eaf1e20a |
1 | /* |
2 | * SSH port forwarding. |
3 | */ |
4 | |
f26d5c33 |
5 | #include <stdio.h> |
6 | #include <stdlib.h> |
7 | |
8 | #include "putty.h" |
9 | #include "ssh.h" |
10 | |
11 | #ifndef FALSE |
12 | #define FALSE 0 |
13 | #endif |
14 | #ifndef TRUE |
15 | #define TRUE 1 |
16 | #endif |
17 | |
f26d5c33 |
18 | struct PFwdPrivate { |
c85623f9 |
19 | const struct plug_function_table *fn; |
f26d5c33 |
20 | /* the above variable absolutely *must* be the first in this structure */ |
21 | void *c; /* (channel) data used by ssh.c */ |
6b78788a |
22 | void *backhandle; /* instance of SSH backend itself */ |
23 | /* Note that backhandle need not be filled in if c is non-NULL */ |
f26d5c33 |
24 | Socket s; |
5471d09a |
25 | int throttled, throttle_override; |
f26d5c33 |
26 | int ready; |
820ebe3b |
27 | /* |
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 |
31 | * exchange. |
32 | */ |
33 | int dynamic; |
34 | /* |
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. |
40 | */ |
fab893b6 |
41 | char hostname[256+8]; |
820ebe3b |
42 | int port; |
43 | /* |
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. |
48 | */ |
49 | void *buffer; |
50 | int buflen; |
f26d5c33 |
51 | }; |
52 | |
7555d6a5 |
53 | static void pfd_log(Plug plug, int type, SockAddr addr, int port, |
54 | const char *error_msg, int error_code) |
55 | { |
56 | /* we have to dump these since we have no interface to logging.c */ |
57 | } |
58 | |
cbe2d68f |
59 | static int pfd_closing(Plug plug, const char *error_msg, int error_code, |
f26d5c33 |
60 | int calling_back) |
61 | { |
62 | struct PFwdPrivate *pr = (struct PFwdPrivate *) plug; |
63 | |
64 | /* |
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. |
68 | */ |
820ebe3b |
69 | if (pr->c) |
70 | sshfwd_close(pr->c); |
f26d5c33 |
71 | pfd_close(pr->s); |
72 | return 1; |
73 | } |
74 | |
75 | static int pfd_receive(Plug plug, int urgent, char *data, int len) |
76 | { |
77 | struct PFwdPrivate *pr = (struct PFwdPrivate *) plug; |
820ebe3b |
78 | if (pr->dynamic) { |
79 | while (len--) { |
b8a98e25 |
80 | /* |
81 | * Throughout SOCKS negotiation, "hostname" is re-used as a |
82 | * random protocol buffer with "port" storing the length. |
83 | */ |
820ebe3b |
84 | if (pr->port >= lenof(pr->hostname)) { |
04df1251 |
85 | /* Request too long. */ |
820ebe3b |
86 | if ((pr->dynamic >> 12) == 4) { |
87 | /* Send back a SOCKS 4 error before closing. */ |
88 | char data[8]; |
89 | memset(data, 0, sizeof(data)); |
90 | data[1] = 91; /* generic `request rejected' */ |
91 | sk_write(pr->s, data, 8); |
92 | } |
93 | pfd_close(pr->s); |
94 | return 1; |
95 | } |
96 | pr->hostname[pr->port++] = *data++; |
97 | |
98 | /* |
99 | * Now check what's in the buffer to see if it's a |
100 | * valid and complete message in the SOCKS exchange. |
101 | */ |
102 | if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) && |
103 | pr->hostname[0] == 4) { |
104 | /* |
105 | * SOCKS 4. |
106 | */ |
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) { |
b8a98e25 |
111 | /* Not CONNECT. */ |
820ebe3b |
112 | /* Send back a SOCKS 4 error before closing. */ |
113 | char data[8]; |
114 | memset(data, 0, sizeof(data)); |
115 | data[1] = 91; /* generic `request rejected' */ |
116 | sk_write(pr->s, data, 8); |
117 | pfd_close(pr->s); |
118 | return 1; |
119 | } |
b8a98e25 |
120 | if (pr->port <= 8) continue; /* haven't started user/hostname */ |
820ebe3b |
121 | if (pr->hostname[pr->port-1] != 0) |
b8a98e25 |
122 | continue; /* haven't _finished_ user/hostname */ |
820ebe3b |
123 | /* |
124 | * Now we have a full SOCKS 4 request. Check it to |
125 | * see if it's a SOCKS 4A request. |
126 | */ |
127 | if (pr->hostname[4] == 0 && pr->hostname[5] == 0 && |
128 | pr->hostname[6] == 0 && pr->hostname[7] != 0) { |
129 | /* |
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. |
134 | */ |
135 | int len; |
136 | if (pr->dynamic == 0x4000) { |
137 | pr->dynamic = 0x4001; |
fab893b6 |
138 | pr->port = 8; /* reset buffer to overwrite name */ |
820ebe3b |
139 | continue; |
140 | } |
141 | pr->hostname[0] = 0; /* reply version code */ |
142 | pr->hostname[1] = 90; /* request granted */ |
143 | sk_write(pr->s, pr->hostname, 8); |
b8a98e25 |
144 | len= pr->port - 8; |
820ebe3b |
145 | pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2); |
fab893b6 |
146 | memmove(pr->hostname, pr->hostname + 8, len); |
820ebe3b |
147 | goto connect; |
148 | } else { |
149 | /* |
150 | * It's SOCKS 4, which means we should format |
151 | * the IP address into the hostname string and |
152 | * then just go. |
153 | */ |
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]); |
163 | goto connect; |
164 | } |
165 | } |
166 | |
167 | if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) && |
168 | pr->hostname[0] == 5) { |
169 | /* |
170 | * SOCKS 5. |
171 | */ |
172 | if (pr->dynamic == 1) |
173 | pr->dynamic = 0x5000; |
174 | |
175 | if (pr->dynamic == 0x5000) { |
176 | int i, method; |
177 | char data[2]; |
178 | /* |
179 | * We're receiving a set of method identifiers. |
180 | */ |
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 */ |
188 | break; |
189 | } |
190 | data[0] = 5; |
191 | data[1] = method; |
192 | sk_write(pr->s, data, 2); |
193 | pr->dynamic = 0x5001; |
194 | pr->port = 0; /* re-empty the buffer */ |
195 | continue; |
196 | } |
197 | |
198 | if (pr->dynamic == 0x5001) { |
04df1251 |
199 | /* |
200 | * We're receiving a SOCKS request. |
201 | */ |
202 | unsigned char reply[10]; /* SOCKS5 atyp=1 reply */ |
4797387c |
203 | int atype, alen = 0; |
04df1251 |
204 | |
205 | /* |
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 |
210 | * ignored. |
211 | */ |
212 | memset(reply, 0, lenof(reply)); |
213 | reply[0] = 5; /* VER */ |
214 | reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */ |
215 | |
820ebe3b |
216 | if (pr->port < 6) continue; |
217 | atype = (unsigned char)pr->hostname[3]; |
218 | if (atype == 1) /* IPv4 address */ |
219 | alen = 4; |
220 | if (atype == 4) /* IPv6 address */ |
221 | alen = 16; |
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) { |
04df1251 |
226 | /* Not CONNECT or reserved field nonzero - error */ |
227 | reply[1] = 1; /* generic failure */ |
776792d7 |
228 | sk_write(pr->s, (char *) reply, lenof(reply)); |
820ebe3b |
229 | pfd_close(pr->s); |
230 | return 1; |
231 | } |
232 | /* |
233 | * Now we have a viable connect request. Switch |
234 | * on atype. |
235 | */ |
236 | pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen); |
237 | if (atype == 1) { |
04df1251 |
238 | /* REP=0 (success) already */ |
776792d7 |
239 | sk_write(pr->s, (char *) reply, lenof(reply)); |
820ebe3b |
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]); |
245 | goto connect; |
246 | } else if (atype == 3) { |
04df1251 |
247 | /* REP=0 (success) already */ |
776792d7 |
248 | sk_write(pr->s, (char *) reply, lenof(reply)); |
820ebe3b |
249 | memmove(pr->hostname, pr->hostname + 5, alen-1); |
250 | pr->hostname[alen-1] = '\0'; |
251 | goto connect; |
252 | } else { |
253 | /* |
254 | * Unknown address type. (FIXME: support IPv6!) |
255 | */ |
04df1251 |
256 | reply[1] = 8; /* atype not supported */ |
776792d7 |
257 | sk_write(pr->s, (char *) reply, lenof(reply)); |
820ebe3b |
258 | pfd_close(pr->s); |
776792d7 |
259 | return 1; |
820ebe3b |
260 | } |
261 | } |
262 | } |
776792d7 |
263 | |
820ebe3b |
264 | /* |
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. |
269 | */ |
270 | pfd_close(pr->s); |
271 | return 1; |
272 | } |
273 | return 1; |
274 | |
275 | /* |
276 | * We come here when we're ready to make an actual |
277 | * connection. |
278 | */ |
279 | connect: |
280 | |
09d133f3 |
281 | /* |
282 | * Freeze the socket until the SSH server confirms the |
283 | * connection. |
284 | */ |
285 | sk_set_frozen(pr->s, 1); |
286 | |
820ebe3b |
287 | pr->c = new_sock_channel(pr->backhandle, pr->s); |
288 | if (pr->c == NULL) { |
289 | pfd_close(pr->s); |
290 | return 1; |
291 | } else { |
292 | /* asks to forward to the specified host/port for this */ |
293 | ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding"); |
294 | } |
295 | pr->dynamic = 0; |
296 | |
297 | /* |
820ebe3b |
298 | * If there's any data remaining in our current buffer, |
299 | * save it to be sent on pfd_confirm(). |
300 | */ |
301 | if (len > 0) { |
302 | pr->buffer = snewn(len, char); |
303 | memcpy(pr->buffer, data, len); |
304 | pr->buflen = len; |
305 | } |
306 | } |
5471d09a |
307 | if (pr->ready) { |
308 | if (sshfwd_write(pr->c, data, len) > 0) { |
309 | pr->throttled = 1; |
310 | sk_set_frozen(pr->s, 1); |
311 | } |
312 | } |
f26d5c33 |
313 | return 1; |
314 | } |
315 | |
5471d09a |
316 | static void pfd_sent(Plug plug, int bufsize) |
317 | { |
318 | struct PFwdPrivate *pr = (struct PFwdPrivate *) plug; |
319 | |
820ebe3b |
320 | if (pr->c) |
321 | sshfwd_unthrottle(pr->c, bufsize); |
5471d09a |
322 | } |
323 | |
f26d5c33 |
324 | /* |
325 | * Called when receiving a PORT OPEN from the server |
326 | */ |
cbe2d68f |
327 | const char *pfd_newconnect(Socket *s, char *hostname, int port, |
4a693cfc |
328 | void *c, Conf *conf, int addressfamily) |
f26d5c33 |
329 | { |
c85623f9 |
330 | static const struct plug_function_table fn_table = { |
7555d6a5 |
331 | pfd_log, |
f26d5c33 |
332 | pfd_closing, |
333 | pfd_receive, |
5471d09a |
334 | pfd_sent, |
f26d5c33 |
335 | NULL |
336 | }; |
337 | |
338 | SockAddr addr; |
cbe2d68f |
339 | const char *err; |
340 | char *dummy_realhost; |
f26d5c33 |
341 | struct PFwdPrivate *pr; |
342 | |
343 | /* |
344 | * Try to find host. |
345 | */ |
4a693cfc |
346 | addr = name_lookup(hostname, port, &dummy_realhost, conf, addressfamily); |
f85e6f6e |
347 | if ((err = sk_addr_error(addr)) != NULL) { |
348 | sk_addr_free(addr); |
f26d5c33 |
349 | return err; |
f85e6f6e |
350 | } |
f26d5c33 |
351 | |
352 | /* |
353 | * Open socket. |
354 | */ |
3d88e64d |
355 | pr = snew(struct PFwdPrivate); |
820ebe3b |
356 | pr->buffer = NULL; |
f26d5c33 |
357 | pr->fn = &fn_table; |
5471d09a |
358 | pr->throttled = pr->throttle_override = 0; |
f26d5c33 |
359 | pr->ready = 1; |
360 | pr->c = c; |
6b78788a |
361 | pr->backhandle = NULL; /* we shouldn't need this */ |
4b42e4f6 |
362 | pr->dynamic = 0; |
f26d5c33 |
363 | |
e8fa8f62 |
364 | pr->s = *s = new_connection(addr, dummy_realhost, port, |
4a693cfc |
365 | 0, 1, 0, 0, (Plug) pr, conf); |
808c3834 |
366 | if ((err = sk_socket_error(*s)) != NULL) { |
f26d5c33 |
367 | sfree(pr); |
368 | return err; |
369 | } |
370 | |
371 | sk_set_private_ptr(*s, pr); |
f26d5c33 |
372 | return NULL; |
373 | } |
374 | |
375 | /* |
376 | called when someone connects to the local port |
377 | */ |
378 | |
f7f9fb5c |
379 | static int pfd_accepting(Plug p, OSSocket sock) |
f26d5c33 |
380 | { |
c85623f9 |
381 | static const struct plug_function_table fn_table = { |
7555d6a5 |
382 | pfd_log, |
f26d5c33 |
383 | pfd_closing, |
384 | pfd_receive, |
5471d09a |
385 | pfd_sent, |
f26d5c33 |
386 | NULL |
387 | }; |
388 | struct PFwdPrivate *pr, *org; |
f26d5c33 |
389 | Socket s; |
cbe2d68f |
390 | const char *err; |
f26d5c33 |
391 | |
f26d5c33 |
392 | org = (struct PFwdPrivate *)p; |
3d88e64d |
393 | pr = snew(struct PFwdPrivate); |
820ebe3b |
394 | pr->buffer = NULL; |
f26d5c33 |
395 | pr->fn = &fn_table; |
396 | |
397 | pr->c = NULL; |
6b78788a |
398 | pr->backhandle = org->backhandle; |
f26d5c33 |
399 | |
400 | pr->s = s = sk_register(sock, (Plug) pr); |
808c3834 |
401 | if ((err = sk_socket_error(s)) != NULL) { |
f26d5c33 |
402 | sfree(pr); |
403 | return err != NULL; |
404 | } |
405 | |
820ebe3b |
406 | sk_set_private_ptr(s, pr); |
f26d5c33 |
407 | |
5471d09a |
408 | pr->throttled = pr->throttle_override = 0; |
f26d5c33 |
409 | pr->ready = 0; |
f26d5c33 |
410 | |
820ebe3b |
411 | if (org->dynamic) { |
412 | pr->dynamic = 1; |
b8a98e25 |
413 | pr->port = 0; /* "hostname" buffer is so far empty */ |
820ebe3b |
414 | sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */ |
f26d5c33 |
415 | } else { |
4b42e4f6 |
416 | pr->dynamic = 0; |
820ebe3b |
417 | strcpy(pr->hostname, org->hostname); |
418 | pr->port = org->port; |
419 | pr->c = new_sock_channel(org->backhandle, s); |
420 | |
421 | if (pr->c == NULL) { |
422 | sfree(pr); |
423 | return 1; |
424 | } else { |
425 | /* asks to forward to the specified host/port for this */ |
426 | ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding"); |
427 | } |
f26d5c33 |
428 | } |
429 | |
430 | return 0; |
431 | } |
432 | |
433 | |
434 | /* Add a new forwarding from port -> desthost:destport |
6ee9b735 |
435 | sets up a listener on the local machine on (srcaddr:)port |
f26d5c33 |
436 | */ |
cbe2d68f |
437 | const char *pfd_addforward(char *desthost, int destport, char *srcaddr, |
4a693cfc |
438 | int port, void *backhandle, Conf *conf, |
05581745 |
439 | void **sockdata, int address_family) |
f26d5c33 |
440 | { |
c85623f9 |
441 | static const struct plug_function_table fn_table = { |
7555d6a5 |
442 | pfd_log, |
f26d5c33 |
443 | pfd_closing, |
5471d09a |
444 | pfd_receive, /* should not happen... */ |
445 | pfd_sent, /* also should not happen */ |
f26d5c33 |
446 | pfd_accepting |
447 | }; |
448 | |
cbe2d68f |
449 | const char *err; |
f26d5c33 |
450 | struct PFwdPrivate *pr; |
451 | Socket s; |
452 | |
453 | /* |
454 | * Open socket. |
455 | */ |
3d88e64d |
456 | pr = snew(struct PFwdPrivate); |
820ebe3b |
457 | pr->buffer = NULL; |
f26d5c33 |
458 | pr->fn = &fn_table; |
459 | pr->c = NULL; |
820ebe3b |
460 | if (desthost) { |
461 | strcpy(pr->hostname, desthost); |
462 | pr->port = destport; |
463 | pr->dynamic = 0; |
464 | } else |
465 | pr->dynamic = 1; |
5471d09a |
466 | pr->throttled = pr->throttle_override = 0; |
f26d5c33 |
467 | pr->ready = 0; |
6b78788a |
468 | pr->backhandle = backhandle; |
f26d5c33 |
469 | |
e8fa8f62 |
470 | pr->s = s = new_listener(srcaddr, port, (Plug) pr, |
4a693cfc |
471 | !conf_get_int(conf, CONF_lport_acceptall), |
472 | conf, address_family); |
808c3834 |
473 | if ((err = sk_socket_error(s)) != NULL) { |
f26d5c33 |
474 | sfree(pr); |
475 | return err; |
476 | } |
477 | |
478 | sk_set_private_ptr(s, pr); |
479 | |
fda2feb1 |
480 | *sockdata = (void *)s; |
481 | |
f26d5c33 |
482 | return NULL; |
483 | } |
484 | |
485 | void pfd_close(Socket s) |
486 | { |
487 | struct PFwdPrivate *pr; |
488 | |
489 | if (!s) |
490 | return; |
491 | |
492 | pr = (struct PFwdPrivate *) sk_get_private_ptr(s); |
493 | |
820ebe3b |
494 | sfree(pr->buffer); |
f26d5c33 |
495 | sfree(pr); |
496 | |
497 | sk_close(s); |
498 | } |
499 | |
fda2feb1 |
500 | /* |
501 | * Terminate a listener. |
502 | */ |
503 | void pfd_terminate(void *sv) |
504 | { |
505 | pfd_close((Socket)sv); |
506 | } |
507 | |
5471d09a |
508 | void pfd_unthrottle(Socket s) |
509 | { |
510 | struct PFwdPrivate *pr; |
511 | if (!s) |
512 | return; |
513 | pr = (struct PFwdPrivate *) sk_get_private_ptr(s); |
514 | |
515 | pr->throttled = 0; |
516 | sk_set_frozen(s, pr->throttled || pr->throttle_override); |
517 | } |
518 | |
519 | void pfd_override_throttle(Socket s, int enable) |
520 | { |
521 | struct PFwdPrivate *pr; |
522 | if (!s) |
523 | return; |
524 | pr = (struct PFwdPrivate *) sk_get_private_ptr(s); |
525 | |
526 | pr->throttle_override = enable; |
527 | sk_set_frozen(s, pr->throttled || pr->throttle_override); |
528 | } |
529 | |
f26d5c33 |
530 | /* |
531 | * Called to send data down the raw connection. |
532 | */ |
5471d09a |
533 | int pfd_send(Socket s, char *data, int len) |
f26d5c33 |
534 | { |
f26d5c33 |
535 | if (s == NULL) |
5471d09a |
536 | return 0; |
537 | return sk_write(s, data, len); |
f26d5c33 |
538 | } |
539 | |
540 | |
541 | void pfd_confirm(Socket s) |
542 | { |
5f2e19fc |
543 | struct PFwdPrivate *pr; |
f26d5c33 |
544 | |
545 | if (s == NULL) |
546 | return; |
547 | |
5f2e19fc |
548 | pr = (struct PFwdPrivate *) sk_get_private_ptr(s); |
f26d5c33 |
549 | pr->ready = 1; |
550 | sk_set_frozen(s, 0); |
551 | sk_write(s, NULL, 0); |
820ebe3b |
552 | if (pr->buffer) { |
553 | sshfwd_write(pr->c, pr->buffer, pr->buflen); |
554 | sfree(pr->buffer); |
555 | pr->buffer = NULL; |
556 | } |
f26d5c33 |
557 | } |