2 net_packet.c -- Handles in- and outgoing VPN packets
3 Copyright (C) 1998-2003 Ivo Timmermans <ivo@o2w.nl>,
4 2000-2003 Guus Sliepen <guus@sliepen.eu.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.
20 $Id: net_packet.c,v 1.1.2.46 2003/12/20 21:09:33 guus Exp $
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>
36 #include "connection.h"
52 EVP_CIPHER_CTX packet_ctx;
53 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
55 static void send_udppacket(node_t *, vpn_packet_t *);
57 #define MAX_SEQNO 1073741824
59 void send_mtu_probe(node_t *n)
68 if(n->mtuprobes >= 10 && !n->probedmtu) {
69 ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname);
73 for(i = 0; i < 3; i++) {
74 if(n->mtuprobes >= 30 || n->probedmtu >= n->mtu) {
75 n->mtu = n->probedmtu;
76 ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
80 len = n->probedmtu + 1 + random() % (n->mtu - n->probedmtu);
84 memset(packet.data, 0, 14);
85 RAND_pseudo_bytes(packet.data + 14, len - 14);
88 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
90 send_udppacket(n, &packet);
93 n->mtuevent = xmalloc(sizeof(*n->mtuevent));
94 n->mtuevent->handler = (event_handler_t)send_mtu_probe;
95 n->mtuevent->data = n;
96 n->mtuevent->time = now + 1;
97 event_add(n->mtuevent);
100 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
101 ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
103 if(!packet->data[0]) {
105 send_packet(n, packet);
107 if(n->probedmtu < packet->len)
108 n->probedmtu = packet->len;
112 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
115 lzo_uint lzolen = MAXSIZE;
116 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
118 } else if(level < 10) {
119 unsigned long destlen = MAXSIZE;
120 if(compress2(dest, &destlen, source, len, level) == Z_OK)
125 lzo_uint lzolen = MAXSIZE;
126 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
133 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
136 lzo_uint lzolen = MAXSIZE;
137 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
142 unsigned long destlen = MAXSIZE;
143 if(uncompress(dest, &destlen, source, len) == Z_OK)
154 static void receive_packet(node_t *n, vpn_packet_t *packet)
158 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
159 packet->len, n->name, n->hostname);
164 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
166 vpn_packet_t pkt1, pkt2;
167 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
169 vpn_packet_t *outpkt = pkt[0];
171 char hmac[EVP_MAX_MD_SIZE];
176 /* Check packet length */
178 if(inpkt->len < sizeof(inpkt->seqno) + myself->maclength) {
179 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
180 n->name, n->hostname);
184 /* Check the message authentication code */
186 if(myself->digest && myself->maclength) {
187 inpkt->len -= myself->maclength;
188 HMAC(myself->digest, myself->key, myself->keylength,
189 (char *) &inpkt->seqno, inpkt->len, hmac, NULL);
191 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
192 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
193 n->name, n->hostname);
198 /* Decrypt the packet */
201 outpkt = pkt[nextpkt++];
203 if(!EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL)
204 || !EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
205 (char *) &inpkt->seqno, inpkt->len)
206 || !EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
207 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
208 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
212 outpkt->len = outlen + outpad;
216 /* Check the sequence number */
218 inpkt->len -= sizeof(inpkt->seqno);
219 inpkt->seqno = ntohl(inpkt->seqno);
221 if(inpkt->seqno != n->received_seqno + 1) {
222 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
223 logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
224 inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
226 memset(n->late, 0, sizeof(n->late));
227 } else if (inpkt->seqno <= n->received_seqno) {
228 if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
229 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
230 n->name, n->hostname, inpkt->seqno, n->received_seqno);
232 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
233 n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
237 n->received_seqno = inpkt->seqno;
238 n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
240 if(n->received_seqno > MAX_SEQNO)
243 /* Decompress the packet */
245 if(myself->compression) {
246 outpkt = pkt[nextpkt++];
248 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
249 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
250 n->name, n->hostname);
258 n->connection->last_ping_time = now;
260 if(!inpkt->data[12] && !inpkt->data[13])
261 mtu_probe_h(n, inpkt);
263 receive_packet(n, inpkt);
266 void receive_tcppacket(connection_t *c, char *buffer, int len)
273 memcpy(outpkt.data, buffer, len);
275 receive_packet(c->node, &outpkt);
278 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
280 vpn_packet_t pkt1, pkt2;
281 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
283 vpn_packet_t *outpkt;
287 static int priority = 0;
293 /* Make sure we have a valid key */
295 if(!n->status.validkey) {
296 ifdebug(TRAFFIC) logger(LOG_INFO,
297 _("No valid key known yet for %s (%s), queueing packet"),
298 n->name, n->hostname);
300 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
302 *(copy = xmalloc(sizeof(*copy))) = *inpkt;
304 list_insert_tail(n->queue, copy);
306 if(n->queue->count > MAXQUEUELENGTH)
307 list_delete_head(n->queue);
309 if(!n->status.waitingforkey)
310 send_req_key(n->nexthop->connection, myself, n);
312 n->status.waitingforkey = true;
317 origlen = inpkt->len;
318 origpriority = inpkt->priority;
320 /* Compress the packet */
323 outpkt = pkt[nextpkt++];
325 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
326 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
327 n->name, n->hostname);
334 /* Add sequence number */
336 inpkt->seqno = htonl(++(n->sent_seqno));
337 inpkt->len += sizeof(inpkt->seqno);
339 /* Encrypt the packet */
342 outpkt = pkt[nextpkt++];
344 if(!EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL)
345 || !EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
346 (char *) &inpkt->seqno, inpkt->len)
347 || !EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
348 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
349 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
353 outpkt->len = outlen + outpad;
357 /* Add the message authentication code */
359 if(n->digest && n->maclength) {
360 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
361 inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
362 inpkt->len += n->maclength;
365 /* Determine which socket we have to use */
367 for(sock = 0; sock < listen_sockets; sock++)
368 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
371 if(sock >= listen_sockets)
372 sock = 0; /* If none is available, just use the first and hope for the best. */
374 /* Send the packet */
376 #if defined(SOL_IP) && defined(IP_TOS)
377 if(priorityinheritance && origpriority != priority
378 && listen_socket[sock].sa.sa.sa_family == AF_INET) {
379 priority = origpriority;
380 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
381 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */
382 logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
386 if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
387 logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
388 if(errno == EMSGSIZE) {
389 if(n->mtu >= origlen)
390 n->mtu = origlen - 1;
395 inpkt->len = origlen;
399 send a packet to the given vpn ip.
401 void send_packet(const node_t *n, vpn_packet_t *packet)
408 write_packet(packet);
412 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
413 packet->len, n->name, n->hostname);
415 if(!n->status.reachable) {
416 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
417 n->name, n->hostname);
421 via = (n->via == myself) ? n->nexthop : n->via;
424 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
425 n->name, via->name, n->via->hostname);
427 if((myself->options | via->options) & OPTION_TCPONLY) {
428 if(!send_tcppacket(via->connection, packet))
429 terminate_connection(via->connection, true);
431 send_udppacket(via, packet);
434 /* Broadcast a packet using the minimum spanning tree */
436 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
443 ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
444 packet->len, from->name, from->hostname);
446 for(node = connection_tree->head; node; node = node->next) {
449 if(c->status.active && c->status.mst && c != from->nexthop->connection)
450 send_packet(c->node, packet);
454 void flush_queue(node_t *n)
456 list_node_t *node, *next;
460 ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
462 for(node = n->queue->head; node; node = next) {
464 send_udppacket(n, node->data);
465 list_delete_node(n->queue, node);
469 void handle_incoming_vpn_data(int sock)
474 socklen_t fromlen = sizeof(from);
479 pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
482 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
486 sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
488 n = lookup_node_udp(&from);
491 hostname = sockaddr2hostname(&from);
492 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
498 receive_udppacket(n, &pkt);