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- /*
- net.c -- most of the network code
- Copyright (C) 1998-2005 Ivo Timmermans,
- 2000-2015 Guus Sliepen <guus@tinc-vpn.org>
- 2006 Scott Lamb <slamb@slamb.org>
- 2011 Loïc Grenié <loic.grenie@gmail.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.,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
- #include "system.h"
- #include <openssl/rand.h>
- #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"
- #include "xalloc.h"
- bool do_purge = false;
- volatile bool running = false;
- #ifdef HAVE_PSELECT
- bool graph_dump = false;
- #endif
- time_t now = 0;
- int contradicting_add_edge = 0;
- int contradicting_del_edge = 0;
- static int sleeptime = 10;
- /* Purge edges and subnets of unreachable nodes. Use carefully. */
- static void purge(void) {
- avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
- node_t *n;
- edge_t *e;
- subnet_t *s;
- ifdebug(PROTOCOL) logger(LOG_DEBUG, "Purging unreachable nodes");
- /* Remove all edges and subnets owned by unreachable nodes. */
- for(nnode = node_tree->head; nnode; nnode = nnext) {
- nnext = nnode->next;
- n = nnode->data;
- if(!n->status.reachable) {
- ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Purging node %s (%s)", n->name,
- n->hostname);
- for(snode = n->subnet_tree->head; snode; snode = snext) {
- snext = snode->next;
- s = snode->data;
- send_del_subnet(everyone, s);
- if(!strictsubnets) {
- subnet_del(n, s);
- }
- }
- for(enode = n->edge_tree->head; enode; enode = enext) {
- enext = enode->next;
- e = enode->data;
- if(!tunnelserver) {
- send_del_edge(everyone, e);
- }
- 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;
- n = nnode->data;
- if(!n->status.reachable) {
- for(enode = edge_weight_tree->head; enode; enode = enext) {
- enext = enode->next;
- e = enode->data;
- if(e->to == n) {
- break;
- }
- }
- if(!enode && (!strictsubnets || !n->subnet_tree->head))
- /* in strictsubnets mode do not delete nodes with subnets */
- {
- node_del(n);
- }
- }
- }
- }
- /*
- 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) {
- avl_node_t *node, *next;
- connection_t *c;
- int i, max = 0;
- FD_ZERO(readset);
- FD_ZERO(writeset);
- for(node = connection_tree->head; node; node = next) {
- next = node->next;
- c = node->data;
- if(c->status.remove) {
- connection_del(c);
- if(!connection_tree->head) {
- purge();
- }
- } else {
- FD_SET(c->socket, readset);
- if(c->outbuflen > 0 || c->status.connecting) {
- FD_SET(c->socket, writeset);
- }
- if(c->socket > max) {
- max = c->socket;
- }
- }
- }
- 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;
- }
- }
- if(device_fd >= 0) {
- FD_SET(device_fd, readset);
- }
- if(device_fd > max) {
- max = device_fd;
- }
- return max;
- }
- /* Put a misbehaving connection in the tarpit */
- void tarpit(int fd) {
- static int pits[10] = {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1};
- static int next_pit = 0;
- if(pits[next_pit] != -1) {
- closesocket(pits[next_pit]);
- }
- pits[next_pit++] = fd;
- if(next_pit >= (int)(sizeof pits / sizeof pits[0])) {
- next_pit = 0;
- }
- }
- /*
- Terminate a connection:
- - Close the socket
- - 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
- */
- void terminate_connection(connection_t *c, bool report) {
- if(c->status.remove) {
- return;
- }
- ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Closing connection with %s (%s)",
- c->name, c->hostname);
- c->status.remove = true;
- c->status.active = false;
- if(c->node) {
- c->node->connection = NULL;
- }
- if(c->socket) {
- if(c->status.tarpit) {
- tarpit(c->socket);
- } else {
- closesocket(c->socket);
- }
- }
- if(c->edge) {
- if(!c->node) {
- logger(LOG_ERR, "Connection to %s (%s) has an edge but node is NULL!", c->name, c->hostname);
- // And that should never happen.
- abort();
- }
- if(report && !tunnelserver) {
- send_del_edge(everyone, c->edge);
- }
- edge_del(c->edge);
- c->edge = NULL;
- /* Run MST and SSSP algorithms */
- 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(everyone, e);
- }
- edge_del(e);
- }
- }
- }
- free_connection_partially(c);
- /* Check if this was our outgoing connection */
- if(c->outgoing) {
- c->status.remove = false;
- do_outgoing_connection(c);
- }
- #ifndef HAVE_MINGW
- /* Clean up dead proxy processes */
- while(waitpid(-1, NULL, WNOHANG) > 0);
- #endif
- }
- /*
- 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.
- */
- static void check_dead_connections(void) {
- avl_node_t *node, *next;
- connection_t *c;
- for(node = connection_tree->head; node; node = next) {
- next = node->next;
- c = node->data;
- if(c->last_ping_time + pingtimeout <= now) {
- if(c->status.active) {
- if(c->status.pinged) {
- ifdebug(CONNECTIONS) logger(LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds",
- c->name, c->hostname, (long)(now - c->last_ping_time));
- c->status.timeout = true;
- terminate_connection(c, true);
- } else if(c->last_ping_time + pinginterval <= now) {
- 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)));
- connection_del(c);
- continue;
- }
- ifdebug(CONNECTIONS) logger(LOG_WARNING, "Timeout from %s (%s) during authentication",
- c->name, c->hostname);
- if(c->status.connecting) {
- c->status.connecting = false;
- closesocket(c->socket);
- do_outgoing_connection(c);
- } else {
- c->status.tarpit = true;
- terminate_connection(c, false);
- }
- }
- }
- if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout <= now) {
- if(c->status.active) {
- ifdebug(CONNECTIONS) logger(LOG_INFO,
- "%s (%s) could not flush for %ld seconds (%d bytes remaining)",
- c->name, c->hostname, (long)(now - c->last_flushed_time), c->outbuflen);
- c->status.timeout = true;
- terminate_connection(c, true);
- }
- }
- }
- }
- /*
- check all connections to see if anything
- happened on their sockets
- */
- static void check_network_activity(fd_set *readset, fd_set *writeset) {
- connection_t *c;
- avl_node_t *node;
- int result, i;
- socklen_t len = sizeof(result);
- vpn_packet_t packet;
- static int errors = 0;
- /* check input from kernel */
- if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
- if(devops.read(&packet)) {
- if(packet.len) {
- errors = 0;
- packet.priority = 0;
- route(myself, &packet);
- }
- } else {
- usleep(errors * 50000);
- errors++;
- if(errors > 10) {
- logger(LOG_ERR, "Too many errors from %s, exiting!", device);
- running = false;
- }
- }
- }
- /* check meta connections */
- for(node = connection_tree->head; node; node = node->next) {
- c = node->data;
- if(c->status.remove) {
- continue;
- }
- if(FD_ISSET(c->socket, writeset)) {
- if(c->status.connecting) {
- c->status.connecting = false;
- getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
- if(!result) {
- finish_connecting(c);
- } else {
- ifdebug(CONNECTIONS) logger(LOG_DEBUG,
- "Error while connecting to %s (%s): %s",
- c->name, c->hostname, sockstrerror(result));
- closesocket(c->socket);
- do_outgoing_connection(c);
- continue;
- }
- }
- if(!flush_meta(c)) {
- terminate_connection(c, c->status.active);
- continue;
- }
- }
- if(FD_ISSET(c->socket, readset)) {
- if(!receive_meta(c)) {
- c->status.tarpit = true;
- terminate_connection(c, c->status.active);
- continue;
- }
- }
- }
- for(i = 0; i < listen_sockets; i++) {
- if(FD_ISSET(listen_socket[i].udp, readset)) {
- handle_incoming_vpn_data(i);
- }
- if(FD_ISSET(listen_socket[i].tcp, readset)) {
- handle_new_meta_connection(listen_socket[i].tcp);
- }
- }
- }
- /*
- this is where it all happens...
- */
- int main_loop(void) {
- fd_set readset, writeset;
- #ifdef HAVE_PSELECT
- struct timespec tv;
- sigset_t omask, block_mask;
- time_t next_event;
- #else
- struct timeval tv;
- #endif
- int r, maxfd;
- time_t last_ping_check, last_config_check, last_graph_dump;
- event_t *event;
- last_ping_check = now;
- last_config_check = now;
- last_graph_dump = now;
- srand(now);
- #ifdef HAVE_PSELECT
- if(lookup_config(config_tree, "GraphDumpFile")) {
- graph_dump = true;
- }
- /* Block SIGHUP & SIGALRM */
- sigemptyset(&block_mask);
- sigaddset(&block_mask, SIGHUP);
- sigaddset(&block_mask, SIGALRM);
- sigprocmask(SIG_BLOCK, &block_mask, &omask);
- #endif
- running = true;
- while(running) {
- #ifdef HAVE_PSELECT
- next_event = last_ping_check + pingtimeout;
- if(graph_dump && next_event > last_graph_dump + 60) {
- next_event = last_graph_dump + 60;
- }
- if((event = peek_next_event()) && next_event > event->time) {
- next_event = event->time;
- }
- if(next_event <= now) {
- tv.tv_sec = 0;
- } else {
- tv.tv_sec = next_event - now;
- }
- tv.tv_nsec = 0;
- #else
- tv.tv_sec = 1;
- tv.tv_usec = 0;
- #endif
- maxfd = build_fdset(&readset, &writeset);
- #ifdef HAVE_MINGW
- LeaveCriticalSection(&mutex);
- #endif
- #ifdef HAVE_PSELECT
- r = pselect(maxfd + 1, &readset, &writeset, NULL, &tv, &omask);
- #else
- r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
- #endif
- now = time(NULL);
- #ifdef HAVE_MINGW
- EnterCriticalSection(&mutex);
- #endif
- if(r < 0) {
- if(!sockwouldblock(sockerrno)) {
- logger(LOG_ERR, "Error while waiting for input: %s", sockstrerror(sockerrno));
- dump_connections();
- return 1;
- }
- }
- if(r > 0) {
- check_network_activity(&readset, &writeset);
- }
- if(do_purge) {
- purge();
- do_purge = false;
- }
- /* 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();
- }
- 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;
- }
- }
- send_key_changed();
- keyexpires = now + keylifetime;
- }
- /* Detect ADD_EDGE/DEL_EDGE storms that are caused when
- * two tinc daemons with the same name are on the VPN.
- * If so, sleep a while. If this happens multiple times
- * in a row, sleep longer. */
- if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
- logger(LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
- usleep(sleeptime * 1000000LL);
- sleeptime *= 2;
- if(sleeptime < 0) {
- sleeptime = 3600;
- }
- } else {
- sleeptime /= 2;
- if(sleeptime < 10) {
- sleeptime = 10;
- }
- }
- contradicting_add_edge = 0;
- contradicting_del_edge = 0;
- }
- if(sigalrm) {
- avl_node_t *node;
- logger(LOG_INFO, "Flushing event queue");
- expire_events();
- for(node = connection_tree->head; node; node = node->next) {
- connection_t *c = node->data;
- if(c->status.active) {
- send_ping(c);
- }
- }
- sigalrm = false;
- }
- while((event = get_expired_event())) {
- event->handler(event->data);
- free_event(event);
- }
- if(sighup) {
- connection_t *c;
- avl_node_t *node, *next;
- char *fname;
- struct stat s;
- sighup = false;
- reopenlogger();
- /* Reread our own configuration file */
- exit_configuration(&config_tree);
- init_configuration(&config_tree);
- if(!read_server_config()) {
- logger(LOG_ERR, "Unable to reread configuration file, exitting.");
- return 1;
- }
- /* Cancel non-active outgoing connections */
- for(node = connection_tree->head; node; node = next) {
- next = node->next;
- c = node->data;
- c->outgoing = NULL;
- if(c->status.connecting) {
- terminate_connection(c, false);
- connection_del(c);
- }
- }
- /* Wipe list of outgoing connections */
- for(list_node_t *node = outgoing_list->head; node; node = node->next) {
- outgoing_t *outgoing = node->data;
- if(outgoing->event) {
- event_del(outgoing->event);
- }
- }
- list_delete_list(outgoing_list);
- /* Close connections to hosts that have a changed or deleted host config file */
- for(node = connection_tree->head; node; node = node->next) {
- c = node->data;
- 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;
- /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
- if(strictsubnets) {
- subnet_t *subnet;
- for(node = subnet_tree->head; node; node = node->next) {
- subnet = node->data;
- subnet->expires = 1;
- }
- load_all_subnets();
- for(node = subnet_tree->head; node; node = next) {
- next = node->next;
- subnet = node->data;
- if(subnet->expires == 1) {
- send_del_subnet(everyone, subnet);
- if(subnet->owner->status.reachable) {
- subnet_update(subnet->owner, subnet, false);
- }
- subnet_del(subnet->owner, subnet);
- } else if(subnet->expires == -1) {
- subnet->expires = 0;
- } else {
- send_add_subnet(everyone, subnet);
- if(subnet->owner->status.reachable) {
- subnet_update(subnet->owner, subnet, true);
- }
- }
- }
- }
- /* Try to make outgoing connections */
- try_outgoing_connections();
- }
- /* Dump graph if wanted every 60 seconds*/
- if(last_graph_dump + 60 <= now) {
- dump_graph();
- last_graph_dump = now;
- }
- }
- #ifdef HAVE_PSELECT
- /* Restore SIGHUP & SIGALARM mask */
- sigprocmask(SIG_SETMASK, &omask, NULL);
- #endif
- return 0;
- }
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