listitem>
- <listitem>
- <para>
-It should be possible for the display and the login service to negotiate the
-authorization mechanism to be used for the standard X protocol.
- </para>
- </listitem>
- <listitem>
- <para>
-It should be possible to provide the same level of security in verifying the
-login service as is provided by the negotiated authorization mechanism.
- </para>
- </listitem>
- <listitem>
- <para>
-Because there are no firm standards yet in the area of security,
-XDMCP must be flexible enough to accomodate a variety of security mechanisms.
- </para>
- </listitem>
-</itemizedlist>
-</chapter>
-
-<chapter id="Overview_of_the_Protocol">
-<title>Overview of the Protocol</title>
-<!-- .XS -->
-<!-- (SN Overview of the Protocol -->
-<!-- .XE -->
-<para>
-<!-- .LP -->
-XDMCP is designed to provide authenticated access to display management
-services for remote displays. A new network server, called a \fIDisplay
-Manager\fP, will use XDMCP to communicate with displays to negotiate the
-startup of X sessions. The protocol allows the display to authenticate the
-manager. It also allows most of the configuration information to be
-centralized with the manager and to ease the burden of system administration
-in a large network of displays.
-The essential goal is to provide plug-and-play
-services similar to those provided in the familiar mainframe/terminal world.
-</para>
-<para>
-<!-- .LP -->
-Displays may be turned off by the user at any time. Any existing session
-running on a display that has been turned off must be identifiable. This
-is made possible by requiring a three-way handshake to start a session. If
-the handshake succeeds, any existing session is terminated immediately and a
-new session started. There is the problem (at least with TCP) that
-connections may not be closed when the display is turned off. In most
-environments, the manager should reduce this problem by periodically XSync'ing
-on its own connection, perhaps every five to ten minutes, and terminating the
-session if its own connection ever closes.
-</para>
-<para>
-<!-- .LP -->
-Displays should not be required to retain permanent state for purposes of
-the control protocol. One solution to packets received out of sequence
-would be to use monotonically increasing message identifiers in each message
-to allow both sides to ignore messages that arrive out-of-sequence. For
-this to work, displays would at a minimum have to increment a stable crash
-count each time they are powered on and use that number as part of a
-larger sequence number. But if displays cannot retain permanent state this
-cannot work. Instead, the manager assumes the responsibility for permanent
-state by generating unique numbers that identify a particular session and
-the protocol simply ignores packets that correspond to an invalid session.
-</para>
-<para>
-<!-- .LP -->
-The Manager must not be responsible for packet reception. To prevent the
-Manager from becoming stuck because of a hostile display, no portion of the
-protocol requires the Manager to retransmit a packet. Part of this means
-that any valid packet that the Manager does receive must be
-acknowledged in some way to prevent the display from continuously resending
-packets. The display can keep the protocol running as it will always know
-when the Manager has received (at least one copy of) a packet. On the
-Manager side, this means that any packet may be received more than once (if
-the response was lost) and duplicates must be ignored.
-</para>
-</chapter>
-
-<chapter id="Data_Types">
-<title>Data Types</title>
-<!-- .XS -->
-<!-- (SN Data Types -->
-<!-- .XE -->
-<para>
-<!-- .LP -->
-XDMCP packets contain several types of data. Integer values are always
-stored most significant byte first in the packet ("Big Endian" order).
-As XDMCP will not be used to transport large quantities of data, this
-restriction will not substantially hamper the efficiency of any
-implementation. Also, no padding of any sort will occur within the packets.
-</para>
-
-<informaltable frame="none">
- <tgroup cols='3' align='left'>
- <colspec colname='c1' colsep="0"/>
- <colspec colname='c2' colsep="0"/>
- <colspec colname='c3' colsep="0"/>
- <thead>
- <row>
- <entry>Type Name</entry>
- <entry>Length (Bytes)</entry>
- <entry>Description</entry>
- </row>
- </thead>
- <tbody>
- <row rowsep="0">
- <entry>CARD8</entry>
- <entry>1</entry>
- <entry>A single byte unsigned integer</entry>
- </row>
- <row rowsep="0">
- <entry>CARD16</entry>
- <entry>2</entry>
- <entry>Two byte unsigned integer</entry>
- </row>
- <row rowsep="0">
- <entry>CARD32</entry>
- <entry>4</entry>
- <entry>Four byte unsigned integer</entry>
- </row>
- <row rowsep="0">
- <entry>ARRAY8</entry>
- <entry>n+2</entry>
- <entry>
-This is actually a CARD16 followed by
-a collection of CARD8. The value of the CARD16
-field (n) specifies the number of CARD8 values to follow
- </entry>
- </row>
- <row rowsep="0">
- <entry>ARRAY16</entry>
- <entry>2*m+1</entry>
- <entry>
-This is a CARD8 (m) which specifies the
-number of CARD16 values to follow
- </entry>
- </row>
- <row rowsep="0">
- <entry>ARRAY32</entry>
- <entry>4*l+1</entry>
- <entry>
-This is a CARD8 (l) which specifies the
-number of CARD32 values to follow
- </entry>
- </row>
- <row rowsep="0">
- <entry>ARRAYofARRAY8</entry>
- <entry>?</entry>
- <entry>
-This is a CARD8 which specifies the
-number of ARRAY8 values to follow.
- </entry>
- </row>
- </tbody>
- </tgroup>
-</informaltable>
-</chapter>
-
-<chapter id="Packet_Format">
-<title>Packet Format</title>
-<!-- .XS -->
-<!-- (SN Packet Format -->
-<!-- .XE -->
-<para>
-All XDMCP packets have the following information:
-</para>
-
-<informaltable frame="none">
- <tgroup cols='3' align='left'>
- <colspec colname='c1' colsep="0"/>
- <colspec colname='c2' colsep="0"/>
- <colspec colname='c3' colsep="0"/>
- <thead>
- <row>
- <entry>Length (Bytes)</entry>
- <entry>Field Type</entry>
- <entry>Description</entry>
- </row>
- </thead>
- <tbody>
- <row rowsep="0">
- <entry>2</entry>
- <entry>CARD16</entry>
- <entry>version number</entry>
- </row>
- <row rowsep="0">
- <entry>2</entry>
- <entry>CARD16</entry>
- <entry>opcode packet header</entry>
- </row>
- <row rowsep="0">
- <entry>2</entry>
- <entry>CARD16</entry>
- <entry>n = length of remaining data in bytes</entry>
- </row>
- <row rowsep="0">
- <entry>n</entry>
- <entry>???</entry>
- <entry>packet-specific data</entry>
- </row>
- </tbody>
- </tgroup>
-</informaltable>
-
-<para>
-<!-- .LP -->
-The fields are as follows:
-</para>
-
-<variablelist>
- <varlistentry>
- <term>Version number</term>
- <listitem>
- <para>
-This specifies the version of XDMCP that generated this packet in
-case changes in this protocol are required. Displays and
-managers may choose to support older versions for compatibility.
-This field will initially be one (1).
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>Opcode</term>
- <listitem>
- <para>
-This specifies what step of the protocol this packet represents and should
-contain one of the following values (encoding provided in section below):
-<emphasis role="bold">BroadcastQuery</emphasis>,
-<emphasis role="bold">Query</emphasis>,
-<emphasis role="bold">IndirectQuery</emphasis>,
-<emphasis role="bold">ForwardQuery</emphasis>,
-<emphasis role="bold">Willing</emphasis>,
-<emphasis role="bold">Unwilling</emphasis>,
-<emphasis role="bold">Request</emphasis>,
-<emphasis role="bold">Accept</emphasis>,
-<emphasis role="bold">Decline</emphasis>,
-<emphasis role="bold">Manage</emphasis>,
-<emphasis role="bold">Refuse</emphasis>,
-<emphasis role="bold">Failed</emphasis>,
-<emphasis role="bold">KeepAlive</emphasis>
-or
-<emphasis role="bold">Alive</emphasis>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>Length of data in bytes</term>
- <listitem>
- <para>
-This specifies the length of the information following the first 6 bytes.
-Each packet-type has a different format and will need to be separately
-length-checked against this value. Because every data item has either an
-explicit or implicit length, this can be easily accomplished.
-Packets that have too little or too much data should be ignored.
- </para>
- </listitem>
- </varlistentry>
-</variablelist>
-<para>
-Packets should be checked to make sure that they satisfy the following
-conditions:
-</para>
-
-<orderedlist>
- <listitem>
- <para>
-They must contain valid opcodes.
- </para>
- </listitem>
- <listitem>
- <para>
-The length of the remaining data should correspond to the sum of the
-lengths of the individual remaining data items.
- </para>
- </listitem>
- <listitem>
- <para>
-The opcode should be expected (a finite state diagram is given
-in a later section).
- </para>
- </listitem>
- <listitem>
- <para>
-If the packet is of type
-<emphasis role="bold">Manage</emphasis> or
-<emphasis role="bold">Refuse</emphasis>,
-the Session ID should match the value sent in the preceding
-<emphasis role="bold">Accept</emphasis> packet.
- </para>
- </listitem>
-</orderedlist>
-</chapter>
-
-<chapter id="Protocol">
-<title>Protocol</title>
-<!-- .XS -->
-<!-- (SN Protocol -->
-<!-- .XE -->
-<para>
-Each of the opcodes is described below. Because a given packet type is only
-ever sent one way, each packet description below indicates the direction.
-Most of the packets have additional information included beyond the
-description above. The additional information is appended to the packet
-header in the order described without padding, and the length field is
-computed accordingly.
-</para>
-
-<informaltable frame="none">
- <tgroup cols='10' align='left'>
- <colspec colname='col1' colsep="0" colwidth="1*"/>
- <colspec colname='col2' colsep="0" colwidth="1*"/>
- <colspec colname='col3' colsep="0" colwidth="1*"/>
- <colspec colname='col4' colsep="0" colwidth="1*"/>
- <colspec colname='col5' colsep="0" colwidth="1*"/>
- <colspec colname='col6' colsep="0" colwidth="1*"/>
- <colspec colname='col7' colsep="0" colwidth="1*"/>
- <colspec colname='col8' colsep="0" colwidth="1*"/>
- <colspec colname='col9' colsep="0" colwidth="1*"/>
- <colspec colname='col10' colsep="0" colwidth="1*"/>
- <spanspec namest="col1" nameend="col10" spanname="col1_on" align="left"/>
- <spanspec namest="col2" nameend="col10" spanname="col2_on" align="left"/>
- <spanspec namest="col3" nameend="col10" spanname="col3_on" align="left"/>
- <spanspec namest="col4" nameend="col10" spanname="col4_on" align="left"/>
- <spanspec namest="col5" nameend="col10" spanname="col5_on" align="left"/>
- <tbody>
- <row rowsep="0">
- <entry spanname="col1_on"><emphasis role="bold">Query</emphasis></entry>
- </row>
- <row rowsep="0">
- <entry spanname="col1_on"><emphasis role="bold">BroadcastQuery</emphasis></entry>
- </row>
- <row rowsep="0">
- <entry spanname="col1_on"><emphasis role="bold">IndirectQuery</emphasis></entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">Display -> Manager</entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">Additional Fields:</entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis>Authentication Names</emphasis>: ARRAYofARRAY8
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Specifies a list of authentication names that the display supports. The
-manager will choose one of these and return it in the
-<emphasis role="bold">Willing</emphasis> packet.
- </entry>
- </row>
-<!-- AAAAAAAAAAAAA -->
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry>Semantics</entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-<para>
-A <function>Query</function>
-packet is sent from the display to a specific host to ask if
-that host is willing to provide management services to this display. The
-host should respond with
-<function>Willing</function>
-if it is willing to service the display or
-<function>Unwilling</function>
-if it is not.
-</para>
-
-<para>
-A
-<function>BroadcastQuery</function>
-packet is similar to the
-<function>Query</function>
-packet except that it is intended to be received by all hosts on the network
-(or subnetwork). However, unlike
-<function>Query</function>
-requests, hosts that are not willing to service the display
-should simply ignore
-<function>BroadcastQuery</function>
-requests.
-</para>
-
-<para>
-An
-<function>IndirectQuery</function>
-packet is sent to a well known manager that forwards
-the request to a larger collection of secondary managers using
-<function>ForwardQuery</function>
-packets.
-In this way, the collection of managers that respond can be grouped
-on other than network boundaries; the use of a central manager reduces
-system administrative overhead.
-The primary manager may also send a
-<function>Willing</function>
-packet in response to this packet.
-</para>
-
-<para>
-Each packet type has slightly different semantics:
-</para>
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-<para>
-The
-<function>Query</function>
-packet is destined only for a single host.
-If the display is instructed to
-<function>Query</function>
-multiple managers, it will send multiple
-<function>Query</function>
-packets. The
-<function>Query</function>
-packet also demands a response from the manager, either
-<function>Willing</function>
-or
-<function>Unwilling</function>.
- </para>
- <para>
-The
-<function>BroadcastQuery</function>
-packet is sent to many hosts.
-Each manager that receives this packet will not respond with an
-<function>Unwilling</function>
-packet.
- </para>
- <para>
-The
-<function>IndirectQuery</function>
-packet is sent to only one manager with the request
-that the request be forwarded to a larger list of managers using
-<function>ForwardQuery</function>
-packets. This list is expected to be maintained at one
-central site to reduce administrative overhead.
-The function of this packet type is similar to
-<function>BroadcastQuery except that</function>
-<function>BroadcastQuery</function>
-is not forwarded.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">Valid Responses:</entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<function>Willing</function>,
-<function>Unwilling</function>
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">Problems/Solutions:</entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">Problem:</entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-<para>Not all managers receive the query packet.</para>
-<para>Indication:</para>
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-None if
-<function>BroadcastQuery</function>
-or
-<function>IndirectQuery</function>
-was sent, else failure to receive
-<function>Willing</function>.
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">Solution:</entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Repeatedly send the packet while waiting for user to choose a manager.
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Timeout/Retransmission policy:
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-An exponential backoff algorithm should be used here to reduce network load
-for long-standing idle displays. Start at 2 seconds, back off by factors of
-2 to 32 seconds, and discontinue retransmit after 126 seconds. The display
-should reset the timeout when user-input is detected. In this way, the
-display will wakeup when touched by the user.
- </entry>
- </row>
- <row rowsep="0">
- <entry spanname="col1_on">
-<function>ForwardQuery</function>
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-<para>Primary Manager -> Secondary Manager</para>
-<para>Additional Fields:</para>
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Client Address</emphasis>: ARRAY8
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Specifies the network address of the client display.
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Client Port</emphasis>: ARRAY8
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Specifies an identification of the client task on the client display.
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Authentication Names</emphasis>: ARRAYofARRAY8
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Is a duplicate of Authentication Names array that was received
-in the
-<function>IndirectQuery</function>
-packet.
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Semantics:
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
- <para>
-When primary manager receives a
-<function>IndirectQuery</function>
-packet, it is responsible for sending
-<function>ForwardQuery</function>
-packets to an appropriate list of
-managers that can provide service to the display using the same network
-type as the one the original
-<function>IndirectQuery</function>
-packet was received from.
-The Client Address and Client Port fields must contain an
-address that the secondary manager can use to reach the display also using
-this same network. Each secondary manager sends a
-<function>Willing</function>
-packet to the display if it is willing to provide service.
- </para>
-
- <para>
-<function>ForwardQuery</function>
-packets are similar to
-<function>BroadcastQuery</function>
-packets in that managers that are not willing to service
-particular displays should not send a
-<function>Unwilling</function>
-packet.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Valid Responses:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<function>Willing</function>
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Problems/Solutions:
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Identical to
-<function>BroadcastQuery</function>
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Timeout/Retransmission policy:
- </entry>
- </row>
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Like all packets sent from a manager, this packet should never be
-retransmitted.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry spanname="col1_on">
-<function>Willing</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
- <para>
-Manager -> Display
- </para>
- <para>
-Additional Fields:
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Authentication Name</emphasis>: ARRAY8
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-<para>
-Specifies the authentication method, selected from the list offered in the
-<function>Query ,</function>
-<function>BroadcastQuery ,</function>
-or
-<function>IndirectQuery</function>
-packet that the manger expects the display to use in the subsequent
-<function>Request</function>
-packet.
-This choice should remain as constant as feasible so that displays that
-send multiple
-<function>Query</function>
-packets can use the Authentication Name from any
-<function>Willing</function>
-packet that arrives.
-</para>
-<para>
-The display is free to ignore managers that request an insufficient level
-of authentication.
-</para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Hostname</emphasis>: ARRAY8
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Is a human readable string describing the host from which the packet was sent.
-The protocol specifies no interpretation of the data in this field.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Status</emphasis>: ARRAY8
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Is a human readable string describing the status of the host. This could
-include load average/number of users connected or other information. The
-protocol specifies no interpretation of the data in this field.
- </entry>
- </row>
-
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Semantics:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-A
-<function>Willing</function>
-packet is sent by managers that may service connections from
-this display. It is sent in response to either a
-<function>Query ,</function>
-<function>BroadcastQuery ,</function>
-or
-<function>ForwardQuery</function>
-but does not imply a commitment to provide service
-(for example, it may later decide that it has accepted enough
-connections already).
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Problems/Solutions:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Problem:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-<para>
-<function>Willing</function>
-not received by the display.
-</para>
-<para>
-Indication:
-</para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-None if
-<function>BroadcastQuery</function>
-or
-<function>IndirectQuery</function>
-was sent, else failure to receive
-<function>Willing .</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-The display should continue to send the query until a response is received.
- </entry>
- </row>
-
-
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Timeout/Retransmission policy:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Like all packets sent from the manager to the display, this packet should
-never be retransmitted.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry spanname="col1_on">
-<function>Unwilling</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
- <para>
-Manager -> Display
- </para>
- <para>
-Additional Fields:
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-The Hostname and Status fields as in the
-<function>Willing</function>
-packet.
-The Status field should indicate to the user a reason
-for the refusal of service.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Semantics:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-An
-<function>Unwilling</function>
-packet is sent by managers in response to direct
-<function>Query</function>
-requests (as opposed to
-<function>BroadcastQuery</function>
-or
-<function>IndirectQuery</function>
-requests) if the manager will not accept requests for management.
-This is typically sent by managers that wish to only service
-particular displays or that handle a limited number of displays at once.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Problems/Solutions:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Problem:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-<para>
-<function>Unwilling</function>
-not received by the display.
-</para>
-<para>
-Indication:
-</para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Display fails to receive
-<function>Unwilling .</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-The display should continue to send
-<function>Query</function>
-messages until a response is received.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Timeout/Retransmission policy:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Like all packets sent from the manager to the display, this packet should
-never be retransmitted.
- </entry>
- </row>
- <row rowsep="0">
- <entry spanname="col1_on">
-<function>Request</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
- <para>
-Display -> Manager
- </para>
- <para>
-Additional Fields:
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Display Number</emphasis>: CARD16
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Specifies the index of this particular server for the host
-on which the display is resident.
-This value will be zero for most autonomous displays.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Connection Types</emphasis>: ARRAY16
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Specifies an array indicating the stream services accepted by the display.
-If the high-order byte in a particular entry is zero, the low-order byte
-corresponds to an X-protocol host family type.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Connection Addresses</emphasis>: ARRAYofARRAY8
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-For each connection type in the previous array, the corresponding entry in
-this array indicates the network address of the display device.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
- <para>
-<emphasis remap='I'>Authentication Name</emphasis>: ARRAY8
- </para>
- <para>
-<emphasis remap='I'>Authentication Data</emphasis>: ARRAY8
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Specifies the authentication protocol that the display expects
-the manager to validate itself with. The Authentication Data is
-expected to contain data that the manager will interpret, modify
-and use to authenticate itself.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Authorization Names</emphasis>: ARRAYofARRAY8
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Specifies which types of authorization the display supports. The
-manager may decide to reject displays with which it cannot perform
-authorization.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Manufacturer Display ID</emphasis>: ARRAY8
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Can be used by the manager to determine how to decrypt the
-Authentication Data field in this packet. See the section below on
-Manufacturer Display ID Format.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Semantics:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-A
-<function>Request</function>
-packet is sent by a display to a specific host to request a
-session ID in preparation for a establishing a connection. If the manager
-is willing to service a connection to this display, it should return an
-<function>Accept</function>
-packet with a valid session ID and should be ready for a subsequent
-<function>Manage</function>
-request. Otherwise, it should return a
-<function>Decline</function>
-packet.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Valid Responses:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<function>Accept ,</function>
-<function>Decline</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Problems/Solutions:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Problem:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Request not received by manager.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Indication:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Display timeout waiting for response.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Display resends
-<function>Request</function>
-message.
- </entry>
- </row>
-
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Problem:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Message received out of order by manager.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Indication:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-None.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Each time a
-<function>Request</function>
-is sent, the manager sends the Session ID
-associated with the next session in the
-<function>Accept .</function>
-If that next session is not yet started,
-the manager will simply resend with the same Session ID.
-If the session is in progress, the manager will reply
-with a new Session ID; in which case, the
-<function>Accept</function>
-will be discarded by the display.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Timeout/Retransmission policy:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Timeout after 2 seconds, exponential backoff to 32 seconds.
-After no more than 126 seconds, give up and report an error to the user.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry spanname="col1_on">
-<function>Accept</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
- <para>
-Manager -> Display
- </para>
- <para>
-Additional Fields:
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Session ID</emphasis>: CARD32
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Identifies the session that can be started by the manager.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
- <para>
-<emphasis remap='I'>Authentication Name</emphasis>: ARRAY8
- </para>
- <para>
-<emphasis remap='I'>Authentication Data</emphasis>: ARRAY8
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Is the data sent back to the display to authenticate the manager.
-If the Authentication Data is not the value expected by the display, it
-should terminate the protocol at this point and display an error to the user.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
- <para>
-<emphasis remap='I'>Authorization Name</emphasis>: ARRAY8
- </para>
- <para>
-<emphasis remap='I'>Authorization Data</emphasis>: ARRAY8
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Is the data sent to the display to indicate the type of authorization the
-manager will be using in the first call to
-<function>XOpenDisplay</function>
-after the
-<function>Manage</function>
-packet is received.
- </entry>
- </row>
-
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Semantics:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<para>
-An
-<function>Accept</function>
-packet is sent by a manager in response to a
-<function>Request</function>
-packet if the manager is willing to establish a connection for the display.
-The Session ID is used to identify this connection from any preceding
-ones and will be used by the display in its subsequent
-<function>Manage</function>
-packet.
-The Session ID is a 32-bit number that is incremented each time an
-<function>Accept</function>
-packet is sent as it must be unique over a reasonably long period of time.
-</para>
-<para>
-If the authentication information is invalid, a
-<function>Decline</function>
-packet will be returned with an appropriate
-<function>Status</function>
-message.
-</para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Problems/Solutions:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Problem:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-<function>Accept</function>
-or
-<function>Decline</function>
-not received by display.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Indication:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Display timeout waiting for response to
-<function>Request .</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Display resends
-<function>Request</function>
-message.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Problem:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Message received out of order by display.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Indication:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Display receives
-<function>Accept</function>
-after
-<function>Manage</function>
-has been sent.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Display discards
-<function>Accept</function>
-messages after it has sent a
-<function>Manage</function>
-message.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Timeout/Retransmission policy:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Like all packets sent from the manager to the display, this packet should
-never be retransmitted.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry spanname="col1_on">
-<function>Decline</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
- <para>
-Manager -> Display
- </para>
- <para>
-Additional Fields:
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Status</emphasis>: ARRAY8
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Is a human readable string indicating the reason for refusal of
-service.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
- <para>
-<emphasis remap='I'>Authentication Name</emphasis>:
-ARRAY8
- </para>
- <para>
-<emphasis remap='I'>Authentication Data</emphasis>:
-ARRAY8
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Is the data sent back to the display to authenticate the manager. If the
-Authentication Data is not the value expected by the display, it
-should terminate the protocol at this point and display an error to the user.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Semantics:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-A
-<function>Decline</function>
-packet is sent by a manager in response to a
-<function>Request</function>
-packet if the manager is unwilling to establish a connection for the
-display.
-This is allowed even if the manager had responded
-<function>Willing</function>
-to a previous query.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Problems/Solutions:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Same as for
-<function>Accept .</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Timeout/Retransmission policy:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Like all packets sent from a manager to a display, this packet should never
-be retransmitted.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry spanname="col1_on">
-<function>Manage</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
- <para>
-Display -> Manager
- </para>
- <para>
-Additional Fields:
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Session ID</emphasis>: CARD32
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Should contain the nonzero session ID returned in the
-<function>Accept</function>
-packet.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Display Number</emphasis>: CARD16
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Must match the value sent in the previous
-<function>Request</function>
-packet.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Display Class</emphasis>: ARRAY8
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Specifies the class of the display.
-See the Display Class Format section,
-which discusses the format of this field.
- </entry>
- </row>
-
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Semantics:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-A
-<function>Manage</function>
-packet is sent by a display to ask the manager to begin a
-session on the display. If the Session ID is correct the manager
-should open a connection; otherwise, it should respond with a
-<function>Refuse</function>
-or
-<function>Failed</function>
-packet, unless the Session ID matches a currently
-running session or a session that has not yet successfully opened the
-display but has not given up the attempt. In this latter case, the
-<function>Manage</function>
-packet should be ignored.
-This will work as stream connections give positive success indication
-to both halves of the stream, and positive failure indication
-to the connection initiator (which will eventually generate a
-<function>Failed</function>
-packet).
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Valid Responses:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-X connection with correct auth info,
-<function>Refuse ,</function>
-<function>Failed .</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Problems/Solutions:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Problem:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-<function>Manage</function>
-not received by manager.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Indication:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Display timeout waiting for response.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Display resends
-<function>Manage</function>
-message.
- </entry>
- </row>
-
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Problem:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-<function>Manage</function>
-received out of order by manager.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Indication:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Session already in progress with matching Session ID.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-<function>Manage</function>
-packet ignored.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Indication:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Session ID does not match next Session ID.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-<function>Refuse</function>
-message is sent.
- </entry>
- </row>
-
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Problem:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Display cannot be opened on selected stream.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Indication:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Display connection setup fails.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-<function>Failed</function>
-message is sent including a human readable reason.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Problem:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Display open does not succeed before a second manage packet is received
-because of a timeout occuring in the display.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Indication:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-<function>Manage</function>
-packet received with Session ID matching the session
-attempting to connect to the display.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-<function>Manage</function>
-packet is ignored. As the stream connection will either
-succeed, which will result in an active session, or the stream will
-eventually give up hope of connecting and send a
-<function>Failed</function>
-packet; no response to this
-<function>Manage</function>
-packet is necessary.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Timeout/Retransmission policy:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Timeout after 2 seconds, exponential backoff to 32 seconds. After no more
-than 126 seconds, give up and report an error to the user.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry spanname="col1_on">
-<function>Refuse</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
- <para>
-Manager -> Display
- </para>
- <para>
-Additional Fields:
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Session ID</emphasis>: CARD32
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Should be set to the Session ID received in the
-<function>Manage</function>
-packet.
- </entry>
- </row>
-
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Semantics:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-A
-<function>Refuse</function>
-packet is sent by a manager when the Session ID received in the
-<function>Manage</function>
-packet does not match the current Session ID.
-The display should assume that it received an old
-<function>Accept</function>
-packet and should resend its
-<function>Request</function>
-packet.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Problems/Solutions:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Problem:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Error message is lost.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Indication:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Display times out waiting for
-new connection,
-<function>Refuse</function>
-or
-<function>Failed .</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Display resends
-<function>Manage</function>
-message.
- </entry>
- </row>
-
-
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Timeout/Retransmission policy:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Like all packets sent from a manager to a display, this packet should never be
-retransmitted.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry spanname="col1_on">
-<function>Failed</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
- <para>
-Manager -> Display
- </para>
- <para>
-Additional Fields:
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Session ID</emphasis>: CARD32
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Should be set to the Session ID received in the
-<function>Manage</function>
-packet.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Status</emphasis>: ARRAY8
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Is a human readable string indicating the reason for failure.
- </entry>
- </row>
-
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Semantics:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-A
-<function>Failed</function>
-packet is sent by a manager when it has problems establishing
-the initial X connection in response to the
-<function>Manage</function>
-packet.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Problems/Solutions
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Same as for
-<function>Refuse .</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry spanname="col1_on">
-<function>KeepAlive</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
- <para>
-Display -> Manager
- </para>
- <para>
-Additional Fields:
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Display Number</emphasis>: CARD16
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Set to the display index for the display host.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Session ID</emphasis>: CARD32
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Should be set to the Session ID received in the
-<function>Manage</function>
-packet during the negotiation for the current session.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Sematics:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
- <para>
-A
-<function>KeepAlive</function>
-packet can be sent at any time during the session by a
-display to discover if the manager is running.
-The manager should respond with
-<function>Alive</function>
-whenever it receives this type of packet.
- </para>
- <para>
-This allows the display to discover when the manager host
-is no longer running.
-A display is not required to send
-<function>KeepAlive</function>
-packets and, upon lack of receipt of
-<function>Alive</function>
-packets, is not required to perform any specific action.
- </para>
- <para>
-The expected use of this packet is to terminate an active session when the
-manager host or network link fails. The display should keep track of the
-time since any packet has been received from the manager host and use
-<function>KeepAlive</function>
-packets when a substantial time has elapsed since the
-most recent packet.
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Valid Responses:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<function>Alive</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Problems/Solutions:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-Problem:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Manager does not receive the packet or display does not receive the response.
- </entry>
- </row>
-
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Indication:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-No
-<function>Alive</function>
-packet is returned.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Solution:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col5_on">
-Retransmit the packet with an exponential backoff; start at 2 seconds and
-assume the host is not up after no less than 30 seconds.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry spanname="col1_on">
-<function>Alive</function>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
- <para>
-Manager -> Display
- </para>
- <para>
-Additional Fields:
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Session Running</emphasis>: CARD8
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Indicates that the session identified by Session ID is
-currently active. The value is zero if no session is active
-or one if a session
-is active.
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-<emphasis remap='I'>Session ID</emphasis>: CARD32
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry></entry>
- <entry spanname="col4_on">
-Specifies the ID of the currently running session; if any.
-When no session is active this field should be zero.
- </entry>
- </row>
-
-
- <row rowsep="0">
- <entry></entry>
- <entry spanname="col2_on">
-Semantics:
- </entry>
- </row>
-
- <row rowsep="0">
- <entry></entry>
- <entry></entry>
- <entry spanname="col3_on">
-An
-<function>Alive</function>
-packet is sent in response to a
-<function>KeepAlive</function>
-request.
-If a session is currently active on the display, the manager includes the
-Session ID in the packet. The display can use this information to
-determine the status of the manager.
- </entry>
- </row>
- </tbody>
- </tgroup>
-</informaltable>
-
-</chapter>
-
-<chapter id="Session_Termination">
-<title>Session Termination</title>
-<para>
-When the session is over, the initial connection with the display (the one
-that acknowledges the
-<function>Manage</function>
-packet) will be closed by the manager.
-If only a single session was active on the display,
-all other connections should be closed by the display
-and the display should be reset. If multiple sessions
-are active simultaneously and the display can identify which connections
-belong to the terminated sesssion, those connections should be closed.
-Otherwise, all connections should be closed and the display reset only when
-all sessions have been terminated (that is, all initial connections closed).
-</para>
-
-<para>
-The session may also be terminated at any time by the display if the
-managing host no longer responds to
-<function>KeepAlive</function>
-packets.
-The exact time-outs for sending
-<function>KeepAlive</function>
-packets is not specified in this protocol as the trade off
-should not be fixed between loading an otherwise idle system with spurious
-<function>KeepAlive</function>
-packets and not noticing that the manager host is down for a long time.
-</para>
-</chapter>
-
-<chapter id="State_Diagrams">
-<title>State Diagrams</title>
-<!-- .XS -->
-<!-- (SN State Diagrams -->
-<!-- .XE -->
-<para>
-<!-- .LP -->
-The following state diagrams are designed to cover all actions of both
-the display and the manager. Any packet that is received out-of-sequence
-will be ignored.
-</para>
-<para>
-<!-- .LP -->
-Display:
-</para>
-
-<variablelist>
- <varlistentry>
- <term><emphasis remap='I'>start</emphasis>:</term>
- <listitem>
- <para>
-User-requested connect to one host -> <emphasis remap='I'>query</emphasis>
- </para>
- <para>
-User-requested connect to some host -> <emphasis remap='I'>broadcast</emphasis>
- </para>
- <para>
-User-requested connect to site host-list -> <emphasis remap='I'>indirect</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>query</emphasis>:</term>
- <listitem>
- <para>
-Send <function>Query</function> packet
--> <emphasis remap='I'>collect-query</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>collect-query</emphasis>:</term>
- <listitem>
- <para>
-Receive <function>Willing</function> ->
-<emphasis remap='I'>start-connection</emphasis>
- </para>
- <para>
-Receive <function>Unwilling</function> ->
-<emphasis remap='I'>stop-connection</emphasis>
- </para>
- <para>
-Timeout -> <emphasis remap='I'>query</emphasis>
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><emphasis remap='I'>broadcast</emphasis>:</term>
- <listitem>
- <para>
-Send <function>BroadcastQuery</function> packet
- </para>
- <para>
--> <emphasis remap='I'>collect-broadcast-query</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>collect-broadcast-query</emphasis>:</term>
- <listitem>
- <para>
-Receive <function>Willing</function> ->
-<emphasis remap='I'>update-broadcast-willing</emphasis>
- </para>
- <para>
-User-requested connect to one host ->
-<emphasis remap='I'>start-connection</emphasis>
- </para>
- <para>
-Timeout -> <emphasis remap='I'>broadcast</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>update-broadcast-willing</emphasis>:</term>
- <listitem>
- <para>
-Add new host to the host list presented to the user
- </para>
- <para>
--> <emphasis remap='I'>collect-broadcast-query</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>indirect</emphasis>:</term>
- <listitem>
- <para>
-Send <function>IndirectQuery</function> packet
- </para>
- <para>
--> <emphasis remap='I'>collect-indirect-query</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>collect-indirect-query</emphasis>:</term>
- <listitem>
- <para>
-Receive <function>Willing</function> ->
-<emphasis remap='I'>update-indirect-willing</emphasis>
- </para>
- <para>
-User-requested connect to one host ->
-<emphasis remap='I'>start-connection</emphasis>
- </para>
- <para>
-Timeout -> <emphasis remap='I'>indirect</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>update-indirect-willing</emphasis>:</term>
- <listitem>
- <para>
-Add new host to the host list presented to the user
- </para>
- <para>
--> <emphasis remap='I'>collect-indirect-query</emphasis>
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><emphasis remap='I'>start-connection</emphasis>:</term>
- <listitem>
- <para>
-Send <function>Request</function> packet
- </para>
- <para>
--> <emphasis remap='I'>await-request-response</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>await-request-response</emphasis>:</term>
- <listitem>
- <para>
-Receive <function>Accept</function> ->
-<emphasis remap='I'>manage</emphasis>
- </para>
- <para>
-Receive <function>Decline</function> ->
-<emphasis remap='I'>stop-connection</emphasis>
- </para>
- <para>
-Timeout -> <emphasis remap='I'>start-connection</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>manage</emphasis>:</term>
- <listitem>
- <para>
-Save Session ID
- </para>
- <para>
-Send <function>Manage</function> packet with Session ID
- </para>
- <para>
--> <emphasis remap='I'>await-manage-response</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>await-manage-response</emphasis>:</term>
- <listitem>
- <para>
-Receive <function>XOpenDisplay :</function> ->
-<emphasis remap='I'>run-session</emphasis>
- </para>
- <para>
-Receive <function>Refuse</function> with matching Session ID
--> <emphasis remap='I'>start-connection</emphasis>
- </para>
- <para>
-Receive <function>Failed</function> with matching Session ID
--> <emphasis remap='I'>stop-connection</emphasis>
- </para>
- <para>
-Timeout -> <emphasis remap='I'>manage</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>stop-connection</emphasis>:</term>
- <listitem>
- <para>
-Display cause of termination to user
- </para>
- <para>
--> <emphasis remap='I'>start</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>run-session</emphasis>:</term>
- <listitem>
- <para>
-Decide to send <function>KeepAlive</function> packet ->
-<emphasis remap='I'>keep-alive</emphasis>
- </para>
- <para>
-wait close of first display connection
- </para>
- <para>
--> <emphasis remap='I'>reset-display</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>keep-alive</emphasis>:</term>
- <listitem>
- <para>
-Send <function>KeepAlive</function> packet with current Session ID
- </para>
- <para>
--> <emphasis remap='I'>await-alive</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>await-alive</emphasis>:</term>
- <listitem>
- <para>
-Receive <function>Alive</function> with matching Session ID ->
-<emphasis remap='I'>run-session</emphasis>
- </para>
- <para>
-Receive <function>Alive</function> with nonmatching Session ID
-or FALSE Session Running -> <emphasis remap='I'>reset-display</emphasis>
- </para>
- <para>
-Final timeout without receiving <function>Alive</function>
-packet -> <emphasis remap='I'>reset-display</emphasis>
- </para>
- <para>
-Timeout -> <emphasis remap='I'>keep-alive</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>reset-display</emphasis>:</term>
- <listitem>
- <para>
-(if possible) -> close all display connections associated with this session
- </para>
- <para>
-Last session -> close all display connections
- </para>
- <para>
--> <emphasis remap='I'>start</emphasis>
- </para>
- </listitem>
- </varlistentry>
-</variablelist>
-
-
-<para>
-Manager:
-</para>
-
-<variablelist>
- <varlistentry>
- <term><emphasis remap='I'>idle</emphasis>:</term>
- <listitem>
- <para>
-Receive <function>Query</function> ->
-<emphasis remap='I'>query-respond</emphasis>
- </para>
- <para>
-Receive
-<function>BroadcastQuery</function>
--> <emphasis remap='I'>broadcast-respond</emphasis>
- </para>
- <para>
-Receive
-<function>IndirectQuery</function>
--> <emphasis remap='I'>indirect-respond</emphasis>
- </para>
- <para>
-Receive
-<function>ForwardQuery</function>
--> <emphasis remap='I'>forward-respond</emphasis>
-Receive
- </para>
- <para>
-<function>Request</function>
--> <emphasis remap='I'>request-respond</emphasis>
- </para>
- <para>
-Receive
-<function>Manage</function>
--> <emphasis remap='I'>manage</emphasis>
- </para>
- <para>
-An active session terminates
--> <emphasis remap='I'>finish-session</emphasis>
- </para>
- <para>
-Receive <function>KeepAlive</function>
--> <emphasis remap='I'>send-alive</emphasis>
- </para>
- <para>
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>query-respond</emphasis>:</term>
- <listitem>
- <para>
-If willing to manage -> <emphasis remap='I'>send-willing</emphasis>
- </para>
- <para>
--> <emphasis remap='I'>send-unwilling</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>broadcast-respond</emphasis>:</term>
- <listitem>
- <para>
-If willing to manage -> <emphasis remap='I'>send-willing</emphasis>
- </para>
- <para>
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>indirect-respond</emphasis>:</term>
- <listitem>
- <para>
-Send <function>ForwardQuery</function>
-packets to all managers on redirect list
- </para>
- <para>
-If willing to manage -> <emphasis remap='I'>send-willing</emphasis>
- </para>
- <para>
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>forward-respond</emphasis>:</term>
- <listitem>
- <para>
-Decode destination address, if willing to manage ->
-<emphasis remap='I'>send-willing</emphasis>
- </para>
- <para>
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>send-willing</emphasis>:</term>
- <listitem>
- <para>
-Send <function>Willing</function> packet
- </para>
- <para>
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>send-unwilling</emphasis>:</term>
- <listitem>
- <para>
-Send <function>Unwilling</function> packet
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>request-respond</emphasis>:</term>
- <listitem>
- <para>
-If manager is willing to allow a session on display
--> <emphasis remap='I'>accept-session</emphasis>
- </para>
- <para>
--> <emphasis remap='I'>decline-session</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>accept-session</emphasis>:</term>
- <listitem>
- <para>
-Generate Session ID and save Session ID, display address, and
-display number somewhere
- </para>
- <para>
-Send <function>Accept</function> packet
- </para>
- <para>
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>decline-session</emphasis>:</term>
- <listitem>
- <para>
-Send <function>Decline</function> packet
- </para>
- <para>
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>manage</emphasis>:</term>
- <listitem>
- <para>
-If Session ID matches saved Session ID ->
-<emphasis remap='I'>run-session</emphasis>
- </para>
- <para>
-If Session ID matches Session ID of session in process of
-starting up, or currently active session ->
-<emphasis remap='I'>idle</emphasis>
- </para>
- <para>
--> <emphasis remap='I'>refuse</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>refuse</emphasis>:</term>
- <listitem>
- <para>
-Send <function>Refuse</function> packet
- </para>
- <para>
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>run-session</emphasis>:</term>
- <listitem>
- <para>
-Terminate any session in progress
- </para>
- <para>
-<function>XOpenDisplay</function>
- </para>
- <para>
-Open display succeeds ->
-<emphasis remap='I'>start-session</emphasis>
- </para>
- <para>
--> <emphasis remap='I'>failed</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>failed</emphasis>:</term>
- <listitem>
- <para>
-Send <function>Failed</function> packet
- </para>
- <para>
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>start-session</emphasis>:</term>
- <listitem>
- <para>
-Start a new session
- </para>
- <para>
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>finish-session</emphasis>:</term>
- <listitem>
- <para>
-<function>XCloseDisplay</function>
- </para>
- <para>
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><emphasis remap='I'>send-alive</emphasis>:</term>
- <listitem>
- <para>
-Send <function>Alive</function> packet containing current status
- </para>
- <para>
--> <emphasis remap='I'>idle</emphasis>
- </para>
- </listitem>
- </varlistentry>
-</variablelist>
-
-</chapter>
-
-<chapter id="Protocol_Encoding">
-<title>Protocol Encoding</title>
-<para>
-When XDMCP is implemented on top of the Internet User Datagram Protocol (UDP),
-port number 177 is to be used. When using UDP over IPv4, Broadcast Query
-packets are sent via UDP broadcast. When using UDP over IPv6, Broadcast Query
-packets are sent via multicast, either to an address in the IANA registered
-XDMCP multicast address range of
-FF0<emphasis remap='I'>X</emphasis>:0:0:0:0:0:0:12B
-(where the <emphasis remap='I'>X</emphasis> is replaced by a valid scope id)
-or to a locally assigned
-multicast address. The version number in all packets will be 1.
-Packet opcodes are 16-bit integers.
-</para>
-
-<informaltable frame="none">
- <tgroup cols='2' align='left'>
- <colspec colname='c1' colsep="0"/>
- <colspec colname='c2' colsep="0"/>
- <thead>
- <row>
- <entry>Packet Name</entry>
- <entry>Encoding</entry>
- </row>
- </thead>
- <tbody>
- <row rowsep="0">
- <entry>BroadcastQuery</entry>
- <entry>1</entry>
- </row>
- <row rowsep="0">
- <entry>Query</entry>
- <entry>2</entry>
- </row>
- <row rowsep="0">
- <entry>IndirectQuery</entry>
- <entry>3</entry>
- </row>
- <row rowsep="0">
- <entry>ForwardQuery</entry>
- <entry>4</entry>
- </row>
- <row rowsep="0">
- <entry>Willing</entry>
- <entry>5</entry>
- </row>
- <row rowsep="0">
- <entry>Unwilling</entry>
- <entry>6</entry>
- </row>
- <row rowsep="0">
- <entry>Request</entry>
- <entry>7</entry>
- </row>
- <row rowsep="0">
- <entry>Accept</entry>
- <entry>8</entry>
- </row>
- <row rowsep="0">
- <entry>Decline</entry>
- <entry>9</entry>
- </row>
- <row rowsep="0">
- <entry>Manage</entry>
- <entry>10</entry>
- </row>
- <row rowsep="0">
- <entry>Refuse</entry>
- <entry>11</entry>
- </row>
- <row rowsep="0">
- <entry>Failed</entry>
- <entry>12</entry>
- </row>
- <row rowsep="0">
- <entry>KeepAlive</entry>
- <entry>13
-<footnote><para>
-A previous version of this document incorrectly reversed the opcodes of
-<emphasis role="bold">Alive</emphasis> and
-<emphasis role="bold">KeepAlive</emphasis>.
-</para></footnote>
- </entry>
- </row>
- <row rowsep="0">
- <entry>Alive</entry>
- <entry>14
-<footnote><para>
-A previous version of this document incorrectly reversed the opcodes of
-<emphasis role="bold">Alive</emphasis> and
-<emphasis role="bold">KeepAlive</emphasis>.
-</para></footnote>
- </entry>
- </row>
- </tbody>
- </tgroup>
-</informaltable>
-
-<para>
-Per packet information follows:
-</para>
-
-<para>
-<function>Query</function>,
-<function>BroadcastQuery</function>,
-<function>IndirectQuery</function>
-</para>
-
-<literallayout class="monospaced">
- 2 CARD16 version number (always 1)
- 2 CARD16 opcode (always Query, BroadcastQuery or IndirectQuery)
- 2 CARD16 length
- 1 CARD8 number of Authentication Names sent (m)
- 2 CARD16 length of first Authentication Name (m<emphasis role="subscript">1</emphasis>)
- m<emphasis role="subscript">1</emphasis> CARD8 first Authentication Name
- ... Other Authentication Names
-</literallayout>
-
-<para>
-Note that these three packets are identical except for the opcode field.
-</para>
-
-<literallayout class="monospaced">
-<function>ForwardQuery</function>
- 2 CARD16 version number (always 1)
- 2 CARD16 opcode (always ForwardQuery)
- 2 CARD16 length
- 2 CARD16 length of Client Address (m)
- m CARD8 Client Address
- 2 CARD16 length of Client Port (n)
- n CARD8 Client Port
- 1 CARD8 number of Authentication Names sent (o)
- 2 CARD16 length of first Authentication Name (o<emphasis role="subscript">1</emphasis>)
- o<emphasis role="subscript">1</emphasis> CARD8 first Authentication Name
- ... Other Authentication Names
-</literallayout>
-
-<literallayout class="monospaced">
-<function>Willing</function>
- 2 CARD16 version number (always 1)
- 2 CARD16 opcode (always Willing)
- 2 CARD16 length (6 + m + n + o)
- 2 CARD16 Length of Authentication Name (m)
- m CARD8 Authentication Name
- 2 CARD16 Hostname length (n)
- n CARD8 Hostname
- 2 CARD16 Status length (o)
- o CARD8 Status
-</literallayout>
-
-<literallayout class="monospaced">
-<function>Unwilling</function>
- 2 CARD16 version number (always 1)
- 2 CARD16 opcode (always Unwilling)
- 2 CARD16 length (4 + m + n)
- 2 CARD16 Hostname length (m)
- m CARD8 Hostname
- 2 CARD16 Status length (n)
- n CARD8 Status
-</literallayout>
-
-<literallayout class="monospaced">
-<function>Request</function>
- 2 CARD16 version number (always 1)
- 2 CARD16 opcode (always Request)
- 2 CARD16 length
- 2 CARD16 Display Number
- 1 CARD8 Count of Connection Types (m)
- 2xm CARD16 Connection Types
- 1 CARD8 Count of Connection Addresses (n)
- 2 CARD16 Length of first Connection Address (n<emphasis role="subscript">1</emphasis>)
- n<emphasis role="subscript">1</emphasis> CARD8 First Connection Address
- ... Other connection addresses
- 2 CARD16 Length of Authentication Name (o)
- o CARD8 Authentication Name
- 2 CARD16 Length of Authentication Data (p)
- p CARD8 Authentication Data
- 1 CARD8 Count of Authorization Names (q)
- 2 CARD16 Length of first Authorization Name (q<emphasis role="subscript">1</emphasis>)
- q<emphasis role="subscript">1</emphasis> CARD8 First Authorization Name
- ... Other authorization names
- 2 CARD16 Length of Manufacturer Display ID (r)
- r CARD8 Manufacturer Display ID
-</literallayout>
-
-<literallayout class="monospaced">
-<function>Accept</function>
- 2 CARD16 version number (always 1)
- 2 CARD16 opcode (always Accept)
- 2 CARD16 length (12 + n + m + o + p)
- 4 CARD32 Session ID
- 2 CARD16 Length of Authentication Name (n)
- n CARD8 Authentication Name
- 2 CARD16 Length of Authentication Data (m)
- m CARD8 Authentication Data
- 2 CARD16 Length of Authorization Name (o)
- o CARD8 Authorization Name
- 2 CARD16 Length of Authorization Data (p)
- p CARD8 Authorization Data
-</literallayout>
-
-<literallayout class="monospaced">
-<function>Decline</function>
- 2 CARD16 version number (always 1)
- 2 CARD16 opcode (always Decline)
- 2 CARD16 length (6 + m + n + o)
- 2 CARD16 Length of Status (m)
- m CARD8 Status
- 2 CARD16 Length of Authentication Name (n)
- n CARD8 Authentication Name
- 2 CARD16 Length of Authentication Data (o)
- o CARD8 Authentication Data
-</literallayout>
-
-<literallayout class="monospaced">
-<function>Manage</function>
- 2 CARD16 version number (always 1)
- 2 CARD16 opcode (always Manage)
- 2 CARD16 length (8 + m)
- 4 CARD32 Session ID
- 2 CARD16 Display Number
- 2 CARD16 Length of Display Class (m)
- m CARD8 Display Class
-</literallayout>
-
-<literallayout class="monospaced">
-<function>Refuse</function>
- 2 CARD16 version number (always 1)
- 2 CARD16 opcode (always Refuse)
- 2 CARD16 length (4)
- 4 CARD32 Session ID
-</literallayout>
-
-<literallayout class="monospaced">
-<function>Failed</function>
- 2 CARD16 version number (always 1)
- 2 CARD16 opcode (always Failed)
- 2 CARD16 length (6 + m)
- 4 CARD32 Session ID
- 2 CARD16 Length of Status (m)
- m CARD8 Status
-</literallayout>
-
-<literallayout class="monospaced">
-<function>KeepAlive</function>
- 2 CARD16 version number (always 1)
- 2 CARD16 opcode (always KeepAlive)
- 2 CARD16 length (6)
- 2 CARD16 Display Number
- 4 CARD32 Session ID
-</literallayout>
-
-<literallayout class="monospaced">
-<function>Alive</function>
- 2 CARD16 version number (always 1)
- 2 CARD16 opcode (always Alive)
- 2 CARD16 length (5)
- 1 CARD8 Session Running (0: not running 1: running)
- 4 CARD32 Session ID (0: not running)
-</literallayout>
-</chapter>
-
-<chapter id="Display_Class_Format">
-<title>Display Class Format</title>
-<!-- .XS -->
-<!-- (SN Display Class Format -->
-<!-- .XE -->
-<para>
-The Display Class field of the
-<function>Manage</function>
-packet is used by the display manager to collect common sorts of
-displays into manageable groups. This field is a string encoded of
-ISO-LATIN-1 characters in the following format:
-</para>
-
-<literallayout class="monospaced">
-<emphasis remap='I'>ManufacturerID</emphasis>-<emphasis remap='I'>ModelNumber</emphasis>
-</literallayout>
-
-<para>
-Both elements of this string must exclude characters of the set
-{ <function>-</function>,
-<function>.</function>,
-<function>:</function>,
-<function>*</function>,
-<function>?</function>,
-<emphasis remap='I'><space></emphasis> }.
-The ManufacturerID is a string that should be registered
-with the X Consortium.
-The ModelNumber is designed to identify characteristics of the display
-within the manufacturer's product line.
-This string should be documented in the users manual for the
-particular device and should probably not be specifiable by the
-display user to avoid unexpected configuration errors.
-</para>
-</chapter>
-
-<chapter id="Manufacturer_Display_ID_Format">
-<title>Manufacturer Display ID Format</title>
-<!-- .XS -->
-<!-- (SN Manufacturer Display ID Format -->
-<!-- .XE -->
-<para>
-To authenticate the manager, the display and manager will share a private
-key.
-The manager, then, must be able to discover which key to use for a
-particular device.
-The Manufacturer Display ID field of the
-<function>Request</function>
-packet is intended for this purpose. Typically, the manager host will
-contain a map between this number and the key. This field is intended to be
-unique per display, possibly the ethernet address of the display in the form:
-</para>
-
-<literallayout class="monospaced">
--Ethernet-8:0:2b:a:f:d2
-</literallayout>
-
-<para>
-It can also be a string of the form:
-</para>
-
-<literallayout class="monospaced">
-<emphasis remap='I'>ManufacturerID</emphasis>-<emphasis remap='I'>ModelNumber</emphasis>-<emphasis remap='I'>SerialNumber</emphasis>
-</literallayout>
-
-<para>
-The ManufacturerID, ModelNumber and SerialNumber are encoded using
-ISO-LATIN-1 characters, excluding {
-<function>-</function>,
-<function>.</function>,
-<function>*</function>,
-<function>?</function>,
-<emphasis remap='I'><space></emphasis> }
-</para>
-
-<para>
-When the display is shipped to a customer, it should include both the
-Manufacturer Display ID and the private key in the documentation set.
-This information should not be modifiable by the display user.
-</para>
-
-</chapter>
-
-<chapter id="Authentication">
-<title>Authentication</title>
-<!-- .XS -->
-<!-- (SN Authentication -->
-<!-- .XE -->
-<para>
-In an environment where authentication is not needed, XDMCP can disable
-authentication by having the display send empty Authentication Name
-and Authentication Data fields in the
-<function>Request</function>
-packet.
-In this case, the manager will not attempt to authenticate itself.
-Other authentication protocols may be developed, depending on local needs.
-</para>
-
-<para>
-In an unsecure environment, the display must be able to verify that the
-source of the various packets is a trusted manager. These packets will
-contain authentication information. As an example of such a system, the
-following discussion describes the "XDM-AUTHENTICATION-1" authentication
-system. This system uses a 56-bit shared private key, and 64 bits of
-authentication data. An associated example X authorization protocol
-"XDM-AUTHORIZATION-1" will also be discussed. The 56-bit key is represented
-as a 64-bit number in network order (big endian). This means that the first
-octet in the representation will be zero. When incrementing a 64-bit value,
-the 8 octets of data will be interpreted in network order (big endian).
-That is, the last octet will be incremented, subsequent carries propogate
-towards the first octet.
-</para>
-
-<para>
-Assumptions:
-</para>
-
-<orderedlist>
- <listitem>
- <para>
-The display and manager share a private key. This key could be programmed
-into the display by the manufacturer and shipped with the unit. It must not
-be available from the display itself, but should allow the value to be
-modified in some way. The system administrator would be responsible for
-managing a database of terminal keys.
- </para>
- </listitem>
- <listitem>
- <para>
-The display can generate random authentication numbers.
- </para>
- </listitem>
-</orderedlist>
-
-<para>
-Some definitions first:
-</para>
-
-<!-- FIXME: -->
-<!-- double chk math symbols, use mathml to display them? -->
-<itemizedlist>
- <listitem>
- <para>
-{&variable.D;}<superscript>&variable.kappa;</superscript> = encryption of plain text D by key &variable.kappa;
- </para>
- </listitem>
- <listitem>
- <para>
-{&variable.Delta;}*<superscript>&variable.kappa;</superscript> = decryption of crypto text &variable.Delta; with key &variable.kappa;
- </para>
- </listitem>
- <listitem>
- <para>
-&variable.tau; = private key shared by display and manager
- </para>
- </listitem>
- <listitem>
- <para>
-&variable.rho; = 64 bit random number generated by display
- </para>
- </listitem>
- <listitem>
- <para>
-&variable.alpha; = authentication data in XDMCP packets
- </para>
- </listitem>
- <listitem>
- <para>
-&variable.sigma; = per-session private key, generated by manager
- </para>
- </listitem>
- <listitem>
- <para>
-&variable.beta; = authorization data
- </para>
- </listitem>
-</itemizedlist>
-
-<para>
-Encryption will use the Data Encryption Standard (DES, FIPS 46-3); blocks
-shorter than 64 bits will be zero-filled
-on the right to 64 bits. Blocks longer than 64 bits will use block chaining:
-</para>
-<para>
-{&variable.D;}<superscript>&variable.kappa;</superscript> = {&variable.D;<subscript>1</subscript>}<superscript>&variable.kappa;</superscript> {&variable.D;<subscript>2</subscript> xor {&variable.D;<subscript>1</subscript>}<superscript>&variable.kappa;</superscript>}<superscript>&variable.kappa;</superscript>
-</para>
-
-<para>
-The display generates the first authentication data in the
-<function>Request</function>
-packet:
-</para>
-
-<para>
-&variable.alpha;<subscript>Request</subscript> = {&variable.rho;}<superscript>&variable.tau;</superscript>
-</para>
-
-<para>
-For the <function>Accept</function>
-packet, the manager decrypts the initial message and returns
-&variable.alpha;<subscript>Accept</subscript>:
-
-</para>
-
-<para>
-&variable.rho; = {&variable.alpha;<subscript>Request</subscript>}*<superscript>&variable.tau;</superscript>
-</para>
-
-<para>
-&variable.alpha;<subscript>Accept</subscript> = { &variable.rho; + 1}<superscript>&variable.tau;</superscript>
-</para>
-
-<para>
-The <function>Accept</function>
-packet also contains the authorization intended for use by
-the X server. A description of authorization type "XDM-AUTHORIZATION-1"
-follows.
-</para>
-
-<para>
-The <function>Accept</function>
-packet contains the authorization name
-"XDM-AUTHORIZATION-1". The authorization data is the string:
-</para>
-<para>
-&variable.beta;<subscript>Accept</subscript> = {&variable.sigma;}<superscript>&variable.tau;</superscript>
-</para>
-
-<para>
-To create authorization information for connection setup with the X server
-using the XDM-AUTHORIZATION-1 authorization protocol, the client computes the
-following:
-</para>
-<para>
-&variable.N; = X client identifier
-</para>
-<para>
-&variable.T; = Current time in seconds on client host (32 bits)
-</para>
-<para>
-&variable.beta; = {&variable.rho;&variable.N;&variable.T;}<superscript>&variable.sigma;</superscript>
-</para>
-
-<para>
-For TCP connections &variable.N; is 48 bits long and contains the 32-bit IPv4 address of
-the client host followed by the 16-bit port number of the client socket.
-Formats for other connections must be registered.
-The resulting value, &variable.beta;, is 192 bits of authorization data that is sent
-in the connection setup to the server. The server receives the packet,
-decrypts the contents. To accept the connection, the following must hold:
-</para>
-
-<itemizedlist>
- <listitem>
- <para>
-&variable.rho; must match the value generated for the most recent XDMCP negotiation.
- </para>
- </listitem>
- <listitem>
- <para>
-&variable.T; must be within 1200 seconds of the internally stored time. If no time
-been received before, the current time is set to &variable.T;.
- </para>
- </listitem>
- <listitem>
- <para>
-No packet containing the same pair (&variable.N;, &variable.T;) can have been received
-in the last 1200 seconds (20 minutes).
- </para>
- </listitem>
-</itemizedlist>
-</chapter>
-</book>
+<?xml version="1.0" encoding="UTF-8" ?> +<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" + "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [ +<!-- + variable names used in equation markup in the authentication chapter + FIXME: Replace with mathml? + --> +<!ENTITY variable.D "<emphasis role='italic'>D</emphasis>"> +<!ENTITY variable.N "<emphasis role='italic'>N</emphasis>"> +<!ENTITY variable.T "<emphasis role='italic'>T</emphasis>"> +<!ENTITY variable.Delta "<emphasis role='italic'>Δ</emphasis>"> +<!ENTITY variable.alpha "<emphasis role='italic'>α</emphasis>"> +<!ENTITY variable.beta "<emphasis role='italic'>β</emphasis>"> +<!ENTITY variable.kappa "<emphasis role='italic'>κ</emphasis>"> +<!ENTITY variable.rho "<emphasis role='italic'>ρ</emphasis>"> +<!ENTITY variable.sigma "<emphasis role='italic'>σ</emphasis>"> +<!ENTITY variable.tau "<emphasis role='italic'>τ</emphasis>"> +<!ENTITY % defs SYSTEM "defs.ent"> %defs; +]> + +<book id="xdmcp"> + +<bookinfo> + <title>X Display Manager Control Protocol</title> + <subtitle>X.Org Standard</subtitle> + <releaseinfo>X Version 11, Release &fullrelvers;</releaseinfo> + <releaseinfo>Version 1.1</releaseinfo> + <authorgroup> + <author> + <firstname>Keith</firstname><surname>Packard</surname> + <affiliation> + <orgname>Massachusetts Institute of Technology</orgname> + <orgdiv>Laboratory for Computer Science</orgdiv> + <orgdiv>X Consortium</orgdiv> + </affiliation> + </author> + </authorgroup> + + <copyright><year>1989</year><year>2004</year> + <holder>The Open Group</holder></copyright> + +<legalnotice> + + + +<para> +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: +</para> +<para> +The above copyright notice and this permission notice shall be included in +all copies or substantial portions of the Software. +</para> +<para> +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN +AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN +CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. +</para> +<para> +Except as contained in this notice, the name of The Open Group shall not be +used in advertising or otherwise to promote the sale, use or other dealings +in this Software without prior written authorization from The Open Group. +</para> + +<para> +<emphasis remap='I'>X Window System</emphasis> is a trademark of The Open Group. +</para> +</legalnotice> +</bookinfo> + +<chapter id="Purpose_and_Goals"> +<title>Purpose and Goals</title> +<!-- .XS --> +<!-- (SN Purpose and Goals --> +<!-- .XE --> +<para> +<!-- .LP --> +The purpose of the X Display Manager Control Protocol (XDMCP) +is to provide a uniform mechanism for an autonomous +display to request login service from a remote host. +By autonomous, we mean +the display consists of hardware and processes that are independent of any +particular host where login service is desired. (For example, the server +cannot simply be started by a +<function>fork/exec</function> +sequence on the host.) +An X terminal (screen, keyboard, mouse, processor, network interface) +is a prime example of an autonomous display. +</para> + +<para> +From the point of view of the end user, it is very important to make +autonomous displays as easy to use as traditional hardwired character +terminals. Specifically, you can typically just power on a hardwired +terminal and be greeted with a login prompt. The same should be possible +with autonomous displays. However, in a network environment with multiple +hosts, the end user may want to choose which host(s) to connect to. In an +environment with many displays and many hosts, a site administrator may want +to associate particular collections of hosts with particular displays. We +would like to support the following options: +</para> + +<itemizedlist> + <listitem> + <para> +The display has a single, fixed host to which it should connect. It should be +possible to power on the display and receive a login prompt, without user +intervention. + </para> + </listitem> + <listitem> + <para> +Any one of several hosts on a network or subnetwork may be acceptable +for accepting login from the display. +(For example, the user's file systems can be mounted onto +any such host, providing comparable environments.) It should be possible +for the display to broadcast to find such hosts and to have the display +either automatically choose a host or present the possible hosts to the +user for selection. + </para> + </listitem> + <listitem> + <para> +The display has a fixed set of hosts that it can connect to. It should be +possible for the display to have that set stored in RAM, but it should also be +possible for a site administrator to be able to maintain host sets for a +large number of displays using a centralized facility, without having to +interact (physically or electronically) with each individual display. +Particular hosts should be allowed to refuse login service, based on +whatever local criteria are desired. + </para> + </listitem> +</itemizedlist> + +<para> +The control protocol should be designed in such a way that it can be used over +a reasonable variety of communication transport layers. In fact, it is quite +desirable if every major network protocol family that supports the standard X +protocol is also capable of supporting XDMCP, because the end result of XDMCP +negotiation will be standard X protocol connections to the display. +However, because the number of displays per host may be large, +a connection-based protocol appears less desirable +than a connection-less protocol. For this reason the protocol is designed +to use datagram services with the display responsible for sequencing and +retransmission. +</para> +<para> +<!-- .LP --> +To keep the burden on displays at a minimum (because display cost is not +a factor that can be ignored), it is desirable that displays not be required +to maintain permanent state (across power cycles) for the purposes +of the control protocol, +and it is desirable to keep required state at a minimum while the +display is powered on. +</para> +<para> +<!-- .LP --> +Security is an important consideration and must be an integral part of the +design. The important security goals in the context of XDMCP are: +</para> +<itemizedlist> + <listitem> + <para> +It should be possible for the display to verify that it is communicating +with a legitimate host login service. Because the user will present +credentials (for example, password) to this service, +it is important to avoid spoof attacks. + </para> + </listitem> + <listitem> + <para> +It should be possible for the display and the login service to negotiate the +authorization mechanism to be used for the standard X protocol. + </para> + </listitem> + <listitem> + <para> +It should be possible to provide the same level of security in verifying the +login service as is provided by the negotiated authorization mechanism. + </para> + </listitem> + <listitem> + <para> +Because there are no firm standards yet in the area of security, +XDMCP must be flexible enough to accomodate a variety of security mechanisms. + </para> + </listitem> +</itemizedlist> +</chapter> + +<chapter id="Overview_of_the_Protocol"> +<title>Overview of the Protocol</title> +<!-- .XS --> +<!-- (SN Overview of the Protocol --> +<!-- .XE --> +<para> +<!-- .LP --> +XDMCP is designed to provide authenticated access to display management +services for remote displays. A new network server, called a \fIDisplay +Manager\fP, will use XDMCP to communicate with displays to negotiate the +startup of X sessions. The protocol allows the display to authenticate the +manager. It also allows most of the configuration information to be +centralized with the manager and to ease the burden of system administration +in a large network of displays. +The essential goal is to provide plug-and-play +services similar to those provided in the familiar mainframe/terminal world. +</para> +<para> +<!-- .LP --> +Displays may be turned off by the user at any time. Any existing session +running on a display that has been turned off must be identifiable. This +is made possible by requiring a three-way handshake to start a session. If +the handshake succeeds, any existing session is terminated immediately and a +new session started. There is the problem (at least with TCP) that +connections may not be closed when the display is turned off. In most +environments, the manager should reduce this problem by periodically XSync'ing +on its own connection, perhaps every five to ten minutes, and terminating the +session if its own connection ever closes. +</para> +<para> +<!-- .LP --> +Displays should not be required to retain permanent state for purposes of +the control protocol. One solution to packets received out of sequence +would be to use monotonically increasing message identifiers in each message +to allow both sides to ignore messages that arrive out-of-sequence. For +this to work, displays would at a minimum have to increment a stable crash +count each time they are powered on and use that number as part of a +larger sequence number. But if displays cannot retain permanent state this +cannot work. Instead, the manager assumes the responsibility for permanent +state by generating unique numbers that identify a particular session and +the protocol simply ignores packets that correspond to an invalid session. +</para> +<para> +<!-- .LP --> +The Manager must not be responsible for packet reception. To prevent the +Manager from becoming stuck because of a hostile display, no portion of the +protocol requires the Manager to retransmit a packet. Part of this means +that any valid packet that the Manager does receive must be +acknowledged in some way to prevent the display from continuously resending +packets. The display can keep the protocol running as it will always know +when the Manager has received (at least one copy of) a packet. On the +Manager side, this means that any packet may be received more than once (if +the response was lost) and duplicates must be ignored. +</para> +</chapter> + +<chapter id="Data_Types"> +<title>Data Types</title> +<!-- .XS --> +<!-- (SN Data Types --> +<!-- .XE --> +<para> +<!-- .LP --> +XDMCP packets contain several types of data. Integer values are always +stored most significant byte first in the packet ("Big Endian" order). +As XDMCP will not be used to transport large quantities of data, this +restriction will not substantially hamper the efficiency of any +implementation. Also, no padding of any sort will occur within the packets. +</para> + +<informaltable frame="none"> + <tgroup cols='3' align='left'> + <colspec colname='c1' colsep="0"/> + <colspec colname='c2' colsep="0"/> + <colspec colname='c3' colsep="0"/> + <thead> + <row> + <entry>Type Name</entry> + <entry>Length (Bytes)</entry> + <entry>Description</entry> + </row> + </thead> + <tbody> + <row rowsep="0"> + <entry>CARD8</entry> + <entry>1</entry> + <entry>A single byte unsigned integer</entry> + </row> + <row rowsep="0"> + <entry>CARD16</entry> + <entry>2</entry> + <entry>Two byte unsigned integer</entry> + </row> + <row rowsep="0"> + <entry>CARD32</entry> + <entry>4</entry> + <entry>Four byte unsigned integer</entry> + </row> + <row rowsep="0"> + <entry>ARRAY8</entry> + <entry>n+2</entry> + <entry> +This is actually a CARD16 followed by +a collection of CARD8. The value of the CARD16 +field (n) specifies the number of CARD8 values to follow + </entry> + </row> + <row rowsep="0"> + <entry>ARRAY16</entry> + <entry>2*m+1</entry> + <entry> +This is a CARD8 (m) which specifies the +number of CARD16 values to follow + </entry> + </row> + <row rowsep="0"> + <entry>ARRAY32</entry> + <entry>4*l+1</entry> + <entry> +This is a CARD8 (l) which specifies the +number of CARD32 values to follow + </entry> + </row> + <row rowsep="0"> + <entry>ARRAYofARRAY8</entry> + <entry>?</entry> + <entry> +This is a CARD8 which specifies the +number of ARRAY8 values to follow. + </entry> + </row> + </tbody> + </tgroup> +</informaltable> +</chapter> + +<chapter id="Packet_Format"> +<title>Packet Format</title> +<!-- .XS --> +<!-- (SN Packet Format --> +<!-- .XE --> +<para> +All XDMCP packets have the following information: +</para> + +<informaltable frame="none"> + <tgroup cols='3' align='left'> + <colspec colname='c1' colsep="0"/> + <colspec colname='c2' colsep="0"/> + <colspec colname='c3' colsep="0"/> + <thead> + <row> + <entry>Length (Bytes)</entry> + <entry>Field Type</entry> + <entry>Description</entry> + </row> + </thead> + <tbody> + <row rowsep="0"> + <entry>2</entry> + <entry>CARD16</entry> + <entry>version number</entry> + </row> + <row rowsep="0"> + <entry>2</entry> + <entry>CARD16</entry> + <entry>opcode packet header</entry> + </row> + <row rowsep="0"> + <entry>2</entry> + <entry>CARD16</entry> + <entry>n = length of remaining data in bytes</entry> + </row> + <row rowsep="0"> + <entry>n</entry> + <entry>???</entry> + <entry>packet-specific data</entry> + </row> + </tbody> + </tgroup> +</informaltable> + +<para> +<!-- .LP --> +The fields are as follows: +</para> + +<variablelist> + <varlistentry> + <term>Version number</term> + <listitem> + <para> +This specifies the version of XDMCP that generated this packet in +case changes in this protocol are required. Displays and +managers may choose to support older versions for compatibility. +This field will initially be one (1). + </para> + </listitem> + </varlistentry> + <varlistentry> + <term>Opcode</term> + <listitem> + <para> +This specifies what step of the protocol this packet represents and should +contain one of the following values (encoding provided in section below): +<emphasis role="bold">BroadcastQuery</emphasis>, +<emphasis role="bold">Query</emphasis>, +<emphasis role="bold">IndirectQuery</emphasis>, +<emphasis role="bold">ForwardQuery</emphasis>, +<emphasis role="bold">Willing</emphasis>, +<emphasis role="bold">Unwilling</emphasis>, +<emphasis role="bold">Request</emphasis>, +<emphasis role="bold">Accept</emphasis>, +<emphasis role="bold">Decline</emphasis>, +<emphasis role="bold">Manage</emphasis>, +<emphasis role="bold">Refuse</emphasis>, +<emphasis role="bold">Failed</emphasis>, +<emphasis role="bold">KeepAlive</emphasis> +or +<emphasis role="bold">Alive</emphasis>. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term>Length of data in bytes</term> + <listitem> + <para> +This specifies the length of the information following the first 6 bytes. +Each packet-type has a different format and will need to be separately +length-checked against this value. Because every data item has either an +explicit or implicit length, this can be easily accomplished. +Packets that have too little or too much data should be ignored. + </para> + </listitem> + </varlistentry> +</variablelist> +<para> +Packets should be checked to make sure that they satisfy the following +conditions: +</para> + +<orderedlist> + <listitem> + <para> +They must contain valid opcodes. + </para> + </listitem> + <listitem> + <para> +The length of the remaining data should correspond to the sum of the +lengths of the individual remaining data items. + </para> + </listitem> + <listitem> + <para> +The opcode should be expected (a finite state diagram is given +in a later section). + </para> + </listitem> + <listitem> + <para> +If the packet is of type +<emphasis role="bold">Manage</emphasis> or +<emphasis role="bold">Refuse</emphasis>, +the Session ID should match the value sent in the preceding +<emphasis role="bold">Accept</emphasis> packet. + </para> + </listitem> +</orderedlist> +</chapter> + +<chapter id="Protocol"> +<title>Protocol</title> +<!-- .XS --> +<!-- (SN Protocol --> +<!-- .XE --> +<para> +Each of the opcodes is described below. Because a given packet type is only +ever sent one way, each packet description below indicates the direction. +Most of the packets have additional information included beyond the +description above. The additional information is appended to the packet +header in the order described without padding, and the length field is +computed accordingly. +</para> + +<informaltable frame="none"> + <tgroup cols='10' align='left'> + <colspec colname='col1' colsep="0" colwidth="1*"/> + <colspec colname='col2' colsep="0" colwidth="1*"/> + <colspec colname='col3' colsep="0" colwidth="1*"/> + <colspec colname='col4' colsep="0" colwidth="1*"/> + <colspec colname='col5' colsep="0" colwidth="1*"/> + <colspec colname='col6' colsep="0" colwidth="1*"/> + <colspec colname='col7' colsep="0" colwidth="1*"/> + <colspec colname='col8' colsep="0" colwidth="1*"/> + <colspec colname='col9' colsep="0" colwidth="1*"/> + <colspec colname='col10' colsep="0" colwidth="1*"/> + <spanspec namest="col1" nameend="col10" spanname="col1_on" align="left"/> + <spanspec namest="col2" nameend="col10" spanname="col2_on" align="left"/> + <spanspec namest="col3" nameend="col10" spanname="col3_on" align="left"/> + <spanspec namest="col4" nameend="col10" spanname="col4_on" align="left"/> + <spanspec namest="col5" nameend="col10" spanname="col5_on" align="left"/> + <tbody> + <row rowsep="0"> + <entry spanname="col1_on"><emphasis role="bold">Query</emphasis></entry> + </row> + <row rowsep="0"> + <entry spanname="col1_on"><emphasis role="bold">BroadcastQuery</emphasis></entry> + </row> + <row rowsep="0"> + <entry spanname="col1_on"><emphasis role="bold">IndirectQuery</emphasis></entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on">Display -> Manager</entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on">Additional Fields:</entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis>Authentication Names</emphasis>: ARRAYofARRAY8 + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Specifies a list of authentication names that the display supports. The +manager will choose one of these and return it in the +<emphasis role="bold">Willing</emphasis> packet. + </entry> + </row> +<!-- AAAAAAAAAAAAA --> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry>Semantics</entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +<para> +A <function>Query</function> +packet is sent from the display to a specific host to ask if +that host is willing to provide management services to this display. The +host should respond with +<function>Willing</function> +if it is willing to service the display or +<function>Unwilling</function> +if it is not. +</para> + +<para> +A +<function>BroadcastQuery</function> +packet is similar to the +<function>Query</function> +packet except that it is intended to be received by all hosts on the network +(or subnetwork). However, unlike +<function>Query</function> +requests, hosts that are not willing to service the display +should simply ignore +<function>BroadcastQuery</function> +requests. +</para> + +<para> +An +<function>IndirectQuery</function> +packet is sent to a well known manager that forwards +the request to a larger collection of secondary managers using +<function>ForwardQuery</function> +packets. +In this way, the collection of managers that respond can be grouped +on other than network boundaries; the use of a central manager reduces +system administrative overhead. +The primary manager may also send a +<function>Willing</function> +packet in response to this packet. +</para> + +<para> +Each packet type has slightly different semantics: +</para> + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +<para> +The +<function>Query</function> +packet is destined only for a single host. +If the display is instructed to +<function>Query</function> +multiple managers, it will send multiple +<function>Query</function> +packets. The +<function>Query</function> +packet also demands a response from the manager, either +<function>Willing</function> +or +<function>Unwilling</function>. + </para> + <para> +The +<function>BroadcastQuery</function> +packet is sent to many hosts. +Each manager that receives this packet will not respond with an +<function>Unwilling</function> +packet. + </para> + <para> +The +<function>IndirectQuery</function> +packet is sent to only one manager with the request +that the request be forwarded to a larger list of managers using +<function>ForwardQuery</function> +packets. This list is expected to be maintained at one +central site to reduce administrative overhead. +The function of this packet type is similar to +<function>BroadcastQuery except that</function> +<function>BroadcastQuery</function> +is not forwarded. + </para> + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on">Valid Responses:</entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<function>Willing</function>, +<function>Unwilling</function> + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on">Problems/Solutions:</entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on">Problem:</entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +<para>Not all managers receive the query packet.</para> +<para>Indication:</para> + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +None if +<function>BroadcastQuery</function> +or +<function>IndirectQuery</function> +was sent, else failure to receive +<function>Willing</function>. + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on">Solution:</entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Repeatedly send the packet while waiting for user to choose a manager. + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Timeout/Retransmission policy: + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +An exponential backoff algorithm should be used here to reduce network load +for long-standing idle displays. Start at 2 seconds, back off by factors of +2 to 32 seconds, and discontinue retransmit after 126 seconds. The display +should reset the timeout when user-input is detected. In this way, the +display will wakeup when touched by the user. + </entry> + </row> + <row rowsep="0"> + <entry spanname="col1_on"> +<function>ForwardQuery</function> + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +<para>Primary Manager -> Secondary Manager</para> +<para>Additional Fields:</para> + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Client Address</emphasis>: ARRAY8 + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Specifies the network address of the client display. + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Client Port</emphasis>: ARRAY8 + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Specifies an identification of the client task on the client display. + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Authentication Names</emphasis>: ARRAYofARRAY8 + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Is a duplicate of Authentication Names array that was received +in the +<function>IndirectQuery</function> +packet. + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Semantics: + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> + <para> +When primary manager receives a +<function>IndirectQuery</function> +packet, it is responsible for sending +<function>ForwardQuery</function> +packets to an appropriate list of +managers that can provide service to the display using the same network +type as the one the original +<function>IndirectQuery</function> +packet was received from. +The Client Address and Client Port fields must contain an +address that the secondary manager can use to reach the display also using +this same network. Each secondary manager sends a +<function>Willing</function> +packet to the display if it is willing to provide service. + </para> + + <para> +<function>ForwardQuery</function> +packets are similar to +<function>BroadcastQuery</function> +packets in that managers that are not willing to service +particular displays should not send a +<function>Unwilling</function> +packet. + </para> + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Valid Responses: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<function>Willing</function> + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Problems/Solutions: + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Identical to +<function>BroadcastQuery</function> + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Timeout/Retransmission policy: + </entry> + </row> + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Like all packets sent from a manager, this packet should never be +retransmitted. + </entry> + </row> + + <row rowsep="0"> + <entry spanname="col1_on"> +<function>Willing</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> + <para> +Manager -> Display + </para> + <para> +Additional Fields: + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Authentication Name</emphasis>: ARRAY8 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +<para> +Specifies the authentication method, selected from the list offered in the +<function>Query ,</function> +<function>BroadcastQuery ,</function> +or +<function>IndirectQuery</function> +packet that the manger expects the display to use in the subsequent +<function>Request</function> +packet. +This choice should remain as constant as feasible so that displays that +send multiple +<function>Query</function> +packets can use the Authentication Name from any +<function>Willing</function> +packet that arrives. +</para> +<para> +The display is free to ignore managers that request an insufficient level +of authentication. +</para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Hostname</emphasis>: ARRAY8 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Is a human readable string describing the host from which the packet was sent. +The protocol specifies no interpretation of the data in this field. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Status</emphasis>: ARRAY8 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Is a human readable string describing the status of the host. This could +include load average/number of users connected or other information. The +protocol specifies no interpretation of the data in this field. + </entry> + </row> + + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Semantics: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +A +<function>Willing</function> +packet is sent by managers that may service connections from +this display. It is sent in response to either a +<function>Query ,</function> +<function>BroadcastQuery ,</function> +or +<function>ForwardQuery</function> +but does not imply a commitment to provide service +(for example, it may later decide that it has accepted enough +connections already). + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Problems/Solutions: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Problem: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +<para> +<function>Willing</function> +not received by the display. +</para> +<para> +Indication: +</para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +None if +<function>BroadcastQuery</function> +or +<function>IndirectQuery</function> +was sent, else failure to receive +<function>Willing .</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +The display should continue to send the query until a response is received. + </entry> + </row> + + + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Timeout/Retransmission policy: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Like all packets sent from the manager to the display, this packet should +never be retransmitted. + </entry> + </row> + + <row rowsep="0"> + <entry spanname="col1_on"> +<function>Unwilling</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> + <para> +Manager -> Display + </para> + <para> +Additional Fields: + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +The Hostname and Status fields as in the +<function>Willing</function> +packet. +The Status field should indicate to the user a reason +for the refusal of service. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Semantics: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +An +<function>Unwilling</function> +packet is sent by managers in response to direct +<function>Query</function> +requests (as opposed to +<function>BroadcastQuery</function> +or +<function>IndirectQuery</function> +requests) if the manager will not accept requests for management. +This is typically sent by managers that wish to only service +particular displays or that handle a limited number of displays at once. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Problems/Solutions: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Problem: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +<para> +<function>Unwilling</function> +not received by the display. +</para> +<para> +Indication: +</para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Display fails to receive +<function>Unwilling .</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +The display should continue to send +<function>Query</function> +messages until a response is received. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Timeout/Retransmission policy: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Like all packets sent from the manager to the display, this packet should +never be retransmitted. + </entry> + </row> + <row rowsep="0"> + <entry spanname="col1_on"> +<function>Request</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> + <para> +Display -> Manager + </para> + <para> +Additional Fields: + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Display Number</emphasis>: CARD16 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Specifies the index of this particular server for the host +on which the display is resident. +This value will be zero for most autonomous displays. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Connection Types</emphasis>: ARRAY16 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Specifies an array indicating the stream services accepted by the display. +If the high-order byte in a particular entry is zero, the low-order byte +corresponds to an X-protocol host family type. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Connection Addresses</emphasis>: ARRAYofARRAY8 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +For each connection type in the previous array, the corresponding entry in +this array indicates the network address of the display device. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> + <para> +<emphasis remap='I'>Authentication Name</emphasis>: ARRAY8 + </para> + <para> +<emphasis remap='I'>Authentication Data</emphasis>: ARRAY8 + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Specifies the authentication protocol that the display expects +the manager to validate itself with. The Authentication Data is +expected to contain data that the manager will interpret, modify +and use to authenticate itself. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Authorization Names</emphasis>: ARRAYofARRAY8 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Specifies which types of authorization the display supports. The +manager may decide to reject displays with which it cannot perform +authorization. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Manufacturer Display ID</emphasis>: ARRAY8 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Can be used by the manager to determine how to decrypt the +Authentication Data field in this packet. See the section below on +Manufacturer Display ID Format. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Semantics: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +A +<function>Request</function> +packet is sent by a display to a specific host to request a +session ID in preparation for a establishing a connection. If the manager +is willing to service a connection to this display, it should return an +<function>Accept</function> +packet with a valid session ID and should be ready for a subsequent +<function>Manage</function> +request. Otherwise, it should return a +<function>Decline</function> +packet. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Valid Responses: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<function>Accept ,</function> +<function>Decline</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Problems/Solutions: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Problem: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Request not received by manager. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Indication: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Display timeout waiting for response. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Display resends +<function>Request</function> +message. + </entry> + </row> + + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Problem: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Message received out of order by manager. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Indication: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +None. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Each time a +<function>Request</function> +is sent, the manager sends the Session ID +associated with the next session in the +<function>Accept .</function> +If that next session is not yet started, +the manager will simply resend with the same Session ID. +If the session is in progress, the manager will reply +with a new Session ID; in which case, the +<function>Accept</function> +will be discarded by the display. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Timeout/Retransmission policy: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Timeout after 2 seconds, exponential backoff to 32 seconds. +After no more than 126 seconds, give up and report an error to the user. + </entry> + </row> + + <row rowsep="0"> + <entry spanname="col1_on"> +<function>Accept</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> + <para> +Manager -> Display + </para> + <para> +Additional Fields: + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Session ID</emphasis>: CARD32 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Identifies the session that can be started by the manager. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> + <para> +<emphasis remap='I'>Authentication Name</emphasis>: ARRAY8 + </para> + <para> +<emphasis remap='I'>Authentication Data</emphasis>: ARRAY8 + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Is the data sent back to the display to authenticate the manager. +If the Authentication Data is not the value expected by the display, it +should terminate the protocol at this point and display an error to the user. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> + <para> +<emphasis remap='I'>Authorization Name</emphasis>: ARRAY8 + </para> + <para> +<emphasis remap='I'>Authorization Data</emphasis>: ARRAY8 + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Is the data sent to the display to indicate the type of authorization the +manager will be using in the first call to +<function>XOpenDisplay</function> +after the +<function>Manage</function> +packet is received. + </entry> + </row> + + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Semantics: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<para> +An +<function>Accept</function> +packet is sent by a manager in response to a +<function>Request</function> +packet if the manager is willing to establish a connection for the display. +The Session ID is used to identify this connection from any preceding +ones and will be used by the display in its subsequent +<function>Manage</function> +packet. +The Session ID is a 32-bit number that is incremented each time an +<function>Accept</function> +packet is sent as it must be unique over a reasonably long period of time. +</para> +<para> +If the authentication information is invalid, a +<function>Decline</function> +packet will be returned with an appropriate +<function>Status</function> +message. +</para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Problems/Solutions: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Problem: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +<function>Accept</function> +or +<function>Decline</function> +not received by display. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Indication: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Display timeout waiting for response to +<function>Request .</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Display resends +<function>Request</function> +message. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Problem: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Message received out of order by display. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Indication: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Display receives +<function>Accept</function> +after +<function>Manage</function> +has been sent. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Display discards +<function>Accept</function> +messages after it has sent a +<function>Manage</function> +message. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Timeout/Retransmission policy: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Like all packets sent from the manager to the display, this packet should +never be retransmitted. + </entry> + </row> + + <row rowsep="0"> + <entry spanname="col1_on"> +<function>Decline</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> + <para> +Manager -> Display + </para> + <para> +Additional Fields: + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Status</emphasis>: ARRAY8 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Is a human readable string indicating the reason for refusal of +service. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> + <para> +<emphasis remap='I'>Authentication Name</emphasis>: +ARRAY8 + </para> + <para> +<emphasis remap='I'>Authentication Data</emphasis>: +ARRAY8 + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Is the data sent back to the display to authenticate the manager. If the +Authentication Data is not the value expected by the display, it +should terminate the protocol at this point and display an error to the user. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Semantics: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +A +<function>Decline</function> +packet is sent by a manager in response to a +<function>Request</function> +packet if the manager is unwilling to establish a connection for the +display. +This is allowed even if the manager had responded +<function>Willing</function> +to a previous query. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Problems/Solutions: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Same as for +<function>Accept .</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Timeout/Retransmission policy: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Like all packets sent from a manager to a display, this packet should never +be retransmitted. + </entry> + </row> + + <row rowsep="0"> + <entry spanname="col1_on"> +<function>Manage</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> + <para> +Display -> Manager + </para> + <para> +Additional Fields: + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Session ID</emphasis>: CARD32 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Should contain the nonzero session ID returned in the +<function>Accept</function> +packet. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Display Number</emphasis>: CARD16 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Must match the value sent in the previous +<function>Request</function> +packet. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Display Class</emphasis>: ARRAY8 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Specifies the class of the display. +See the Display Class Format section, +which discusses the format of this field. + </entry> + </row> + + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Semantics: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +A +<function>Manage</function> +packet is sent by a display to ask the manager to begin a +session on the display. If the Session ID is correct the manager +should open a connection; otherwise, it should respond with a +<function>Refuse</function> +or +<function>Failed</function> +packet, unless the Session ID matches a currently +running session or a session that has not yet successfully opened the +display but has not given up the attempt. In this latter case, the +<function>Manage</function> +packet should be ignored. +This will work as stream connections give positive success indication +to both halves of the stream, and positive failure indication +to the connection initiator (which will eventually generate a +<function>Failed</function> +packet). + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Valid Responses: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +X connection with correct auth info, +<function>Refuse ,</function> +<function>Failed .</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Problems/Solutions: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Problem: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +<function>Manage</function> +not received by manager. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Indication: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Display timeout waiting for response. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Display resends +<function>Manage</function> +message. + </entry> + </row> + + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Problem: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +<function>Manage</function> +received out of order by manager. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Indication: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Session already in progress with matching Session ID. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +<function>Manage</function> +packet ignored. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Indication: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Session ID does not match next Session ID. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +<function>Refuse</function> +message is sent. + </entry> + </row> + + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Problem: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Display cannot be opened on selected stream. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Indication: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Display connection setup fails. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +<function>Failed</function> +message is sent including a human readable reason. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Problem: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Display open does not succeed before a second manage packet is received +because of a timeout occuring in the display. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Indication: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +<function>Manage</function> +packet received with Session ID matching the session +attempting to connect to the display. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +<function>Manage</function> +packet is ignored. As the stream connection will either +succeed, which will result in an active session, or the stream will +eventually give up hope of connecting and send a +<function>Failed</function> +packet; no response to this +<function>Manage</function> +packet is necessary. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Timeout/Retransmission policy: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Timeout after 2 seconds, exponential backoff to 32 seconds. After no more +than 126 seconds, give up and report an error to the user. + </entry> + </row> + + <row rowsep="0"> + <entry spanname="col1_on"> +<function>Refuse</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> + <para> +Manager -> Display + </para> + <para> +Additional Fields: + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Session ID</emphasis>: CARD32 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Should be set to the Session ID received in the +<function>Manage</function> +packet. + </entry> + </row> + + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Semantics: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +A +<function>Refuse</function> +packet is sent by a manager when the Session ID received in the +<function>Manage</function> +packet does not match the current Session ID. +The display should assume that it received an old +<function>Accept</function> +packet and should resend its +<function>Request</function> +packet. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Problems/Solutions: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Problem: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Error message is lost. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Indication: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Display times out waiting for +new connection, +<function>Refuse</function> +or +<function>Failed .</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Display resends +<function>Manage</function> +message. + </entry> + </row> + + + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Timeout/Retransmission policy: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Like all packets sent from a manager to a display, this packet should never be +retransmitted. + </entry> + </row> + + <row rowsep="0"> + <entry spanname="col1_on"> +<function>Failed</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> + <para> +Manager -> Display + </para> + <para> +Additional Fields: + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Session ID</emphasis>: CARD32 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Should be set to the Session ID received in the +<function>Manage</function> +packet. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Status</emphasis>: ARRAY8 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Is a human readable string indicating the reason for failure. + </entry> + </row> + + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Semantics: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +A +<function>Failed</function> +packet is sent by a manager when it has problems establishing +the initial X connection in response to the +<function>Manage</function> +packet. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Problems/Solutions + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Same as for +<function>Refuse .</function> + </entry> + </row> + + <row rowsep="0"> + <entry spanname="col1_on"> +<function>KeepAlive</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> + <para> +Display -> Manager + </para> + <para> +Additional Fields: + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Display Number</emphasis>: CARD16 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Set to the display index for the display host. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Session ID</emphasis>: CARD32 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Should be set to the Session ID received in the +<function>Manage</function> +packet during the negotiation for the current session. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Sematics: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> + <para> +A +<function>KeepAlive</function> +packet can be sent at any time during the session by a +display to discover if the manager is running. +The manager should respond with +<function>Alive</function> +whenever it receives this type of packet. + </para> + <para> +This allows the display to discover when the manager host +is no longer running. +A display is not required to send +<function>KeepAlive</function> +packets and, upon lack of receipt of +<function>Alive</function> +packets, is not required to perform any specific action. + </para> + <para> +The expected use of this packet is to terminate an active session when the +manager host or network link fails. The display should keep track of the +time since any packet has been received from the manager host and use +<function>KeepAlive</function> +packets when a substantial time has elapsed since the +most recent packet. + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Valid Responses: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<function>Alive</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Problems/Solutions: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +Problem: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Manager does not receive the packet or display does not receive the response. + </entry> + </row> + + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Indication: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +No +<function>Alive</function> +packet is returned. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Solution: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col5_on"> +Retransmit the packet with an exponential backoff; start at 2 seconds and +assume the host is not up after no less than 30 seconds. + </entry> + </row> + + <row rowsep="0"> + <entry spanname="col1_on"> +<function>Alive</function> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> + <para> +Manager -> Display + </para> + <para> +Additional Fields: + </para> + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Session Running</emphasis>: CARD8 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Indicates that the session identified by Session ID is +currently active. The value is zero if no session is active +or one if a session +is active. + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +<emphasis remap='I'>Session ID</emphasis>: CARD32 + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry></entry> + <entry spanname="col4_on"> +Specifies the ID of the currently running session; if any. +When no session is active this field should be zero. + </entry> + </row> + + + <row rowsep="0"> + <entry></entry> + <entry spanname="col2_on"> +Semantics: + </entry> + </row> + + <row rowsep="0"> + <entry></entry> + <entry></entry> + <entry spanname="col3_on"> +An +<function>Alive</function> +packet is sent in response to a +<function>KeepAlive</function> +request. +If a session is currently active on the display, the manager includes the +Session ID in the packet. The display can use this information to +determine the status of the manager. + </entry> + </row> + </tbody> + </tgroup> +</informaltable> + +</chapter> + +<chapter id="Session_Termination"> +<title>Session Termination</title> +<para> +When the session is over, the initial connection with the display (the one +that acknowledges the +<function>Manage</function> +packet) will be closed by the manager. +If only a single session was active on the display, +all other connections should be closed by the display +and the display should be reset. If multiple sessions +are active simultaneously and the display can identify which connections +belong to the terminated sesssion, those connections should be closed. +Otherwise, all connections should be closed and the display reset only when +all sessions have been terminated (that is, all initial connections closed). +</para> + +<para> +The session may also be terminated at any time by the display if the +managing host no longer responds to +<function>KeepAlive</function> +packets. +The exact time-outs for sending +<function>KeepAlive</function> +packets is not specified in this protocol as the trade off +should not be fixed between loading an otherwise idle system with spurious +<function>KeepAlive</function> +packets and not noticing that the manager host is down for a long time. +</para> +</chapter> + +<chapter id="State_Diagrams"> +<title>State Diagrams</title> +<!-- .XS --> +<!-- (SN State Diagrams --> +<!-- .XE --> +<para> +<!-- .LP --> +The following state diagrams are designed to cover all actions of both +the display and the manager. Any packet that is received out-of-sequence +will be ignored. +</para> +<para> +<!-- .LP --> +Display: +</para> + +<variablelist> + <varlistentry> + <term><emphasis remap='I'>start</emphasis>:</term> + <listitem> + <para> +User-requested connect to one host -> <emphasis remap='I'>query</emphasis> + </para> + <para> +User-requested connect to some host -> <emphasis remap='I'>broadcast</emphasis> + </para> + <para> +User-requested connect to site host-list -> <emphasis remap='I'>indirect</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>query</emphasis>:</term> + <listitem> + <para> +Send <function>Query</function> packet +-> <emphasis remap='I'>collect-query</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>collect-query</emphasis>:</term> + <listitem> + <para> +Receive <function>Willing</function> -> +<emphasis remap='I'>start-connection</emphasis> + </para> + <para> +Receive <function>Unwilling</function> -> +<emphasis remap='I'>stop-connection</emphasis> + </para> + <para> +Timeout -> <emphasis remap='I'>query</emphasis> + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><emphasis remap='I'>broadcast</emphasis>:</term> + <listitem> + <para> +Send <function>BroadcastQuery</function> packet + </para> + <para> +-> <emphasis remap='I'>collect-broadcast-query</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>collect-broadcast-query</emphasis>:</term> + <listitem> + <para> +Receive <function>Willing</function> -> +<emphasis remap='I'>update-broadcast-willing</emphasis> + </para> + <para> +User-requested connect to one host -> +<emphasis remap='I'>start-connection</emphasis> + </para> + <para> +Timeout -> <emphasis remap='I'>broadcast</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>update-broadcast-willing</emphasis>:</term> + <listitem> + <para> +Add new host to the host list presented to the user + </para> + <para> +-> <emphasis remap='I'>collect-broadcast-query</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>indirect</emphasis>:</term> + <listitem> + <para> +Send <function>IndirectQuery</function> packet + </para> + <para> +-> <emphasis remap='I'>collect-indirect-query</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>collect-indirect-query</emphasis>:</term> + <listitem> + <para> +Receive <function>Willing</function> -> +<emphasis remap='I'>update-indirect-willing</emphasis> + </para> + <para> +User-requested connect to one host -> +<emphasis remap='I'>start-connection</emphasis> + </para> + <para> +Timeout -> <emphasis remap='I'>indirect</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>update-indirect-willing</emphasis>:</term> + <listitem> + <para> +Add new host to the host list presented to the user + </para> + <para> +-> <emphasis remap='I'>collect-indirect-query</emphasis> + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><emphasis remap='I'>start-connection</emphasis>:</term> + <listitem> + <para> +Send <function>Request</function> packet + </para> + <para> +-> <emphasis remap='I'>await-request-response</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>await-request-response</emphasis>:</term> + <listitem> + <para> +Receive <function>Accept</function> -> +<emphasis remap='I'>manage</emphasis> + </para> + <para> +Receive <function>Decline</function> -> +<emphasis remap='I'>stop-connection</emphasis> + </para> + <para> +Timeout -> <emphasis remap='I'>start-connection</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>manage</emphasis>:</term> + <listitem> + <para> +Save Session ID + </para> + <para> +Send <function>Manage</function> packet with Session ID + </para> + <para> +-> <emphasis remap='I'>await-manage-response</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>await-manage-response</emphasis>:</term> + <listitem> + <para> +Receive <function>XOpenDisplay :</function> -> +<emphasis remap='I'>run-session</emphasis> + </para> + <para> +Receive <function>Refuse</function> with matching Session ID +-> <emphasis remap='I'>start-connection</emphasis> + </para> + <para> +Receive <function>Failed</function> with matching Session ID +-> <emphasis remap='I'>stop-connection</emphasis> + </para> + <para> +Timeout -> <emphasis remap='I'>manage</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>stop-connection</emphasis>:</term> + <listitem> + <para> +Display cause of termination to user + </para> + <para> +-> <emphasis remap='I'>start</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>run-session</emphasis>:</term> + <listitem> + <para> +Decide to send <function>KeepAlive</function> packet -> +<emphasis remap='I'>keep-alive</emphasis> + </para> + <para> +wait close of first display connection + </para> + <para> +-> <emphasis remap='I'>reset-display</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>keep-alive</emphasis>:</term> + <listitem> + <para> +Send <function>KeepAlive</function> packet with current Session ID + </para> + <para> +-> <emphasis remap='I'>await-alive</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>await-alive</emphasis>:</term> + <listitem> + <para> +Receive <function>Alive</function> with matching Session ID -> +<emphasis remap='I'>run-session</emphasis> + </para> + <para> +Receive <function>Alive</function> with nonmatching Session ID +or FALSE Session Running -> <emphasis remap='I'>reset-display</emphasis> + </para> + <para> +Final timeout without receiving <function>Alive</function> +packet -> <emphasis remap='I'>reset-display</emphasis> + </para> + <para> +Timeout -> <emphasis remap='I'>keep-alive</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>reset-display</emphasis>:</term> + <listitem> + <para> +(if possible) -> close all display connections associated with this session + </para> + <para> +Last session -> close all display connections + </para> + <para> +-> <emphasis remap='I'>start</emphasis> + </para> + </listitem> + </varlistentry> +</variablelist> + + +<para> +Manager: +</para> + +<variablelist> + <varlistentry> + <term><emphasis remap='I'>idle</emphasis>:</term> + <listitem> + <para> +Receive <function>Query</function> -> +<emphasis remap='I'>query-respond</emphasis> + </para> + <para> +Receive +<function>BroadcastQuery</function> +-> <emphasis remap='I'>broadcast-respond</emphasis> + </para> + <para> +Receive +<function>IndirectQuery</function> +-> <emphasis remap='I'>indirect-respond</emphasis> + </para> + <para> +Receive +<function>ForwardQuery</function> +-> <emphasis remap='I'>forward-respond</emphasis> +Receive + </para> + <para> +<function>Request</function> +-> <emphasis remap='I'>request-respond</emphasis> + </para> + <para> +Receive +<function>Manage</function> +-> <emphasis remap='I'>manage</emphasis> + </para> + <para> +An active session terminates +-> <emphasis remap='I'>finish-session</emphasis> + </para> + <para> +Receive <function>KeepAlive</function> +-> <emphasis remap='I'>send-alive</emphasis> + </para> + <para> +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>query-respond</emphasis>:</term> + <listitem> + <para> +If willing to manage -> <emphasis remap='I'>send-willing</emphasis> + </para> + <para> +-> <emphasis remap='I'>send-unwilling</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>broadcast-respond</emphasis>:</term> + <listitem> + <para> +If willing to manage -> <emphasis remap='I'>send-willing</emphasis> + </para> + <para> +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>indirect-respond</emphasis>:</term> + <listitem> + <para> +Send <function>ForwardQuery</function> +packets to all managers on redirect list + </para> + <para> +If willing to manage -> <emphasis remap='I'>send-willing</emphasis> + </para> + <para> +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>forward-respond</emphasis>:</term> + <listitem> + <para> +Decode destination address, if willing to manage -> +<emphasis remap='I'>send-willing</emphasis> + </para> + <para> +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>send-willing</emphasis>:</term> + <listitem> + <para> +Send <function>Willing</function> packet + </para> + <para> +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>send-unwilling</emphasis>:</term> + <listitem> + <para> +Send <function>Unwilling</function> packet +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>request-respond</emphasis>:</term> + <listitem> + <para> +If manager is willing to allow a session on display +-> <emphasis remap='I'>accept-session</emphasis> + </para> + <para> +-> <emphasis remap='I'>decline-session</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>accept-session</emphasis>:</term> + <listitem> + <para> +Generate Session ID and save Session ID, display address, and +display number somewhere + </para> + <para> +Send <function>Accept</function> packet + </para> + <para> +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>decline-session</emphasis>:</term> + <listitem> + <para> +Send <function>Decline</function> packet + </para> + <para> +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>manage</emphasis>:</term> + <listitem> + <para> +If Session ID matches saved Session ID -> +<emphasis remap='I'>run-session</emphasis> + </para> + <para> +If Session ID matches Session ID of session in process of +starting up, or currently active session -> +<emphasis remap='I'>idle</emphasis> + </para> + <para> +-> <emphasis remap='I'>refuse</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>refuse</emphasis>:</term> + <listitem> + <para> +Send <function>Refuse</function> packet + </para> + <para> +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>run-session</emphasis>:</term> + <listitem> + <para> +Terminate any session in progress + </para> + <para> +<function>XOpenDisplay</function> + </para> + <para> +Open display succeeds -> +<emphasis remap='I'>start-session</emphasis> + </para> + <para> +-> <emphasis remap='I'>failed</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>failed</emphasis>:</term> + <listitem> + <para> +Send <function>Failed</function> packet + </para> + <para> +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>start-session</emphasis>:</term> + <listitem> + <para> +Start a new session + </para> + <para> +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>finish-session</emphasis>:</term> + <listitem> + <para> +<function>XCloseDisplay</function> + </para> + <para> +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><emphasis remap='I'>send-alive</emphasis>:</term> + <listitem> + <para> +Send <function>Alive</function> packet containing current status + </para> + <para> +-> <emphasis remap='I'>idle</emphasis> + </para> + </listitem> + </varlistentry> +</variablelist> + +</chapter> + +<chapter id="Protocol_Encoding"> +<title>Protocol Encoding</title> +<para> +When XDMCP is implemented on top of the Internet User Datagram Protocol (UDP), +port number 177 is to be used. When using UDP over IPv4, Broadcast Query +packets are sent via UDP broadcast. When using UDP over IPv6, Broadcast Query +packets are sent via multicast, either to an address in the IANA registered +XDMCP multicast address range of +FF0<emphasis remap='I'>X</emphasis>:0:0:0:0:0:0:12B +(where the <emphasis remap='I'>X</emphasis> is replaced by a valid scope id) +or to a locally assigned +multicast address. The version number in all packets will be 1. +Packet opcodes are 16-bit integers. +</para> + +<informaltable frame="none"> + <tgroup cols='2' align='left'> + <colspec colname='c1' colsep="0"/> + <colspec colname='c2' colsep="0"/> + <thead> + <row> + <entry>Packet Name</entry> + <entry>Encoding</entry> + </row> + </thead> + <tbody> + <row rowsep="0"> + <entry>BroadcastQuery</entry> + <entry>1</entry> + </row> + <row rowsep="0"> + <entry>Query</entry> + <entry>2</entry> + </row> + <row rowsep="0"> + <entry>IndirectQuery</entry> + <entry>3</entry> + </row> + <row rowsep="0"> + <entry>ForwardQuery</entry> + <entry>4</entry> + </row> + <row rowsep="0"> + <entry>Willing</entry> + <entry>5</entry> + </row> + <row rowsep="0"> + <entry>Unwilling</entry> + <entry>6</entry> + </row> + <row rowsep="0"> + <entry>Request</entry> + <entry>7</entry> + </row> + <row rowsep="0"> + <entry>Accept</entry> + <entry>8</entry> + </row> + <row rowsep="0"> + <entry>Decline</entry> + <entry>9</entry> + </row> + <row rowsep="0"> + <entry>Manage</entry> + <entry>10</entry> + </row> + <row rowsep="0"> + <entry>Refuse</entry> + <entry>11</entry> + </row> + <row rowsep="0"> + <entry>Failed</entry> + <entry>12</entry> + </row> + <row rowsep="0"> + <entry>KeepAlive</entry> + <entry>13 +<footnote><para> +A previous version of this document incorrectly reversed the opcodes of +<emphasis role="bold">Alive</emphasis> and +<emphasis role="bold">KeepAlive</emphasis>. +</para></footnote> + </entry> + </row> + <row rowsep="0"> + <entry>Alive</entry> + <entry>14 +<footnote><para> +A previous version of this document incorrectly reversed the opcodes of +<emphasis role="bold">Alive</emphasis> and +<emphasis role="bold">KeepAlive</emphasis>. +</para></footnote> + </entry> + </row> + </tbody> + </tgroup> +</informaltable> + +<para> +Per packet information follows: +</para> + +<para> +<function>Query</function>, +<function>BroadcastQuery</function>, +<function>IndirectQuery</function> +</para> + +<literallayout class="monospaced"> + 2 CARD16 version number (always 1) + 2 CARD16 opcode (always Query, BroadcastQuery or IndirectQuery) + 2 CARD16 length + 1 CARD8 number of Authentication Names sent (m) + 2 CARD16 length of first Authentication Name (m<emphasis role="subscript">1</emphasis>) + m<emphasis role="subscript">1</emphasis> CARD8 first Authentication Name + ... Other Authentication Names +</literallayout> + +<para> +Note that these three packets are identical except for the opcode field. +</para> + +<literallayout class="monospaced"> +<function>ForwardQuery</function> + 2 CARD16 version number (always 1) + 2 CARD16 opcode (always ForwardQuery) + 2 CARD16 length + 2 CARD16 length of Client Address (m) + m CARD8 Client Address + 2 CARD16 length of Client Port (n) + n CARD8 Client Port + 1 CARD8 number of Authentication Names sent (o) + 2 CARD16 length of first Authentication Name (o<emphasis role="subscript">1</emphasis>) + o<emphasis role="subscript">1</emphasis> CARD8 first Authentication Name + ... Other Authentication Names +</literallayout> + +<literallayout class="monospaced"> +<function>Willing</function> + 2 CARD16 version number (always 1) + 2 CARD16 opcode (always Willing) + 2 CARD16 length (6 + m + n + o) + 2 CARD16 Length of Authentication Name (m) + m CARD8 Authentication Name + 2 CARD16 Hostname length (n) + n CARD8 Hostname + 2 CARD16 Status length (o) + o CARD8 Status +</literallayout> + +<literallayout class="monospaced"> +<function>Unwilling</function> + 2 CARD16 version number (always 1) + 2 CARD16 opcode (always Unwilling) + 2 CARD16 length (4 + m + n) + 2 CARD16 Hostname length (m) + m CARD8 Hostname + 2 CARD16 Status length (n) + n CARD8 Status +</literallayout> + +<literallayout class="monospaced"> +<function>Request</function> + 2 CARD16 version number (always 1) + 2 CARD16 opcode (always Request) + 2 CARD16 length + 2 CARD16 Display Number + 1 CARD8 Count of Connection Types (m) + 2xm CARD16 Connection Types + 1 CARD8 Count of Connection Addresses (n) + 2 CARD16 Length of first Connection Address (n<emphasis role="subscript">1</emphasis>) + n<emphasis role="subscript">1</emphasis> CARD8 First Connection Address + ... Other connection addresses + 2 CARD16 Length of Authentication Name (o) + o CARD8 Authentication Name + 2 CARD16 Length of Authentication Data (p) + p CARD8 Authentication Data + 1 CARD8 Count of Authorization Names (q) + 2 CARD16 Length of first Authorization Name (q<emphasis role="subscript">1</emphasis>) + q<emphasis role="subscript">1</emphasis> CARD8 First Authorization Name + ... Other authorization names + 2 CARD16 Length of Manufacturer Display ID (r) + r CARD8 Manufacturer Display ID +</literallayout> + +<literallayout class="monospaced"> +<function>Accept</function> + 2 CARD16 version number (always 1) + 2 CARD16 opcode (always Accept) + 2 CARD16 length (12 + n + m + o + p) + 4 CARD32 Session ID + 2 CARD16 Length of Authentication Name (n) + n CARD8 Authentication Name + 2 CARD16 Length of Authentication Data (m) + m CARD8 Authentication Data + 2 CARD16 Length of Authorization Name (o) + o CARD8 Authorization Name + 2 CARD16 Length of Authorization Data (p) + p CARD8 Authorization Data +</literallayout> + +<literallayout class="monospaced"> +<function>Decline</function> + 2 CARD16 version number (always 1) + 2 CARD16 opcode (always Decline) + 2 CARD16 length (6 + m + n + o) + 2 CARD16 Length of Status (m) + m CARD8 Status + 2 CARD16 Length of Authentication Name (n) + n CARD8 Authentication Name + 2 CARD16 Length of Authentication Data (o) + o CARD8 Authentication Data +</literallayout> + +<literallayout class="monospaced"> +<function>Manage</function> + 2 CARD16 version number (always 1) + 2 CARD16 opcode (always Manage) + 2 CARD16 length (8 + m) + 4 CARD32 Session ID + 2 CARD16 Display Number + 2 CARD16 Length of Display Class (m) + m CARD8 Display Class +</literallayout> + +<literallayout class="monospaced"> +<function>Refuse</function> + 2 CARD16 version number (always 1) + 2 CARD16 opcode (always Refuse) + 2 CARD16 length (4) + 4 CARD32 Session ID +</literallayout> + +<literallayout class="monospaced"> +<function>Failed</function> + 2 CARD16 version number (always 1) + 2 CARD16 opcode (always Failed) + 2 CARD16 length (6 + m) + 4 CARD32 Session ID + 2 CARD16 Length of Status (m) + m CARD8 Status +</literallayout> + +<literallayout class="monospaced"> +<function>KeepAlive</function> + 2 CARD16 version number (always 1) + 2 CARD16 opcode (always KeepAlive) + 2 CARD16 length (6) + 2 CARD16 Display Number + 4 CARD32 Session ID +</literallayout> + +<literallayout class="monospaced"> +<function>Alive</function> + 2 CARD16 version number (always 1) + 2 CARD16 opcode (always Alive) + 2 CARD16 length (5) + 1 CARD8 Session Running (0: not running 1: running) + 4 CARD32 Session ID (0: not running) +</literallayout> +</chapter> + +<chapter id="Display_Class_Format"> +<title>Display Class Format</title> +<!-- .XS --> +<!-- (SN Display Class Format --> +<!-- .XE --> +<para> +The Display Class field of the +<function>Manage</function> +packet is used by the display manager to collect common sorts of +displays into manageable groups. This field is a string encoded of +ISO-LATIN-1 characters in the following format: +</para> + +<literallayout class="monospaced"> +<emphasis remap='I'>ManufacturerID</emphasis>-<emphasis remap='I'>ModelNumber</emphasis> +</literallayout> + +<para> +Both elements of this string must exclude characters of the set +{ <function>-</function>, +<function>.</function>, +<function>:</function>, +<function>*</function>, +<function>?</function>, +<emphasis remap='I'><space></emphasis> }. +The ManufacturerID is a string that should be registered +with the X Consortium. +The ModelNumber is designed to identify characteristics of the display +within the manufacturer's product line. +This string should be documented in the users manual for the +particular device and should probably not be specifiable by the +display user to avoid unexpected configuration errors. +</para> +</chapter> + +<chapter id="Manufacturer_Display_ID_Format"> +<title>Manufacturer Display ID Format</title> +<!-- .XS --> +<!-- (SN Manufacturer Display ID Format --> +<!-- .XE --> +<para> +To authenticate the manager, the display and manager will share a private +key. +The manager, then, must be able to discover which key to use for a +particular device. +The Manufacturer Display ID field of the +<function>Request</function> +packet is intended for this purpose. Typically, the manager host will +contain a map between this number and the key. This field is intended to be +unique per display, possibly the ethernet address of the display in the form: +</para> + +<literallayout class="monospaced"> +-Ethernet-8:0:2b:a:f:d2 +</literallayout> + +<para> +It can also be a string of the form: +</para> + +<literallayout class="monospaced"> +<emphasis remap='I'>ManufacturerID</emphasis>-<emphasis remap='I'>ModelNumber</emphasis>-<emphasis remap='I'>SerialNumber</emphasis> +</literallayout> + +<para> +The ManufacturerID, ModelNumber and SerialNumber are encoded using +ISO-LATIN-1 characters, excluding { +<function>-</function>, +<function>.</function>, +<function>*</function>, +<function>?</function>, +<emphasis remap='I'><space></emphasis> } +</para> + +<para> +When the display is shipped to a customer, it should include both the +Manufacturer Display ID and the private key in the documentation set. +This information should not be modifiable by the display user. +</para> + +</chapter> + +<chapter id="Authentication"> +<title>Authentication</title> +<!-- .XS --> +<!-- (SN Authentication --> +<!-- .XE --> +<para> +In an environment where authentication is not needed, XDMCP can disable +authentication by having the display send empty Authentication Name +and Authentication Data fields in the +<function>Request</function> +packet. +In this case, the manager will not attempt to authenticate itself. +Other authentication protocols may be developed, depending on local needs. +</para> + +<para> +In an unsecure environment, the display must be able to verify that the +source of the various packets is a trusted manager. These packets will +contain authentication information. As an example of such a system, the +following discussion describes the "XDM-AUTHENTICATION-1" authentication +system. This system uses a 56-bit shared private key, and 64 bits of +authentication data. An associated example X authorization protocol +"XDM-AUTHORIZATION-1" will also be discussed. The 56-bit key is represented +as a 64-bit number in network order (big endian). This means that the first +octet in the representation will be zero. When incrementing a 64-bit value, +the 8 octets of data will be interpreted in network order (big endian). +That is, the last octet will be incremented, subsequent carries propogate +towards the first octet. +</para> + +<para> +Assumptions: +</para> + +<orderedlist> + <listitem> + <para> +The display and manager share a private key. This key could be programmed +into the display by the manufacturer and shipped with the unit. It must not +be available from the display itself, but should allow the value to be +modified in some way. The system administrator would be responsible for +managing a database of terminal keys. + </para> + </listitem> + <listitem> + <para> +The display can generate random authentication numbers. + </para> + </listitem> +</orderedlist> + +<para> +Some definitions first: +</para> + +<!-- FIXME: --> +<!-- double chk math symbols, use mathml to display them? --> +<itemizedlist> + <listitem> + <para> +{&variable.D;}<superscript>&variable.kappa;</superscript> = encryption of plain text D by key &variable.kappa; + </para> + </listitem> + <listitem> + <para> +{&variable.Delta;}*<superscript>&variable.kappa;</superscript> = decryption of crypto text &variable.Delta; with key &variable.kappa; + </para> + </listitem> + <listitem> + <para> +&variable.tau; = private key shared by display and manager + </para> + </listitem> + <listitem> + <para> +&variable.rho; = 64 bit random number generated by display + </para> + </listitem> + <listitem> + <para> +&variable.alpha; = authentication data in XDMCP packets + </para> + </listitem> + <listitem> + <para> +&variable.sigma; = per-session private key, generated by manager + </para> + </listitem> + <listitem> + <para> +&variable.beta; = authorization data + </para> + </listitem> +</itemizedlist> + +<para> +Encryption will use the Data Encryption Standard (DES, FIPS 46-3); blocks +shorter than 64 bits will be zero-filled +on the right to 64 bits. Blocks longer than 64 bits will use block chaining: +</para> +<para> +{&variable.D;}<superscript>&variable.kappa;</superscript> = {&variable.D;<subscript>1</subscript>}<superscript>&variable.kappa;</superscript> {&variable.D;<subscript>2</subscript> xor {&variable.D;<subscript>1</subscript>}<superscript>&variable.kappa;</superscript>}<superscript>&variable.kappa;</superscript> +</para> + +<para> +The display generates the first authentication data in the +<function>Request</function> +packet: +</para> + +<para> +&variable.alpha;<subscript>Request</subscript> = {&variable.rho;}<superscript>&variable.tau;</superscript> +</para> + +<para> +For the <function>Accept</function> +packet, the manager decrypts the initial message and returns +&variable.alpha;<subscript>Accept</subscript>: + +</para> + +<para> +&variable.rho; = {&variable.alpha;<subscript>Request</subscript>}*<superscript>&variable.tau;</superscript> +</para> + +<para> +&variable.alpha;<subscript>Accept</subscript> = { &variable.rho; + 1}<superscript>&variable.tau;</superscript> +</para> + +<para> +The <function>Accept</function> +packet also contains the authorization intended for use by +the X server. A description of authorization type "XDM-AUTHORIZATION-1" +follows. +</para> + +<para> +The <function>Accept</function> +packet contains the authorization name +"XDM-AUTHORIZATION-1". The authorization data is the string: +</para> +<para> +&variable.beta;<subscript>Accept</subscript> = {&variable.sigma;}<superscript>&variable.tau;</superscript> +</para> + +<para> +To create authorization information for connection setup with the X server +using the XDM-AUTHORIZATION-1 authorization protocol, the client computes the +following: +</para> +<para> +&variable.N; = X client identifier +</para> +<para> +&variable.T; = Current time in seconds on client host (32 bits) +</para> +<para> +&variable.beta; = {&variable.rho;&variable.N;&variable.T;}<superscript>&variable.sigma;</superscript> +</para> + +<para> +For TCP connections &variable.N; is 48 bits long and contains the 32-bit IPv4 address of +the client host followed by the 16-bit port number of the client socket. +Formats for other connections must be registered. +The resulting value, &variable.beta;, is 192 bits of authorization data that is sent +in the connection setup to the server. The server receives the packet, +decrypts the contents. To accept the connection, the following must hold: +</para> + +<itemizedlist> + <listitem> + <para> +&variable.rho; must match the value generated for the most recent XDMCP negotiation. + </para> + </listitem> + <listitem> + <para> +&variable.T; must be within 1200 seconds of the internally stored time. If no time +been received before, the current time is set to &variable.T;. + </para> + </listitem> + <listitem> + <para> +No packet containing the same pair (&variable.N;, &variable.T;) can have been received +in the last 1200 seconds (20 minutes). + </para> + </listitem> +</itemizedlist> +</chapter> +</book> |