diff options
Diffstat (limited to 'tools/plink/portfwd.c')
| -rw-r--r-- | tools/plink/portfwd.c | 556 |
1 files changed, 556 insertions, 0 deletions
diff --git a/tools/plink/portfwd.c b/tools/plink/portfwd.c new file mode 100644 index 000000000..e5874a697 --- /dev/null +++ b/tools/plink/portfwd.c @@ -0,0 +1,556 @@ +/*
+ * SSH port forwarding.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "putty.h"
+#include "ssh.h"
+
+#ifndef FALSE
+#define FALSE 0
+#endif
+#ifndef TRUE
+#define TRUE 1
+#endif
+
+struct PFwdPrivate {
+ const struct plug_function_table *fn;
+ /* the above variable absolutely *must* be the first in this structure */
+ void *c; /* (channel) data used by ssh.c */
+ void *backhandle; /* instance of SSH backend itself */
+ /* Note that backhandle need not be filled in if c is non-NULL */
+ Socket s;
+ int throttled, throttle_override;
+ int ready;
+ /*
+ * `dynamic' does double duty. It's set to 0 for an ordinary
+ * forwarded port, and nonzero for SOCKS-style dynamic port
+ * forwarding; but it also represents the state of the SOCKS
+ * exchange.
+ */
+ int dynamic;
+ /*
+ * `hostname' and `port' are the real hostname and port, once
+ * we know what we're connecting to; they're unused for this
+ * purpose while conducting a local SOCKS exchange, which means
+ * we can also use them as a buffer and pointer for reading
+ * data from the SOCKS client.
+ */
+ char hostname[256+8];
+ int port;
+ /*
+ * When doing dynamic port forwarding, we can receive
+ * connection data before we are actually able to send it; so
+ * we may have to temporarily hold some in a dynamically
+ * allocated buffer here.
+ */
+ void *buffer;
+ int buflen;
+};
+
+static void pfd_log(Plug plug, int type, SockAddr addr, int port,
+ const char *error_msg, int error_code)
+{
+ /* we have to dump these since we have no interface to logging.c */
+}
+
+static int pfd_closing(Plug plug, const char *error_msg, int error_code,
+ int calling_back)
+{
+ struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
+
+ /*
+ * We have no way to communicate down the forwarded connection,
+ * so if an error occurred on the socket, we just ignore it
+ * and treat it like a proper close.
+ */
+ if (pr->c)
+ sshfwd_close(pr->c);
+ pfd_close(pr->s);
+ return 1;
+}
+
+static int pfd_receive(Plug plug, int urgent, char *data, int len)
+{
+ struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
+ if (pr->dynamic) {
+ while (len--) {
+ /*
+ * Throughout SOCKS negotiation, "hostname" is re-used as a
+ * random protocol buffer with "port" storing the length.
+ */
+ if (pr->port >= lenof(pr->hostname)) {
+ /* Request too long. */
+ if ((pr->dynamic >> 12) == 4) {
+ /* Send back a SOCKS 4 error before closing. */
+ char data[8];
+ memset(data, 0, sizeof(data));
+ data[1] = 91; /* generic `request rejected' */
+ sk_write(pr->s, data, 8);
+ }
+ pfd_close(pr->s);
+ return 1;
+ }
+ pr->hostname[pr->port++] = *data++;
+
+ /*
+ * Now check what's in the buffer to see if it's a
+ * valid and complete message in the SOCKS exchange.
+ */
+ if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) &&
+ pr->hostname[0] == 4) {
+ /*
+ * SOCKS 4.
+ */
+ if (pr->dynamic == 1)
+ pr->dynamic = 0x4000;
+ if (pr->port < 2) continue;/* don't have command code yet */
+ if (pr->hostname[1] != 1) {
+ /* Not CONNECT. */
+ /* Send back a SOCKS 4 error before closing. */
+ char data[8];
+ memset(data, 0, sizeof(data));
+ data[1] = 91; /* generic `request rejected' */
+ sk_write(pr->s, data, 8);
+ pfd_close(pr->s);
+ return 1;
+ }
+ if (pr->port <= 8) continue; /* haven't started user/hostname */
+ if (pr->hostname[pr->port-1] != 0)
+ continue; /* haven't _finished_ user/hostname */
+ /*
+ * Now we have a full SOCKS 4 request. Check it to
+ * see if it's a SOCKS 4A request.
+ */
+ if (pr->hostname[4] == 0 && pr->hostname[5] == 0 &&
+ pr->hostname[6] == 0 && pr->hostname[7] != 0) {
+ /*
+ * It's SOCKS 4A. So if we haven't yet
+ * collected the host name, we should continue
+ * waiting for data in order to do so; if we
+ * have, we can go ahead.
+ */
+ int len;
+ if (pr->dynamic == 0x4000) {
+ pr->dynamic = 0x4001;
+ pr->port = 8; /* reset buffer to overwrite name */
+ continue;
+ }
+ pr->hostname[0] = 0; /* reply version code */
+ pr->hostname[1] = 90; /* request granted */
+ sk_write(pr->s, pr->hostname, 8);
+ len= pr->port - 8;
+ pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
+ memmove(pr->hostname, pr->hostname + 8, len);
+ goto connect;
+ } else {
+ /*
+ * It's SOCKS 4, which means we should format
+ * the IP address into the hostname string and
+ * then just go.
+ */
+ pr->hostname[0] = 0; /* reply version code */
+ pr->hostname[1] = 90; /* request granted */
+ sk_write(pr->s, pr->hostname, 8);
+ pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
+ sprintf(pr->hostname, "%d.%d.%d.%d",
+ (unsigned char)pr->hostname[4],
+ (unsigned char)pr->hostname[5],
+ (unsigned char)pr->hostname[6],
+ (unsigned char)pr->hostname[7]);
+ goto connect;
+ }
+ }
+
+ if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) &&
+ pr->hostname[0] == 5) {
+ /*
+ * SOCKS 5.
+ */
+ if (pr->dynamic == 1)
+ pr->dynamic = 0x5000;
+
+ if (pr->dynamic == 0x5000) {
+ int i, method;
+ char data[2];
+ /*
+ * We're receiving a set of method identifiers.
+ */
+ if (pr->port < 2) continue;/* no method count yet */
+ if (pr->port < 2 + (unsigned char)pr->hostname[1])
+ continue; /* no methods yet */
+ method = 0xFF; /* invalid */
+ for (i = 0; i < (unsigned char)pr->hostname[1]; i++)
+ if (pr->hostname[2+i] == 0) {
+ method = 0;/* no auth */
+ break;
+ }
+ data[0] = 5;
+ data[1] = method;
+ sk_write(pr->s, data, 2);
+ pr->dynamic = 0x5001;
+ pr->port = 0; /* re-empty the buffer */
+ continue;
+ }
+
+ if (pr->dynamic == 0x5001) {
+ /*
+ * We're receiving a SOCKS request.
+ */
+ unsigned char reply[10]; /* SOCKS5 atyp=1 reply */
+ int atype, alen = 0;
+
+ /*
+ * Pre-fill reply packet.
+ * In all cases, we set BND.{HOST,ADDR} to 0.0.0.0:0
+ * (atyp=1) in the reply; if we succeed, we don't know
+ * the right answers, and if we fail, they should be
+ * ignored.
+ */
+ memset(reply, 0, lenof(reply));
+ reply[0] = 5; /* VER */
+ reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */
+
+ if (pr->port < 6) continue;
+ atype = (unsigned char)pr->hostname[3];
+ if (atype == 1) /* IPv4 address */
+ alen = 4;
+ if (atype == 4) /* IPv6 address */
+ alen = 16;
+ if (atype == 3) /* domain name has leading length */
+ alen = 1 + (unsigned char)pr->hostname[4];
+ if (pr->port < 6 + alen) continue;
+ if (pr->hostname[1] != 1 || pr->hostname[2] != 0) {
+ /* Not CONNECT or reserved field nonzero - error */
+ reply[1] = 1; /* generic failure */
+ sk_write(pr->s, (char *) reply, lenof(reply));
+ pfd_close(pr->s);
+ return 1;
+ }
+ /*
+ * Now we have a viable connect request. Switch
+ * on atype.
+ */
+ pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen);
+ if (atype == 1) {
+ /* REP=0 (success) already */
+ sk_write(pr->s, (char *) reply, lenof(reply));
+ sprintf(pr->hostname, "%d.%d.%d.%d",
+ (unsigned char)pr->hostname[4],
+ (unsigned char)pr->hostname[5],
+ (unsigned char)pr->hostname[6],
+ (unsigned char)pr->hostname[7]);
+ goto connect;
+ } else if (atype == 3) {
+ /* REP=0 (success) already */
+ sk_write(pr->s, (char *) reply, lenof(reply));
+ memmove(pr->hostname, pr->hostname + 5, alen-1);
+ pr->hostname[alen-1] = '\0';
+ goto connect;
+ } else {
+ /*
+ * Unknown address type. (FIXME: support IPv6!)
+ */
+ reply[1] = 8; /* atype not supported */
+ sk_write(pr->s, (char *) reply, lenof(reply));
+ pfd_close(pr->s);
+ return 1;
+ }
+ }
+ }
+
+ /*
+ * If we get here without either having done `continue'
+ * or `goto connect', it must be because there is no
+ * sensible interpretation of what's in our buffer. So
+ * close the connection rudely.
+ */
+ pfd_close(pr->s);
+ return 1;
+ }
+ return 1;
+
+ /*
+ * We come here when we're ready to make an actual
+ * connection.
+ */
+ connect:
+
+ /*
+ * Freeze the socket until the SSH server confirms the
+ * connection.
+ */
+ sk_set_frozen(pr->s, 1);
+
+ pr->c = new_sock_channel(pr->backhandle, pr->s);
+ if (pr->c == NULL) {
+ pfd_close(pr->s);
+ return 1;
+ } else {
+ /* asks to forward to the specified host/port for this */
+ ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
+ }
+ pr->dynamic = 0;
+
+ /*
+ * If there's any data remaining in our current buffer,
+ * save it to be sent on pfd_confirm().
+ */
+ if (len > 0) {
+ pr->buffer = snewn(len, char);
+ memcpy(pr->buffer, data, len);
+ pr->buflen = len;
+ }
+ }
+ if (pr->ready) {
+ if (sshfwd_write(pr->c, data, len) > 0) {
+ pr->throttled = 1;
+ sk_set_frozen(pr->s, 1);
+ }
+ }
+ return 1;
+}
+
+static void pfd_sent(Plug plug, int bufsize)
+{
+ struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
+
+ if (pr->c)
+ sshfwd_unthrottle(pr->c, bufsize);
+}
+
+/*
+ * Called when receiving a PORT OPEN from the server
+ */
+const char *pfd_newconnect(Socket *s, char *hostname, int port,
+ void *c, const Config *cfg, int addressfamily)
+{
+ static const struct plug_function_table fn_table = {
+ pfd_log,
+ pfd_closing,
+ pfd_receive,
+ pfd_sent,
+ NULL
+ };
+
+ SockAddr addr;
+ const char *err;
+ char *dummy_realhost;
+ struct PFwdPrivate *pr;
+
+ /*
+ * Try to find host.
+ */
+ addr = name_lookup(hostname, port, &dummy_realhost, cfg, addressfamily);
+ if ((err = sk_addr_error(addr)) != NULL) {
+ sk_addr_free(addr);
+ return err;
+ }
+
+ /*
+ * Open socket.
+ */
+ pr = snew(struct PFwdPrivate);
+ pr->buffer = NULL;
+ pr->fn = &fn_table;
+ pr->throttled = pr->throttle_override = 0;
+ pr->ready = 1;
+ pr->c = c;
+ pr->backhandle = NULL; /* we shouldn't need this */
+ pr->dynamic = 0;
+
+ pr->s = *s = new_connection(addr, dummy_realhost, port,
+ 0, 1, 0, 0, (Plug) pr, cfg);
+ if ((err = sk_socket_error(*s)) != NULL) {
+ sfree(pr);
+ return err;
+ }
+
+ sk_set_private_ptr(*s, pr);
+ return NULL;
+}
+
+/*
+ called when someone connects to the local port
+ */
+
+static int pfd_accepting(Plug p, OSSocket sock)
+{
+ static const struct plug_function_table fn_table = {
+ pfd_log,
+ pfd_closing,
+ pfd_receive,
+ pfd_sent,
+ NULL
+ };
+ struct PFwdPrivate *pr, *org;
+ Socket s;
+ const char *err;
+
+ org = (struct PFwdPrivate *)p;
+ pr = snew(struct PFwdPrivate);
+ pr->buffer = NULL;
+ pr->fn = &fn_table;
+
+ pr->c = NULL;
+ pr->backhandle = org->backhandle;
+
+ pr->s = s = sk_register(sock, (Plug) pr);
+ if ((err = sk_socket_error(s)) != NULL) {
+ sfree(pr);
+ return err != NULL;
+ }
+
+ sk_set_private_ptr(s, pr);
+
+ pr->throttled = pr->throttle_override = 0;
+ pr->ready = 0;
+
+ if (org->dynamic) {
+ pr->dynamic = 1;
+ pr->port = 0; /* "hostname" buffer is so far empty */
+ sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */
+ } else {
+ pr->dynamic = 0;
+ strcpy(pr->hostname, org->hostname);
+ pr->port = org->port;
+ pr->c = new_sock_channel(org->backhandle, s);
+
+ if (pr->c == NULL) {
+ sfree(pr);
+ return 1;
+ } else {
+ /* asks to forward to the specified host/port for this */
+ ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
+ }
+ }
+
+ return 0;
+}
+
+
+/* Add a new forwarding from port -> desthost:destport
+ sets up a listener on the local machine on (srcaddr:)port
+ */
+const char *pfd_addforward(char *desthost, int destport, char *srcaddr,
+ int port, void *backhandle, const Config *cfg,
+ void **sockdata, int address_family)
+{
+ static const struct plug_function_table fn_table = {
+ pfd_log,
+ pfd_closing,
+ pfd_receive, /* should not happen... */
+ pfd_sent, /* also should not happen */
+ pfd_accepting
+ };
+
+ const char *err;
+ struct PFwdPrivate *pr;
+ Socket s;
+
+ /*
+ * Open socket.
+ */
+ pr = snew(struct PFwdPrivate);
+ pr->buffer = NULL;
+ pr->fn = &fn_table;
+ pr->c = NULL;
+ if (desthost) {
+ strcpy(pr->hostname, desthost);
+ pr->port = destport;
+ pr->dynamic = 0;
+ } else
+ pr->dynamic = 1;
+ pr->throttled = pr->throttle_override = 0;
+ pr->ready = 0;
+ pr->backhandle = backhandle;
+
+ pr->s = s = new_listener(srcaddr, port, (Plug) pr,
+ !cfg->lport_acceptall, cfg, address_family);
+ if ((err = sk_socket_error(s)) != NULL) {
+ sfree(pr);
+ return err;
+ }
+
+ sk_set_private_ptr(s, pr);
+
+ *sockdata = (void *)s;
+
+ return NULL;
+}
+
+void pfd_close(Socket s)
+{
+ struct PFwdPrivate *pr;
+
+ if (!s)
+ return;
+
+ pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
+
+ sfree(pr->buffer);
+ sfree(pr);
+
+ sk_close(s);
+}
+
+/*
+ * Terminate a listener.
+ */
+void pfd_terminate(void *sv)
+{
+ pfd_close((Socket)sv);
+}
+
+void pfd_unthrottle(Socket s)
+{
+ struct PFwdPrivate *pr;
+ if (!s)
+ return;
+ pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
+
+ pr->throttled = 0;
+ sk_set_frozen(s, pr->throttled || pr->throttle_override);
+}
+
+void pfd_override_throttle(Socket s, int enable)
+{
+ struct PFwdPrivate *pr;
+ if (!s)
+ return;
+ pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
+
+ pr->throttle_override = enable;
+ sk_set_frozen(s, pr->throttled || pr->throttle_override);
+}
+
+/*
+ * Called to send data down the raw connection.
+ */
+int pfd_send(Socket s, char *data, int len)
+{
+ if (s == NULL)
+ return 0;
+ return sk_write(s, data, len);
+}
+
+
+void pfd_confirm(Socket s)
+{
+ struct PFwdPrivate *pr;
+
+ if (s == NULL)
+ return;
+
+ pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
+ pr->ready = 1;
+ sk_set_frozen(s, 0);
+ sk_write(s, NULL, 0);
+ if (pr->buffer) {
+ sshfwd_write(pr->c, pr->buffer, pr->buflen);
+ sfree(pr->buffer);
+ pr->buffer = NULL;
+ }
+}
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