/* net_packet.c -- Handles in- and outgoing VPN packets Copyright (C) 1998-2002 Ivo Timmermans , 2000-2002 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 1.1.2.8 2002/03/01 15:14:29 guus Exp $ */ #include "config.h" #include #include #include #include #ifdef HAVE_LINUX #include #include #endif #include #include #include #include #include #include #include #include #include /* SunOS really wants sys/socket.h BEFORE net/if.h, and FreeBSD wants these lines below the rest. */ #include #include #include #include #include #include #include #ifndef HAVE_RAND_PSEUDO_BYTES #define RAND_pseudo_bytes RAND_bytes #endif #include #include #include #include #include #include "conf.h" #include "connection.h" #include "meta.h" #include "net.h" #include "netutl.h" #include "process.h" #include "protocol.h" #include "subnet.h" #include "graph.h" #include "process.h" #include "route.h" #include "device.h" #include "event.h" #include "system.h" int keylifetime = 0; int keyexpires = 0; #define MAX_SEQNO 1073741824 /* VPN packet I/O */ 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; long int complen = MTU + 12; EVP_CIPHER_CTX ctx; char hmac[EVP_MAX_MD_SIZE]; cp /* Check the message authentication code */ if(myself->digest && myself->maclength) { inpkt->len -= myself->maclength; HMAC(myself->digest, myself->key, myself->keylength, (char *)&inpkt->seqno, inpkt->len, hmac, NULL); if(memcmp(hmac, (char *)&inpkt->seqno + inpkt->len, myself->maclength)) { syslog(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"), n->name, n->hostname); return; } } /* Decrypt the packet */ if(myself->cipher) { outpkt = pkt[nextpkt++]; EVP_DecryptInit(&ctx, myself->cipher, myself->key, myself->key + myself->cipher->key_len); EVP_DecryptUpdate(&ctx, (char *)&outpkt->seqno, &outlen, (char *)&inpkt->seqno, inpkt->len); EVP_DecryptFinal(&ctx, (char *)&outpkt->seqno + outlen, &outpad); 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) { syslog(LOG_DEBUG, _("Got late or replayed packet from %s (%s), seqno %d"), n->name, n->hostname, inpkt->seqno); return; } n->received_seqno = inpkt->seqno; if(n->received_seqno > MAX_SEQNO) keyexpires = 0; /* Decompress the packet */ if(myself->compression) { outpkt = pkt[nextpkt++]; if(uncompress(outpkt->data, &complen, inpkt->data, inpkt->len) != Z_OK) { syslog(LOG_ERR, _("Error while uncompressing packet from %s (%s)"), n->name, n->hostname); return; } outpkt->len = complen; inpkt = outpkt; } receive_packet(n, inpkt); cp } 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); cp } void receive_packet(node_t *n, vpn_packet_t *packet) { cp if(debug_lvl >= DEBUG_TRAFFIC) syslog(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"), packet->len, n->name, n->hostname); route_incoming(n, packet); cp } 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; long int complen = MTU + 12; EVP_CIPHER_CTX ctx; vpn_packet_t *copy; static int priority = 0; int origpriority; cp if(!n->status.validkey) { if(debug_lvl >= DEBUG_TRAFFIC) syslog(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(vpn_packet_t)); memcpy(copy, inpkt, sizeof(vpn_packet_t)); list_insert_tail(n->queue, copy); if(!n->status.waitingforkey) send_req_key(n->nexthop->connection, myself, n); return; } origlen = inpkt->len; origpriority = inpkt->priority; /* Compress the packet */ if(n->compression) { outpkt = pkt[nextpkt++]; if(compress2(outpkt->data, &complen, inpkt->data, inpkt->len, n->compression) != Z_OK) { syslog(LOG_ERR, _("Error while compressing packet to %s (%s)"), n->name, n->hostname); return; } outpkt->len = complen; 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++]; EVP_EncryptInit(&ctx, n->cipher, n->key, n->key + n->cipher->key_len); EVP_EncryptUpdate(&ctx, (char *)&outpkt->seqno, &outlen, (char *)&inpkt->seqno, inpkt->len); EVP_EncryptFinal(&ctx, (char *)&outpkt->seqno + outlen, &outpad); 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; } /* Send the packet */ #if defined(SOL_IP) && defined(IP_TOS) if(priorityinheritance && origpriority != priority) { priority = origpriority; if(debug_lvl >= DEBUG_TRAFFIC) syslog(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority); if(setsockopt(udp_socket[0], SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */ syslog(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno)); } #endif if((sendto(udp_socket[0], (char *)&inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) { syslog(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno)); return; } inpkt->len = origlen; cp } /* send a packet to the given vpn ip. */ void send_packet(node_t *n, vpn_packet_t *packet) { node_t *via; cp if(debug_lvl >= DEBUG_TRAFFIC) syslog(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"), packet->len, n->name, n->hostname); if(n == myself) { if(debug_lvl >= DEBUG_TRAFFIC) { syslog(LOG_NOTICE, _("Packet is looping back to us!")); } return; } if(!n->status.reachable) { if(debug_lvl >= DEBUG_TRAFFIC) syslog(LOG_INFO, _("Node %s (%s) is not reachable"), n->name, n->hostname); return; } via = (n->via == myself)?n->nexthop:n->via; if(via != n && debug_lvl >= DEBUG_TRAFFIC) syslog(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, 1); } else send_udppacket(via, packet); } /* Broadcast a packet using the minimum spanning tree */ void broadcast_packet(node_t *from, vpn_packet_t *packet) { avl_node_t *node; connection_t *c; cp if(debug_lvl >= DEBUG_TRAFFIC) syslog(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 = (connection_t *)node->data; if(c->status.active && c->status.mst && c != from->nexthop->connection) send_packet(c->node, packet); } cp } void flush_queue(node_t *n) { list_node_t *node, *next; cp if(debug_lvl >= DEBUG_TRAFFIC) syslog(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, (vpn_packet_t *)node->data); list_delete_node(n->queue, node); } cp } void handle_incoming_vpn_data(int sock) { vpn_packet_t pkt; int x, l = sizeof(x); char *hostname; sockaddr_t from; socklen_t fromlen = sizeof(from); node_t *n; cp if(getsockopt(sock, SOL_SOCKET, SO_ERROR, &x, &l) < 0) { syslog(LOG_ERR, _("This is a bug: %s:%d: %d:%s"), __FILE__, __LINE__, sock, strerror(errno)); cp_trace(); exit(1); } if(x) { syslog(LOG_ERR, _("Incoming data socket error: %s"), strerror(x)); return; } if((pkt.len = recvfrom(sock, (char *)&pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen)) <= 0) { syslog(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno)); return; } n = lookup_node_udp(&from); if(!n) { hostname = sockaddr2hostname(&from); syslog(LOG_WARNING, _("Received UDP packet from unknown source %s"), hostname); free(hostname); return; } if(n->connection) n->connection->last_ping_time = now; receive_udppacket(n, &pkt); cp }