tinc/src/net.c

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/*
net.c -- most of the network code
Copyright (C) 1998-2002 Ivo Timmermans <ivo@o2w.nl>,
2000-2002 Guus Sliepen <guus@sliepen.eu.org>
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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: net.c,v 1.35.4.177 2002/09/04 16:26:44 guus Exp $
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*/
#include "config.h"
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <netinet/in.h>
#ifdef HAVE_NETINET_IN_SYSTM_H
#include <netinet/in_systm.h>
#endif
#ifdef HAVE_NETINET_IP_H
#include <netinet/ip.h>
#endif
#ifdef HAVE_NETINET_TCP_H
#include <netinet/tcp.h>
#endif
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
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#include <signal.h>
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#include <sys/time.h>
#include <sys/types.h>
#include <syslog.h>
#include <unistd.h>
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#include <sys/ioctl.h>
/* SunOS really wants sys/socket.h BEFORE net/if.h,
and FreeBSD wants these lines below the rest. */
#include <arpa/inet.h>
#include <sys/socket.h>
#include <net/if.h>
#include <openssl/rand.h>
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#include <utils.h>
#include <xalloc.h>
#include <avl_tree.h>
#include <list.h>
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#include "conf.h"
#include "connection.h"
#include "meta.h"
#include "net.h"
#include "netutl.h"
#include "process.h"
#include "protocol.h"
#include "subnet.h"
#include "graph.h"
#include "process.h"
#include "route.h"
#include "device.h"
#include "event.h"
#include "system.h"
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#ifndef HAVE_RAND_PSEUDO_BYTES
#define RAND_pseudo_bytes RAND_bytes
#endif
int do_purge = 0;
int sighup = 0;
int sigalrm = 0;
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time_t now = 0;
/* Purge edges and subnets of unreachable nodes. Use carefully. */
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void purge(void)
{
avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
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node_t *n;
edge_t *e;
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subnet_t *s;
cp
if(debug_lvl >= DEBUG_PROTOCOL)
syslog(LOG_DEBUG, _("Purging unreachable nodes"));
for(nnode = node_tree->head; nnode; nnode = nnext)
{
nnext = nnode->next;
n = (node_t *)nnode->data;
if(!n->status.reachable)
{
if(debug_lvl >= DEBUG_SCARY_THINGS)
syslog(LOG_DEBUG, _("Purging node %s (%s)"), n->name, n->hostname);
for(snode = n->subnet_tree->head; snode; snode = snext)
{
snext = snode->next;
s = (subnet_t *)snode->data;
send_del_subnet(broadcast, s);
subnet_del(n, s);
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}
for(enode = n->edge_tree->head; enode; enode = enext)
{
enext = enode->next;
e = (edge_t *)enode->data;
send_del_edge(broadcast, e);
edge_del(e);
}
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node_del(n);
}
}
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cp
}
/*
put all file descriptors in an fd_set array
While we're at it, purge stuff that needs to be removed.
*/
void build_fdset(fd_set *fs)
{
avl_node_t *node, *next;
connection_t *c;
int i;
cp
FD_ZERO(fs);
for(node = connection_tree->head; node; node = next)
{
next = node->next;
c = (connection_t *)node->data;
if(c->status.remove)
{
connection_del(c);
if(!connection_tree->head)
purge();
}
else
FD_SET(c->socket, fs);
}
for(i = 0; i < listen_sockets; i++)
{
FD_SET(listen_socket[i].tcp, fs);
FD_SET(listen_socket[i].udp, fs);
}
FD_SET(device_fd, fs);
cp
}
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/*
Terminate a connection:
- Close the socket
- Remove associated edge and tell other connections about it if report = 1
- Check if we need to retry making an outgoing connection
- Deactivate the host
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*/
void terminate_connection(connection_t *c, int report)
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{
cp
if(c->status.remove)
return;
if(debug_lvl >= DEBUG_CONNECTIONS)
syslog(LOG_NOTICE, _("Closing connection with %s (%s)"),
c->name, c->hostname);
c->status.remove = 1;
c->status.active = 0;
if(c->node)
c->node->connection = NULL;
if(c->socket)
close(c->socket);
if(c->edge)
{
if(report)
send_del_edge(broadcast, c->edge);
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edge_del(c->edge);
/* Run MST and SSSP algorithms */
graph();
}
/* Check if this was our outgoing connection */
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if(c->outgoing)
{
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retry_outgoing(c->outgoing);
c->outgoing = NULL;
}
cp
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}
/*
Check if the other end is active.
If we have sent packets, but didn't receive any,
then possibly the other end is dead. We send a
PING request over the meta connection. If the other
end does not reply in time, we consider them dead
and close the connection.
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*/
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void check_dead_connections(void)
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{
avl_node_t *node, *next;
connection_t *c;
cp
for(node = connection_tree->head; node; node = next)
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{
next = node->next;
c = (connection_t *)node->data;
if(c->last_ping_time + pingtimeout < now)
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{
if(c->status.active)
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{
if(c->status.pinged)
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{
if(debug_lvl >= DEBUG_PROTOCOL)
syslog(LOG_INFO, _("%s (%s) didn't respond to PING"),
c->name, c->hostname);
c->status.timeout = 1;
terminate_connection(c, 1);
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}
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else
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{
send_ping(c);
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}
}
else
{
if(debug_lvl >= DEBUG_CONNECTIONS)
syslog(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
c->name, c->hostname);
terminate_connection(c, 0);
}
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}
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}
cp
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}
/*
check all connections to see if anything
happened on their sockets
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*/
void check_network_activity(fd_set *f)
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{
connection_t *c;
avl_node_t *node;
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int result, i;
int len = sizeof(result);
vpn_packet_t packet;
cp
if(FD_ISSET(device_fd, f))
{
if(!read_packet(&packet))
route_outgoing(&packet);
}
for(node = connection_tree->head; node; node = node->next)
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{
c = (connection_t *)node->data;
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if(c->status.remove)
continue;
if(FD_ISSET(c->socket, f))
{
if(c->status.connecting)
{
c->status.connecting = 0;
getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
if(!result)
finish_connecting(c);
else
{
if(debug_lvl >= DEBUG_CONNECTIONS)
syslog(LOG_DEBUG, _("Error while connecting to %s (%s): %s"), c->name, c->hostname, strerror(result));
close(c->socket);
do_outgoing_connection(c);
continue;
}
}
if(receive_meta(c) < 0)
{
terminate_connection(c, c->status.active);
continue;
}
}
}
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for(i = 0; i < listen_sockets; i++)
{
if(FD_ISSET(listen_socket[i].udp, f))
handle_incoming_vpn_data(listen_socket[i].udp);
if(FD_ISSET(listen_socket[i].tcp, f))
handle_new_meta_connection(listen_socket[i].tcp);
}
cp
}
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/*
this is where it all happens...
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*/
void main_loop(void)
{
fd_set fset;
struct timeval tv;
int r;
time_t last_ping_check;
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event_t *event;
cp
last_ping_check = now;
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srand(now);
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for(;;)
{
now = time(NULL);
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tv.tv_sec = 1 + (rand() & 7); /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
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tv.tv_usec = 0;
build_fdset(&fset);
if((r = select(FD_SETSIZE, &fset, NULL, NULL, &tv)) < 0)
{
if(errno != EINTR && errno != EAGAIN)
{
syslog(LOG_ERR, _("Error while waiting for input: %s"), strerror(errno));
cp_trace();
dump_connections();
return;
}
continue;
}
check_network_activity(&fset);
if(do_purge)
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{
purge();
do_purge = 0;
}
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/* Let's check if everybody is still alive */
if(last_ping_check + pingtimeout < now)
{
check_dead_connections();
last_ping_check = now;
if(routing_mode== RMODE_SWITCH)
age_mac();
age_past_requests();
/* Should we regenerate our key? */
if(keyexpires < now)
{
if(debug_lvl >= DEBUG_STATUS)
syslog(LOG_INFO, _("Regenerating symmetric key"));
RAND_pseudo_bytes(myself->key, myself->keylength);
send_key_changed(broadcast, myself);
keyexpires = now + keylifetime;
}
}
while((event = get_expired_event()))
{
event->handler(event->data);
free(event);
}
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if(sigalrm)
{
syslog(LOG_INFO, _("Flushing event queue"));
while(event_tree->head)
{
event = (event_t *)event_tree->head->data;
event->handler(event->data);
event_del(event);
}
sigalrm = 0;
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}
if(sighup)
{
sighup = 0;
close_network_connections();
exit_configuration(&config_tree);
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syslog(LOG_INFO, _("Rereading configuration file and restarting in 5 seconds..."));
sleep(5);
init_configuration(&config_tree);
if(read_server_config())
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{
syslog(LOG_ERR, _("Unable to reread configuration file, exitting."));
exit(1);
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}
if(setup_network_connections())
return;
continue;
}
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}
cp
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}