2 net_packet.c -- Handles in- and outgoing VPN packets
3 Copyright (C) 1998-2005 Ivo Timmermans,
4 2000-2006 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
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, 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>
32 #ifdef HAVE_LZO_LZO1X_H
33 #include <lzo/lzo1x.h>
41 #include "connection.h"
57 #define EMSGSIZE WSAEMSGSIZE
62 EVP_CIPHER_CTX packet_ctx;
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 void send_mtu_probe(node_t *n)
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);
84 for(i = 0; i < 3; i++) {
85 if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) {
87 ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
91 len = n->minmtu + 1 + random() % (n->maxmtu - n->minmtu);
95 memset(packet.data, 0, 14);
96 RAND_pseudo_bytes(packet.data + 14, len - 14);
99 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
101 send_udppacket(n, &packet);
104 n->mtuevent = xmalloc(sizeof(*n->mtuevent));
105 n->mtuevent->handler = (event_handler_t)send_mtu_probe;
106 n->mtuevent->data = n;
107 n->mtuevent->time = now + 1;
108 event_add(n->mtuevent);
111 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
112 ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
114 if(!packet->data[0]) {
116 send_packet(n, packet);
118 if(n->minmtu < packet->len)
119 n->minmtu = packet->len;
123 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
126 lzo_uint lzolen = MAXSIZE;
127 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
129 } else if(level < 10) {
130 unsigned long destlen = MAXSIZE;
131 if(compress2(dest, &destlen, source, len, level) == Z_OK)
136 lzo_uint lzolen = MAXSIZE;
137 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
144 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
147 lzo_uint lzolen = MAXSIZE;
148 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
153 unsigned long destlen = MAXSIZE;
154 if(uncompress(dest, &destlen, source, len) == Z_OK)
165 static void receive_packet(node_t *n, vpn_packet_t *packet)
169 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
170 packet->len, n->name, n->hostname);
175 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
177 vpn_packet_t pkt1, pkt2;
178 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
180 vpn_packet_t *outpkt = pkt[0];
182 unsigned char hmac[EVP_MAX_MD_SIZE];
187 /* Check packet length */
189 if(inpkt->len < sizeof(inpkt->seqno) + myself->maclength) {
190 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
191 n->name, n->hostname);
195 /* Check the message authentication code */
197 if(myself->digest && myself->maclength) {
198 inpkt->len -= myself->maclength;
199 HMAC(myself->digest, myself->key, myself->keylength,
200 (unsigned char *) &inpkt->seqno, inpkt->len, (unsigned char *)hmac, NULL);
202 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
203 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
204 n->name, n->hostname);
209 /* Decrypt the packet */
212 outpkt = pkt[nextpkt++];
214 if(!EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL)
215 || !EVP_DecryptUpdate(&packet_ctx, (unsigned char *) &outpkt->seqno, &outlen,
216 (unsigned char *) &inpkt->seqno, inpkt->len)
217 || !EVP_DecryptFinal_ex(&packet_ctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
218 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
219 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
223 outpkt->len = outlen + outpad;
227 /* Check the sequence number */
229 inpkt->len -= sizeof(inpkt->seqno);
230 inpkt->seqno = ntohl(inpkt->seqno);
232 if(inpkt->seqno != n->received_seqno + 1) {
233 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
234 logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
235 inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
237 memset(n->late, 0, sizeof(n->late));
238 } else if (inpkt->seqno <= n->received_seqno) {
239 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))) {
240 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
241 n->name, n->hostname, inpkt->seqno, n->received_seqno);
245 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
246 n->late[(i / 8) % sizeof(n->late)] |= 1 << i % 8;
250 n->late[(inpkt->seqno / 8) % sizeof(n->late)] &= ~(1 << inpkt->seqno % 8);
252 if(inpkt->seqno > n->received_seqno)
253 n->received_seqno = inpkt->seqno;
255 if(n->received_seqno > MAX_SEQNO)
258 /* Decompress the packet */
260 if(myself->compression) {
261 outpkt = pkt[nextpkt++];
263 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
264 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
265 n->name, n->hostname);
273 n->connection->last_ping_time = now;
275 if(!inpkt->data[12] && !inpkt->data[13])
276 mtu_probe_h(n, inpkt);
278 receive_packet(n, inpkt);
281 void receive_tcppacket(connection_t *c, char *buffer, int len)
288 memcpy(outpkt.data, buffer, len);
290 receive_packet(c->node, &outpkt);
293 static void send_udppacket(node_t *n, vpn_packet_t *origpkt)
295 vpn_packet_t pkt1, pkt2;
296 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
297 vpn_packet_t *inpkt = origpkt;
299 vpn_packet_t *outpkt;
303 static int priority = 0;
309 /* Make sure we have a valid key */
311 if(!n->status.validkey) {
312 ifdebug(TRAFFIC) logger(LOG_INFO,
313 _("No valid key known yet for %s (%s), queueing packet"),
314 n->name, n->hostname);
316 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
318 *(copy = xmalloc(sizeof(*copy))) = *inpkt;
320 list_insert_tail(n->queue, copy);
322 if(n->queue->count > MAXQUEUELENGTH)
323 list_delete_head(n->queue);
325 if(!n->status.waitingforkey)
326 send_req_key(n->nexthop->connection, myself, n);
328 n->status.waitingforkey = true;
333 origlen = inpkt->len;
334 origpriority = inpkt->priority;
336 /* Compress the packet */
339 outpkt = pkt[nextpkt++];
341 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
342 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
343 n->name, n->hostname);
350 /* Add sequence number */
352 inpkt->seqno = htonl(++(n->sent_seqno));
353 inpkt->len += sizeof(inpkt->seqno);
355 /* Encrypt the packet */
358 outpkt = pkt[nextpkt++];
360 if(!EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL)
361 || !EVP_EncryptUpdate(&n->packet_ctx, (unsigned char *) &outpkt->seqno, &outlen,
362 (unsigned char *) &inpkt->seqno, inpkt->len)
363 || !EVP_EncryptFinal_ex(&n->packet_ctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
364 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
365 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
369 outpkt->len = outlen + outpad;
373 /* Add the message authentication code */
375 if(n->digest && n->maclength) {
376 HMAC(n->digest, n->key, n->keylength, (unsigned char *) &inpkt->seqno,
377 inpkt->len, (unsigned char *) &inpkt->seqno + inpkt->len, NULL);
378 inpkt->len += n->maclength;
381 /* Determine which socket we have to use */
383 for(sock = 0; sock < listen_sockets; sock++)
384 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
387 if(sock >= listen_sockets)
388 sock = 0; /* If none is available, just use the first and hope for the best. */
390 /* Send the packet */
392 #if defined(SOL_IP) && defined(IP_TOS)
393 if(priorityinheritance && origpriority != priority
394 && listen_socket[sock].sa.sa.sa_family == AF_INET) {
395 priority = origpriority;
396 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
397 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */
398 logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
402 if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
403 if(errno == EMSGSIZE) {
404 if(n->maxmtu >= origlen)
405 n->maxmtu = origlen - 1;
406 if(n->mtu >= origlen)
407 n->mtu = origlen - 1;
409 logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
413 origpkt->len = origlen;
417 send a packet to the given vpn ip.
419 void send_packet(const node_t *n, vpn_packet_t *packet)
427 memcpy(packet->data, mymac.x, ETH_ALEN);
428 write_packet(packet);
432 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
433 packet->len, n->name, n->hostname);
435 if(!n->status.reachable) {
436 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
437 n->name, n->hostname);
441 via = (n->via == myself) ? n->nexthop : n->via;
444 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
445 n->name, via->name, n->via->hostname);
447 if((myself->options | via->options) & OPTION_TCPONLY) {
448 if(!send_tcppacket(via->connection, packet))
449 terminate_connection(via->connection, true);
451 send_udppacket(via, packet);
454 /* Broadcast a packet using the minimum spanning tree */
456 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
463 ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
464 packet->len, from->name, from->hostname);
467 send_packet(myself, packet);
469 for(node = connection_tree->head; node; node = node->next) {
472 if(c->status.active && c->status.mst && c != from->nexthop->connection)
473 send_packet(c->node, packet);
477 void flush_queue(node_t *n)
479 list_node_t *node, *next;
483 ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
485 for(node = n->queue->head; node; node = next) {
487 send_udppacket(n, node->data);
488 list_delete_node(n->queue, node);
492 void handle_incoming_vpn_data(int sock)
497 socklen_t fromlen = sizeof(from);
502 pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
505 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
509 sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
511 n = lookup_node_udp(&from);
514 hostname = sockaddr2hostname(&from);
515 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
521 receive_udppacket(n, &pkt);