+ 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;