unsigned replaywin = 16;
bool localdiscovery = true;
+bool udp_discovery = true;
+int udp_discovery_interval = 9;
+int udp_discovery_timeout = 30;
#define MAX_SEQNO 1073741824
-static void send_mtu_probe_packet(node_t *n, int len) {
+static void send_udp_probe_packet(node_t *n, int len) {
vpn_packet_t packet;
packet.offset = DEFAULT_PACKET_OFFSET;
memset(DATA(&packet), 0, 14);
packet.len = len;
packet.priority = 0;
- logger(DEBUG_TRAFFIC, LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
+ logger(DEBUG_TRAFFIC, LOG_INFO, "Sending UDP probe length %d to %s (%s)", len, n->name, n->hostname);
send_udppacket(n, &packet);
}
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)
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;
- }
-
- /* 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_mtu_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_mtu_probe_packet(n, MAX(len, 64));
- }
-
- /* In case local discovery is enabled, another packet is added to each batch,
- which will be broadcast to the local network. */
- if(localdiscovery && n->mtuprobes <= 10 && n->prevedge) {
- n->status.send_locally = true;
- send_mtu_probe_packet(n, 16);
- n->status.send_locally = false;
+ } 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));
+ }
+ timeout = 1;
+ n->mtuprobes++;
}
n->probe_counter = 0;
/* 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});
}
send_mtu_probe_handler(n);
}
-static void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
+static void udp_probe_timeout_handler(void *data) {
+ node_t *n = data;
+ if(!n->status.udp_confirmed)
+ return;
+
+ 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 = 0;
+ n->minmtu = 0;
+ n->maxmtu = MTU;
+}
+
+static void udp_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
if(!DATA(packet)[0]) {
- logger(DEBUG_TRAFFIC, LOG_INFO, "Got MTU probe request %d from %s (%s)", packet->len, n->name, n->hostname);
+ logger(DEBUG_TRAFFIC, LOG_INFO, "Got UDP probe request %d from %s (%s)", packet->len, n->name, n->hostname);
/* It's a probe request, send back a reply */
length_t probelen = len;
if (DATA(packet)[0] == 2) {
if (len < 3)
- logger(DEBUG_TRAFFIC, LOG_WARNING, "Received invalid (too short) MTU probe reply from %s (%s)", n->name, n->hostname);
+ logger(DEBUG_TRAFFIC, LOG_WARNING, "Received invalid (too short) UDP probe reply from %s (%s)", n->name, n->hostname);
else {
uint16_t probelen16; memcpy(&probelen16, DATA(packet) + 1, 2); probelen = ntohs(probelen16);
}
}
- logger(DEBUG_TRAFFIC, LOG_INFO, "Got type %d MTU probe reply %d from %s (%s)", DATA(packet)[0], probelen, n->name, n->hostname);
+ logger(DEBUG_TRAFFIC, LOG_INFO, "Got type %d UDP probe reply %d from %s (%s)", DATA(packet)[0], probelen, n->name, n->hostname);
/* It's a valid reply: now we know bidirectional communication
is possible using the address and socket that the reply
packet used. */
-
n->status.udp_confirmed = true;
- /* 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(udp_discovery) {
+ timeout_del(&n->udp_ping_timeout);
+ timeout_add(&n->udp_ping_timeout, &udp_probe_timeout_handler, n, &(struct timeval){udp_discovery_timeout, 0});
+ }
- 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);
inpkt->priority = 0;
if(!DATA(inpkt)[12] && !DATA(inpkt)[13])
- mtu_probe_h(n, inpkt, origlen);
+ udp_probe_h(n, inpkt, origlen);
else
receive_packet(n, inpkt);
return true;
if(type == PKT_PROBE) {
inpkt.len = len;
memcpy(DATA(&inpkt), data, len);
- mtu_probe_h(from, &inpkt, len);
+ udp_probe_h(from, &inpkt, len);
return true;
}
return;
}
+// This function tries to establish a UDP tunnel to a node so that packets can be sent.
+// If a tunnel is already established, it makes sure it stays up.
+// This function makes no guarantees - it is up to the caller to check the node's state to figure out if UDP is usable.
+static void try_udp(node_t* n) {
+ if(!udp_discovery)
+ return;
+
+ struct timeval now;
+ gettimeofday(&now, NULL);
+ struct timeval ping_tx_elapsed;
+ timersub(&now, &n->udp_ping_sent, &ping_tx_elapsed);
+
+ if(ping_tx_elapsed.tv_sec >= udp_discovery_interval) {
+ send_udp_probe_packet(n, MAX(n->minmtu, 16));
+ n->udp_ping_sent = now;
+
+ if(localdiscovery && !n->status.udp_confirmed && n->prevedge) {
+ n->status.send_locally = true;
+ send_udp_probe_packet(n, 16);
+ n->status.send_locally = false;
+ }
+ }
+}
+
// This function tries to establish a tunnel to a node (or its relay) so that packets can be sent (e.g. get SPTPS keys).
// If a tunnel is already established, it tries to improve it (e.g. by trying to establish a UDP tunnel instead of TCP).
// This function makes no guarantees - it is up to the caller to check the node's state to figure out if TCP and/or UDP is usable.
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)
+ try_udp(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