/*
graph.c -- graph algorithms
- Copyright (C) 2001-2002 Guus Sliepen <guus@sliepen.warande.net>,
- 2001-2002 Ivo Timmermans <itimmermans@bigfoot.com>
+ Copyright (C) 2014 Guus Sliepen <guus@meshlink.io>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software
- Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-
- $Id: graph.c,v 1.1.2.8 2002/03/12 13:42:23 guus Exp $
+ You should have received a copy of the GNU General Public License along
+ with this program; if not, write to the Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/* We need to generate two trees from the graph:
favour Kruskal's, because we make an extra AVL tree of edges sorted on
weights (metric). That tree only has to be updated when an edge is added or
removed, and during the MST algorithm we just have go linearly through that
- tree.
+ tree, adding safe edges until #edges = #nodes - 1. The implementation here
+ however is not so fast, because I tried to avoid having to make a forest and
+ merge trees.
For the SSSP algorithm Dijkstra's seems to be a nice choice. Currently a
simple breadth-first search is presented here.
- The SSSP algorithm will also be used to determine whether nodes are directly,
- indirectly or not reachable from the source. It will also set the correct
- destination address and port of a node if possible.
+ The SSSP algorithm will also be used to determine whether nodes are
+ reachable from the source. It will also set the correct destination address
+ and port of a node if possible.
*/
-#include <syslog.h>
-#include "config.h"
-#include <string.h>
-#if defined(HAVE_FREEBSD) || defined(HAVE_OPENBSD)
- #include <sys/param.h>
-#endif
-#include <netinet/in.h>
-
-#include <avl_tree.h>
-#include <utils.h>
+#include "system.h"
+#include "connection.h"
+#include "edge.h"
+#include "graph.h"
+#include "list.h"
+#include "logger.h"
+#include "meshlink_internal.h"
#include "netutl.h"
#include "node.h"
-#include "edge.h"
-#include "connection.h"
+#include "protocol.h"
+#include "utils.h"
+#include "xalloc.h"
+#include "graph.h"
+
+/* Implementation of Kruskal's algorithm.
+ Running time: O(EN)
+ Please note that sorting on weight is already done by add_edge().
+*/
-#include "system.h"
+static void mst_kruskal(meshlink_handle_t *mesh) {
+ /* Clear MST status on connections */
-/* Kruskal's minimum spanning tree algorithm.
- Running time: O(E)
- Edges are already sorted on weight.
-*/
+ for list_each(connection_t, c, mesh->connections) {
+ c->status.mst = false;
+ }
-void mst_kruskal(void)
-{
- avl_node_t *node;
- edge_t *e;
- node_t *n;
- connection_t *c;
+ logger(mesh, MESHLINK_DEBUG, "Running Kruskal's algorithm:");
- /* Clear MST status on connections */
+ /* Clear visited status on nodes */
- for(node = connection_tree->head; node; node = node->next)
- {
- c = (connection_t *)node->data;
- c->status.mst = 0;
- }
+ for splay_each(node_t, n, mesh->nodes) {
+ n->status.visited = false;
+ }
- /* Do we have something to do at all? */
-
- if(!edge_weight_tree->head)
- return;
+ /* Starting point */
+
+ for splay_each(edge_t, e, mesh->edges) {
+ if(e->from->status.reachable) {
+ e->from->status.visited = true;
+ break;
+ }
+ }
- /* Clear visited status on nodes */
+ /* Add safe edges */
- for(node = node_tree->head; node; node = node->next)
- {
- n = (node_t *)node->data;
- n->status.visited = 0;
- }
+ bool skipped = false;
- /* Starting point */
-
- ((edge_t *)edge_weight_tree->head->data)->from.node->status.visited = 1;
+ for splay_each(edge_t, e, mesh->edges) {
+ if(!e->reverse || (e->from->status.visited == e->to->status.visited)) {
+ skipped = true;
+ continue;
+ }
- /* Add safe edges */
+ e->from->status.visited = true;
+ e->to->status.visited = true;
- for(node = edge_weight_tree->head; node; node = node->next)
- {
- e = (edge_t *)node->data;
+ if(e->connection) {
+ e->connection->status.mst = true;
+ }
- if(e->from.node->status.visited && e->to.node->status.visited)
- continue;
+ if(e->reverse->connection) {
+ e->reverse->connection->status.mst = true;
+ }
- e->from.node->status.visited = 1;
- e->to.node->status.visited = 1;
- if(e->connection)
- e->connection->status.mst = 1;
- }
+ logger(mesh, MESHLINK_DEBUG, " Adding edge %s - %s weight %d", e->from->name, e->to->name, e->weight);
+
+ if(skipped) {
+ skipped = false;
+ next = mesh->edges->head;
+ }
+ }
}
/* Implementation of a simple breadth-first search algorithm.
Running time: O(E)
*/
-void sssp_bfs(void)
-{
- avl_node_t *node, *from, *next, *to;
- edge_t *e;
- node_t *n;
- halfconnection_t to_hc, from_hc;
- avl_tree_t *todo_tree;
-
- todo_tree = avl_alloc_tree(NULL, NULL);
-
- /* Clear visited status on nodes */
-
- for(node = node_tree->head; node; node = node->next)
- {
- n = (node_t *)node->data;
- n->status.visited = 0;
- }
-
- /* Begin with myself */
-
- myself->status.visited = 1;
- myself->nexthop = myself;
- myself->via = myself;
- node = avl_alloc_node();
- node->data = myself;
- avl_insert_top(todo_tree, node);
-
- /* Loop while todo_tree is filled */
-
- while(todo_tree->head)
- {
- for(from = todo_tree->head; from; from = next) /* "from" is the node from which we start */
- {
- next = from->next;
- n = (node_t *)from->data;
-
- for(to = n->edge_tree->head; to; to = to->next) /* "to" is the edge connected to "from" */
- {
- e = (edge_t *)to->data;
-
- if(e->from.node == n) /* "from_hc" is the halfconnection with .node == from */
- to_hc = e->to, from_hc = e->from;
- else
- to_hc = e->from, from_hc = e->to;
-
- if(!to_hc.node->status.visited)
- {
- to_hc.node->status.visited = 1;
- to_hc.node->nexthop = (n->nexthop == myself) ? to_hc.node : n->nexthop;
- to_hc.node->via = (e->options & OPTION_INDIRECT || n->via != n) ? n->via : to_hc.node;
- to_hc.node->options = e->options;
- if(sockaddrcmp(&to_hc.node->address, &to_hc.udpaddress))
- {
- node = avl_unlink(node_udp_tree, to_hc.node);
- to_hc.node->address = to_hc.udpaddress;
- if(to_hc.node->hostname)
- free(to_hc.node->hostname);
- to_hc.node->hostname = sockaddr2hostname(&to_hc.udpaddress);
- avl_insert_node(node_udp_tree, node);
- }
- node = avl_alloc_node();
- node->data = to_hc.node;
- avl_insert_before(todo_tree, from, node);
- }
- }
-
- avl_delete_node(todo_tree, from);
- }
- }
-
- avl_free_tree(todo_tree);
-
- /* Check reachability status. */
-
- for(node = node_tree->head; node; node = next)
- {
- next = node->next;
- n = (node_t *)node->data;
-
- if(n->status.visited)
- {
- if(!n->status.reachable)
- {
- if(debug_lvl >= DEBUG_TRAFFIC)
- syslog(LOG_DEBUG, _("Node %s (%s) became reachable"), n->name, n->hostname);
- n->status.reachable = 1;
+static void sssp_bfs(meshlink_handle_t *mesh) {
+ list_t *todo_list = list_alloc(NULL);
+
+ /* Clear visited status on nodes */
+
+ for splay_each(node_t, n, mesh->nodes) {
+ n->status.visited = false;
+ n->distance = -1;
}
- }
- else
- {
- if(n->status.reachable)
- {
- if(debug_lvl >= DEBUG_TRAFFIC)
- syslog(LOG_DEBUG, _("Node %s (%s) became unreachable"), n->name, n->hostname);
- n->status.reachable = 0;
- n->status.validkey = 0;
- n->status.waitingforkey = 0;
- n->sent_seqno = 0;
+
+ /* Begin with mesh->self */
+
+ mesh->self->status.visited = true;
+ 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. */
+
+ for splay_each(node_t, n, mesh->nodes) {
+ if(n->status.visited != n->status.reachable) {
+ n->status.reachable = !n->status.reachable;
+ n->last_state_change = mesh->loop.now.tv_sec;
+
+ if(n->status.reachable) {
+ logger(mesh, MESHLINK_DEBUG, "Node %s became reachable", n->name);
+ } else {
+ logger(mesh, MESHLINK_DEBUG, "Node %s became unreachable", n->name);
+ }
+
+ /* 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);
+ }
+ }
}
- }
- }
}
-void graph(void)
-{
- mst_kruskal();
- sssp_bfs();
+void graph(meshlink_handle_t *mesh) {
+ sssp_bfs(mesh);
+ check_reachability(mesh);
+ mst_kruskal(mesh);
}
projects / meshlink / blobdiff