/* route.c -- routing Copyright (C) 2000-2003 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: route.c,v 1.1.2.68 2003/10/06 13:57:12 guus Exp $ */ #include "system.h" #ifdef HAVE_NET_ETHERNET_H #include #endif #ifdef HAVE_NET_IF_ARP_H #include #endif #ifdef HAVE_NETINET_IP_ICMP_H #include #endif #ifdef HAVE_NETINET_ICMP6_H #include #endif #ifdef HAVE_NETINET_IF_ETHER_H #include #endif #include "avl_tree.h" #include "connection.h" #include "device.h" #include "ethernet.h" #include "ipv4.h" #include "ipv6.h" #include "logger.h" #include "net.h" #include "protocol.h" #include "route.h" #include "subnet.h" #include "utils.h" rmode_t routing_mode = RMODE_ROUTER; bool priorityinheritance = false; int macexpire = 600; bool overwrite_mac = false; mac_t mymac = {{0xFE, 0xFD, 0, 0, 0, 0}}; /* Sizes of various headers */ static const size_t ether_size = sizeof(struct ether_header); static const size_t arp_size = sizeof(struct ether_arp); static const size_t ip_size = sizeof(struct ip); static const size_t icmp_size = sizeof(struct icmp) - sizeof(struct ip); static const size_t ip6_size = sizeof(struct ip6_hdr); static const size_t icmp6_size = sizeof(struct icmp6_hdr); static const size_t ns_size = sizeof(struct nd_neighbor_solicit); static const size_t opt_size = sizeof(struct nd_opt_hdr); /* RFC 1071 */ static uint16_t inet_checksum(void *data, int len, uint16_t prevsum) { uint16_t *p = data; uint32_t checksum = prevsum ^ 0xFFFF; while(len >= 2) { checksum += *p++; len -= 2; } if(len) checksum += *(unsigned char *)p; while(checksum >> 16) checksum = (checksum & 0xFFFF) + (checksum >> 16); return ~checksum; } static bool ratelimit(int frequency) { static time_t lasttime = 0; static int count = 0; if(lasttime == now) { if(++count > frequency) return true; } else { lasttime = now; count = 0; } return false; } static void learn_mac(mac_t *address) { subnet_t *subnet; avl_node_t *node; connection_t *c; cp(); subnet = lookup_subnet_mac(address); /* If we don't know this MAC address yet, store it */ if(!subnet || subnet->owner != myself) { ifdebug(TRAFFIC) logger(LOG_INFO, _("Learned new MAC address %hx:%hx:%hx:%hx:%hx:%hx"), address->x[0], address->x[1], address->x[2], address->x[3], address->x[4], address->x[5]); subnet = new_subnet(); subnet->type = SUBNET_MAC; memcpy(&subnet->net.mac.address, address, sizeof(mac_t)); subnet_add(myself, subnet); /* And tell all other tinc daemons it's our MAC */ for(node = connection_tree->head; node; node = node->next) { c = node->data; if(c->status.active) send_add_subnet(c, subnet); } } subnet->net.mac.lastseen = now; } void age_mac(void) { subnet_t *s; connection_t *c; avl_node_t *node, *next, *node2; cp(); for(node = myself->subnet_tree->head; node; node = next) { next = node->next; s = node->data; if(s->type == SUBNET_MAC && s->net.mac.lastseen && s->net.mac.lastseen + macexpire < now) { ifdebug(TRAFFIC) logger(LOG_INFO, _("MAC address %hx:%hx:%hx:%hx:%hx:%hx expired"), s->net.mac.address.x[0], s->net.mac.address.x[1], s->net.mac.address.x[2], s->net.mac.address.x[3], s->net.mac.address.x[4], s->net.mac.address.x[5]); for(node2 = connection_tree->head; node2; node2 = node2->next) { c = node2->data; if(c->status.active) send_del_subnet(c, s); } subnet_del(myself, s); } } } static node_t *route_mac(vpn_packet_t *packet) { subnet_t *subnet; cp(); /* Learn source address */ learn_mac((mac_t *)(&packet->data[6])); /* Lookup destination address */ subnet = lookup_subnet_mac((mac_t *)(&packet->data[0])); if(subnet) return subnet->owner; else return NULL; } /* RFC 792 */ static void route_ipv4_unreachable(vpn_packet_t *packet, uint8_t code) { struct ip ip; struct icmp icmp; struct in_addr ip_src; struct in_addr ip_dst; uint32_t oldlen; if(ratelimit(3)) return; cp(); /* Copy headers from packet into properly aligned structs on the stack */ memcpy(&ip, packet->data + ether_size, ip_size); memcpy(&icmp, packet->data + ether_size + ip_size, icmp_size); /* Remember original source and destination */ memcpy(&ip_src, &ip.ip_src, sizeof(ip_src)); memcpy(&ip_dst, &ip.ip_dst, sizeof(ip_dst)); oldlen = packet->len - ether_size; if(oldlen >= IP_MSS - ip_size - icmp_size) oldlen = IP_MSS - ip_size - icmp_size; /* Copy first part of original contents to ICMP message */ memmove(packet->data + ether_size + ip_size + icmp_size, packet->data + ether_size, oldlen); /* Fill in IPv4 header */ ip.ip_v = 4; ip.ip_hl = ip_size / 4; ip.ip_tos = 0; ip.ip_len = htons(ip_size + icmp_size + oldlen); ip.ip_id = 0; ip.ip_off = 0; ip.ip_ttl = 255; ip.ip_p = IPPROTO_ICMP; ip.ip_sum = 0; memcpy(&ip.ip_src, &ip_dst, sizeof(ip_src)); memcpy(&ip.ip_dst, &ip_src, sizeof(ip_dst)); ip.ip_sum = inet_checksum(&ip, ip_size, ~0); /* Fill in ICMP header */ icmp.icmp_type = ICMP_DEST_UNREACH; icmp.icmp_code = code; icmp.icmp_cksum = 0; icmp.icmp_cksum = inet_checksum(&icmp, icmp_size, ~0); icmp.icmp_cksum = inet_checksum(packet->data + ether_size + ip_size + icmp_size, oldlen, icmp.icmp_cksum); /* Copy structs on stack back to packet */ memcpy(packet->data + ether_size, &ip, ip_size); memcpy(packet->data + ether_size + ip_size, &icmp, icmp_size); packet->len = ether_size + ip_size + icmp_size + oldlen; write_packet(packet); } static node_t *route_ipv4(vpn_packet_t *packet) { subnet_t *subnet; cp(); if(priorityinheritance) packet->priority = packet->data[15]; subnet = lookup_subnet_ipv4((ipv4_t *) &packet->data[30]); if(!subnet) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: unknown IPv4 destination address %d.%d.%d.%d"), packet->data[30], packet->data[31], packet->data[32], packet->data[33]); route_ipv4_unreachable(packet, ICMP_NET_UNKNOWN); return NULL; } if(!subnet->owner->status.reachable) route_ipv4_unreachable(packet, ICMP_NET_UNREACH); return subnet->owner; } /* RFC 2463 */ static void route_ipv6_unreachable(vpn_packet_t *packet, uint8_t code) { struct ip6_hdr ip6; struct icmp6_hdr icmp6; uint16_t checksum; struct { struct in6_addr ip6_src; /* source address */ struct in6_addr ip6_dst; /* destination address */ uint32_t length; uint32_t next; } pseudo; if(ratelimit(3)) return; cp(); /* Copy headers from packet to structs on the stack */ memcpy(&ip6, packet->data + ether_size, ip6_size); memcpy(&icmp6, packet->data + ether_size + ip6_size, icmp6_size); /* Remember original source and destination */ memcpy(&pseudo.ip6_src, &ip6.ip6_dst, sizeof(ip6.ip6_src)); memcpy(&pseudo.ip6_dst, &ip6.ip6_src, sizeof(ip6.ip6_dst)); pseudo.length = ntohs(ip6.ip6_plen) + ip6_size; if(pseudo.length >= IP_MSS - ip6_size - icmp6_size) pseudo.length = IP_MSS - ip6_size - icmp6_size; /* Copy first part of original contents to ICMP message */ memmove(packet->data + ether_size + ip6_size + icmp6_size, packet->data + ether_size, pseudo.length); /* Fill in IPv6 header */ ip6.ip6_flow = htonl(0x60000000UL); ip6.ip6_plen = htons(icmp6_size + pseudo.length); ip6.ip6_nxt = IPPROTO_ICMPV6; ip6.ip6_hlim = 255; memcpy(&ip6.ip6_src, &pseudo.ip6_src, sizeof(ip6.ip6_src)); memcpy(&ip6.ip6_dst, &pseudo.ip6_dst, sizeof(ip6.ip6_dst)); /* Fill in ICMP header */ icmp6.icmp6_type = ICMP6_DST_UNREACH; icmp6.icmp6_code = code; icmp6.icmp6_cksum = 0; /* Create pseudo header */ pseudo.length = htonl(icmp6_size + pseudo.length); pseudo.next = htonl(IPPROTO_ICMPV6); /* Generate checksum */ checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0); checksum = inet_checksum(&icmp6, icmp6_size, checksum); checksum = inet_checksum(packet->data + ether_size + ip6_size + icmp6_size, ntohl(pseudo.length) - icmp6_size, checksum); icmp6.icmp6_cksum = checksum; /* Copy structs on stack back to packet */ memcpy(packet->data + ether_size, &ip6, ip6_size); memcpy(packet->data + ether_size + ip6_size, &icmp6, icmp6_size); packet->len = ether_size + ip6_size + ntohl(pseudo.length); write_packet(packet); } static node_t *route_ipv6(vpn_packet_t *packet) { subnet_t *subnet; cp(); subnet = lookup_subnet_ipv6((ipv6_t *) &packet->data[38]); if(!subnet) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: unknown IPv6 destination address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx"), ntohs(*(uint16_t *) &packet->data[38]), ntohs(*(uint16_t *) &packet->data[40]), ntohs(*(uint16_t *) &packet->data[42]), ntohs(*(uint16_t *) &packet->data[44]), ntohs(*(uint16_t *) &packet->data[46]), ntohs(*(uint16_t *) &packet->data[48]), ntohs(*(uint16_t *) &packet->data[50]), ntohs(*(uint16_t *) &packet->data[52])); route_ipv6_unreachable(packet, ICMP6_DST_UNREACH_ADDR); return NULL; } if(!subnet->owner->status.reachable) route_ipv6_unreachable(packet, ICMP6_DST_UNREACH_NOROUTE); return subnet->owner; } /* RFC 2461 */ static void route_neighborsol(vpn_packet_t *packet) { struct ip6_hdr ip6; struct nd_neighbor_solicit ns; struct nd_opt_hdr opt; subnet_t *subnet; uint16_t checksum; struct { struct in6_addr ip6_src; /* source address */ struct in6_addr ip6_dst; /* destination address */ uint32_t length; uint32_t next; } pseudo; cp(); /* Copy headers from packet to structs on the stack */ memcpy(&ip6, packet->data + ether_size, ip6_size); memcpy(&ns, packet->data + ether_size + ip6_size, ns_size); memcpy(&opt, packet->data + ether_size + ip6_size + ns_size, opt_size); /* First, snatch the source address from the neighbor solicitation packet */ if(overwrite_mac) memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN); /* Check if this is a valid neighbor solicitation request */ if(ns.nd_ns_hdr.icmp6_type != ND_NEIGHBOR_SOLICIT || opt.nd_opt_type != ND_OPT_SOURCE_LINKADDR) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: received unknown type neighbor solicitation request")); return; } /* Create pseudo header */ memcpy(&pseudo.ip6_src, &ip6.ip6_src, sizeof(ip6.ip6_src)); memcpy(&pseudo.ip6_dst, &ip6.ip6_dst, sizeof(ip6.ip6_dst)); pseudo.length = htonl(ns_size + opt_size + ETH_ALEN); pseudo.next = htonl(IPPROTO_ICMPV6); /* Generate checksum */ checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0); checksum = inet_checksum(&ns, ns_size, checksum); checksum = inet_checksum(&opt, opt_size, checksum); if(checksum) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: checksum error for neighbor solicitation request")); return; } /* Check if the IPv6 address exists on the VPN */ subnet = lookup_subnet_ipv6((ipv6_t *) &ns.nd_ns_target); if(!subnet) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: neighbor solicitation request for unknown address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx"), ntohs(((uint16_t *) &ns.nd_ns_target)[0]), ntohs(((uint16_t *) &ns.nd_ns_target)[1]), ntohs(((uint16_t *) &ns.nd_ns_target)[2]), ntohs(((uint16_t *) &ns.nd_ns_target)[3]), ntohs(((uint16_t *) &ns.nd_ns_target)[4]), ntohs(((uint16_t *) &ns.nd_ns_target)[5]), ntohs(((uint16_t *) &ns.nd_ns_target)[6]), ntohs(((uint16_t *) &ns.nd_ns_target)[7])); return; } /* Check if it is for our own subnet */ if(subnet->owner == myself) return; /* silently ignore */ /* Create neighbor advertation reply */ memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN); /* copy destination address */ packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */ memcpy(&ip6.ip6_src, &ns.nd_ns_target, sizeof(ip6.ip6_src)); /* swap destination and source protocol address */ memcpy(&ip6.ip6_dst, &ip6.ip6_src, sizeof(ip6.ip6_dst)); /* ... */ memcpy(&opt + opt_size, packet->data + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */ ns.nd_ns_cksum = 0; ns.nd_ns_type = ND_NEIGHBOR_ADVERT; ns.nd_ns_reserved = htonl(0x40000000UL); /* Set solicited flag */ opt.nd_opt_type = ND_OPT_TARGET_LINKADDR; /* Create pseudo header */ memcpy(&pseudo.ip6_src, &ip6.ip6_src, sizeof(ip6.ip6_src)); memcpy(&pseudo.ip6_dst, &ip6.ip6_dst, sizeof(ip6.ip6_dst)); pseudo.length = htonl(ns_size + opt_size + ETH_ALEN); pseudo.next = htonl(IPPROTO_ICMPV6); /* Generate checksum */ checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0); checksum = inet_checksum(&ns, ns_size, checksum); checksum = inet_checksum(&opt, opt_size, checksum); ns.nd_ns_hdr.icmp6_cksum = checksum; /* Copy structs on stack back to packet */ memcpy(packet->data + ether_size, &ip6, ip6_size); memcpy(packet->data + ether_size + ip6_size, &ns, ns_size); memcpy(packet->data + ether_size + ip6_size + ns_size, &opt, opt_size); write_packet(packet); } /* RFC 826 */ static void route_arp(vpn_packet_t *packet) { struct ether_arp arp; subnet_t *subnet; struct in_addr addr; cp(); /* First, snatch the source address from the ARP packet */ if(overwrite_mac) memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN); /* Copy headers from packet to structs on the stack */ memcpy(&arp, packet->data + ether_size, arp_size); /* Check if this is a valid ARP request */ if(ntohs(arp.arp_hrd) != ARPHRD_ETHER || ntohs(arp.arp_pro) != ETH_P_IP || arp.arp_hln != ETH_ALEN || arp.arp_pln != sizeof(addr) || ntohs(arp.arp_op) != ARPOP_REQUEST) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: received unknown type ARP request")); return; } /* Check if the IPv4 address exists on the VPN */ subnet = lookup_subnet_ipv4((ipv4_t *) &arp.arp_tpa); if(!subnet) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: ARP request for unknown address %d.%d.%d.%d"), arp.arp_tpa[0], arp.arp_tpa[1], arp.arp_tpa[2], arp.arp_tpa[3]); return; } /* Check if it is for our own subnet */ if(subnet->owner == myself) return; /* silently ignore */ memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN); /* copy destination address */ packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */ memcpy(&addr, arp.arp_tpa, sizeof(addr)); /* save protocol addr */ memcpy(arp.arp_tpa, arp.arp_spa, sizeof(addr)); /* swap destination and source protocol address */ memcpy(arp.arp_spa, &addr, sizeof(addr)); /* ... */ memcpy(arp.arp_tha, arp.arp_sha, ETH_ALEN); /* set target hard/proto addr */ memcpy(arp.arp_sha, packet->data + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */ arp.arp_op = htons(ARPOP_REPLY); /* Copy structs on stack back to packet */ memcpy(packet->data + ether_size, &arp, arp_size); write_packet(packet); } void route_outgoing(vpn_packet_t *packet) { uint16_t type; node_t *n = NULL; cp(); if(packet->len < ether_size) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet")); return; } /* FIXME: multicast? */ switch (routing_mode) { case RMODE_ROUTER: type = ntohs(*((uint16_t *)(&packet->data[12]))); switch (type) { case ETH_P_IP: if(packet->len < ether_size + ip_size) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet")); return; } n = route_ipv4(packet); break; case ETH_P_IPV6: if(packet->len < ether_size + ip6_size) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet")); return; } if(packet->data[20] == IPPROTO_ICMPV6 && packet->len >= ether_size + ip6_size + ns_size && packet->data[54] == ND_NEIGHBOR_SOLICIT) { route_neighborsol(packet); return; } n = route_ipv6(packet); break; case ETH_P_ARP: if(packet->len < ether_size + arp_size) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet")); return; } route_arp(packet); return; default: ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: unknown type %hx"), type); return; } if(n) send_packet(n, packet); break; case RMODE_SWITCH: n = route_mac(packet); if(n) send_packet(n, packet); else broadcast_packet(myself, packet); break; case RMODE_HUB: broadcast_packet(myself, packet); break; } } void route_incoming(node_t *source, vpn_packet_t *packet) { if(packet->len < ether_size) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet")); return; } switch (routing_mode) { case RMODE_ROUTER: { node_t *n = NULL; uint16_t type; type = ntohs(*((uint16_t *)(&packet->data[12]))); switch (type) { case ETH_P_IP: if(packet->len < ether_size + ip_size) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet")); return; } n = route_ipv4(packet); break; case ETH_P_IPV6: if(packet->len < ether_size + ip6_size) { ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet")); return; } n = route_ipv6(packet); break; default: n = myself; break; } if(n) { if(n == myself) { if(overwrite_mac) memcpy(packet->data, mymac.x, ETH_ALEN); write_packet(packet); } else send_packet(n, packet); } } break; case RMODE_SWITCH: { subnet_t *subnet; subnet = lookup_subnet_mac((mac_t *)(&packet->data[0])); if(subnet) { if(subnet->owner == myself) write_packet(packet); else send_packet(subnet->owner, packet); } else { broadcast_packet(source, packet); write_packet(packet); } } break; case RMODE_HUB: broadcast_packet(source, packet); /* Spread it on */ write_packet(packet); break; } }