tinc/src/net.c

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/*
net.c -- most of the network code
Copyright (C) 1998-2005 Ivo Timmermans,
2000-2009 Guus Sliepen <guus@tinc-vpn.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.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
#include "system.h"
#include <openssl/rand.h>
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#include "utils.h"
#include "avl_tree.h"
#include "conf.h"
#include "connection.h"
#include "device.h"
#include "event.h"
#include "graph.h"
#include "logger.h"
#include "meta.h"
#include "net.h"
#include "netutl.h"
#include "process.h"
#include "protocol.h"
#include "route.h"
#include "subnet.h"
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#include "xalloc.h"
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bool do_purge = false;
volatile bool running = false;
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time_t now = 0;
/* Purge edges and subnets of unreachable nodes. Use carefully. */
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static void purge(void)
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{
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avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
node_t *n;
edge_t *e;
subnet_t *s;
cp();
ifdebug(PROTOCOL) logger(LOG_DEBUG, _("Purging unreachable nodes"));
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/* Remove all edges and subnets owned by unreachable nodes. */
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for(nnode = node_tree->head; nnode; nnode = nnext) {
nnext = nnode->next;
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n = nnode->data;
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if(!n->status.reachable) {
ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Purging node %s (%s)"), n->name,
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n->hostname);
for(snode = n->subnet_tree->head; snode; snode = snext) {
snext = snode->next;
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s = snode->data;
if(!tunnelserver)
send_del_subnet(broadcast, s);
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subnet_del(n, s);
}
for(enode = n->edge_tree->head; enode; enode = enext) {
enext = enode->next;
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e = enode->data;
if(!tunnelserver)
send_del_edge(broadcast, e);
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edge_del(e);
}
}
}
/* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
for(nnode = node_tree->head; nnode; nnode = nnext) {
nnext = nnode->next;
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n = nnode->data;
if(!n->status.reachable) {
for(enode = edge_weight_tree->head; enode; enode = enext) {
enext = enode->next;
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e = enode->data;
if(e->to == n)
break;
}
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if(!enode)
node_del(n);
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}
}
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}
/*
put all file descriptors in an fd_set array
While we're at it, purge stuff that needs to be removed.
*/
static int build_fdset(fd_set *readset, fd_set *writeset)
{
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avl_node_t *node, *next;
connection_t *c;
int i, max = 0;
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cp();
FD_ZERO(readset);
FD_ZERO(writeset);
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for(node = connection_tree->head; node; node = next) {
next = node->next;
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c = node->data;
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if(c->status.remove) {
connection_del(c);
if(!connection_tree->head)
purge();
} else {
FD_SET(c->socket, readset);
if(c->outbuflen > 0)
FD_SET(c->socket, writeset);
if(c->socket > max)
max = c->socket;
}
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}
for(i = 0; i < listen_sockets; i++) {
FD_SET(listen_socket[i].tcp, readset);
if(listen_socket[i].tcp > max)
max = listen_socket[i].tcp;
FD_SET(listen_socket[i].udp, readset);
if(listen_socket[i].udp > max)
max = listen_socket[i].udp;
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}
if(device_fd >= 0)
FD_SET(device_fd, readset);
if(device_fd > max)
max = device_fd;
return max;
}
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/*
Terminate a connection:
- Close the socket
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- Remove associated edge and tell other connections about it if report = true
- Check if we need to retry making an outgoing connection
- Deactivate the host
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*/
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void terminate_connection(connection_t *c, bool report)
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{
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cp();
if(c->status.remove)
return;
ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
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c->name, c->hostname);
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c->status.remove = true;
c->status.active = false;
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if(c->node)
c->node->connection = NULL;
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if(c->socket)
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closesocket(c->socket);
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if(c->edge) {
if(report && !tunnelserver)
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send_del_edge(broadcast, c->edge);
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edge_del(c->edge);
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/* Run MST and SSSP algorithms */
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graph();
/* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
if(report && !c->node->status.reachable) {
edge_t *e;
e = lookup_edge(c->node, myself);
if(e) {
if(!tunnelserver)
send_del_edge(broadcast, e);
edge_del(e);
}
}
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}
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/* Check if this was our outgoing connection */
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if(c->outgoing) {
retry_outgoing(c->outgoing);
c->outgoing = NULL;
}
free(c->outbuf);
c->outbuf = NULL;
c->outbuflen = 0;
c->outbufsize = 0;
c->outbufstart = 0;
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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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*/
static void check_dead_connections(void)
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{
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avl_node_t *node, *next;
connection_t *c;
cp();
for(node = connection_tree->head; node; node = next) {
next = node->next;
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c = node->data;
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if(c->last_ping_time + pingtimeout < now) {
if(c->status.active) {
if(c->status.pinged) {
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ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING in %ld seconds"),
c->name, c->hostname, now - c->last_ping_time);
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c->status.timeout = true;
terminate_connection(c, true);
} else if(c->last_ping_time + pinginterval < now) {
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send_ping(c);
}
} else {
if(c->status.remove) {
logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
c->name, c->hostname, bitfield_to_int(&c->status, sizeof c->status));
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connection_del(c);
continue;
}
ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
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c->name, c->hostname);
if(c->status.connecting) {
c->status.connecting = false;
closesocket(c->socket);
do_outgoing_connection(c);
} else {
terminate_connection(c, false);
}
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}
}
if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout < now) {
if(c->status.active) {
ifdebug(CONNECTIONS) logger(LOG_INFO,
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_("%s (%s) could not flush for %ld seconds (%d bytes remaining)"),
c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
c->status.timeout = true;
terminate_connection(c, true);
}
}
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}
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}
/*
check all connections to see if anything
happened on their sockets
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*/
static void check_network_activity(fd_set * readset, fd_set * writeset)
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{
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connection_t *c;
avl_node_t *node;
int result, i;
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socklen_t len = sizeof(result);
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vpn_packet_t packet;
cp();
/* check input from kernel */
if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
if(read_packet(&packet)) {
packet.priority = 0;
route(myself, &packet);
}
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}
/* check meta connections */
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for(node = connection_tree->head; node; node = node->next) {
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c = node->data;
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if(c->status.remove)
continue;
if(FD_ISSET(c->socket, readset)) {
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if(c->status.connecting) {
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c->status.connecting = false;
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getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
if(!result)
finish_connecting(c);
else {
ifdebug(CONNECTIONS) logger(LOG_DEBUG,
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_("Error while connecting to %s (%s): %s"),
c->name, c->hostname, strerror(result));
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closesocket(c->socket);
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do_outgoing_connection(c);
continue;
}
}
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if(!receive_meta(c)) {
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terminate_connection(c, c->status.active);
continue;
}
}
if(FD_ISSET(c->socket, writeset)) {
if(!flush_meta(c)) {
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, readset))
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handle_incoming_vpn_data(listen_socket[i].udp);
if(FD_ISSET(listen_socket[i].tcp, readset))
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handle_new_meta_connection(listen_socket[i].tcp);
}
}
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/*
this is where it all happens...
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*/
int main_loop(void)
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{
fd_set readset, writeset;
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struct timeval tv;
int r, maxfd;
time_t last_ping_check, last_config_check, last_graph_dump;
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event_t *event;
cp();
last_ping_check = now;
last_config_check = now;
last_graph_dump = now;
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srand(now);
running = true;
while(running) {
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now = time(NULL);
// tv.tv_sec = 1 + (rand() & 7); /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
tv.tv_sec = 1;
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tv.tv_usec = 0;
maxfd = build_fdset(&readset, &writeset);
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#ifdef HAVE_MINGW
LeaveCriticalSection(&mutex);
#endif
r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
#ifdef HAVE_MINGW
EnterCriticalSection(&mutex);
#endif
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if(r < 0) {
if(errno != EINTR && errno != EAGAIN) {
logger(LOG_ERR, _("Error while waiting for input: %s"),
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strerror(errno));
cp_trace();
dump_connections();
return 1;
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}
continue;
}
check_network_activity(&readset, &writeset);
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if(do_purge) {
purge();
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do_purge = false;
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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_subnets();
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age_past_requests();
/* Should we regenerate our key? */
if(keyexpires < now) {
avl_node_t *node;
node_t *n;
ifdebug(STATUS) logger(LOG_INFO, _("Expiring symmetric keys"));
for(node = node_tree->head; node; node = node->next) {
n = node->data;
if(n->inkey) {
free(n->inkey);
n->inkey = NULL;
}
}
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send_key_changed(broadcast, myself);
keyexpires = now + keylifetime;
}
}
if(sigalrm) {
logger(LOG_INFO, _("Flushing event queue"));
expire_events();
sigalrm = false;
}
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while((event = get_expired_event())) {
event->handler(event->data);
free_event(event);
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}
if(sighup) {
connection_t *c;
avl_node_t *node;
char *fname;
struct stat s;
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sighup = false;
/* Reread our own configuration file */
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exit_configuration(&config_tree);
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init_configuration(&config_tree);
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if(!read_server_config()) {
logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
return 1;
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}
/* Close connections to hosts that have a changed or deleted host config file */
for(node = connection_tree->head; node; node = node->next) {
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c = node->data;
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xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
if(stat(fname, &s) || s.st_mtime > last_config_check)
terminate_connection(c, c->status.active);
free(fname);
}
last_config_check = now;
/* Try to make outgoing connections */
try_outgoing_connections();
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}
/* Dump graph if wanted every 60 seconds*/
if(last_graph_dump + 60 < now) {
dump_graph();
last_graph_dump = now;
}
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}
return 0;
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}