func_srv.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2010 Digium, Inc.
 *
 * 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 SRV Functions
 *
 * \author Mark Michelson <mmichelson@digium.com>
 *
 * \ingroup functions
 */
 
/*** MODULEINFO
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include "asterisk/module.h"
#include "asterisk/srv.h"
#include "asterisk/pbx.h"
#include "asterisk/app.h"
#include "asterisk/datastore.h"
#include "asterisk/channel.h"
 
/*** DOCUMENTATION
    <function name="SRVQUERY" language="en_US">
        <synopsis>
            Initiate an SRV query.
        </synopsis>
        <syntax>
            <parameter name="service" required="true">
                <para>The service for which to look up SRV records. An example would be something
                like <literal>_sip._udp.example.com</literal></para>
            </parameter>
        </syntax>
        <description>
            <para>This will do an SRV lookup of the given service.</para>
        </description>
    </function>
    <function name="SRVRESULT" language="en_US">
        <synopsis>
            Retrieve results from an SRVQUERY.
        </synopsis>
        <syntax>
            <parameter name="id" required="true">
                <para>The identifier returned by the SRVQUERY function.</para>
            </parameter>
            <parameter name="resultnum" required="true">
                <para>The number of the result that you want to retrieve.</para>
                <para>Results start at <literal>1</literal>. If this argument is specified
                as <literal>getnum</literal>, then it will return the total number of results
                that are available.</para>
            </parameter>
            <parameter name="field" required="false">
                <para>The field of the result to retrieve.</para>
                <para>The fields that can be retrieved are:</para>
                <enumlist>
                    <enum name="host"/>
                    <enum name="port"/>
                    <enum name="priority"/>
                    <enum name="weight"/>
                </enumlist>
            </parameter>
        </syntax>
        <description>
            <para>This function will retrieve results from a previous use
            of the SRVQUERY function.</para>
        </description>
    </function>
 ***/
 
struct srv_result_datastore {
    struct srv_context *context;
    char id[1];
};
 
static void srds_destroy_cb(void *data)
{
    struct srv_result_datastore *datastore = data;
    ast_srv_cleanup(&datastore->context);
    ast_free(datastore);
}
 
static const struct ast_datastore_info srv_result_datastore_info = {
    .type = "SRVQUERY",
    .destroy = srds_destroy_cb,
};
 
static struct srv_context *srv_datastore_setup(const char *service, struct ast_channel *chan)
{
    struct srv_result_datastore *srds;
    struct ast_datastore *datastore;
    const char *host;
    unsigned short port;
 
    if (!(srds = ast_calloc(1, sizeof(*srds) + strlen(service)))) {
        return NULL;
    }
 
    ast_autoservice_start(chan);
    if (ast_srv_lookup(&srds->context, service, &host, &port) < 0) {
        ast_autoservice_stop(chan);
        ast_log(LOG_NOTICE, "Error performing lookup of service '%s'\n", service);
        ast_free(srds);
        return NULL;
    }
    ast_autoservice_stop(chan);
 
    strcpy(srds->id, service);
 
    if (!(datastore = ast_datastore_alloc(&srv_result_datastore_info, srds->id))) {
        ast_srv_cleanup(&srds->context);
        ast_free(srds);
        return NULL;
    }
 
    datastore->data = srds;
    ast_channel_lock(chan);
    ast_channel_datastore_add(chan, datastore);
    ast_channel_unlock(chan);
    return srds->context;
}
 
static int srv_query_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
{
    struct ast_datastore *datastore;
 
    if (!chan) {
        ast_log(LOG_WARNING, "%s cannot be used without a channel\n", cmd);
        return -1;
    }
 
    if (ast_strlen_zero(data)) {
        ast_log(LOG_WARNING, "%s requires a service as an argument\n", cmd);
        return -1;
    }
 
    /* If they already called SRVQUERY for this service once,
     * we need to kill the old datastore.
     */
    ast_channel_lock(chan);
    datastore = ast_channel_datastore_find(chan, &srv_result_datastore_info, data);
    ast_channel_unlock(chan);
 
    if (datastore) {
        ast_channel_datastore_remove(chan, datastore);
        ast_datastore_free(datastore);
    }
 
    if (!srv_datastore_setup(data, chan)) {
        return -1;
    }
 
    ast_copy_string(buf, data, len);
 
    return 0;
}
 
static struct ast_custom_function srv_query_function = {
    .name = "SRVQUERY",
    .read = srv_query_read,
};
 
static int srv_result_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
{
    struct srv_result_datastore *srds;
    struct ast_datastore *datastore;
    struct srv_context *srv_context;
    char *parse;
    const char *host;
    unsigned short port, priority, weight;
    unsigned int num;
    AST_DECLARE_APP_ARGS(args,
        AST_APP_ARG(id);
        AST_APP_ARG(resultnum);
        AST_APP_ARG(field);
    );
 
    if (!chan) {
        ast_log(LOG_WARNING, "%s cannot be used without a channel\n", cmd);
        return -1;
    }
 
    if (ast_strlen_zero(data)) {
        ast_log(LOG_WARNING, "%s requires two arguments (id and resultnum)\n", cmd);
        return -1;
    }
 
    parse = ast_strdupa(data);
 
    AST_STANDARD_APP_ARGS(args, parse);
 
    ast_channel_lock(chan);
    datastore = ast_channel_datastore_find(chan, &srv_result_datastore_info, args.id);
    ast_channel_unlock(chan);
 
    if (!datastore) {
        /* They apparently decided to call SRVRESULT without first calling SRVQUERY.
         * No problem, we'll do the SRV lookup now.
         */
        srv_context = srv_datastore_setup(args.id, chan);
        if (!srv_context) {
            return -1;
        }
    } else {
        srds = datastore->data;
        srv_context = srds->context;
    }
 
    if (!strcasecmp(args.resultnum, "getnum")) {
        snprintf(buf, len, "%u", ast_srv_get_record_count(srv_context));
        return 0;
    }
 
    if (ast_strlen_zero(args.field)) {
        ast_log(LOG_ERROR, "A field must be provided when requesting SRV data\n");
        return -1;
    }
 
    if (sscanf(args.resultnum, "%30u", &num) != 1) {
        ast_log(LOG_ERROR, "Invalid value '%s' for resultnum to %s\n", args.resultnum, cmd);
        return -1;
    }
 
    if (ast_srv_get_nth_record(srv_context, num, &host, &port, &priority, &weight)) {
        ast_log(LOG_ERROR, "Failed to get record number %u for %s\n", num, cmd);
        return -1;
    }
 
    if (!strcasecmp(args.field, "host")) {
        ast_copy_string(buf, host, len);
    } else if (!strcasecmp(args.field, "port")) {
        snprintf(buf, len, "%d", port);
    } else if (!strcasecmp(args.field, "priority")) {
        snprintf(buf, len, "%d", priority);
    } else if (!strcasecmp(args.field, "weight")) {
        snprintf(buf, len, "%d", weight);
    } else {
        ast_log(LOG_WARNING, "Unrecognized SRV field '%s'\n", args.field);
        return -1;
    }
 
    return 0;
}
 
static struct ast_custom_function srv_result_function = {
    .name = "SRVRESULT",
    .read = srv_result_read,
};
 
static int unload_module(void)
{
    int res = 0;
 
    res |= ast_custom_function_unregister(&srv_query_function);
    res |= ast_custom_function_unregister(&srv_result_function);
 
    return res;
}
 
static int load_module(void)
{
    int res = ast_custom_function_register(&srv_query_function);
    if (res < 0) {
        return AST_MODULE_LOAD_DECLINE;
    }
    res = ast_custom_function_register(&srv_result_function);
    if (res < 0) {
        return AST_MODULE_LOAD_DECLINE;
    }
 
    return AST_MODULE_LOAD_SUCCESS;;
}
 
AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "SRV related dialplan functions");