Use addresses learned from other nodes when making outgoing connections.

Before, when making a meta-connection to a node (either because of a ConnectTo
or because AutoConnect is set), tinc required one or more Address statements
in the corresponding host config file. However, tinc learns addresses from
other nodes that it uses for UDP connections. We can use those just as well for
TCP connections.

diff --git a/src/net_socket.c b/src/net_socket.c
index 30b36a7..a41b887 100644 (file)
--- a/src/net_socket.c
+++ b/src/net_socket.c
@@ -547,6 +547,39 @@ begin:
        return true;
 }
 
+// Find edges pointing to this node, and use them to build a list of unique, known addresses.
+static struct addrinfo *get_known_addresses(node_t *n) {
+       struct addrinfo *ai = NULL;
+
+       for splay_each(edge_t, e, n->edge_tree) {
+               if(!e->reverse)
+                       continue;
+
+               bool found = false;
+               for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
+                       if(!sockaddrcmp(&e->reverse->address, (sockaddr_t *)aip->ai_addr)) {
+                               found = true;
+                               break;
+                       }
+               }
+               if(found)
+                       continue;
+
+               struct addrinfo *nai = xzalloc(sizeof *nai);
+               if(ai)
+                       ai->ai_next = nai;
+               ai = nai;
+               ai->ai_family = e->reverse->address.sa.sa_family;
+               ai->ai_socktype = SOCK_STREAM;
+               ai->ai_protocol = IPPROTO_TCP;
+               ai->ai_addrlen = SALEN(e->reverse->address.sa);
+               ai->ai_addr = xmalloc(ai->ai_addrlen);
+               memcpy(ai->ai_addr, &e->reverse->address, ai->ai_addrlen);
+       }
+
+       return ai;
+}
+
 void setup_outgoing_connection(outgoing_t *outgoing) {
        timeout_del(&outgoing->ev);
 
@@ -564,8 +597,12 @@ void setup_outgoing_connection(outgoing_t *outgoing) {
        outgoing->cfg = lookup_config(outgoing->config_tree, "Address");
 
        if(!outgoing->cfg) {
-               logger(DEBUG_ALWAYS, LOG_ERR, "No address specified for %s", outgoing->name);
-               return;
+               if(n)
+                       outgoing->aip = outgoing->ai = get_known_addresses(n);
+               if(!outgoing->ai) {
+                       logger(DEBUG_ALWAYS, LOG_ERR, "No address known for %s", outgoing->name);
+                       return;
+               }
        }
 
        do_outgoing_connection(outgoing);