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 | |
c6b41791 |
64 | if (error_msg) { |
65 | /* |
66 | * Socket error. Slam the connection instantly shut. |
67 | */ |
68 | sshfwd_unclean_close(pr->c); |
69 | } else { |
70 | /* |
71 | * Ordinary EOF received on socket. Send an EOF on the SSH |
72 | * channel. |
73 | */ |
74 | if (pr->c) |
75 | sshfwd_write_eof(pr->c); |
76 | } |
bc06669b |
77 | |
f26d5c33 |
78 | return 1; |
79 | } |
80 | |
81 | static int pfd_receive(Plug plug, int urgent, char *data, int len) |
82 | { |
83 | struct PFwdPrivate *pr = (struct PFwdPrivate *) plug; |
820ebe3b |
84 | if (pr->dynamic) { |
85 | while (len--) { |
b8a98e25 |
86 | /* |
87 | * Throughout SOCKS negotiation, "hostname" is re-used as a |
88 | * random protocol buffer with "port" storing the length. |
89 | */ |
820ebe3b |
90 | if (pr->port >= lenof(pr->hostname)) { |
04df1251 |
91 | /* Request too long. */ |
820ebe3b |
92 | if ((pr->dynamic >> 12) == 4) { |
93 | /* Send back a SOCKS 4 error before closing. */ |
94 | char data[8]; |
95 | memset(data, 0, sizeof(data)); |
96 | data[1] = 91; /* generic `request rejected' */ |
97 | sk_write(pr->s, data, 8); |
98 | } |
99 | pfd_close(pr->s); |
100 | return 1; |
101 | } |
102 | pr->hostname[pr->port++] = *data++; |
103 | |
104 | /* |
105 | * Now check what's in the buffer to see if it's a |
106 | * valid and complete message in the SOCKS exchange. |
107 | */ |
108 | if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) && |
109 | pr->hostname[0] == 4) { |
110 | /* |
111 | * SOCKS 4. |
112 | */ |
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) { |
b8a98e25 |
117 | /* Not CONNECT. */ |
820ebe3b |
118 | /* Send back a SOCKS 4 error before closing. */ |
119 | char data[8]; |
120 | memset(data, 0, sizeof(data)); |
121 | data[1] = 91; /* generic `request rejected' */ |
122 | sk_write(pr->s, data, 8); |
123 | pfd_close(pr->s); |
124 | return 1; |
125 | } |
b8a98e25 |
126 | if (pr->port <= 8) continue; /* haven't started user/hostname */ |
820ebe3b |
127 | if (pr->hostname[pr->port-1] != 0) |
b8a98e25 |
128 | continue; /* haven't _finished_ user/hostname */ |
820ebe3b |
129 | /* |
130 | * Now we have a full SOCKS 4 request. Check it to |
131 | * see if it's a SOCKS 4A request. |
132 | */ |
133 | if (pr->hostname[4] == 0 && pr->hostname[5] == 0 && |
134 | pr->hostname[6] == 0 && pr->hostname[7] != 0) { |
135 | /* |
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. |
140 | */ |
141 | int len; |
142 | if (pr->dynamic == 0x4000) { |
143 | pr->dynamic = 0x4001; |
fab893b6 |
144 | pr->port = 8; /* reset buffer to overwrite name */ |
820ebe3b |
145 | continue; |
146 | } |
147 | pr->hostname[0] = 0; /* reply version code */ |
148 | pr->hostname[1] = 90; /* request granted */ |
149 | sk_write(pr->s, pr->hostname, 8); |
b8a98e25 |
150 | len= pr->port - 8; |
820ebe3b |
151 | pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2); |
fab893b6 |
152 | memmove(pr->hostname, pr->hostname + 8, len); |
820ebe3b |
153 | goto connect; |
154 | } else { |
155 | /* |
156 | * It's SOCKS 4, which means we should format |
157 | * the IP address into the hostname string and |
158 | * then just go. |
159 | */ |
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]); |
169 | goto connect; |
170 | } |
171 | } |
172 | |
173 | if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) && |
174 | pr->hostname[0] == 5) { |
175 | /* |
176 | * SOCKS 5. |
177 | */ |
178 | if (pr->dynamic == 1) |
179 | pr->dynamic = 0x5000; |
180 | |
181 | if (pr->dynamic == 0x5000) { |
182 | int i, method; |
183 | char data[2]; |
184 | /* |
185 | * We're receiving a set of method identifiers. |
186 | */ |
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 */ |
194 | break; |
195 | } |
196 | data[0] = 5; |
197 | data[1] = method; |
198 | sk_write(pr->s, data, 2); |
199 | pr->dynamic = 0x5001; |
200 | pr->port = 0; /* re-empty the buffer */ |
201 | continue; |
202 | } |
203 | |
204 | if (pr->dynamic == 0x5001) { |
04df1251 |
205 | /* |
206 | * We're receiving a SOCKS request. |
207 | */ |
208 | unsigned char reply[10]; /* SOCKS5 atyp=1 reply */ |
4797387c |
209 | int atype, alen = 0; |
04df1251 |
210 | |
211 | /* |
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 |
216 | * ignored. |
217 | */ |
218 | memset(reply, 0, lenof(reply)); |
219 | reply[0] = 5; /* VER */ |
220 | reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */ |
221 | |
820ebe3b |
222 | if (pr->port < 6) continue; |
223 | atype = (unsigned char)pr->hostname[3]; |
224 | if (atype == 1) /* IPv4 address */ |
225 | alen = 4; |
226 | if (atype == 4) /* IPv6 address */ |
227 | alen = 16; |
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) { |
04df1251 |
232 | /* Not CONNECT or reserved field nonzero - error */ |
233 | reply[1] = 1; /* generic failure */ |
776792d7 |
234 | sk_write(pr->s, (char *) reply, lenof(reply)); |
820ebe3b |
235 | pfd_close(pr->s); |
236 | return 1; |
237 | } |
238 | /* |
239 | * Now we have a viable connect request. Switch |
240 | * on atype. |
241 | */ |
242 | pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen); |
243 | if (atype == 1) { |
04df1251 |
244 | /* REP=0 (success) already */ |
776792d7 |
245 | sk_write(pr->s, (char *) reply, lenof(reply)); |
820ebe3b |
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]); |
251 | goto connect; |
252 | } else if (atype == 3) { |
04df1251 |
253 | /* REP=0 (success) already */ |
776792d7 |
254 | sk_write(pr->s, (char *) reply, lenof(reply)); |
820ebe3b |
255 | memmove(pr->hostname, pr->hostname + 5, alen-1); |
256 | pr->hostname[alen-1] = '\0'; |
257 | goto connect; |
258 | } else { |
259 | /* |
260 | * Unknown address type. (FIXME: support IPv6!) |
261 | */ |
04df1251 |
262 | reply[1] = 8; /* atype not supported */ |
776792d7 |
263 | sk_write(pr->s, (char *) reply, lenof(reply)); |
820ebe3b |
264 | pfd_close(pr->s); |
776792d7 |
265 | return 1; |
820ebe3b |
266 | } |
267 | } |
268 | } |
776792d7 |
269 | |
820ebe3b |
270 | /* |
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. |
275 | */ |
276 | pfd_close(pr->s); |
277 | return 1; |
278 | } |
279 | return 1; |
280 | |
281 | /* |
282 | * We come here when we're ready to make an actual |
283 | * connection. |
284 | */ |
285 | connect: |
286 | |
09d133f3 |
287 | /* |
288 | * Freeze the socket until the SSH server confirms the |
289 | * connection. |
290 | */ |
291 | sk_set_frozen(pr->s, 1); |
292 | |
820ebe3b |
293 | pr->c = new_sock_channel(pr->backhandle, pr->s); |
294 | if (pr->c == NULL) { |
295 | pfd_close(pr->s); |
296 | return 1; |
297 | } else { |
298 | /* asks to forward to the specified host/port for this */ |
299 | ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding"); |
300 | } |
301 | pr->dynamic = 0; |
302 | |
303 | /* |
820ebe3b |
304 | * If there's any data remaining in our current buffer, |
305 | * save it to be sent on pfd_confirm(). |
306 | */ |
307 | if (len > 0) { |
308 | pr->buffer = snewn(len, char); |
309 | memcpy(pr->buffer, data, len); |
310 | pr->buflen = len; |
311 | } |
312 | } |
5471d09a |
313 | if (pr->ready) { |
314 | if (sshfwd_write(pr->c, data, len) > 0) { |
315 | pr->throttled = 1; |
316 | sk_set_frozen(pr->s, 1); |
317 | } |
318 | } |
f26d5c33 |
319 | return 1; |
320 | } |
321 | |
5471d09a |
322 | static void pfd_sent(Plug plug, int bufsize) |
323 | { |
324 | struct PFwdPrivate *pr = (struct PFwdPrivate *) plug; |
325 | |
820ebe3b |
326 | if (pr->c) |
327 | sshfwd_unthrottle(pr->c, bufsize); |
5471d09a |
328 | } |
329 | |
f26d5c33 |
330 | /* |
331 | * Called when receiving a PORT OPEN from the server |
332 | */ |
cbe2d68f |
333 | const char *pfd_newconnect(Socket *s, char *hostname, int port, |
4a693cfc |
334 | void *c, Conf *conf, int addressfamily) |
f26d5c33 |
335 | { |
c85623f9 |
336 | static const struct plug_function_table fn_table = { |
7555d6a5 |
337 | pfd_log, |
f26d5c33 |
338 | pfd_closing, |
339 | pfd_receive, |
5471d09a |
340 | pfd_sent, |
f26d5c33 |
341 | NULL |
342 | }; |
343 | |
344 | SockAddr addr; |
cbe2d68f |
345 | const char *err; |
346 | char *dummy_realhost; |
f26d5c33 |
347 | struct PFwdPrivate *pr; |
348 | |
349 | /* |
350 | * Try to find host. |
351 | */ |
4a693cfc |
352 | addr = name_lookup(hostname, port, &dummy_realhost, conf, addressfamily); |
f85e6f6e |
353 | if ((err = sk_addr_error(addr)) != NULL) { |
354 | sk_addr_free(addr); |
f26d5c33 |
355 | return err; |
f85e6f6e |
356 | } |
f26d5c33 |
357 | |
358 | /* |
359 | * Open socket. |
360 | */ |
3d88e64d |
361 | pr = snew(struct PFwdPrivate); |
820ebe3b |
362 | pr->buffer = NULL; |
f26d5c33 |
363 | pr->fn = &fn_table; |
5471d09a |
364 | pr->throttled = pr->throttle_override = 0; |
f26d5c33 |
365 | pr->ready = 1; |
366 | pr->c = c; |
6b78788a |
367 | pr->backhandle = NULL; /* we shouldn't need this */ |
4b42e4f6 |
368 | pr->dynamic = 0; |
f26d5c33 |
369 | |
e8fa8f62 |
370 | pr->s = *s = new_connection(addr, dummy_realhost, port, |
4a693cfc |
371 | 0, 1, 0, 0, (Plug) pr, conf); |
808c3834 |
372 | if ((err = sk_socket_error(*s)) != NULL) { |
f26d5c33 |
373 | sfree(pr); |
374 | return err; |
375 | } |
376 | |
377 | sk_set_private_ptr(*s, pr); |
f26d5c33 |
378 | return NULL; |
379 | } |
380 | |
381 | /* |
382 | called when someone connects to the local port |
383 | */ |
384 | |
f7f9fb5c |
385 | static int pfd_accepting(Plug p, OSSocket sock) |
f26d5c33 |
386 | { |
c85623f9 |
387 | static const struct plug_function_table fn_table = { |
7555d6a5 |
388 | pfd_log, |
f26d5c33 |
389 | pfd_closing, |
390 | pfd_receive, |
5471d09a |
391 | pfd_sent, |
f26d5c33 |
392 | NULL |
393 | }; |
394 | struct PFwdPrivate *pr, *org; |
f26d5c33 |
395 | Socket s; |
cbe2d68f |
396 | const char *err; |
f26d5c33 |
397 | |
f26d5c33 |
398 | org = (struct PFwdPrivate *)p; |
3d88e64d |
399 | pr = snew(struct PFwdPrivate); |
820ebe3b |
400 | pr->buffer = NULL; |
f26d5c33 |
401 | pr->fn = &fn_table; |
402 | |
403 | pr->c = NULL; |
6b78788a |
404 | pr->backhandle = org->backhandle; |
f26d5c33 |
405 | |
406 | pr->s = s = sk_register(sock, (Plug) pr); |
808c3834 |
407 | if ((err = sk_socket_error(s)) != NULL) { |
f26d5c33 |
408 | sfree(pr); |
409 | return err != NULL; |
410 | } |
411 | |
820ebe3b |
412 | sk_set_private_ptr(s, pr); |
f26d5c33 |
413 | |
5471d09a |
414 | pr->throttled = pr->throttle_override = 0; |
f26d5c33 |
415 | pr->ready = 0; |
f26d5c33 |
416 | |
820ebe3b |
417 | if (org->dynamic) { |
418 | pr->dynamic = 1; |
b8a98e25 |
419 | pr->port = 0; /* "hostname" buffer is so far empty */ |
820ebe3b |
420 | sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */ |
f26d5c33 |
421 | } else { |
4b42e4f6 |
422 | pr->dynamic = 0; |
820ebe3b |
423 | strcpy(pr->hostname, org->hostname); |
424 | pr->port = org->port; |
425 | pr->c = new_sock_channel(org->backhandle, s); |
426 | |
427 | if (pr->c == NULL) { |
428 | sfree(pr); |
429 | return 1; |
430 | } else { |
431 | /* asks to forward to the specified host/port for this */ |
432 | ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding"); |
433 | } |
f26d5c33 |
434 | } |
435 | |
436 | return 0; |
437 | } |
438 | |
439 | |
440 | /* Add a new forwarding from port -> desthost:destport |
6ee9b735 |
441 | sets up a listener on the local machine on (srcaddr:)port |
f26d5c33 |
442 | */ |
cbe2d68f |
443 | const char *pfd_addforward(char *desthost, int destport, char *srcaddr, |
4a693cfc |
444 | int port, void *backhandle, Conf *conf, |
05581745 |
445 | void **sockdata, int address_family) |
f26d5c33 |
446 | { |
c85623f9 |
447 | static const struct plug_function_table fn_table = { |
7555d6a5 |
448 | pfd_log, |
f26d5c33 |
449 | pfd_closing, |
5471d09a |
450 | pfd_receive, /* should not happen... */ |
451 | pfd_sent, /* also should not happen */ |
f26d5c33 |
452 | pfd_accepting |
453 | }; |
454 | |
cbe2d68f |
455 | const char *err; |
f26d5c33 |
456 | struct PFwdPrivate *pr; |
457 | Socket s; |
458 | |
459 | /* |
460 | * Open socket. |
461 | */ |
3d88e64d |
462 | pr = snew(struct PFwdPrivate); |
820ebe3b |
463 | pr->buffer = NULL; |
f26d5c33 |
464 | pr->fn = &fn_table; |
465 | pr->c = NULL; |
820ebe3b |
466 | if (desthost) { |
467 | strcpy(pr->hostname, desthost); |
468 | pr->port = destport; |
469 | pr->dynamic = 0; |
470 | } else |
471 | pr->dynamic = 1; |
5471d09a |
472 | pr->throttled = pr->throttle_override = 0; |
f26d5c33 |
473 | pr->ready = 0; |
6b78788a |
474 | pr->backhandle = backhandle; |
f26d5c33 |
475 | |
e8fa8f62 |
476 | pr->s = s = new_listener(srcaddr, port, (Plug) pr, |
4a693cfc |
477 | !conf_get_int(conf, CONF_lport_acceptall), |
478 | conf, address_family); |
808c3834 |
479 | if ((err = sk_socket_error(s)) != NULL) { |
f26d5c33 |
480 | sfree(pr); |
481 | return err; |
482 | } |
483 | |
484 | sk_set_private_ptr(s, pr); |
485 | |
fda2feb1 |
486 | *sockdata = (void *)s; |
487 | |
f26d5c33 |
488 | return NULL; |
489 | } |
490 | |
491 | void pfd_close(Socket s) |
492 | { |
493 | struct PFwdPrivate *pr; |
494 | |
495 | if (!s) |
496 | return; |
497 | |
498 | pr = (struct PFwdPrivate *) sk_get_private_ptr(s); |
499 | |
820ebe3b |
500 | sfree(pr->buffer); |
f26d5c33 |
501 | sfree(pr); |
502 | |
503 | sk_close(s); |
504 | } |
505 | |
fda2feb1 |
506 | /* |
507 | * Terminate a listener. |
508 | */ |
509 | void pfd_terminate(void *sv) |
510 | { |
511 | pfd_close((Socket)sv); |
512 | } |
513 | |
5471d09a |
514 | void pfd_unthrottle(Socket s) |
515 | { |
516 | struct PFwdPrivate *pr; |
517 | if (!s) |
518 | return; |
519 | pr = (struct PFwdPrivate *) sk_get_private_ptr(s); |
520 | |
521 | pr->throttled = 0; |
522 | sk_set_frozen(s, pr->throttled || pr->throttle_override); |
523 | } |
524 | |
525 | void pfd_override_throttle(Socket s, int enable) |
526 | { |
527 | struct PFwdPrivate *pr; |
528 | if (!s) |
529 | return; |
530 | pr = (struct PFwdPrivate *) sk_get_private_ptr(s); |
531 | |
532 | pr->throttle_override = enable; |
533 | sk_set_frozen(s, pr->throttled || pr->throttle_override); |
534 | } |
535 | |
f26d5c33 |
536 | /* |
537 | * Called to send data down the raw connection. |
538 | */ |
5471d09a |
539 | int pfd_send(Socket s, char *data, int len) |
f26d5c33 |
540 | { |
f26d5c33 |
541 | if (s == NULL) |
5471d09a |
542 | return 0; |
543 | return sk_write(s, data, len); |
f26d5c33 |
544 | } |
545 | |
bc06669b |
546 | void pfd_send_eof(Socket s) |
547 | { |
548 | sk_write_eof(s); |
549 | } |
f26d5c33 |
550 | |
551 | void pfd_confirm(Socket s) |
552 | { |
5f2e19fc |
553 | struct PFwdPrivate *pr; |
f26d5c33 |
554 | |
555 | if (s == NULL) |
556 | return; |
557 | |
5f2e19fc |
558 | pr = (struct PFwdPrivate *) sk_get_private_ptr(s); |
f26d5c33 |
559 | pr->ready = 1; |
560 | sk_set_frozen(s, 0); |
561 | sk_write(s, NULL, 0); |
820ebe3b |
562 | if (pr->buffer) { |
563 | sshfwd_write(pr->c, pr->buffer, pr->buflen); |
564 | sfree(pr->buffer); |
565 | pr->buffer = NULL; |
566 | } |
f26d5c33 |
567 | } |