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.
69 * FIXME: except we could initiate a full close here instead of
70 * just an outgoing EOF? ssh.c currently has no API for that, but
74 sshfwd_write_eof(pr->c);
79 static int pfd_receive(Plug plug, int urgent, char *data, int len)
81 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
85 * Throughout SOCKS negotiation, "hostname" is re-used as a
86 * random protocol buffer with "port" storing the length.
88 if (pr->port >= lenof(pr->hostname)) {
89 /* Request too long. */
90 if ((pr->dynamic >> 12) == 4) {
91 /* Send back a SOCKS 4 error before closing. */
93 memset(data, 0, sizeof(data));
94 data[1] = 91; /* generic `request rejected' */
95 sk_write(pr->s, data, 8);
100 pr->hostname[pr->port++] = *data++;
103 * Now check what's in the buffer to see if it's a
104 * valid and complete message in the SOCKS exchange.
106 if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) &&
107 pr->hostname[0] == 4) {
111 if (pr->dynamic == 1)
112 pr->dynamic = 0x4000;
113 if (pr->port < 2) continue;/* don't have command code yet */
114 if (pr->hostname[1] != 1) {
116 /* Send back a SOCKS 4 error before closing. */
118 memset(data, 0, sizeof(data));
119 data[1] = 91; /* generic `request rejected' */
120 sk_write(pr->s, data, 8);
124 if (pr->port <= 8) continue; /* haven't started user/hostname */
125 if (pr->hostname[pr->port-1] != 0)
126 continue; /* haven't _finished_ user/hostname */
128 * Now we have a full SOCKS 4 request. Check it to
129 * see if it's a SOCKS 4A request.
131 if (pr->hostname[4] == 0 && pr->hostname[5] == 0 &&
132 pr->hostname[6] == 0 && pr->hostname[7] != 0) {
134 * It's SOCKS 4A. So if we haven't yet
135 * collected the host name, we should continue
136 * waiting for data in order to do so; if we
137 * have, we can go ahead.
140 if (pr->dynamic == 0x4000) {
141 pr->dynamic = 0x4001;
142 pr->port = 8; /* reset buffer to overwrite name */
145 pr->hostname[0] = 0; /* reply version code */
146 pr->hostname[1] = 90; /* request granted */
147 sk_write(pr->s, pr->hostname, 8);
149 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
150 memmove(pr->hostname, pr->hostname + 8, len);
154 * It's SOCKS 4, which means we should format
155 * the IP address into the hostname string and
158 pr->hostname[0] = 0; /* reply version code */
159 pr->hostname[1] = 90; /* request granted */
160 sk_write(pr->s, pr->hostname, 8);
161 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
162 sprintf(pr->hostname, "%d.%d.%d.%d",
163 (unsigned char)pr->hostname[4],
164 (unsigned char)pr->hostname[5],
165 (unsigned char)pr->hostname[6],
166 (unsigned char)pr->hostname[7]);
171 if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) &&
172 pr->hostname[0] == 5) {
176 if (pr->dynamic == 1)
177 pr->dynamic = 0x5000;
179 if (pr->dynamic == 0x5000) {
183 * We're receiving a set of method identifiers.
185 if (pr->port < 2) continue;/* no method count yet */
186 if (pr->port < 2 + (unsigned char)pr->hostname[1])
187 continue; /* no methods yet */
188 method = 0xFF; /* invalid */
189 for (i = 0; i < (unsigned char)pr->hostname[1]; i++)
190 if (pr->hostname[2+i] == 0) {
191 method = 0;/* no auth */
196 sk_write(pr->s, data, 2);
197 pr->dynamic = 0x5001;
198 pr->port = 0; /* re-empty the buffer */
202 if (pr->dynamic == 0x5001) {
204 * We're receiving a SOCKS request.
206 unsigned char reply[10]; /* SOCKS5 atyp=1 reply */
210 * Pre-fill reply packet.
211 * In all cases, we set BND.{HOST,ADDR} to 0.0.0.0:0
212 * (atyp=1) in the reply; if we succeed, we don't know
213 * the right answers, and if we fail, they should be
216 memset(reply, 0, lenof(reply));
217 reply[0] = 5; /* VER */
218 reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */
220 if (pr->port < 6) continue;
221 atype = (unsigned char)pr->hostname[3];
222 if (atype == 1) /* IPv4 address */
224 if (atype == 4) /* IPv6 address */
226 if (atype == 3) /* domain name has leading length */
227 alen = 1 + (unsigned char)pr->hostname[4];
228 if (pr->port < 6 + alen) continue;
229 if (pr->hostname[1] != 1 || pr->hostname[2] != 0) {
230 /* Not CONNECT or reserved field nonzero - error */
231 reply[1] = 1; /* generic failure */
232 sk_write(pr->s, (char *) reply, lenof(reply));
237 * Now we have a viable connect request. Switch
240 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen);
242 /* REP=0 (success) already */
243 sk_write(pr->s, (char *) reply, lenof(reply));
244 sprintf(pr->hostname, "%d.%d.%d.%d",
245 (unsigned char)pr->hostname[4],
246 (unsigned char)pr->hostname[5],
247 (unsigned char)pr->hostname[6],
248 (unsigned char)pr->hostname[7]);
250 } else if (atype == 3) {
251 /* REP=0 (success) already */
252 sk_write(pr->s, (char *) reply, lenof(reply));
253 memmove(pr->hostname, pr->hostname + 5, alen-1);
254 pr->hostname[alen-1] = '\0';
258 * Unknown address type. (FIXME: support IPv6!)
260 reply[1] = 8; /* atype not supported */
261 sk_write(pr->s, (char *) reply, lenof(reply));
269 * If we get here without either having done `continue'
270 * or `goto connect', it must be because there is no
271 * sensible interpretation of what's in our buffer. So
272 * close the connection rudely.
280 * We come here when we're ready to make an actual
286 * Freeze the socket until the SSH server confirms the
289 sk_set_frozen(pr->s, 1);
291 pr->c = new_sock_channel(pr->backhandle, pr->s);
296 /* asks to forward to the specified host/port for this */
297 ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
302 * If there's any data remaining in our current buffer,
303 * save it to be sent on pfd_confirm().
306 pr->buffer = snewn(len, char);
307 memcpy(pr->buffer, data, len);
312 if (sshfwd_write(pr->c, data, len) > 0) {
314 sk_set_frozen(pr->s, 1);
320 static void pfd_sent(Plug plug, int bufsize)
322 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
325 sshfwd_unthrottle(pr->c, bufsize);
329 * Called when receiving a PORT OPEN from the server
331 const char *pfd_newconnect(Socket *s, char *hostname, int port,
332 void *c, Conf *conf, int addressfamily)
334 static const struct plug_function_table fn_table = {
344 char *dummy_realhost;
345 struct PFwdPrivate *pr;
350 addr = name_lookup(hostname, port, &dummy_realhost, conf, addressfamily);
351 if ((err = sk_addr_error(addr)) != NULL) {
359 pr = snew(struct PFwdPrivate);
362 pr->throttled = pr->throttle_override = 0;
365 pr->backhandle = NULL; /* we shouldn't need this */
368 pr->s = *s = new_connection(addr, dummy_realhost, port,
369 0, 1, 0, 0, (Plug) pr, conf);
370 if ((err = sk_socket_error(*s)) != NULL) {
375 sk_set_private_ptr(*s, pr);
380 called when someone connects to the local port
383 static int pfd_accepting(Plug p, OSSocket sock)
385 static const struct plug_function_table fn_table = {
392 struct PFwdPrivate *pr, *org;
396 org = (struct PFwdPrivate *)p;
397 pr = snew(struct PFwdPrivate);
402 pr->backhandle = org->backhandle;
404 pr->s = s = sk_register(sock, (Plug) pr);
405 if ((err = sk_socket_error(s)) != NULL) {
410 sk_set_private_ptr(s, pr);
412 pr->throttled = pr->throttle_override = 0;
417 pr->port = 0; /* "hostname" buffer is so far empty */
418 sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */
421 strcpy(pr->hostname, org->hostname);
422 pr->port = org->port;
423 pr->c = new_sock_channel(org->backhandle, s);
429 /* asks to forward to the specified host/port for this */
430 ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
438 /* Add a new forwarding from port -> desthost:destport
439 sets up a listener on the local machine on (srcaddr:)port
441 const char *pfd_addforward(char *desthost, int destport, char *srcaddr,
442 int port, void *backhandle, Conf *conf,
443 void **sockdata, int address_family)
445 static const struct plug_function_table fn_table = {
448 pfd_receive, /* should not happen... */
449 pfd_sent, /* also should not happen */
454 struct PFwdPrivate *pr;
460 pr = snew(struct PFwdPrivate);
465 strcpy(pr->hostname, desthost);
470 pr->throttled = pr->throttle_override = 0;
472 pr->backhandle = backhandle;
474 pr->s = s = new_listener(srcaddr, port, (Plug) pr,
475 !conf_get_int(conf, CONF_lport_acceptall),
476 conf, address_family);
477 if ((err = sk_socket_error(s)) != NULL) {
482 sk_set_private_ptr(s, pr);
484 *sockdata = (void *)s;
489 void pfd_close(Socket s)
491 struct PFwdPrivate *pr;
496 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
505 * Terminate a listener.
507 void pfd_terminate(void *sv)
509 pfd_close((Socket)sv);
512 void pfd_unthrottle(Socket s)
514 struct PFwdPrivate *pr;
517 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
520 sk_set_frozen(s, pr->throttled || pr->throttle_override);
523 void pfd_override_throttle(Socket s, int enable)
525 struct PFwdPrivate *pr;
528 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
530 pr->throttle_override = enable;
531 sk_set_frozen(s, pr->throttled || pr->throttle_override);
535 * Called to send data down the raw connection.
537 int pfd_send(Socket s, char *data, int len)
541 return sk_write(s, data, len);
544 void pfd_send_eof(Socket s)
549 void pfd_confirm(Socket s)
551 struct PFwdPrivate *pr;
556 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
559 sk_write(s, NULL, 0);
561 sshfwd_write(pr->c, pr->buffer, pr->buflen);