2 net_packet.c -- Handles in- and outgoing VPN packets
3 Copyright (C) 1998-2004 Ivo Timmermans <ivo@tinc-vpn.org>,
4 2000-2004 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>
36 #include "connection.h"
52 #define EMSGSIZE WSAEMSGSIZE
57 EVP_CIPHER_CTX packet_ctx;
58 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
60 static void send_udppacket(node_t *, vpn_packet_t *);
62 #define MAX_SEQNO 1073741824
64 void send_mtu_probe(node_t *n)
74 if(n->mtuprobes >= 10 && !n->minmtu) {
75 ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname);
79 for(i = 0; i < 3; i++) {
80 if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) {
82 ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
86 len = n->minmtu + 1 + random() % (n->maxmtu - n->minmtu);
90 memset(packet.data, 0, 14);
91 RAND_pseudo_bytes(packet.data + 14, len - 14);
94 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
96 send_udppacket(n, &packet);
99 n->mtuevent = xmalloc(sizeof(*n->mtuevent));
100 n->mtuevent->handler = (event_handler_t)send_mtu_probe;
101 n->mtuevent->data = n;
102 n->mtuevent->time = now + 1;
103 event_add(n->mtuevent);
106 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
107 ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
109 if(!packet->data[0]) {
111 send_packet(n, packet);
113 if(n->minmtu < packet->len)
114 n->minmtu = packet->len;
118 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
121 lzo_uint lzolen = MAXSIZE;
122 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
124 } else if(level < 10) {
125 unsigned long destlen = MAXSIZE;
126 if(compress2(dest, &destlen, source, len, level) == Z_OK)
131 lzo_uint lzolen = MAXSIZE;
132 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
139 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
142 lzo_uint lzolen = MAXSIZE;
143 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
148 unsigned long destlen = MAXSIZE;
149 if(uncompress(dest, &destlen, source, len) == Z_OK)
160 static void receive_packet(node_t *n, vpn_packet_t *packet)
164 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
165 packet->len, n->name, n->hostname);
170 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
172 vpn_packet_t pkt1, pkt2;
173 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
175 vpn_packet_t *outpkt = pkt[0];
177 char hmac[EVP_MAX_MD_SIZE];
182 /* Check packet length */
184 if(inpkt->len < sizeof(inpkt->seqno) + myself->maclength) {
185 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
186 n->name, n->hostname);
190 /* Check the message authentication code */
192 if(myself->digest && myself->maclength) {
193 inpkt->len -= myself->maclength;
194 HMAC(myself->digest, myself->key, myself->keylength,
195 (char *) &inpkt->seqno, inpkt->len, hmac, NULL);
197 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
198 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
199 n->name, n->hostname);
204 /* Decrypt the packet */
207 outpkt = pkt[nextpkt++];
209 if(!EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL)
210 || !EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
211 (char *) &inpkt->seqno, inpkt->len)
212 || !EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
213 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
214 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
218 outpkt->len = outlen + outpad;
222 /* Check the sequence number */
224 inpkt->len -= sizeof(inpkt->seqno);
225 inpkt->seqno = ntohl(inpkt->seqno);
227 if(inpkt->seqno != n->received_seqno + 1) {
228 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
229 logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
230 inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
232 memset(n->late, 0, sizeof(n->late));
233 } else if (inpkt->seqno <= n->received_seqno) {
234 if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
235 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
236 n->name, n->hostname, inpkt->seqno, n->received_seqno);
240 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
241 n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
245 n->received_seqno = inpkt->seqno;
246 n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
248 if(n->received_seqno > MAX_SEQNO)
251 /* Decompress the packet */
253 if(myself->compression) {
254 outpkt = pkt[nextpkt++];
256 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
257 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
258 n->name, n->hostname);
266 n->connection->last_ping_time = now;
268 if(!inpkt->data[12] && !inpkt->data[13])
269 mtu_probe_h(n, inpkt);
271 receive_packet(n, inpkt);
274 void receive_tcppacket(connection_t *c, char *buffer, int len)
281 memcpy(outpkt.data, buffer, len);
283 receive_packet(c->node, &outpkt);
286 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
288 vpn_packet_t pkt1, pkt2;
289 vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
291 vpn_packet_t *outpkt;
295 static int priority = 0;
301 /* Make sure we have a valid key */
303 if(!n->status.validkey) {
304 ifdebug(TRAFFIC) logger(LOG_INFO,
305 _("No valid key known yet for %s (%s), queueing packet"),
306 n->name, n->hostname);
308 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
310 *(copy = xmalloc(sizeof(*copy))) = *inpkt;
312 list_insert_tail(n->queue, copy);
314 if(n->queue->count > MAXQUEUELENGTH)
315 list_delete_head(n->queue);
317 if(!n->status.waitingforkey)
318 send_req_key(n->nexthop->connection, myself, n);
320 n->status.waitingforkey = true;
325 origlen = inpkt->len;
326 origpriority = inpkt->priority;
328 /* Compress the packet */
331 outpkt = pkt[nextpkt++];
333 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
334 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
335 n->name, n->hostname);
342 /* Add sequence number */
344 inpkt->seqno = htonl(++(n->sent_seqno));
345 inpkt->len += sizeof(inpkt->seqno);
347 /* Encrypt the packet */
350 outpkt = pkt[nextpkt++];
352 if(!EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL)
353 || !EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
354 (char *) &inpkt->seqno, inpkt->len)
355 || !EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
356 ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
357 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
361 outpkt->len = outlen + outpad;
365 /* Add the message authentication code */
367 if(n->digest && n->maclength) {
368 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
369 inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
370 inpkt->len += n->maclength;
373 /* Determine which socket we have to use */
375 for(sock = 0; sock < listen_sockets; sock++)
376 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
379 if(sock >= listen_sockets)
380 sock = 0; /* If none is available, just use the first and hope for the best. */
382 /* Send the packet */
384 #if defined(SOL_IP) && defined(IP_TOS)
385 if(priorityinheritance && origpriority != priority
386 && listen_socket[sock].sa.sa.sa_family == AF_INET) {
387 priority = origpriority;
388 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
389 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */
390 logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
394 if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
395 if(errno == EMSGSIZE) {
396 if(n->maxmtu >= origlen)
397 n->maxmtu = origlen - 1;
398 if(n->mtu >= origlen)
399 n->mtu = origlen - 1;
401 logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
405 inpkt->len = origlen;
409 send a packet to the given vpn ip.
411 void send_packet(const node_t *n, vpn_packet_t *packet)
419 memcpy(packet->data, mymac.x, ETH_ALEN);
420 write_packet(packet);
424 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
425 packet->len, n->name, n->hostname);
427 if(!n->status.reachable) {
428 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
429 n->name, n->hostname);
433 via = (n->via == myself) ? n->nexthop : n->via;
436 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
437 n->name, via->name, n->via->hostname);
439 if((myself->options | via->options) & OPTION_TCPONLY) {
440 if(!send_tcppacket(via->connection, packet))
441 terminate_connection(via->connection, true);
443 send_udppacket(via, packet);
446 /* Broadcast a packet using the minimum spanning tree */
448 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
455 ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
456 packet->len, from->name, from->hostname);
458 for(node = connection_tree->head; node; node = node->next) {
461 if(c->status.active && c->status.mst && c != from->nexthop->connection)
462 send_packet(c->node, packet);
466 void flush_queue(node_t *n)
468 list_node_t *node, *next;
472 ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
474 for(node = n->queue->head; node; node = next) {
476 send_udppacket(n, node->data);
477 list_delete_node(n->queue, node);
481 void handle_incoming_vpn_data(int sock)
486 socklen_t fromlen = sizeof(from);
491 pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
494 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
498 sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */
500 n = lookup_node_udp(&from);
503 hostname = sockaddr2hostname(&from);
504 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
510 receive_udppacket(n, &pkt);