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telnet.c
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telnet.c
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/*
* 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 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;
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++;
}
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%s%s%s",
telopt(telnet->sb_opt),
*telnet->cfg.username ? "USER=" : "",
telnet->cfg.username,
*telnet->cfg.username ? " " : "",
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);
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;