/*
graph.c -- graph algorithms
- Copyright (C) 2001-2002 Guus Sliepen <guus@sliepen.warande.net>,
- 2001-2002 Ivo Timmermans <itimmermans@bigfoot.com>
+ Copyright (C) 2001-2002 Guus Sliepen <guus@sliepen.eu.org>,
+ 2001-2002 Ivo Timmermans <ivo@o2w.nl>
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
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 $
+ $Id: graph.c,v 1.1.2.20 2002/09/10 09:40:21 guus Exp $
*/
/* 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.
destination address and port of a node if possible.
*/
+#include "config.h"
+
+#include <stdio.h>
#include <syslog.h>
#include "config.h"
#include <string.h>
-#if defined(HAVE_FREEBSD) || defined(HAVE_OPENBSD)
- #include <sys/param.h>
+#ifdef HAVE_SYS_PARAM_H
+#include <sys/param.h>
#endif
#include <netinet/in.h>
#include "node.h"
#include "edge.h"
#include "connection.h"
+#include "process.h"
+#include "device.h"
#include "system.h"
-/* Kruskal's minimum spanning tree algorithm.
- Running time: O(E)
- Edges are already sorted on weight.
+/* Implementation of Kruskal's algorithm.
+ Running time: O(EN)
+ Please note that sorting on weight is already done by add_edge().
*/
void mst_kruskal(void)
{
- avl_node_t *node;
- edge_t *e;
- node_t *n;
- connection_t *c;
-
- /* Clear MST status on connections */
-
- for(node = connection_tree->head; node; node = node->next)
- {
- c = (connection_t *)node->data;
- c->status.mst = 0;
- }
-
- /* Do we have something to do at all? */
-
- if(!edge_weight_tree->head)
- return;
-
- /* Clear visited status on nodes */
-
- for(node = node_tree->head; node; node = node->next)
- {
- n = (node_t *)node->data;
- n->status.visited = 0;
- }
-
- /* Starting point */
-
- ((edge_t *)edge_weight_tree->head->data)->from.node->status.visited = 1;
-
- /* Add safe edges */
-
- for(node = edge_weight_tree->head; node; node = node->next)
- {
- e = (edge_t *)node->data;
-
- if(e->from.node->status.visited && e->to.node->status.visited)
- continue;
-
- e->from.node->status.visited = 1;
- e->to.node->status.visited = 1;
- if(e->connection)
- e->connection->status.mst = 1;
- }
+ avl_node_t *node, *next;
+ edge_t *e;
+ node_t *n;
+ connection_t *c;
+ int nodes = 0;
+ int safe_edges = 0;
+ int skipped;
+
+ cp();
+
+ /* Clear MST status on connections */
+
+ for(node = connection_tree->head; node; node = node->next) {
+ c = (connection_t *) node->data;
+ c->status.mst = 0;
+ }
+
+ /* Do we have something to do at all? */
+
+ if(!edge_weight_tree->head)
+ return;
+
+ if(debug_lvl >= DEBUG_SCARY_THINGS)
+ syslog(LOG_DEBUG, "Running Kruskal's algorithm:");
+
+ /* Clear visited status on nodes */
+
+ for(node = node_tree->head; node; node = node->next) {
+ n = (node_t *) node->data;
+ n->status.visited = 0;
+ nodes++;
+ }
+
+ /* Starting point */
+
+ ((edge_t *) edge_weight_tree->head->data)->from->status.visited = 1;
+
+ /* Add safe edges */
+
+ for(skipped = 0, node = edge_weight_tree->head; node; node = next) {
+ next = node->next;
+ e = (edge_t *) node->data;
+
+ if(!e->reverse || e->from->status.visited == e->to->status.visited) {
+ skipped = 1;
+ continue;
+ }
+
+ e->from->status.visited = 1;
+ e->to->status.visited = 1;
+
+ if(e->connection)
+ e->connection->status.mst = 1;
+
+ if(e->reverse->connection)
+ e->reverse->connection->status.mst = 1;
+
+ safe_edges++;
+
+ if(debug_lvl >= DEBUG_SCARY_THINGS)
+ syslog(LOG_DEBUG, " Adding edge %s - %s weight %d", e->from->name,
+ e->to->name, e->weight);
+
+ if(skipped) {
+ skipped = 0;
+ next = edge_weight_tree->head;
+ continue;
+ }
+ }
+
+ if(debug_lvl >= DEBUG_SCARY_THINGS)
+ syslog(LOG_DEBUG, "Done, counted %d nodes and %d safe edges.", nodes,
+ safe_edges);
}
/* Implementation of a simple breadth-first search algorithm.
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;
+ avl_node_t *node, *from, *next, *to;
+ edge_t *e;
+ node_t *n;
+ avl_tree_t *todo_tree;
+ int indirect;
+ char *name;
+ char *address, *port;
+ char *envp[7];
+ int i;
+
+ cp();
+
+ 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;
+ n->status.indirect = 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 myself */
+
+ myself->status.visited = 1;
+ myself->status.indirect = 0;
+ 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->reverse)
+ continue;
+
+ /* Situation:
+
+ /
+ /
+ ------(n)-----(e->to)
+ \
+ \
+
+ 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 and (re)add it to the todo_tree to (re)examine the reachability
+ of nodes behind it.
+ */
+
+ indirect = n->status.indirect || e->options & OPTION_INDIRECT
+ || ((n != myself)
+ && sockaddrcmp(&n->address, &e->reverse->address));
+
+ if(e->to->status.visited
+ && (!e->to->status.indirect || indirect))
+ continue;
+
+ e->to->status.visited = 1;
+ 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 = avl_unlink(node_udp_tree, e->to);
+ e->to->address = e->address;
+
+ if(e->to->hostname)
+ free(e->to->hostname);
+
+ e->to->hostname = sockaddr2hostname(&e->to->address);
+ avl_insert_node(node_udp_tree, node);
+ }
+
+ node = avl_alloc_node();
+ node->data = e->to;
+ 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 != n->status.reachable) {
+ n->status.reachable = !n->status.reachable;
+
+ if(debug_lvl >= DEBUG_TRAFFIC) {
+ if(n->status.reachable)
+ syslog(LOG_DEBUG, _("Node %s (%s) became reachable"),
+ n->name, n->hostname);
+ else
+ syslog(LOG_DEBUG, _("Node %s (%s) became unreachable"),
+ n->name, n->hostname);
+ }
+
+ n->status.validkey = 0;
+ n->status.waitingforkey = 0;
+
+ asprintf(&envp[0], "NETNAME=%s", netname ? : "");
+ asprintf(&envp[1], "DEVICE=%s", device ? : "");
+ asprintf(&envp[2], "INTERFACE=%s", interface ? : "");
+ asprintf(&envp[3], "NODE=%s", n->name);
+ sockaddr2str(&n->address, &address, &port);
+ asprintf(&envp[4], "REMOTEADDRESS=%s", address);
+ asprintf(&envp[5], "REMOTEPORT=%s", port);
+ envp[6] = NULL;
+
+ asprintf(&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]);
+ }
}
- }
- }
}
void graph(void)
{
- mst_kruskal();
- sssp_bfs();
+ mst_kruskal();
+ sssp_bfs();
}
projects / tinc / blobdiff