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;
65 * We have no way to communicate down the forwarded connection,
66 * so if an error occurred on the socket, we just ignore it
67 * and treat it like a proper close.
75 static int pfd_receive(Plug plug, int urgent, char *data, int len)
77 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
81 * Throughout SOCKS negotiation, "hostname" is re-used as a
82 * random protocol buffer with "port" storing the length.
84 if (pr->port >= lenof(pr->hostname)) {
85 /* Request too long. */
86 if ((pr->dynamic >> 12) == 4) {
87 /* Send back a SOCKS 4 error before closing. */
89 memset(data, 0, sizeof(data));
90 data[1] = 91; /* generic `request rejected' */
91 sk_write(pr->s, data, 8);
96 pr->hostname[pr->port++] = *data++;
99 * Now check what's in the buffer to see if it's a
100 * valid and complete message in the SOCKS exchange.
102 if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) &&
103 pr->hostname[0] == 4) {
107 if (pr->dynamic == 1)
108 pr->dynamic = 0x4000;
109 if (pr->port < 2) continue;/* don't have command code yet */
110 if (pr->hostname[1] != 1) {
112 /* Send back a SOCKS 4 error before closing. */
114 memset(data, 0, sizeof(data));
115 data[1] = 91; /* generic `request rejected' */
116 sk_write(pr->s, data, 8);
120 if (pr->port <= 8) continue; /* haven't started user/hostname */
121 if (pr->hostname[pr->port-1] != 0)
122 continue; /* haven't _finished_ user/hostname */
124 * Now we have a full SOCKS 4 request. Check it to
125 * see if it's a SOCKS 4A request.
127 if (pr->hostname[4] == 0 && pr->hostname[5] == 0 &&
128 pr->hostname[6] == 0 && pr->hostname[7] != 0) {
130 * It's SOCKS 4A. So if we haven't yet
131 * collected the host name, we should continue
132 * waiting for data in order to do so; if we
133 * have, we can go ahead.
136 if (pr->dynamic == 0x4000) {
137 pr->dynamic = 0x4001;
138 pr->port = 8; /* reset buffer to overwrite name */
141 pr->hostname[0] = 0; /* reply version code */
142 pr->hostname[1] = 90; /* request granted */
143 sk_write(pr->s, pr->hostname, 8);
145 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
146 memmove(pr->hostname, pr->hostname + 8, len);
150 * It's SOCKS 4, which means we should format
151 * the IP address into the hostname string and
154 pr->hostname[0] = 0; /* reply version code */
155 pr->hostname[1] = 90; /* request granted */
156 sk_write(pr->s, pr->hostname, 8);
157 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
158 sprintf(pr->hostname, "%d.%d.%d.%d",
159 (unsigned char)pr->hostname[4],
160 (unsigned char)pr->hostname[5],
161 (unsigned char)pr->hostname[6],
162 (unsigned char)pr->hostname[7]);
167 if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) &&
168 pr->hostname[0] == 5) {
172 if (pr->dynamic == 1)
173 pr->dynamic = 0x5000;
175 if (pr->dynamic == 0x5000) {
179 * We're receiving a set of method identifiers.
181 if (pr->port < 2) continue;/* no method count yet */
182 if (pr->port < 2 + (unsigned char)pr->hostname[1])
183 continue; /* no methods yet */
184 method = 0xFF; /* invalid */
185 for (i = 0; i < (unsigned char)pr->hostname[1]; i++)
186 if (pr->hostname[2+i] == 0) {
187 method = 0;/* no auth */
192 sk_write(pr->s, data, 2);
193 pr->dynamic = 0x5001;
194 pr->port = 0; /* re-empty the buffer */
198 if (pr->dynamic == 0x5001) {
200 * We're receiving a SOCKS request.
202 unsigned char reply[10]; /* SOCKS5 atyp=1 reply */
206 * Pre-fill reply packet.
207 * In all cases, we set BND.{HOST,ADDR} to 0.0.0.0:0
208 * (atyp=1) in the reply; if we succeed, we don't know
209 * the right answers, and if we fail, they should be
212 memset(reply, 0, lenof(reply));
213 reply[0] = 5; /* VER */
214 reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */
216 if (pr->port < 6) continue;
217 atype = (unsigned char)pr->hostname[3];
218 if (atype == 1) /* IPv4 address */
220 if (atype == 4) /* IPv6 address */
222 if (atype == 3) /* domain name has leading length */
223 alen = 1 + (unsigned char)pr->hostname[4];
224 if (pr->port < 6 + alen) continue;
225 if (pr->hostname[1] != 1 || pr->hostname[2] != 0) {
226 /* Not CONNECT or reserved field nonzero - error */
227 reply[1] = 1; /* generic failure */
228 sk_write(pr->s, (char *) reply, lenof(reply));
233 * Now we have a viable connect request. Switch
236 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen);
238 /* REP=0 (success) already */
239 sk_write(pr->s, (char *) reply, lenof(reply));
240 sprintf(pr->hostname, "%d.%d.%d.%d",
241 (unsigned char)pr->hostname[4],
242 (unsigned char)pr->hostname[5],
243 (unsigned char)pr->hostname[6],
244 (unsigned char)pr->hostname[7]);
246 } else if (atype == 3) {
247 /* REP=0 (success) already */
248 sk_write(pr->s, (char *) reply, lenof(reply));
249 memmove(pr->hostname, pr->hostname + 5, alen-1);
250 pr->hostname[alen-1] = '\0';
254 * Unknown address type. (FIXME: support IPv6!)
256 reply[1] = 8; /* atype not supported */
257 sk_write(pr->s, (char *) reply, lenof(reply));
265 * If we get here without either having done `continue'
266 * or `goto connect', it must be because there is no
267 * sensible interpretation of what's in our buffer. So
268 * close the connection rudely.
276 * We come here when we're ready to make an actual
281 pr->c = new_sock_channel(pr->backhandle, pr->s);
286 /* asks to forward to the specified host/port for this */
287 ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
292 * Now freeze the socket until the SSH server confirms the
295 sk_set_frozen(pr->s, 1);
297 * If there's any data remaining in our current buffer,
298 * save it to be sent on pfd_confirm().
301 pr->buffer = snewn(len, char);
302 memcpy(pr->buffer, data, len);
307 if (sshfwd_write(pr->c, data, len) > 0) {
309 sk_set_frozen(pr->s, 1);
315 static void pfd_sent(Plug plug, int bufsize)
317 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
320 sshfwd_unthrottle(pr->c, bufsize);
324 * Called when receiving a PORT OPEN from the server
326 const char *pfd_newconnect(Socket *s, char *hostname, int port,
327 void *c, const Config *cfg, int addressfamily)
329 static const struct plug_function_table fn_table = {
339 char *dummy_realhost;
340 struct PFwdPrivate *pr;
345 addr = name_lookup(hostname, port, &dummy_realhost, cfg, addressfamily);
346 if ((err = sk_addr_error(addr)) != NULL) {
354 pr = snew(struct PFwdPrivate);
357 pr->throttled = pr->throttle_override = 0;
360 pr->backhandle = NULL; /* we shouldn't need this */
363 pr->s = *s = new_connection(addr, dummy_realhost, port,
364 0, 1, 0, 0, (Plug) pr, cfg);
365 if ((err = sk_socket_error(*s)) != NULL) {
370 sk_set_private_ptr(*s, pr);
375 called when someone connects to the local port
378 static int pfd_accepting(Plug p, OSSocket sock)
380 static const struct plug_function_table fn_table = {
387 struct PFwdPrivate *pr, *org;
391 org = (struct PFwdPrivate *)p;
392 pr = snew(struct PFwdPrivate);
397 pr->backhandle = org->backhandle;
399 pr->s = s = sk_register(sock, (Plug) pr);
400 if ((err = sk_socket_error(s)) != NULL) {
405 sk_set_private_ptr(s, pr);
407 pr->throttled = pr->throttle_override = 0;
412 pr->port = 0; /* "hostname" buffer is so far empty */
413 sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */
416 strcpy(pr->hostname, org->hostname);
417 pr->port = org->port;
418 pr->c = new_sock_channel(org->backhandle, s);
424 /* asks to forward to the specified host/port for this */
425 ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
433 /* Add a new forwarding from port -> desthost:destport
434 sets up a listener on the local machine on (srcaddr:)port
436 const char *pfd_addforward(char *desthost, int destport, char *srcaddr,
437 int port, void *backhandle, const Config *cfg,
438 void **sockdata, int address_family)
440 static const struct plug_function_table fn_table = {
443 pfd_receive, /* should not happen... */
444 pfd_sent, /* also should not happen */
449 struct PFwdPrivate *pr;
455 pr = snew(struct PFwdPrivate);
460 strcpy(pr->hostname, desthost);
465 pr->throttled = pr->throttle_override = 0;
467 pr->backhandle = backhandle;
469 pr->s = s = new_listener(srcaddr, port, (Plug) pr,
470 !cfg->lport_acceptall, cfg, address_family);
471 if ((err = sk_socket_error(s)) != NULL) {
476 sk_set_private_ptr(s, pr);
478 *sockdata = (void *)s;
483 void pfd_close(Socket s)
485 struct PFwdPrivate *pr;
490 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
499 * Terminate a listener.
501 void pfd_terminate(void *sv)
503 pfd_close((Socket)sv);
506 void pfd_unthrottle(Socket s)
508 struct PFwdPrivate *pr;
511 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
514 sk_set_frozen(s, pr->throttled || pr->throttle_override);
517 void pfd_override_throttle(Socket s, int enable)
519 struct PFwdPrivate *pr;
522 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
524 pr->throttle_override = enable;
525 sk_set_frozen(s, pr->throttled || pr->throttle_override);
529 * Called to send data down the raw connection.
531 int pfd_send(Socket s, char *data, int len)
535 return sk_write(s, data, len);
539 void pfd_confirm(Socket s)
541 struct PFwdPrivate *pr;
546 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
549 sk_write(s, NULL, 0);
551 sshfwd_write(pr->c, pr->buffer, pr->buflen);