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Improvements for PMTU discovery and IPv4 packet fragmentation.

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This commit is contained in:
Guus Sliepen 2003-12-22 11:04:17 +00:00
parent 6d41b429a2
commit 35399784b6
7 changed files with 111 additions and 38 deletions
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73
src/route.c
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@ -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 1.1.2.73 2003/12/20 21:25:17 guus Exp $
$Id: route.c,v 1.1.2.74 2003/12/22 11:04:17 guus Exp $
*/
#include "system.h"
@ -276,6 +276,58 @@ static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, uint8_t
send_packet(source, packet);
}
/* RFC 791 */
static __inline__ void fragment_ipv4_packet(node_t *dest, vpn_packet_t *packet) {
struct ip ip;
vpn_packet_t fragment;
int len, maxlen, todo;
uint8_t *offset;
uint16_t ip_off, origf;
cp();
memcpy(&ip, packet->data + ether_size, ip_size);
fragment.priority = packet->priority;
if(ip.ip_hl != ip_size / 4)
return;
todo = ntohs(ip.ip_len) - ip_size;
if(ether_size + ip_size + todo != packet->len) {
ifdebug(TRAFFIC) logger(LOG_WARNING, _("Length of packet (%d) doesn't match length in IPv4 header (%d)"), packet->len, ether_size + ip_size + todo);
return;
}
ifdebug(TRAFFIC) logger(LOG_INFO, _("Fragmenting packet of %d bytes to %s (%s)"), packet->len, dest->name, dest->hostname);
offset = packet->data + ether_size + ip_size;
maxlen = (dest->mtu - ether_size - ip_size) & ~0x7;
ip_off = ntohs(ip.ip_off);
origf = ip_off & ~IP_OFFMASK;
ip_off &= IP_OFFMASK;
while(todo) {
len = todo > maxlen ? maxlen : todo;
memcpy(fragment.data + ether_size + ip_size, offset, len);
todo -= len;
offset += len;
ip.ip_len = htons(ip_size + len);
ip.ip_off = htons(ip_off | origf | (todo ? IP_MF : 0));
ip.ip_sum = 0;
ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
memcpy(fragment.data, packet->data, ether_size);
memcpy(fragment.data + ether_size, &ip, ip_size);
fragment.len = ether_size + ip_size + len;
send_packet(dest, &fragment);
ip_off += len / 8;
}
}
static __inline__ void route_ipv4_unicast(node_t *source, vpn_packet_t *packet)
{
subnet_t *subnet;
@ -304,16 +356,21 @@ static __inline__ void route_ipv4_unicast(node_t *source, vpn_packet_t *packet)
if(!subnet->owner->status.reachable)
route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_NET_UNREACH);
if(subnet->owner->options & OPTION_PMTU_DISCOVERY && packet->len > subnet->owner->mtu && subnet->owner != myself) {
ifdebug(TRAFFIC) logger(LOG_INFO, _("Packet for %s (%s) length %d larger than MTU %d"), subnet->owner->name, subnet->owner->hostname, packet->len, subnet->owner->mtu);
packet->len = subnet->owner->mtu;
route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
return;
}
if(priorityinheritance)
packet->priority = packet->data[15];
if(subnet->owner->options & OPTION_PMTU_DISCOVERY && packet->len > subnet->owner->mtu && subnet->owner != myself) {
ifdebug(TRAFFIC) logger(LOG_INFO, _("Packet for %s (%s) length %d larger than MTU %d"), subnet->owner->name, subnet->owner->hostname, packet->len, subnet->owner->mtu);
if(packet->data[20] & 0x40) {
packet->len = subnet->owner->mtu;
route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
} else {
fragment_ipv4_packet(subnet->owner, packet);
}
return;
}
send_packet(subnet->owner, packet);
}