Fix DecrementTTL option for packets destined to the local node.

[tinc] / src / route.c

diff --git a/src/route.c b/src/route.c
index 3d7b1df..6415f0e 100644 (file)
--- a/src/route.c
+++ b/src/route.c
@@ -55,6 +55,8 @@ 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
@@ -250,6 +252,14 @@ static void learn_mac(mac_t *address) {
        }
 }
 
+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) {
@@ -259,7 +269,6 @@ 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;
@@ -279,21 +288,23 @@ 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;
@@ -418,7 +429,7 @@ static void route_ipv4(node_t *source, vpn_packet_t *packet) {
        }
 
        if (!subnet->owner) {
-               broadcast_packet(source, packet);
+               broadcast_packet_helper(source, packet);
                return;
        }
 
@@ -433,6 +444,10 @@ static void route_ipv4(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 = DATA(packet)[15];
 
@@ -469,7 +484,6 @@ 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 */
@@ -496,21 +510,23 @@ 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;
@@ -598,7 +614,7 @@ static void route_ipv6(node_t *source, vpn_packet_t *packet) {
        }
 
        if (!subnet->owner) {
-               broadcast_packet(source, packet);
+               broadcast_packet_helper(source, packet);
                return;
        }
 
@@ -613,6 +629,10 @@ static void route_ipv6(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) {
@@ -729,6 +749,10 @@ 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(DATA(packet), DATA(packet) + ETH_ALEN, ETH_ALEN); /* copy destination address */
@@ -824,6 +848,10 @@ 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(&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);                 /* ... */
@@ -858,7 +886,7 @@ static void route_mac(node_t *source, vpn_packet_t *packet) {
        subnet = lookup_subnet_mac(NULL, &dest);
 
        if(!subnet || !subnet->owner) {
-               broadcast_packet(source, packet);
+               broadcast_packet_helper(source, packet);
                return;
        }
 
@@ -870,6 +898,10 @@ 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 = DATA(packet)[12] << 8 | DATA(packet)[13];
 
        if(priorityinheritance && type == ETH_P_IP && packet->len >= ether_size + ip_size)
@@ -992,10 +1024,6 @@ 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;
-
        uint16_t type = DATA(packet)[12] << 8 | DATA(packet)[13];
 
        switch (routing_mode) {
@@ -1024,7 +1052,7 @@ void route(node_t *source, vpn_packet_t *packet) {
                        break;
 
                case RMODE_HUB:
-                       broadcast_packet(source, packet);
+                       broadcast_packet_helper(source, packet);
                        break;
        }
 }