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>
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License along
18 with this program; if not, write to the Free Software Foundation, Inc.,
19 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
24 #include <openssl/rand.h>
25 #include <openssl/err.h>
26 #include <openssl/evp.h>
27 #include <openssl/pem.h>
28 #include <openssl/hmac.h>
40 #include "connection.h"
58 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
61 static void send_udppacket(node_t *, vpn_packet_t *);
63 #define MAX_SEQNO 1073741824
65 // mtuprobes == 1..30: initial discovery, send bursts with 1 second interval
66 // mtuprobes == 31: sleep pinginterval seconds
67 // mtuprobes == 32: send 1 burst, sleep pingtimeout second
68 // mtuprobes == 33: no response from other side, restart PMTU discovery process
70 void send_mtu_probe(node_t *n) {
78 if(!n->status.reachable || !n->status.validkey) {
79 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send MTU probe to unreachable or rekeying node %s (%s)", n->name, n->hostname);
84 if(n->mtuprobes > 32) {
85 ifdebug(TRAFFIC) logger(LOG_INFO, "%s (%s) did not respond to UDP ping, restarting PMTU discovery", n->name, n->hostname);
91 if(n->mtuprobes >= 10 && !n->minmtu) {
92 ifdebug(TRAFFIC) logger(LOG_INFO, "No response to MTU probes from %s (%s)", n->name, n->hostname);
97 if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) {
98 if(n->minmtu > n->maxmtu)
99 n->minmtu = n->maxmtu;
101 n->maxmtu = n->minmtu;
103 ifdebug(TRAFFIC) logger(LOG_INFO, "Fixing MTU of %s (%s) to %d after %d probes", n->name, n->hostname, n->mtu, n->mtuprobes);
107 if(n->mtuprobes == 31) {
108 timeout = pinginterval;
110 } else if(n->mtuprobes == 32) {
111 timeout = pingtimeout;
114 for(i = 0; i < 3; i++) {
115 if(n->maxmtu <= n->minmtu)
118 len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
123 memset(packet.data, 0, 14);
124 RAND_pseudo_bytes(packet.data + 14, len - 14);
128 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
130 send_udppacket(n, &packet);
134 n->mtuevent = new_event();
135 n->mtuevent->handler = (event_handler_t)send_mtu_probe;
136 n->mtuevent->data = n;
137 n->mtuevent->time = now + timeout;
138 event_add(n->mtuevent);
141 void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
142 ifdebug(TRAFFIC) logger(LOG_INFO, "Got MTU probe length %d from %s (%s)", packet->len, n->name, n->hostname);
144 if(!packet->data[0]) {
146 send_udppacket(n, packet);
152 if(n->mtuprobes > 30)
157 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
159 memcpy(dest, source, len);
161 } else if(level == 10) {
163 lzo_uint lzolen = MAXSIZE;
164 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
169 } else if(level < 10) {
171 unsigned long destlen = MAXSIZE;
172 if(compress2(dest, &destlen, source, len, level) == Z_OK)
179 lzo_uint lzolen = MAXSIZE;
180 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
190 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
192 memcpy(dest, source, len);
194 } else if(level > 9) {
196 lzo_uint lzolen = MAXSIZE;
197 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
205 unsigned long destlen = MAXSIZE;
206 if(uncompress(dest, &destlen, source, len) == Z_OK)
218 static void receive_packet(node_t *n, vpn_packet_t *packet) {
219 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Received packet of %d bytes from %s (%s)",
220 packet->len, n->name, n->hostname);
225 static bool try_mac(const node_t *n, const vpn_packet_t *inpkt) {
226 unsigned char hmac[EVP_MAX_MD_SIZE];
228 if(!n->indigest || !n->inmaclength || !n->inkey || inpkt->len < sizeof inpkt->seqno + n->inmaclength)
231 HMAC(n->indigest, n->inkey, n->inkeylength, (unsigned char *) &inpkt->seqno, inpkt->len - n->inmaclength, (unsigned char *)hmac, NULL);
233 return !memcmp(hmac, (char *) &inpkt->seqno + inpkt->len - n->inmaclength, n->inmaclength);
236 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
237 vpn_packet_t pkt1, pkt2;
238 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
240 vpn_packet_t *outpkt = pkt[0];
242 unsigned char hmac[EVP_MAX_MD_SIZE];
246 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet",
247 n->name, n->hostname);
251 /* Check packet length */
253 if(inpkt->len < sizeof(inpkt->seqno) + n->inmaclength) {
254 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got too short packet from %s (%s)",
255 n->name, n->hostname);
259 /* Check the message authentication code */
261 if(n->indigest && n->inmaclength) {
262 inpkt->len -= n->inmaclength;
263 HMAC(n->indigest, n->inkey, n->inkeylength,
264 (unsigned char *) &inpkt->seqno, inpkt->len, (unsigned char *)hmac, NULL);
266 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, n->inmaclength)) {
267 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got unauthenticated packet from %s (%s)",
268 n->name, n->hostname);
273 /* Decrypt the packet */
276 outpkt = pkt[nextpkt++];
278 if(!EVP_DecryptInit_ex(&n->inctx, NULL, NULL, NULL, NULL)
279 || !EVP_DecryptUpdate(&n->inctx, (unsigned char *) &outpkt->seqno, &outlen,
280 (unsigned char *) &inpkt->seqno, inpkt->len)
281 || !EVP_DecryptFinal_ex(&n->inctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
282 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Error decrypting packet from %s (%s): %s",
283 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
287 outpkt->len = outlen + outpad;
291 /* Check the sequence number */
293 inpkt->len -= sizeof(inpkt->seqno);
294 inpkt->seqno = ntohl(inpkt->seqno);
296 if(inpkt->seqno != n->received_seqno + 1) {
297 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
298 logger(LOG_WARNING, "Lost %d packets from %s (%s)",
299 inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
301 memset(n->late, 0, sizeof(n->late));
302 } else if (inpkt->seqno <= n->received_seqno) {
303 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))) {
304 logger(LOG_WARNING, "Got late or replayed packet from %s (%s), seqno %d, last received %d",
305 n->name, n->hostname, inpkt->seqno, n->received_seqno);
309 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
310 n->late[(i / 8) % sizeof(n->late)] |= 1 << i % 8;
314 n->late[(inpkt->seqno / 8) % sizeof(n->late)] &= ~(1 << inpkt->seqno % 8);
316 if(inpkt->seqno > n->received_seqno)
317 n->received_seqno = inpkt->seqno;
319 if(n->received_seqno > MAX_SEQNO)
322 /* Decompress the packet */
324 length_t origlen = inpkt->len;
326 if(n->incompression) {
327 outpkt = pkt[nextpkt++];
329 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
330 ifdebug(TRAFFIC) logger(LOG_ERR, "Error while uncompressing packet from %s (%s)",
331 n->name, n->hostname);
337 origlen -= MTU/64 + 20;
342 if(!inpkt->data[12] && !inpkt->data[13])
343 mtu_probe_h(n, inpkt, origlen);
345 receive_packet(n, inpkt);
348 void receive_tcppacket(connection_t *c, char *buffer, int len) {
352 if(c->options & OPTION_TCPONLY)
355 outpkt.priority = -1;
356 memcpy(outpkt.data, buffer, len);
358 receive_packet(c->node, &outpkt);
361 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
362 vpn_packet_t pkt1, pkt2;
363 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
364 vpn_packet_t *inpkt = origpkt;
366 vpn_packet_t *outpkt;
369 #if defined(SOL_IP) && defined(IP_TOS)
370 static int priority = 0;
375 if(!n->status.reachable) {
376 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send UDP packet to unreachable node %s (%s)", n->name, n->hostname);
380 /* Make sure we have a valid key */
382 if(!n->status.validkey) {
383 ifdebug(TRAFFIC) logger(LOG_INFO,
384 "No valid key known yet for %s (%s), forwarding via TCP",
385 n->name, n->hostname);
387 if(n->last_req_key + 10 < now) {
389 n->last_req_key = now;
392 send_tcppacket(n->nexthop->connection, origpkt);
397 if(n->options & OPTION_PMTU_DISCOVERY && inpkt->len > n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
398 ifdebug(TRAFFIC) logger(LOG_INFO,
399 "Packet for %s (%s) larger than minimum MTU, forwarding via %s",
400 n->name, n->hostname, n != n->nexthop ? n->nexthop->name : "TCP");
403 send_packet(n->nexthop, origpkt);
405 send_tcppacket(n->nexthop->connection, origpkt);
410 origlen = inpkt->len;
411 origpriority = inpkt->priority;
413 /* Compress the packet */
415 if(n->outcompression) {
416 outpkt = pkt[nextpkt++];
418 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
419 ifdebug(TRAFFIC) logger(LOG_ERR, "Error while compressing packet to %s (%s)",
420 n->name, n->hostname);
427 /* Add sequence number */
429 inpkt->seqno = htonl(++(n->sent_seqno));
430 inpkt->len += sizeof(inpkt->seqno);
432 /* Encrypt the packet */
435 outpkt = pkt[nextpkt++];
437 if(!EVP_EncryptInit_ex(&n->outctx, NULL, NULL, NULL, NULL)
438 || !EVP_EncryptUpdate(&n->outctx, (unsigned char *) &outpkt->seqno, &outlen,
439 (unsigned char *) &inpkt->seqno, inpkt->len)
440 || !EVP_EncryptFinal_ex(&n->outctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
441 ifdebug(TRAFFIC) logger(LOG_ERR, "Error while encrypting packet to %s (%s): %s",
442 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
446 outpkt->len = outlen + outpad;
450 /* Add the message authentication code */
452 if(n->outdigest && n->outmaclength) {
453 HMAC(n->outdigest, n->outkey, n->outkeylength, (unsigned char *) &inpkt->seqno,
454 inpkt->len, (unsigned char *) &inpkt->seqno + inpkt->len, NULL);
455 inpkt->len += n->outmaclength;
458 /* Determine which socket we have to use */
460 for(sock = 0; sock < listen_sockets; sock++)
461 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
464 if(sock >= listen_sockets)
465 sock = 0; /* If none is available, just use the first and hope for the best. */
467 /* Send the packet */
469 #if defined(SOL_IP) && defined(IP_TOS)
470 if(priorityinheritance && origpriority != priority
471 && listen_socket[sock].sa.sa.sa_family == AF_INET) {
472 priority = origpriority;
473 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting outgoing packet priority to %d", priority);
474 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */
475 logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
479 if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa)) < 0 && !sockwouldblock(sockerrno)) {
480 if(sockmsgsize(sockerrno)) {
481 if(n->maxmtu >= origlen)
482 n->maxmtu = origlen - 1;
483 if(n->mtu >= origlen)
484 n->mtu = origlen - 1;
486 logger(LOG_ERR, "Error sending packet to %s (%s): %s", n->name, n->hostname, sockstrerror(sockerrno));
490 origpkt->len = origlen;
494 send a packet to the given vpn ip.
496 void send_packet(const node_t *n, vpn_packet_t *packet) {
501 memcpy(packet->data, mymac.x, ETH_ALEN);
502 write_packet(packet);
506 ifdebug(TRAFFIC) logger(LOG_ERR, "Sending packet of %d bytes to %s (%s)",
507 packet->len, n->name, n->hostname);
509 if(!n->status.reachable) {
510 ifdebug(TRAFFIC) logger(LOG_INFO, "Node %s (%s) is not reachable",
511 n->name, n->hostname);
515 via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
518 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending packet to %s via %s (%s)",
519 n->name, via->name, n->via->hostname);
521 if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
522 if(!send_tcppacket(via->connection, packet))
523 terminate_connection(via->connection, true);
525 send_udppacket(via, packet);
528 /* Broadcast a packet using the minimum spanning tree */
530 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
534 ifdebug(TRAFFIC) logger(LOG_INFO, "Broadcasting packet of %d bytes from %s (%s)",
535 packet->len, from->name, from->hostname);
538 send_packet(myself, packet);
540 // In TunnelServer mode, do not forward broadcast packets.
541 // The MST might not be valid and create loops.
546 for(node = connection_tree->head; node; node = node->next) {
549 if(c->status.active && c->status.mst && c != from->nexthop->connection)
550 send_packet(c->node, packet);
554 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
558 static time_t last_hard_try = 0;
560 for(node = edge_weight_tree->head; node; node = node->next) {
563 if(sockaddrcmp_noport(from, &e->address)) {
564 if(last_hard_try == now)
572 if(!try_mac(e->to, pkt))
582 void handle_incoming_vpn_data(int sock) {
586 socklen_t fromlen = sizeof(from);
589 pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
592 if(!sockwouldblock(sockerrno))
593 logger(LOG_ERR, "Receiving packet failed: %s", sockstrerror(sockerrno));
597 sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
599 n = lookup_node_udp(&from);
602 n = try_harder(&from, &pkt);
604 update_node_udp(n, &from);
605 else ifdebug(PROTOCOL) {
606 hostname = sockaddr2hostname(&from);
607 logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
615 receive_udppacket(n, &pkt);