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 1.1.2.49 2003/12/27 16:32:52 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 #define EMSGSIZE WSAEMSGSIZE
57 bool strictsource = true;
58 EVP_CIPHER_CTX packet_ctx;
59 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 void send_mtu_probe(node_t *n)
75 if(n->mtuprobes >= 10 && !n->minmtu) {
76 ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname);
80 for(i = 0; i < 3; i++) {
81 if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) {
83 ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
87 len = n->minmtu + 1 + random() % (n->maxmtu - n->minmtu);
91 memset(packet.data, 0, 14);
92 RAND_pseudo_bytes(packet.data + 14, len - 14);
95 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
97 send_udppacket(n, &packet);
100 n->mtuevent = xmalloc(sizeof(*n->mtuevent));
101 n->mtuevent->handler = (event_handler_t)send_mtu_probe;
102 n->mtuevent->data = n;
103 n->mtuevent->time = now + 1;
104 event_add(n->mtuevent);
107 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
108 ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
110 if(!packet->data[0]) {
112 send_packet(n, packet);
114 if(n->minmtu < packet->len)
115 n->minmtu = packet->len;
119 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
122 lzo_uint lzolen = MAXSIZE;
123 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
125 } else if(level < 10) {
126 unsigned long destlen = MAXSIZE;
127 if(compress2(dest, &destlen, source, len, level) == Z_OK)
132 lzo_uint lzolen = MAXSIZE;
133 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
140 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
143 lzo_uint lzolen = MAXSIZE;
144 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
149 unsigned long destlen = MAXSIZE;
150 if(uncompress(dest, &destlen, source, len) == Z_OK)
161 static void receive_packet(node_t *n, vpn_packet_t *packet)
165 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
166 packet->len, n->name, n->hostname);
171 static bool authenticate_udppacket(node_t *n, vpn_packet_t *inpkt) {
172 char hmac[EVP_MAX_MD_SIZE];
174 if(inpkt->len < sizeof(inpkt->seqno) + (myself->digest ? myself->maclength : 0))
177 /* Check the message authentication code */
179 if(myself->digest && myself->maclength) {
180 HMAC(myself->digest, myself->key, myself->keylength,
181 (char *) &inpkt->seqno, inpkt->len - myself->maclength, hmac, NULL);
183 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len - myself->maclength, myself->maclength))
190 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
192 vpn_packet_t pkt1, pkt2;
193 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
195 vpn_packet_t *outpkt = pkt[0];
201 if(!authenticate_udppacket(n, inpkt)) {
202 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
203 n->name, n->hostname);
207 inpkt->len -= myself->digest ? myself->maclength : 0;
209 /* Decrypt the packet */
212 outpkt = pkt[nextpkt++];
214 if(!EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL)
215 || !EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
216 (char *) &inpkt->seqno, inpkt->len)
217 || !EVP_DecryptFinal_ex(&packet_ctx, (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(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);
243 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
244 n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
248 n->received_seqno = inpkt->seqno;
249 n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
251 if(n->received_seqno > MAX_SEQNO)
254 /* Decompress the packet */
256 if(myself->compression) {
257 outpkt = pkt[nextpkt++];
259 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
260 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
261 n->name, n->hostname);
269 n->connection->last_ping_time = now;
271 if(!inpkt->data[12] && !inpkt->data[13])
272 mtu_probe_h(n, inpkt);
274 receive_packet(n, inpkt);
277 void receive_tcppacket(connection_t *c, char *buffer, int len)
284 memcpy(outpkt.data, buffer, len);
286 receive_packet(c->node, &outpkt);
289 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
291 vpn_packet_t pkt1, pkt2;
292 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
294 vpn_packet_t *outpkt;
298 static int priority = 0;
304 /* Make sure we have a valid key */
306 if(!n->status.validkey) {
307 ifdebug(TRAFFIC) logger(LOG_INFO,
308 _("No valid key known yet for %s (%s), queueing packet"),
309 n->name, n->hostname);
311 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
313 *(copy = xmalloc(sizeof(*copy))) = *inpkt;
315 list_insert_tail(n->queue, copy);
317 if(n->queue->count > MAXQUEUELENGTH)
318 list_delete_head(n->queue);
320 if(!n->status.waitingforkey)
321 send_req_key(n->nexthop->connection, myself, n);
323 n->status.waitingforkey = true;
328 origlen = inpkt->len;
329 origpriority = inpkt->priority;
331 /* Compress the packet */
334 outpkt = pkt[nextpkt++];
336 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
337 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
338 n->name, n->hostname);
345 /* Add sequence number */
347 inpkt->seqno = htonl(++(n->sent_seqno));
348 inpkt->len += sizeof(inpkt->seqno);
350 /* Encrypt the packet */
353 outpkt = pkt[nextpkt++];
355 if(!EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL)
356 || !EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
357 (char *) &inpkt->seqno, inpkt->len)
358 || !EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
359 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
360 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
364 outpkt->len = outlen + outpad;
368 /* Add the message authentication code */
370 if(n->digest && n->maclength) {
371 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
372 inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
373 inpkt->len += n->maclength;
376 /* Determine which socket we have to use */
378 for(sock = 0; sock < listen_sockets; sock++)
379 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
382 if(sock >= listen_sockets)
383 sock = 0; /* If none is available, just use the first and hope for the best. */
385 /* Send the packet */
387 #if defined(SOL_IP) && defined(IP_TOS)
388 if(priorityinheritance && origpriority != priority
389 && listen_socket[sock].sa.sa.sa_family == AF_INET) {
390 priority = origpriority;
391 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
392 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */
393 logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
397 if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
398 if(errno == EMSGSIZE) {
399 if(n->maxmtu >= origlen)
400 n->maxmtu = origlen - 1;
401 if(n->mtu >= origlen)
402 n->mtu = origlen - 1;
404 logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
408 inpkt->len = origlen;
412 send a packet to the given vpn ip.
414 void send_packet(const node_t *n, vpn_packet_t *packet)
422 memcpy(packet->data, mymac.x, ETH_ALEN);
423 write_packet(packet);
427 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
428 packet->len, n->name, n->hostname);
430 if(!n->status.reachable) {
431 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
432 n->name, n->hostname);
436 via = (n->via == myself) ? n->nexthop : n->via;
439 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
440 n->name, via->name, n->via->hostname);
442 if((myself->options | via->options) & OPTION_TCPONLY) {
443 if(!send_tcppacket(via->connection, packet))
444 terminate_connection(via->connection, true);
446 send_udppacket(via, packet);
449 /* Broadcast a packet using the minimum spanning tree */
451 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
458 ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
459 packet->len, from->name, from->hostname);
461 for(node = connection_tree->head; node; node = node->next) {
464 if(c->status.active && c->status.mst && c != from->nexthop->connection)
465 send_packet(c->node, packet);
469 void flush_queue(node_t *n)
471 list_node_t *node, *next;
475 ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
477 for(node = n->queue->head; node; node = next) {
479 send_udppacket(n, node->data);
480 list_delete_node(n->queue, node);
484 void handle_incoming_vpn_data(int sock)
489 socklen_t fromlen = sizeof(from);
491 static time_t lasttime = 0;
495 pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
498 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
502 sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
504 n = lookup_node_udp(&from);
506 if(!n && !strictsource && myself->digest && myself->maclength && lasttime != now) {
511 for(node = node_tree->head; node; node = node->next) {
514 if(authenticate_udppacket(n, &pkt)) {
515 update_node_address(n, &from);
516 logger(LOG_DEBUG, _("Updated address of node %s to %s"), n->name, n->hostname);
523 hostname = sockaddr2hostname(&from);
524 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"), hostname);
529 receive_udppacket(n, &pkt);