diff options
Diffstat (limited to 'tools/plink/telnet.c')
| -rw-r--r-- | tools/plink/telnet.c | 1091 |
1 files changed, 1091 insertions, 0 deletions
diff --git a/tools/plink/telnet.c b/tools/plink/telnet.c new file mode 100644 index 000000000..8fbe88679 --- /dev/null +++ b/tools/plink/telnet.c @@ -0,0 +1,1091 @@ +/*
+ * Telnet backend.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "putty.h"
+
+#ifndef FALSE
+#define FALSE 0
+#endif
+#ifndef TRUE
+#define TRUE 1
+#endif
+
+#define IAC 255 /* interpret as command: */
+#define DONT 254 /* you are not to use option */
+#define DO 253 /* please, you use option */
+#define WONT 252 /* I won't use option */
+#define WILL 251 /* I will use option */
+#define SB 250 /* interpret as subnegotiation */
+#define SE 240 /* end sub negotiation */
+
+#define GA 249 /* you may reverse the line */
+#define EL 248 /* erase the current line */
+#define EC 247 /* erase the current character */
+#define AYT 246 /* are you there */
+#define AO 245 /* abort output--but let prog finish */
+#define IP 244 /* interrupt process--permanently */
+#define BREAK 243 /* break */
+#define DM 242 /* data mark--for connect. cleaning */
+#define NOP 241 /* nop */
+#define EOR 239 /* end of record (transparent mode) */
+#define ABORT 238 /* Abort process */
+#define SUSP 237 /* Suspend process */
+#define xEOF 236 /* End of file: EOF is already used... */
+
+#define TELOPTS(X) \
+ X(BINARY, 0) /* 8-bit data path */ \
+ X(ECHO, 1) /* echo */ \
+ X(RCP, 2) /* prepare to reconnect */ \
+ X(SGA, 3) /* suppress go ahead */ \
+ X(NAMS, 4) /* approximate message size */ \
+ X(STATUS, 5) /* give status */ \
+ X(TM, 6) /* timing mark */ \
+ X(RCTE, 7) /* remote controlled transmission and echo */ \
+ X(NAOL, 8) /* negotiate about output line width */ \
+ X(NAOP, 9) /* negotiate about output page size */ \
+ X(NAOCRD, 10) /* negotiate about CR disposition */ \
+ X(NAOHTS, 11) /* negotiate about horizontal tabstops */ \
+ X(NAOHTD, 12) /* negotiate about horizontal tab disposition */ \
+ X(NAOFFD, 13) /* negotiate about formfeed disposition */ \
+ X(NAOVTS, 14) /* negotiate about vertical tab stops */ \
+ X(NAOVTD, 15) /* negotiate about vertical tab disposition */ \
+ X(NAOLFD, 16) /* negotiate about output LF disposition */ \
+ X(XASCII, 17) /* extended ascic character set */ \
+ X(LOGOUT, 18) /* force logout */ \
+ X(BM, 19) /* byte macro */ \
+ X(DET, 20) /* data entry terminal */ \
+ X(SUPDUP, 21) /* supdup protocol */ \
+ X(SUPDUPOUTPUT, 22) /* supdup output */ \
+ X(SNDLOC, 23) /* send location */ \
+ X(TTYPE, 24) /* terminal type */ \
+ X(EOR, 25) /* end or record */ \
+ X(TUID, 26) /* TACACS user identification */ \
+ X(OUTMRK, 27) /* output marking */ \
+ X(TTYLOC, 28) /* terminal location number */ \
+ X(3270REGIME, 29) /* 3270 regime */ \
+ X(X3PAD, 30) /* X.3 PAD */ \
+ X(NAWS, 31) /* window size */ \
+ X(TSPEED, 32) /* terminal speed */ \
+ X(LFLOW, 33) /* remote flow control */ \
+ X(LINEMODE, 34) /* Linemode option */ \
+ X(XDISPLOC, 35) /* X Display Location */ \
+ X(OLD_ENVIRON, 36) /* Old - Environment variables */ \
+ X(AUTHENTICATION, 37) /* Authenticate */ \
+ X(ENCRYPT, 38) /* Encryption option */ \
+ X(NEW_ENVIRON, 39) /* New - Environment variables */ \
+ X(TN3270E, 40) /* TN3270 enhancements */ \
+ X(XAUTH, 41) \
+ X(CHARSET, 42) /* Character set */ \
+ X(RSP, 43) /* Remote serial port */ \
+ X(COM_PORT_OPTION, 44) /* Com port control */ \
+ X(SLE, 45) /* Suppress local echo */ \
+ X(STARTTLS, 46) /* Start TLS */ \
+ X(KERMIT, 47) /* Automatic Kermit file transfer */ \
+ X(SEND_URL, 48) \
+ X(FORWARD_X, 49) \
+ X(PRAGMA_LOGON, 138) \
+ X(SSPI_LOGON, 139) \
+ X(PRAGMA_HEARTBEAT, 140) \
+ X(EXOPL, 255) /* extended-options-list */
+
+#define telnet_enum(x,y) TELOPT_##x = y,
+enum { TELOPTS(telnet_enum) dummy=0 };
+#undef telnet_enum
+
+#define TELQUAL_IS 0 /* option is... */
+#define TELQUAL_SEND 1 /* send option */
+#define TELQUAL_INFO 2 /* ENVIRON: informational version of IS */
+#define BSD_VAR 1
+#define BSD_VALUE 0
+#define RFC_VAR 0
+#define RFC_VALUE 1
+
+#define CR 13
+#define LF 10
+#define NUL 0
+
+#define iswritable(x) \
+ ( (x) != IAC && \
+ (telnet->opt_states[o_we_bin.index] == ACTIVE || (x) != CR))
+
+static char *telopt(int opt)
+{
+#define telnet_str(x,y) case TELOPT_##x: return #x;
+ switch (opt) {
+ TELOPTS(telnet_str)
+ default:
+ return "<unknown>";
+ }
+#undef telnet_str
+}
+
+static void telnet_size(void *handle, int width, int height);
+
+struct Opt {
+ int send; /* what we initially send */
+ int nsend; /* -ve send if requested to stop it */
+ int ack, nak; /* +ve and -ve acknowledgements */
+ int option; /* the option code */
+ int index; /* index into telnet->opt_states[] */
+ enum {
+ REQUESTED, ACTIVE, INACTIVE, REALLY_INACTIVE
+ } initial_state;
+};
+
+enum {
+ OPTINDEX_NAWS,
+ OPTINDEX_TSPEED,
+ OPTINDEX_TTYPE,
+ OPTINDEX_OENV,
+ OPTINDEX_NENV,
+ OPTINDEX_ECHO,
+ OPTINDEX_WE_SGA,
+ OPTINDEX_THEY_SGA,
+ OPTINDEX_WE_BIN,
+ OPTINDEX_THEY_BIN,
+ NUM_OPTS
+};
+
+static const struct Opt o_naws =
+ { WILL, WONT, DO, DONT, TELOPT_NAWS, OPTINDEX_NAWS, REQUESTED };
+static const struct Opt o_tspeed =
+ { WILL, WONT, DO, DONT, TELOPT_TSPEED, OPTINDEX_TSPEED, REQUESTED };
+static const struct Opt o_ttype =
+ { WILL, WONT, DO, DONT, TELOPT_TTYPE, OPTINDEX_TTYPE, REQUESTED };
+static const struct Opt o_oenv =
+ { WILL, WONT, DO, DONT, TELOPT_OLD_ENVIRON, OPTINDEX_OENV, INACTIVE };
+static const struct Opt o_nenv =
+ { WILL, WONT, DO, DONT, TELOPT_NEW_ENVIRON, OPTINDEX_NENV, REQUESTED };
+static const struct Opt o_echo =
+ { DO, DONT, WILL, WONT, TELOPT_ECHO, OPTINDEX_ECHO, REQUESTED };
+static const struct Opt o_we_sga =
+ { WILL, WONT, DO, DONT, TELOPT_SGA, OPTINDEX_WE_SGA, REQUESTED };
+static const struct Opt o_they_sga =
+ { DO, DONT, WILL, WONT, TELOPT_SGA, OPTINDEX_THEY_SGA, REQUESTED };
+static const struct Opt o_we_bin =
+ { WILL, WONT, DO, DONT, TELOPT_BINARY, OPTINDEX_WE_BIN, INACTIVE };
+static const struct Opt o_they_bin =
+ { DO, DONT, WILL, WONT, TELOPT_BINARY, OPTINDEX_THEY_BIN, INACTIVE };
+
+static const struct Opt *const opts[] = {
+ &o_naws, &o_tspeed, &o_ttype, &o_oenv, &o_nenv, &o_echo,
+ &o_we_sga, &o_they_sga, &o_we_bin, &o_they_bin, NULL
+};
+
+typedef struct telnet_tag {
+ const struct plug_function_table *fn;
+ /* the above field _must_ be first in the structure */
+
+ Socket s;
+
+ void *frontend;
+ void *ldisc;
+ int term_width, term_height;
+
+ int opt_states[NUM_OPTS];
+
+ int echoing, editing;
+ int activated;
+ int bufsize;
+ int in_synch;
+ int sb_opt, sb_len;
+ unsigned char *sb_buf;
+ int sb_size;
+
+ enum {
+ TOP_LEVEL, SEENIAC, SEENWILL, SEENWONT, SEENDO, SEENDONT,
+ SEENSB, SUBNEGOT, SUBNEG_IAC, SEENCR
+ } state;
+
+ Config cfg;
+
+ Pinger pinger;
+} *Telnet;
+
+#define TELNET_MAX_BACKLOG 4096
+
+#define SB_DELTA 1024
+
+static void c_write(Telnet telnet, char *buf, int len)
+{
+ int backlog;
+ backlog = from_backend(telnet->frontend, 0, buf, len);
+ sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
+}
+
+static void log_option(Telnet telnet, char *sender, int cmd, int option)
+{
+ char *buf;
+ /*
+ * The strange-looking "<?""?>" below is there to avoid a
+ * trigraph - a double question mark followed by > maps to a
+ * closing brace character!
+ */
+ buf = dupprintf("%s:\t%s %s", sender,
+ (cmd == WILL ? "WILL" : cmd == WONT ? "WONT" :
+ cmd == DO ? "DO" : cmd == DONT ? "DONT" : "<?""?>"),
+ telopt(option));
+ logevent(telnet->frontend, buf);
+ sfree(buf);
+}
+
+static void send_opt(Telnet telnet, int cmd, int option)
+{
+ unsigned char b[3];
+
+ b[0] = IAC;
+ b[1] = cmd;
+ b[2] = option;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 3);
+ log_option(telnet, "client", cmd, option);
+}
+
+static void deactivate_option(Telnet telnet, const struct Opt *o)
+{
+ if (telnet->opt_states[o->index] == REQUESTED ||
+ telnet->opt_states[o->index] == ACTIVE)
+ send_opt(telnet, o->nsend, o->option);
+ telnet->opt_states[o->index] = REALLY_INACTIVE;
+}
+
+/*
+ * Generate side effects of enabling or disabling an option.
+ */
+static void option_side_effects(Telnet telnet, const struct Opt *o, int enabled)
+{
+ if (o->option == TELOPT_ECHO && o->send == DO)
+ telnet->echoing = !enabled;
+ else if (o->option == TELOPT_SGA && o->send == DO)
+ telnet->editing = !enabled;
+ if (telnet->ldisc) /* cause ldisc to notice the change */
+ ldisc_send(telnet->ldisc, NULL, 0, 0);
+
+ /* Ensure we get the minimum options */
+ if (!telnet->activated) {
+ if (telnet->opt_states[o_echo.index] == INACTIVE) {
+ telnet->opt_states[o_echo.index] = REQUESTED;
+ send_opt(telnet, o_echo.send, o_echo.option);
+ }
+ if (telnet->opt_states[o_we_sga.index] == INACTIVE) {
+ telnet->opt_states[o_we_sga.index] = REQUESTED;
+ send_opt(telnet, o_we_sga.send, o_we_sga.option);
+ }
+ if (telnet->opt_states[o_they_sga.index] == INACTIVE) {
+ telnet->opt_states[o_they_sga.index] = REQUESTED;
+ send_opt(telnet, o_they_sga.send, o_they_sga.option);
+ }
+ telnet->activated = TRUE;
+ }
+}
+
+static void activate_option(Telnet telnet, const struct Opt *o)
+{
+ if (o->send == WILL && o->option == TELOPT_NAWS)
+ telnet_size(telnet, telnet->term_width, telnet->term_height);
+ if (o->send == WILL &&
+ (o->option == TELOPT_NEW_ENVIRON ||
+ o->option == TELOPT_OLD_ENVIRON)) {
+ /*
+ * We may only have one kind of ENVIRON going at a time.
+ * This is a hack, but who cares.
+ */
+ deactivate_option(telnet, o->option ==
+ TELOPT_NEW_ENVIRON ? &o_oenv : &o_nenv);
+ }
+ option_side_effects(telnet, o, 1);
+}
+
+static void refused_option(Telnet telnet, const struct Opt *o)
+{
+ if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
+ telnet->opt_states[o_oenv.index] == INACTIVE) {
+ send_opt(telnet, WILL, TELOPT_OLD_ENVIRON);
+ telnet->opt_states[o_oenv.index] = REQUESTED;
+ }
+ option_side_effects(telnet, o, 0);
+}
+
+static void proc_rec_opt(Telnet telnet, int cmd, int option)
+{
+ const struct Opt *const *o;
+
+ log_option(telnet, "server", cmd, option);
+ for (o = opts; *o; o++) {
+ if ((*o)->option == option && (*o)->ack == cmd) {
+ switch (telnet->opt_states[(*o)->index]) {
+ case REQUESTED:
+ telnet->opt_states[(*o)->index] = ACTIVE;
+ activate_option(telnet, *o);
+ break;
+ case ACTIVE:
+ break;
+ case INACTIVE:
+ telnet->opt_states[(*o)->index] = ACTIVE;
+ send_opt(telnet, (*o)->send, option);
+ activate_option(telnet, *o);
+ break;
+ case REALLY_INACTIVE:
+ send_opt(telnet, (*o)->nsend, option);
+ break;
+ }
+ return;
+ } else if ((*o)->option == option && (*o)->nak == cmd) {
+ switch (telnet->opt_states[(*o)->index]) {
+ case REQUESTED:
+ telnet->opt_states[(*o)->index] = INACTIVE;
+ refused_option(telnet, *o);
+ break;
+ case ACTIVE:
+ telnet->opt_states[(*o)->index] = INACTIVE;
+ send_opt(telnet, (*o)->nsend, option);
+ option_side_effects(telnet, *o, 0);
+ break;
+ case INACTIVE:
+ case REALLY_INACTIVE:
+ break;
+ }
+ return;
+ }
+ }
+ /*
+ * If we reach here, the option was one we weren't prepared to
+ * cope with. If the request was positive (WILL or DO), we send
+ * a negative ack to indicate refusal. If the request was
+ * negative (WONT / DONT), we must do nothing.
+ */
+ if (cmd == WILL || cmd == DO)
+ send_opt(telnet, (cmd == WILL ? DONT : WONT), option);
+}
+
+static void process_subneg(Telnet telnet)
+{
+ unsigned char b[2048], *p, *q;
+ int var, value, n;
+ char *e;
+
+ switch (telnet->sb_opt) {
+ case TELOPT_TSPEED:
+ if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
+ char *logbuf;
+ b[0] = IAC;
+ b[1] = SB;
+ b[2] = TELOPT_TSPEED;
+ b[3] = TELQUAL_IS;
+ strcpy((char *)(b + 4), telnet->cfg.termspeed);
+ n = 4 + strlen(telnet->cfg.termspeed);
+ b[n] = IAC;
+ b[n + 1] = SE;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, n + 2);
+ logevent(telnet->frontend, "server:\tSB TSPEED SEND");
+ logbuf = dupprintf("client:\tSB TSPEED IS %s", telnet->cfg.termspeed);
+ logevent(telnet->frontend, logbuf);
+ sfree(logbuf);
+ } else
+ logevent(telnet->frontend, "server:\tSB TSPEED <something weird>");
+ break;
+ case TELOPT_TTYPE:
+ if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
+ char *logbuf;
+ b[0] = IAC;
+ b[1] = SB;
+ b[2] = TELOPT_TTYPE;
+ b[3] = TELQUAL_IS;
+ for (n = 0; telnet->cfg.termtype[n]; n++)
+ b[n + 4] = (telnet->cfg.termtype[n] >= 'a'
+ && telnet->cfg.termtype[n] <=
+ 'z' ? telnet->cfg.termtype[n] + 'A' -
+ 'a' : telnet->cfg.termtype[n]);
+ b[n + 4] = IAC;
+ b[n + 5] = SE;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, n + 6);
+ b[n + 4] = 0;
+ logevent(telnet->frontend, "server:\tSB TTYPE SEND");
+ logbuf = dupprintf("client:\tSB TTYPE IS %s", b + 4);
+ logevent(telnet->frontend, logbuf);
+ sfree(logbuf);
+ } else
+ logevent(telnet->frontend, "server:\tSB TTYPE <something weird>\r\n");
+ break;
+ case TELOPT_OLD_ENVIRON:
+ case TELOPT_NEW_ENVIRON:
+ p = telnet->sb_buf;
+ q = p + telnet->sb_len;
+ if (p < q && *p == TELQUAL_SEND) {
+ char *logbuf;
+ p++;
+ logbuf = dupprintf("server:\tSB %s SEND", telopt(telnet->sb_opt));
+ logevent(telnet->frontend, logbuf);
+ sfree(logbuf);
+ if (telnet->sb_opt == TELOPT_OLD_ENVIRON) {
+ if (telnet->cfg.rfc_environ) {
+ value = RFC_VALUE;
+ var = RFC_VAR;
+ } else {
+ value = BSD_VALUE;
+ var = BSD_VAR;
+ }
+ /*
+ * Try to guess the sense of VAR and VALUE.
+ */
+ while (p < q) {
+ if (*p == RFC_VAR) {
+ value = RFC_VALUE;
+ var = RFC_VAR;
+ } else if (*p == BSD_VAR) {
+ value = BSD_VALUE;
+ var = BSD_VAR;
+ }
+ p++;
+ }
+ } else {
+ /*
+ * With NEW_ENVIRON, the sense of VAR and VALUE
+ * isn't in doubt.
+ */
+ value = RFC_VALUE;
+ var = RFC_VAR;
+ }
+ b[0] = IAC;
+ b[1] = SB;
+ b[2] = telnet->sb_opt;
+ b[3] = TELQUAL_IS;
+ n = 4;
+ e = telnet->cfg.environmt;
+ while (*e) {
+ b[n++] = var;
+ while (*e && *e != '\t')
+ b[n++] = *e++;
+ if (*e == '\t')
+ e++;
+ b[n++] = value;
+ while (*e)
+ b[n++] = *e++;
+ e++;
+ }
+ {
+ char user[sizeof(telnet->cfg.username)];
+ (void) get_remote_username(&telnet->cfg, user, sizeof(user));
+ if (*user) {
+ b[n++] = var;
+ b[n++] = 'U';
+ b[n++] = 'S';
+ b[n++] = 'E';
+ b[n++] = 'R';
+ b[n++] = value;
+ e = user;
+ while (*e)
+ b[n++] = *e++;
+ }
+ b[n++] = IAC;
+ b[n++] = SE;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, n);
+ logbuf = dupprintf("client:\tSB %s IS %s%s%s%s",
+ telopt(telnet->sb_opt),
+ *user ? "USER=" : "",
+ user,
+ *user ? " " : "",
+ n == 6 ? "<nothing>" :
+ (*telnet->cfg.environmt ? "<stuff>" : ""));
+ logevent(telnet->frontend, logbuf);
+ sfree(logbuf);
+ }
+ }
+ break;
+ }
+}
+
+static void do_telnet_read(Telnet telnet, char *buf, int len)
+{
+ char *outbuf = NULL;
+ int outbuflen = 0, outbufsize = 0;
+
+#define ADDTOBUF(c) do { \
+ if (outbuflen >= outbufsize) { \
+ outbufsize = outbuflen + 256; \
+ outbuf = sresize(outbuf, outbufsize, char); \
+ } \
+ outbuf[outbuflen++] = (c); \
+} while (0)
+
+ while (len--) {
+ int c = (unsigned char) *buf++;
+
+ switch (telnet->state) {
+ case TOP_LEVEL:
+ case SEENCR:
+ if (c == NUL && telnet->state == SEENCR)
+ telnet->state = TOP_LEVEL;
+ else if (c == IAC)
+ telnet->state = SEENIAC;
+ else {
+ if (!telnet->in_synch)
+ ADDTOBUF(c);
+
+#if 1
+ /* I can't get the F***ing winsock to insert the urgent IAC
+ * into the right position! Even with SO_OOBINLINE it gives
+ * it to recv too soon. And of course the DM byte (that
+ * arrives in the same packet!) appears several K later!!
+ *
+ * Oh well, we do get the DM in the right place so I'll
+ * just stop hiding on the next 0xf2 and hope for the best.
+ */
+ else if (c == DM)
+ telnet->in_synch = 0;
+#endif
+ if (c == CR && telnet->opt_states[o_they_bin.index] != ACTIVE)
+ telnet->state = SEENCR;
+ else
+ telnet->state = TOP_LEVEL;
+ }
+ break;
+ case SEENIAC:
+ if (c == DO)
+ telnet->state = SEENDO;
+ else if (c == DONT)
+ telnet->state = SEENDONT;
+ else if (c == WILL)
+ telnet->state = SEENWILL;
+ else if (c == WONT)
+ telnet->state = SEENWONT;
+ else if (c == SB)
+ telnet->state = SEENSB;
+ else if (c == DM) {
+ telnet->in_synch = 0;
+ telnet->state = TOP_LEVEL;
+ } else {
+ /* ignore everything else; print it if it's IAC */
+ if (c == IAC) {
+ ADDTOBUF(c);
+ }
+ telnet->state = TOP_LEVEL;
+ }
+ break;
+ case SEENWILL:
+ proc_rec_opt(telnet, WILL, c);
+ telnet->state = TOP_LEVEL;
+ break;
+ case SEENWONT:
+ proc_rec_opt(telnet, WONT, c);
+ telnet->state = TOP_LEVEL;
+ break;
+ case SEENDO:
+ proc_rec_opt(telnet, DO, c);
+ telnet->state = TOP_LEVEL;
+ break;
+ case SEENDONT:
+ proc_rec_opt(telnet, DONT, c);
+ telnet->state = TOP_LEVEL;
+ break;
+ case SEENSB:
+ telnet->sb_opt = c;
+ telnet->sb_len = 0;
+ telnet->state = SUBNEGOT;
+ break;
+ case SUBNEGOT:
+ if (c == IAC)
+ telnet->state = SUBNEG_IAC;
+ else {
+ subneg_addchar:
+ if (telnet->sb_len >= telnet->sb_size) {
+ telnet->sb_size += SB_DELTA;
+ telnet->sb_buf = sresize(telnet->sb_buf, telnet->sb_size,
+ unsigned char);
+ }
+ telnet->sb_buf[telnet->sb_len++] = c;
+ telnet->state = SUBNEGOT; /* in case we came here by goto */
+ }
+ break;
+ case SUBNEG_IAC:
+ if (c != SE)
+ goto subneg_addchar; /* yes, it's a hack, I know, but... */
+ else {
+ process_subneg(telnet);
+ telnet->state = TOP_LEVEL;
+ }
+ break;
+ }
+ }
+
+ if (outbuflen)
+ c_write(telnet, outbuf, outbuflen);
+ sfree(outbuf);
+}
+
+static void telnet_log(Plug plug, int type, SockAddr addr, int port,
+ const char *error_msg, int error_code)
+{
+ Telnet telnet = (Telnet) plug;
+ char addrbuf[256], *msg;
+
+ sk_getaddr(addr, addrbuf, lenof(addrbuf));
+
+ if (type == 0)
+ msg = dupprintf("Connecting to %s port %d", addrbuf, port);
+ else
+ msg = dupprintf("Failed to connect to %s: %s", addrbuf, error_msg);
+
+ logevent(telnet->frontend, msg);
+}
+
+static int telnet_closing(Plug plug, const char *error_msg, int error_code,
+ int calling_back)
+{
+ Telnet telnet = (Telnet) plug;
+
+ if (telnet->s) {
+ sk_close(telnet->s);
+ telnet->s = NULL;
+ notify_remote_exit(telnet->frontend);
+ }
+ if (error_msg) {
+ logevent(telnet->frontend, error_msg);
+ connection_fatal(telnet->frontend, "%s", error_msg);
+ }
+ /* Otherwise, the remote side closed the connection normally. */
+ return 0;
+}
+
+static int telnet_receive(Plug plug, int urgent, char *data, int len)
+{
+ Telnet telnet = (Telnet) plug;
+ if (urgent)
+ telnet->in_synch = TRUE;
+ do_telnet_read(telnet, data, len);
+ return 1;
+}
+
+static void telnet_sent(Plug plug, int bufsize)
+{
+ Telnet telnet = (Telnet) plug;
+ telnet->bufsize = bufsize;
+}
+
+/*
+ * Called to set up the Telnet connection.
+ *
+ * Returns an error message, or NULL on success.
+ *
+ * Also places the canonical host name into `realhost'. It must be
+ * freed by the caller.
+ */
+static const char *telnet_init(void *frontend_handle, void **backend_handle,
+ Config *cfg,
+ char *host, int port, char **realhost,
+ int nodelay, int keepalive)
+{
+ static const struct plug_function_table fn_table = {
+ telnet_log,
+ telnet_closing,
+ telnet_receive,
+ telnet_sent
+ };
+ SockAddr addr;
+ const char *err;
+ Telnet telnet;
+
+ telnet = snew(struct telnet_tag);
+ telnet->fn = &fn_table;
+ telnet->cfg = *cfg; /* STRUCTURE COPY */
+ telnet->s = NULL;
+ telnet->echoing = TRUE;
+ telnet->editing = TRUE;
+ telnet->activated = FALSE;
+ telnet->sb_buf = NULL;
+ telnet->sb_size = 0;
+ telnet->frontend = frontend_handle;
+ telnet->term_width = telnet->cfg.width;
+ telnet->term_height = telnet->cfg.height;
+ telnet->state = TOP_LEVEL;
+ telnet->ldisc = NULL;
+ telnet->pinger = NULL;
+ *backend_handle = telnet;
+
+ /*
+ * Try to find host.
+ */
+ {
+ char *buf;
+ buf = dupprintf("Looking up host \"%s\"%s", host,
+ (cfg->addressfamily == ADDRTYPE_IPV4 ? " (IPv4)" :
+ (cfg->addressfamily == ADDRTYPE_IPV6 ? " (IPv6)" :
+ "")));
+ logevent(telnet->frontend, buf);
+ sfree(buf);
+ }
+ addr = name_lookup(host, port, realhost, &telnet->cfg, cfg->addressfamily);
+ if ((err = sk_addr_error(addr)) != NULL) {
+ sk_addr_free(addr);
+ return err;
+ }
+
+ if (port < 0)
+ port = 23; /* default telnet port */
+
+ /*
+ * Open socket.
+ */
+ telnet->s = new_connection(addr, *realhost, port, 0, 1,
+ nodelay, keepalive, (Plug) telnet, &telnet->cfg);
+ if ((err = sk_socket_error(telnet->s)) != NULL)
+ return err;
+
+ telnet->pinger = pinger_new(&telnet->cfg, &telnet_backend, telnet);
+
+ /*
+ * Initialise option states.
+ */
+ if (telnet->cfg.passive_telnet) {
+ const struct Opt *const *o;
+
+ for (o = opts; *o; o++)
+ telnet->opt_states[(*o)->index] = INACTIVE;
+ } else {
+ const struct Opt *const *o;
+
+ for (o = opts; *o; o++) {
+ telnet->opt_states[(*o)->index] = (*o)->initial_state;
+ if (telnet->opt_states[(*o)->index] == REQUESTED)
+ send_opt(telnet, (*o)->send, (*o)->option);
+ }
+ telnet->activated = TRUE;
+ }
+
+ /*
+ * Set up SYNCH state.
+ */
+ telnet->in_synch = FALSE;
+
+ /*
+ * We can send special commands from the start.
+ */
+ update_specials_menu(telnet->frontend);
+
+ /*
+ * loghost overrides realhost, if specified.
+ */
+ if (*telnet->cfg.loghost) {
+ char *colon;
+
+ sfree(*realhost);
+ *realhost = dupstr(telnet->cfg.loghost);
+ colon = strrchr(*realhost, ':');
+ if (colon) {
+ /*
+ * FIXME: if we ever update this aspect of ssh.c for
+ * IPv6 literal management, this should change in line
+ * with it.
+ */
+ *colon++ = '\0';
+ }
+ }
+
+ return NULL;
+}
+
+static void telnet_free(void *handle)
+{
+ Telnet telnet = (Telnet) handle;
+
+ sfree(telnet->sb_buf);
+ if (telnet->s)
+ sk_close(telnet->s);
+ if (telnet->pinger)
+ pinger_free(telnet->pinger);
+ sfree(telnet);
+}
+/*
+ * Reconfigure the Telnet backend. There's no immediate action
+ * necessary, in this backend: we just save the fresh config for
+ * any subsequent negotiations.
+ */
+static void telnet_reconfig(void *handle, Config *cfg)
+{
+ Telnet telnet = (Telnet) handle;
+ pinger_reconfig(telnet->pinger, &telnet->cfg, cfg);
+ telnet->cfg = *cfg; /* STRUCTURE COPY */
+}
+
+/*
+ * Called to send data down the Telnet connection.
+ */
+static int telnet_send(void *handle, char *buf, int len)
+{
+ Telnet telnet = (Telnet) handle;
+ unsigned char *p, *end;
+ static const unsigned char iac[2] = { IAC, IAC };
+ static const unsigned char cr[2] = { CR, NUL };
+#if 0
+ static const unsigned char nl[2] = { CR, LF };
+#endif
+
+ if (telnet->s == NULL)
+ return 0;
+
+ p = (unsigned char *)buf;
+ end = (unsigned char *)(buf + len);
+ while (p < end) {
+ unsigned char *q = p;
+
+ while (p < end && iswritable(*p))
+ p++;
+ telnet->bufsize = sk_write(telnet->s, (char *)q, p - q);
+
+ while (p < end && !iswritable(*p)) {
+ telnet->bufsize =
+ sk_write(telnet->s, (char *)(*p == IAC ? iac : cr), 2);
+ p++;
+ }
+ }
+
+ return telnet->bufsize;
+}
+
+/*
+ * Called to query the current socket sendability status.
+ */
+static int telnet_sendbuffer(void *handle)
+{
+ Telnet telnet = (Telnet) handle;
+ return telnet->bufsize;
+}
+
+/*
+ * Called to set the size of the window from Telnet's POV.
+ */
+static void telnet_size(void *handle, int width, int height)
+{
+ Telnet telnet = (Telnet) handle;
+ unsigned char b[24];
+ int n;
+ char *logbuf;
+
+ telnet->term_width = width;
+ telnet->term_height = height;
+
+ if (telnet->s == NULL || telnet->opt_states[o_naws.index] != ACTIVE)
+ return;
+ n = 0;
+ b[n++] = IAC;
+ b[n++] = SB;
+ b[n++] = TELOPT_NAWS;
+ b[n++] = telnet->term_width >> 8;
+ if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
+ b[n++] = telnet->term_width & 0xFF;
+ if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
+ b[n++] = telnet->term_height >> 8;
+ if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
+ b[n++] = telnet->term_height & 0xFF;
+ if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
+ b[n++] = IAC;
+ b[n++] = SE;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, n);
+ logbuf = dupprintf("client:\tSB NAWS %d,%d",
+ telnet->term_width, telnet->term_height);
+ logevent(telnet->frontend, logbuf);
+ sfree(logbuf);
+}
+
+/*
+ * Send Telnet special codes.
+ */
+static void telnet_special(void *handle, Telnet_Special code)
+{
+ Telnet telnet = (Telnet) handle;
+ unsigned char b[2];
+
+ if (telnet->s == NULL)
+ return;
+
+ b[0] = IAC;
+ switch (code) {
+ case TS_AYT:
+ b[1] = AYT;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ break;
+ case TS_BRK:
+ b[1] = BREAK;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ break;
+ case TS_EC:
+ b[1] = EC;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ break;
+ case TS_EL:
+ b[1] = EL;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ break;
+ case TS_GA:
+ b[1] = GA;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ break;
+ case TS_NOP:
+ b[1] = NOP;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ break;
+ case TS_ABORT:
+ b[1] = ABORT;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ break;
+ case TS_AO:
+ b[1] = AO;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ break;
+ case TS_IP:
+ b[1] = IP;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ break;
+ case TS_SUSP:
+ b[1] = SUSP;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ break;
+ case TS_EOR:
+ b[1] = EOR;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ break;
+ case TS_EOF:
+ b[1] = xEOF;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ break;
+ case TS_EOL:
+ /* In BINARY mode, CR-LF becomes just CR -
+ * and without the NUL suffix too. */
+ if (telnet->opt_states[o_we_bin.index] == ACTIVE)
+ telnet->bufsize = sk_write(telnet->s, "\r", 1);
+ else
+ telnet->bufsize = sk_write(telnet->s, "\r\n", 2);
+ break;
+ case TS_SYNCH:
+ b[1] = DM;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 1);
+ telnet->bufsize = sk_write_oob(telnet->s, (char *)(b + 1), 1);
+ break;
+ case TS_RECHO:
+ if (telnet->opt_states[o_echo.index] == INACTIVE ||
+ telnet->opt_states[o_echo.index] == REALLY_INACTIVE) {
+ telnet->opt_states[o_echo.index] = REQUESTED;
+ send_opt(telnet, o_echo.send, o_echo.option);
+ }
+ break;
+ case TS_LECHO:
+ if (telnet->opt_states[o_echo.index] == ACTIVE) {
+ telnet->opt_states[o_echo.index] = REQUESTED;
+ send_opt(telnet, o_echo.nsend, o_echo.option);
+ }
+ break;
+ case TS_PING:
+ if (telnet->opt_states[o_they_sga.index] == ACTIVE) {
+ b[1] = NOP;
+ telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
+ }
+ break;
+ default:
+ break; /* never heard of it */
+ }
+}
+
+static const struct telnet_special *telnet_get_specials(void *handle)
+{
+ static const struct telnet_special specials[] = {
+ {"Are You There", TS_AYT},
+ {"Break", TS_BRK},
+ {"Synch", TS_SYNCH},
+ {"Erase Character", TS_EC},
+ {"Erase Line", TS_EL},
+ {"Go Ahead", TS_GA},
+ {"No Operation", TS_NOP},
+ {NULL, TS_SEP},
+ {"Abort Process", TS_ABORT},
+ {"Abort Output", TS_AO},
+ {"Interrupt Process", TS_IP},
+ {"Suspend Process", TS_SUSP},
+ {NULL, TS_SEP},
+ {"End Of Record", TS_EOR},
+ {"End Of File", TS_EOF},
+ {NULL, TS_EXITMENU}
+ };
+ return specials;
+}
+
+static int telnet_connected(void *handle)
+{
+ Telnet telnet = (Telnet) handle;
+ return telnet->s != NULL;
+}
+
+static int telnet_sendok(void *handle)
+{
+ /* Telnet telnet = (Telnet) handle; */
+ return 1;
+}
+
+static void telnet_unthrottle(void *handle, int backlog)
+{
+ Telnet telnet = (Telnet) handle;
+ sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
+}
+
+static int telnet_ldisc(void *handle, int option)
+{
+ Telnet telnet = (Telnet) handle;
+ if (option == LD_ECHO)
+ return telnet->echoing;
+ if (option == LD_EDIT)
+ return telnet->editing;
+ return FALSE;
+}
+
+static void telnet_provide_ldisc(void *handle, void *ldisc)
+{
+ Telnet telnet = (Telnet) handle;
+ telnet->ldisc = ldisc;
+}
+
+static void telnet_provide_logctx(void *handle, void *logctx)
+{
+ /* This is a stub. */
+}
+
+static int telnet_exitcode(void *handle)
+{
+ Telnet telnet = (Telnet) handle;
+ if (telnet->s != NULL)
+ return -1; /* still connected */
+ else
+ /* Telnet doesn't transmit exit codes back to the client */
+ return 0;
+}
+
+/*
+ * cfg_info for Telnet does nothing at all.
+ */
+static int telnet_cfg_info(void *handle)
+{
+ return 0;
+}
+
+Backend telnet_backend = {
+ telnet_init,
+ telnet_free,
+ telnet_reconfig,
+ telnet_send,
+ telnet_sendbuffer,
+ telnet_size,
+ telnet_special,
+ telnet_get_specials,
+ telnet_connected,
+ telnet_exitcode,
+ telnet_sendok,
+ telnet_ldisc,
+ telnet_provide_ldisc,
+ telnet_provide_logctx,
+ telnet_unthrottle,
+ telnet_cfg_info,
+ "telnet",
+ PROT_TELNET,
+ 23
+};
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