2 net_packet.c -- Handles in- and outgoing VPN packets
3 Copyright (C) 1998-2005 Ivo Timmermans,
4 2000-2009 Guus Sliepen <guus@tinc-vpn.org>
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.
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.
16 You should have received a copy of the GNU General Public License along
17 with this program; if not, write to the Free Software Foundation, Inc.,
18 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
26 #include "splay_tree.h"
29 #include "connection.h"
47 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
49 static void send_udppacket(node_t *, vpn_packet_t *);
51 #define MAX_SEQNO 1073741824
53 // mtuprobes == 1..30: initial discovery, send bursts with 1 second interval
54 // mtuprobes == 31: sleep pinginterval seconds
55 // mtuprobes == 32: send 1 burst, sleep pingtimeout second
56 // mtuprobes == 33: no response from other side, restart PMTU discovery process
58 static void send_mtu_probe_handler(int fd, short events, void *data) {
66 if(!n->status.reachable || !n->status.validkey) {
67 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send MTU probe to unreachable or rekeying node %s (%s)", n->name, n->hostname);
72 if(n->mtuprobes > 32) {
73 ifdebug(TRAFFIC) logger(LOG_INFO, "%s (%s) did not respond to UDP ping, restarting PMTU discovery", n->name, n->hostname);
79 if(n->mtuprobes >= 10 && !n->minmtu) {
80 ifdebug(TRAFFIC) logger(LOG_INFO, "No response to MTU probes from %s (%s)", n->name, n->hostname);
85 if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) {
86 if(n->minmtu > n->maxmtu)
87 n->minmtu = n->maxmtu;
89 n->maxmtu = n->minmtu;
91 ifdebug(TRAFFIC) logger(LOG_INFO, "Fixing MTU of %s (%s) to %d after %d probes", n->name, n->hostname, n->mtu, n->mtuprobes);
95 if(n->mtuprobes == 31) {
96 timeout = pinginterval;
98 } else if(n->mtuprobes == 32) {
99 timeout = pingtimeout;
102 for(i = 0; i < 3; i++) {
103 if(n->maxmtu <= n->minmtu)
106 len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
111 memset(packet.data, 0, 14);
112 randomize(packet.data + 14, len - 14);
116 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
118 send_udppacket(n, &packet);
122 event_add(&n->mtuevent, &(struct timeval){timeout, 0});
125 void send_mtu_probe(node_t *n) {
126 if(!timeout_initialized(&n->mtuevent))
127 timeout_set(&n->mtuevent, send_mtu_probe_handler, n);
128 send_mtu_probe_handler(0, 0, n);
131 void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
132 ifdebug(TRAFFIC) logger(LOG_INFO, "Got MTU probe length %d from %s (%s)", packet->len, n->name, n->hostname);
134 if(!packet->data[0]) {
136 send_udppacket(n, packet);
142 if(n->mtuprobes > 30)
147 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
149 lzo_uint lzolen = MAXSIZE;
150 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
152 } else if(level < 10) {
153 unsigned long destlen = MAXSIZE;
154 if(compress2(dest, &destlen, source, len, level) == Z_OK)
159 lzo_uint lzolen = MAXSIZE;
160 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
167 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
169 lzo_uint lzolen = MAXSIZE;
170 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
175 unsigned long destlen = MAXSIZE;
176 if(uncompress(dest, &destlen, source, len) == Z_OK)
187 static void receive_packet(node_t *n, vpn_packet_t *packet) {
188 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Received packet of %d bytes from %s (%s)",
189 packet->len, n->name, n->hostname);
194 static bool try_mac(node_t *n, const vpn_packet_t *inpkt) {
195 if(!digest_active(&n->indigest) || inpkt->len < sizeof inpkt->seqno + digest_length(&n->indigest))
198 return digest_verify(&n->indigest, &inpkt->seqno, inpkt->len - n->indigest.maclength, (const char *)&inpkt->seqno + inpkt->len - n->indigest.maclength);
201 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
202 vpn_packet_t pkt1, pkt2;
203 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
205 vpn_packet_t *outpkt = pkt[0];
209 if(!cipher_active(&n->incipher)) {
210 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet",
211 n->name, n->hostname);
215 /* Check packet length */
217 if(inpkt->len < sizeof inpkt->seqno + digest_length(&n->indigest)) {
218 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got too short packet from %s (%s)",
219 n->name, n->hostname);
223 /* Check the message authentication code */
225 if(digest_active(&n->indigest)) {
226 inpkt->len -= n->indigest.maclength;
227 if(!digest_verify(&n->indigest, &inpkt->seqno, inpkt->len, (const char *)&inpkt->seqno + inpkt->len)) {
228 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got unauthenticated packet from %s (%s)", n->name, n->hostname);
232 /* Decrypt the packet */
234 if(cipher_active(&n->incipher)) {
235 outpkt = pkt[nextpkt++];
238 if(!cipher_decrypt(&n->incipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
239 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Error decrypting packet from %s (%s)", n->name, n->hostname);
243 outpkt->len = outlen;
247 /* Check the sequence number */
249 inpkt->len -= sizeof inpkt->seqno;
250 inpkt->seqno = ntohl(inpkt->seqno);
252 if(inpkt->seqno != n->received_seqno + 1) {
253 if(inpkt->seqno >= n->received_seqno + sizeof n->late * 8) {
254 logger(LOG_WARNING, "Lost %d packets from %s (%s)",
255 inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
257 memset(n->late, 0, sizeof n->late);
258 } else if (inpkt->seqno <= n->received_seqno) {
259 if((n->received_seqno >= sizeof n->late * 8 && inpkt->seqno <= n->received_seqno - sizeof n->late * 8) || !(n->late[(inpkt->seqno / 8) % sizeof n->late] & (1 << inpkt->seqno % 8))) {
260 logger(LOG_WARNING, "Got late or replayed packet from %s (%s), seqno %d, last received %d",
261 n->name, n->hostname, inpkt->seqno, n->received_seqno);
265 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
266 n->late[(i / 8) % sizeof n->late] |= 1 << i % 8;
270 n->late[(inpkt->seqno / 8) % sizeof n->late] &= ~(1 << inpkt->seqno % 8);
272 if(inpkt->seqno > n->received_seqno)
273 n->received_seqno = inpkt->seqno;
275 if(n->received_seqno > MAX_SEQNO)
278 /* Decompress the packet */
280 length_t origlen = inpkt->len;
282 if(n->incompression) {
283 outpkt = pkt[nextpkt++];
285 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
286 ifdebug(TRAFFIC) logger(LOG_ERR, "Error while uncompressing packet from %s (%s)",
287 n->name, n->hostname);
293 origlen -= MTU/64 + 20;
298 if(!inpkt->data[12] && !inpkt->data[13])
299 mtu_probe_h(n, inpkt, origlen);
301 receive_packet(n, inpkt);
304 void receive_tcppacket(connection_t *c, char *buffer, int len) {
308 if(c->options & OPTION_TCPONLY)
311 outpkt.priority = -1;
312 memcpy(outpkt.data, buffer, len);
314 receive_packet(c->node, &outpkt);
317 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
318 vpn_packet_t pkt1, pkt2;
319 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
320 vpn_packet_t *inpkt = origpkt;
322 vpn_packet_t *outpkt;
325 static int priority = 0;
329 if(!n->status.reachable) {
330 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send UDP packet to unreachable node %s (%s)", n->name, n->hostname);
334 /* Make sure we have a valid key */
336 if(!n->status.validkey) {
337 ifdebug(TRAFFIC) logger(LOG_INFO,
338 "No valid key known yet for %s (%s), forwarding via TCP",
339 n->name, n->hostname);
341 if(!n->status.waitingforkey)
344 n->status.waitingforkey = true;
346 send_tcppacket(n->nexthop->connection, origpkt);
351 if(n->options & OPTION_PMTU_DISCOVERY && inpkt->len > n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
352 ifdebug(TRAFFIC) logger(LOG_INFO,
353 "Packet for %s (%s) larger than minimum MTU, forwarding via %s",
354 n->name, n->hostname, n != n->nexthop ? n->nexthop->name : "TCP");
357 send_packet(n->nexthop, origpkt);
359 send_tcppacket(n->nexthop->connection, origpkt);
364 origlen = inpkt->len;
365 origpriority = inpkt->priority;
367 /* Compress the packet */
369 if(n->outcompression) {
370 outpkt = pkt[nextpkt++];
372 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
373 ifdebug(TRAFFIC) logger(LOG_ERR, "Error while compressing packet to %s (%s)",
374 n->name, n->hostname);
381 /* Add sequence number */
383 inpkt->seqno = htonl(++(n->sent_seqno));
384 inpkt->len += sizeof inpkt->seqno;
386 /* Encrypt the packet */
388 if(cipher_active(&n->outcipher)) {
389 outpkt = pkt[nextpkt++];
392 if(!cipher_encrypt(&n->outcipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
393 ifdebug(TRAFFIC) logger(LOG_ERR, "Error while encrypting packet to %s (%s)", n->name, n->hostname);
397 outpkt->len = outlen;
401 /* Add the message authentication code */
403 if(digest_active(&n->outdigest)) {
404 digest_create(&n->outdigest, &inpkt->seqno, inpkt->len, (char *)&inpkt->seqno + inpkt->len);
405 inpkt->len += digest_length(&n->outdigest);
408 /* Determine which socket we have to use */
410 for(sock = 0; sock < listen_sockets; sock++)
411 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
414 if(sock >= listen_sockets)
415 sock = 0; /* If none is available, just use the first and hope for the best. */
417 /* Send the packet */
419 #if defined(SOL_IP) && defined(IP_TOS)
420 if(priorityinheritance && origpriority != priority
421 && listen_socket[sock].sa.sa.sa_family == AF_INET) {
422 priority = origpriority;
423 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting outgoing packet priority to %d", priority);
424 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof priority)) /* SO_PRIORITY doesn't seem to work */
425 logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
429 if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa)) < 0 && !sockwouldblock(sockerrno)) {
430 if(sockmsgsize(sockerrno)) {
431 if(n->maxmtu >= origlen)
432 n->maxmtu = origlen - 1;
433 if(n->mtu >= origlen)
434 n->mtu = origlen - 1;
436 logger(LOG_ERR, "Error sending packet to %s (%s): %s", n->name, n->hostname, sockstrerror(sockerrno));
440 origpkt->len = origlen;
444 send a packet to the given vpn ip.
446 void send_packet(const node_t *n, vpn_packet_t *packet) {
451 memcpy(packet->data, mymac.x, ETH_ALEN);
452 write_packet(packet);
456 ifdebug(TRAFFIC) logger(LOG_ERR, "Sending packet of %d bytes to %s (%s)",
457 packet->len, n->name, n->hostname);
459 if(!n->status.reachable) {
460 ifdebug(TRAFFIC) logger(LOG_INFO, "Node %s (%s) is not reachable",
461 n->name, n->hostname);
465 via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
468 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending packet to %s via %s (%s)",
469 n->name, via->name, n->via->hostname);
471 if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
472 if(!send_tcppacket(via->connection, packet))
473 terminate_connection(via->connection, true);
475 send_udppacket(via, packet);
478 /* Broadcast a packet using the minimum spanning tree */
480 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
484 ifdebug(TRAFFIC) logger(LOG_INFO, "Broadcasting packet of %d bytes from %s (%s)",
485 packet->len, from->name, from->hostname);
488 send_packet(myself, packet);
490 // In TunnelServer mode, do not forward broadcast packets.
491 // The MST might not be valid and create loops.
496 for(node = connection_tree->head; node; node = node->next) {
499 if(c->status.active && c->status.mst && c != from->nexthop->connection)
500 send_packet(c->node, packet);
504 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
506 node_t *n, *found = NULL;
507 static time_t last_hard_try = 0;
508 time_t now = time(NULL);
510 if(last_hard_try == now)
515 for(node = node_tree->head; node; node = node->next) {
518 if(n == myself || !n->status.reachable || !digest_active(&n->indigest))
521 if(try_mac(n, pkt)) {
530 void handle_incoming_vpn_data(int sock, short events, void *data) {
534 socklen_t fromlen = sizeof from;
538 len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
540 if(len <= 0 || len > MAXSIZE) {
541 if(!sockwouldblock(sockerrno))
542 logger(LOG_ERR, "Receiving packet failed: %s", sockstrerror(sockerrno));
548 sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
550 n = lookup_node_udp(&from);
553 n = try_harder(&from, &pkt);
555 update_node_udp(n, &from);
556 else ifdebug(PROTOCOL) {
557 hostname = sockaddr2hostname(&from);
558 logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
566 receive_udppacket(n, &pkt);
569 void handle_device_data(int sock, short events, void *data) {
572 if(read_packet(&packet))
573 route(myself, &packet);