/*
graph.c -- graph algorithms
- Copyright (C) 2001 Guus Sliepen <guus@sliepen.warande.net>,
- 2001 Ivo Timmermans <itimmermans@bigfoot.com>
+ Copyright (C) 2001-2013 Guus Sliepen <guus@tinc-vpn.org>,
+ 2001-2005 Ivo Timmermans
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 1.1.2.1 2001/10/28 10:16:18 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:
1. A minimum spanning tree for broadcasts,
2. A single-source shortest path tree for unicasts.
-
+
Actually, the first one alone would suffice but would make unicast packets
take longer routes than necessary.
-
+
For the MST algorithm we can choose from Prim's or Kruskal's. I personally
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.
+ 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.
*/
-#include <syslog.h>
-#include "config.h"
+#include "system.h"
-#include "node.h"
-#include "edge.h"
+#include "avl_tree.h"
+#include "conf.h"
#include "connection.h"
+#include "device.h"
+#include "edge.h"
+#include "graph.h"
+#include "logger.h"
+#include "netutl.h"
+#include "node.h"
+#include "process.h"
+#include "protocol.h"
+#include "subnet.h"
+#include "utils.h"
+#include "xalloc.h"
-#include "system.h"
+static bool graph_changed = true;
/* Implementation of Kruskal's algorithm.
- Running time: O(V)
- Please note that sorting on weight is already done by add_vertex().
+ 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;
+
+ // Only update nexthop the first time we visit this node.
+
+ if(!e->to->status.visited)
+ e->to->nexthop = (n->nexthop == myself) ? e->to : n->nexthop;
+
+ e->to->status.visited = true;
+ e->to->status.indirect = indirect;
+ 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
*/
-void kruskal(void)
-{
- avl_node_t *node;
- edge_t *e;
- node_t *n;
- connection_t *c;
- int nodes;
- int safe_edges = 0;
-
- syslog(LOG_DEBUG, _("Running Kruskal's algorithm:"));
-
- /* Clear MST status on nodes */
-
- for(node = node_tree->head; node; node = node->next)
- {
- n = (node_t *)node->data;
- n->status.mst = 0;
- node++;
- }
-
- /* Clear MST status on connections */
-
- for(node = connection_tree->head; node; node = node->next)
- {
- c = (edge_t *)node->data;
- c->status.mst = 0;
- }
-
- /* Add safe edges */
-
- for(node = edge_weight_tree->head; node; node = node->next)
- {
-// Algorithm should work without this:
-// if(safe_edges = nodes - 1)
-// break;
-
- e = (edge_t *)node->data;
-
- if(e->from->status.mst && e->to->status.mst)
- continue;
-
- e->from->status.mst = 1;
- e->to->status.mst = 1;
- if(e->connection)
- e->connection->status.mst = 1;
-
- safe_edges++;
-
- syslog(LOG_DEBUG, _("Adding safe edge %s - %s weight %d"), e->from->name, e->to->name, e->weight);
- }
-
- syslog(LOG_DEBUG, _("Done."));
-
- if(safe_edges != nodes - 1)
- {
- syslog(LOG_ERR, _("Implementation of Kruskal's algorithm is screwed: %d nodes, found %d safe edges"), nodes, safe_edges);
- }
+void dump_graph(void) {
+ avl_node_t *node;
+ node_t *n;
+ edge_t *e;
+ char *filename = NULL, *tmpname = NULL;
+ FILE *file, *pipe = NULL;
+
+ if(!graph_changed || !get_config_string(lookup_config(config_tree, "GraphDumpFile"), &filename))
+ return;
+
+ graph_changed = false;
+
+ ifdebug(PROTOCOL) logger(LOG_NOTICE, "Dumping graph");
+
+ if(filename[0] == '|') {
+ file = pipe = popen(filename + 1, "w");
+ } else {
+ xasprintf(&tmpname, "%s.new", filename);
+ file = fopen(tmpname, "w");
+ }
+
+ if(!file) {
+ logger(LOG_ERR, "Unable to open graph dump file %s: %s", filename, strerror(errno));
+ free(tmpname);
+ return;
+ }
+
+ fprintf(file, "digraph {\n");
+
+ /* dump all nodes first */
+ for(node = node_tree->head; node; node = node->next) {
+ n = node->data;
+ fprintf(file, " %s [label = \"%s\"];\n", n->name, n->name);
+ }
+
+ /* now dump all edges */
+ for(node = edge_weight_tree->head; node; node = node->next) {
+ e = node->data;
+ fprintf(file, " %s -> %s;\n", e->from->name, e->to->name);
+ }
+
+ fprintf(file, "}\n");
+
+ if(pipe) {
+ pclose(pipe);
+ } else {
+ fclose(file);
+#ifdef HAVE_MINGW
+ unlink(filename);
+#endif
+ rename(tmpname, filename);
+ free(tmpname);
+ }
}
projects / tinc / blobdiff