14 #define GET_32BIT_LSB_FIRST(cp) \
15 (((unsigned long)(unsigned char)(cp)[0]) | \
16 ((unsigned long)(unsigned char)(cp)[1] << 8) | \
17 ((unsigned long)(unsigned char)(cp)[2] << 16) | \
18 ((unsigned long)(unsigned char)(cp)[3] << 24))
20 #define PUT_32BIT_LSB_FIRST(cp, value) ( \
22 (cp)[1] = (value) >> 8, \
23 (cp)[2] = (value) >> 16, \
24 (cp)[3] = (value) >> 24 )
26 #define GET_16BIT_LSB_FIRST(cp) \
27 (((unsigned long)(unsigned char)(cp)[0]) | \
28 ((unsigned long)(unsigned char)(cp)[1] << 8))
30 #define PUT_16BIT_LSB_FIRST(cp, value) ( \
32 (cp)[1] = (value) >> 8 )
34 #define GET_32BIT_MSB_FIRST(cp) \
35 (((unsigned long)(unsigned char)(cp)[0] << 24) | \
36 ((unsigned long)(unsigned char)(cp)[1] << 16) | \
37 ((unsigned long)(unsigned char)(cp)[2] << 8) | \
38 ((unsigned long)(unsigned char)(cp)[3]))
40 #define PUT_32BIT_MSB_FIRST(cp, value) ( \
41 (cp)[0] = (value) >> 24, \
42 (cp)[1] = (value) >> 16, \
43 (cp)[2] = (value) >> 8, \
46 #define GET_16BIT_MSB_FIRST(cp) \
47 (((unsigned long)(unsigned char)(cp)[0] << 8) | \
48 ((unsigned long)(unsigned char)(cp)[1]))
50 #define PUT_16BIT_MSB_FIRST(cp, value) ( \
51 (cp)[0] = (value) >> 8, \
55 const struct plug_function_table *fn;
56 /* the above variable absolutely *must* be the first in this structure */
57 void *c; /* (channel) data used by ssh.c */
58 void *backhandle; /* instance of SSH backend itself */
59 /* Note that backhandle need not be filled in if c is non-NULL */
61 int throttled, throttle_override;
64 * `dynamic' does double duty. It's set to 0 for an ordinary
65 * forwarded port, and nonzero for SOCKS-style dynamic port
66 * forwarding; but it also represents the state of the SOCKS
71 * `hostname' and `port' are the real hostname and port, once
72 * we know what we're connecting to; they're unused for this
73 * purpose while conducting a local SOCKS exchange, which means
74 * we can also use them as a buffer and pointer for reading
75 * data from the SOCKS client.
80 * When doing dynamic port forwarding, we can receive
81 * connection data before we are actually able to send it; so
82 * we may have to temporarily hold some in a dynamically
83 * allocated buffer here.
89 static int pfd_closing(Plug plug, const char *error_msg, int error_code,
92 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
95 * We have no way to communicate down the forwarded connection,
96 * so if an error occurred on the socket, we just ignore it
97 * and treat it like a proper close.
105 static int pfd_receive(Plug plug, int urgent, char *data, int len)
107 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
111 * Throughout SOCKS negotiation, "hostname" is re-used as a
112 * random protocol buffer with "port" storing the length.
114 if (pr->port >= lenof(pr->hostname)) {
115 /* Request too long. */
116 if ((pr->dynamic >> 12) == 4) {
117 /* Send back a SOCKS 4 error before closing. */
119 memset(data, 0, sizeof(data));
120 data[1] = 91; /* generic `request rejected' */
121 sk_write(pr->s, data, 8);
126 pr->hostname[pr->port++] = *data++;
129 * Now check what's in the buffer to see if it's a
130 * valid and complete message in the SOCKS exchange.
132 if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) &&
133 pr->hostname[0] == 4) {
137 if (pr->dynamic == 1)
138 pr->dynamic = 0x4000;
139 if (pr->port < 2) continue;/* don't have command code yet */
140 if (pr->hostname[1] != 1) {
142 /* Send back a SOCKS 4 error before closing. */
144 memset(data, 0, sizeof(data));
145 data[1] = 91; /* generic `request rejected' */
146 sk_write(pr->s, data, 8);
150 if (pr->port <= 8) continue; /* haven't started user/hostname */
151 if (pr->hostname[pr->port-1] != 0)
152 continue; /* haven't _finished_ user/hostname */
154 * Now we have a full SOCKS 4 request. Check it to
155 * see if it's a SOCKS 4A request.
157 if (pr->hostname[4] == 0 && pr->hostname[5] == 0 &&
158 pr->hostname[6] == 0 && pr->hostname[7] != 0) {
160 * It's SOCKS 4A. So if we haven't yet
161 * collected the host name, we should continue
162 * waiting for data in order to do so; if we
163 * have, we can go ahead.
166 if (pr->dynamic == 0x4000) {
167 pr->dynamic = 0x4001;
168 pr->port = 8; /* reset buffer to overwrite name */
171 pr->hostname[0] = 0; /* reply version code */
172 pr->hostname[1] = 90; /* request granted */
173 sk_write(pr->s, pr->hostname, 8);
175 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
176 memmove(pr->hostname, pr->hostname + 8, len);
180 * It's SOCKS 4, which means we should format
181 * the IP address into the hostname string and
184 pr->hostname[0] = 0; /* reply version code */
185 pr->hostname[1] = 90; /* request granted */
186 sk_write(pr->s, pr->hostname, 8);
187 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
188 sprintf(pr->hostname, "%d.%d.%d.%d",
189 (unsigned char)pr->hostname[4],
190 (unsigned char)pr->hostname[5],
191 (unsigned char)pr->hostname[6],
192 (unsigned char)pr->hostname[7]);
197 if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) &&
198 pr->hostname[0] == 5) {
202 if (pr->dynamic == 1)
203 pr->dynamic = 0x5000;
205 if (pr->dynamic == 0x5000) {
209 * We're receiving a set of method identifiers.
211 if (pr->port < 2) continue;/* no method count yet */
212 if (pr->port < 2 + (unsigned char)pr->hostname[1])
213 continue; /* no methods yet */
214 method = 0xFF; /* invalid */
215 for (i = 0; i < (unsigned char)pr->hostname[1]; i++)
216 if (pr->hostname[2+i] == 0) {
217 method = 0;/* no auth */
222 sk_write(pr->s, data, 2);
223 pr->dynamic = 0x5001;
224 pr->port = 0; /* re-empty the buffer */
228 if (pr->dynamic == 0x5001) {
230 * We're receiving a SOCKS request.
232 unsigned char reply[10]; /* SOCKS5 atyp=1 reply */
236 * Pre-fill reply packet.
237 * In all cases, we set BND.{HOST,ADDR} to 0.0.0.0:0
238 * (atyp=1) in the reply; if we succeed, we don't know
239 * the right answers, and if we fail, they should be
242 memset(reply, 0, lenof(reply));
243 reply[0] = 5; /* VER */
244 reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */
246 if (pr->port < 6) continue;
247 atype = (unsigned char)pr->hostname[3];
248 if (atype == 1) /* IPv4 address */
250 if (atype == 4) /* IPv6 address */
252 if (atype == 3) /* domain name has leading length */
253 alen = 1 + (unsigned char)pr->hostname[4];
254 if (pr->port < 6 + alen) continue;
255 if (pr->hostname[1] != 1 || pr->hostname[2] != 0) {
256 /* Not CONNECT or reserved field nonzero - error */
257 reply[1] = 1; /* generic failure */
258 sk_write(pr->s, (char *) reply, lenof(reply));
263 * Now we have a viable connect request. Switch
266 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen);
268 /* REP=0 (success) already */
269 sk_write(pr->s, (char *) reply, lenof(reply));
270 sprintf(pr->hostname, "%d.%d.%d.%d",
271 (unsigned char)pr->hostname[4],
272 (unsigned char)pr->hostname[5],
273 (unsigned char)pr->hostname[6],
274 (unsigned char)pr->hostname[7]);
276 } else if (atype == 3) {
277 /* REP=0 (success) already */
278 sk_write(pr->s, (char *) reply, lenof(reply));
279 memmove(pr->hostname, pr->hostname + 5, alen-1);
280 pr->hostname[alen-1] = '\0';
284 * Unknown address type. (FIXME: support IPv6!)
286 reply[1] = 8; /* atype not supported */
287 sk_write(pr->s, (char *) reply, lenof(reply));
295 * If we get here without either having done `continue'
296 * or `goto connect', it must be because there is no
297 * sensible interpretation of what's in our buffer. So
298 * close the connection rudely.
306 * We come here when we're ready to make an actual
311 pr->c = new_sock_channel(pr->backhandle, pr->s);
316 /* asks to forward to the specified host/port for this */
317 ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
322 * Now freeze the socket until the SSH server confirms the
325 sk_set_frozen(pr->s, 1);
327 * If there's any data remaining in our current buffer,
328 * save it to be sent on pfd_confirm().
331 pr->buffer = snewn(len, char);
332 memcpy(pr->buffer, data, len);
337 if (sshfwd_write(pr->c, data, len) > 0) {
339 sk_set_frozen(pr->s, 1);
345 static void pfd_sent(Plug plug, int bufsize)
347 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
350 sshfwd_unthrottle(pr->c, bufsize);
354 * Called when receiving a PORT OPEN from the server
356 const char *pfd_newconnect(Socket *s, char *hostname, int port,
357 void *c, const Config *cfg)
359 static const struct plug_function_table fn_table = {
368 char *dummy_realhost;
369 struct PFwdPrivate *pr;
374 addr = name_lookup(hostname, port, &dummy_realhost, cfg);
375 if ((err = sk_addr_error(addr)) != NULL) {
383 pr = snew(struct PFwdPrivate);
386 pr->throttled = pr->throttle_override = 0;
389 pr->backhandle = NULL; /* we shouldn't need this */
392 pr->s = *s = new_connection(addr, dummy_realhost, port,
393 0, 1, 0, 0, (Plug) pr, cfg);
394 if ((err = sk_socket_error(*s)) != NULL) {
399 sk_set_private_ptr(*s, pr);
404 called when someone connects to the local port
407 static int pfd_accepting(Plug p, OSSocket sock)
409 static const struct plug_function_table fn_table = {
415 struct PFwdPrivate *pr, *org;
419 org = (struct PFwdPrivate *)p;
420 pr = snew(struct PFwdPrivate);
425 pr->backhandle = org->backhandle;
427 pr->s = s = sk_register(sock, (Plug) pr);
428 if ((err = sk_socket_error(s)) != NULL) {
433 sk_set_private_ptr(s, pr);
435 pr->throttled = pr->throttle_override = 0;
440 pr->port = 0; /* "hostname" buffer is so far empty */
441 sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */
444 strcpy(pr->hostname, org->hostname);
445 pr->port = org->port;
446 pr->c = new_sock_channel(org->backhandle, s);
452 /* asks to forward to the specified host/port for this */
453 ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
461 /* Add a new forwarding from port -> desthost:destport
462 sets up a listener on the local machine on (srcaddr:)port
464 const char *pfd_addforward(char *desthost, int destport, char *srcaddr,
465 int port, void *backhandle, const Config *cfg)
467 static const struct plug_function_table fn_table = {
469 pfd_receive, /* should not happen... */
470 pfd_sent, /* also should not happen */
475 struct PFwdPrivate *pr;
481 pr = snew(struct PFwdPrivate);
486 strcpy(pr->hostname, desthost);
491 pr->throttled = pr->throttle_override = 0;
493 pr->backhandle = backhandle;
495 pr->s = s = new_listener(srcaddr, port, (Plug) pr,
496 !cfg->lport_acceptall, cfg);
497 if ((err = sk_socket_error(s)) != NULL) {
502 sk_set_private_ptr(s, pr);
507 void pfd_close(Socket s)
509 struct PFwdPrivate *pr;
514 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
522 void pfd_unthrottle(Socket s)
524 struct PFwdPrivate *pr;
527 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
530 sk_set_frozen(s, pr->throttled || pr->throttle_override);
533 void pfd_override_throttle(Socket s, int enable)
535 struct PFwdPrivate *pr;
538 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
540 pr->throttle_override = enable;
541 sk_set_frozen(s, pr->throttled || pr->throttle_override);
545 * Called to send data down the raw connection.
547 int pfd_send(Socket s, char *data, int len)
551 return sk_write(s, data, len);
555 void pfd_confirm(Socket s)
557 struct PFwdPrivate *pr;
562 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
565 sk_write(s, NULL, 0);
567 sshfwd_write(pr->c, pr->buffer, pr->buflen);