/*
graph.c -- graph algorithms
- Copyright (C) 2001 Guus Sliepen <guus@sliepen.warande.net>,
- 2001 Ivo Timmermans <itimmermans@bigfoot.com>
+ Copyright (C) 2001-2003 Guus Sliepen <guus@sliepen.eu.org>,
+ 2001-2003 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 1.1.2.3 2001/10/29 13:14:57 guus Exp $
+ $Id: graph.c,v 1.1.2.30 2003/10/10 16:23:30 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, adding safe edges until #edges = #nodes - 1.
+ 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.
-*/
-#include <syslog.h>
-#include "config.h"
-#include <string.h>
+ 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.
+*/
-#include <avl_tree.h>
+#include "system.h"
-#include "node.h"
-#include "edge.h"
+#include "avl_tree.h"
#include "connection.h"
-
-#include "system.h"
+#include "device.h"
+#include "edge.h"
+#include "logger.h"
+#include "netutl.h"
+#include "node.h"
+#include "process.h"
+#include "utils.h"
/* Implementation of Kruskal's algorithm.
Running time: O(EN)
void mst_kruskal(void)
{
- avl_node_t *node;
- edge_t *e;
- node_t *n;
- connection_t *c;
- int nodes = 0;
- int safe_edges = 0;
- int skipped;
+ avl_node_t *node, *next;
+ edge_t *e;
+ node_t *n;
+ connection_t *c;
+ int nodes = 0;
+ int safe_edges = 0;
+ bool skipped;
+
+ cp();
+
+ /* 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? */
- syslog(LOG_DEBUG, _("Running Kruskal's algorithm:"));
+ if(!edge_weight_tree->head)
+ return;
- /* Clear visited status on nodes */
+ ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Running Kruskal's algorithm:");
- for(node = node_tree->head; node; node = node->next)
- {
- n = (node_t *)node->data;
- n->status.visited = 0;
- nodes++;
- }
+ /* Clear visited status on nodes */
- /* Starting point */
-
- ((edge_t *)edge_weight_tree->head->data)->from->status.visited = 1;
+ for(node = node_tree->head; node; node = node->next) {
+ n = node->data;
+ n->status.visited = false;
+ nodes++;
+ }
- /* Clear MST status on connections */
+ /* Starting point */
- for(node = connection_tree->head; node; node = node->next)
- {
- c = (connection_t *)node->data;
- c->status.mst = 0;
- }
+ ((edge_t *) edge_weight_tree->head->data)->from->status.visited = true;
- /* Add safe edges */
+ /* Add safe edges */
- while(safe_edges < nodes - 1)
- for(skipped = 0, node = edge_weight_tree->head; node; node = node->next)
- {
-// Algorithm should work without this:
-// if(safe_edges = nodes - 1)
-// break;
+ for(skipped = false, node = edge_weight_tree->head; node; node = next) {
+ next = node->next;
+ e = node->data;
- e = (edge_t *)node->data;
+ if(!e->reverse || e->from->status.visited == e->to->status.visited) {
+ skipped = true;
+ continue;
+ }
- if(e->from->status.visited == e->to->status.visited)
- {
- skipped = 1;
- continue;
- }
+ e->from->status.visited = true;
+ e->to->status.visited = true;
- e->from->status.visited = 1;
- e->to->status.visited = 1;
- if(e->connection)
- e->connection->status.mst = 1;
+ if(e->connection)
+ e->connection->status.mst = true;
- safe_edges++;
+ if(e->reverse->connection)
+ e->reverse->connection->status.mst = true;
- syslog(LOG_DEBUG, _("Adding safe edge %s - %s weight %d"), e->from->name, e->to->name, e->weight);
+ safe_edges++;
- if(skipped)
- break;
- }
+ ifdebug(SCARY_THINGS) logger(LOG_DEBUG, " Adding edge %s - %s weight %d", e->from->name,
+ e->to->name, e->weight);
- syslog(LOG_DEBUG, _("Done."));
+ if(skipped) {
+ skipped = false;
+ next = edge_weight_tree->head;
+ continue;
+ }
+ }
- if(safe_edges != nodes - 1)
- {
- syslog(LOG_ERR, _("Implementation of Kruskal's algorithm is screwed: %d nodes, found %d safe edges"), nodes, safe_edges);
- }
+ 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.
void sssp_bfs(void)
{
- avl_node_t *node, *from, *next, *to;
- edge_t *e;
- node_t *n, *check;
- int nodes = 0;
- int visited = 0;
- avl_tree_t *todo_tree;
-
- syslog(LOG_DEBUG, _("Running BFS algorithm:"));
-
- 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;
- nodes++;
- }
-
- /* 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);
- visited++;
-
- /* Loop while todo_tree is filled */
-
- while(todo_tree->head)
- {
- for(from = todo_tree->head; from; from = next)
- {
- next = from->next;
- n = (node_t *)from->data;
-
- for(to = n->edge_tree->head; to; to = to->next)
- {
- e = (edge_t *)to->data;
-
- if(e->from == n)
- check = e->to;
- else
- check = e->from;
-
- if(!check->status.visited)
- {
- check->status.visited = 1;
- check->nexthop = (n->nexthop == myself) ? n : n->nexthop;
- check->via = check; /* FIXME: only if !(e->options & INDIRECT), otherwise use n->via */
- node = avl_alloc_node();
- node->data = check;
- avl_insert_before(todo_tree, from, node);
- visited++;
- syslog(LOG_DEBUG, _("Node %s nexthop %s via %s"), check->name, check->nexthop->name, check->via->name);
- }
- }
-
- avl_delete_node(todo_tree, from);
- }
- }
-
- syslog(LOG_DEBUG, _("Done."));
-
- avl_free_tree(todo_tree);
-
- if(visited != nodes)
- {
- syslog(LOG_ERR, _("Implementation of BFS algorithm is screwed: %d nodes, visited %d"), nodes, visited);
- }
+ avl_node_t *node, *from, *next, *to;
+ edge_t *e;
+ node_t *n;
+ avl_tree_t *todo_tree;
+ bool 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->data;
+ n->status.visited = false;
+ n->status.indirect = true;
+ }
+
+ /* Begin with myself */
+
+ myself->status.visited = true;
+ myself->status.indirect = false;
+ 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 = 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 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 = true;
+ 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);
+ 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);
+ 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->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);
+ }
+
+ n->status.validkey = false;
+ n->status.waitingforkey = false;
+
+ asprintf(&envp[0], "NETNAME=%s", netname ? : "");
+ asprintf(&envp[1], "DEVICE=%s", device ? : "");
+ asprintf(&envp[2], "INTERFACE=%s", iface ? : "");
+ 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();
}
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