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set length properly
[l2tpns.git] / ppp.c
1 // L2TPNS PPP Stuff
2
3 char const *cvs_id_ppp = "$Id: ppp.c,v 1.56 2005/05/10 09:47:23 bodea Exp $";
4
5 #include <stdio.h>
6 #include <string.h>
7 #include <unistd.h>
8 #include <errno.h>
9 #include <stdlib.h>
10 #include "l2tpns.h"
11 #include "constants.h"
12 #include "plugin.h"
13 #include "util.h"
14 #include "tbf.h"
15 #include "cluster.h"
16
17 extern tunnelt *tunnel;
18 extern sessiont *session;
19 extern radiust *radius;
20 extern int tunfd;
21 extern char hostname[];
22 extern uint32_t eth_tx;
23 extern time_t time_now;
24 extern configt *config;
25
26 static void initccp(tunnelidt t, sessionidt s);
27 static uint8_t *add_lcp_auth(uint8_t *b, int size, int authtype);
28
29 // Process PAP messages
30 void processpap(tunnelidt t, sessionidt s, uint8_t *p, uint16_t l)
31 {
32 char user[MAXUSER];
33 char pass[MAXPASS];
34 uint16_t hl;
35
36 CSTAT(processpap);
37
38 LOG_HEX(5, "PAP", p, l);
39 if (l < 4)
40 {
41 LOG(1, s, t, "Short PAP %u bytes\n", l);
42 STAT(tunnel_rx_errors);
43 sessionshutdown(s, "Short PAP packet.", 3, 0);
44 return;
45 }
46
47 if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
48 {
49 LOG(1, s, t, "Length mismatch PAP %u/%u\n", hl, l);
50 STAT(tunnel_rx_errors);
51 sessionshutdown(s, "PAP length mismatch.", 3, 0);
52 return;
53 }
54 l = hl;
55
56 if (*p != 1)
57 {
58 LOG(1, s, t, "Unexpected PAP code %d\n", *p);
59 STAT(tunnel_rx_errors);
60 sessionshutdown(s, "Unexpected PAP code.", 3, 0);
61 return;
62 }
63
64 {
65 uint8_t *b = p;
66 b += 4;
67 user[0] = pass[0] = 0;
68 if (*b && *b < sizeof(user))
69 {
70 memcpy(user, b + 1, *b);
71 user[*b] = 0;
72 b += 1 + *b;
73 if (*b && *b < sizeof(pass))
74 {
75 memcpy(pass, b + 1, *b);
76 pass[*b] = 0;
77 }
78 }
79 LOG(3, s, t, "PAP login %s/%s\n", user, pass);
80 }
81 if (session[s].ip || !sess_local[s].radius)
82 {
83 // respond now, either no RADIUS available or already authenticated
84 uint8_t b[MAXCONTROL];
85 uint8_t id = p[1];
86 uint8_t *p = makeppp(b, sizeof(b), 0, 0, t, s, PPPPAP);
87 if (!p) return;
88
89 if (session[s].ip)
90 *p = 2; // ACK
91 else
92 *p = 3; // cant authorise
93 p[1] = id;
94 *(uint16_t *) (p + 2) = htons(5); // length
95 p[4] = 0; // no message
96 if (session[s].ip)
97 {
98 LOG(3, s, t, "Already an IP allocated: %s (%d)\n",
99 fmtaddr(htonl(session[s].ip), 0), session[s].ip_pool_index);
100
101 session[s].flags &= ~SF_IPCP_ACKED;
102 }
103 else
104 {
105 LOG(1, s, t, "No radius session available to authenticate session...\n");
106 }
107 LOG(3, s, t, "Fallback response to PAP (%s)\n", (session[s].ip) ? "ACK" : "NAK");
108 tunnelsend(b, 5 + (p - b), t); // send it
109 sessionshutdown(s, "PAP authentication failed.", 3, 0);
110 }
111 else
112 {
113 // set up RADIUS request
114 uint16_t r = sess_local[s].radius;
115
116 // Run PRE_AUTH plugins
117 struct param_pre_auth packet = { &tunnel[t], &session[s], strdup(user), strdup(pass), PPPPAP, 1 };
118 run_plugins(PLUGIN_PRE_AUTH, &packet);
119 if (!packet.continue_auth)
120 {
121 LOG(3, s, t, "A plugin rejected PRE_AUTH\n");
122 if (packet.username) free(packet.username);
123 if (packet.password) free(packet.password);
124 return;
125 }
126
127 strncpy(session[s].user, packet.username, sizeof(session[s].user) - 1);
128 strncpy(radius[r].pass, packet.password, sizeof(radius[r].pass) - 1);
129
130 free(packet.username);
131 free(packet.password);
132
133 radius[r].id = p[1];
134 LOG(3, s, t, "Sending login for %s/%s to radius\n", user, pass);
135 radiussend(r, RADIUSAUTH);
136 }
137 }
138
139 // Process CHAP messages
140 void processchap(tunnelidt t, sessionidt s, uint8_t *p, uint16_t l)
141 {
142 uint16_t r;
143 uint16_t hl;
144
145 CSTAT(processchap);
146
147 LOG_HEX(5, "CHAP", p, l);
148 r = sess_local[s].radius;
149 if (!r)
150 {
151 LOG(1, s, t, "Unexpected CHAP message\n");
152 STAT(tunnel_rx_errors);
153 sessionshutdown(s, "Unexpected CHAP message.", 3, 0);
154 return;
155 }
156
157 if (l < 4)
158 {
159 LOG(1, s, t, "Short CHAP %u bytes\n", l);
160 STAT(tunnel_rx_errors);
161 sessionshutdown(s, "Short CHAP packet.", 3, 0);
162 return;
163 }
164
165 if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
166 {
167 LOG(1, s, t, "Length mismatch CHAP %u/%u\n", hl, l);
168 STAT(tunnel_rx_errors);
169 sessionshutdown(s, "CHAP length mismatch.", 3, 0);
170 return;
171 }
172 l = hl;
173
174 if (*p != 2)
175 {
176 LOG(1, s, t, "Unexpected CHAP response code %d\n", *p);
177 STAT(tunnel_rx_errors);
178 sessionshutdown(s, "CHAP length mismatch.", 3, 0);
179 return;
180 }
181 if (p[1] != radius[r].id)
182 {
183 LOG(1, s, t, "Wrong CHAP response ID %d (should be %d) (%d)\n", p[1], radius[r].id, r);
184 STAT(tunnel_rx_errors);
185 sessionshutdown(s, "Unexpected CHAP response ID.", 3, 0);
186 return;
187 }
188
189 if (l < 5 || p[4] != 16)
190 {
191 LOG(1, s, t, "Bad CHAP response length %d\n", l < 5 ? -1 : p[4]);
192 STAT(tunnel_rx_errors);
193 sessionshutdown(s, "Bad CHAP response length.", 3, 0);
194 return;
195 }
196
197 l -= 5;
198 p += 5;
199 if (l < 16 || l - 16 >= sizeof(session[s].user))
200 {
201 LOG(1, s, t, "CHAP user too long %d\n", l - 16);
202 STAT(tunnel_rx_errors);
203 sessionshutdown(s, "CHAP username too long.", 3, 0);
204 return;
205 }
206
207 // Run PRE_AUTH plugins
208 {
209 struct param_pre_auth packet = { &tunnel[t], &session[s], NULL, NULL, PPPCHAP, 1 };
210
211 packet.password = calloc(17, 1);
212 memcpy(packet.password, p, 16);
213
214 p += 16;
215 l -= 16;
216
217 packet.username = calloc(l + 1, 1);
218 memcpy(packet.username, p, l);
219
220 run_plugins(PLUGIN_PRE_AUTH, &packet);
221 if (!packet.continue_auth)
222 {
223 LOG(3, s, t, "A plugin rejected PRE_AUTH\n");
224 if (packet.username) free(packet.username);
225 if (packet.password) free(packet.password);
226 return;
227 }
228
229 strncpy(session[s].user, packet.username, sizeof(session[s].user) - 1);
230 memcpy(radius[r].pass, packet.password, 16);
231
232 free(packet.username);
233 free(packet.password);
234 }
235
236 radius[r].chap = 1;
237 LOG(3, s, t, "CHAP login %s\n", session[s].user);
238 radiussend(r, RADIUSAUTH);
239 }
240
241 static void dumplcp(uint8_t *p, int l)
242 {
243 int x = l - 4;
244 uint8_t *o = (p + 4);
245
246 LOG_HEX(5, "PPP LCP Packet", p, l);
247 LOG(4, 0, 0, "PPP LCP Packet type %d (%s len %d)\n", *p, ppp_lcp_type((int)*p), ntohs( ((uint16_t *) p)[1]) );
248 LOG(4, 0, 0, "Length: %d\n", l);
249 if (*p != ConfigReq && *p != ConfigRej && *p != ConfigAck)
250 return;
251
252 while (x > 2)
253 {
254 int type = o[0];
255 int length = o[1];
256 if (length < 2)
257 {
258 LOG(4, 0, 0, " Option length is %d...\n", length);
259 break;
260 }
261 if (type == 0)
262 {
263 LOG(4, 0, 0, " Option type is 0...\n");
264 x -= length;
265 o += length;
266 continue;
267 }
268 switch (type)
269 {
270 case 1: // Maximum-Receive-Unit
271 if (length == 4)
272 LOG(4, 0, 0, " %s %d\n", lcp_type(type), ntohs(*(uint16_t *)(o + 2)));
273 else
274 LOG(4, 0, 0, " %s odd length %d\n", lcp_type(type), length);
275 break;
276 case 2: // Async-Control-Character-Map
277 if (length == 6)
278 {
279 uint32_t asyncmap = ntohl(*(uint32_t *)(o + 2));
280 LOG(4, 0, 0, " %s %x\n", lcp_type(type), asyncmap);
281 }
282 else
283 LOG(4, 0, 0, " %s odd length %d\n", lcp_type(type), length);
284 break;
285 case 3: // Authentication-Protocol
286 if (length == 4)
287 {
288 int proto = ntohs(*(uint16_t *)(o + 2));
289 LOG(4, 0, 0, " %s 0x%x (%s)\n", lcp_type(type), proto,
290 proto == PPPPAP ? "PAP" : "UNSUPPORTED");
291 }
292 else if (length == 5)
293 {
294 int proto = ntohs(*(uint16_t *)(o + 2));
295 int algo = *(uint8_t *)(o + 4);
296 LOG(4, 0, 0, " %s 0x%x 0x%x (%s)\n", lcp_type(type), proto, algo,
297 (proto == PPPCHAP && algo == 5) ? "CHAP MD5" : "UNSUPPORTED");
298 }
299 else
300 LOG(4, 0, 0, " %s odd length %d\n", lcp_type(type), length);
301 break;
302 case 4: // Quality-Protocol
303 {
304 uint32_t qp = ntohl(*(uint32_t *)(o + 2));
305 LOG(4, 0, 0, " %s %x\n", lcp_type(type), qp);
306 }
307 break;
308 case 5: // Magic-Number
309 if (length == 6)
310 {
311 uint32_t magicno = ntohl(*(uint32_t *)(o + 2));
312 LOG(4, 0, 0, " %s %x\n", lcp_type(type), magicno);
313 }
314 else
315 LOG(4, 0, 0, " %s odd length %d\n", lcp_type(type), length);
316 break;
317 case 7: // Protocol-Field-Compression
318 case 8: // Address-And-Control-Field-Compression
319 LOG(4, 0, 0, " %s\n", lcp_type(type));
320 break;
321 default:
322 LOG(2, 0, 0, " Unknown PPP LCP Option type %d\n", type);
323 break;
324 }
325 x -= length;
326 o += length;
327 }
328 }
329
330 // Process LCP messages
331 void processlcp(tunnelidt t, sessionidt s, uint8_t *p, uint16_t l)
332 {
333 uint8_t b[MAXCONTROL];
334 uint8_t *q = NULL;
335 uint32_t magicno = 0;
336 uint16_t hl;
337
338 CSTAT(processlcp);
339
340 LOG_HEX(5, "LCP", p, l);
341 if (l < 4)
342 {
343 LOG(1, s, t, "Short LCP %d bytes\n", l);
344 STAT(tunnel_rx_errors);
345 return ;
346 }
347
348 if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
349 {
350 LOG(1, s, t, "Length mismatch LCP %u/%u\n", hl, l);
351 STAT(tunnel_rx_errors);
352 return ;
353 }
354 l = hl;
355
356 if (*p == ConfigAck)
357 {
358 LOG(3, s, t, "LCP: Discarding ConfigAck\n");
359 session[s].flags |= SF_LCP_ACKED;
360 }
361 else if (*p == ConfigReq)
362 {
363 int x = l - 4;
364 uint8_t *o = (p + 4);
365 uint8_t *response = 0;
366
367 LOG(3, s, t, "LCP: ConfigReq (%d bytes)...\n", l);
368 if (config->debug > 3) dumplcp(p, l);
369
370 while (x > 2)
371 {
372 int type = o[0];
373 int length = o[1];
374
375 if (length == 0 || type == 0 || x < length) break;
376 switch (type)
377 {
378 case 1: // Maximum-Receive-Unit
379 session[s].mru = ntohs(*(uint16_t *)(o + 2));
380 break;
381
382 case 2: // Async-Control-Character-Map
383 if (!ntohl(*(uint32_t *)(o + 2))) // all bits zero is OK
384 break;
385
386 if (response && *response != ConfigNak) // rej already queued
387 break;
388
389 LOG(2, s, t, " Remote requesting asyncmap. Rejecting.\n");
390 if (!response)
391 {
392 q = response = makeppp(b, sizeof(b), p, 2, t, s, PPPLCP);
393 if (!q) break;
394 *q = ConfigNak;
395 q += 4;
396 }
397
398 if ((q - b + 11) > sizeof(b))
399 {
400 LOG(2, s, t, "LCP overflow for asyncmap ConfigNak.\n");
401 break;
402 }
403
404 *q++ = type;
405 *q++ = 6;
406 memset(q, 0, 4); // asyncmap 0
407 q += 4;
408 break;
409
410 case 3: // Authentication-Protocol
411 {
412 int proto = ntohs(*(uint16_t *)(o + 2));
413 char proto_name[] = "0x0000";
414 uint8_t *a;
415
416 if (proto == PPPPAP)
417 {
418 if (config->radius_authtypes & AUTHPAP)
419 break;
420
421 strcpy(proto_name, "PAP");
422 }
423 else if (proto == PPPCHAP)
424 {
425 if (config->radius_authtypes & AUTHCHAP
426 && *(o + 4) == 5) // MD5
427 break;
428
429 strcpy(proto_name, "CHAP");
430 }
431 else
432 sprintf(proto_name, "%#4.4x", proto);
433
434 if (response && *response != ConfigNak) // rej already queued
435 break;
436
437 LOG(2, s, t, " Remote requesting %s authentication. Rejecting.\n", proto_name);
438
439 if (!response)
440 {
441 q = response = makeppp(b, sizeof(b), p, 2, t, s, PPPLCP);
442 if (!q) break;
443 *q = ConfigNak;
444 q += 4;
445 }
446
447 a = add_lcp_auth(q, sizeof(b) - (q - b), config->radius_authprefer);
448 if (!a)
449 {
450 LOG(2, s, t, "LCP overflow for %s ConfigNak.\n", proto_name);
451 break;
452 }
453
454 q = a;
455
456 if (config->radius_authtypes != config->radius_authprefer)
457 {
458 a = add_lcp_auth(q, sizeof(b) - (q - b), config->radius_authtypes & ~config->radius_authprefer);
459 if (!a)
460 {
461 LOG(2, s, t, "LCP overflow for %s ConfigNak.\n", proto_name);
462 break;
463 }
464
465 q = a;
466 }
467
468 break;
469 }
470 break;
471
472 case 5: // Magic-Number
473 magicno = ntohl(*(uint32_t *)(o + 2));
474 break;
475
476 case 4: // Quality-Protocol
477 case 7: // Protocol-Field-Compression
478 case 8: // Address-And-Control-Field-Compression
479 break;
480
481 default: // Reject any unknown options
482 LOG(2, s, t, " Rejecting PPP LCP Option type %d\n", type);
483 if (!response || *response != ConfigRej) // drop nak in favour of rej
484 {
485 q = response = makeppp(b, sizeof(b), p, 2, t, s, PPPLCP);
486 if (!q) break;
487 *q = ConfigRej;
488 q += 4;
489 }
490
491 if ((q - b + length) > sizeof(b))
492 {
493 LOG(2, s, t, "LCP overflow for ConfigRej (type=%d).\n", type);
494 break;
495 }
496
497 memcpy(q, o, length);
498 q += length;
499 }
500 x -= length;
501 o += length;
502 }
503
504 if (response)
505 {
506 l = q - response; // LCP packet length
507 *((uint16_t *) (response + 2)) = htons(l); // update header
508 }
509 else
510 {
511 // Send packet back as ConfigAck
512 response = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
513 if (!response) return;
514 *response = ConfigAck;
515 }
516
517 LOG(3, s, t, "Sending %s\n", ppp_lcp_type(*response));
518 tunnelsend(b, l + response - b, t);
519
520 if (!(session[s].flags & SF_LCP_ACKED))
521 sendlcp(t, s, config->radius_authprefer);
522 }
523 else if (*p == ConfigNak)
524 {
525 int x = l - 4;
526 uint8_t *o = (p + 4);
527 int authtype = 0;
528
529 LOG(3, s, t, "LCP: ConfigNak (%d bytes)...\n", l);
530 if (config->debug > 3) dumplcp(p, l);
531
532 while (x > 2)
533 {
534 int type = o[0];
535 int length = o[1];
536
537 if (length == 0 || type == 0 || x < length) break;
538 switch (type)
539 {
540 case 1: // Maximum-Receive-Unit
541 session[s].mru = ntohs(*(uint16_t *)(o + 2));
542 LOG(3, s, t, " Remote requested MRU of %u\n", session[s].mru);
543 break;
544
545 case 3: // Authentication-Protocol
546 if (authtype)
547 break;
548
549 {
550 int proto = ntohs(*(uint16_t *)(o + 2));
551 if (proto == PPPPAP)
552 {
553 authtype = config->radius_authtypes & AUTHPAP;
554 LOG(3, s, t, " Remote requested PAP authentication...%sing\n",
555 authtype ? "accept" : "reject");
556 }
557 else if (proto == PPPCHAP && *(o + 4) == 5)
558 {
559 authtype = config->radius_authtypes & AUTHCHAP;
560 LOG(3, s, t, " Remote requested CHAP authentication...%sing\n",
561 authtype ? "accept" : "reject");
562 }
563 else
564 {
565 LOG(3, s, t, " Rejecting unsupported authentication %#4x\n",
566 proto);
567 }
568 }
569
570 if (!authtype)
571 {
572 sessionshutdown(s, "Unsupported authentication.", 3, 0);
573 return;
574 }
575
576 break;
577
578 default:
579 LOG(2, s, t, " Remote NAKed LCP type %u?\n", type);
580 break;
581 }
582 }
583
584 if (!authtype)
585 authtype = config->radius_authprefer;
586
587 sendlcp(t, s, authtype);
588 }
589 else if (*p == TerminateReq)
590 {
591 LOG(3, s, t, "LCP: Received TerminateReq. Sending TerminateAck\n");
592 *p = TerminateAck; // close
593 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
594 if (!q) return;
595 tunnelsend(b, l + (q - b), t); // send it
596 sessionshutdown(s, "Remote end closed connection.", 3, 0);
597 }
598 else if (*p == TerminateAck)
599 {
600 sessionshutdown(s, "Connection closed.", 3, 0);
601 }
602 else if (*p == ProtocolRej)
603 {
604 if (*(uint16_t *) (p+4) == htons(PPPIPV6CP))
605 {
606 LOG(3, s, t, "IPv6 rejected\n");
607 session[s].flags |= SF_IPV6_NACKED;
608 }
609 else
610 {
611 LOG(1, s, t, "Unexpected LCP protocol reject 0x%X\n",
612 ntohs(*(uint16_t *) (p+4)));
613 STAT(tunnel_rx_errors);
614 }
615 }
616 else if (*p == EchoReq)
617 {
618 LOG(5, s, t, "LCP: Received EchoReq. Sending EchoReply\n");
619 *p = EchoReply; // reply
620 *(uint32_t *) (p + 4) = htonl(session[s].magic); // our magic number
621 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
622 if (!q) return;
623 tunnelsend(b, l + (q - b), t); // send it
624 }
625 else if (*p == EchoReply)
626 {
627 // Ignore it, last_packet time is set earlier than this.
628 }
629 else if (*p == IdentRequest)
630 {
631 *p = CodeRej;
632 if (l > MAXCONTROL)
633 {
634 LOG(1, s, t, "Truncated Ident Packet (length=%d) to 1400 bytes\n", l);
635 l = 1400;
636 }
637 q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
638 if (!q) return;
639 LOG_HEX(5, "LCPIdentRej", q, l + 4);
640 tunnelsend(b, 12 + 4 + l, t);
641 }
642 else
643 {
644 LOG(1, s, t, "Unexpected LCP code %d\n", *p);
645 STAT(tunnel_rx_errors);
646 }
647 }
648
649 // find a PPP option, returns point to option, or 0 if not found
650 static uint8_t *findppp(uint8_t *b, uint8_t mtype)
651 {
652 uint16_t l = ntohs(*(uint16_t *) (b + 2));
653 if (l < 4)
654 return 0;
655 b += 4;
656 l -= 4;
657 while (l)
658 {
659 if (l < b[1] || !b[1])
660 return 0; // faulty
661 if (*b == mtype)
662 return b;
663 l -= b[1];
664 b += b[1];
665 }
666 return 0;
667 }
668
669 // Process IPCP messages
670 void processipcp(tunnelidt t, sessionidt s, uint8_t *p, uint16_t l)
671 {
672 uint16_t hl;
673
674 CSTAT(processipcp);
675
676 LOG_HEX(5, "IPCP", p, l);
677 if (l < 5)
678 {
679 LOG(1, s, t, "Short IPCP %d bytes\n", l);
680 STAT(tunnel_rx_errors);
681 return ;
682 }
683
684 if ((hl = ntohs(*(uint16_t *) (p + 2))) > l)
685 {
686 LOG(1, s, t, "Length mismatch IPCP %u/%u\n", hl, l);
687 STAT(tunnel_rx_errors);
688 return ;
689 }
690 l = hl;
691
692 if (*p == ConfigAck)
693 {
694 // happy with our IPCP
695 uint16_t r = sess_local[s].radius;
696 if ((!r || radius[r].state == RADIUSIPCP) && !session[s].walled_garden)
697 {
698 if (!r)
699 r = radiusnew(s);
700 if (r)
701 radiussend(r, RADIUSSTART); // send radius start, having got IPCP at last
702 }
703 session[s].flags |= SF_IPCP_ACKED;
704
705 LOG(3, s, t, "IPCP Acked, session is now active\n");
706
707 // clear LCP_ACKED/CCP_ACKED flag for possible fast renegotiaion for routers
708 session[s].flags &= ~(SF_LCP_ACKED|SF_CCP_ACKED);
709
710 return;
711 }
712 if (*p != ConfigReq)
713 {
714 LOG(1, s, t, "Unexpected IPCP code %d\n", *p);
715 STAT(tunnel_rx_errors);
716 return ;
717 }
718 LOG(4, s, t, "IPCP ConfigReq received\n");
719
720 if (!session[s].ip)
721 {
722 LOG(3, s, t, "Waiting on radius reply\n");
723 return; // have to wait on RADIUS reply
724 }
725 // form a config reply quoting the IP in the session
726 {
727 uint8_t b[MAXCONTROL];
728 uint8_t *i, *q;
729
730 q = p + 4;
731 i = p + l;
732 while (q < i && q[1])
733 {
734 if (*q != 0x81 && *q != 0x83 && *q != 3)
735 break;
736 q += q[1];
737 }
738 if (q < i)
739 {
740 // reject
741 uint16_t n = 4;
742 i = p + l;
743 if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPIPCP)))
744 return;
745
746 *q = ConfigRej;
747 p += 4;
748 while (p < i && p[1])
749 {
750 if (*p != 0x81 && *p != 0x83 && *p != 3)
751 {
752 LOG(2, s, t, "IPCP reject %d\n", *p);
753 memcpy(q + n, p, p[1]);
754 n += p[1];
755 }
756 p += p[1];
757 }
758 *(uint16_t *) (q + 2) = htons(n);
759 LOG(4, s, t, "Sending ConfigRej\n");
760 tunnelsend(b, n + (q - b), t); // send it
761 }
762 else
763 {
764 LOG(4, s, t, "Sending ConfigAck\n");
765 *p = ConfigAck;
766 if ((i = findppp(p, 0x81))) // Primary DNS address
767 {
768 if (*(uint32_t *) (i + 2) != htonl(session[s].dns1))
769 {
770 *(uint32_t *) (i + 2) = htonl(session[s].dns1);
771 *p = ConfigNak;
772 LOG(5, s, t, " DNS1 = %s\n",
773 fmtaddr(htonl(session[s].dns1), 0));
774 }
775 }
776 if ((i = findppp(p, 0x83))) // Secondary DNS address (TBA, is it)
777 {
778 if (*(uint32_t *) (i + 2) != htonl(session[s].dns2))
779 {
780 *(uint32_t *) (i + 2) = htonl(session[s].dns2);
781 *p = ConfigNak;
782 LOG(5, s, t, " DNS2 = %s\n",
783 fmtaddr(htonl(session[s].dns2), 0));
784 }
785 }
786 i = findppp(p, 3); // IP address
787 if (!i || i[1] != 6)
788 {
789 LOG(1, s, t, "No IP in IPCP request\n");
790 STAT(tunnel_rx_errors);
791 return ;
792 }
793 if (*(uint32_t *) (i + 2) != htonl(session[s].ip))
794 {
795 *(uint32_t *) (i + 2) = htonl(session[s].ip);
796 *p = ConfigNak;
797 LOG(4, s, t, " No, a ConfigNak, client is requesting IP - sending %s\n",
798 fmtaddr(htonl(session[s].ip), 0));
799 }
800 if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPIPCP)))
801 return;
802
803 tunnelsend(b, l + (q - b), t); // send it
804 }
805 }
806 }
807
808 // Process IPV6CP messages
809 void processipv6cp(tunnelidt t, sessionidt s, uint8_t *p, uint16_t l)
810 {
811
812 CSTAT(processipv6cp);
813
814 LOG_HEX(5, "IPV6CP", p, l);
815 if (l < 4)
816 {
817 LOG(1, s, t, "Short IPV6CP %d bytes\n", l);
818 STAT(tunnel_rx_errors);
819 return ;
820 }
821 if (*p == ConfigAck)
822 {
823 // happy with our IPV6CP
824 session[s].flags |= SF_IPV6CP_ACKED;
825
826 LOG(3, s, t, "IPV6CP Acked, IPv6 is now active\n");
827 // Add a routed block if configured.
828 if (session[s].ipv6prefixlen)
829 {
830 route6set(s, session[s].ipv6route, session[s].ipv6prefixlen, 1);
831 session[s].flags |= SF_IPV6_ROUTED;
832 }
833
834 // Send an initial RA (TODO: Should we send these regularly?)
835 send_ipv6_ra(t, s, NULL);
836 return;
837 }
838 if (*p != ConfigReq)
839 {
840 LOG(1, s, t, "Unexpected IPV6CP code %d\n", *p);
841 STAT(tunnel_rx_errors);
842 return;
843 }
844
845 LOG(4, s, t, "IPV6CP ConfigReq received\n");
846 if (ntohs(*(uint16_t *) (p + 2)) > l)
847 {
848 LOG(1, s, t, "Length mismatch IPV6CP %d/%d\n", ntohs(*(uint16_t *) (p + 2)), l);
849 STAT(tunnel_rx_errors);
850 return ;
851 }
852 if (!session[s].ip)
853 {
854 LOG(3, s, t, "Waiting on radius reply\n");
855 return; // have to wait on RADIUS reply
856 }
857 // form a config reply quoting the IP in the session
858 {
859 uint8_t b[MAXCONTROL];
860 uint8_t *i,
861 *q;
862
863 l = ntohs(*(uint16_t *) (p + 2)); // We must use length from IPV6CP len field
864 q = p + 4;
865 i = p + l;
866 while (q < i && q[1])
867 {
868 if (*q != 1)
869 break;
870 q += q[1];
871 }
872 if (q < i)
873 {
874 // reject
875 uint16_t n = 4;
876 i = p + l;
877 if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPIPV6CP)))
878 {
879 LOG(2, s, t, "Failed to send IPV6CP ConfigRej\n");
880 return;
881 }
882 *q = ConfigRej;
883 p += 4;
884 while (p < i && p[1])
885 {
886 if (*p != 1)
887 {
888 LOG(2, s, t, "IPV6CP reject %d\n", *p);
889 memcpy(q + n, p, p[1]);
890 n += p[1];
891 }
892 p += p[1];
893 }
894 *(uint16_t *) (q + 2) = htons(n);
895 LOG(4, s, t, "Sending ConfigRej\n");
896 tunnelsend(b, n + (q - b), t); // send it
897 }
898 else
899 {
900 LOG(4, s, t, "Sending ConfigAck\n");
901 *p = ConfigAck;
902 i = findppp(p, 1); // IP address
903 if (!i || i[1] != 10)
904 {
905 LOG(1, s, t, "No IP in IPV6CP request\n");
906 STAT(tunnel_rx_errors);
907 return ;
908 }
909 if ((*(uint32_t *) (i + 2) != htonl(session[s].ip)) ||
910 (*(uint32_t *) (i + 6) != 0))
911 {
912 *(uint32_t *) (i + 2) = htonl(session[s].ip);
913 *(uint32_t *) (i + 6) = 0;
914 *p = ConfigNak;
915 LOG(4, s, t,
916 " No, a ConfigNak, client is "
917 "requesting IP - sending %s\n",
918 fmtaddr(htonl(session[s].ip), 0));
919 }
920 if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPIPV6CP)))
921 {
922 LOG(2, s, t, " Failed to send IPV6CP packet.\n");
923 return;
924 }
925 tunnelsend(b, l + (q - b), t); // send it
926 }
927 }
928 }
929
930 // process IP packet received
931 //
932 // This MUST be called with at least 4 byte behind 'p'.
933 // (i.e. this routine writes to p[-4]).
934 void processipin(tunnelidt t, sessionidt s, uint8_t *p, uint16_t l)
935 {
936 in_addr_t ip;
937
938 CSTAT(processipin);
939
940 LOG_HEX(5, "IP", p, l);
941
942 ip = ntohl(*(uint32_t *)(p + 12));
943
944 if (l > MAXETHER)
945 {
946 LOG(1, s, t, "IP packet too long %d\n", l);
947 STAT(tunnel_rx_errors);
948 return ;
949 }
950
951 // no spoof (do sessionbyip to handled statically routed subnets)
952 if (ip != session[s].ip && sessionbyip(htonl(ip)) != s)
953 {
954 LOG(5, s, t, "Dropping packet with spoofed IP %s\n", fmtaddr(htonl(ip), 0));
955 return;
956 }
957
958 // run access-list if any
959 if (session[s].filter_in && !ip_filter(p, l, session[s].filter_in - 1))
960 return;
961
962 // Add on the tun header
963 p -= 4;
964 *(uint32_t *) p = htonl(PKTIP);
965 l += 4;
966
967 // Are we throttled and a slave?
968 if (session[s].tbf_in && !config->cluster_iam_master) {
969 // Pass it to the master for handling.
970 master_throttle_packet(session[s].tbf_in, p, l);
971 return;
972 }
973
974 // Are we throttled and a master??
975 if (session[s].tbf_in && config->cluster_iam_master) {
976 // Actually handle the throttled packets.
977 tbf_queue_packet(session[s].tbf_in, p, l);
978 return;
979 }
980
981 // send to ethernet
982 if (tun_write(p, l) < 0)
983 {
984 STAT(tun_tx_errors);
985 LOG(0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
986 l, strerror(errno), tunfd, p);
987
988 return;
989 }
990
991 if (session[s].snoop_ip && session[s].snoop_port)
992 {
993 // Snooping this session
994 snoop_send_packet(p + 4, l - 4, session[s].snoop_ip, session[s].snoop_port);
995 }
996
997 session[s].cin += l - 4;
998 session[s].total_cin += l - 4;
999 sess_local[s].cin += l - 4;
1000
1001 session[s].pin++;
1002 eth_tx += l - 4;
1003
1004 STAT(tun_tx_packets);
1005 INC_STAT(tun_tx_bytes, l - 4);
1006 }
1007
1008 // process IPv6 packet received
1009 //
1010 // This MUST be called with at least 4 byte behind 'p'.
1011 // (i.e. this routine writes to p[-4]).
1012 void processipv6in(tunnelidt t, sessionidt s, uint8_t *p, uint16_t l)
1013 {
1014 struct in6_addr ip;
1015 in_addr_t ipv4;
1016
1017 CSTAT(processipv6in);
1018
1019 LOG_HEX(5, "IPv6", p, l);
1020
1021 ip = *(struct in6_addr *) (p + 8);
1022 ipv4 = ntohl(*(uint32_t *)(p + 16));
1023
1024 if (l > MAXETHER)
1025 {
1026 LOG(1, s, t, "IP packet too long %d\n", l);
1027 STAT(tunnel_rx_errors);
1028 return ;
1029 }
1030
1031 // no spoof
1032 if (ipv4 != session[s].ip && memcmp(&config->ipv6_prefix, &ip, 8) && sessionbyipv6(ip) != s)
1033 {
1034 char str[INET6_ADDRSTRLEN];
1035 LOG(5, s, t, "Dropping packet with spoofed IP %s\n",
1036 inet_ntop(AF_INET6, &ip, str, INET6_ADDRSTRLEN));
1037 return;
1038 }
1039
1040 // Check if it's a Router Solicition message.
1041 if (*(p + 6) == 58 && *(p + 7) == 255 && *(p + 24) == 0xFF && *(p + 25) == 2 &&
1042 *(uint32_t *)(p + 26) == 0 && *(uint32_t *)(p + 30) == 0 &&
1043 *(uint32_t *)(p + 34) == 0 &&
1044 *(p + 38) == 0 && *(p + 39) == 2 && *(p + 40) == 133) {
1045 LOG(3, s, t, "Got IPv6 RS\n");
1046 send_ipv6_ra(t, s, &ip);
1047 return;
1048 }
1049
1050 // Add on the tun header
1051 p -= 4;
1052 *(uint32_t *) p = htonl(PKTIPV6);
1053 l += 4;
1054
1055 // Are we throttled and a slave?
1056 if (session[s].tbf_in && !config->cluster_iam_master) {
1057 // Pass it to the master for handling.
1058 master_throttle_packet(session[s].tbf_in, p, l);
1059 return;
1060 }
1061
1062 // Are we throttled and a master??
1063 if (session[s].tbf_in && config->cluster_iam_master) {
1064 // Actually handle the throttled packets.
1065 tbf_queue_packet(session[s].tbf_in, p, l);
1066 return;
1067 }
1068
1069 // send to ethernet
1070 if (tun_write(p, l) < 0)
1071 {
1072 STAT(tun_tx_errors);
1073 LOG(0, s, t, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1074 l, strerror(errno), tunfd, p);
1075
1076 return;
1077 }
1078
1079 if (session[s].snoop_ip && session[s].snoop_port)
1080 {
1081 // Snooping this session
1082 snoop_send_packet(p + 4, l - 4, session[s].snoop_ip, session[s].snoop_port);
1083 }
1084
1085 session[s].cin += l - 4;
1086 session[s].total_cin += l - 4;
1087 sess_local[s].cin += l - 4;
1088
1089 session[s].pin++;
1090 eth_tx += l - 4;
1091
1092 STAT(tun_tx_packets);
1093 INC_STAT(tun_tx_bytes, l - 4);
1094 }
1095
1096 //
1097 // Helper routine for the TBF filters.
1098 // Used to send queued data in from the user.
1099 //
1100 void send_ipin(sessionidt s, uint8_t *buf, int len)
1101 {
1102 LOG_HEX(5, "IP in throttled", buf, len);
1103
1104 if (write(tunfd, buf, len) < 0)
1105 {
1106 STAT(tun_tx_errors);
1107 LOG(0, 0, 0, "Error writing %d bytes to TUN device: %s (tunfd=%d, p=%p)\n",
1108 len, strerror(errno), tunfd, buf);
1109
1110 return;
1111 }
1112
1113 if (session[s].snoop_ip && session[s].snoop_port)
1114 {
1115 // Snooping this session
1116 snoop_send_packet(buf + 4, len - 4, session[s].snoop_ip, session[s].snoop_port);
1117 }
1118
1119 // Increment packet counters
1120 session[s].cin += len - 4;
1121 session[s].total_cin += len - 4;
1122 sess_local[s].cin += len - 4;
1123
1124 session[s].pin++;
1125 eth_tx += len - 4;
1126
1127 STAT(tun_tx_packets);
1128 INC_STAT(tun_tx_bytes, len - 4);
1129 }
1130
1131
1132 // Process CCP messages
1133 void processccp(tunnelidt t, sessionidt s, uint8_t *p, uint16_t l)
1134 {
1135 uint8_t b[MAXCONTROL];
1136 uint8_t *q;
1137
1138 CSTAT(processccp);
1139
1140 LOG_HEX(5, "CCP", p, l);
1141 switch (l > 1 ? *p : 0)
1142 {
1143 case ConfigAck:
1144 session[s].flags |= SF_CCP_ACKED;
1145 return;
1146
1147 case ConfigReq:
1148 if (l < 6) // accept no compression
1149 {
1150 *p = ConfigAck;
1151 break;
1152 }
1153
1154 // compression requested--reject
1155 *p = ConfigRej;
1156
1157 // send CCP request for no compression for our end if not negotiated
1158 if (!(session[s].flags & SF_CCP_ACKED))
1159 initccp(t, s);
1160
1161 break;
1162
1163 case TerminateReq:
1164 *p = TerminateAck;
1165 break;
1166
1167 default:
1168 if (l > 1)
1169 LOG(1, s, t, "Unexpected CCP request code %d\n", *p);
1170 else
1171 LOG(1, s, t, "Short CCP packet\n");
1172
1173 STAT(tunnel_rx_errors);
1174 return;
1175 }
1176
1177 if (!(q = makeppp(b, sizeof(b), p, l, t, s, PPPCCP)))
1178 return;
1179
1180 tunnelsend(b, l + (q - b), t); // send it
1181 }
1182
1183 // send a CHAP challenge
1184 void sendchap(tunnelidt t, sessionidt s)
1185 {
1186 uint8_t b[MAXCONTROL];
1187 uint16_t r = sess_local[s].radius;
1188 uint8_t *q;
1189
1190 CSTAT(sendchap);
1191
1192 if (!r)
1193 {
1194 LOG(1, s, t, "No RADIUS to send challenge\n");
1195 STAT(tunnel_tx_errors);
1196 return;
1197 }
1198
1199 LOG(1, s, t, "Send CHAP challenge\n");
1200
1201 radius[r].chap = 1; // CHAP not PAP
1202 radius[r].id++;
1203 if (radius[r].state != RADIUSCHAP)
1204 radius[r].try = 0;
1205
1206 radius[r].state = RADIUSCHAP;
1207 radius[r].retry = backoff(radius[r].try++);
1208 if (radius[r].try > 5)
1209 {
1210 sessionshutdown(s, "CHAP timeout.", 3, 0);
1211 STAT(tunnel_tx_errors);
1212 return ;
1213 }
1214 q = makeppp(b, sizeof(b), 0, 0, t, s, PPPCHAP);
1215 if (!q) return;
1216
1217 *q = 1; // challenge
1218 q[1] = radius[r].id; // ID
1219 q[4] = 16; // value size (size of challenge)
1220 memcpy(q + 5, radius[r].auth, 16); // challenge
1221 strcpy(q + 21, hostname); // our name
1222 *(uint16_t *) (q + 2) = htons(strlen(hostname) + 21); // length
1223 tunnelsend(b, strlen(hostname) + 21 + (q - b), t); // send it
1224 }
1225
1226 // fill in a L2TP message with a PPP frame,
1227 // copies existing PPP message and changes magic number if seen
1228 // returns start of PPP frame
1229 uint8_t *makeppp(uint8_t *b, int size, uint8_t *p, int l, tunnelidt t, sessionidt s, uint16_t mtype)
1230 {
1231 if (size < 12) // Need more space than this!!
1232 {
1233 static int backtrace_count = 0;
1234 LOG(0, s, t, "makeppp buffer too small for L2TP header (size=%d)\n", size);
1235 log_backtrace(backtrace_count, 5)
1236 return NULL;
1237 }
1238
1239 *(uint16_t *) (b + 0) = htons(0x0002); // L2TP with no options
1240 *(uint16_t *) (b + 2) = htons(tunnel[t].far); // tunnel
1241 *(uint16_t *) (b + 4) = htons(session[s].far); // session
1242 b += 6;
1243 if (mtype == PPPLCP || !(session[s].l2tp_flags & SESSIONACFC))
1244 {
1245 *(uint16_t *) b = htons(0xFF03); // HDLC header
1246 b += 2;
1247 }
1248 if (mtype < 0x100 && session[s].l2tp_flags & SESSIONPFC)
1249 *b++ = mtype;
1250 else
1251 {
1252 *(uint16_t *) b = htons(mtype);
1253 b += 2;
1254 }
1255
1256 if (l + 12 > size)
1257 {
1258 static int backtrace_count = 0;
1259 LOG(2, s, t, "makeppp would overflow buffer (size=%d, header+payload=%d)\n", size, l + 12);
1260 log_backtrace(backtrace_count, 5)
1261 return NULL;
1262 }
1263
1264 if (p && l)
1265 memcpy(b, p, l);
1266
1267 return b;
1268 }
1269
1270 static uint8_t *add_lcp_auth(uint8_t *b, int size, int authtype)
1271 {
1272 if ((authtype == AUTHCHAP && size < 5) || size < 4)
1273 return 0;
1274
1275 *b++ = 3; // Authentication-Protocol
1276 if (authtype == AUTHCHAP)
1277 {
1278 *b++ = 5; // length
1279 *(uint16_t *) b = htons(PPPCHAP); b += 2;
1280 *b++ = 5; // MD5
1281 }
1282 else if (authtype == AUTHPAP)
1283 {
1284 *b++ = 4; // length
1285 *(uint16_t *) b = htons(PPPPAP); b += 2;
1286 }
1287 else
1288 {
1289 LOG(0, 0, 0, "add_lcp_auth called with unsupported auth type %d\n", authtype);
1290 }
1291
1292 return b;
1293 }
1294
1295 // Send initial LCP ConfigReq for MRU, authentication type and magic no
1296 void sendlcp(tunnelidt t, sessionidt s, int authtype)
1297 {
1298 char b[500], *q, *l;
1299
1300 if (!(q = makeppp(b, sizeof(b), NULL, 0, t, s, PPPLCP)))
1301 return;
1302
1303 LOG(4, s, t, "Sending LCP ConfigReq for %s\n",
1304 config->radius_authprefer == AUTHCHAP ? "CHAP" : "PAP");
1305
1306 if (!session[s].mru)
1307 session[s].mru = DEFAULT_MRU;
1308
1309 l = q;
1310 *l++ = ConfigReq;
1311 *l++ = (time_now % 255) + 1; // ID
1312
1313 l += 2; //Save space for length
1314
1315 *l++ = 1; *l++ = 4; // Maximum-Receive-Unit (length 4)
1316 *(uint16_t *) l = htons(session[s].mru); l += 2;
1317
1318 l = add_lcp_auth(l, sizeof(b) - (l - b), authtype);
1319
1320 *l++ = 5; *l++ = 6; // Magic-Number (length 6)
1321 *(uint32_t *) l = htonl(session[s].magic);
1322 l += 4;
1323
1324 *(uint16_t *)(q + 2) = htons(l - q); // Length
1325
1326 LOG_HEX(5, "PPPLCP", q, l - q);
1327 tunnelsend(b, (l - b), t);
1328 }
1329
1330 // Send CCP request for no compression
1331 static void initccp(tunnelidt t, sessionidt s)
1332 {
1333 char b[500], *q;
1334
1335 if (!(q = makeppp(b, sizeof(b), NULL, 0, t, s, PPPCCP)))
1336 return;
1337
1338 LOG(4, s, t, "Sending CCP ConfigReq for no compression\n");
1339 *q = ConfigReq;
1340 *(uint8_t *)(q + 1) = (time_now % 255) + 1; // ID
1341 *(uint16_t *)(q + 2) = htons(4); // Length
1342
1343 LOG_HEX(5, "PPPCCP", q, 4);
1344 tunnelsend(b, (q - b) + 4 , t);
1345 }
for cloning use: "git clone git://git.sameswireless.fr/l2tpns.git" ; For add to your sources.list: "deb http://package.sameswifi.fr/ jessie main"