Forward packets to not directly reachable hosts via UDP if possible.

[tinc] / src / net_packet.c

diff --git a/src/net_packet.c b/src/net_packet.c
index 63e3592..054a66f 100644 (file)
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -58,31 +58,61 @@ static void send_udppacket(node_t *, vpn_packet_t *);
 
 #define MAX_SEQNO 1073741824
 
+// mtuprobes == 1..30: initial discovery, send bursts with 1 second interval
+// mtuprobes ==    31: sleep pinginterval seconds
+// mtuprobes ==    32: send 1 burst, sleep pingtimeout second
+// mtuprobes ==    33: no response from other side, restart PMTU discovery process
+
 void send_mtu_probe(node_t *n) {
        vpn_packet_t packet;
        int len, i;
+       int timeout = 1;
        
        n->mtuprobes++;
        n->mtuevent = NULL;
 
-       if(!n->status.reachable) {
-               logger(LOG_DEBUG, "Trying to send MTU probe to unreachable node %s (%s)", n->name, n->hostname);
+       if(!n->status.reachable || !n->status.validkey) {
+               ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send MTU probe to unreachable or rekeying node %s (%s)", n->name, n->hostname);
+               n->mtuprobes = 0;
                return;
        }
 
+       if(n->mtuprobes > 32) {
+               ifdebug(TRAFFIC) logger(LOG_INFO, "%s (%s) did not respond to UDP ping, restarting PMTU discovery", n->name, n->hostname);
+               n->mtuprobes = 1;
+               n->minmtu = 0;
+               n->maxmtu = MTU;
+       }
+
        if(n->mtuprobes >= 10 && !n->minmtu) {
                ifdebug(TRAFFIC) logger(LOG_INFO, "No response to MTU probes from %s (%s)", n->name, n->hostname);
+               n->mtuprobes = 0;
                return;
        }
 
+       if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) {
+               if(n->minmtu > n->maxmtu)
+                       n->minmtu = n->maxmtu;
+               else
+                       n->maxmtu = n->minmtu;
+               n->mtu = n->minmtu;
+               ifdebug(TRAFFIC) logger(LOG_INFO, "Fixing MTU of %s (%s) to %d after %d probes", n->name, n->hostname, n->mtu, n->mtuprobes);
+               n->mtuprobes = 31;
+       }
+
+       if(n->mtuprobes == 31) {
+               timeout = pinginterval;
+               goto end;
+       } else if(n->mtuprobes == 32) {
+               timeout = pingtimeout;
+       }
+
        for(i = 0; i < 3; i++) {
-               if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) {
-                       n->mtu = n->minmtu;
-                       ifdebug(TRAFFIC) logger(LOG_INFO, "Fixing MTU of %s (%s) to %d after %d probes", n->name, n->hostname, n->mtu, n->mtuprobes);
-                       return;
-               }
+               if(n->maxmtu <= n->minmtu)
+                       len = n->maxmtu;
+               else
+                       len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
 
-               len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
                if(len < 64)
                        len = 64;
                
@@ -96,10 +126,11 @@ void send_mtu_probe(node_t *n) {
                send_udppacket(n, &packet);
        }
 
+end:
        n->mtuevent = new_event();
        n->mtuevent->handler = (event_handler_t)send_mtu_probe;
        n->mtuevent->data = n;
-       n->mtuevent->time = now + 1;
+       n->mtuevent->time = now + timeout;
        event_add(n->mtuevent);
 }
 
@@ -108,10 +139,14 @@ void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 
        if(!packet->data[0]) {
                packet->data[0] = 1;
-               send_packet(n, packet);
+               send_udppacket(n, packet);
        } else {
+               if(len > n->maxmtu)
+                       len = n->maxmtu;
                if(n->minmtu < len)
                        n->minmtu = len;
+               if(n->mtuprobes > 30)
+                       n->mtuprobes = 30;
        }
 }
 
@@ -279,9 +314,6 @@ static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 
        inpkt->priority = 0;
 
-       if(n->connection)
-               n->connection->last_ping_time = now;
-
        if(!inpkt->data[12] && !inpkt->data[13])
                mtu_probe_h(n, inpkt, origlen);
        else
@@ -337,10 +369,13 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 
        if(n->options & OPTION_PMTU_DISCOVERY && inpkt->len > n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
                ifdebug(TRAFFIC) logger(LOG_INFO,
-                               "Packet for %s (%s) larger than minimum MTU, forwarding via TCP",
-                               n->name, n->hostname);
+                               "Packet for %s (%s) larger than minimum MTU, forwarding via %s",
+                               n->name, n->hostname, n != n->nexthop ? n->nexthop->name : "TCP");
 
-               send_tcppacket(n->nexthop->connection, origpkt);
+               if(n != n->nexthop)
+                       send_packet(n->nexthop, origpkt);
+               else
+                       send_tcppacket(n->nexthop->connection, origpkt);
 
                return;
        }
@@ -493,12 +528,16 @@ static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
        avl_node_t *node;
        edge_t *e;
        node_t *n = NULL;
+       static time_t last_hard_try = 0;
 
        for(node = edge_weight_tree->head; node; node = node->next) {
                e = node->data;
 
-               if(sockaddrcmp_noport(from, &e->address))
-                       continue;
+               if(sockaddrcmp_noport(from, &e->address)) {
+                       if(last_hard_try == now)
+                               continue;
+                       last_hard_try = now;
+               }
 
                if(!n)
                        n = e->to;