projects / tinc / blobdiff
? search:
summary | shortlog | log | commit | commitdiff | tree
raw | inline | side by side
Introduce lightweight PMTU probe replies.
[tinc] / src / net_packet.c
diff --git a/src/net_packet.c b/src/net_packet.c
index c255261..d700fd6 100644 (file)
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -56,6 +56,7 @@ static void send_udppacket(node_t *, vpn_packet_t *);
 
 unsigned replaywin = 16;
 bool localdiscovery = false;
+sockaddr_t localdiscovery_address;
 
 #define MAX_SEQNO 1073741824
 
@@ -178,12 +179,20 @@ void send_mtu_probe(node_t *n) {
 }
 
 static void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
-       logger(DEBUG_TRAFFIC, LOG_INFO, "Got MTU probe length %d from %s (%s)", packet->len, n->name, n->hostname);
-
        if(!packet->data[0]) {
+               logger(DEBUG_TRAFFIC, LOG_INFO, "Got MTU probe request %d from %s (%s)", packet->len, n->name, n->hostname);
+
                /* It's a probe request, send back a reply */
 
-               packet->data[0] = 1;
+               /* Type 2 probe replies were introduced in protocol 17.3 */
+               if ((n->options >> 24) == 3) {
+                       uint8_t* data = packet->data;
+                       *data++ = 2;
+                       uint16_t len16 = htons(len); memcpy(data, &len16, 2); data += 2;
+               } else {
+                       /* Legacy protocol: n won't understand type 2 probe replies. */
+                       packet->data[0] = 1;
+               }
 
                /* Temporarily set udp_confirmed, so that the reply is sent
                   back exactly the way it came in. */
@@ -193,6 +202,16 @@ static void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
                send_udppacket(n, packet);
                n->status.udp_confirmed = udp_confirmed;
        } else {
+               length_t probelen = len;
+               if (packet->data[0] == 2) {
+                       if (len < 3)
+                               logger(DEBUG_TRAFFIC, LOG_WARNING, "Received invalid (too short) MTU probe reply from %s (%s)", n->name, n->hostname);
+                       else {
+                               uint16_t probelen16; memcpy(&probelen16, packet->data + 1, 2); probelen = ntohs(probelen16);
+                       }
+               }
+               logger(DEBUG_TRAFFIC, LOG_INFO, "Got type %d MTU probe reply %d from %s (%s)", packet->data[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. */
@@ -202,7 +221,7 @@ static void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
                /* If we haven't established the PMTU yet, restart the discovery process. */
 
                if(n->mtuprobes > 30) {
-                       if (len == n->maxmtu + 8) {
+                       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;
@@ -217,10 +236,10 @@ static void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 
                /* If applicable, raise the minimum supported MTU */
 
-               if(len > n->maxmtu)
-                       len = n->maxmtu;
-               if(n->minmtu < len)
-                       n->minmtu = len;
+               if(probelen > n->maxmtu)
+                       probelen = n->maxmtu;
+               if(n->minmtu < probelen)
+                       n->minmtu = probelen;
 
                /* Calculate RTT and bandwidth.
                   The RTT is the time between the MTU probe burst was sent and the first
@@ -237,7 +256,7 @@ static void mtu_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 = now;
                } else if(n->probe_counter == 3) {
-                       n->bandwidth = 2.0 * len / (diff.tv_sec + diff.tv_usec * 1e-6);
+                       n->bandwidth = 2.0 * probelen / (diff.tv_sec + diff.tv_usec * 1e-6);
                        logger(DEBUG_TRAFFIC, LOG_DEBUG, "%s (%s) RTT %.2f ms, burst bandwidth %.3f Mbit/s, rx packet loss %.2f %%", n->name, n->hostname, n->rtt * 1e3, n->bandwidth * 8e-6, n->packetloss * 1e2);
                }
        }
@@ -332,13 +351,21 @@ static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
        size_t outlen;
 
        if(n->status.sptps) {
+               if(!n->sptps.state) {
+                       if(!n->status.waitingforkey) {
+                               logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got packet from %s (%s) but we haven't exchanged keys yet", n->name, n->hostname);
+                               send_req_key(n);
+                       } else {
+                               logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet", n->name, n->hostname);
+                       }
+                       return;
+               }
                sptps_receive_data(&n->sptps, (char *)&inpkt->seqno, inpkt->len);
                return;
        }
 
        if(!cipher_active(n->incipher)) {
-               logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet",
-                                       n->name, n->hostname);
+               logger(DEBUG_TRAFFIC, LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet", n->name, n->hostname);
                return;
        }
 
@@ -572,12 +599,22 @@ static void choose_broadcast_address(const node_t *n, const sockaddr_t **sa, int
        *sock = rand() % listen_sockets;
 
        if(listen_socket[*sock].sa.sa.sa_family == AF_INET6) {
-               broadcast_ipv6.in6.sin6_port = n->prevedge->address.in.sin_port;
-               broadcast_ipv6.in6.sin6_scope_id = listen_socket[*sock].sa.in6.sin6_scope_id;
-               *sa = &broadcast_ipv6;
+               if(localdiscovery_address.sa.sa_family == AF_INET6) {
+                       localdiscovery_address.in6.sin6_port = n->prevedge->address.in.sin_port;
+                       *sa = &localdiscovery_address;
+               } else {
+                       broadcast_ipv6.in6.sin6_port = n->prevedge->address.in.sin_port;
+                       broadcast_ipv6.in6.sin6_scope_id = listen_socket[*sock].sa.in6.sin6_scope_id;
+                       *sa = &broadcast_ipv6;
+               }
        } else {
-               broadcast_ipv4.in.sin_port = n->prevedge->address.in.sin_port;
-               *sa = &broadcast_ipv4;
+               if(localdiscovery_address.sa.sa_family == AF_INET) {
+                       localdiscovery_address.in.sin_port = n->prevedge->address.in.sin_port;
+                       *sa = &localdiscovery_address;
+               } else {
+                       broadcast_ipv4.in.sin_port = n->prevedge->address.in.sin_port;
+                       *sa = &broadcast_ipv4;
+               }
        }
 }
 
@@ -669,7 +706,11 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
        /* Add the message authentication code */
 
        if(digest_active(n->outdigest)) {
-               digest_create(n->outdigest, &inpkt->seqno, inpkt->len, (char *)&inpkt->seqno + inpkt->len);
+               if(!digest_create(n->outdigest, &inpkt->seqno, inpkt->len, (char *)&inpkt->seqno + inpkt->len)) {
+                       logger(DEBUG_TRAFFIC, LOG_ERR, "Error while encrypting packet to %s (%s)", n->name, n->hostname);
+                       goto end;
+               }
+
                inpkt->len += digest_length(n->outdigest);
        }
 
tinc, the VPN daemon