Integrate unfix.org's IPv6 patches up to level 10, with rather a lot
[u/mdw/putty] / portfwd.c
1 #include <stdio.h>
2 #include <stdlib.h>
3
4 #include "putty.h"
5 #include "ssh.h"
6
7 #ifndef FALSE
8 #define FALSE 0
9 #endif
10 #ifndef TRUE
11 #define TRUE 1
12 #endif
13
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))
19
20 #define PUT_32BIT_LSB_FIRST(cp, value) ( \
21 (cp)[0] = (value), \
22 (cp)[1] = (value) >> 8, \
23 (cp)[2] = (value) >> 16, \
24 (cp)[3] = (value) >> 24 )
25
26 #define GET_16BIT_LSB_FIRST(cp) \
27 (((unsigned long)(unsigned char)(cp)[0]) | \
28 ((unsigned long)(unsigned char)(cp)[1] << 8))
29
30 #define PUT_16BIT_LSB_FIRST(cp, value) ( \
31 (cp)[0] = (value), \
32 (cp)[1] = (value) >> 8 )
33
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]))
39
40 #define PUT_32BIT_MSB_FIRST(cp, value) ( \
41 (cp)[0] = (value) >> 24, \
42 (cp)[1] = (value) >> 16, \
43 (cp)[2] = (value) >> 8, \
44 (cp)[3] = (value) )
45
46 #define GET_16BIT_MSB_FIRST(cp) \
47 (((unsigned long)(unsigned char)(cp)[0] << 8) | \
48 ((unsigned long)(unsigned char)(cp)[1]))
49
50 #define PUT_16BIT_MSB_FIRST(cp, value) ( \
51 (cp)[0] = (value) >> 8, \
52 (cp)[1] = (value) )
53
54 struct PFwdPrivate {
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 */
60 Socket s;
61 int throttled, throttle_override;
62 int ready;
63 /*
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
67 * exchange.
68 */
69 int dynamic;
70 /*
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.
76 */
77 char hostname[256+8];
78 int port;
79 /*
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.
84 */
85 void *buffer;
86 int buflen;
87 };
88
89 static int pfd_closing(Plug plug, const char *error_msg, int error_code,
90 int calling_back)
91 {
92 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
93
94 /*
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.
98 */
99 if (pr->c)
100 sshfwd_close(pr->c);
101 pfd_close(pr->s);
102 return 1;
103 }
104
105 static int pfd_receive(Plug plug, int urgent, char *data, int len)
106 {
107 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
108 if (pr->dynamic) {
109 while (len--) {
110 /*
111 * Throughout SOCKS negotiation, "hostname" is re-used as a
112 * random protocol buffer with "port" storing the length.
113 */
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. */
118 char data[8];
119 memset(data, 0, sizeof(data));
120 data[1] = 91; /* generic `request rejected' */
121 sk_write(pr->s, data, 8);
122 }
123 pfd_close(pr->s);
124 return 1;
125 }
126 pr->hostname[pr->port++] = *data++;
127
128 /*
129 * Now check what's in the buffer to see if it's a
130 * valid and complete message in the SOCKS exchange.
131 */
132 if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) &&
133 pr->hostname[0] == 4) {
134 /*
135 * SOCKS 4.
136 */
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) {
141 /* Not CONNECT. */
142 /* Send back a SOCKS 4 error before closing. */
143 char data[8];
144 memset(data, 0, sizeof(data));
145 data[1] = 91; /* generic `request rejected' */
146 sk_write(pr->s, data, 8);
147 pfd_close(pr->s);
148 return 1;
149 }
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 */
153 /*
154 * Now we have a full SOCKS 4 request. Check it to
155 * see if it's a SOCKS 4A request.
156 */
157 if (pr->hostname[4] == 0 && pr->hostname[5] == 0 &&
158 pr->hostname[6] == 0 && pr->hostname[7] != 0) {
159 /*
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.
164 */
165 int len;
166 if (pr->dynamic == 0x4000) {
167 pr->dynamic = 0x4001;
168 pr->port = 8; /* reset buffer to overwrite name */
169 continue;
170 }
171 pr->hostname[0] = 0; /* reply version code */
172 pr->hostname[1] = 90; /* request granted */
173 sk_write(pr->s, pr->hostname, 8);
174 len= pr->port - 8;
175 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
176 memmove(pr->hostname, pr->hostname + 8, len);
177 goto connect;
178 } else {
179 /*
180 * It's SOCKS 4, which means we should format
181 * the IP address into the hostname string and
182 * then just go.
183 */
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]);
193 goto connect;
194 }
195 }
196
197 if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) &&
198 pr->hostname[0] == 5) {
199 /*
200 * SOCKS 5.
201 */
202 if (pr->dynamic == 1)
203 pr->dynamic = 0x5000;
204
205 if (pr->dynamic == 0x5000) {
206 int i, method;
207 char data[2];
208 /*
209 * We're receiving a set of method identifiers.
210 */
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 */
218 break;
219 }
220 data[0] = 5;
221 data[1] = method;
222 sk_write(pr->s, data, 2);
223 pr->dynamic = 0x5001;
224 pr->port = 0; /* re-empty the buffer */
225 continue;
226 }
227
228 if (pr->dynamic == 0x5001) {
229 /*
230 * We're receiving a SOCKS request.
231 */
232 unsigned char reply[10]; /* SOCKS5 atyp=1 reply */
233 int atype, alen = 0;
234
235 /*
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
240 * ignored.
241 */
242 memset(reply, 0, lenof(reply));
243 reply[0] = 5; /* VER */
244 reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */
245
246 if (pr->port < 6) continue;
247 atype = (unsigned char)pr->hostname[3];
248 if (atype == 1) /* IPv4 address */
249 alen = 4;
250 if (atype == 4) /* IPv6 address */
251 alen = 16;
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));
259 pfd_close(pr->s);
260 return 1;
261 }
262 /*
263 * Now we have a viable connect request. Switch
264 * on atype.
265 */
266 pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen);
267 if (atype == 1) {
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]);
275 goto connect;
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';
281 goto connect;
282 } else {
283 /*
284 * Unknown address type. (FIXME: support IPv6!)
285 */
286 reply[1] = 8; /* atype not supported */
287 sk_write(pr->s, (char *) reply, lenof(reply));
288 pfd_close(pr->s);
289 return 1;
290 }
291 }
292 }
293
294 /*
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.
299 */
300 pfd_close(pr->s);
301 return 1;
302 }
303 return 1;
304
305 /*
306 * We come here when we're ready to make an actual
307 * connection.
308 */
309 connect:
310
311 pr->c = new_sock_channel(pr->backhandle, pr->s);
312 if (pr->c == NULL) {
313 pfd_close(pr->s);
314 return 1;
315 } else {
316 /* asks to forward to the specified host/port for this */
317 ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
318 }
319 pr->dynamic = 0;
320
321 /*
322 * Now freeze the socket until the SSH server confirms the
323 * connection.
324 */
325 sk_set_frozen(pr->s, 1);
326 /*
327 * If there's any data remaining in our current buffer,
328 * save it to be sent on pfd_confirm().
329 */
330 if (len > 0) {
331 pr->buffer = snewn(len, char);
332 memcpy(pr->buffer, data, len);
333 pr->buflen = len;
334 }
335 }
336 if (pr->ready) {
337 if (sshfwd_write(pr->c, data, len) > 0) {
338 pr->throttled = 1;
339 sk_set_frozen(pr->s, 1);
340 }
341 }
342 return 1;
343 }
344
345 static void pfd_sent(Plug plug, int bufsize)
346 {
347 struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
348
349 if (pr->c)
350 sshfwd_unthrottle(pr->c, bufsize);
351 }
352
353 /*
354 * Called when receiving a PORT OPEN from the server
355 */
356 const char *pfd_newconnect(Socket *s, char *hostname, int port,
357 void *c, const Config *cfg, int addressfamily)
358 {
359 static const struct plug_function_table fn_table = {
360 pfd_closing,
361 pfd_receive,
362 pfd_sent,
363 NULL
364 };
365
366 SockAddr addr;
367 const char *err;
368 char *dummy_realhost;
369 struct PFwdPrivate *pr;
370
371 /*
372 * Try to find host.
373 */
374 addr = name_lookup(hostname, port, &dummy_realhost, cfg, addressfamily);
375 if ((err = sk_addr_error(addr)) != NULL) {
376 sk_addr_free(addr);
377 return err;
378 }
379
380 /*
381 * Open socket.
382 */
383 pr = snew(struct PFwdPrivate);
384 pr->buffer = NULL;
385 pr->fn = &fn_table;
386 pr->throttled = pr->throttle_override = 0;
387 pr->ready = 1;
388 pr->c = c;
389 pr->backhandle = NULL; /* we shouldn't need this */
390 pr->dynamic = 0;
391
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) {
395 sfree(pr);
396 return err;
397 }
398
399 sk_set_private_ptr(*s, pr);
400 return NULL;
401 }
402
403 /*
404 called when someone connects to the local port
405 */
406
407 static int pfd_accepting(Plug p, OSSocket sock)
408 {
409 static const struct plug_function_table fn_table = {
410 pfd_closing,
411 pfd_receive,
412 pfd_sent,
413 NULL
414 };
415 struct PFwdPrivate *pr, *org;
416 Socket s;
417 const char *err;
418
419 org = (struct PFwdPrivate *)p;
420 pr = snew(struct PFwdPrivate);
421 pr->buffer = NULL;
422 pr->fn = &fn_table;
423
424 pr->c = NULL;
425 pr->backhandle = org->backhandle;
426
427 pr->s = s = sk_register(sock, (Plug) pr);
428 if ((err = sk_socket_error(s)) != NULL) {
429 sfree(pr);
430 return err != NULL;
431 }
432
433 sk_set_private_ptr(s, pr);
434
435 pr->throttled = pr->throttle_override = 0;
436 pr->ready = 0;
437
438 if (org->dynamic) {
439 pr->dynamic = 1;
440 pr->port = 0; /* "hostname" buffer is so far empty */
441 sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */
442 } else {
443 pr->dynamic = 0;
444 strcpy(pr->hostname, org->hostname);
445 pr->port = org->port;
446 pr->c = new_sock_channel(org->backhandle, s);
447
448 if (pr->c == NULL) {
449 sfree(pr);
450 return 1;
451 } else {
452 /* asks to forward to the specified host/port for this */
453 ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
454 }
455 }
456
457 return 0;
458 }
459
460
461 /* Add a new forwarding from port -> desthost:destport
462 sets up a listener on the local machine on (srcaddr:)port
463 */
464 const char *pfd_addforward(char *desthost, int destport, char *srcaddr,
465 int port, void *backhandle, const Config *cfg,
466 void **sockdata, int address_family)
467 {
468 static const struct plug_function_table fn_table = {
469 pfd_closing,
470 pfd_receive, /* should not happen... */
471 pfd_sent, /* also should not happen */
472 pfd_accepting
473 };
474
475 const char *err;
476 struct PFwdPrivate *pr;
477 Socket s;
478
479 /*
480 * Open socket.
481 */
482 pr = snew(struct PFwdPrivate);
483 pr->buffer = NULL;
484 pr->fn = &fn_table;
485 pr->c = NULL;
486 if (desthost) {
487 strcpy(pr->hostname, desthost);
488 pr->port = destport;
489 pr->dynamic = 0;
490 } else
491 pr->dynamic = 1;
492 pr->throttled = pr->throttle_override = 0;
493 pr->ready = 0;
494 pr->backhandle = backhandle;
495
496 pr->s = s = new_listener(srcaddr, port, (Plug) pr,
497 !cfg->lport_acceptall, cfg, address_family);
498 if ((err = sk_socket_error(s)) != NULL) {
499 sfree(pr);
500 return err;
501 }
502
503 sk_set_private_ptr(s, pr);
504
505 *sockdata = (void *)s;
506
507 return NULL;
508 }
509
510 void pfd_close(Socket s)
511 {
512 struct PFwdPrivate *pr;
513
514 if (!s)
515 return;
516
517 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
518
519 sfree(pr->buffer);
520 sfree(pr);
521
522 sk_close(s);
523 }
524
525 /*
526 * Terminate a listener.
527 */
528 void pfd_terminate(void *sv)
529 {
530 pfd_close((Socket)sv);
531 }
532
533 void pfd_unthrottle(Socket s)
534 {
535 struct PFwdPrivate *pr;
536 if (!s)
537 return;
538 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
539
540 pr->throttled = 0;
541 sk_set_frozen(s, pr->throttled || pr->throttle_override);
542 }
543
544 void pfd_override_throttle(Socket s, int enable)
545 {
546 struct PFwdPrivate *pr;
547 if (!s)
548 return;
549 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
550
551 pr->throttle_override = enable;
552 sk_set_frozen(s, pr->throttled || pr->throttle_override);
553 }
554
555 /*
556 * Called to send data down the raw connection.
557 */
558 int pfd_send(Socket s, char *data, int len)
559 {
560 if (s == NULL)
561 return 0;
562 return sk_write(s, data, len);
563 }
564
565
566 void pfd_confirm(Socket s)
567 {
568 struct PFwdPrivate *pr;
569
570 if (s == NULL)
571 return;
572
573 pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
574 pr->ready = 1;
575 sk_set_frozen(s, 0);
576 sk_write(s, NULL, 0);
577 if (pr->buffer) {
578 sshfwd_write(pr->c, pr->buffer, pr->buflen);
579 sfree(pr->buffer);
580 pr->buffer = NULL;
581 }
582 }