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Commit | Line | Data |
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1c1af145 | 1 | /* |
2 | * SSH port forwarding. | |
3 | */ | |
4 | ||
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 | ||
18 | struct PFwdPrivate { | |
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 */ | |
24 | Socket s; | |
25 | int throttled, throttle_override; | |
26 | int ready; | |
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 | */ | |
41 | char hostname[256+8]; | |
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; | |
51 | }; | |
52 | ||
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 | ||
59 | static int pfd_closing(Plug plug, const char *error_msg, int error_code, | |
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 | */ | |
69 | if (pr->c) | |
70 | sshfwd_close(pr->c); | |
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; | |
78 | if (pr->dynamic) { | |
79 | while (len--) { | |
80 | /* | |
81 | * Throughout SOCKS negotiation, "hostname" is re-used as a | |
82 | * random protocol buffer with "port" storing the length. | |
83 | */ | |
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. */ | |
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) { | |
111 | /* Not CONNECT. */ | |
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 | } | |
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 */ | |
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; | |
138 | pr->port = 8; /* reset buffer to overwrite name */ | |
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); | |
144 | len= pr->port - 8; | |
145 | pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2); | |
146 | memmove(pr->hostname, pr->hostname + 8, len); | |
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) { | |
199 | /* | |
200 | * We're receiving a SOCKS request. | |
201 | */ | |
202 | unsigned char reply[10]; /* SOCKS5 atyp=1 reply */ | |
203 | int atype, alen = 0; | |
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 | ||
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) { | |
226 | /* Not CONNECT or reserved field nonzero - error */ | |
227 | reply[1] = 1; /* generic failure */ | |
228 | sk_write(pr->s, (char *) reply, lenof(reply)); | |
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) { | |
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]); | |
245 | goto connect; | |
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'; | |
251 | goto connect; | |
252 | } else { | |
253 | /* | |
254 | * Unknown address type. (FIXME: support IPv6!) | |
255 | */ | |
256 | reply[1] = 8; /* atype not supported */ | |
257 | sk_write(pr->s, (char *) reply, lenof(reply)); | |
258 | pfd_close(pr->s); | |
259 | return 1; | |
260 | } | |
261 | } | |
262 | } | |
263 | ||
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 | ||
281 | /* | |
282 | * Freeze the socket until the SSH server confirms the | |
283 | * connection. | |
284 | */ | |
285 | sk_set_frozen(pr->s, 1); | |
286 | ||
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 | /* | |
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 | } | |
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 | } | |
313 | return 1; | |
314 | } | |
315 | ||
316 | static void pfd_sent(Plug plug, int bufsize) | |
317 | { | |
318 | struct PFwdPrivate *pr = (struct PFwdPrivate *) plug; | |
319 | ||
320 | if (pr->c) | |
321 | sshfwd_unthrottle(pr->c, bufsize); | |
322 | } | |
323 | ||
324 | /* | |
325 | * Called when receiving a PORT OPEN from the server | |
326 | */ | |
327 | const char *pfd_newconnect(Socket *s, char *hostname, int port, | |
328 | void *c, const Config *cfg, int addressfamily) | |
329 | { | |
330 | static const struct plug_function_table fn_table = { | |
331 | pfd_log, | |
332 | pfd_closing, | |
333 | pfd_receive, | |
334 | pfd_sent, | |
335 | NULL | |
336 | }; | |
337 | ||
338 | SockAddr addr; | |
339 | const char *err; | |
340 | char *dummy_realhost; | |
341 | struct PFwdPrivate *pr; | |
342 | ||
343 | /* | |
344 | * Try to find host. | |
345 | */ | |
346 | addr = name_lookup(hostname, port, &dummy_realhost, cfg, addressfamily); | |
347 | if ((err = sk_addr_error(addr)) != NULL) { | |
348 | sk_addr_free(addr); | |
349 | return err; | |
350 | } | |
351 | ||
352 | /* | |
353 | * Open socket. | |
354 | */ | |
355 | pr = snew(struct PFwdPrivate); | |
356 | pr->buffer = NULL; | |
357 | pr->fn = &fn_table; | |
358 | pr->throttled = pr->throttle_override = 0; | |
359 | pr->ready = 1; | |
360 | pr->c = c; | |
361 | pr->backhandle = NULL; /* we shouldn't need this */ | |
362 | pr->dynamic = 0; | |
363 | ||
364 | pr->s = *s = new_connection(addr, dummy_realhost, port, | |
365 | 0, 1, 0, 0, (Plug) pr, cfg); | |
366 | if ((err = sk_socket_error(*s)) != NULL) { | |
367 | sfree(pr); | |
368 | return err; | |
369 | } | |
370 | ||
371 | sk_set_private_ptr(*s, pr); | |
372 | return NULL; | |
373 | } | |
374 | ||
375 | /* | |
376 | called when someone connects to the local port | |
377 | */ | |
378 | ||
379 | static int pfd_accepting(Plug p, OSSocket sock) | |
380 | { | |
381 | static const struct plug_function_table fn_table = { | |
382 | pfd_log, | |
383 | pfd_closing, | |
384 | pfd_receive, | |
385 | pfd_sent, | |
386 | NULL | |
387 | }; | |
388 | struct PFwdPrivate *pr, *org; | |
389 | Socket s; | |
390 | const char *err; | |
391 | ||
392 | org = (struct PFwdPrivate *)p; | |
393 | pr = snew(struct PFwdPrivate); | |
394 | pr->buffer = NULL; | |
395 | pr->fn = &fn_table; | |
396 | ||
397 | pr->c = NULL; | |
398 | pr->backhandle = org->backhandle; | |
399 | ||
400 | pr->s = s = sk_register(sock, (Plug) pr); | |
401 | if ((err = sk_socket_error(s)) != NULL) { | |
402 | sfree(pr); | |
403 | return err != NULL; | |
404 | } | |
405 | ||
406 | sk_set_private_ptr(s, pr); | |
407 | ||
408 | pr->throttled = pr->throttle_override = 0; | |
409 | pr->ready = 0; | |
410 | ||
411 | if (org->dynamic) { | |
412 | pr->dynamic = 1; | |
413 | pr->port = 0; /* "hostname" buffer is so far empty */ | |
414 | sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */ | |
415 | } else { | |
416 | pr->dynamic = 0; | |
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 | } | |
428 | } | |
429 | ||
430 | return 0; | |
431 | } | |
432 | ||
433 | ||
434 | /* Add a new forwarding from port -> desthost:destport | |
435 | sets up a listener on the local machine on (srcaddr:)port | |
436 | */ | |
437 | const char *pfd_addforward(char *desthost, int destport, char *srcaddr, | |
438 | int port, void *backhandle, const Config *cfg, | |
439 | void **sockdata, int address_family) | |
440 | { | |
441 | static const struct plug_function_table fn_table = { | |
442 | pfd_log, | |
443 | pfd_closing, | |
444 | pfd_receive, /* should not happen... */ | |
445 | pfd_sent, /* also should not happen */ | |
446 | pfd_accepting | |
447 | }; | |
448 | ||
449 | const char *err; | |
450 | struct PFwdPrivate *pr; | |
451 | Socket s; | |
452 | ||
453 | /* | |
454 | * Open socket. | |
455 | */ | |
456 | pr = snew(struct PFwdPrivate); | |
457 | pr->buffer = NULL; | |
458 | pr->fn = &fn_table; | |
459 | pr->c = NULL; | |
460 | if (desthost) { | |
461 | strcpy(pr->hostname, desthost); | |
462 | pr->port = destport; | |
463 | pr->dynamic = 0; | |
464 | } else | |
465 | pr->dynamic = 1; | |
466 | pr->throttled = pr->throttle_override = 0; | |
467 | pr->ready = 0; | |
468 | pr->backhandle = backhandle; | |
469 | ||
470 | pr->s = s = new_listener(srcaddr, port, (Plug) pr, | |
471 | !cfg->lport_acceptall, cfg, address_family); | |
472 | if ((err = sk_socket_error(s)) != NULL) { | |
473 | sfree(pr); | |
474 | return err; | |
475 | } | |
476 | ||
477 | sk_set_private_ptr(s, pr); | |
478 | ||
479 | *sockdata = (void *)s; | |
480 | ||
481 | return NULL; | |
482 | } | |
483 | ||
484 | void pfd_close(Socket s) | |
485 | { | |
486 | struct PFwdPrivate *pr; | |
487 | ||
488 | if (!s) | |
489 | return; | |
490 | ||
491 | pr = (struct PFwdPrivate *) sk_get_private_ptr(s); | |
492 | ||
493 | sfree(pr->buffer); | |
494 | sfree(pr); | |
495 | ||
496 | sk_close(s); | |
497 | } | |
498 | ||
499 | /* | |
500 | * Terminate a listener. | |
501 | */ | |
502 | void pfd_terminate(void *sv) | |
503 | { | |
504 | pfd_close((Socket)sv); | |
505 | } | |
506 | ||
507 | void pfd_unthrottle(Socket s) | |
508 | { | |
509 | struct PFwdPrivate *pr; | |
510 | if (!s) | |
511 | return; | |
512 | pr = (struct PFwdPrivate *) sk_get_private_ptr(s); | |
513 | ||
514 | pr->throttled = 0; | |
515 | sk_set_frozen(s, pr->throttled || pr->throttle_override); | |
516 | } | |
517 | ||
518 | void pfd_override_throttle(Socket s, int enable) | |
519 | { | |
520 | struct PFwdPrivate *pr; | |
521 | if (!s) | |
522 | return; | |
523 | pr = (struct PFwdPrivate *) sk_get_private_ptr(s); | |
524 | ||
525 | pr->throttle_override = enable; | |
526 | sk_set_frozen(s, pr->throttled || pr->throttle_override); | |
527 | } | |
528 | ||
529 | /* | |
530 | * Called to send data down the raw connection. | |
531 | */ | |
532 | int pfd_send(Socket s, char *data, int len) | |
533 | { | |
534 | if (s == NULL) | |
535 | return 0; | |
536 | return sk_write(s, data, len); | |
537 | } | |
538 | ||
539 | ||
540 | void pfd_confirm(Socket s) | |
541 | { | |
542 | struct PFwdPrivate *pr; | |
543 | ||
544 | if (s == NULL) | |
545 | return; | |
546 | ||
547 | pr = (struct PFwdPrivate *) sk_get_private_ptr(s); | |
548 | pr->ready = 1; | |
549 | sk_set_frozen(s, 0); | |
550 | sk_write(s, NULL, 0); | |
551 | if (pr->buffer) { | |
552 | sshfwd_write(pr->c, pr->buffer, pr->buflen); | |
553 | sfree(pr->buffer); | |
554 | pr->buffer = NULL; | |
555 | } | |
556 | } |