- More s/vertex/edge/g

- Implementation of Kruskal's minimum spanning tree algorithm.

src/Makefile.am

@@ -1,15 +1,15 @@
 ## Produce this file with automake to get Makefile.in
-# $Id: Makefile.am,v 1.4.4.15 2001/10/28 08:41:19 guus Exp $
+# $Id: Makefile.am,v 1.4.4.16 2001/10/28 10:16:18 guus Exp $
 
 sbin_PROGRAMS = tincd
 
-tincd_SOURCES = conf.c connection.c device.c meta.c net.c netutl.c node.c process.c	\
+tincd_SOURCES = conf.c connection.c device.c edge.c graph.c meta.c net.c netutl.c node.c process.c	\
-	protocol.c route.c subnet.c tincd.c edge.c
+	protocol.c route.c subnet.c tincd.c
 
 INCLUDES = @INCLUDES@ -I$(top_builddir) -I$(top_srcdir)/lib -I$(top_srcdir)/intl
 
-noinst_HEADERS = conf.h connection.h device.h meta.h net.h netutl.h node.h process.h	\
+noinst_HEADERS = conf.h connection.h device.h edge.h meta.h net.h netutl.h node.h process.h	\
-	protocol.h route.h subnet.h edge.h
+	protocol.h route.h subnet.h
 
 LIBS = @LIBS@ @INTLLIBS@
 

src/connection.h

@@ -17,7 +17,7 @@
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
-    $Id: connection.h,v 1.1.2.18 2001/10/28 08:41:19 guus Exp $
+    $Id: connection.h,v 1.1.2.19 2001/10/28 10:16:18 guus Exp $
 */
 
 #ifndef __TINC_CONNECTION_H__
@@ -56,7 +56,8 @@ typedef struct connection_status_t {
   int timeout:1;                   /* 1 if gotten timeout */
   int encryptout:1;		   /* 1 if we can encrypt outgoing traffic */
   int decryptin:1;                 /* 1 if we have to decrypt incoming traffic */
-  int unused:18;
+  int mst:1;			   /* 1 if this connection is part of a minimum spanning tree */
+  int unused:17;
 } connection_status_t;
 
 typedef struct connection_t {

src/edge.c

@@ -17,7 +17,7 @@
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
-    $Id: edge.c,v 1.1.2.1 2001/10/28 08:41:19 guus Exp $
+    $Id: edge.c,v 1.1.2.2 2001/10/28 10:16:18 guus Exp $
 */
 
 #include "config.h"
@@ -39,7 +39,8 @@
 #include "xalloc.h"
 #include "system.h"
 
-avl_tree_t *edge_tree;        /* Tree with all known vertices (replaces active_tree) */
+avl_tree_t *edge_tree;        /* Tree with all known edges (replaces active_tree) */
+avl_tree_t *edge_weight_tree; /* Tree with all edges, sorted on weight */
 
 int edge_compare(edge_t *a, edge_t *b)
 {
@@ -64,14 +65,44 @@ int edge_compare(edge_t *a, edge_t *b)
 
 */
 
-void init_vertices(void)
+int edge_weight_compare(edge_t *a, edge_t *b)
+{
+  int result;
+  char *name_a1, *name_a2, *name_b1, *name_b2;
+  
+  
+  result = a->weight - b->weight;
+  
+  if(result)
+    return result;
+
+  if(strcmp(a->from->name, a->to->name) < 0)
+    name_a1 = a->from->name, name_a2 = a->to->name;
+  else
+    name_a1 = a->to->name, name_a2 = a->from->name;
+
+  if(strcmp(b->from->name, b->to->name) < 0)
+    name_b1 = b->from->name, name_b2 = b->to->name;
+  else
+    name_b1 = b->to->name, name_b2 = b->from->name;
+
+  result = strcmp(name_a1, name_b1);
+  
+  if(result)
+    return result;
+  else
+    return strcmp(name_a2, name_b2);
+}
+
+void init_edges(void)
 {
 cp
   edge_tree = avl_alloc_tree((avl_compare_t)edge_compare, NULL);
+  edge_weight_tree = avl_alloc_tree((avl_compare_t)edge_weight_compare, NULL);
 cp
 }
 
-void exit_vertices(void)
+void exit_edges(void)
 {
 cp
   avl_delete_tree(edge_tree);
@@ -83,29 +114,31 @@ cp
 edge_t *new_edge(void)
 {
 cp
-  edge_t *v = (edge_t *)xmalloc_and_zero(sizeof(*v));
+  edge_t *e = (edge_t *)xmalloc_and_zero(sizeof(*e));
 cp
-  return v;
+  return e;
 }
 
-void free_edge(edge_t *v)
+void free_edge(edge_t *e)
 {
 cp
-  free(v);
+  free(e);
 cp
 }
 
-void edge_add(edge_t *v)
+void edge_add(edge_t *e)
 {
 cp
-  avl_insert(edge_tree, v);
+  avl_insert(edge_tree, e);
+  avl_insert(edge_weight_tree, e);
 cp
 }
 
-void edge_del(edge_t *v)
+void edge_del(edge_t *e)
 {
 cp
-  avl_delete(edge_tree, v);
+  avl_delete(edge_tree, e);
+  avl_delete(edge_weight_tree, e);
 cp
 }
 
@@ -127,20 +160,20 @@ cp
   return avl_search(edge_tree, &v);
 }
 
-void dump_vertices(void)
+void dump_edges(void)
 {
   avl_node_t *node;
-  edge_t *v;
+  edge_t *e;
 cp
-  syslog(LOG_DEBUG, _("Vertices:"));
+  syslog(LOG_DEBUG, _("Edges:"));
 
   for(node = edge_tree->head; node; node = node->next)
     {
-      v = (edge_t *)node->data;
+      e = (edge_t *)node->data;
       syslog(LOG_DEBUG, _(" %s - %s options %ld"),
-             v->from->name, v->to->name, v->options);
+             e->from->name, e->to->name, e->options);
     }
     
-  syslog(LOG_DEBUG, _("End of vertices."));
+  syslog(LOG_DEBUG, _("End of edges."));
 cp
 }

src/edge.h

@@ -17,7 +17,7 @@
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
-    $Id: edge.h,v 1.1.2.1 2001/10/28 08:41:19 guus Exp $
+    $Id: edge.h,v 1.1.2.2 2001/10/28 10:16:18 guus Exp $
 */
 
 #ifndef __TINC_EDGE_H__
@@ -42,21 +42,22 @@ typedef struct edge_t {
   struct node_t *from;
   struct node_t *to;
 
-  long int options;                /* options turned on for this connection */
+  long int options;                /* options turned on for this edge */
-  int metric;                      /* weight of this edge */
+  int weight;                      /* weight of this edge */
   
   struct connection_t *connection; /* connection associated with this edge, if available */
 } edge_t;
 
-extern avl_tree_t *edge_tree;    /* Tree with all known vertices (replaces active_tree) */
+extern avl_tree_t *edge_tree;    /* Tree with all known edges (replaces active_tree) */
+extern avl_tree_t *edge_weight_tree; /* Tree with all known edges sorted on weight */
 
-extern void init_vertices(void);
+extern void init_edges(void);
-extern void exit_vertices(void);
+extern void exit_edges(void);
 extern edge_t *new_edge(void);
 extern void free_edge(edge_t *);
 extern void edge_add(edge_t *);
 extern void edge_del(edge_t *);
 extern edge_t *lookup_edge(struct node_t *, struct node_t *);
-extern void dump_vertices(void);
+extern void dump_edges(void);
 
 #endif /* __TINC_EDGE_H__ */

src/graph.c

@@ -0,0 +1,111 @@
+/*
+    graph.c -- graph algorithms
+    Copyright (C) 2001 Guus Sliepen <guus@sliepen.warande.net>,
+                  2001 Ivo Timmermans <itimmermans@bigfoot.com>
+
+    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 1.1.2.1 2001/10/28 10:16:18 guus 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.
+
+   For the SSSP algorithm Dijkstra's seems to be a nice choice.
+*/
+
+#include <syslog.h>
+#include "config.h"
+
+#include "node.h"
+#include "edge.h"
+#include "connection.h"
+
+#include "system.h"
+
+/* Implementation of Kruskal's algorithm.
+   Running time: O(V)
+   Please note that sorting on weight is already done by add_vertex().
+*/
+
+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);
+    }
+}

src/net.c

@@ -17,7 +17,7 @@
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
-    $Id: net.c,v 1.35.4.140 2001/10/28 08:41:19 guus Exp $
+    $Id: net.c,v 1.35.4.141 2001/10/28 10:16:18 guus Exp $
 */
 
 #include "config.h"
@@ -776,7 +776,7 @@ cp
   init_connections();
   init_subnets();
   init_nodes();
-  init_vertices();
+  init_edges();
 
   if(get_config_int(lookup_config(config_tree, "PingTimeout"), &timeout))
     {

src/node.h

@@ -17,7 +17,7 @@
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
-    $Id: node.h,v 1.1.2.5 2001/10/27 12:13:17 guus Exp $
+    $Id: node.h,v 1.1.2.6 2001/10/28 10:16:18 guus Exp $
 */
 
 #ifndef __TINC_NODE_H__
@@ -32,7 +32,8 @@ typedef struct node_status_t {
   int active:1;                    /* 1 if active.. */
   int validkey:1;                  /* 1 if we currently have a valid key for him */
   int waitingforkey:1;             /* 1 if we already sent out a request */
-  int unused:29;
+  int mst:1;                       /* 1 if this node has been visited by the MST algorithm */
+  int unused:28;
 } node_status_t;
 
 typedef struct node_t {

src/process.c

@@ -17,7 +17,7 @@
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
-    $Id: process.c,v 1.1.2.28 2001/10/27 15:19:13 guus Exp $
+    $Id: process.c,v 1.1.2.29 2001/10/28 10:16:18 guus Exp $
 */
 
 #include "config.h"
@@ -380,7 +380,7 @@ sigusr2_handler(int a, siginfo_t *info, void *b)
 {
   dump_device_stats();
   dump_nodes();
-  dump_vertices();
+  dump_edges();
   dump_subnets();
 }
 

src/protocol.c

@@ -17,7 +17,7 @@
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
-    $Id: protocol.c,v 1.28.4.110 2001/10/28 08:41:19 guus Exp $
+    $Id: protocol.c,v 1.28.4.111 2001/10/28 10:16:18 guus Exp $
 */
 
 #include "config.h"
@@ -600,7 +600,7 @@ cp
   
   c->edge->from = myself;
   c->edge->to = n;
-  c->edge->metric = 1;
+  c->edge->weight = 1;
   c->edge->connection = c;
 
   edge_add(c->edge);
@@ -934,19 +934,19 @@ cp
   return 0;
 }
 
-/* Vertices */
+/* Edges */
 
-int send_add_edge(connection_t *c, edge_t *v)
+int send_add_edge(connection_t *c, edge_t *e)
 {
 cp
   return send_request(c, "%d %s %s %lx", ADD_NODE,
-                      v->from->name, v->to->name, v->options);
+                      e->from->name, e->to->name, e->options);
 }
 
 int add_edge_h(connection_t *c)
 {
   connection_t *other;
-  edge_t *v;
+  edge_t *e;
   node_t *from, *to;
   char from_name[MAX_STRING_SIZE];
   char to_name[MAX_STRING_SIZE];
@@ -993,19 +993,19 @@ cp
 
   /* Check if node already exists */
   
-  v = lookup_edge(from, to);
+  e = lookup_edge(from, to);
   
-  if(v)
+  if(e)
     {
       /* Check if it matches */
     }
   else
     {
-      v = new_edge();
+      e = new_edge();
-      v->from = from;
+      e->from = from;
-      v->to = to;
+      e->to = to;
-      v->options = options;
+      e->options = options;
-      edge_add(v);
+      edge_add(e);
     }
 
   /* Tell the rest about the new edge */
@@ -1014,23 +1014,23 @@ cp
     {
       other = (connection_t *)node->data;
       if(other->status.active && other != c)
-        send_add_edge(other, v);
+        send_add_edge(other, e);
     }
 
 cp
   return 0;
 }
 
-int send_del_edge(connection_t *c, edge_t *v)
+int send_del_edge(connection_t *c, edge_t *e)
 {
 cp
   return send_request(c, "%d %s %s %lx", DEL_EDGE,
-                      v->from->name, v->to->name, v->options);
+                      e->from->name, e->to->name, e->options);
 }
 
 int del_edge_h(connection_t *c)
 {
-  edge_t *v;
+  edge_t *e;
   char from_name[MAX_STRING_SIZE];
   char to_name[MAX_STRING_SIZE];
   node_t *from, *to;
@@ -1079,9 +1079,9 @@ cp
 
   /* Check if edge exists */
   
-  v = lookup_edge(from, to);
+  e = lookup_edge(from, to);
   
-  if(v)
+  if(e)
     {
       /* Check if it matches */
     }
@@ -1097,12 +1097,12 @@ cp
     {
       other = (connection_t *)node->data;
       if(other->status.active && other != c)
-        send_del_edge(other, v);
+        send_del_edge(other, e);
     }
 
   /* Delete the edge */
   
-  edge_del(v);
+  edge_del(e);
 cp
   return 0;
 }