2 net_packet.c -- Handles in- and outgoing VPN packets
3 Copyright (C) 1998-2005 Ivo Timmermans,
4 2000-2010 Guus Sliepen <guus@tinc-vpn.org>
5 2010 Timothy Redaelli <timothy@redaelli.eu>
6 2010 Brandon Black <blblack@gmail.com>
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License along
19 with this program; if not, write to the Free Software Foundation, Inc.,
20 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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>
41 #include "connection.h"
59 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
62 static void send_udppacket(node_t *, vpn_packet_t *);
64 unsigned replaywin = 16;
66 #define MAX_SEQNO 1073741824
68 // mtuprobes == 1..30: initial discovery, send bursts with 1 second interval
69 // mtuprobes == 31: sleep pinginterval seconds
70 // mtuprobes == 32: send 1 burst, sleep pingtimeout second
71 // mtuprobes == 33: no response from other side, restart PMTU discovery process
73 void send_mtu_probe(node_t *n) {
81 if(!n->status.reachable || !n->status.validkey) {
82 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send MTU probe to unreachable or rekeying node %s (%s)", n->name, n->hostname);
87 if(n->mtuprobes > 32) {
88 ifdebug(TRAFFIC) logger(LOG_INFO, "%s (%s) did not respond to UDP ping, restarting PMTU discovery", n->name, n->hostname);
94 if(n->mtuprobes >= 10 && !n->minmtu) {
95 ifdebug(TRAFFIC) logger(LOG_INFO, "No response to MTU probes from %s (%s)", n->name, n->hostname);
100 if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) {
101 if(n->minmtu > n->maxmtu)
102 n->minmtu = n->maxmtu;
104 n->maxmtu = n->minmtu;
106 ifdebug(TRAFFIC) logger(LOG_INFO, "Fixing MTU of %s (%s) to %d after %d probes", n->name, n->hostname, n->mtu, n->mtuprobes);
110 if(n->mtuprobes == 31) {
111 timeout = pinginterval;
113 } else if(n->mtuprobes == 32) {
114 timeout = pingtimeout;
117 for(i = 0; i < 3; i++) {
118 if(n->maxmtu <= n->minmtu)
121 len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
126 memset(packet.data, 0, 14);
127 RAND_pseudo_bytes(packet.data + 14, len - 14);
131 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
133 send_udppacket(n, &packet);
137 n->mtuevent = new_event();
138 n->mtuevent->handler = (event_handler_t)send_mtu_probe;
139 n->mtuevent->data = n;
140 n->mtuevent->time = now + timeout;
141 event_add(n->mtuevent);
144 void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
145 ifdebug(TRAFFIC) logger(LOG_INFO, "Got MTU probe length %d from %s (%s)", packet->len, n->name, n->hostname);
147 if(!packet->data[0]) {
149 send_udppacket(n, packet);
155 if(n->mtuprobes > 30)
160 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
162 memcpy(dest, source, len);
164 } else if(level == 10) {
166 lzo_uint lzolen = MAXSIZE;
167 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
172 } else if(level < 10) {
174 unsigned long destlen = MAXSIZE;
175 if(compress2(dest, &destlen, source, len, level) == Z_OK)
182 lzo_uint lzolen = MAXSIZE;
183 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
193 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
195 memcpy(dest, source, len);
197 } else if(level > 9) {
199 lzo_uint lzolen = MAXSIZE;
200 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
208 unsigned long destlen = MAXSIZE;
209 if(uncompress(dest, &destlen, source, len) == Z_OK)
221 static void receive_packet(node_t *n, vpn_packet_t *packet) {
222 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Received packet of %d bytes from %s (%s)",
223 packet->len, n->name, n->hostname);
228 static bool try_mac(const node_t *n, const vpn_packet_t *inpkt) {
229 unsigned char hmac[EVP_MAX_MD_SIZE];
231 if(!n->indigest || !n->inmaclength || !n->inkey || inpkt->len < sizeof inpkt->seqno + n->inmaclength)
234 HMAC(n->indigest, n->inkey, n->inkeylength, (unsigned char *) &inpkt->seqno, inpkt->len - n->inmaclength, (unsigned char *)hmac, NULL);
236 return !memcmp(hmac, (char *) &inpkt->seqno + inpkt->len - n->inmaclength, n->inmaclength);
239 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
240 vpn_packet_t pkt1, pkt2;
241 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
243 vpn_packet_t *outpkt = pkt[0];
245 unsigned char hmac[EVP_MAX_MD_SIZE];
249 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet",
250 n->name, n->hostname);
254 /* Check packet length */
256 if(inpkt->len < sizeof(inpkt->seqno) + n->inmaclength) {
257 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got too short packet from %s (%s)",
258 n->name, n->hostname);
262 /* Check the message authentication code */
264 if(n->indigest && n->inmaclength) {
265 inpkt->len -= n->inmaclength;
266 HMAC(n->indigest, n->inkey, n->inkeylength,
267 (unsigned char *) &inpkt->seqno, inpkt->len, (unsigned char *)hmac, NULL);
269 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, n->inmaclength)) {
270 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got unauthenticated packet from %s (%s)",
271 n->name, n->hostname);
276 /* Decrypt the packet */
279 outpkt = pkt[nextpkt++];
281 if(!EVP_DecryptInit_ex(&n->inctx, NULL, NULL, NULL, NULL)
282 || !EVP_DecryptUpdate(&n->inctx, (unsigned char *) &outpkt->seqno, &outlen,
283 (unsigned char *) &inpkt->seqno, inpkt->len)
284 || !EVP_DecryptFinal_ex(&n->inctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
285 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Error decrypting packet from %s (%s): %s",
286 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
290 outpkt->len = outlen + outpad;
294 /* Check the sequence number */
296 inpkt->len -= sizeof(inpkt->seqno);
297 inpkt->seqno = ntohl(inpkt->seqno);
300 if(inpkt->seqno != n->received_seqno + 1) {
301 if(inpkt->seqno >= n->received_seqno + replaywin * 8) {
302 if(n->farfuture++ < replaywin >> 2) {
303 logger(LOG_WARNING, "Packet from %s (%s) is %d seqs in the future, dropped (%u)",
304 n->name, n->hostname, inpkt->seqno - n->received_seqno - 1, n->farfuture);
307 logger(LOG_WARNING, "Lost %d packets from %s (%s)",
308 inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
309 memset(n->late, 0, replaywin);
310 } else if (inpkt->seqno <= n->received_seqno) {
311 if((n->received_seqno >= replaywin * 8 && inpkt->seqno <= n->received_seqno - replaywin * 8) || !(n->late[(inpkt->seqno / 8) % replaywin] & (1 << inpkt->seqno % 8))) {
312 logger(LOG_WARNING, "Got late or replayed packet from %s (%s), seqno %d, last received %d",
313 n->name, n->hostname, inpkt->seqno, n->received_seqno);
317 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
318 n->late[(i / 8) % replaywin] |= 1 << i % 8;
323 n->late[(inpkt->seqno / 8) % replaywin] &= ~(1 << inpkt->seqno % 8);
326 if(inpkt->seqno > n->received_seqno)
327 n->received_seqno = inpkt->seqno;
329 if(n->received_seqno > MAX_SEQNO)
332 /* Decompress the packet */
334 length_t origlen = inpkt->len;
336 if(n->incompression) {
337 outpkt = pkt[nextpkt++];
339 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
340 ifdebug(TRAFFIC) logger(LOG_ERR, "Error while uncompressing packet from %s (%s)",
341 n->name, n->hostname);
347 origlen -= MTU/64 + 20;
352 if(!inpkt->data[12] && !inpkt->data[13])
353 mtu_probe_h(n, inpkt, origlen);
355 receive_packet(n, inpkt);
358 void receive_tcppacket(connection_t *c, char *buffer, int len) {
362 if(c->options & OPTION_TCPONLY)
365 outpkt.priority = -1;
366 memcpy(outpkt.data, buffer, len);
368 receive_packet(c->node, &outpkt);
371 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
372 vpn_packet_t pkt1, pkt2;
373 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
374 vpn_packet_t *inpkt = origpkt;
376 vpn_packet_t *outpkt;
379 #if defined(SOL_IP) && defined(IP_TOS)
380 static int priority = 0;
385 if(!n->status.reachable) {
386 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send UDP packet to unreachable node %s (%s)", n->name, n->hostname);
390 /* Make sure we have a valid key */
392 if(!n->status.validkey) {
393 ifdebug(TRAFFIC) logger(LOG_INFO,
394 "No valid key known yet for %s (%s), forwarding via TCP",
395 n->name, n->hostname);
397 if(n->last_req_key + 10 < now) {
399 n->last_req_key = now;
402 send_tcppacket(n->nexthop->connection, origpkt);
407 if(n->options & OPTION_PMTU_DISCOVERY && inpkt->len > n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
408 ifdebug(TRAFFIC) logger(LOG_INFO,
409 "Packet for %s (%s) larger than minimum MTU, forwarding via %s",
410 n->name, n->hostname, n != n->nexthop ? n->nexthop->name : "TCP");
413 send_packet(n->nexthop, origpkt);
415 send_tcppacket(n->nexthop->connection, origpkt);
420 origlen = inpkt->len;
421 origpriority = inpkt->priority;
423 /* Compress the packet */
425 if(n->outcompression) {
426 outpkt = pkt[nextpkt++];
428 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
429 ifdebug(TRAFFIC) logger(LOG_ERR, "Error while compressing packet to %s (%s)",
430 n->name, n->hostname);
437 /* Add sequence number */
439 inpkt->seqno = htonl(++(n->sent_seqno));
440 inpkt->len += sizeof(inpkt->seqno);
442 /* Encrypt the packet */
445 outpkt = pkt[nextpkt++];
447 if(!EVP_EncryptInit_ex(&n->outctx, NULL, NULL, NULL, NULL)
448 || !EVP_EncryptUpdate(&n->outctx, (unsigned char *) &outpkt->seqno, &outlen,
449 (unsigned char *) &inpkt->seqno, inpkt->len)
450 || !EVP_EncryptFinal_ex(&n->outctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
451 ifdebug(TRAFFIC) logger(LOG_ERR, "Error while encrypting packet to %s (%s): %s",
452 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
456 outpkt->len = outlen + outpad;
460 /* Add the message authentication code */
462 if(n->outdigest && n->outmaclength) {
463 HMAC(n->outdigest, n->outkey, n->outkeylength, (unsigned char *) &inpkt->seqno,
464 inpkt->len, (unsigned char *) &inpkt->seqno + inpkt->len, NULL);
465 inpkt->len += n->outmaclength;
468 /* Determine which socket we have to use */
470 for(sock = 0; sock < listen_sockets; sock++)
471 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
474 if(sock >= listen_sockets)
475 sock = 0; /* If none is available, just use the first and hope for the best. */
477 /* Send the packet */
479 #if defined(SOL_IP) && defined(IP_TOS)
480 if(priorityinheritance && origpriority != priority
481 && listen_socket[sock].sa.sa.sa_family == AF_INET) {
482 priority = origpriority;
483 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting outgoing packet priority to %d", priority);
484 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */
485 logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
489 if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa)) < 0 && !sockwouldblock(sockerrno)) {
490 if(sockmsgsize(sockerrno)) {
491 if(n->maxmtu >= origlen)
492 n->maxmtu = origlen - 1;
493 if(n->mtu >= origlen)
494 n->mtu = origlen - 1;
496 logger(LOG_ERR, "Error sending packet to %s (%s): %s", n->name, n->hostname, sockstrerror(sockerrno));
500 origpkt->len = origlen;
504 send a packet to the given vpn ip.
506 void send_packet(const node_t *n, vpn_packet_t *packet) {
511 memcpy(packet->data, mymac.x, ETH_ALEN);
512 write_packet(packet);
516 ifdebug(TRAFFIC) logger(LOG_ERR, "Sending packet of %d bytes to %s (%s)",
517 packet->len, n->name, n->hostname);
519 if(!n->status.reachable) {
520 ifdebug(TRAFFIC) logger(LOG_INFO, "Node %s (%s) is not reachable",
521 n->name, n->hostname);
525 via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
528 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending packet to %s via %s (%s)",
529 n->name, via->name, n->via->hostname);
531 if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
532 if(!send_tcppacket(via->connection, packet))
533 terminate_connection(via->connection, true);
535 send_udppacket(via, packet);
538 /* Broadcast a packet using the minimum spanning tree */
540 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
544 ifdebug(TRAFFIC) logger(LOG_INFO, "Broadcasting packet of %d bytes from %s (%s)",
545 packet->len, from->name, from->hostname);
548 send_packet(myself, packet);
550 // In TunnelServer mode, do not forward broadcast packets.
551 // The MST might not be valid and create loops.
556 for(node = connection_tree->head; node; node = node->next) {
559 if(c->status.active && c->status.mst && c != from->nexthop->connection)
560 send_packet(c->node, packet);
564 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
568 static time_t last_hard_try = 0;
570 for(node = edge_weight_tree->head; node; node = node->next) {
573 if(sockaddrcmp_noport(from, &e->address)) {
574 if(last_hard_try == now)
582 if(!try_mac(e->to, pkt))
592 void handle_incoming_vpn_data(int sock) {
596 socklen_t fromlen = sizeof(from);
599 pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
602 if(!sockwouldblock(sockerrno))
603 logger(LOG_ERR, "Receiving packet failed: %s", sockstrerror(sockerrno));
607 sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
609 n = lookup_node_udp(&from);
612 n = try_harder(&from, &pkt);
614 update_node_udp(n, &from);
615 else ifdebug(PROTOCOL) {
616 hostname = sockaddr2hostname(&from);
617 logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
625 receive_udppacket(n, &pkt);