Only read our public key if it wasn't already in the private key file.
[tinc] / src / net_packet.c
1 /*
2     net_packet.c -- Handles in- and outgoing VPN packets
3     Copyright (C) 1998-2003 Ivo Timmermans <ivo@o2w.nl>,
4                   2000-2003 Guus Sliepen <guus@sliepen.eu.org>
5
6     This program is free software; you can redistribute it and/or modify
7     it under the terms of the GNU General Public License as published by
8     the Free Software Foundation; either version 2 of the License, or
9     (at your option) any later version.
10
11     This program is distributed in the hope that it will be useful,
12     but WITHOUT ANY WARRANTY; without even the implied warranty of
13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14     GNU General Public License for more details.
15
16     You should have received a copy of the GNU General Public License
17     along with this program; if not, write to the Free Software
18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19
20     $Id: net_packet.c,v 1.1.2.49 2003/12/27 16:32:52 guus Exp $
21 */
22
23 #include "system.h"
24
25 #include <openssl/rand.h>
26 #include <openssl/err.h>
27 #include <openssl/evp.h>
28 #include <openssl/pem.h>
29 #include <openssl/hmac.h>
30
31 #include <zlib.h>
32 #include <lzo1x.h>
33
34 #include "avl_tree.h"
35 #include "conf.h"
36 #include "connection.h"
37 #include "device.h"
38 #include "ethernet.h"
39 #include "event.h"
40 #include "graph.h"
41 #include "list.h"
42 #include "logger.h"
43 #include "net.h"
44 #include "netutl.h"
45 #include "protocol.h"
46 #include "process.h"
47 #include "route.h"
48 #include "utils.h"
49 #include "xalloc.h"
50
51 #ifdef WSAEMSGSIZE
52 #define EMSGSIZE WSAEMSGSIZE
53 #endif
54
55 int keylifetime = 0;
56 int keyexpires = 0;
57 EVP_CIPHER_CTX packet_ctx;
58 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
59
60 static void send_udppacket(node_t *, vpn_packet_t *);
61
62 #define MAX_SEQNO 1073741824
63
64 void send_mtu_probe(node_t *n)
65 {
66         vpn_packet_t packet;
67         int len, i;
68         
69         cp();
70
71         n->mtuprobes++;
72         n->mtuevent = NULL;
73
74         if(n->mtuprobes >= 10 && !n->minmtu) {
75                 ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname);
76                 return;
77         }
78
79         for(i = 0; i < 3; i++) {
80                 if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) {
81                         n->mtu = n->minmtu;
82                         ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
83                         return;
84                 }
85
86                 len = n->minmtu + 1 + random() % (n->maxmtu - n->minmtu);
87                 if(len < 64)
88                         len = 64;
89                 
90                 memset(packet.data, 0, 14);
91                 RAND_pseudo_bytes(packet.data + 14, len - 14);
92                 packet.len = len;
93
94                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
95
96                 send_udppacket(n, &packet);
97         }
98
99         n->mtuevent = xmalloc(sizeof(*n->mtuevent));
100         n->mtuevent->handler = (event_handler_t)send_mtu_probe;
101         n->mtuevent->data = n;
102         n->mtuevent->time = now + 1;
103         event_add(n->mtuevent);
104 }
105
106 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
107         ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
108
109         if(!packet->data[0]) {
110                 packet->data[0] = 1;
111                 send_packet(n, packet);
112         } else {
113                 if(n->minmtu < packet->len)
114                         n->minmtu = packet->len;
115         }
116 }
117
118 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
119 {
120         if(level == 10) {
121                 lzo_uint lzolen = MAXSIZE;
122                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
123                 return lzolen;
124         } else if(level < 10) {
125                 unsigned long destlen = MAXSIZE;
126                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
127                         return destlen;
128                 else
129                         return -1;
130         } else {
131                 lzo_uint lzolen = MAXSIZE;
132                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
133                 return lzolen;
134         }
135         
136         return -1;
137 }
138
139 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
140 {
141         if(level > 9) {
142                 lzo_uint lzolen = MAXSIZE;
143                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
144                         return lzolen;
145                 else
146                         return -1;
147         } else {
148                 unsigned long destlen = MAXSIZE;
149                 if(uncompress(dest, &destlen, source, len) == Z_OK)
150                         return destlen;
151                 else
152                         return -1;
153         }
154         
155         return -1;
156 }
157
158 /* VPN packet I/O */
159
160 static void receive_packet(node_t *n, vpn_packet_t *packet)
161 {
162         cp();
163
164         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
165                            packet->len, n->name, n->hostname);
166
167         route(n, packet);
168 }
169
170 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
171 {
172         vpn_packet_t pkt1, pkt2;
173         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
174         int nextpkt = 0;
175         vpn_packet_t *outpkt = pkt[0];
176         int outlen, outpad;
177         char hmac[EVP_MAX_MD_SIZE];
178         int i;
179
180         cp();
181
182         /* Check packet length */
183
184         if(inpkt->len < sizeof(inpkt->seqno) + myself->maclength) {
185                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
186                                         n->name, n->hostname);
187                 return;
188         }
189
190         /* Check the message authentication code */
191
192         if(myself->digest && myself->maclength) {
193                 inpkt->len -= myself->maclength;
194                 HMAC(myself->digest, myself->key, myself->keylength,
195                          (char *) &inpkt->seqno, inpkt->len, hmac, NULL);
196
197                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
198                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
199                                            n->name, n->hostname);
200                         return;
201                 }
202         }
203
204         /* Decrypt the packet */
205
206         if(myself->cipher) {
207                 outpkt = pkt[nextpkt++];
208
209                 if(!EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL)
210                                 || !EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
211                                         (char *) &inpkt->seqno, inpkt->len)
212                                 || !EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
213                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
214                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
215                         return;
216                 }
217                 
218                 outpkt->len = outlen + outpad;
219                 inpkt = outpkt;
220         }
221
222         /* Check the sequence number */
223
224         inpkt->len -= sizeof(inpkt->seqno);
225         inpkt->seqno = ntohl(inpkt->seqno);
226
227         if(inpkt->seqno != n->received_seqno + 1) {
228                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
229                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
230                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
231                         
232                         memset(n->late, 0, sizeof(n->late));
233                 } else if (inpkt->seqno <= n->received_seqno) {
234                         if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
235                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
236                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
237                         } else
238                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
239                                         n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
240                 }
241         }
242         
243         n->received_seqno = inpkt->seqno;
244         n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
245                         
246         if(n->received_seqno > MAX_SEQNO)
247                 keyexpires = 0;
248
249         /* Decompress the packet */
250
251         if(myself->compression) {
252                 outpkt = pkt[nextpkt++];
253
254                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
255                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
256                                                  n->name, n->hostname);
257                         return;
258                 }
259
260                 inpkt = outpkt;
261         }
262
263         if(n->connection)
264                 n->connection->last_ping_time = now;
265
266         if(!inpkt->data[12] && !inpkt->data[13])
267                 mtu_probe_h(n, inpkt);
268         else
269                 receive_packet(n, inpkt);
270 }
271
272 void receive_tcppacket(connection_t *c, char *buffer, int len)
273 {
274         vpn_packet_t outpkt;
275
276         cp();
277
278         outpkt.len = len;
279         memcpy(outpkt.data, buffer, len);
280
281         receive_packet(c->node, &outpkt);
282 }
283
284 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
285 {
286         vpn_packet_t pkt1, pkt2;
287         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
288         int nextpkt = 0;
289         vpn_packet_t *outpkt;
290         int origlen;
291         int outlen, outpad;
292         vpn_packet_t *copy;
293         static int priority = 0;
294         int origpriority;
295         int sock;
296
297         cp();
298
299         /* Make sure we have a valid key */
300
301         if(!n->status.validkey) {
302                 ifdebug(TRAFFIC) logger(LOG_INFO,
303                                    _("No valid key known yet for %s (%s), queueing packet"),
304                                    n->name, n->hostname);
305
306                 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
307
308                 *(copy = xmalloc(sizeof(*copy))) = *inpkt;
309
310                 list_insert_tail(n->queue, copy);
311
312                 if(n->queue->count > MAXQUEUELENGTH)
313                         list_delete_head(n->queue);
314
315                 if(!n->status.waitingforkey)
316                         send_req_key(n->nexthop->connection, myself, n);
317
318                 n->status.waitingforkey = true;
319
320                 return;
321         }
322
323         origlen = inpkt->len;
324         origpriority = inpkt->priority;
325
326         /* Compress the packet */
327
328         if(n->compression) {
329                 outpkt = pkt[nextpkt++];
330
331                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
332                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
333                                    n->name, n->hostname);
334                         return;
335                 }
336
337                 inpkt = outpkt;
338         }
339
340         /* Add sequence number */
341
342         inpkt->seqno = htonl(++(n->sent_seqno));
343         inpkt->len += sizeof(inpkt->seqno);
344
345         /* Encrypt the packet */
346
347         if(n->cipher) {
348                 outpkt = pkt[nextpkt++];
349
350                 if(!EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL)
351                                 || !EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
352                                         (char *) &inpkt->seqno, inpkt->len)
353                                 || !EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
354                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
355                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
356                         goto end;
357                 }
358
359                 outpkt->len = outlen + outpad;
360                 inpkt = outpkt;
361         }
362
363         /* Add the message authentication code */
364
365         if(n->digest && n->maclength) {
366                 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
367                          inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
368                 inpkt->len += n->maclength;
369         }
370
371         /* Determine which socket we have to use */
372
373         for(sock = 0; sock < listen_sockets; sock++)
374                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
375                         break;
376
377         if(sock >= listen_sockets)
378                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
379
380         /* Send the packet */
381
382 #if defined(SOL_IP) && defined(IP_TOS)
383         if(priorityinheritance && origpriority != priority
384            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
385                 priority = origpriority;
386                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
387                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
388                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
389         }
390 #endif
391
392         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
393                 if(errno == EMSGSIZE) {
394                         if(n->maxmtu >= origlen)
395                                 n->maxmtu = origlen - 1;
396                         if(n->mtu >= origlen)
397                                 n->mtu = origlen - 1;
398                 } else
399                         logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
400         }
401
402 end:
403         inpkt->len = origlen;
404 }
405
406 /*
407   send a packet to the given vpn ip.
408 */
409 void send_packet(const node_t *n, vpn_packet_t *packet)
410 {
411         node_t *via;
412
413         cp();
414
415         if(n == myself) {
416                 if(overwrite_mac)
417                          memcpy(packet->data, mymac.x, ETH_ALEN);
418                 write_packet(packet);
419                 return;
420         }
421
422         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
423                            packet->len, n->name, n->hostname);
424
425         if(!n->status.reachable) {
426                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
427                                    n->name, n->hostname);
428                 return;
429         }
430
431         via = (n->via == myself) ? n->nexthop : n->via;
432
433         if(via != n)
434                 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
435                            n->name, via->name, n->via->hostname);
436
437         if((myself->options | via->options) & OPTION_TCPONLY) {
438                 if(!send_tcppacket(via->connection, packet))
439                         terminate_connection(via->connection, true);
440         } else
441                 send_udppacket(via, packet);
442 }
443
444 /* Broadcast a packet using the minimum spanning tree */
445
446 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
447 {
448         avl_node_t *node;
449         connection_t *c;
450
451         cp();
452
453         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
454                            packet->len, from->name, from->hostname);
455
456         for(node = connection_tree->head; node; node = node->next) {
457                 c = node->data;
458
459                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
460                         send_packet(c->node, packet);
461         }
462 }
463
464 void flush_queue(node_t *n)
465 {
466         list_node_t *node, *next;
467
468         cp();
469
470         ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
471
472         for(node = n->queue->head; node; node = next) {
473                 next = node->next;
474                 send_udppacket(n, node->data);
475                 list_delete_node(n->queue, node);
476         }
477 }
478
479 void handle_incoming_vpn_data(int sock)
480 {
481         vpn_packet_t pkt;
482         char *hostname;
483         sockaddr_t from;
484         socklen_t fromlen = sizeof(from);
485         node_t *n;
486
487         cp();
488
489         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
490
491         if(pkt.len < 0) {
492                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
493                 return;
494         }
495
496         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
497
498         n = lookup_node_udp(&from);
499
500         if(!n) {
501                 hostname = sockaddr2hostname(&from);
502                 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
503                            hostname);
504                 free(hostname);
505                 return;
506         }
507
508         receive_udppacket(n, &pkt);
509 }