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Move detection of PMTU decrease to try_mtu().

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When we have fixed the PMTU, n->mtuprobes == -1. When we send MTU probes
when mtuprobes == -1, decrease mtuprobes, and reset it back to -1 in
mtu_probe_h(). If mtuprobes < -1, send MTU probes every second, until
mtuprobes <= -4, in which case we will restart MTU discovery.
This commit is contained in:
Guus Sliepen 2015-01-11 15:38:56 +01:00
parent e97e9b22cb
commit d639415937
1 changed files with 24 additions and 7 deletions
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31
src/net_packet.c
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@ -151,18 +151,20 @@ static void udp_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
timeout_add(&n->udp_ping_timeout, &udp_probe_timeout_handler, n, &(struct timeval){udp_discovery_timeout, 0});
}
if(probelen >= n->maxmtu + 1) {
if(probelen > n->maxmtu) {
logger(DEBUG_TRAFFIC, LOG_INFO, "Increase in PMTU to %s (%s) detected, restarting PMTU discovery", n->name, n->hostname);
n->minmtu = probelen;
n->maxmtu = MTU;
/* Set mtuprobes to 1 so that try_mtu() doesn't reset maxmtu */
n->mtuprobes = 1;
return;
} else if(n->mtuprobes < 0 && probelen == n->maxmtu) {
/* We got a maxmtu sized packet, confirming the PMTU is still valid. */
n->mtuprobes = -1;
}
/* If applicable, raise the minimum supported MTU */
if(probelen > n->maxmtu)
probelen = n->maxmtu;
if(n->minmtu < probelen) {
n->minmtu = probelen;
try_fix_mtu(n);
@ -968,7 +970,9 @@ static void try_mtu(node_t *n) {
/* mtuprobes == 0..19: initial discovery, send bursts with 1 second interval, mtuprobes++
mtuprobes == 20: fix MTU, and go to -1
mtuprobes == -1: send one >maxmtu probe every pinginterval */
mtuprobes == -1: send one maxmtu and one maxmtu+1 probe every pinginterval
mtuprobes ==-2..-3: send one maxmtu probe every second
mtuprobes == -4: maxmtu no longer valid, reset minmtu and maxmtu and go to 0 */
struct timeval elapsed;
timersub(&now, &n->mtu_ping_sent, &elapsed);
@ -976,20 +980,33 @@ static void try_mtu(node_t *n) {
if(n->mtuprobes != 0 && elapsed.tv_sec == 0 && elapsed.tv_usec < 333333)
return;
} else {
if(elapsed.tv_sec < pinginterval)
return;
if(n->mtuprobes < -1) {
if(elapsed.tv_sec < 1)
return;
} else {
if(elapsed.tv_sec < pinginterval)
return;
}
}
n->mtu_ping_sent = now;
try_fix_mtu(n);
if(n->mtuprobes < -3) {
/* We lost three MTU probes, restart discovery */
logger(DEBUG_TRAFFIC, LOG_INFO, "Decrease in PMTU to %s (%s) detected, restarting PMTU discovery", n->name, n->hostname);
n->mtuprobes = 0;
n->minmtu = 0;
}
if(n->mtuprobes < 0) {
/* After the initial discovery, we only send one maxmtu and one
maxmtu+1 probe to detect PMTU increases. */
send_udp_probe_packet(n, n->maxmtu);
if(n->maxmtu + 1 < MTU)
if(n->mtuprobes == -1 && n->maxmtu + 1 < MTU)
send_udp_probe_packet(n, n->maxmtu + 1);
n->mtuprobes--;
} else {
/* Before initial discovery begins, set maxmtu to the most likely value.
If it's underestimated, we will correct it after initial discovery. */