send_udppacket(n, &packet);
}
-static void send_mtu_probe_handler(void *data) {
- node_t *n = data;
-
- if(!n->status.reachable || !n->status.validkey) {
- logger(DEBUG_TRAFFIC, LOG_INFO, "Trying to send MTU probe to unreachable or rekeying node %s (%s)", n->name, n->hostname);
- n->mtuprobes = 0;
+// This function tries to determines the MTU of a node.
+// By calling this function repeatedly, n->minmtu will be progressively increased, and at some point, n->mtu will be fixed to n->minmtu.
+// If the MTU is already fixed, this function checks if it can be increased.
+static void try_mtu(node_t *n) {
+ if(!(n->options & OPTION_PMTU_DISCOVERY))
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;
+ if(udp_discovery && !n->status.udp_confirmed) {
+ n->mtuprobes = 0;
n->minmtu = 0;
n->maxmtu = MTU;
+ return;
}
- 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 */
+
+ struct timeval now;
+ gettimeofday(&now, NULL);
+ struct timeval elapsed;
+ timersub(&now, &n->probe_sent_time, &elapsed);
+ if(n->mtuprobes < 31) {
+ if(n->mtuprobes != 0 && elapsed.tv_sec < 1)
+ return;
+ } else {
+ if(elapsed.tv_sec < pingtimeout)
+ return;
}
if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) {
n->mtuprobes = 31;
}
+ int timeout;
if(n->mtuprobes == 31) {
- timeout = pinginterval;
- goto end;
- } else if(n->mtuprobes == 32) {
- timeout = pingtimeout;
- }
-
- /* 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));
+ /* 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);
+ } 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);
+
+ send_udp_probe_packet(n, MAX(len, 64));
+ }
+ n->mtuprobes++;
}
n->probe_counter = 0;
- gettimeofday(&n->probe_time, NULL);
+ n->probe_sent_time = now;
+ n->probe_time = now;
/* 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)
n->prev_received_seqno = n->received_seqno;
n->prev_received = n->received;
-
-end:
- timeout_set(&n->mtutimeout, &(struct timeval){timeout, rand() % 100000});
-}
-
-void send_mtu_probe(node_t *n) {
- timeout_add(&n->mtutimeout, send_mtu_probe_handler, n, &(struct timeval){1, 0});
- send_mtu_probe_handler(n);
}
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;
}
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 */
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);
if(!n->status.sptps && !via->status.validkey && via->last_req_key + 10 <= now.tv_sec) {
send_req_key(via);
via->last_req_key = now.tv_sec;
- } else if(via == n || !n->status.sptps || (via->options >> 24) >= 4)
+ } else if(via == n || !n->status.sptps || (via->options >> 24) >= 4) {
try_udp(via);
+ try_mtu(via);
+ }
/* If we don't know how to reach "via" yet, then try to reach it through a relay. */
if(n->status.sptps && !via->status.udp_confirmed && via->nexthop != via && (via->nexthop->options >> 24) >= 4)
projects / tinc / blobdiff