X-Git-Url: https://www.tinc-vpn.org/git/browse?p=tinc;a=blobdiff_plain;f=lib%2Fgraph.c;fp=lib%2Fgraph.c;h=0000000000000000000000000000000000000000;hp=f953263212c650fa726954ccaaa064c826641602;hb=013a2e159e42c46808ea8d0b6abd57525db30a50;hpb=efa5148bc76effb440d807d653dda02de050fde0 diff --git a/lib/graph.c b/lib/graph.c deleted file mode 100644 index f9532632..00000000 --- a/lib/graph.c +++ /dev/null @@ -1,285 +0,0 @@ -/* - graph.c -- graph algorithms - Copyright (C) 2001-2002 Guus Sliepen , - 2001-2002 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 - the Free Software Foundation; either version 2 of the License, or - (at your option) any later version. - - This program is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - 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 2002/05/02 11:50:07 zarq Exp $ -*/ - -/* 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. 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. -*/ - -#include "config.h" - -#include -#include -#include -#if defined(HAVE_FREEBSD) || defined(HAVE_OPENBSD) - #include -#endif -#include - -#include -#include -#include - -#include "netutl.h" -#include "node.h" -#include "edge.h" -#include "connection.h" -#include "logging.h" - -#include "system.h" - -/* 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, *next; - edge_t *e; - node_t *n; - connection_t *c; - int nodes = 0; - int safe_edges = 0; - int skipped; - - /* 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.node->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->from.node->status.visited == e->to.node->status.visited) - { - skipped = 1; - continue; - } - - e->from.node->status.visited = 1; - e->to.node->status.visited = 1; - if(e->connection) - e->connection->status.mst = 1; - - safe_edges++; - - if(debug_lvl >= DEBUG_SCARY_THINGS) - syslog(LOG_DEBUG, " Adding edge %s - %s weight %d", e->from.node->name, e->to.node->name, e->weight); - - if(skipped) - { - 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. - 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; - int indirect; - - 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; - } - - /* 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->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; - - /* Situation: - - / - / - ------(n)from_hc-----to_hc - \ - \ - - n->address is set to the to_hc.udpaddress of the edge left of n. - We are currently examining the edge right of n: - - - If from_hc.udpaddress != n->address, then to_hc.node 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 to_hc.node, update - to_hc.node 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, &from_hc.udpaddress)); - - if(to_hc.node->status.visited && (!to_hc.node->status.indirect || indirect)) - continue; - - to_hc.node->status.visited = 1; - to_hc.node->status.indirect = indirect; - to_hc.node->nexthop = (n->nexthop == myself) ? to_hc.node : n->nexthop; - to_hc.node->via = indirect ? 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; - run_hooks("node-visible", n); - } - } - 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; - run_hooks("node-invisible", n); - } - } - } -} - -void graph(void) -{ - mst_kruskal(); - sssp_bfs(); -}