+ Running time: O(EN)
+ Please note that sorting on weight is already done by add_edge().
+*/
+
+static void mst_kruskal(void) {
+ avl_node_t *node, *next;
+ edge_t *e;
+ node_t *n;
+ connection_t *c;
+ int nodes = 0;
+ int safe_edges = 0;
+ bool skipped;
+
+ /* Clear MST status on connections */
+
+ for(node = connection_tree->head; node; node = node->next) {
+ c = node->data;
+ c->status.mst = false;
+ }
+
+ /* Do we have something to do at all? */
+
+ if(!edge_weight_tree->head)
+ return;
+
+ ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Running Kruskal's algorithm:");
+
+ /* Clear visited status on nodes */
+
+ for(node = node_tree->head; node; node = node->next) {
+ n = node->data;
+ n->status.visited = false;
+ nodes++;
+ }
+
+ /* Starting point */
+
+ for(node = edge_weight_tree->head; node; node = node->next) {
+ e = node->data;
+ if(e->from->status.reachable) {
+ e->from->status.visited = true;
+ break;
+ }
+ }
+
+ /* Add safe edges */
+
+ for(skipped = false, node = edge_weight_tree->head; node; node = next) {
+ next = node->next;
+ e = node->data;
+
+ if(!e->reverse || e->from->status.visited == e->to->status.visited) {
+ skipped = true;
+ continue;
+ }
+
+ e->from->status.visited = true;
+ e->to->status.visited = true;
+
+ if(e->connection)
+ e->connection->status.mst = true;
+
+ if(e->reverse->connection)
+ e->reverse->connection->status.mst = true;
+
+ safe_edges++;
+
+ ifdebug(SCARY_THINGS) logger(LOG_DEBUG, " Adding edge %s - %s weight %d", e->from->name,
+ e->to->name, e->weight);
+
+ if(skipped) {
+ skipped = false;
+ next = edge_weight_tree->head;
+ continue;
+ }
+ }
+
+ ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Done, counted %d nodes and %d safe edges.", nodes,
+ safe_edges);
+}
+
+/* Implementation of a simple breadth-first search algorithm.
+ Running time: O(E)
+*/
+
+static void sssp_bfs(void) {
+ avl_node_t *node, *next, *to;
+ edge_t *e;
+ node_t *n;
+ list_t *todo_list;
+ list_node_t *from, *todonext;
+ bool indirect;
+ char *name;
+ char *address, *port;
+ char *envp[8] = {NULL};
+ int i;
+
+ todo_list = list_alloc(NULL);
+
+ /* Clear visited status on nodes */
+
+ for(node = node_tree->head; node; node = node->next) {
+ n = node->data;
+ n->status.visited = false;
+ n->status.indirect = true;
+ }
+
+ /* Begin with myself */
+
+ myself->status.visited = true;
+ myself->status.indirect = false;
+ myself->nexthop = myself;
+ myself->prevedge = NULL;
+ myself->via = myself;
+ list_insert_head(todo_list, myself);
+
+ /* Loop while todo_list is filled */
+
+ for(from = todo_list->head; from; from = todonext) { /* "from" is the node from which we start */
+ n = from->data;
+
+ for(to = n->edge_tree->head; to; to = to->next) { /* "to" is the edge connected to "from" */
+ e = to->data;
+
+ 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.
+ */
+
+ indirect = n->status.indirect || e->options & OPTION_INDIRECT;
+
+ if(e->to->status.visited
+ && (!e->to->status.indirect || indirect))
+ continue;
+
+ e->to->status.visited = true;
+ e->to->status.indirect = indirect;
+ e->to->nexthop = (n->nexthop == myself) ? e->to : n->nexthop;
+ e->to->prevedge = e;
+ e->to->via = indirect ? n->via : e->to;
+ e->to->options = e->options;
+
+ if(e->to->address.sa.sa_family == AF_UNSPEC && e->address.sa.sa_family != AF_UNKNOWN)
+ update_node_udp(e->to, &e->address);
+
+ list_insert_tail(todo_list, e->to);
+ }
+
+ todonext = from->next;
+ list_delete_node(todo_list, from);
+ }
+
+ list_free(todo_list);
+
+ /* Check reachability status. */
+
+ for(node = node_tree->head; node; node = next) {
+ next = node->next;
+ n = node->data;
+
+ if(n->status.visited != n->status.reachable) {
+ n->status.reachable = !n->status.reachable;
+
+ if(n->status.reachable) {
+ ifdebug(TRAFFIC) logger(LOG_DEBUG, "Node %s (%s) became reachable",
+ n->name, n->hostname);
+ } else {
+ ifdebug(TRAFFIC) logger(LOG_DEBUG, "Node %s (%s) became unreachable",
+ n->name, n->hostname);
+ }
+
+ /* TODO: only clear status.validkey if node is unreachable? */
+
+ n->status.validkey = false;
+ n->last_req_key = 0;
+
+ n->maxmtu = MTU;
+ n->minmtu = 0;
+ n->mtuprobes = 0;
+
+ if(n->mtuevent) {
+ event_del(n->mtuevent);
+ n->mtuevent = NULL;
+ }
+
+ xasprintf(&envp[0], "NETNAME=%s", netname ? : "");
+ xasprintf(&envp[1], "DEVICE=%s", device ? : "");
+ xasprintf(&envp[2], "INTERFACE=%s", iface ? : "");
+ xasprintf(&envp[3], "NODE=%s", n->name);
+ sockaddr2str(&n->address, &address, &port);
+ xasprintf(&envp[4], "REMOTEADDRESS=%s", address);
+ xasprintf(&envp[5], "REMOTEPORT=%s", port);
+ xasprintf(&envp[6], "NAME=%s", myself->name);
+
+ execute_script(n->status.reachable ? "host-up" : "host-down", envp);
+
+ xasprintf(&name,
+ n->status.reachable ? "hosts/%s-up" : "hosts/%s-down",
+ n->name);
+ execute_script(name, envp);
+
+ free(name);
+ free(address);
+ free(port);
+
+ for(i = 0; i < 7; i++)
+ free(envp[i]);
+
+ subnet_update(n, NULL, n->status.reachable);
+
+ if(!n->status.reachable) {
+ update_node_udp(n, NULL);
+ memset(&n->status, 0, sizeof n->status);
+ n->options = 0;
+ } else if(n->connection) {
+ send_ans_key(n);
+ }
+ }
+ }
+}
+
+void graph(void) {
+ subnet_cache_flush();
+ sssp_bfs();
+ mst_kruskal();
+ graph_changed = true;
+}
+
+
+
+/* Dump nodes and edges to a graphviz file.
+
+ The file can be converted to an image with
+ dot -Tpng graph_filename -o image_filename.png -Gconcentrate=true