Fix DecrementTTL option for packets destined to the local node.

[oweals/tinc.git] / src / route.c

diff --git a/src/route.c b/src/route.c
index f046e6e4abb161871511eef014a1fc7a818c3521..1b539aa1df60cbb6b89838ac3686069f88433428 100644 (file)
--- a/src/route.c
+++ b/src/route.c
@@ -53,6 +53,8 @@ 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);
 
+static bool do_decrement_ttl(node_t *source, vpn_packet_t *packet);
+
 #ifndef MAX
 #define MAX(a, b) ((a) > (b) ? (a) : (b))
 #endif
@@ -160,7 +162,7 @@ static void clamp_mss(const node_t *source, const node_t *via, vpn_packet_t *pac
                /* Found it */
                uint16_t oldmss = packet->data[start + 22 + i] << 8 | packet->data[start + 23 + i];
                uint16_t newmss = mtu - start - 20;
-               uint16_t csum = packet->data[start + 16] << 8 | packet->data[start + 17];
+               uint32_t csum = packet->data[start + 16] << 8 | packet->data[start + 17];
 
                if(oldmss <= newmss)
                        break;
@@ -171,11 +173,13 @@ static void clamp_mss(const node_t *source, const node_t *via, vpn_packet_t *pac
                packet->data[start + 22 + i] = newmss >> 8;
                packet->data[start + 23 + i] = newmss & 0xff;
                csum ^= 0xffff;
-               csum -= oldmss;
+               csum += oldmss ^ 0xffff;
                csum += newmss;
+               csum = (csum & 0xffff) + (csum >> 16);
+               csum += csum >> 16;
                csum ^= 0xffff;
                packet->data[start + 16] = csum >> 8;
-               packet->data[start + 17] = csum & 0xff;
+               packet->data[start + 17] = csum;
                break;
        }
 }
@@ -249,6 +253,14 @@ void age_subnets(void) {
        }
 }
 
+static void broadcast_packet_helper(node_t *source, vpn_packet_t *packet) {
+       if(decrement_ttl && source != myself)
+               if(!do_decrement_ttl(source, packet))
+                       return;
+
+       broadcast_packet(source, packet);
+}
+
 /* RFC 792 */
 
 static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, length_t ether_size, uint8_t type, uint8_t code) {
@@ -258,7 +270,6 @@ static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, length_
        struct in_addr ip_src;
        struct in_addr ip_dst;
        uint32_t oldlen;
-       int sockfd;
 
        if(ratelimit(3))
                return;
@@ -278,21 +289,23 @@ static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, length_
 
        /* Try to reply with an IP address assigned to the local machine */
 
-       sockfd = socket(AF_INET, SOCK_DGRAM, 0);
-       if (sockfd != -1) {
-               struct sockaddr_in addr;
-               memset(&addr, 0, sizeof(addr));
-               addr.sin_family = AF_INET;
-               addr.sin_addr = ip.ip_src;
-               if (!connect(sockfd, (const struct sockaddr*) &addr, sizeof(addr))) {
+       if (type == ICMP_TIME_EXCEEDED && code == ICMP_EXC_TTL) {
+               int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+               if (sockfd != -1) {
+                       struct sockaddr_in addr;
                        memset(&addr, 0, sizeof(addr));
                        addr.sin_family = AF_INET;
-                       socklen_t addrlen = sizeof(addr);
-                       if (!getsockname(sockfd, (struct sockaddr*) &addr, &addrlen) && addrlen <= sizeof(addr)) {
-                               ip_dst = addr.sin_addr;
+                       addr.sin_addr = ip.ip_src;
+                       if (!connect(sockfd, (const struct sockaddr*) &addr, sizeof(addr))) {
+                               memset(&addr, 0, sizeof(addr));
+                               addr.sin_family = AF_INET;
+                               socklen_t addrlen = sizeof(addr);
+                               if (!getsockname(sockfd, (struct sockaddr*) &addr, &addrlen) && addrlen <= sizeof(addr)) {
+                                       ip_dst = addr.sin_addr;
+                               }
                        }
+                       close(sockfd);
                }
-               close(sockfd);
        }
 
        oldlen = packet->len - ether_size;
@@ -423,6 +436,10 @@ static void route_ipv4_unicast(node_t *source, vpn_packet_t *packet) {
        if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
                return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_ANO);
 
+       if(decrement_ttl && source != myself && subnet->owner != myself)
+               if(!do_decrement_ttl(source, packet))
+                       return;
+
        if(priorityinheritance)
                packet->priority = packet->data[15];
 
@@ -462,7 +479,7 @@ static void route_ipv4(node_t *source, vpn_packet_t *packet) {
                        packet->data[31] == 255 &&
                        packet->data[32] == 255 &&
                        packet->data[33] == 255)))
-               broadcast_packet(source, packet);
+               broadcast_packet_helper(source, packet);
        else
                route_ipv4_unicast(source, packet);
 }
@@ -473,7 +490,6 @@ static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, length_
        struct ip6_hdr ip6;
        struct icmp6_hdr icmp6 = {0};
        uint16_t checksum;      
-       int sockfd;
 
        struct {
                struct in6_addr ip6_src;        /* source address */
@@ -500,21 +516,23 @@ static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, length_
 
        /* Try to reply with an IP address assigned to the local machine */
 
-       sockfd = socket(AF_INET6, SOCK_DGRAM, 0);
-       if (sockfd != -1) {
-               struct sockaddr_in6 addr;
-               memset(&addr, 0, sizeof(addr));
-               addr.sin6_family = AF_INET6;
-               addr.sin6_addr = ip6.ip6_src;
-               if (!connect(sockfd, (const struct sockaddr*) &addr, sizeof(addr))) {
+       if (type == ICMP6_TIME_EXCEEDED && code == ICMP6_TIME_EXCEED_TRANSIT) {
+               int sockfd = socket(AF_INET6, SOCK_DGRAM, 0);
+               if (sockfd != -1) {
+                       struct sockaddr_in6 addr;
                        memset(&addr, 0, sizeof(addr));
                        addr.sin6_family = AF_INET6;
-                       socklen_t addrlen = sizeof(addr);
-                       if (!getsockname(sockfd, (struct sockaddr*) &addr, &addrlen) && addrlen <= sizeof(addr)) {
-                               pseudo.ip6_src = addr.sin6_addr;
+                       addr.sin6_addr = ip6.ip6_src;
+                       if (!connect(sockfd, (const struct sockaddr*) &addr, sizeof(addr))) {
+                               memset(&addr, 0, sizeof(addr));
+                               addr.sin6_family = AF_INET6;
+                               socklen_t addrlen = sizeof(addr);
+                               if (!getsockname(sockfd, (struct sockaddr*) &addr, &addrlen) && addrlen <= sizeof(addr)) {
+                                       pseudo.ip6_src = addr.sin6_addr;
+                               }
                        }
+                       close(sockfd);
                }
-               close(sockfd);
        }
 
        pseudo.length = packet->len - ether_size;
@@ -602,6 +620,10 @@ static void route_ipv6_unicast(node_t *source, vpn_packet_t *packet) {
        if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
                return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADMIN);
 
+       if(decrement_ttl && source != myself && subnet->owner != myself)
+               if(!do_decrement_ttl(source, packet))
+                       return;
+
        via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
        
        if(via == source) {
@@ -718,6 +740,10 @@ static void route_neighborsol(node_t *source, vpn_packet_t *packet) {
        if(subnet->owner == myself)
                return;                                 /* silently ignore */
 
+       if(decrement_ttl)
+               if(!do_decrement_ttl(source, packet))
+                       return;
+
        /* Create neighbor advertation reply */
 
        memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN);        /* copy destination address */
@@ -775,7 +801,7 @@ static void route_ipv6(node_t *source, vpn_packet_t *packet) {
        }
 
        if(broadcast_mode && packet->data[38] == 255)
-               broadcast_packet(source, packet);
+               broadcast_packet_helper(source, packet);
        else
                route_ipv6_unicast(source, packet);
 }
@@ -828,6 +854,10 @@ static void route_arp(node_t *source, vpn_packet_t *packet) {
        if(subnet->owner == myself)
                return;                                 /* silently ignore */
 
+       if(decrement_ttl)
+               if(!do_decrement_ttl(source, packet))
+                       return;
+
        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 */
 
@@ -864,7 +894,7 @@ static void route_mac(node_t *source, vpn_packet_t *packet) {
        subnet = lookup_subnet_mac(NULL, &dest);
 
        if(!subnet) {
-               broadcast_packet(source, packet);
+               broadcast_packet_helper(source, packet);
                return;
        }
 
@@ -876,6 +906,10 @@ static void route_mac(node_t *source, vpn_packet_t *packet) {
        if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
                return;
 
+       if(decrement_ttl && source != myself && subnet->owner != myself)
+               if(!do_decrement_ttl(source, packet))
+                       return;
+
        uint16_t type = packet->data[12] << 8 | packet->data[13];
 
        if(priorityinheritance && type == ETH_P_IP && packet->len >= ether_size + ip_size)
@@ -978,10 +1012,6 @@ void route(node_t *source, vpn_packet_t *packet) {
        if(!checklength(source, packet, ether_size))
                return;
 
-       if(decrement_ttl && source != myself)
-               if(!do_decrement_ttl(source, packet))
-                       return;
-
        switch (routing_mode) {
                case RMODE_ROUTER:
                        {
@@ -1012,7 +1042,7 @@ void route(node_t *source, vpn_packet_t *packet) {
                        break;
 
                case RMODE_HUB:
-                       broadcast_packet(source, packet);
+                       broadcast_packet_helper(source, packet);
                        break;
        }
 }