+
+ /* Begin with mesh->self */
+
+ mesh->self->status.visited = mesh->threadstarted;
+ mesh->self->nexthop = mesh->self;
+ mesh->self->prevedge = NULL;
+ mesh->self->distance = 0;
+ list_insert_head(todo_list, mesh->self);
+
+ /* Loop while todo_list is filled */
+
+ for list_each(node_t, n, todo_list) { /* "n" is the node from which we start */
+ logger(mesh, MESHLINK_DEBUG, " Examining edges from %s", n->name);
+
+ if(n->distance < 0) {
+ abort();
+ }
+
+ for splay_each(edge_t, e, n->edge_tree) { /* "e" is the edge connected to "from" */
+ if(!e->reverse) {
+ continue;
+ }
+
+ /* Situation:
+
+ /
+ /
+ ----->(n)---e-->(e->to)
+ \
+ \
+
+ Where e is an edge, (n) and (e->to) are nodes.
+ n->address is set to the e->address of the edge left of n to n.
+ We are currently examining the edge e right of n from n:
+
+ - If edge e provides for better reachability of e->to, update
+ e->to and (re)add it to the todo_list to (re)examine the reachability
+ of nodes behind it.
+ */
+
+ if(e->to->status.visited
+ && (e->to->distance != n->distance + 1 || e->weight >= e->to->prevedge->weight)) {
+ continue;
+ }
+
+ e->to->status.visited = true;
+ e->to->nexthop = (n->nexthop == mesh->self) ? e->to : n->nexthop;
+ e->to->prevedge = e;
+ e->to->distance = n->distance + 1;
+
+ if(!e->to->status.reachable || (e->to->address.sa.sa_family == AF_UNSPEC && e->address.sa.sa_family != AF_UNKNOWN)) {
+ update_node_udp(mesh, e->to, &e->address);
+ }
+
+ list_insert_tail(todo_list, e->to);
+ }
+
+ next = node->next; /* Because the list_insert_tail() above could have added something extra for us! */
+ list_delete_node(todo_list, node);
+ }
+
+ list_free(todo_list);
+}
+
+static void check_reachability(meshlink_handle_t *mesh) {
+ /* Check reachability status. */
+
+ int reachable = -1; /* Don't count ourself */
+
+ for splay_each(node_t, n, mesh->nodes) {
+ if(n->status.visited) {
+ reachable++;
+ }
+
+ /* Check for nodes that have changed session_id */
+ if(n->status.visited && n->prevedge && n->prevedge->reverse->session_id != n->session_id) {
+ n->session_id = n->prevedge->reverse->session_id;
+
+ if(n->utcp) {
+ utcp_abort_all_connections(n->utcp);
+ }
+
+ if(n->status.visited == n->status.reachable) {
+ /* This session replaces the previous one without changing reachability status.
+ * We still need to reset the UDP SPTPS state.
+ */
+ n->status.validkey = false;
+ sptps_stop(&n->sptps);
+ n->status.waitingforkey = false;
+ n->last_req_key = 0;
+
+ n->status.udp_confirmed = false;
+ n->maxmtu = MTU;
+ n->minmtu = 0;
+ n->mtuprobes = 0;
+
+ timeout_del(&mesh->loop, &n->mtutimeout);
+ }
+ }
+
+ if(n->status.visited != n->status.reachable) {
+ n->status.reachable = !n->status.reachable;
+ n->status.dirty = true;
+
+ if(!n->status.blacklisted) {
+ if(n->status.reachable) {
+ logger(mesh, MESHLINK_DEBUG, "Node %s became reachable", n->name);
+ bool first_time_reachable = !n->last_reachable;
+ n->last_reachable = time(NULL);
+
+ if(first_time_reachable) {
+ if(!node_write_config(mesh, n)) {
+ logger(mesh, MESHLINK_WARNING, "Could not write host config file for node %s!\n", n->name);
+
+ }
+ }
+ } else {
+ logger(mesh, MESHLINK_DEBUG, "Node %s became unreachable", n->name);
+ n->last_unreachable = time(NULL);
+ }
+ }
+
+ /* TODO: only clear status.validkey if node is unreachable? */
+
+ n->status.validkey = false;
+ sptps_stop(&n->sptps);
+ n->status.waitingforkey = false;
+ n->last_req_key = 0;
+
+ n->status.udp_confirmed = false;
+ n->maxmtu = MTU;
+ n->minmtu = 0;
+ n->mtuprobes = 0;
+
+ timeout_del(&mesh->loop, &n->mtutimeout);
+
+ if(!n->status.blacklisted) {
+ update_node_status(mesh, n);
+ }
+
+ if(!n->status.reachable) {
+ update_node_udp(mesh, n, NULL);
+ n->status.broadcast = false;
+ } else if(n->connection) {
+ if(n->connection->status.initiator) {
+ send_req_key(mesh, n);
+ }
+ }
+
+ if(n->utcp) {
+ utcp_offline(n->utcp, !n->status.reachable);
+ }
+ }
+ }
+
+ if(mesh->reachable != reachable) {
+ if(!reachable) {
+ mesh->last_unreachable = mesh->loop.now.tv_sec;
+
+ if(mesh->threadstarted) {
+ timeout_set(&mesh->loop, &mesh->periodictimer, &(struct timespec) {
+ 0, prng(mesh, TIMER_FUDGE)
+ });
+ }
+ }
+
+ mesh->reachable = reachable;