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putty-source/telnet.c
Jacob Nevins 20f433efac Add a configuration option for TCP keepalives (SO_KEEPALIVE), default off. 
No very good reason, but I've occasionally wanted to frob it to see if it
makes any difference to problems I'm having, and it was easy.

Tested that it does actually cause keepalives on Windows (with tcpdump);
should also work on Unix. Not implemented on Mac (does nothing), but then
neither is TCP_NODELAY.

Quite a big checkin, much of which is adding `keepalive' alongside `nodelay'
in network function calls.

[originally from svn r4309]
2004-06-20 17:07:38 +00:00

1049 lines
28 KiB
C
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#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 TELOPT_BINARY 0 /* 8-bit data path */
#define TELOPT_ECHO 1 /* echo */
#define TELOPT_RCP 2 /* prepare to reconnect */
#define TELOPT_SGA 3 /* suppress go ahead */
#define TELOPT_NAMS 4 /* approximate message size */
#define TELOPT_STATUS 5 /* give status */
#define TELOPT_TM 6 /* timing mark */
#define TELOPT_RCTE 7 /* remote controlled transmission and echo */
#define TELOPT_NAOL 8 /* negotiate about output line width */
#define TELOPT_NAOP 9 /* negotiate about output page size */
#define TELOPT_NAOCRD 10 /* negotiate about CR disposition */
#define TELOPT_NAOHTS 11 /* negotiate about horizontal tabstops */
#define TELOPT_NAOHTD 12 /* negotiate about horizontal tab disposition */
#define TELOPT_NAOFFD 13 /* negotiate about formfeed disposition */
#define TELOPT_NAOVTS 14 /* negotiate about vertical tab stops */
#define TELOPT_NAOVTD 15 /* negotiate about vertical tab disposition */
#define TELOPT_NAOLFD 16 /* negotiate about output LF disposition */
#define TELOPT_XASCII 17 /* extended ascic character set */
#define TELOPT_LOGOUT 18 /* force logout */
#define TELOPT_BM 19 /* byte macro */
#define TELOPT_DET 20 /* data entry terminal */
#define TELOPT_SUPDUP 21 /* supdup protocol */
#define TELOPT_SUPDUPOUTPUT 22 /* supdup output */
#define TELOPT_SNDLOC 23 /* send location */
#define TELOPT_TTYPE 24 /* terminal type */
#define TELOPT_EOR 25 /* end or record */
#define TELOPT_TUID 26 /* TACACS user identification */
#define TELOPT_OUTMRK 27 /* output marking */
#define TELOPT_TTYLOC 28 /* terminal location number */
#define TELOPT_3270REGIME 29 /* 3270 regime */
#define TELOPT_X3PAD 30 /* X.3 PAD */
#define TELOPT_NAWS 31 /* window size */
#define TELOPT_TSPEED 32 /* terminal speed */
#define TELOPT_LFLOW 33 /* remote flow control */
#define TELOPT_LINEMODE 34 /* Linemode option */
#define TELOPT_XDISPLOC 35 /* X Display Location */
#define TELOPT_OLD_ENVIRON 36 /* Old - Environment variables */
#define TELOPT_AUTHENTICATION 37 /* Authenticate */
#define TELOPT_ENCRYPT 38 /* Encryption option */
#define TELOPT_NEW_ENVIRON 39 /* New - Environment variables */
#define TELOPT_TN3270E 40 /* TN3270 enhancements */
#define TELOPT_XAUTH 41
#define TELOPT_CHARSET 42 /* Character set */
#define TELOPT_RSP 43 /* Remote serial port */
#define TELOPT_COM_PORT_OPTION 44 /* Com port control */
#define TELOPT_SLE 45 /* Suppress local echo */
#define TELOPT_STARTTLS 46 /* Start TLS */
#define TELOPT_KERMIT 47 /* Automatic Kermit file transfer */
#define TELOPT_SEND_URL 48
#define TELOPT_FORWARD_X 49
#define TELOPT_PRAGMA_LOGON 138
#define TELOPT_SSPI_LOGON 139
#define TELOPT_PRAGMA_HEARTBEAT 140
#define TELOPT_EXOPL 255 /* extended-options-list */
#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 i(x) if (opt == TELOPT_ ## x) return #x;
i(BINARY);
i(ECHO);
i(RCP);
i(SGA);
i(NAMS);
i(STATUS);
i(TM);
i(RCTE);
i(NAOL);
i(NAOP);
i(NAOCRD);
i(NAOHTS);
i(NAOHTD);
i(NAOFFD);
i(NAOVTS);
i(NAOVTD);
i(NAOLFD);
i(XASCII);
i(LOGOUT);
i(BM);
i(DET);
i(SUPDUP);
i(SUPDUPOUTPUT);
i(SNDLOC);
i(TTYPE);
i(EOR);
i(TUID);
i(OUTMRK);
i(TTYLOC);
i(X3PAD);
i(NAWS);
i(TSPEED);
i(LFLOW);
i(LINEMODE);
i(XDISPLOC);
i(OLD_ENVIRON);
i(AUTHENTICATION);
i(ENCRYPT);
i(NEW_ENVIRON);
i(TN3270E);
i(XAUTH);
i(CHARSET);
i(RSP);
i(COM_PORT_OPTION);
i(SLE);
i(STARTTLS);
i(KERMIT);
i(SEND_URL);
i(FORWARD_X);
i(PRAGMA_LOGON);
i(SSPI_LOGON);
i(PRAGMA_HEARTBEAT);
i(EXOPL);
#undef i
return "<unknown>";
}
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;
} *Telnet;
#define TELNET_MAX_BACKLOG 4096
#define SB_DELTA 1024
static void c_write1(Telnet telnet, int c)
{
int backlog;
char cc = (char) c;
backlog = from_backend(telnet->frontend, 0, &cc, 1);
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. So send a negative ack.
*/
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++;
}
if (*telnet->cfg.username) {
b[n++] = var;
b[n++] = 'U';
b[n++] = 'S';
b[n++] = 'E';
b[n++] = 'R';
b[n++] = value;
e = telnet->cfg.username;
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", telopt(telnet->sb_opt),
n == 6 ? "<nothing>" : "<stuff>");
logevent(telnet->frontend, logbuf);
sfree(logbuf);
}
break;
}
}
static void do_telnet_read(Telnet telnet, char *buf, int len)
{
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)
c_write1(telnet, 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) {
c_write1(telnet, 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;
}
}
}
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;
}
if (error_msg) {
/* A socket error has occurred. */
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_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;
*backend_handle = telnet;
/*
* Try to find host.
*/
{
char *buf;
buf = dupprintf("Looking up host \"%s\"", host);
logevent(telnet->frontend, buf);
sfree(buf);
}
addr = name_lookup(host, port, realhost, &telnet->cfg);
if ((err = sk_addr_error(addr)) != NULL) {
sk_addr_free(addr);
return err;
}
if (port < 0)
port = 23; /* default telnet port */
/*
* Open socket.
*/
{
char *buf, addrbuf[100];
sk_getaddr(addr, addrbuf, 100);
buf = dupprintf("Connecting to %s port %d", addrbuf, port);
logevent(telnet->frontend, buf);
sfree(buf);
}
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;
/*
* 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;
return NULL;
}
static void telnet_free(void *handle)
{
Telnet telnet = (Telnet) handle;
sfree(telnet->sb_buf);
if (telnet->s)
sk_close(telnet->s);
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;
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;
}
}
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},
{"", 0},
{"Abort Process", TS_ABORT},
{"Abort Output", TS_AO},
{"Interrupt Process", TS_IP},
{"Suspend Process", TS_SUSP},
{"", 0},
{"End Of Record", TS_EOR},
{"End Of File", TS_EOF},
{NULL, 0}
};
return specials;
}
static Socket telnet_socket(void *handle)
{
Telnet telnet = (Telnet) handle;
return telnet->s;
}
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;
}
Backend telnet_backend = {
telnet_init,
telnet_free,
telnet_reconfig,
telnet_send,
telnet_sendbuffer,
telnet_size,
telnet_special,
telnet_get_specials,
telnet_socket,
telnet_exitcode,
telnet_sendok,
telnet_ldisc,
telnet_provide_ldisc,
telnet_provide_logctx,
telnet_unthrottle,
23
};
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