From f48f8f4fedba365ceea30e1133bf1c560e9a522a Mon Sep 17 00:00:00 2001
From: Guus Sliepen <guus@tinc-vpn.org>
Date: Tue, 19 Mar 2002 22:48:25 +0000
Subject: [PATCH] Updated SSSP algorithm to automatically detect indirect links
(if a node uses different addresses for connections to other nodes).
---
src/graph.c | 65 ++++++++++++++++++++++++++++++++++++-----------------
src/node.h | 5 +++--
2 files changed, 48 insertions(+), 22 deletions(-)
diff --git a/src/graph.c b/src/graph.c
index dd080c05..29e25db1 100644
--- a/src/graph.c
+++ b/src/graph.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: graph.c,v 1.1.2.9 2002/03/12 16:30:15 guus Exp $
+ $Id: graph.c,v 1.1.2.10 2002/03/19 22:48:25 guus Exp $
*/
/* We need to generate two trees from the graph:
@@ -151,6 +151,7 @@ void sssp_bfs(void)
node_t *n;
halfconnection_t to_hc, from_hc;
avl_tree_t *todo_tree;
+ int indirect;
todo_tree = avl_alloc_tree(NULL, NULL);
@@ -160,11 +161,13 @@ void sssp_bfs(void)
{
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();
@@ -189,25 +192,47 @@ void sssp_bfs(void)
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);
- }
+ /* 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);
diff --git a/src/node.h b/src/node.h
index 64938521..98147d3e 100644
--- a/src/node.h
+++ b/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 1.1.2.12 2002/02/18 16:25:16 guus Exp $
+ $Id: node.h,v 1.1.2.13 2002/03/19 22:48:25 guus Exp $
*/
#ifndef __TINC_NODE_H__
@@ -34,7 +34,8 @@ typedef struct node_status_t {
int waitingforkey:1; /* 1 if we already sent out a request */
int visited:1; /* 1 if this node has been visited by one of the graph algorithms */
int reachable:1; /* 1 if this node is reachable in the graph */
- int unused:27;
+ int indirect:1; /* 1 if this node is not directly reachable by us */
+ int unused:26;
} node_status_t;
typedef struct node_t {