19 const struct plug_function_table *fn;
20 /* the above variable absolutely *must* be the first in this structure */
21 void *c; /* (channel) data used by ssh.c */
22 void *backhandle; /* instance of SSH backend itself */
23 /* Note that backhandle need not be filled in if c is non-NULL */
25 int throttled, throttle_override;
28 * `dynamic' does double duty. It's set to 0 for an ordinary
29 * forwarded port, and nonzero for SOCKS-style dynamic port
30 * forwarding; but it also represents the state of the SOCKS
35 * `hostname' and `port' are the real hostname and port, once
36 * we know what we're connecting to; they're unused for this
37 * purpose while conducting a local SOCKS exchange, which means
38 * we can also use them as a buffer and pointer for reading
39 * data from the SOCKS client.
44 * When doing dynamic port forwarding, we can receive
45 * connection data before we are actually able to send it; so
46 * we may have to temporarily hold some in a dynamically
47 * allocated buffer here.
53 static void pfd_log(Plug plug, int type, SockAddr addr, int port,
54 const char *error_msg, int error_code)
56 /* we have to dump these since we have no interface to logging.c */
59 static int pfd_closing(Plug plug, const char *error_msg, int error_code,
62 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
66 * Socket error. Slam the connection instantly shut.
68 sshfwd_unclean_close(pr->c);
71 * Ordinary EOF received on socket. Send an EOF on the SSH
75 sshfwd_write_eof(pr->c);
81 static int pfd_receive(Plug plug, int urgent, char *data, int len)
83 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
87 * Throughout SOCKS negotiation, "hostname" is re-used as a
88 * random protocol buffer with "port" storing the length.
90 if (pr->port >= lenof(pr->hostname)) {
91 /* Request too long. */
92 if ((pr->dynamic >> 12) == 4) {
93 /* Send back a SOCKS 4 error before closing. */
95 memset(data, 0, sizeof(data));
96 data[1] = 91; /* generic `request rejected' */
97 sk_write(pr->s, data, 8);
102 pr->hostname[pr->port++] = *data++;
105 * Now check what's in the buffer to see if it's a
106 * valid and complete message in the SOCKS exchange.
108 if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) &&
109 pr->hostname[0] == 4) {
113 if (pr->dynamic == 1)
114 pr->dynamic = 0x4000;
115 if (pr->port < 2) continue;/* don't have command code yet */
116 if (pr->hostname[1] != 1) {
118 /* Send back a SOCKS 4 error before closing. */
120 memset(data, 0, sizeof(data));
121 data[1] = 91; /* generic `request rejected' */
122 sk_write(pr->s, data, 8);
126 if (pr->port <= 8) continue; /* haven't started user/hostname */
127 if (pr->hostname[pr->port-1] != 0)
128 continue; /* haven't _finished_ user/hostname */
130 * Now we have a full SOCKS 4 request. Check it to
131 * see if it's a SOCKS 4A request.
133 if (pr->hostname[4] == 0 && pr->hostname[5] == 0 &&
134 pr->hostname[6] == 0 && pr->hostname[7] != 0) {
136 * It's SOCKS 4A. So if we haven't yet
137 * collected the host name, we should continue
138 * waiting for data in order to do so; if we
139 * have, we can go ahead.
142 if (pr->dynamic == 0x4000) {
143 pr->dynamic = 0x4001;
144 pr->port = 8; /* reset buffer to overwrite name */
147 pr->hostname[0] = 0; /* reply version code */
148 pr->hostname[1] = 90; /* request granted */
149 sk_write(pr->s, pr->hostname, 8);
151 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
152 memmove(pr->hostname, pr->hostname + 8, len);
156 * It's SOCKS 4, which means we should format
157 * the IP address into the hostname string and
160 pr->hostname[0] = 0; /* reply version code */
161 pr->hostname[1] = 90; /* request granted */
162 sk_write(pr->s, pr->hostname, 8);
163 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
164 sprintf(pr->hostname, "%d.%d.%d.%d",
165 (unsigned char)pr->hostname[4],
166 (unsigned char)pr->hostname[5],
167 (unsigned char)pr->hostname[6],
168 (unsigned char)pr->hostname[7]);
173 if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) &&
174 pr->hostname[0] == 5) {
178 if (pr->dynamic == 1)
179 pr->dynamic = 0x5000;
181 if (pr->dynamic == 0x5000) {
185 * We're receiving a set of method identifiers.
187 if (pr->port < 2) continue;/* no method count yet */
188 if (pr->port < 2 + (unsigned char)pr->hostname[1])
189 continue; /* no methods yet */
190 method = 0xFF; /* invalid */
191 for (i = 0; i < (unsigned char)pr->hostname[1]; i++)
192 if (pr->hostname[2+i] == 0) {
193 method = 0;/* no auth */
198 sk_write(pr->s, data, 2);
199 pr->dynamic = 0x5001;
200 pr->port = 0; /* re-empty the buffer */
204 if (pr->dynamic == 0x5001) {
206 * We're receiving a SOCKS request.
208 unsigned char reply[10]; /* SOCKS5 atyp=1 reply */
212 * Pre-fill reply packet.
213 * In all cases, we set BND.{HOST,ADDR} to 0.0.0.0:0
214 * (atyp=1) in the reply; if we succeed, we don't know
215 * the right answers, and if we fail, they should be
218 memset(reply, 0, lenof(reply));
219 reply[0] = 5; /* VER */
220 reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */
222 if (pr->port < 6) continue;
223 atype = (unsigned char)pr->hostname[3];
224 if (atype == 1) /* IPv4 address */
226 if (atype == 4) /* IPv6 address */
228 if (atype == 3) /* domain name has leading length */
229 alen = 1 + (unsigned char)pr->hostname[4];
230 if (pr->port < 6 + alen) continue;
231 if (pr->hostname[1] != 1 || pr->hostname[2] != 0) {
232 /* Not CONNECT or reserved field nonzero - error */
233 reply[1] = 1; /* generic failure */
234 sk_write(pr->s, (char *) reply, lenof(reply));
239 * Now we have a viable connect request. Switch
242 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen);
244 /* REP=0 (success) already */
245 sk_write(pr->s, (char *) reply, lenof(reply));
246 sprintf(pr->hostname, "%d.%d.%d.%d",
247 (unsigned char)pr->hostname[4],
248 (unsigned char)pr->hostname[5],
249 (unsigned char)pr->hostname[6],
250 (unsigned char)pr->hostname[7]);
252 } else if (atype == 3) {
253 /* REP=0 (success) already */
254 sk_write(pr->s, (char *) reply, lenof(reply));
255 memmove(pr->hostname, pr->hostname + 5, alen-1);
256 pr->hostname[alen-1] = '\0';
260 * Unknown address type. (FIXME: support IPv6!)
262 reply[1] = 8; /* atype not supported */
263 sk_write(pr->s, (char *) reply, lenof(reply));
271 * If we get here without either having done `continue'
272 * or `goto connect', it must be because there is no
273 * sensible interpretation of what's in our buffer. So
274 * close the connection rudely.
282 * We come here when we're ready to make an actual
288 * Freeze the socket until the SSH server confirms the
291 sk_set_frozen(pr->s, 1);
293 pr->c = new_sock_channel(pr->backhandle, pr->s);
298 /* asks to forward to the specified host/port for this */
299 ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
304 * If there's any data remaining in our current buffer,
305 * save it to be sent on pfd_confirm().
308 pr->buffer = snewn(len, char);
309 memcpy(pr->buffer, data, len);
314 if (sshfwd_write(pr->c, data, len) > 0) {
316 sk_set_frozen(pr->s, 1);
322 static void pfd_sent(Plug plug, int bufsize)
324 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
327 sshfwd_unthrottle(pr->c, bufsize);
331 * Called when receiving a PORT OPEN from the server
333 const char *pfd_newconnect(Socket *s, char *hostname, int port,
334 void *c, Conf *conf, int addressfamily)
336 static const struct plug_function_table fn_table = {
346 char *dummy_realhost;
347 struct PFwdPrivate *pr;
352 addr = name_lookup(hostname, port, &dummy_realhost, conf, addressfamily);
353 if ((err = sk_addr_error(addr)) != NULL) {
361 pr = snew(struct PFwdPrivate);
364 pr->throttled = pr->throttle_override = 0;
367 pr->backhandle = NULL; /* we shouldn't need this */
370 pr->s = *s = new_connection(addr, dummy_realhost, port,
371 0, 1, 0, 0, (Plug) pr, conf);
372 if ((err = sk_socket_error(*s)) != NULL) {
377 sk_set_private_ptr(*s, pr);
382 called when someone connects to the local port
385 static int pfd_accepting(Plug p, OSSocket sock)
387 static const struct plug_function_table fn_table = {
394 struct PFwdPrivate *pr, *org;
398 org = (struct PFwdPrivate *)p;
399 pr = snew(struct PFwdPrivate);
404 pr->backhandle = org->backhandle;
406 pr->s = s = sk_register(sock, (Plug) pr);
407 if ((err = sk_socket_error(s)) != NULL) {
412 sk_set_private_ptr(s, pr);
414 pr->throttled = pr->throttle_override = 0;
419 pr->port = 0; /* "hostname" buffer is so far empty */
420 sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */
423 strcpy(pr->hostname, org->hostname);
424 pr->port = org->port;
425 pr->c = new_sock_channel(org->backhandle, s);
431 /* asks to forward to the specified host/port for this */
432 ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
440 /* Add a new forwarding from port -> desthost:destport
441 sets up a listener on the local machine on (srcaddr:)port
443 const char *pfd_addforward(char *desthost, int destport, char *srcaddr,
444 int port, void *backhandle, Conf *conf,
445 void **sockdata, int address_family)
447 static const struct plug_function_table fn_table = {
450 pfd_receive, /* should not happen... */
451 pfd_sent, /* also should not happen */
456 struct PFwdPrivate *pr;
462 pr = snew(struct PFwdPrivate);
467 strcpy(pr->hostname, desthost);
472 pr->throttled = pr->throttle_override = 0;
474 pr->backhandle = backhandle;
476 pr->s = s = new_listener(srcaddr, port, (Plug) pr,
477 !conf_get_int(conf, CONF_lport_acceptall),
478 conf, address_family);
479 if ((err = sk_socket_error(s)) != NULL) {
484 sk_set_private_ptr(s, pr);
486 *sockdata = (void *)s;
491 void pfd_close(Socket s)
493 struct PFwdPrivate *pr;
498 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
507 * Terminate a listener.
509 void pfd_terminate(void *sv)
511 pfd_close((Socket)sv);
514 void pfd_unthrottle(Socket s)
516 struct PFwdPrivate *pr;
519 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
522 sk_set_frozen(s, pr->throttled || pr->throttle_override);
525 void pfd_override_throttle(Socket s, int enable)
527 struct PFwdPrivate *pr;
530 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
532 pr->throttle_override = enable;
533 sk_set_frozen(s, pr->throttled || pr->throttle_override);
537 * Called to send data down the raw connection.
539 int pfd_send(Socket s, char *data, int len)
543 return sk_write(s, data, len);
546 void pfd_send_eof(Socket s)
551 void pfd_confirm(Socket s)
553 struct PFwdPrivate *pr;
558 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
561 sk_write(s, NULL, 0);
563 sshfwd_write(pr->c, pr->buffer, pr->buflen);