res_pjsip_diversion.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * Kevin Harwell <kharwell@digium.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.
 */
 
/*** MODULEINFO
    <depend>pjproject</depend>
    <depend>res_pjsip</depend>
    <depend>res_pjsip_session</depend>
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include <pjsip.h>
#include <pjsip_ua.h>
 
#include "asterisk/res_pjsip.h"
#include "asterisk/res_pjsip_session.h"
#include "asterisk/callerid.h"
#include "asterisk/channel.h"
#include "asterisk/module.h"
#include "asterisk/strings.h"
 
static const pj_str_t diversion_name = { "Diversion", 9 };
static const pj_str_t history_info_name = { "History-Info", 12 };
static pj_str_t HISTINFO_SUPPORTED_NAME = { "histinfo", 8 };
 
/*!
 * \internal
 * \brief Determine if the given string is a SIP token.
 * \since 13.8.0
 *
 * \param str String to determine if is a SIP token.
 *
 * \note A token is defined by RFC3261 Section 25.1
 *
 * \return Non-zero if the string is a SIP token.
 */
static int sip_is_token(const char *str)
{
    int is_token;
 
    if (ast_strlen_zero(str)) {
        /* An empty string is not a token. */
        return 0;
    }
 
    is_token = 1;
    do {
        if (!isalnum(*str)
            && !strchr("-.!%*_+`'~", *str)) {
            /* The character is not allowed in a token. */
            is_token = 0;
            break;
        }
    } while (*++str);
 
    return is_token;
}
 
/*! \brief Diversion header reasons
 *
 * The core defines a bunch of constants used to define
 * redirecting reasons. This provides a translation table
 * between those and the strings which may be present in
 * a SIP Diversion header
 */
static const struct reasons {
    enum AST_REDIRECTING_REASON code;
    const char *text;
    const unsigned int cause;
} reason_table[] = {
    { AST_REDIRECTING_REASON_UNKNOWN, "unknown", 404 },
    { AST_REDIRECTING_REASON_USER_BUSY, "user-busy", 486 },
    { AST_REDIRECTING_REASON_NO_ANSWER, "no-answer", 408 },
    { AST_REDIRECTING_REASON_UNAVAILABLE, "unavailable", 503 },
    { AST_REDIRECTING_REASON_UNCONDITIONAL, "unconditional", 302 },
    { AST_REDIRECTING_REASON_TIME_OF_DAY, "time-of-day", 404 },
    { AST_REDIRECTING_REASON_DO_NOT_DISTURB, "do-not-disturb", 404 },
    { AST_REDIRECTING_REASON_DEFLECTION, "deflection", 480 },
    { AST_REDIRECTING_REASON_FOLLOW_ME, "follow-me", 404 },
    { AST_REDIRECTING_REASON_OUT_OF_ORDER, "out-of-service", 404 },
    { AST_REDIRECTING_REASON_AWAY, "away", 404 },
    { AST_REDIRECTING_REASON_CALL_FWD_DTE, "cf_dte", 404 },     /* Non-standard */
    { AST_REDIRECTING_REASON_SEND_TO_VM, "send_to_vm", 404 },   /* Non-standard */
};
 
static enum AST_REDIRECTING_REASON cause_to_reason(const unsigned long cause) {
    switch(cause) {
        case 302:
            return AST_REDIRECTING_REASON_UNCONDITIONAL;
        case 486:
            return AST_REDIRECTING_REASON_USER_BUSY;
        case 408:
            return AST_REDIRECTING_REASON_NO_ANSWER;
        case 480:
        case 487:
            return AST_REDIRECTING_REASON_DEFLECTION;
        case 503:
            return AST_REDIRECTING_REASON_UNAVAILABLE;
        default:
            return AST_REDIRECTING_REASON_UNKNOWN;
    }
}
 
static int add_supported(pjsip_tx_data *tdata)
{
    pjsip_supported_hdr *hdr;
    unsigned int i;
 
    hdr = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_SUPPORTED, NULL);
    if (!hdr) {
        /* insert a new Supported header */
        hdr = pjsip_supported_hdr_create(tdata->pool);
        if (!hdr) {
            return -1;
        }
 
        pjsip_msg_add_hdr(tdata->msg, (pjsip_hdr *)hdr);
    }
 
    /* Asterisk can send multiple "181 Call forwarded" in a single session,
     * we might have already modified Supported before
     */
    for (i = 0; i < hdr->count; ++i) {
        if (pj_stricmp(&hdr->values[i], &HISTINFO_SUPPORTED_NAME) == 0) {
            return 0;
        }
    }
 
    if (hdr->count >= PJSIP_GENERIC_ARRAY_MAX_COUNT) {
        return -1;
    }
 
    /* add on to the existing Supported header */
    pj_strassign(&hdr->values[hdr->count++], &HISTINFO_SUPPORTED_NAME);
 
    return 0;
}
 
static const char *reason_code_to_str(const struct ast_party_redirecting_reason *reason)
{
    int idx;
    int code;
 
    /* use specific string if given */
    if (!ast_strlen_zero(reason->str)) {
        return reason->str;
    }
 
    code = reason->code;
    for (idx = 0; idx < ARRAY_LEN(reason_table); ++idx) {
        if (code == reason_table[idx].code) {
            return reason_table[idx].text;
        }
    }
 
    return "unknown";
}
 
static const unsigned int reason_code_to_cause(const struct ast_party_redirecting_reason *reason)
{
    int idx;
    int code;
 
    code = reason->code;
    for (idx = 0; idx < ARRAY_LEN(reason_table); ++idx) {
        if (code == reason_table[idx].code) {
            return reason_table[idx].cause;
        }
    }
 
    return 404;
}
 
static pjsip_fromto_hdr *get_diversion_header(pjsip_rx_data *rdata)
{
    static const pj_str_t from_name = { "From", 4 };
 
    pjsip_generic_string_hdr *hdr;
    pj_str_t value;
    int size;
 
    if (!(hdr = pjsip_msg_find_hdr_by_name(rdata->msg_info.msg, &diversion_name, NULL))) {
        return NULL;
    }
 
    pj_strdup_with_null(rdata->tp_info.pool, &value, &hdr->hvalue);
 
    /* parse as a fromto header */
    return pjsip_parse_hdr(rdata->tp_info.pool, &from_name, value.ptr,
                   pj_strlen(&value), &size);
}
 
/* Asterisk keeps track of 2 things. The redirected from address and
 * the redirected to address. If first=0 method will get the most recent
 * redirection target for use as the redirected to address. If first=1
 * then this method will get the original redirection target (index=1)
 * for use as the redirected from address.
 */
static pjsip_fromto_hdr *get_history_info_header(pjsip_rx_data *rdata, const unsigned int first)
{
    static const pj_str_t from_name = { "From", 4 };
    pjsip_fromto_hdr * result_hdr = NULL;
 
    pjsip_generic_string_hdr *hdr = NULL;
 
    hdr = pjsip_msg_find_hdr_by_name(rdata->msg_info.msg, &history_info_name, NULL);
 
    if (!hdr) {
        return NULL;
    }
 
    do {
        static const pj_str_t index_name = { "index", 5 };
        pj_str_t value;
        int size;
        pjsip_fromto_hdr * fromto_hdr = NULL;
        pjsip_param * index = NULL;
 
        pj_strdup_with_null(rdata->tp_info.pool, &value, &hdr->hvalue);
 
        /* parse as a fromto header */
        fromto_hdr =  pjsip_parse_hdr(rdata->tp_info.pool, &from_name, value.ptr,
                       pj_strlen(&value), &size);
 
        if (fromto_hdr == NULL) {
            continue;
        }
 
        index = pjsip_param_find(&fromto_hdr->other_param, &index_name);
 
        if (index) {
            if (!pj_strcmp2(&index->value, "1")) {
                if (!first) {
                    continue;
                } else {
                    return fromto_hdr;
                }
            }
        }
 
        result_hdr = fromto_hdr;
 
    } while ((hdr = pjsip_msg_find_hdr_by_name(rdata->msg_info.msg, &history_info_name, hdr->next)));
 
    return result_hdr;
}
 
static void set_redirecting_value(char **dst, const pj_str_t *src)
{
    ast_free(*dst);
    *dst = ast_malloc(pj_strlen(src) + 1);
    if (*dst) {
        ast_copy_pj_str(*dst, src, pj_strlen(src) + 1);
    }
}
 
static void set_redirecting_id(pjsip_name_addr *name_addr, struct ast_party_id *data,
                   struct ast_set_party_id *update)
{
    pjsip_sip_uri *uri = pjsip_uri_get_uri(name_addr->uri);
    char *semi;
    pj_str_t uri_user;
 
    uri_user = uri->user;
 
    /* Always truncate redirecting number at a semicolon. */
    semi = pj_strchr(&uri_user, ';');
    if (semi) {
        /*
         * We need to be able to handle URI's looking like
         * "sip:1235557890;phone-context=national@x.x.x.x;user=phone"
         *
         * Where the uri->user field will result in:
         * "1235557890;phone-context=national"
         *
         * People don't care about anything after the semicolon
         * showing up on their displays even though the RFC
         * allows the semicolon.
         */
        pj_strset(&uri_user, (char *) pj_strbuf(&uri_user), semi - pj_strbuf(&uri_user));
    }
 
    if (pj_strlen(&uri_user)) {
        update->number = 1;
        data->number.valid = 1;
        set_redirecting_value(&data->number.str, &uri_user);
    }
 
    if (pj_strlen(&name_addr->display)) {
        update->name = 1;
        data->name.valid = 1;
        set_redirecting_value(&data->name.str, &name_addr->display);
    }
}
 
static void copy_redirecting_id(struct ast_party_id *dst, const struct ast_party_id *src,
                struct ast_set_party_id *update)
{
    ast_party_id_copy(dst, src);
 
    if (dst->number.valid) {
        update->number = 1;
    }
 
    if (dst->name.valid) {
        update->name = 1;
    }
}
 
static void set_redirecting_reason_by_cause(pjsip_name_addr *name_addr,
                   struct ast_party_redirecting_reason *data)
{
    static const pj_str_t cause_name = { "cause", 5 };
    pjsip_uri *uri = name_addr->uri;
    pjsip_param *cause = NULL;
    unsigned long cause_value = 0;
 
    if (!ast_sip_is_allowed_uri(uri)) {
        return;
    }
 
    cause = ast_sip_pjsip_uri_get_other_param(uri, &cause_name);
 
    if (!cause) {
        return;
    }
 
    cause_value = pj_strtoul(&cause->value);
 
    data->code = cause_to_reason(cause_value);
    ast_free(data->str);
    data->str = ast_strdup("");
}
 
static void set_redirecting_reason(pjsip_fromto_hdr *from_info, pjsip_name_addr *to_info,
                   struct ast_party_redirecting_reason *data)
{
    static const pj_str_t reason_name = { "reason", 6 };
    pjsip_param *reason = pjsip_param_find(&from_info->other_param, &reason_name);
    char *reason_str;
 
    if (!reason) {
        if (to_info) {
            set_redirecting_reason_by_cause(to_info, data);
        }
        return;
    }
 
    set_redirecting_value(&data->str, &reason->value);
    if (!data->str) {
        /* Oops, allocation failure */
        return;
    }
    reason_str = ast_strdupa(data->str);
 
    /* Remove any enclosing double-quotes */
    if (*reason_str == '"') {
        reason_str = ast_strip_quoted(reason_str, "\"", "\"");
    }
 
    data->code = ast_redirecting_reason_parse(reason_str);
    if (data->code < 0) {
        data->code = AST_REDIRECTING_REASON_UNKNOWN;
    } else {
        ast_free(data->str);
        data->str = ast_strdup("");
    }
}
 
static void set_redirecting(struct ast_sip_session *session,
                pjsip_fromto_hdr *from_info,
                pjsip_name_addr *to_info)
{
    struct ast_party_redirecting data;
    struct ast_set_party_redirecting update;
 
    if (!session->channel) {
        return;
    }
 
    ast_party_redirecting_init(&data);
    memset(&update, 0, sizeof(update));
 
    data.reason.code = AST_REDIRECTING_REASON_UNKNOWN;
    if (from_info) {
        set_redirecting_id((pjsip_name_addr*)from_info->uri,
            &data.from, &update.from);
        set_redirecting_reason(from_info, to_info, &data.reason);
        ast_set_party_id_all(&update.priv_to);
    } else {
        copy_redirecting_id(&data.from, &session->id, &update.from);
    }
 
    if (to_info) {
        set_redirecting_id(to_info, &data.to, &update.to);
    }
 
    ast_set_party_id_all(&update.priv_orig);
    ast_set_party_id_all(&update.priv_from);
    ast_set_party_id_all(&update.priv_to);
    ++data.count;
 
    ast_channel_set_redirecting(session->channel, &data, &update);
    /* Only queue an indication if it was due to a response */
    if (session->inv_session->role == PJSIP_ROLE_UAC) {
        ast_channel_queue_redirecting_update(session->channel, &data, &update);
    }
    ast_party_redirecting_free(&data);
}
 
static int diversion_incoming_request(struct ast_sip_session *session, pjsip_rx_data *rdata)
{
    pjsip_fromto_hdr *hdr = get_diversion_header(rdata);
 
    if (hdr) {
        set_redirecting(session, hdr, (pjsip_name_addr*)
                PJSIP_MSG_TO_HDR(rdata->msg_info.msg)->uri);
    } else {
        pjsip_fromto_hdr *history_info_to;
        pjsip_fromto_hdr *history_info_from;
        history_info_to  = get_history_info_header(rdata, 0);
 
        if (history_info_to) {
            /* If History-Info is present, then it will also include the original
               redirected-from in addition to the redirected-to */
            history_info_from = get_history_info_header(rdata, 1);
            set_redirecting(session, history_info_from, (pjsip_name_addr*)history_info_to->uri);
        }
    }
 
    return 0;
}
 
static void diversion_incoming_response(struct ast_sip_session *session, pjsip_rx_data *rdata)
{
    static const pj_str_t contact_name = { "Contact", 7 };
    static const pj_str_t contact_name_s = { "m", 1 };
 
    pjsip_status_line status = rdata->msg_info.msg->line.status;
    pjsip_fromto_hdr *div_hdr;
    pjsip_fromto_hdr *history_info_to;
    pjsip_fromto_hdr *history_info_from;
    pjsip_contact_hdr *contact_hdr;
 
    if ((status.code != 302) && (status.code != 181)) {
        return;
    }
 
    /* use the diversion header info if there is one. if not one then use the
       the history-info, if that doesn't exist, use session caller id info. if
       that doesn't exist use info from the To hdr*/
    if (!(div_hdr = get_diversion_header(rdata))) {
        history_info_to  = get_history_info_header(rdata, 0);
 
        if (history_info_to) {
            /* If History-Info is present, then it will also include the original
               redirected-from in addition to the redirected-to */
            history_info_from = get_history_info_header(rdata, 1);
            set_redirecting(session, history_info_from, (pjsip_name_addr*)history_info_to->uri);
            return;
        }
        if (!div_hdr && !session->id.number.valid) {
            div_hdr = PJSIP_MSG_TO_HDR(rdata->msg_info.msg);
        }
    }
 
 
    if (status.code == 302) {
        /* With 302, Contact indicates the final destination and possibly Diversion indicates the hop before */
        contact_hdr = pjsip_msg_find_hdr_by_names(rdata->msg_info.msg, &contact_name, &contact_name_s, NULL);
 
        set_redirecting(session, div_hdr, contact_hdr ? (pjsip_name_addr*)contact_hdr->uri :
                (pjsip_name_addr*)PJSIP_MSG_FROM_HDR(rdata->msg_info.msg)->uri);
    } else {
        /* With 181, Diversion is non-standard, but if present indicates the new final destination, and To indicating the original */
        set_redirecting(session, PJSIP_MSG_TO_HDR(rdata->msg_info.msg),
                div_hdr ? (pjsip_name_addr*)div_hdr->uri : NULL);
    }
}
 
/*!
 * \internal
 * \brief Adds diversion header information to an outbound SIP message
 *
 * \param tdata The outbound message
 * \param data The redirecting data used to fill parts of the diversion header
 */
static void add_diversion_header(pjsip_tx_data *tdata, struct ast_party_redirecting *data)
{
    static const pj_str_t reason_name = { "reason", 6 };
 
    pjsip_fromto_hdr *hdr;
    pjsip_name_addr *name_addr;
    pjsip_param *param;
    pjsip_fromto_hdr *old_hdr;
    const char *reason_str;
    const char *quote_str;
    char *reason_buf;
    pjsip_uri *base;
 
    struct ast_party_id *id = NULL;
    if (tdata->msg->type == PJSIP_REQUEST_MSG) {
        id = &data->from;
    } else {
        /* In responses indicate the new destination */
        id = &data->to;
    }
 
    base = PJSIP_MSG_FROM_HDR(tdata->msg)->uri;
 
    if (!id->number.valid || ast_strlen_zero(id->number.str)) {
        return;
    }
 
    hdr = pjsip_from_hdr_create(tdata->pool);
    hdr->type = PJSIP_H_OTHER;
    hdr->sname = hdr->name = diversion_name;
 
    name_addr = pjsip_uri_clone(tdata->pool, base);
 
    pj_strdup2(tdata->pool, &name_addr->display, id->name.str);
    pj_strdup2(tdata->pool, (pj_str_t *)ast_sip_pjsip_uri_get_username(name_addr->uri), id->number.str);
 
    param = PJ_POOL_ALLOC_T(tdata->pool, pjsip_param);
    param->name = reason_name;
 
    reason_str = reason_code_to_str(&data->reason);
 
    /* Reason is either already quoted or it is a token to not need quotes added. */
    quote_str = *reason_str == '\"' || sip_is_token(reason_str) ? "" : "\"";
 
    reason_buf = pj_pool_alloc(tdata->pool, strlen(reason_str) + 3);
    sprintf(reason_buf, "%s%s%s", quote_str, reason_str, quote_str);/* Safe */
 
    param->value = pj_str(reason_buf);
 
    pj_list_insert_before(&hdr->other_param, param);
 
    hdr->uri = (pjsip_uri *) name_addr;
    old_hdr = pjsip_msg_find_hdr_by_name(tdata->msg, &diversion_name, NULL);
    if (old_hdr) {
        pj_list_erase(old_hdr);
    }
    pjsip_msg_add_hdr(tdata->msg, (pjsip_hdr *)hdr);
}
 
/*!
 * \internal
 * \brief Adds history-info header information to an outbound SIP message
 *
 * \param tdata The outbound message
 * \param data The redirecting data used to fill parts of the history-info header
 */
static void add_history_info_header(pjsip_tx_data *tdata, struct ast_party_redirecting *data)
{
    static const pj_str_t index_name = { "index", 5 };
    static const pj_str_t cause_name = { "cause", 5 };
    static const pj_str_t first_index = { "1", 1 };
    static const pj_str_t last_index = { "1.1", 3 };
 
    pjsip_fromto_hdr *hdr;
    pjsip_name_addr *name_addr;
    pjsip_sip_uri *uri;
    pjsip_param *param;
    pjsip_fromto_hdr *old_hdr;
    unsigned int cause;
    char *cause_buf;
 
    struct ast_party_id *to = &data->to;
    struct ast_party_id *from = &data->from;
 
    pjsip_uri *base = PJSIP_MSG_TO_HDR(tdata->msg)->uri;
 
 
    hdr = pjsip_from_hdr_create(tdata->pool);
    hdr->type = PJSIP_H_OTHER;
    hdr->sname = hdr->name = history_info_name;
 
    name_addr = pjsip_uri_clone(tdata->pool, base);
    uri = pjsip_uri_get_uri(name_addr->uri);
 
    /* if no redirecting information, then TO is the original destination */
    if (from->number.valid && !ast_strlen_zero(from->number.str)) {
        pj_strdup2(tdata->pool, &name_addr->display, from->name.str);
        pj_strdup2(tdata->pool, &uri->user, from->number.str);
    }
 
    param = PJ_POOL_ALLOC_T(tdata->pool, pjsip_param);
    param->name = index_name;
    param->value = first_index;
 
 
    pj_list_insert_before(&hdr->other_param, param);
    hdr->uri = (pjsip_uri *) name_addr;
 
    while ((old_hdr = pjsip_msg_find_hdr_by_name(tdata->msg, &history_info_name, NULL)) != NULL) {
        pj_list_erase(old_hdr);
    }
 
    pjsip_msg_add_hdr(tdata->msg, (pjsip_hdr *)hdr);
 
    if (!to->number.valid || ast_strlen_zero(to->number.str)) {
        return;
    }
 
    hdr = pjsip_from_hdr_create(tdata->pool);
    hdr->type = PJSIP_H_OTHER;
    hdr->sname = hdr->name = history_info_name;
 
    name_addr = pjsip_uri_clone(tdata->pool, base);
    uri = pjsip_uri_get_uri(name_addr->uri);
 
    pj_strdup2(tdata->pool, &name_addr->display, to->name.str);
    pj_strdup2(tdata->pool, &uri->user, to->number.str);
 
    param = PJ_POOL_ALLOC_T(tdata->pool, pjsip_param);
    param->name = index_name;
    param->value = last_index;
    pj_list_insert_before(&hdr->other_param, param);
 
    param = PJ_POOL_ALLOC_T(tdata->pool, pjsip_param);
    param->name = cause_name;
    cause = reason_code_to_cause(&data->reason);
    cause_buf = pj_pool_alloc(tdata->pool, 4);
    snprintf(cause_buf, 4, "%ud", cause);
    param->value = pj_str(cause_buf);
    pj_list_insert_before(&uri->other_param, param);
    hdr->uri = (pjsip_uri *) name_addr;
 
    pjsip_msg_add_hdr(tdata->msg, (pjsip_hdr *)hdr);
}
 
static void get_redirecting_add_diversion(struct ast_sip_session *session, pjsip_tx_data *tdata)
{
    struct ast_party_redirecting *data;
 
    add_supported(tdata);
 
    if (session->channel && session->endpoint->id.send_diversion &&
        (data = ast_channel_redirecting(session->channel))->count) {
        add_diversion_header(tdata, data);
    }
    if (session->channel && session->endpoint->id.send_history_info) {
        data = ast_channel_redirecting(session->channel);
        add_history_info_header(tdata, data);
    }
}
 
/*!
 * \internal
 * \brief Adds a diversion header to an outgoing INVITE request if
 *  redirecting information is available.
 *
 * \param session The session on which the INVITE request is to be sent
 * \param tdata The outbound INVITE request
 */
static void diversion_outgoing_request(struct ast_sip_session *session, pjsip_tx_data *tdata)
{
    get_redirecting_add_diversion(session, tdata);
}
 
/*!
 * \internal
 * \brief Adds a diversion header to an outgoing 3XX response
 *
 * \param session The session on which the INVITE response is to be sent
 * \param tdata The outbound INVITE response
 */
static void diversion_outgoing_response(struct ast_sip_session *session, pjsip_tx_data *tdata)
{
    struct pjsip_status_line status = tdata->msg->line.status;
 
    /* add to 302 and 181 */
    if (PJSIP_IS_STATUS_IN_CLASS(status.code, 300) || (status.code == 181)) {
        get_redirecting_add_diversion(session, tdata);
    }
}
 
static struct ast_sip_session_supplement diversion_supplement = {
    .method = "INVITE",
    /* this supplement needs to be called after caller id
           and after the channel has been created */
    .priority = AST_SIP_SUPPLEMENT_PRIORITY_CHANNEL + 100,
    .incoming_request = diversion_incoming_request,
    .incoming_response = diversion_incoming_response,
    .outgoing_request = diversion_outgoing_request,
    .outgoing_response = diversion_outgoing_response,
    .response_priority = AST_SIP_SESSION_BEFORE_MEDIA,
};
 
static int load_module(void)
{
    /* Because we are passing static memory to pjsip, we need to make sure it
     * stays valid while we potentially have active sessions */
    ast_module_shutdown_ref(ast_module_info->self);
    ast_sip_session_register_supplement(&diversion_supplement);
    return AST_MODULE_LOAD_SUCCESS;
}
 
static int unload_module(void)
{
    ast_sip_session_unregister_supplement(&diversion_supplement);
    return 0;
}
 
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP Add Diversion Header Support",
    .support_level = AST_MODULE_SUPPORT_CORE,
    .load = load_module,
    .unload = unload_module,
    .load_pri = AST_MODPRI_APP_DEPEND,
    .requires = "res_pjsip,res_pjsip_session",
);