Use Dijkstra's algorithm. Based on patches from Max Rijevskiy.

diff --git a/src/graph.c b/src/graph.c
index e6d70af..02e8494 100644 (file)
--- a/src/graph.c
+++ b/src/graph.c
@@ -59,7 +59,7 @@
 #include "utils.h"
 
 /* Implementation of Kruskal's algorithm.
-   Running time: O(EN)
+   Running time: O(E)
    Please note that sorting on weight is already done by add_edge().
 */
 
@@ -68,9 +68,6 @@ void mst_kruskal(void) {
        edge_t *e;
        node_t *n;
        connection_t *c;
-       int nodes = 0;
-       int safe_edges = 0;
-       bool skipped;
 
        cp();
        
@@ -81,11 +78,6 @@ void mst_kruskal(void) {
                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 */
@@ -93,29 +85,16 @@ void mst_kruskal(void) {
        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) {
+       for(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;
+               if(!e->reverse || (e->from->status.visited && e->to->status.visited))
                        continue;
-               }
 
                e->from->status.visited = true;
                e->to->status.visited = true;
@@ -126,20 +105,135 @@ void mst_kruskal(void) {
                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;
+/* Implementation of Dijkstra's algorithm.
+   Running time: O(N^2)
+*/
+
+void sssp_dijkstra(void) {
+       splay_node_t *node, *to;
+       edge_t *e;
+       node_t *n, *m;
+       list_t *todo_list;
+       list_node_t *lnode, *nnode;
+       bool indirect;
+
+       cp();
+
+       todo_list = list_alloc(NULL);
+
+       ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Running Dijkstra's algorithm:");
+
+       /* 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;
+               n->distance = -1;
+       }
+
+       /* Begin with myself */
+
+       myself->status.indirect = false;
+       myself->nexthop = myself;
+       myself->via = myself;
+       myself->distance = 0;
+       list_insert_head(todo_list, myself);
+
+       /* Loop while todo_list is filled */
+
+       while(todo_list->head) {
+               n = NULL;
+               nnode = NULL;
+
+               /* Select node from todo_list with smallest distance */
+
+               for(lnode = todo_list->head; lnode; lnode = lnode->next) {
+                       m = lnode->data;
+                       if(!n || m->status.indirect < n->status.indirect || m->distance < n->distance) {
+                               n = m;
+                               nnode = lnode;
+                       }
+               }
+
+               /* Mark this node as visited and remove it from the todo_list */
+
+               n->status.visited = true;
+               list_unlink_node(todo_list, nnode);
+
+               /* Update distance of neighbours and add them to the todo_list */
+
+               for(to = n->edge_tree->head; to; to = to->next) {       /* "to" is the edge connected to "from" */
+                       e = to->data;
+
+                       if(e->to->status.visited || !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 e->reverse->address != n->address, then e->to is probably
+                            not reachable for the nodes left of n. We do as if the indirectdata
+                            flag is set on edge e.
+                          - If edge e provides for better reachability of e->to, update e->to.
+                        */
+
+                       if(e->to->distance < 0)
+                               list_insert_tail(todo_list, e->to);
+
+                       indirect = n->status.indirect || e->options & OPTION_INDIRECT || ((n != myself) && sockaddrcmp(&n->address, &e->reverse->address));
+
+                       if(e->to->distance >= 0 && (!e->to->status.indirect || indirect) && e->to->distance <= n->distance + e->weight)
+                               continue;
+
+                       e->to->distance = n->distance + e->weight;
+                       e->to->status.indirect = indirect;
+                       e->to->nexthop = (n->nexthop == myself) ? e->to : n->nexthop;
+                       e->to->via = indirect ? n->via : e->to;
+                       e->to->options = e->options;
+
+                       if(sockaddrcmp(&e->to->address, &e->address)) {
+                               node = splay_unlink(node_udp_tree, e->to);
+                               sockaddrfree(&e->to->address);
+                               sockaddrcpy(&e->to->address, &e->address);
+
+                               if(e->to->hostname)
+                                       free(e->to->hostname);
+
+                               e->to->hostname = sockaddr2hostname(&e->to->address);
+
+                               if(node)
+                                       splay_insert_node(node_udp_tree, node);
+
+                               if(e->to->options & OPTION_PMTU_DISCOVERY) {
+                                       e->to->mtuprobes = 0;
+                                       e->to->minmtu = 0;
+                                       e->to->maxmtu = MTU;
+                                       if(e->to->status.validkey)
+                                               send_mtu_probe(e->to);
+                               }
+                       }
+
+                       ifdebug(SCARY_THINGS) logger(LOG_DEBUG, " Updating edge %s - %s weight %d distance %d", e->from->name,
+                                          e->to->name, e->weight, e->to->distance);
                }
        }
 
-       ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Done, counted %d nodes and %d safe edges.", nodes,
-                          safe_edges);
+       list_free(todo_list);
 }
 
 /* Implementation of a simple breadth-first search algorithm.
@@ -147,16 +241,12 @@ void mst_kruskal(void) {
 */
 
 void sssp_bfs(void) {
-       splay_node_t *node, *next, *to;
+       splay_node_t *node, *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[7];
-       int i;
 
        cp();
 
@@ -252,6 +342,15 @@ void sssp_bfs(void) {
        }
 
        list_free(todo_list);
+}
+
+void check_reachability() {
+       splay_node_t *node, *next;
+       node_t *n;
+       char *name;
+       char *address, *port;
+       char *envp[7];
+       int i;
 
        /* Check reachability status. */
 
@@ -344,6 +443,7 @@ int dump_graph(struct evbuffer *out) {
 }
 
 void graph(void) {
-       sssp_bfs();
+       sssp_dijkstra();
+       check_reachability();
        mst_kruskal();
 }

diff --git a/src/node.c b/src/node.c
index 5ddd8f3..a71a873 100644 (file)
--- a/src/node.c
+++ b/src/node.c
@@ -165,11 +165,11 @@ int dump_nodes(struct evbuffer *out) {
 
        for(node = node_tree->head; node; node = node->next) {
                n = node->data;
-               if(evbuffer_add_printf(out, _(" %s at %s cipher %d digest %d maclength %d compression %d options %lx status %04x nexthop %s via %s pmtu %d (min %d max %d)\n"),
+               if(evbuffer_add_printf(out, _(" %s at %s cipher %d digest %d maclength %d compression %d options %lx status %04x nexthop %s via %s distance %d pmtu %d (min %d max %d)\n"),
                           n->name, n->hostname, cipher_get_nid(&n->cipher),
                           digest_get_nid(&n->digest), n->maclength, n->compression,
                           n->options, *(uint32_t *)&n->status, n->nexthop ? n->nexthop->name : "-",
-                          n->via ? n->via->name : "-", n->mtu, n->minmtu, n->maxmtu) == -1)
+                          n->via ? n->via->name : "-", n->distance, n->mtu, n->minmtu, n->maxmtu) == -1)
                        return errno;
        }
 

diff --git a/src/node.h b/src/node.h
index fee6859..da5081b 100644 (file)
--- a/src/node.h
+++ b/src/node.h
@@ -60,6 +60,7 @@ typedef struct node_t {
 
        list_t *queue;                          /* Queue for packets awaiting to be encrypted */
 
+       int distance;
        struct node_t *nexthop;                 /* nearest node from us to him */
        struct node_t *via;                     /* next hop for UDP packets */