res_audiosocket.c

Go to the documentation of this file.

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2019, CyCore Systems, Inc
 *
 * Seán C McCord <scm@cycoresys.com
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */
 
/*! \file
 *
 * \brief AudioSocket support for Asterisk
 *
 * \author Seán C McCord <scm@cycoresys.com>
 *
 */
 
/*** MODULEINFO
    <support_level>extended</support_level>
 ***/
 
#include "asterisk.h"
#include "errno.h"
#include <uuid/uuid.h>
#include <arpa/inet.h>  /* For byte-order conversion. */
 
#include "asterisk/file.h"
#include "asterisk/res_audiosocket.h"
#include "asterisk/channel.h"
#include "asterisk/module.h"
#include "asterisk/uuid.h"
#include "asterisk/format_cache.h"
 
#define MODULE_DESCRIPTION  "AudioSocket support functions for Asterisk"
 
#define MAX_CONNECT_TIMEOUT_MSEC 2000
 
/*!
 * \internal
 * \brief Attempt to complete the audiosocket connection.
 *
 * \param server Url that we are trying to connect to.
 * \param addr Address that host was resolved to.
 * \param netsockfd File descriptor of socket.
 *
 * \retval 0 when connection is succesful.
 * \retval 1 when there is an error.
 */
static int handle_audiosocket_connection(const char *server,
    const struct ast_sockaddr addr, const int netsockfd)
{
    struct pollfd pfds[1];
    int res, conresult;
    socklen_t reslen;
 
    reslen = sizeof(conresult);
 
    pfds[0].fd = netsockfd;
    pfds[0].events = POLLOUT;
 
    while ((res = ast_poll(pfds, 1, MAX_CONNECT_TIMEOUT_MSEC)) != 1) {
        if (errno != EINTR) {
            if (!res) {
                ast_log(LOG_WARNING, "AudioSocket connection to '%s' timed"
                    "out after MAX_CONNECT_TIMEOUT_MSEC (%d) milliseconds.\n",
                    server, MAX_CONNECT_TIMEOUT_MSEC);
            } else {
                ast_log(LOG_WARNING, "Connect to '%s' failed: %s\n", server,
                    strerror(errno));
            }
 
            return -1;
        }
    }
 
    if (getsockopt(pfds[0].fd, SOL_SOCKET, SO_ERROR, &conresult, &reslen) < 0) {
        ast_log(LOG_WARNING, "Connection to '%s' failed with error: %s\n",
            ast_sockaddr_stringify(&addr), strerror(errno));
        return -1;
    }
 
    if (conresult) {
        ast_log(LOG_WARNING, "Connecting to '%s' failed for url '%s': %s\n",
            ast_sockaddr_stringify(&addr), server, strerror(conresult));
        return -1;
    }
 
    return 0;
}
 
const int ast_audiosocket_connect(const char *server, struct ast_channel *chan)
{
    int s = -1;
    struct ast_sockaddr *addrs = NULL;
    int num_addrs = 0, i = 0;
 
    if (chan && ast_autoservice_start(chan) < 0) {
        ast_log(LOG_WARNING, "Failed to start autoservice for channel "
            "'%s'\n", ast_channel_name(chan));
        goto end;
    }
 
    if (ast_strlen_zero(server)) {
        ast_log(LOG_ERROR, "No AudioSocket server provided\n");
        goto end;
    }
 
    if (!(num_addrs = ast_sockaddr_resolve(&addrs, server, PARSE_PORT_REQUIRE,
        AST_AF_UNSPEC))) {
        ast_log(LOG_ERROR, "Failed to resolve AudioSocket service using '%s' - "
            "requires a valid hostname and port\n", server);
        goto end;
    }
 
    /* Connect to AudioSocket service */
    for (i = 0; i < num_addrs; i++) {
 
        if (!ast_sockaddr_port(&addrs[i])) {
            /* If there's no port, other addresses should have the
             * same problem. Stop here.
             */
            ast_log(LOG_ERROR, "No port provided for '%s'\n",
                ast_sockaddr_stringify(&addrs[i]));
            s = -1;
            goto end;
        }
 
        if ((s = ast_socket_nonblock(addrs[i].ss.ss_family, SOCK_STREAM,
            IPPROTO_TCP)) < 0) {
            ast_log(LOG_WARNING, "Unable to create socket: '%s'\n", strerror(errno));
            continue;
        }
 
        /*
         * Disable Nagle's algorithm by setting the TCP_NODELAY socket option.
         * This reduces latency by preventing delays caused by packet buffering.
         */
        if (setsockopt(s, IPPROTO_TCP, TCP_NODELAY, &(int){1}, sizeof(int)) < 0) {
            ast_log(LOG_ERROR, "Failed to set TCP_NODELAY on AudioSocket: %s\n", strerror(errno));
        }
 
        if (ast_connect(s, &addrs[i]) && errno == EINPROGRESS) {
 
            if (handle_audiosocket_connection(server, addrs[i], s)) {
                close(s);
                continue;
            }
 
        } else {
            ast_log(LOG_ERROR, "Connection to '%s' failed with unexpected error: %s\n",
                ast_sockaddr_stringify(&addrs[i]), strerror(errno));
            close(s);
            s = -1;
        }
 
        break;
    }
 
end:
    if (addrs) {
        ast_free(addrs);
    }
 
    if (chan && ast_autoservice_stop(chan) < 0) {
        ast_log(LOG_WARNING, "Failed to stop autoservice for channel '%s'\n",
        ast_channel_name(chan));
        close(s);
        return -1;
    }
 
    if (i == num_addrs) {
        ast_log(LOG_ERROR, "Failed to connect to AudioSocket service\n");
        close(s);
        return -1;
    }
 
    return s;
}
 
const int ast_audiosocket_init(const int svc, const char *id)
{
    uuid_t uu;
    int ret = 0;
    uint8_t buf[3 + 16];
 
    if (ast_strlen_zero(id)) {
        ast_log(LOG_ERROR, "No UUID for AudioSocket\n");
        return -1;
    }
 
    if (uuid_parse(id, uu)) {
        ast_log(LOG_ERROR, "Failed to parse UUID '%s'\n", id);
        return -1;
    }
 
    buf[0] = AST_AUDIOSOCKET_KIND_UUID;
    buf[1] = 0x00;
    buf[2] = 0x10;
    memcpy(buf + 3, uu, 16);
 
    if (write(svc, buf, 3 + 16) != 3 + 16) {
        ast_log(LOG_WARNING, "Failed to write data to AudioSocket because: %s\n", strerror(errno));
        ret = -1;
    }
 
    return ret;
}
 
const int ast_audiosocket_send_frame(const int svc, const struct ast_frame *f)
{
    int datalen = f->datalen;
    if (f->frametype == AST_FRAME_DTMF) {
        datalen = 1;
    }
 
    {
        uint8_t buf[3 + datalen];
        uint16_t *length = (uint16_t *) &buf[1];
 
        /* Audio format is 16-bit, 8kHz signed linear mono for dialplan app,
            depends on agreed upon audio codec for channel driver interface. */
        switch (f->frametype) {
            case AST_FRAME_VOICE:
                buf[0] = AST_AUDIOSOCKET_KIND_AUDIO;
                *length = htons(datalen);
                memcpy(&buf[3], f->data.ptr, datalen);
                break;
            case AST_FRAME_DTMF:
                buf[0] = AST_AUDIOSOCKET_KIND_DTMF;
                buf[3] = (uint8_t) f->subclass.integer;
                *length = htons(1);
                break;
            default:
                ast_log(LOG_ERROR, "Unsupported frame type %d for AudioSocket\n", f->frametype);
                return -1;
        }
 
        if (write(svc, buf, 3 + datalen) != 3 + datalen) {
            ast_log(LOG_WARNING, "Failed to write data to AudioSocket because: %s\n", strerror(errno));
            return -1;
        }
    }
 
    return 0;
}
 
struct ast_frame *ast_audiosocket_receive_frame(const int svc)
{
    return ast_audiosocket_receive_frame_with_hangup(svc, NULL);
}
 
struct ast_frame *ast_audiosocket_receive_frame_with_hangup(const int svc,
    int *const hangup)
{
    int i = 0, n = 0, ret = 0;
    struct ast_frame f = {
        .frametype = AST_FRAME_VOICE,
        .subclass.format = ast_format_slin,
        .src = "AudioSocket",
        .mallocd = AST_MALLOCD_DATA,
    };
    uint8_t header[3];
    uint8_t *kind = &header[0];
    uint16_t *length = (uint16_t *) &header[1];
    uint8_t *data;
 
    if (hangup) {
        *hangup = 0;
    }
 
    n = read(svc, &header, 3);
    if (n == -1) {
        ast_log(LOG_WARNING, "Failed to read header from AudioSocket because: %s\n", strerror(errno));
        return NULL;
    }
 
    if (n == 0 || *kind == AST_AUDIOSOCKET_KIND_HANGUP) {
        /* Socket closure or requested hangup. */
        if (hangup) {
            *hangup = 1;
        }
        return NULL;
    }
 
    if (*kind != AST_AUDIOSOCKET_KIND_AUDIO) {
        ast_log(LOG_ERROR, "Received AudioSocket message other than hangup or audio, refer to protocol specification for valid message types\n");
        return NULL;
    }
 
    /* Swap endianess of length if needed. */
    *length = ntohs(*length);
    if (*length < 1) {
        ast_log(LOG_ERROR, "Invalid message length received from AudioSocket server. \n");
        return NULL;
    }
 
    data = ast_malloc(*length);
    if (!data) {
        ast_log(LOG_ERROR, "Failed to allocate for data from AudioSocket\n");
        return NULL;
    }
 
    ret = 0;
    n = 0;
    i = 0;
    while (i < *length) {
        n = read(svc, data + i, *length - i);
        if (n == -1) {
            if (errno == EAGAIN || errno == EWOULDBLOCK) {
                int poll_result = ast_wait_for_input(svc, 5);
 
                if (poll_result == 1) {
                    continue;
                } else if (poll_result == 0) {
                    ast_log(LOG_WARNING, "Poll timed out while waiting for data\n");
                } else {
                    ast_log(LOG_WARNING, "Poll error: %s\n", strerror(errno));
                }
            }
 
            ast_log(LOG_ERROR, "Failed to read payload from AudioSocket: %s\n", strerror(errno));
            ret = -1;
            break;
        }
        if (n == 0) {
            ast_log(LOG_ERROR, "Insufficient payload read from AudioSocket\n");
            ret = -1;
            break;
        }
        i += n;
    }
 
    if (ret != 0) {
        ast_free(data);
        return NULL;
    }
 
    f.data.ptr = data;
    f.datalen = *length;
    f.samples = *length / 2;
 
    /* The frame steals data, so it doesn't need to be freed here */
    return ast_frisolate(&f);
}
 
static int load_module(void)
{
    ast_verb(5, "Loading AudioSocket Support module\n");
    return AST_MODULE_LOAD_SUCCESS;
}
 
static int unload_module(void)
{
    ast_verb(5, "Unloading AudioSocket Support module\n");
    return AST_MODULE_LOAD_SUCCESS;
}
 
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS | AST_MODFLAG_LOAD_ORDER, "AudioSocket support",
    .support_level = AST_MODULE_SUPPORT_EXTENDED,
    .load = load_module,
    .unload = unload_module,
    .load_pri = AST_MODPRI_CHANNEL_DEPEND,
);