Only use broadcast at the start of the PMTU discovery phase.

[tinc] / src / net_packet.c

diff --git a/src/net_packet.c b/src/net_packet.c
index f2bcc3e..4b3496d 100644 (file)
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -61,13 +61,21 @@ static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999
 static void send_udppacket(node_t *, vpn_packet_t *);
 
 unsigned replaywin = 16;
+bool localdiscovery = false;
 
 #define MAX_SEQNO 1073741824
 
-// 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
+/* 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
+
+   Probes are sent in batches of three, with random sizes between the lower and
+   upper boundaries for the MTU thus far discovered.
+
+   In case local discovery is enabled, a fourth packet is added to each batch,
+   which will be broadcast to the local network.
+*/
 
 void send_mtu_probe(node_t *n) {
        vpn_packet_t packet;
@@ -118,7 +126,7 @@ void send_mtu_probe(node_t *n) {
                timeout = pingtimeout;
        }
 
-       for(i = 0; i < 3; i++) {
+       for(i = 0; i < 3 + localdiscovery; i++) {
                if(n->maxmtu <= n->minmtu)
                        len = n->maxmtu;
                else
@@ -130,7 +138,10 @@ void send_mtu_probe(node_t *n) {
                memset(packet.data, 0, 14);
                RAND_pseudo_bytes(packet.data + 14, len - 14);
                packet.len = len;
-               packet.priority = 0;
+               if(i >= 3 && n->mtuprobes <= 10)
+                       packet.priority = -1;
+               else
+                       packet.priority = 0;
 
                ifdebug(TRAFFIC) logger(LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
 
@@ -389,7 +400,6 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
        static int priority = 0;
 #endif
        int origpriority;
-       int sock;
 
        if(!n->status.reachable) {
                ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send UDP packet to unreachable node %s (%s)", n->name, n->hostname);
@@ -403,7 +413,7 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
                                   "No valid key known yet for %s (%s), forwarding via TCP",
                                   n->name, n->hostname);
 
-               if(n->last_req_key + 10 < now) {
+               if(n->last_req_key + 10 <= now) {
                        send_req_key(n);
                        n->last_req_key = now;
                }
@@ -476,26 +486,51 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 
        /* Determine which socket we have to use */
 
-       for(sock = 0; sock < listen_sockets; sock++)
-               if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
-                       break;
-
-       if(sock >= listen_sockets)
-               sock = 0;                               /* If none is available, just use the first and hope for the best. */
+       if(n->address.sa.sa_family != listen_socket[n->sock].sa.sa.sa_family) {
+               for(int sock = 0; sock < listen_sockets; sock++) {
+                       if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family) {
+                               n->sock = sock;
+                               break;
+                       }
+               }
+       }
 
        /* Send the packet */
 
+       struct sockaddr *sa;
+       socklen_t sl;
+       int sock;
+
+       /* Overloaded use of priority field: -1 means local broadcast */
+
+       if(origpriority == -1 && n->prevedge) {
+               struct sockaddr_in in;
+               in.sin_family = AF_INET;
+               in.sin_addr.s_addr = -1;
+               in.sin_port = n->prevedge->address.in.sin_port;
+               sa = (struct sockaddr *)&in;
+               sl = sizeof in;
+               sock = 0;
+       } else {
+               if(origpriority == -1)
+                       origpriority = 0;
+
+               sa = &(n->address.sa);
+               sl = SALEN(n->address.sa);
+               sock = n->sock;
+       }
+
 #if defined(SOL_IP) && defined(IP_TOS)
        if(priorityinheritance && origpriority != priority
-          && listen_socket[sock].sa.sa.sa_family == AF_INET) {
+          && listen_socket[n->sock].sa.sa.sa_family == AF_INET) {
                priority = origpriority;
                ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting outgoing packet priority to %d", priority);
-               if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
+               if(setsockopt(listen_socket[n->sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */
                        logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
        }
 #endif
 
-       if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa)) < 0 && !sockwouldblock(sockerrno)) {
+       if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, sa, sl) < 0 && !sockwouldblock(sockerrno)) {
                if(sockmsgsize(sockerrno)) {
                        if(n->maxmtu >= origlen)
                                n->maxmtu = origlen - 1;
@@ -518,7 +553,7 @@ void send_packet(const node_t *n, vpn_packet_t *packet) {
        if(n == myself) {
                if(overwrite_mac)
                         memcpy(packet->data, mymac.x, ETH_ALEN);
-               write_packet(packet);
+               devops.write(packet);
                return;
        }
 
@@ -599,6 +634,7 @@ static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
        if(hard)
                last_hard_try = now;
 
+       last_hard_try = now;
        return n;
 }
 
@@ -609,7 +645,7 @@ void handle_incoming_vpn_data(int sock) {
        socklen_t fromlen = sizeof(from);
        node_t *n;
 
-       pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
+       pkt.len = recvfrom(listen_socket[sock].udp, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 
        if(pkt.len < 0) {
                if(!sockwouldblock(sockerrno))
@@ -635,5 +671,7 @@ void handle_incoming_vpn_data(int sock) {
                        return;
        }
 
+       n->sock = sock;
+
        receive_udppacket(n, &pkt);
 }