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.
23 #include <openssl/rand.h>
24 #include <openssl/err.h>
25 #include <openssl/evp.h>
26 #include <openssl/pem.h>
27 #include <openssl/hmac.h>
34 #include "connection.h"
51 #define EMSGSIZE WSAEMSGSIZE
52 #define EAGAIN WSATRY_AGAIN
53 #define EINTR WSAEINTR
54 #define sockstrerror(x) winerror(x)
55 #define sockerrno WSAGetLastError()
57 #define sockstrerror(x) strerror(x)
58 #define sockerrno errno
63 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
65 static void send_udppacket(node_t *, vpn_packet_t *);
67 #define MAX_SEQNO 1073741824
69 // mtuprobes == 1..30: initial discovery, send bursts with 1 second interval
70 // mtuprobes == 31: sleep pinginterval seconds
71 // mtuprobes == 32: send 1 burst, sleep pingtimeout second
72 // mtuprobes == 33: no response from other side, restart PMTU discovery process
74 void send_mtu_probe(node_t *n) {
82 if(!n->status.reachable || !n->status.validkey) {
83 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send MTU probe to unreachable or rekeying node %s (%s)", n->name, n->hostname);
88 if(n->mtuprobes > 32) {
89 ifdebug(TRAFFIC) logger(LOG_INFO, "%s (%s) did not respond to UDP ping, restarting PMTU discovery", n->name, n->hostname);
95 if(n->mtuprobes >= 10 && !n->minmtu) {
96 ifdebug(TRAFFIC) logger(LOG_INFO, "No response to MTU probes from %s (%s)", n->name, n->hostname);
101 if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) {
102 if(n->minmtu > n->maxmtu)
103 n->minmtu = n->maxmtu;
105 n->maxmtu = n->minmtu;
107 ifdebug(TRAFFIC) logger(LOG_INFO, "Fixing MTU of %s (%s) to %d after %d probes", n->name, n->hostname, n->mtu, n->mtuprobes);
111 if(n->mtuprobes == 31) {
112 timeout = pinginterval;
114 } else if(n->mtuprobes == 32) {
115 timeout = pingtimeout;
118 for(i = 0; i < 3; i++) {
119 if(n->maxmtu <= n->minmtu)
122 len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
127 memset(packet.data, 0, 14);
128 RAND_pseudo_bytes(packet.data + 14, len - 14);
132 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
134 send_udppacket(n, &packet);
138 n->mtuevent = new_event();
139 n->mtuevent->handler = (event_handler_t)send_mtu_probe;
140 n->mtuevent->data = n;
141 n->mtuevent->time = now + timeout;
142 event_add(n->mtuevent);
145 void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
146 ifdebug(TRAFFIC) logger(LOG_INFO, "Got MTU probe length %d from %s (%s)", packet->len, n->name, n->hostname);
148 if(!packet->data[0]) {
150 send_udppacket(n, packet);
156 if(n->mtuprobes > 30)
161 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
163 lzo_uint lzolen = MAXSIZE;
164 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
166 } else if(level < 10) {
167 unsigned long destlen = MAXSIZE;
168 if(compress2(dest, &destlen, source, len, level) == Z_OK)
173 lzo_uint lzolen = MAXSIZE;
174 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
181 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
183 lzo_uint lzolen = MAXSIZE;
184 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
189 unsigned long destlen = MAXSIZE;
190 if(uncompress(dest, &destlen, source, len) == Z_OK)
201 static void receive_packet(node_t *n, vpn_packet_t *packet) {
202 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Received packet of %d bytes from %s (%s)",
203 packet->len, n->name, n->hostname);
208 static bool try_mac(const node_t *n, const vpn_packet_t *inpkt) {
209 unsigned char hmac[EVP_MAX_MD_SIZE];
211 if(!n->indigest || !n->inmaclength || !n->inkey || inpkt->len < sizeof inpkt->seqno + n->inmaclength)
214 HMAC(n->indigest, n->inkey, n->inkeylength, (unsigned char *) &inpkt->seqno, inpkt->len - n->inmaclength, (unsigned char *)hmac, NULL);
216 return !memcmp(hmac, (char *) &inpkt->seqno + inpkt->len - n->inmaclength, n->inmaclength);
219 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
220 vpn_packet_t pkt1, pkt2;
221 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
223 vpn_packet_t *outpkt = pkt[0];
225 unsigned char hmac[EVP_MAX_MD_SIZE];
229 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet",
230 n->name, n->hostname);
234 /* Check packet length */
236 if(inpkt->len < sizeof(inpkt->seqno) + n->inmaclength) {
237 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got too short packet from %s (%s)",
238 n->name, n->hostname);
242 /* Check the message authentication code */
244 if(n->indigest && n->inmaclength) {
245 inpkt->len -= n->inmaclength;
246 HMAC(n->indigest, n->inkey, n->inkeylength,
247 (unsigned char *) &inpkt->seqno, inpkt->len, (unsigned char *)hmac, NULL);
249 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, n->inmaclength)) {
250 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got unauthenticated packet from %s (%s)",
251 n->name, n->hostname);
256 /* Decrypt the packet */
259 outpkt = pkt[nextpkt++];
261 if(!EVP_DecryptInit_ex(&n->inctx, NULL, NULL, NULL, NULL)
262 || !EVP_DecryptUpdate(&n->inctx, (unsigned char *) &outpkt->seqno, &outlen,
263 (unsigned char *) &inpkt->seqno, inpkt->len)
264 || !EVP_DecryptFinal_ex(&n->inctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
265 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Error decrypting packet from %s (%s): %s",
266 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
270 outpkt->len = outlen + outpad;
274 /* Check the sequence number */
276 inpkt->len -= sizeof(inpkt->seqno);
277 inpkt->seqno = ntohl(inpkt->seqno);
279 if(inpkt->seqno != n->received_seqno + 1) {
280 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
281 logger(LOG_WARNING, "Lost %d packets from %s (%s)",
282 inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
284 memset(n->late, 0, sizeof(n->late));
285 } else if (inpkt->seqno <= n->received_seqno) {
286 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))) {
287 logger(LOG_WARNING, "Got late or replayed packet from %s (%s), seqno %d, last received %d",
288 n->name, n->hostname, inpkt->seqno, n->received_seqno);
292 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
293 n->late[(i / 8) % sizeof(n->late)] |= 1 << i % 8;
297 n->late[(inpkt->seqno / 8) % sizeof(n->late)] &= ~(1 << inpkt->seqno % 8);
299 if(inpkt->seqno > n->received_seqno)
300 n->received_seqno = inpkt->seqno;
302 if(n->received_seqno > MAX_SEQNO)
305 /* Decompress the packet */
307 length_t origlen = inpkt->len;
309 if(n->incompression) {
310 outpkt = pkt[nextpkt++];
312 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
313 ifdebug(TRAFFIC) logger(LOG_ERR, "Error while uncompressing packet from %s (%s)",
314 n->name, n->hostname);
320 origlen -= MTU/64 + 20;
325 if(!inpkt->data[12] && !inpkt->data[13])
326 mtu_probe_h(n, inpkt, origlen);
328 receive_packet(n, inpkt);
331 void receive_tcppacket(connection_t *c, char *buffer, int len) {
335 if(c->options & OPTION_TCPONLY)
338 outpkt.priority = -1;
339 memcpy(outpkt.data, buffer, len);
341 receive_packet(c->node, &outpkt);
344 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
345 vpn_packet_t pkt1, pkt2;
346 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
347 vpn_packet_t *inpkt = origpkt;
349 vpn_packet_t *outpkt;
352 static int priority = 0;
356 if(!n->status.reachable) {
357 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send UDP packet to unreachable node %s (%s)", n->name, n->hostname);
361 /* Make sure we have a valid key */
363 if(!n->status.validkey) {
364 ifdebug(TRAFFIC) logger(LOG_INFO,
365 "No valid key known yet for %s (%s), forwarding via TCP",
366 n->name, n->hostname);
368 if(!n->status.waitingforkey)
371 n->status.waitingforkey = true;
373 send_tcppacket(n->nexthop->connection, origpkt);
378 if(n->options & OPTION_PMTU_DISCOVERY && inpkt->len > n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
379 ifdebug(TRAFFIC) logger(LOG_INFO,
380 "Packet for %s (%s) larger than minimum MTU, forwarding via %s",
381 n->name, n->hostname, n != n->nexthop ? n->nexthop->name : "TCP");
384 send_packet(n->nexthop, origpkt);
386 send_tcppacket(n->nexthop->connection, origpkt);
391 origlen = inpkt->len;
392 origpriority = inpkt->priority;
394 /* Compress the packet */
396 if(n->outcompression) {
397 outpkt = pkt[nextpkt++];
399 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
400 ifdebug(TRAFFIC) logger(LOG_ERR, "Error while compressing packet to %s (%s)",
401 n->name, n->hostname);
408 /* Add sequence number */
410 inpkt->seqno = htonl(++(n->sent_seqno));
411 inpkt->len += sizeof(inpkt->seqno);
413 /* Encrypt the packet */
416 outpkt = pkt[nextpkt++];
418 if(!EVP_EncryptInit_ex(&n->outctx, NULL, NULL, NULL, NULL)
419 || !EVP_EncryptUpdate(&n->outctx, (unsigned char *) &outpkt->seqno, &outlen,
420 (unsigned char *) &inpkt->seqno, inpkt->len)
421 || !EVP_EncryptFinal_ex(&n->outctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
422 ifdebug(TRAFFIC) logger(LOG_ERR, "Error while encrypting packet to %s (%s): %s",
423 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
427 outpkt->len = outlen + outpad;
431 /* Add the message authentication code */
433 if(n->outdigest && n->outmaclength) {
434 HMAC(n->outdigest, n->outkey, n->outkeylength, (unsigned char *) &inpkt->seqno,
435 inpkt->len, (unsigned char *) &inpkt->seqno + inpkt->len, NULL);
436 inpkt->len += n->outmaclength;
439 /* Determine which socket we have to use */
441 for(sock = 0; sock < listen_sockets; sock++)
442 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
445 if(sock >= listen_sockets)
446 sock = 0; /* If none is available, just use the first and hope for the best. */
448 /* Send the packet */
450 #if defined(SOL_IP) && defined(IP_TOS)
451 if(priorityinheritance && origpriority != priority
452 && listen_socket[sock].sa.sa.sa_family == AF_INET) {
453 priority = origpriority;
454 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting outgoing packet priority to %d", priority);
455 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */
456 logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
460 if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
461 if(sockerrno == EMSGSIZE) {
462 if(n->maxmtu >= origlen)
463 n->maxmtu = origlen - 1;
464 if(n->mtu >= origlen)
465 n->mtu = origlen - 1;
467 logger(LOG_ERR, "Error sending packet to %s (%s): %s", n->name, n->hostname, sockstrerror(sockerrno));
471 origpkt->len = origlen;
475 send a packet to the given vpn ip.
477 void send_packet(const node_t *n, vpn_packet_t *packet) {
482 memcpy(packet->data, mymac.x, ETH_ALEN);
483 write_packet(packet);
487 ifdebug(TRAFFIC) logger(LOG_ERR, "Sending packet of %d bytes to %s (%s)",
488 packet->len, n->name, n->hostname);
490 if(!n->status.reachable) {
491 ifdebug(TRAFFIC) logger(LOG_INFO, "Node %s (%s) is not reachable",
492 n->name, n->hostname);
496 via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
499 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending packet to %s via %s (%s)",
500 n->name, via->name, n->via->hostname);
502 if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
503 if(!send_tcppacket(via->connection, packet))
504 terminate_connection(via->connection, true);
506 send_udppacket(via, packet);
509 /* Broadcast a packet using the minimum spanning tree */
511 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
515 ifdebug(TRAFFIC) logger(LOG_INFO, "Broadcasting packet of %d bytes from %s (%s)",
516 packet->len, from->name, from->hostname);
519 send_packet(myself, packet);
521 // In TunnelServer mode, do not forward broadcast packets.
522 // The MST might not be valid and create loops.
527 for(node = connection_tree->head; node; node = node->next) {
530 if(c->status.active && c->status.mst && c != from->nexthop->connection)
531 send_packet(c->node, packet);
535 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
539 static time_t last_hard_try = 0;
541 for(node = edge_weight_tree->head; node; node = node->next) {
544 if(sockaddrcmp_noport(from, &e->address)) {
545 if(last_hard_try == now)
553 if(!try_mac(e->to, pkt))
563 void handle_incoming_vpn_data(int sock) {
567 socklen_t fromlen = sizeof(from);
570 pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
573 if(sockerrno != EAGAIN && sockerrno != EINTR)
574 logger(LOG_ERR, "Receiving packet failed: %s", sockstrerror(sockerrno));
578 sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
580 n = lookup_node_udp(&from);
583 n = try_harder(&from, &pkt);
585 update_node_udp(n, &from);
586 else ifdebug(PROTOCOL) {
587 hostname = sockaddr2hostname(&from);
588 logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
596 receive_udppacket(n, &pkt);