]> git.meshlink.io Git - meshlink/commitdiff
Copy structs from packets to the stack before using them, to prevent
authorGuus Sliepen <guus@tinc-vpn.org>
Mon, 6 Oct 2003 13:49:57 +0000 (13:49 +0000)
committerGuus Sliepen <guus@tinc-vpn.org>
Mon, 6 Oct 2003 13:49:57 +0000 (13:49 +0000)
alignment issues.

src/route.c

index e9e07f67263a2d39cbe468e06ae576ea516926f6..d38b08e4be89fb49979bf2e6b20a478776fce302 100644 (file)
@@ -17,7 +17,7 @@
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
-    $Id: route.c,v 1.1.2.66 2003/10/01 09:14:01 guus Exp $
+    $Id: route.c,v 1.1.2.67 2003/10/06 13:49:57 guus Exp $
 */
 
 #include "system.h"
@@ -57,6 +57,17 @@ int macexpire = 600;
 bool overwrite_mac = false;
 mac_t mymac = {{0xFE, 0xFD, 0, 0, 0, 0}};
 
+/* Sizes of various headers */
+
+static size_t ether_size = sizeof(struct ether_header);
+static size_t arp_size = sizeof(struct ether_arp);
+static size_t ip_size = sizeof(struct ip);
+static size_t icmp_size = sizeof(struct icmp) - sizeof(struct ip);
+static size_t ip6_size = sizeof(struct ip6_hdr);
+static size_t icmp6_size = sizeof(struct icmp6_hdr);
+static size_t ns_size = sizeof(struct nd_neighbor_solicit);
+static size_t opt_size = sizeof(struct nd_opt_hdr);
+
 /* RFC 1071 */
 
 static uint16_t inet_checksum(void *data, int len, uint16_t prevsum)
@@ -78,13 +89,18 @@ static uint16_t inet_checksum(void *data, int len, uint16_t prevsum)
        return ~checksum;
 }
 
-static bool ratelimit(void) {
+static bool ratelimit(int frequency) {
        static time_t lasttime = 0;
+       static int count = 0;
        
-       if(lasttime == now)
-               return true;
+       if(lasttime == now) {
+               if(++count > frequency)
+                       return true;
+       } else {
+               lasttime = now;
+               count = 0;
+       }
 
-       lasttime = now;
        return false;
 }
        
@@ -174,59 +190,68 @@ static node_t *route_mac(vpn_packet_t *packet)
 
 static void route_ipv4_unreachable(vpn_packet_t *packet, uint8_t code)
 {
-       struct ip *hdr;
-       struct icmp *icmp;
+       struct ip ip;
+       struct icmp icmp;
        
        struct in_addr ip_src;
        struct in_addr ip_dst;
        uint32_t oldlen;
 
-       if(ratelimit())
+       if(ratelimit(3))
                return;
        
        cp();
 
-       hdr = (struct ip *)(packet->data + 14);
-       icmp = (struct icmp *)(packet->data + 14 + 20);
+       /* 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, &hdr->ip_src, 4);
-       memcpy(&ip_dst, &hdr->ip_dst, 4);
-       oldlen = packet->len - 14;
+       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 - sizeof(*hdr) - sizeof(*icmp))
-               oldlen = IP_MSS - sizeof(*hdr) - sizeof(*icmp);
+       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(&icmp->icmp_ip, hdr, oldlen);
+       memmove(packet->data + ether_size + ip_size + icmp_size, packet->data + ether_size, oldlen);
 
        /* Fill in IPv4 header */
        
-       hdr->ip_v = 4;
-       hdr->ip_hl = sizeof(*hdr) / 4;
-       hdr->ip_tos = 0;
-       hdr->ip_len = htons(20 + 8 + oldlen);
-       hdr->ip_id = 0;
-       hdr->ip_off = 0;
-       hdr->ip_ttl = 255;
-       hdr->ip_p = IPPROTO_ICMP;
-       hdr->ip_sum = 0;
-       memcpy(&hdr->ip_src, &ip_dst, 4);
-       memcpy(&hdr->ip_dst, &ip_src, 4);
-
-       hdr->ip_sum = inet_checksum(hdr, 20, ~0);
+       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_type = ICMP_DEST_UNREACH;
+       icmp.icmp_code = code;
+       icmp.icmp_cksum = 0;
        
-       icmp->icmp_cksum = inet_checksum(icmp, 8 + oldlen, ~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 = 14 + 20 + 8 + oldlen;
+       packet->len = ether_size + ip_size + icmp_size + oldlen;
        
        write_packet(packet);
 }
@@ -261,8 +286,8 @@ static node_t *route_ipv4(vpn_packet_t *packet)
 
 static void route_ipv6_unreachable(vpn_packet_t *packet, uint8_t code)
 {
-       struct ip6_hdr *hdr;
-       struct icmp6_hdr *icmp;
+       struct ip6_hdr ip6;
+       struct icmp6_hdr icmp6;
        uint16_t checksum;      
 
        struct {
@@ -272,55 +297,64 @@ static void route_ipv6_unreachable(vpn_packet_t *packet, uint8_t code)
                uint32_t next;
        } pseudo;
 
-       if(ratelimit())
+       if(ratelimit(3))
                return;
        
        cp();
 
-       hdr = (struct ip6_hdr *)(packet->data + 14);
-       icmp = (struct icmp6_hdr *)(packet->data + 14 + sizeof(*hdr));
+       /* 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, &hdr->ip6_dst, 16);
-       memcpy(&pseudo.ip6_dst, &hdr->ip6_src, 16);
-       pseudo.length = ntohs(hdr->ip6_plen) + sizeof(*hdr);
+       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 - sizeof(*hdr) - sizeof(*icmp))
-               pseudo.length = IP_MSS - sizeof(*hdr) - sizeof(*icmp);
+       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(((char *)icmp) + sizeof(*icmp), hdr, pseudo.length);
+       memmove(packet->data + ether_size + ip6_size + icmp6_size, packet->data + ether_size, pseudo.length);
 
        /* Fill in IPv6 header */
        
-       hdr->ip6_flow = htonl(0x60000000UL);
-       hdr->ip6_plen = htons(sizeof(*icmp) + pseudo.length);
-       hdr->ip6_nxt = IPPROTO_ICMPV6;
-       hdr->ip6_hlim = 255;
-       memcpy(&hdr->ip6_dst, &pseudo.ip6_dst, 16);
-       memcpy(&hdr->ip6_src, &pseudo.ip6_src, 16);
+       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 */
        
-       icmp->icmp6_type = ICMP6_DST_UNREACH;
-       icmp->icmp6_code = code;
-       icmp->icmp6_cksum = 0;
+       icmp6.icmp6_type = ICMP6_DST_UNREACH;
+       icmp6.icmp6_code = code;
+       icmp6.icmp6_cksum = 0;
 
        /* Create pseudo header */
                
-       pseudo.length = htonl(sizeof(*icmp) + pseudo.length);
+       pseudo.length = htonl(icmp6_size + pseudo.length);
        pseudo.next = htonl(IPPROTO_ICMPV6);
 
        /* Generate checksum */
        
        checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
-       checksum = inet_checksum(icmp, ntohl(pseudo.length), checksum);
+       checksum = inet_checksum(&icmp6, icmp6_size, checksum);
+       checksum = inet_checksum(packet->data + ether_size + ip6_size + icmp6_size, ntohl(pseudo.length) - icmp6_size, checksum);
 
-       icmp->icmp6_cksum = 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 = 14 + sizeof(*hdr) + ntohl(pseudo.length);
+       packet->len = ether_size + ip6_size + ntohl(pseudo.length);
        
        write_packet(packet);
 }
@@ -358,9 +392,9 @@ static node_t *route_ipv6(vpn_packet_t *packet)
 
 static void route_neighborsol(vpn_packet_t *packet)
 {
-       struct ip6_hdr *hdr;
-       struct nd_neighbor_solicit *ns;
-       struct nd_opt_hdr *opt;
+       struct ip6_hdr ip6;
+       struct nd_neighbor_solicit ns;
+       struct nd_opt_hdr opt;
        subnet_t *subnet;
        uint16_t checksum;
 
@@ -373,34 +407,37 @@ static void route_neighborsol(vpn_packet_t *packet)
 
        cp();
 
-       hdr = (struct ip6_hdr *)(packet->data + 14);
-       ns = (struct nd_neighbor_solicit *)(packet->data + 14 + sizeof(*hdr));
-       opt = (struct nd_opt_hdr *)(packet->data + 14 + sizeof(*hdr) + sizeof(*ns));
+       /* 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 + 6, 6);
+               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) {
+       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, &hdr->ip6_src, 16);
-       memcpy(&pseudo.ip6_dst, &hdr->ip6_dst, 16);
-       pseudo.length = htonl(sizeof(*ns) + sizeof(*opt) + 6);
+       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, sizeof(*ns) + 8, checksum);
+       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"));
@@ -409,18 +446,18 @@ static void route_neighborsol(vpn_packet_t *packet)
 
        /* Check if the IPv6 address exists on the VPN */
 
-       subnet = lookup_subnet_ipv6((ipv6_t *) &ns->nd_ns_target);
+       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]));
+                                  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;
        }
@@ -432,35 +469,39 @@ static void route_neighborsol(vpn_packet_t *packet)
 
        /* Create neighbor advertation reply */
 
-       memcpy(packet->data, packet->data + ETHER_ADDR_LEN, ETHER_ADDR_LEN);    /* copy destination address */
-       packet->data[ETHER_ADDR_LEN * 2 - 1] ^= 0xFF;   /* mangle source address so it looks like it's not from us */
+       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(&hdr->ip6_dst, &hdr->ip6_src, 16);       /* swap destination and source protocol address */
-       memcpy(&hdr->ip6_src, &ns->nd_ns_target, 16);   /* ... */
+       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((char *) opt + sizeof(*opt), packet->data + ETHER_ADDR_LEN, 6);  /* add fake source hard addr */
+       memcpy(&opt + opt_size, packet->data + ETH_ALEN, ETH_ALEN);     /* add fake source hard addr */
 
-       ns->nd_ns_hdr.icmp6_cksum = 0;
-       ns->nd_ns_hdr.icmp6_type = ND_NEIGHBOR_ADVERT;
-       ns->nd_ns_hdr.icmp6_dataun.icmp6_un_data8[0] = 0x40;    /* Set solicited flag */
-       ns->nd_ns_hdr.icmp6_dataun.icmp6_un_data8[1] =
-               ns->nd_ns_hdr.icmp6_dataun.icmp6_un_data8[2] =
-               ns->nd_ns_hdr.icmp6_dataun.icmp6_un_data8[3] = 0;
-       opt->nd_opt_type = ND_OPT_TARGET_LINKADDR;
+       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, &hdr->ip6_src, 16);
-       memcpy(&pseudo.ip6_dst, &hdr->ip6_dst, 16);
-       pseudo.length = htonl(sizeof(*ns) + sizeof(*opt) + 6);
+       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, sizeof(*ns) + 8, checksum);
+       checksum = inet_checksum(&ns, ns_size, checksum);
+       checksum = inet_checksum(&opt, opt_size, checksum);
+
+       ns.nd_ns_hdr.icmp6_cksum = 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);
 }
@@ -469,40 +510,37 @@ static void route_neighborsol(vpn_packet_t *packet)
 
 static void route_arp(vpn_packet_t *packet)
 {
-       struct ether_arp *arp;
+       struct ether_arp arp;
        subnet_t *subnet;
-       uint8_t ipbuf[4];
+       struct in_addr addr;
 
        cp();
 
        /* First, snatch the source address from the ARP packet */
 
        if(overwrite_mac)
-               memcpy(mymac.x, packet->data + 6, 6);
+               memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN);
 
-       /* This routine generates replies to ARP requests.
-          You don't need to set NOARP flag on the interface anymore (which is broken on FreeBSD).
-          Most of the code here is taken from choparp.c by Takamichi Tateoka (tree@mma.club.uec.ac.jp)
-        */
+       /* Copy headers from packet to structs on the stack */
 
-       arp = (struct ether_arp *)(packet->data + 14);
+       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) != ETHERTYPE_IP ||
-          arp->arp_hln != ETHER_ADDR_LEN || arp->arp_pln != 4 || ntohs(arp->arp_op) != ARPOP_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);
+       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]);
+                                  arp.arp_tpa[0], arp.arp_tpa[1], arp.arp_tpa[2],
+                                  arp.arp_tpa[3]);
                return;
        }
 
@@ -511,16 +549,20 @@ static void route_arp(vpn_packet_t *packet)
        if(subnet->owner == myself)
                return;                                 /* silently ignore */
 
-       memcpy(packet->data, packet->data + ETHER_ADDR_LEN, ETHER_ADDR_LEN);    /* copy destination address */
-       packet->data[ETHER_ADDR_LEN * 2 - 1] ^= 0xFF;   /* mangle source address so it looks like it's not from us */
+       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(ipbuf, arp->arp_tpa, 4); /* save protocol addr */
-       memcpy(arp->arp_tpa, arp->arp_spa, 4);  /* swap destination and source protocol address */
-       memcpy(arp->arp_spa, ipbuf, 4); /* ... */
+       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);
 
-       memcpy(arp->arp_tha, arp->arp_sha, 10); /* set target hard/proto addr */
-       memcpy(arp->arp_sha, packet->data + ETHER_ADDR_LEN, ETHER_ADDR_LEN);    /* 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);
 }
@@ -532,7 +574,7 @@ void route_outgoing(vpn_packet_t *packet)
 
        cp();
 
-       if(packet->len < 14) {
+       if(packet->len < ether_size) {
                ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet"));
                return;
        }
@@ -543,8 +585,8 @@ void route_outgoing(vpn_packet_t *packet)
                case RMODE_ROUTER:
                        type = ntohs(*((uint16_t *)(&packet->data[12])));
                        switch (type) {
-                               case 0x0800:
-                                       if(packet->len < 34) {
+                               case ETH_P_IP:
+                                       if(packet->len < ether_size + ip_size) {
                                                ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet"));
                                                return;
                                        }
@@ -552,21 +594,21 @@ void route_outgoing(vpn_packet_t *packet)
                                        n = route_ipv4(packet);
                                        break;
 
-                               case 0x86DD:
-                                       if(packet->len < 54) {
+                               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 >= 62 && packet->data[54] == ND_NEIGHBOR_SOLICIT) {
+                                       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 0x0806:
-                                       if(packet->len < 42) {
+                               case ETH_P_ARP:
+                                       if(packet->len < ether_size + arp_size) {
                                                ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet"));
                                                return;
                                        }
@@ -598,9 +640,8 @@ void route_outgoing(vpn_packet_t *packet)
 
 void route_incoming(node_t *source, vpn_packet_t *packet)
 {
-       if(packet->len < 14) {
-               ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got too short packet from %s (%s)"),
-                                       source->name, source->hostname);
+       if(packet->len < ether_size) {
+               ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet"));
                return;
        }
 
@@ -612,8 +653,8 @@ void route_incoming(node_t *source, vpn_packet_t *packet)
 
                                type = ntohs(*((uint16_t *)(&packet->data[12])));
                                switch (type) {
-                                       case 0x0800:
-                                               if(packet->len < 34) {
+                                       case ETH_P_IP:
+                                               if(packet->len < ether_size + ip_size) {
                                                        ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet"));
                                                        return;
                                                }
@@ -621,8 +662,8 @@ void route_incoming(node_t *source, vpn_packet_t *packet)
                                                n = route_ipv4(packet);
                                                break;
 
-                                       case 0x86DD:
-                                               if(packet->len < 54) {
+                                       case ETH_P_IPV6:
+                                               if(packet->len < ether_size + ip6_size) {
                                                        ifdebug(TRAFFIC) logger(LOG_WARNING, _("Read too short packet"));
                                                        return;
                                                }
@@ -638,7 +679,7 @@ void route_incoming(node_t *source, vpn_packet_t *packet)
                                if(n) {
                                        if(n == myself) {
                                                if(overwrite_mac)
-                                                       memcpy(packet->data, mymac.x, 6);
+                                                       memcpy(packet->data, mymac.x, ETH_ALEN);
                                                write_packet(packet);
                                        } else
                                                send_packet(n, packet);