diff --git a/src/net_packet.c b/src/net_packet.c index 7833fd87..f717dd78 100644 --- a/src/net_packet.c +++ b/src/net_packet.c @@ -87,32 +87,9 @@ static void send_mtu_probe_handler(void *data) { return; } - /* 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 */ - - n->mtuprobes++; - int timeout = 1; - - if(n->mtuprobes > 32) { - if(!n->minmtu) { - n->mtuprobes = 31; - timeout = pinginterval; - goto end; - } - - logger(DEBUG_TRAFFIC, LOG_INFO, "%s (%s) did not respond to UDP ping, restarting PMTU discovery", n->name, n->hostname); - n->status.udp_confirmed = false; - n->mtuprobes = 1; - n->minmtu = 0; - n->maxmtu = MTU; - } - - if(n->mtuprobes >= 10 && n->mtuprobes < 32 && !n->minmtu) { - logger(DEBUG_TRAFFIC, LOG_INFO, "No response to MTU probes from %s (%s)", n->name, n->hostname); - n->mtuprobes = 31; - } + /* mtuprobes == 0..29: initial discovery, send bursts with 1 second interval, mtuprobes++ + mtuprobes == 30: fix MTU, and go to 31 + mtuprobes == 31: send one >maxmtu probe every pingtimeout */ if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) { if(n->minmtu > n->maxmtu) @@ -124,26 +101,25 @@ static void send_mtu_probe_handler(void *data) { n->mtuprobes = 31; } + int timeout; if(n->mtuprobes == 31) { - timeout = pinginterval; - goto end; - } else if(n->mtuprobes == 32) { + /* After the initial discovery, we only send one >maxmtu probe + to detect PMTU increases. */ + if(n->maxmtu + 8 < MTU) + send_udp_probe_packet(n, n->maxmtu + 8); timeout = pingtimeout; - } + } else { + /* Probes are sent in batches of three, 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); - /* After the initial discovery, a fourth packet is added to each batch with a - size larger than the currently known PMTU, to test if the PMTU has increased. */ - if (n->mtuprobes >= 30 && n->maxmtu + 8 < MTU) - send_udp_probe_packet(n, n->maxmtu + 8); - - /* Probes are sent in batches of three, 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)); + send_udp_probe_packet(n, MAX(len, 64)); + } + timeout = 1; + n->mtuprobes++; } n->probe_counter = 0; @@ -151,6 +127,7 @@ static void send_mtu_probe_handler(void *data) { /* Calculate the packet loss of incoming traffic by comparing the rate of packets received to the rate with which the sequence number has increased. + TODO: this is unrelated to PMTU discovery - it should be moved elsewhere. */ if(n->received > n->prev_received) @@ -161,7 +138,6 @@ static void send_mtu_probe_handler(void *data) { n->prev_received_seqno = n->received_seqno; n->prev_received = n->received; -end: timeout_set(&n->mtutimeout, &(struct timeval){timeout, rand() % 100000}); } @@ -177,7 +153,7 @@ static void udp_probe_timeout_handler(void *data) { logger(DEBUG_TRAFFIC, LOG_INFO, "Too much time has elapsed since last UDP ping response from %s (%s), stopping UDP communication", n->name, n->hostname); n->status.udp_confirmed = false; - n->mtuprobes = 1; + n->mtuprobes = 0; n->minmtu = 0; n->maxmtu = MTU; } @@ -231,20 +207,11 @@ 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 we haven't established the PMTU yet, restart the discovery process. */ - - if(n->mtuprobes > 30) { - 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; - return; - } - - if(n->minmtu) - n->mtuprobes = 30; - else - n->mtuprobes = 1; + 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; + return; } /* If applicable, raise the minimum supported MTU */ @@ -278,6 +245,7 @@ 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. */ 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);