2 autoconnect.c -- automatic connection establishment
3 Copyright (C) 2017 Guus Sliepen <guus@tinc-vpn.org>
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License along
16 with this program; if not, write to the Free Software Foundation, Inc.,
17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22 #include "connection.h"
27 static void make_new_connection() {
28 /* Select a random node we haven't connected to yet. */
30 for splay_each(node_t, n, node_tree) {
31 if(n == myself || n->connection || !(n->status.has_address || n->status.reachable))
39 int r = rand() % count;
41 for splay_each(node_t, n, node_tree) {
42 if(n == myself || n->connection || !(n->status.has_address || n->status.reachable))
50 for list_each(outgoing_t, outgoing, outgoing_list) {
51 if(!strcmp(outgoing->name, n->name)) {
58 logger(DEBUG_CONNECTIONS, LOG_INFO, "Autoconnecting to %s", n->name);
59 outgoing_t *outgoing = xzalloc(sizeof *outgoing);
60 outgoing->name = xstrdup(n->name);
61 list_insert_tail(outgoing_list, outgoing);
62 setup_outgoing_connection(outgoing);
69 static void connect_to_unreachable() {
70 /* Select a random known node. The rationale is that if there are many
71 * reachable nodes, and only a few unreachable nodes, we don't want all
72 * reachable nodes to try to connect to the unreachable ones at the
73 * same time. This way, we back off automatically. Conversely, if there
74 * are only a few reachable nodes, and many unreachable ones, we're
75 * going to try harder to connect to them. */
77 int r = rand() % node_tree->count;
79 for splay_each(node_t, n, node_tree) {
83 /* Is it unreachable and do we know an address for it? If not, return. */
84 if(n == myself || n->connection || n->status.reachable || !n->status.has_address)
87 /* Are we already trying to make an outgoing connection to it? If not, return. */
88 for list_each(outgoing_t, outgoing, outgoing_list)
89 if(!strcmp(outgoing->name, n->name))
92 logger(DEBUG_CONNECTIONS, LOG_INFO, "Autoconnecting to %s", n->name);
93 outgoing_t *outgoing = xzalloc(sizeof *outgoing);
94 outgoing->name = xstrdup(n->name);
95 list_insert_tail(outgoing_list, outgoing);
96 setup_outgoing_connection(outgoing);
102 static void drop_superfluous_outgoing_connection() {
103 /* Choose a random outgoing connection to a node that has at least one other connection. */
105 for list_each(connection_t, c, connection_list) {
106 if(!c->edge || !c->outgoing || !c->node || c->node->edge_tree->count < 2)
114 int r = rand() % count;
116 for list_each(connection_t, c, connection_list) {
117 if(!c->edge || !c->outgoing || !c->node || c->node->edge_tree->count < 2)
123 logger(DEBUG_CONNECTIONS, LOG_INFO, "Autodisconnecting from %s", c->name);
124 list_delete(outgoing_list, c->outgoing);
126 terminate_connection(c, c->edge);
131 static void drop_superfluous_pending_connections() {
132 for list_each(outgoing_t, o, outgoing_list) {
133 /* Only look for connections that are waiting to be retried later. */
135 for list_each(connection_t, c, connection_list) {
136 if(c->outgoing == o) {
145 logger(DEBUG_CONNECTIONS, LOG_INFO, "Cancelled outgoing connection to %s", o->name);
146 list_delete_node(outgoing_list, node);
150 void do_autoconnect() {
151 /* Count number of active connections. */
153 for list_each(connection_t, c, connection_list) {
158 /* Less than 3 connections? Eagerly try to make a new one. */
160 make_new_connection();
164 /* More than 3 connections? See if we can get rid of a superfluous one. */
166 drop_superfluous_outgoing_connection();
169 /* Check if there are unreachable nodes that we should try to connect to. */
170 connect_to_unreachable();
172 /* Drop pending outgoing connections from the outgoing list. */
173 drop_superfluous_pending_connections();