mirror of https://github.com/asterisk/asterisk
Matt Jordan
10 years ago
committed by
Gerrit Code Review
commit
e8f78f87a8
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/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2015, Digium, Inc.
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*
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* Matt Jordan <mjordan@digium.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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*
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* \brief Bridging module for maintaining T.38 state for faxing channels
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*
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* \author Matt Jordan <mjordan@digium.com>
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*
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* \ingroup bridges
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*/
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/*** MODULEINFO
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<support_level>core</support_level>
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***/
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#include "asterisk.h"
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ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
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#include "asterisk/module.h"
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#include "asterisk/channel.h"
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#include "asterisk/bridge.h"
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#include "asterisk/bridge_technology.h"
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#include "asterisk/frame.h"
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/*! \brief The current state of the T.38 fax for the channels in our bridge */
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struct t38_bridge_state {
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/* \brief First channel in the bridge */
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struct ast_bridge_channel *bc0;
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/*! \brief Second channel in the bridge */
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struct ast_bridge_channel *bc1;
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/*! \brief T.38 state of \c bc0 */
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enum ast_t38_state c0_state;
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/*! \brief T.38 state of \c bc1 */
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enum ast_t38_state c1_state;
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};
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static void t38_bridge_destroy(struct ast_bridge *bridge)
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{
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struct t38_bridge_state *state = bridge->tech_pvt;
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ast_free(state);
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bridge->tech_pvt = NULL;
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}
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static int t38_bridge_create(struct ast_bridge *bridge)
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{
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struct t38_bridge_state *state;
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state = ast_calloc(1, sizeof(*state));
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if (!state) {
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return -1;
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}
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bridge->tech_pvt = state;
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return 0;
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}
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static int t38_bridge_start(struct ast_bridge *bridge)
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{
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struct ast_bridge_channel *bc0 = AST_LIST_FIRST(&bridge->channels);
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struct ast_bridge_channel *bc1 = AST_LIST_LAST(&bridge->channels);
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struct t38_bridge_state *state = bridge->tech_pvt;
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state->bc0 = bc0;
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state->bc1 = bc1;
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state->c0_state = ast_channel_get_t38_state(state->bc0->chan);
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state->c1_state = ast_channel_get_t38_state(state->bc1->chan);
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return 0;
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}
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static void send_termination_update(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, enum ast_t38_state chan_state)
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{
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/* Inform the other side that T.38 faxing is done */
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struct ast_control_t38_parameters parameters = { .request_response = 0, };
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if (!bridge_channel) {
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return;
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}
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ast_debug(5, "Bridge %s T.38: Current state of %s is %d\n",
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bridge->uniqueid, ast_channel_name(bridge_channel->chan), chan_state);
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if (chan_state == T38_STATE_NEGOTIATING) {
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parameters.request_response = AST_T38_REFUSED;
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} else if (chan_state == T38_STATE_NEGOTIATED) {
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parameters.request_response = AST_T38_TERMINATED;
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}
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if (parameters.request_response) {
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struct ast_frame f = {
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.frametype = AST_FRAME_CONTROL,
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.subclass.integer = AST_CONTROL_T38_PARAMETERS,
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.data.ptr = ¶meters,
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.datalen = sizeof(parameters),
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};
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/* When sending a termination update to a channel, the bridge is highly
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* likely to be getting torn down. Queueing a frame through the bridging
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* framework won't work, as the frame will likely just get tossed as the
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* bridge collapses. Hence, we write directly to the channel to ensure that
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* they know they aren't in a T.38 fax any longer.
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*/
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ast_debug(3, "Bridge %s T.38: Informing %s to switch to %d\n",
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bridge->uniqueid, ast_channel_name(bridge_channel->chan), parameters.request_response);
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ast_write(bridge_channel->chan, &f);
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}
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}
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static void t38_bridge_stop(struct ast_bridge *bridge)
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{
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struct t38_bridge_state *state = bridge->tech_pvt;
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send_termination_update(bridge, state->bc0, state->c0_state);
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send_termination_update(bridge, state->bc1, state->c1_state);
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}
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static void t38_bridge_leave(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
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{
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struct t38_bridge_state *state = bridge->tech_pvt;
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if (bridge_channel == state->bc0) {
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send_termination_update(bridge, state->bc0, state->c0_state);
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state->bc0 = NULL;
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state->c0_state = T38_STATE_UNKNOWN;
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} else {
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send_termination_update(bridge, state->bc1, state->c1_state);
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state->bc1 = NULL;
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state->c1_state = T38_STATE_UNKNOWN;
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}
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}
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static int t38_bridge_write(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
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{
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struct t38_bridge_state *state = bridge->tech_pvt;
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enum ast_t38_state *c_state;
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enum ast_t38_state *other_state;
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if (!bridge_channel) {
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return -1;
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}
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c_state = bridge_channel == state->bc0 ? &(state->c0_state) : &(state->c1_state);
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other_state = bridge_channel == state->bc0 ? &(state->c1_state) : &(state->c0_state);
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switch (frame->frametype) {
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case AST_FRAME_CONTROL:
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switch (frame->subclass.integer) {
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case AST_CONTROL_T38_PARAMETERS:
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{
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struct ast_control_t38_parameters *parameters = frame->data.ptr;
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switch (parameters->request_response) {
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case AST_T38_REQUEST_NEGOTIATE:
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*c_state = T38_STATE_NEGOTIATING;
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*other_state = T38_STATE_NEGOTIATING;
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break;
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case AST_T38_NEGOTIATED:
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*c_state = T38_STATE_NEGOTIATED;
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break;
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case AST_T38_TERMINATED:
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case AST_T38_REQUEST_TERMINATE:
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case AST_T38_REFUSED:
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*c_state = T38_STATE_REJECTED;
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break;
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case AST_T38_REQUEST_PARMS:
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default:
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/* No state change */
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break;
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}
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ast_debug(3, "Bridge %s T.38 state: %s: %d; %s: %d\n",
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bridge->uniqueid, ast_channel_name(state->bc0->chan), state->c0_state,
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ast_channel_name(state->bc1->chan), state->c1_state);
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break;
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}
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default:
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break;
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}
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break;
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default:
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break;
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}
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return ast_bridge_queue_everyone_else(bridge, bridge_channel, frame);
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}
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static int t38_bridge_compatible(struct ast_bridge *bridge)
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{
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struct ast_bridge_channel *bc0 = AST_LIST_FIRST(&bridge->channels);
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struct ast_bridge_channel *bc1 = AST_LIST_LAST(&bridge->channels);
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enum ast_t38_state c0_state;
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enum ast_t38_state c1_state;
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/* We must have two, and only two, channels in a T.38 bridge */
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if (bridge->num_channels != 2) {
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ast_debug(1, "Bridge '%s' can not use T.38 bridge as two channels are required\n",
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bridge->uniqueid);
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return 0;
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}
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/* We can be the bridge tech so long as one side is in the process
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* of negotiating T.38
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*/
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c0_state = ast_channel_get_t38_state(bc0->chan);
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c1_state = ast_channel_get_t38_state(bc1->chan);
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if (c0_state != T38_STATE_NEGOTIATING && c0_state != T38_STATE_NEGOTIATED
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&& c1_state != T38_STATE_NEGOTIATING && c1_state != T38_STATE_NEGOTIATED) {
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ast_debug(1, "Bridge '%s' can not use T.38 bridge: channel %s has T.38 state %d; channel %s has T.38 state %d\n",
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bridge->uniqueid, ast_channel_name(bc0->chan), c0_state, ast_channel_name(bc1->chan), c1_state);
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return 0;
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}
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return 1;
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}
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static struct ast_bridge_technology t38_bridge = {
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.name = "t38_bridge",
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.capabilities = AST_BRIDGE_CAPABILITY_1TO1MIX,
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.preference = AST_BRIDGE_PREFERENCE_BASE_1TO1MIX + 1,
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.create = t38_bridge_create,
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.destroy = t38_bridge_destroy,
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.start = t38_bridge_start,
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.stop = t38_bridge_stop,
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.leave = t38_bridge_leave,
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.write = t38_bridge_write,
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.compatible = t38_bridge_compatible,
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};
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static int unload_module(void)
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{
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ast_bridge_technology_unregister(&t38_bridge);
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return 0;
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}
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static int load_module(void)
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{
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if (ast_bridge_technology_register(&t38_bridge)) {
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return AST_MODULE_LOAD_DECLINE;
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}
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return AST_MODULE_LOAD_SUCCESS;
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}
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AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Two channel bridging module that maintains T.38 state");
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