/* net_packet.c -- Handles in- and outgoing VPN packets Copyright (C) 1998-2003 Ivo Timmermans , 2000-2003 Guus Sliepen This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. $Id: net_packet.c,v 1.1.2.49 2003/12/27 16:32:52 guus Exp $ */ #include "system.h" #include #include #include #include #include #include #include #include "avl_tree.h" #include "conf.h" #include "connection.h" #include "device.h" #include "ethernet.h" #include "event.h" #include "graph.h" #include "list.h" #include "logger.h" #include "net.h" #include "netutl.h" #include "protocol.h" #include "process.h" #include "route.h" #include "utils.h" #include "xalloc.h" #ifdef WSAEMSGSIZE #define EMSGSIZE WSAEMSGSIZE #endif int keylifetime = 0; int keyexpires = 0; bool strictsource = true; EVP_CIPHER_CTX packet_ctx; static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS]; static void send_udppacket(node_t *, vpn_packet_t *); #define MAX_SEQNO 1073741824 void send_mtu_probe(node_t *n) { vpn_packet_t packet; int len, i; cp(); n->mtuprobes++; n->mtuevent = NULL; if(n->mtuprobes >= 10 && !n->minmtu) { ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname); return; } for(i = 0; i < 3; i++) { if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) { n->mtu = n->minmtu; ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes); return; } len = n->minmtu + 1 + random() % (n->maxmtu - n->minmtu); if(len < 64) len = 64; memset(packet.data, 0, 14); RAND_pseudo_bytes(packet.data + 14, len - 14); packet.len = len; ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname); send_udppacket(n, &packet); } n->mtuevent = xmalloc(sizeof(*n->mtuevent)); n->mtuevent->handler = (event_handler_t)send_mtu_probe; n->mtuevent->data = n; n->mtuevent->time = now + 1; event_add(n->mtuevent); } void mtu_probe_h(node_t *n, vpn_packet_t *packet) { ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname); if(!packet->data[0]) { packet->data[0] = 1; send_packet(n, packet); } else { if(n->minmtu < packet->len) n->minmtu = packet->len; } } static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) { if(level == 10) { lzo_uint lzolen = MAXSIZE; lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem); return lzolen; } else if(level < 10) { unsigned long destlen = MAXSIZE; if(compress2(dest, &destlen, source, len, level) == Z_OK) return destlen; else return -1; } else { lzo_uint lzolen = MAXSIZE; lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem); return lzolen; } return -1; } static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) { if(level > 9) { lzo_uint lzolen = MAXSIZE; if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK) return lzolen; else return -1; } else { unsigned long destlen = MAXSIZE; if(uncompress(dest, &destlen, source, len) == Z_OK) return destlen; else return -1; } return -1; } /* VPN packet I/O */ static void receive_packet(node_t *n, vpn_packet_t *packet) { cp(); ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"), packet->len, n->name, n->hostname); route(n, packet); } static bool authenticate_udppacket(node_t *n, vpn_packet_t *inpkt) { char hmac[EVP_MAX_MD_SIZE]; if(inpkt->len < sizeof(inpkt->seqno) + (myself->digest ? myself->maclength : 0)) return false; /* Check the message authentication code */ if(myself->digest && myself->maclength) { HMAC(myself->digest, myself->key, myself->keylength, (char *) &inpkt->seqno, inpkt->len - myself->maclength, hmac, NULL); if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len - myself->maclength, myself->maclength)) return false; } return true; } static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) { vpn_packet_t pkt1, pkt2; vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 }; int nextpkt = 0; vpn_packet_t *outpkt = pkt[0]; int outlen, outpad; int i; cp(); if(!authenticate_udppacket(n, inpkt)) { ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"), n->name, n->hostname); return; } inpkt->len -= myself->digest ? myself->maclength : 0; /* Decrypt the packet */ if(myself->cipher) { outpkt = pkt[nextpkt++]; if(!EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL) || !EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen, (char *) &inpkt->seqno, inpkt->len) || !EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) { ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"), n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL)); return; } outpkt->len = outlen + outpad; inpkt = outpkt; } /* Check the sequence number */ inpkt->len -= sizeof(inpkt->seqno); inpkt->seqno = ntohl(inpkt->seqno); if(inpkt->seqno != n->received_seqno + 1) { if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) { logger(LOG_WARNING, _("Lost %d packets from %s (%s)"), inpkt->seqno - n->received_seqno - 1, n->name, n->hostname); memset(n->late, 0, sizeof(n->late)); } else if (inpkt->seqno <= n->received_seqno) { if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) { logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"), n->name, n->hostname, inpkt->seqno, n->received_seqno); } else for(i = n->received_seqno + 1; i < inpkt->seqno; i++) n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8; } } n->received_seqno = inpkt->seqno; n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8); if(n->received_seqno > MAX_SEQNO) keyexpires = 0; /* Decompress the packet */ if(myself->compression) { outpkt = pkt[nextpkt++]; if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) { ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"), n->name, n->hostname); return; } inpkt = outpkt; } if(n->connection) n->connection->last_ping_time = now; if(!inpkt->data[12] && !inpkt->data[13]) mtu_probe_h(n, inpkt); else receive_packet(n, inpkt); } void receive_tcppacket(connection_t *c, char *buffer, int len) { vpn_packet_t outpkt; cp(); outpkt.len = len; memcpy(outpkt.data, buffer, len); receive_packet(c->node, &outpkt); } static void send_udppacket(node_t *n, vpn_packet_t *inpkt) { vpn_packet_t pkt1, pkt2; vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 }; int nextpkt = 0; vpn_packet_t *outpkt; int origlen; int outlen, outpad; vpn_packet_t *copy; static int priority = 0; int origpriority; int sock; cp(); /* Make sure we have a valid key */ if(!n->status.validkey) { ifdebug(TRAFFIC) logger(LOG_INFO, _("No valid key known yet for %s (%s), queueing packet"), n->name, n->hostname); /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */ *(copy = xmalloc(sizeof(*copy))) = *inpkt; list_insert_tail(n->queue, copy); if(n->queue->count > MAXQUEUELENGTH) list_delete_head(n->queue); if(!n->status.waitingforkey) send_req_key(n->nexthop->connection, myself, n); n->status.waitingforkey = true; return; } origlen = inpkt->len; origpriority = inpkt->priority; /* Compress the packet */ if(n->compression) { outpkt = pkt[nextpkt++]; if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) { ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"), n->name, n->hostname); return; } inpkt = outpkt; } /* Add sequence number */ inpkt->seqno = htonl(++(n->sent_seqno)); inpkt->len += sizeof(inpkt->seqno); /* Encrypt the packet */ if(n->cipher) { outpkt = pkt[nextpkt++]; if(!EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL) || !EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen, (char *) &inpkt->seqno, inpkt->len) || !EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) { ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"), n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL)); goto end; } outpkt->len = outlen + outpad; inpkt = outpkt; } /* Add the message authentication code */ if(n->digest && n->maclength) { HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno, inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen); inpkt->len += n->maclength; } /* Determine which socket we have to use */ for(sock = 0; sock < listen_sockets; sock++) if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family) break; if(sock >= listen_sockets) sock = 0; /* If none is available, just use the first and hope for the best. */ /* Send the packet */ #if defined(SOL_IP) && defined(IP_TOS) if(priorityinheritance && origpriority != priority && listen_socket[sock].sa.sa.sa_family == AF_INET) { priority = origpriority; ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority); if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */ logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno)); } #endif if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) { if(errno == EMSGSIZE) { if(n->maxmtu >= origlen) n->maxmtu = origlen - 1; if(n->mtu >= origlen) n->mtu = origlen - 1; } else logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno)); } end: inpkt->len = origlen; } /* send a packet to the given vpn ip. */ void send_packet(const node_t *n, vpn_packet_t *packet) { node_t *via; cp(); if(n == myself) { if(overwrite_mac) memcpy(packet->data, mymac.x, ETH_ALEN); write_packet(packet); return; } ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"), packet->len, n->name, n->hostname); if(!n->status.reachable) { ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"), n->name, n->hostname); return; } via = (n->via == myself) ? n->nexthop : n->via; if(via != n) ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"), n->name, via->name, n->via->hostname); if((myself->options | via->options) & OPTION_TCPONLY) { if(!send_tcppacket(via->connection, packet)) terminate_connection(via->connection, true); } else send_udppacket(via, packet); } /* Broadcast a packet using the minimum spanning tree */ void broadcast_packet(const node_t *from, vpn_packet_t *packet) { avl_node_t *node; connection_t *c; cp(); ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"), packet->len, from->name, from->hostname); for(node = connection_tree->head; node; node = node->next) { c = node->data; if(c->status.active && c->status.mst && c != from->nexthop->connection) send_packet(c->node, packet); } } void flush_queue(node_t *n) { list_node_t *node, *next; cp(); ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname); for(node = n->queue->head; node; node = next) { next = node->next; send_udppacket(n, node->data); list_delete_node(n->queue, node); } } void handle_incoming_vpn_data(int sock) { vpn_packet_t pkt; char *hostname; sockaddr_t from; socklen_t fromlen = sizeof(from); node_t *n; static time_t lasttime = 0; cp(); pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen); if(pkt.len < 0) { logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno)); return; } sockaddrunmap(&from); /* Some braindead IPv6 implementations do stupid things. */ n = lookup_node_udp(&from); if(!n && !strictsource && myself->digest && myself->maclength && lasttime != now) { avl_node_t *node; lasttime = now; for(node = node_tree->head; node; node = node->next) { n = node->data; if(authenticate_udppacket(n, &pkt)) { update_node_address(n, &from); logger(LOG_DEBUG, _("Updated address of node %s to %s"), n->name, n->hostname); break; } } } if(!n) { hostname = sockaddr2hostname(&from); logger(LOG_WARNING, _("Received UDP packet from unknown source %s"), hostname); free(hostname); return; } receive_udppacket(n, &pkt); }