Send one MTU probe at a time.

[tinc] / src / net_packet.c

diff --git a/src/net_packet.c b/src/net_packet.c
index 3078e54..9bebca4 100644 (file)
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -69,7 +69,7 @@ static void try_fix_mtu(node_t *n) {
        if(n->mtuprobes < 0)
                return;
 
-       if(n->mtuprobes == 30 || n->minmtu >= n->maxmtu) {
+       if(n->mtuprobes == 90 || n->minmtu >= n->maxmtu) {
                if(n->minmtu > n->maxmtu)
                        n->minmtu = n->maxmtu;
                else
@@ -144,7 +144,7 @@ static void udp_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
                if(probelen >= n->maxmtu + 8) {
                        logger(DEBUG_TRAFFIC, LOG_INFO, "Increase in PMTU to %s (%s) detected, restarting PMTU discovery", n->name, n->hostname);
                        n->maxmtu = MTU;
-                       n->mtuprobes = 10;
+                       n->mtuprobes = 30;
                        return;
                }
 
@@ -181,7 +181,7 @@ static void udp_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
                        n->rtt = diff.tv_sec + diff.tv_usec * 1e-6;
                        n->probe_time = probe_timestamp;
                } else if(n->probe_counter == 3) {
-                       /* TODO: this will never fire after initial MTU discovery. */
+                       /* TODO: this will never fire - we're not sending batches of three anymore. */
                        struct timeval probe_timestamp_diff;
                        timersub(&probe_timestamp, &n->probe_time, &probe_timestamp_diff);
                        n->bandwidth = 2.0 * probelen / (probe_timestamp_diff.tv_sec + probe_timestamp_diff.tv_usec * 1e-6);
@@ -903,8 +903,8 @@ static void try_mtu(node_t *n) {
                return;
        }
 
-       /* mtuprobes == 0..29: initial discovery, send bursts with 1 second interval, mtuprobes++
-          mtuprobes ==    30: fix MTU, and go to -1
+       /* mtuprobes == 0..89: initial discovery, send bursts with 1 second interval, mtuprobes++
+          mtuprobes ==    90: fix MTU, and go to -1
           mtuprobes ==    -1: send one >maxmtu probe every pingtimeout */
 
        struct timeval now;
@@ -912,7 +912,7 @@ static void try_mtu(node_t *n) {
        struct timeval elapsed;
        timersub(&now, &n->probe_sent_time, &elapsed);
        if(n->mtuprobes >= 0) {
-               if(n->mtuprobes != 0 && elapsed.tv_sec < 1)
+               if(n->mtuprobes != 0 && elapsed.tv_sec == 0 && elapsed.tv_usec < 333333)
                        return;
        } else {
                if(elapsed.tv_sec < pingtimeout)
@@ -928,15 +928,12 @@ static void try_mtu(node_t *n) {
                if(n->maxmtu + 8 < MTU)
                        send_udp_probe_packet(n, n->maxmtu + 8);
        } else {
-               /* Probes are sent in batches of three, with random sizes between the
+               /* Probes are sent with random sizes between the
                   lower and upper boundaries for the MTU thus far discovered. */
-               for (int i = 0; i < 3; i++) {
-                       int len = n->maxmtu;
-                       if(n->minmtu < n->maxmtu)
-                               len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
-
-                       send_udp_probe_packet(n, MAX(len, 64));
-               }
+               int len = n->maxmtu;
+               if(n->minmtu < n->maxmtu)
+                       len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
+               send_udp_probe_packet(n, MAX(len, 64));
 
                if(n->mtuprobes >= 0)
                        n->mtuprobes++;