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 1.1.2.45 2003/12/20 19:47:52 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 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 for(i = 0; i < 3; i++) {
69 if(n->mtuprobes >= 100 || n->probedmtu >= n->mtu) {
70 n->mtu = n->probedmtu;
71 ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
75 len = n->probedmtu + 1 + random() % (n->mtu - n->probedmtu);
79 memset(packet.data, 0, 14);
80 RAND_pseudo_bytes(packet.data + 14, len - 14);
83 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
85 send_udppacket(n, &packet);
88 n->mtuevent = xmalloc(sizeof(*n->mtuevent));
89 n->mtuevent->handler = (event_handler_t)send_mtu_probe;
90 n->mtuevent->data = n;
91 n->mtuevent->time = now + 1;
92 event_add(n->mtuevent);
95 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
96 ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
98 if(!packet->data[0]) {
100 send_packet(n, packet);
102 if(n->probedmtu < packet->len)
103 n->probedmtu = packet->len;
107 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
110 lzo_uint lzolen = MAXSIZE;
111 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
113 } else if(level < 10) {
114 unsigned long destlen = MAXSIZE;
115 if(compress2(dest, &destlen, source, len, level) == Z_OK)
120 lzo_uint lzolen = MAXSIZE;
121 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
128 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
131 lzo_uint lzolen = MAXSIZE;
132 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
137 unsigned long destlen = MAXSIZE;
138 if(uncompress(dest, &destlen, source, len) == Z_OK)
149 static void receive_packet(node_t *n, vpn_packet_t *packet)
153 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
154 packet->len, n->name, n->hostname);
159 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
161 vpn_packet_t pkt1, pkt2;
162 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
164 vpn_packet_t *outpkt = pkt[0];
166 char hmac[EVP_MAX_MD_SIZE];
171 /* Check packet length */
173 if(inpkt->len < sizeof(inpkt->seqno) + myself->maclength) {
174 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
175 n->name, n->hostname);
179 /* Check the message authentication code */
181 if(myself->digest && myself->maclength) {
182 inpkt->len -= myself->maclength;
183 HMAC(myself->digest, myself->key, myself->keylength,
184 (char *) &inpkt->seqno, inpkt->len, hmac, NULL);
186 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
187 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
188 n->name, n->hostname);
193 /* Decrypt the packet */
196 outpkt = pkt[nextpkt++];
198 if(!EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL)
199 || !EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
200 (char *) &inpkt->seqno, inpkt->len)
201 || !EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
202 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
203 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
207 outpkt->len = outlen + outpad;
211 /* Check the sequence number */
213 inpkt->len -= sizeof(inpkt->seqno);
214 inpkt->seqno = ntohl(inpkt->seqno);
216 if(inpkt->seqno != n->received_seqno + 1) {
217 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
218 logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
219 inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
221 memset(n->late, 0, sizeof(n->late));
222 } else if (inpkt->seqno <= n->received_seqno) {
223 if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
224 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
225 n->name, n->hostname, inpkt->seqno, n->received_seqno);
227 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
228 n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
232 n->received_seqno = inpkt->seqno;
233 n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
235 if(n->received_seqno > MAX_SEQNO)
238 /* Decompress the packet */
240 if(myself->compression) {
241 outpkt = pkt[nextpkt++];
243 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
244 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
245 n->name, n->hostname);
253 n->connection->last_ping_time = now;
255 if(!inpkt->data[12] && !inpkt->data[13])
256 mtu_probe_h(n, inpkt);
258 receive_packet(n, inpkt);
261 void receive_tcppacket(connection_t *c, char *buffer, int len)
268 memcpy(outpkt.data, buffer, len);
270 receive_packet(c->node, &outpkt);
273 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
275 vpn_packet_t pkt1, pkt2;
276 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
278 vpn_packet_t *outpkt;
282 static int priority = 0;
288 /* Make sure we have a valid key */
290 if(!n->status.validkey) {
291 ifdebug(TRAFFIC) logger(LOG_INFO,
292 _("No valid key known yet for %s (%s), queueing packet"),
293 n->name, n->hostname);
295 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
297 *(copy = xmalloc(sizeof(*copy))) = *inpkt;
299 list_insert_tail(n->queue, copy);
301 if(n->queue->count > MAXQUEUELENGTH)
302 list_delete_head(n->queue);
304 if(!n->status.waitingforkey)
305 send_req_key(n->nexthop->connection, myself, n);
307 n->status.waitingforkey = true;
312 origlen = inpkt->len;
313 origpriority = inpkt->priority;
315 /* Compress the packet */
318 outpkt = pkt[nextpkt++];
320 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
321 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
322 n->name, n->hostname);
329 /* Add sequence number */
331 inpkt->seqno = htonl(++(n->sent_seqno));
332 inpkt->len += sizeof(inpkt->seqno);
334 /* Encrypt the packet */
337 outpkt = pkt[nextpkt++];
339 if(!EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL)
340 || !EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
341 (char *) &inpkt->seqno, inpkt->len)
342 || !EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
343 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
344 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
348 outpkt->len = outlen + outpad;
352 /* Add the message authentication code */
354 if(n->digest && n->maclength) {
355 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
356 inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
357 inpkt->len += n->maclength;
360 /* Determine which socket we have to use */
362 for(sock = 0; sock < listen_sockets; sock++)
363 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
366 if(sock >= listen_sockets)
367 sock = 0; /* If none is available, just use the first and hope for the best. */
369 /* Send the packet */
371 #if defined(SOL_IP) && defined(IP_TOS)
372 if(priorityinheritance && origpriority != priority
373 && listen_socket[sock].sa.sa.sa_family == AF_INET) {
374 priority = origpriority;
375 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
376 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */
377 logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
381 if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
382 logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
383 if(errno == EMSGSIZE) {
384 if(n->mtu >= origlen)
385 n->mtu = origlen - 1;
390 inpkt->len = origlen;
394 send a packet to the given vpn ip.
396 void send_packet(const node_t *n, vpn_packet_t *packet)
403 write_packet(packet);
407 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
408 packet->len, n->name, n->hostname);
410 if(!n->status.reachable) {
411 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
412 n->name, n->hostname);
416 via = (n->via == myself) ? n->nexthop : n->via;
419 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
420 n->name, via->name, n->via->hostname);
422 if((myself->options | via->options) & OPTION_TCPONLY) {
423 if(!send_tcppacket(via->connection, packet))
424 terminate_connection(via->connection, true);
426 send_udppacket(via, packet);
429 /* Broadcast a packet using the minimum spanning tree */
431 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
438 ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
439 packet->len, from->name, from->hostname);
441 for(node = connection_tree->head; node; node = node->next) {
444 if(c->status.active && c->status.mst && c != from->nexthop->connection)
445 send_packet(c->node, packet);
449 void flush_queue(node_t *n)
451 list_node_t *node, *next;
455 ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
457 for(node = n->queue->head; node; node = next) {
459 send_udppacket(n, node->data);
460 list_delete_node(n->queue, node);
464 void handle_incoming_vpn_data(int sock)
469 socklen_t fromlen = sizeof(from);
474 pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
477 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
481 sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
483 n = lookup_node_udp(&from);
486 hostname = sockaddr2hostname(&from);
487 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
493 receive_udppacket(n, &pkt);