Move UDP probe reply code into its own function.

This reduces the level of indentation, and prepares for sending gratuitous type 2 probe replies.

diff --git a/src/net_packet.c b/src/net_packet.c
index 96f8f10..52c46e1 100644 (file)
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -101,75 +101,79 @@ static void udp_probe_timeout_handler(void *data) {
        n->maxmtu = MTU;
 }
 
-static void udp_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
-       if(!DATA(packet)[0]) {
-               /* It's a probe request, send back a reply */
+static void send_udp_probe_reply(node_t *n, vpn_packet_t *packet, length_t len) {
+       if(!n->status.sptps && !n->status.validkey) {
+               // But not if we don't have his key.
+               logger(DEBUG_TRAFFIC, LOG_INFO, "Got UDP probe request from %s (%s) but we don't have his key yet", n->name, n->hostname);
+               return;
+       }
 
-               if(!n->status.sptps && !n->status.validkey) {
-                       // But not if we don't have his key.
-                       logger(DEBUG_TRAFFIC, LOG_INFO, "Got UDP probe request from %s (%s) but we don't have his key yet", n->name, n->hostname);
-                       return;
-               }
+       logger(DEBUG_TRAFFIC, LOG_INFO, "Got UDP 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);
+       /* Type 2 probe replies were introduced in protocol 17.3 */
+       if ((n->options >> 24) >= 3) {
+               uint8_t *data = DATA(packet);
+               *data++ = 2;
+               uint16_t len16 = htons(len);
+               memcpy(data, &len16, 2);
+               packet->len = MIN_PROBE_SIZE;
+       } else {
+               /* Legacy protocol: n won't understand type 2 probe replies. */
+               DATA(packet)[0] = 1;
+       }
 
-               /* Type 2 probe replies were introduced in protocol 17.3 */
-               if ((n->options >> 24) >= 3) {
-                       uint8_t *data = DATA(packet);
-                       *data++ = 2;
-                       uint16_t len16 = htons(len); memcpy(data, &len16, 2); data += 2;
-                       packet->len = MIN_PROBE_SIZE;
-               } else {
-                       /* Legacy protocol: n won't understand type 2 probe replies. */
-                       DATA(packet)[0] = 1;
-               }
+       /* Temporarily set udp_confirmed, so that the reply is sent
+          back exactly the way it came in. */
 
-               /* Temporarily set udp_confirmed, so that the reply is sent
-                  back exactly the way it came in. */
+       bool udp_confirmed = n->status.udp_confirmed;
+       n->status.udp_confirmed = true;
+       send_udppacket(n, packet);
+       n->status.udp_confirmed = udp_confirmed;
+}
 
-               bool udp_confirmed = n->status.udp_confirmed;
-               n->status.udp_confirmed = true;
-               send_udppacket(n, packet);
-               n->status.udp_confirmed = udp_confirmed;
-       } else {
-               length_t probelen = len;
-               if (DATA(packet)[0] == 2) {
-                       if (len < 3)
-                               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 UDP probe reply %d from %s (%s)", DATA(packet)[0], probelen, n->name, n->hostname);
+static void udp_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
+       if(!DATA(packet)[0]) {
+               /* It's a probe request, send back a reply */
+               return send_udp_probe_reply(n, packet, len);
+       }
+
+       if (DATA(packet)[0] == 2) {
+               // It's a type 2 probe reply, use the length field inside the packet
+               uint16_t len16;
+               memcpy(&len16, DATA(packet) + 1, 2);
+               len = ntohs(len16);
+       }
 
-               /* 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;
+       logger(DEBUG_TRAFFIC, LOG_INFO, "Got type %d UDP probe reply %d from %s (%s)", DATA(packet)[0], len, n->name, n->hostname);
 
-               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});
-               }
+       /* 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(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(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(len > n->maxmtu) {
+               logger(DEBUG_TRAFFIC, LOG_INFO, "Increase in PMTU to %s (%s) detected, restarting PMTU discovery", n->name, n->hostname);
+               n->minmtu = len;
+               n->maxmtu = MTU;
+               /* Set mtuprobes to 1 so that try_mtu() doesn't reset maxmtu */
+               n->mtuprobes = 1;
+               return;
+       } else if(n->mtuprobes < 0 && len == n->maxmtu) {
+               /* We got a maxmtu sized packet, confirming the PMTU is still valid. */
+               n->mtuprobes = -1;
+               n->mtu_ping_sent = now;
+       }
 
-               /* If applicable, raise the minimum supported MTU */
+       /* If applicable, raise the minimum supported MTU */
 
-               if(n->minmtu < probelen) {
-                       n->minmtu = probelen;
-                       try_fix_mtu(n);
-               }
+       if(n->minmtu < len) {
+               n->minmtu = len;
+               try_fix_mtu(n);
        }
 }