Fix a possible crash when sending the HUP signal.

When the HUP signal is sent while some outgoing connections have not been made
yet, or are being retried, a NULL pointer could be dereferenced resulting in
tinc crashing. We fix this by more careful handling of outgoing_ts, and by
deleting all connections that have not been fully activated yet at the HUP
signal is received.

src/net.c

@@ -431,7 +431,7 @@ int main_loop(void) {
 
 		if(sighup) {
 			connection_t *c;
-			avl_node_t *node;
+			avl_node_t *node, *next;
 			char *fname;
 			struct stat s;
 			
@@ -447,6 +447,31 @@ int main_loop(void) {
 				return 1;
 			}
 
+			/* Cancel non-active outgoing connections */
+
+			for(node = connection_tree->head; node; node = next) {
+				next = node->next;
+				c = node->data;
+
+				c->outgoing = NULL;
+
+				if(c->status.connecting) {
+					terminate_connection(c, false);
+					connection_del(c);
+				}
+			}
+
+			/* Wipe list of outgoing connections */
+
+			for(list_node_t *node = outgoing_list->head; node; node = node->next) {
+				outgoing_t *outgoing = node->data;
+
+				if(outgoing->event)
+					event_del(outgoing->event);
+			}
+
+			list_delete_list(outgoing_list);
+
 			/* Close connections to hosts that have a changed or deleted host config file */
 			
 			for(node = connection_tree->head; node; node = node->next) {