If a net_crypto connection isn't using the TCP relays, disconnect from them.

TCP_connections can now be put to sleep, a state where they store what they
were connected to without being connected and then resumed from sleep.

toxcore/TCP_connection.c

@@ -333,6 +333,9 @@ int tcp_send_oob_packet(TCP_Connections *tcp_c, unsigned int tcp_connections_num
     if (!tcp_con)
         return -1;
 
+    if (tcp_con->status != TCP_CONN_CONNECTED)
+        return -1;
+
     int ret = send_oob_packet(tcp_con->connection, public_key, packet, length);
 
     if (ret == 1)
@@ -404,11 +407,17 @@ static int find_tcp_connection_relay(TCP_Connections *tcp_c, const uint8_t *rela
         TCP_con *tcp_con = get_tcp_connection(tcp_c, i);
 
         if (tcp_con) {
+            if (tcp_con->status == TCP_CONN_SLEEPING) {
+                if (memcmp(tcp_con->relay_pk, relay_pk, crypto_box_PUBLICKEYBYTES) == 0) {
+                    return i;
+                }
+            } else {
                 if (memcmp(tcp_con->connection->public_key, relay_pk, crypto_box_PUBLICKEYBYTES) == 0) {
                     return i;
                 }
             }
         }
+    }
 
     return -1;
 }
@@ -465,6 +474,10 @@ int kill_tcp_connection_to(TCP_Connections *tcp_c, int connections_number)
 
             if (con_to->connections[i].status == TCP_CONNECTIONS_STATUS_ONLINE) {
                 --tcp_con->lock_count;
+
+                if (con_to->status == TCP_CONN_SLEEPING) {
+                    --tcp_con->sleep_count;
+                }
             }
         }
     }
@@ -472,6 +485,72 @@ int kill_tcp_connection_to(TCP_Connections *tcp_c, int connections_number)
     return wipe_connection(tcp_c, connections_number);
 }
 
+/* Set connection status.
+ *
+ * status of 1 means we are using the connection.
+ * status of 0 means we are not using it.
+ *
+ * Unused tcp connections will be disconnected from but kept in case they are needed.
+ *
+ * return 0 on success.
+ * return -1 on failure.
+ */
+int set_tcp_connection_to_status(TCP_Connections *tcp_c, int connections_number, _Bool status)
+{
+    TCP_Connection_to *con_to = get_connection(tcp_c, connections_number);
+
+    if (!con_to)
+        return -1;
+
+    if (status) {
+        /* Conection is unsleeping. */
+        if (con_to->status != TCP_CONN_SLEEPING)
+            return -1;
+
+        unsigned int i;
+
+        for (i = 0; i < MAX_FRIEND_TCP_CONNECTIONS; ++i) {
+            if (con_to->connections[i].tcp_connection) {
+                unsigned int tcp_connections_number = con_to->connections[i].tcp_connection - 1;
+                TCP_con *tcp_con = get_tcp_connection(tcp_c, tcp_connections_number);
+
+                if (!tcp_con)
+                    continue;
+
+                if (tcp_con->status == TCP_CONN_SLEEPING) {
+                    tcp_con->unsleep = 1;
+                }
+            }
+        }
+
+        con_to->status = TCP_CONN_VALID;
+        return 0;
+    } else {
+        /* Conection is going to sleep. */
+        if (con_to->status != TCP_CONN_VALID)
+            return -1;
+
+        unsigned int i;
+
+        for (i = 0; i < MAX_FRIEND_TCP_CONNECTIONS; ++i) {
+            if (con_to->connections[i].tcp_connection) {
+                unsigned int tcp_connections_number = con_to->connections[i].tcp_connection - 1;
+                TCP_con *tcp_con = get_tcp_connection(tcp_c, tcp_connections_number);
+
+                if (!tcp_con)
+                    continue;
+
+                if (con_to->connections[i].status == TCP_CONNECTIONS_STATUS_ONLINE) {
+                    ++tcp_con->sleep_count;
+                }
+            }
+        }
+
+        con_to->status = TCP_CONN_SLEEPING;
+        return 0;
+    }
+}
+
 static _Bool tcp_connection_in_conn(TCP_Connection_to *con_to, int tcp_connections_number)
 {
     unsigned int i;
@@ -606,6 +685,9 @@ static int reconnect_tcp_relay_connection(TCP_Connections *tcp_c, int tcp_connec
     if (!tcp_con)
         return -1;
 
+    if (tcp_con->status == TCP_CONN_SLEEPING)
+        return -1;
+
     IP_Port ip_port = tcp_con->connection->ip_port;
     uint8_t relay_pk[crypto_box_PUBLICKEYBYTES];
     memcpy(relay_pk, tcp_con->connection->public_key, crypto_box_PUBLICKEYBYTES);
@@ -634,12 +716,83 @@ static int reconnect_tcp_relay_connection(TCP_Connections *tcp_c, int tcp_connec
     }
 
     tcp_con->lock_count = 0;
+    tcp_con->sleep_count = 0;
     tcp_con->connected_time = 0;
     tcp_con->status = TCP_CONN_VALID;
+    tcp_con->unsleep = 0;
 
     return 0;
 }
 
+static int sleep_tcp_relay_connection(TCP_Connections *tcp_c, int tcp_connections_number)
+{
+    TCP_con *tcp_con = get_tcp_connection(tcp_c, tcp_connections_number);
+
+    if (!tcp_con)
+        return -1;
+
+    if (tcp_con->status != TCP_CONN_CONNECTED)
+        return -1;
+
+    if (tcp_con->lock_count != tcp_con->sleep_count)
+        return -1;
+
+    tcp_con->ip_port = tcp_con->connection->ip_port;
+    memcpy(tcp_con->relay_pk, tcp_con->connection->public_key, crypto_box_PUBLICKEYBYTES);
+
+    kill_TCP_connection(tcp_con->connection);
+    tcp_con->connection = NULL;
+
+    unsigned int i;
+
+    for (i = 0; i < tcp_c->connections_length; ++i) {
+        TCP_Connection_to *con_to = get_connection(tcp_c, i);
+
+        if (con_to) {
+            set_tcp_connection_status(con_to, tcp_connections_number, TCP_CONNECTIONS_STATUS_NONE, 0);
+        }
+    }
+
+    if (tcp_con->onion) {
+        --tcp_c->onion_num_conns;
+        tcp_con->onion = 0;
+    }
+
+    tcp_con->lock_count = 0;
+    tcp_con->sleep_count = 0;
+    tcp_con->connected_time = 0;
+    tcp_con->status = TCP_CONN_SLEEPING;
+    tcp_con->unsleep = 0;
+
+    return 0;
+}
+
+static int unsleep_tcp_relay_connection(TCP_Connections *tcp_c, int tcp_connections_number)
+{
+    TCP_con *tcp_con = get_tcp_connection(tcp_c, tcp_connections_number);
+
+    if (!tcp_con)
+        return -1;
+
+    if (tcp_con->status != TCP_CONN_SLEEPING)
+        return -1;
+
+    tcp_con->connection = new_TCP_connection(tcp_con->ip_port, tcp_con->relay_pk, tcp_c->dht->self_public_key,
+                          tcp_c->dht->self_secret_key, &tcp_c->proxy_info);
+
+    if (!tcp_con->connection) {
+        kill_tcp_relay_connection(tcp_c, tcp_connections_number);
+        return -1;
+    }
+
+    tcp_con->lock_count = 0;
+    tcp_con->sleep_count = 0;
+    tcp_con->connected_time = 0;
+    tcp_con->status = TCP_CONN_VALID;
+    tcp_con->unsleep = 0;
+    return 0;
+}
+
 /* Send a TCP routing request.
  *
  * return 0 on success.
@@ -652,6 +805,9 @@ static int send_tcp_relay_routing_request(TCP_Connections *tcp_c, int tcp_connec
     if (!tcp_con)
         return -1;
 
+    if (tcp_con->status == TCP_CONN_SLEEPING)
+        return -1;
+
     if (send_routing_request(tcp_con->connection, public_key) != 1)
         return -1;
 
@@ -704,11 +860,19 @@ static int tcp_status_callback(void *object, uint32_t number, uint8_t connection
             return -1;
 
         --tcp_con->lock_count;
+
+        if (con_to->status == TCP_CONN_SLEEPING) {
+            --tcp_con->sleep_count;
+        }
     } else if (status == 2) {
         if (set_tcp_connection_status(con_to, tcp_connections_number, TCP_CONNECTIONS_STATUS_ONLINE, connection_id) == -1)
             return -1;
 
         ++tcp_con->lock_count;
+
+        if (con_to->status == TCP_CONN_SLEEPING) {
+            ++tcp_con->sleep_count;
+        }
     }
 
     return 0;
@@ -906,6 +1070,10 @@ int add_tcp_number_relay_connection(TCP_Connections *tcp_c, int connections_numb
     if (!tcp_con)
         return -1;
 
+    if (con_to->status != TCP_CONN_SLEEPING && tcp_con->status == TCP_CONN_SLEEPING) {
+        tcp_con->unsleep = 1;
+    }
+
     if (add_tcp_connection_to_conn(con_to, tcp_connections_number) == -1)
         return -1;
 
@@ -1012,6 +1180,7 @@ static void do_tcp_conns(TCP_Connections *tcp_c)
         TCP_con *tcp_con = get_tcp_connection(tcp_c, i);
 
         if (tcp_con) {
+            if (tcp_con->status != TCP_CONN_SLEEPING) {
                 do_TCP_connection(tcp_con->connection);
 
                 /* callbacks can change TCP connection address. */
@@ -1030,6 +1199,17 @@ static void do_tcp_conns(TCP_Connections *tcp_c)
                 if (tcp_con->status == TCP_CONN_VALID && tcp_con->connection->status == TCP_CLIENT_CONFIRMED) {
                     tcp_relay_on_online(tcp_c, i);
                 }
+
+                if (tcp_con->status == TCP_CONN_CONNECTED && !tcp_con->onion && tcp_con->lock_count
+                        && tcp_con->lock_count == tcp_con->sleep_count
+                        && is_timeout(tcp_con->connected_time, TCP_CONNECTION_ANNOUNCE_TIMEOUT)) {
+                    sleep_tcp_relay_connection(tcp_c, i);
+                }
+            }
+
+            if (tcp_con->status == TCP_CONN_SLEEPING && tcp_con->unsleep) {
+                unsleep_tcp_relay_connection(tcp_c, i);
+            }
         }
     }
 }

toxcore/TCP_connection.h

@@ -28,8 +28,13 @@
 
 #define TCP_CONN_NONE 0
 #define TCP_CONN_VALID 1
+
+/* NOTE: only used by TCP_con */
 #define TCP_CONN_CONNECTED 2
 
+/* Connection is not connected but can be quickly reconnected in case it is needed. */
+#define TCP_CONN_SLEEPING 3
+
 #define TCP_CONNECTIONS_STATUS_NONE 0
 #define TCP_CONNECTIONS_STATUS_REGISTERED 1
 #define TCP_CONNECTIONS_STATUS_ONLINE 2
@@ -64,7 +69,13 @@ typedef struct {
     TCP_Client_Connection *connection;
     uint64_t connected_time;
     uint32_t lock_count;
+    uint32_t sleep_count;
     _Bool onion;
+
+    /* Only used when connection is sleeping. */
+    IP_Port ip_port;
+    uint8_t relay_pk[crypto_box_PUBLICKEYBYTES];
+    _Bool unsleep; /* set to 1 to unsleep connection. */
 } TCP_con;
 
 typedef struct {
@@ -153,6 +164,18 @@ int new_tcp_connection_to(TCP_Connections *tcp_c, const uint8_t *public_key, int
  */
 int kill_tcp_connection_to(TCP_Connections *tcp_c, int connections_number);
 
+/* Set connection status.
+ *
+ * status of 1 means we are using the connection.
+ * status of 0 means we are not using it.
+ *
+ * Unused tcp connections will be disconnected from but kept in case they are needed.
+ *
+ * return 0 on success.
+ * return -1 on failure.
+ */
+int set_tcp_connection_to_status(TCP_Connections *tcp_c, int connections_number, _Bool status);
+
 /* Add a TCP relay tied to a connection.
  *
  * NOTE: This can only be used during the tcp_oob_callback.

toxcore/net_crypto.c

@@ -1798,6 +1798,30 @@ static void do_tcp(Net_Crypto *c)
     pthread_mutex_lock(&c->tcp_mutex);
     do_tcp_connections(c->tcp_c);
     pthread_mutex_unlock(&c->tcp_mutex);
+
+    uint32_t i;
+
+    for (i = 0; i < c->crypto_connections_length; ++i) {
+        Crypto_Connection *conn = get_crypto_connection(c, i);
+
+        if (conn == 0)
+            return;
+
+        if (conn->status == CRYPTO_CONN_ESTABLISHED) {
+            uint8_t direct_connected = 0;
+            crypto_connection_status(c, i, &direct_connected);
+
+            if (direct_connected) {
+                pthread_mutex_lock(&c->tcp_mutex);
+                set_tcp_connection_to_status(c->tcp_c, conn->connection_number_tcp, 0);
+                pthread_mutex_unlock(&c->tcp_mutex);
+            } else {
+                pthread_mutex_lock(&c->tcp_mutex);
+                set_tcp_connection_to_status(c->tcp_c, conn->connection_number_tcp, 1);
+                pthread_mutex_unlock(&c->tcp_mutex);
+            }
+        }
+    }
 }
 
 /* Set function to be called when connection with crypt_connection_id goes connects/disconnects.