pjsip_message_filter.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2014-2016, Digium, Inc.
 *
 * Joshua Colp <jcolp@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.
 */
 
#include "asterisk.h"
 
#include <pjsip.h>
#include <pjsip_ua.h>
 
#include "asterisk/res_pjsip.h"
#include "asterisk/res_pjsip_session.h"
#include "include/res_pjsip_private.h"
#include "asterisk/module.h"
 
#define MOD_DATA_RESTRICTIONS "restrictions"
 
static pj_status_t filter_on_tx_message(pjsip_tx_data *tdata);
static pj_bool_t filter_on_rx_message(pjsip_rx_data *rdata);
 
/*! \brief Outgoing message modification restrictions */
struct filter_message_restrictions {
    /*! \brief Disallow modification of the From domain */
    unsigned int disallow_from_domain_modification;
};
 
static pjsip_module filter_module_transport = {
    .name = { "Message Filtering Transport", 27 },
    .id = -1,
    .priority = PJSIP_MOD_PRIORITY_TRANSPORT_LAYER,
    .on_rx_request = filter_on_rx_message,
};
 
static pjsip_module filter_module_tsx = {
    .name = { "Message Filtering TSX", 21 },
    .id = -1,
    .priority = PJSIP_MOD_PRIORITY_TSX_LAYER - 1,
    .on_tx_request = filter_on_tx_message,
    .on_tx_response = filter_on_tx_message,
};
 
/*! \brief Helper function to get (or allocate if not already present) restrictions on a message */
static struct filter_message_restrictions *get_restrictions(pjsip_tx_data *tdata)
{
    struct filter_message_restrictions *restrictions;
 
    restrictions = ast_sip_mod_data_get(tdata->mod_data, filter_module_tsx.id, MOD_DATA_RESTRICTIONS);
    if (restrictions) {
        return restrictions;
    }
 
    restrictions = PJ_POOL_ALLOC_T(tdata->pool, struct filter_message_restrictions);
    ast_sip_mod_data_set(tdata->pool, tdata->mod_data, filter_module_tsx.id, MOD_DATA_RESTRICTIONS, restrictions);
 
    return restrictions;
}
 
/*! \brief Callback invoked on non-session outgoing messages */
static void filter_outgoing_message(struct ast_sip_endpoint *endpoint, struct ast_sip_contact *contact, struct pjsip_tx_data *tdata)
{
    struct filter_message_restrictions *restrictions = get_restrictions(tdata);
 
    restrictions->disallow_from_domain_modification = !ast_strlen_zero(endpoint->fromdomain);
}
 
/*! \brief PJSIP Supplement for tagging messages with restrictions */
static struct ast_sip_supplement filter_supplement = {
    .priority = AST_SIP_SUPPLEMENT_PRIORITY_FIRST,
    .outgoing_request = filter_outgoing_message,
    .outgoing_response = filter_outgoing_message,
};
 
/*! \brief Callback invoked on session outgoing messages */
static void filter_session_outgoing_message(struct ast_sip_session *session, struct pjsip_tx_data *tdata)
{
    struct filter_message_restrictions *restrictions = get_restrictions(tdata);
 
    restrictions->disallow_from_domain_modification = !ast_strlen_zero(session->endpoint->fromdomain);
}
 
/*! \brief PJSIP Session Supplement for tagging messages with restrictions */
static struct ast_sip_session_supplement filter_session_supplement = {
    .priority = 1,
    .outgoing_request = filter_session_outgoing_message,
    .outgoing_response = filter_session_outgoing_message,
};
 
/*! \brief Helper function which returns a UDP transport bound to the given address and port */
static pjsip_transport *get_udp_transport(pj_str_t *address, int port)
{
    struct ao2_container *transport_states = ast_sip_get_transport_states();
    struct ast_sip_transport_state *transport_state;
    struct ao2_iterator iter;
    pjsip_transport *sip_transport = NULL;
 
    if (!transport_states) {
        return NULL;
    }
 
    for (iter = ao2_iterator_init(transport_states, 0); (transport_state = ao2_iterator_next(&iter)); ao2_ref(transport_state, -1)) {
        if (!transport_state->flow &&
            transport_state->type == AST_TRANSPORT_UDP &&
            !pj_strcmp(&transport_state->transport->local_name.host, address) &&
            transport_state->transport->local_name.port == port) {
            sip_transport = transport_state->transport;
            ao2_ref(transport_state, -1);
            break;
        }
    }
    ao2_iterator_destroy(&iter);
 
    ao2_ref(transport_states, -1);
 
    return sip_transport;
}
 
/*! \brief Helper function which determines if a transport is bound to any */
static int is_bound_any(pjsip_transport *transport)
{
    pj_uint32_t loop6[4] = {0, 0, 0, 0};
 
    if ((transport->local_addr.addr.sa_family == pj_AF_INET() &&
        transport->local_addr.ipv4.sin_addr.s_addr == PJ_INADDR_ANY) ||
        (transport->local_addr.addr.sa_family == pj_AF_INET6() &&
        !pj_memcmp(&transport->local_addr.ipv6.sin6_addr, loop6, sizeof(loop6)))) {
        return 1;
    }
 
    return 0;
}
 
/*! \brief Helper function which determines if the address within SDP should be rewritten */
static int multihomed_rewrite_sdp(struct pjmedia_sdp_session *sdp)
{
    if (!sdp->conn) {
        return 0;
    }
 
    /* If the host address is used in the SDP replace it with the address of what this is going out on */
    if ((!pj_strcmp2(&sdp->conn->addr_type, "IP4") && !pj_strcmp2(&sdp->conn->addr,
        ast_sip_get_host_ip_string(pj_AF_INET()))) ||
        (!pj_strcmp2(&sdp->conn->addr_type, "IP6") && !pj_strcmp2(&sdp->conn->addr,
        ast_sip_get_host_ip_string(pj_AF_INET6())))) {
        return 1;
    }
 
    return 0;
}
 
#define is_sip_uri(uri) \
    (PJSIP_URI_SCHEME_IS_SIP(uri) || PJSIP_URI_SCHEME_IS_SIPS(uri))
 
static void print_sanitize_debug(char *msg, pjsip_uri_context_e context, pjsip_sip_uri *uri)
{
#ifdef AST_DEVMODE
    char hdrbuf[512];
    int hdrbuf_len;
 
    hdrbuf_len = pjsip_uri_print(context, uri, hdrbuf, 512);
    hdrbuf[hdrbuf_len] = '\0';
    ast_debug(2, "%s: %s\n", msg, hdrbuf);
#endif
}
 
/* If in DEVMODE, prevent inlining to assist in debugging */
#ifdef AST_DEVMODE
#define FUNC_ATTRS __attribute__ ((noinline))
#else
#define FUNC_ATTRS
#endif
 
static void FUNC_ATTRS sanitize_tdata(pjsip_tx_data *tdata)
{
    static const pj_str_t x_name = { AST_SIP_X_AST_TXP, AST_SIP_X_AST_TXP_LEN };
    pjsip_param *x_transport;
    pjsip_sip_uri *uri;
    pjsip_hdr *hdr;
 
    if (tdata->msg->type == PJSIP_REQUEST_MSG) {
        if (is_sip_uri(tdata->msg->line.req.uri)) {
            uri = pjsip_uri_get_uri(tdata->msg->line.req.uri);
            print_sanitize_debug("Sanitizing Request", PJSIP_URI_IN_REQ_URI, uri);
            while ((x_transport = pjsip_param_find(&uri->other_param, &x_name))) {
                pj_list_erase(x_transport);
            }
        }
    }
 
    for (hdr = tdata->msg->hdr.next; hdr != &tdata->msg->hdr; hdr = hdr->next) {
        if (hdr->type == PJSIP_H_TO || hdr->type == PJSIP_H_FROM) {
            if (is_sip_uri(((pjsip_fromto_hdr *) hdr)->uri)) {
                uri = pjsip_uri_get_uri(((pjsip_fromto_hdr *) hdr)->uri);
                print_sanitize_debug("Sanitizing From/To header", PJSIP_URI_IN_FROMTO_HDR, uri);
                while ((x_transport = pjsip_param_find(&uri->other_param, &x_name))) {
                    pj_list_erase(x_transport);
                }
            }
        } else if (hdr->type == PJSIP_H_CONTACT) {
            if (!((pjsip_contact_hdr *) hdr)->star && is_sip_uri(((pjsip_contact_hdr *) hdr)->uri)) {
                uri = pjsip_uri_get_uri(((pjsip_contact_hdr *) hdr)->uri);
                print_sanitize_debug("Sanitizing Contact header", PJSIP_URI_IN_CONTACT_HDR, uri);
                while ((x_transport = pjsip_param_find(&uri->other_param, &x_name))) {
                    pj_list_erase(x_transport);
                }
            }
        }
    }
 
    pjsip_tx_data_invalidate_msg(tdata);
}
 
static pj_status_t filter_on_tx_message(pjsip_tx_data *tdata)
{
    struct filter_message_restrictions *restrictions =
        ast_sip_mod_data_get(tdata->mod_data, filter_module_transport.id, MOD_DATA_RESTRICTIONS);
    pjsip_tpmgr_fla2_param prm;
    pjsip_cseq_hdr *cseq;
    pjsip_via_hdr *via;
    pjsip_fromto_hdr *from;
    pjsip_tpselector sel;
    pjsip_sdp_info *sdp_info;
    pjmedia_sdp_session *sdp;
 
    sanitize_tdata(tdata);
 
    /* Use the destination information to determine what local interface this message will go out on */
    pjsip_tpmgr_fla2_param_default(&prm);
    prm.tp_type = tdata->tp_info.transport->key.type;
    pj_strset2(&prm.dst_host, tdata->tp_info.dst_name);
    prm.local_if = PJ_TRUE;
 
    if ((tdata->tp_info.transport->key.type != PJSIP_TRANSPORT_UDP) &&
        (tdata->tp_info.transport->key.type != PJSIP_TRANSPORT_UDP6)) {
        sel.type = PJSIP_TPSELECTOR_LISTENER;
        sel.u.listener = tdata->tp_info.transport->factory;
        prm.tp_sel = &sel;
    }
 
    /* If we can't get the local address use best effort and let it pass */
    if (pjsip_tpmgr_find_local_addr2(pjsip_endpt_get_tpmgr(ast_sip_get_pjsip_endpoint()), tdata->pool, &prm) != PJ_SUCCESS) {
        return PJ_SUCCESS;
    }
 
    /* For UDP we can have multiple transports so the port needs to be maintained */
    if (tdata->tp_info.transport->key.type == PJSIP_TRANSPORT_UDP ||
        tdata->tp_info.transport->key.type == PJSIP_TRANSPORT_UDP6) {
        prm.ret_port = tdata->tp_info.transport->local_name.port;
    }
 
    /* If the IP source differs from the existing transport see if we need to update it */
    if (pj_strcmp(&prm.ret_addr, &tdata->tp_info.transport->local_name.host)) {
 
        /* If the transport it is going out on is different reflect it in the message */
        if (tdata->tp_info.transport->key.type == PJSIP_TRANSPORT_UDP ||
            tdata->tp_info.transport->key.type == PJSIP_TRANSPORT_UDP6) {
            pjsip_transport *transport;
 
            transport = get_udp_transport(&prm.ret_addr, prm.ret_port);
 
            if (transport) {
                tdata->tp_info.transport = transport;
            }
        }
 
        /* If the chosen transport is not bound to any we can't use the source address as it won't get back to us */
        if (!is_bound_any(tdata->tp_info.transport)) {
            pj_strassign(&prm.ret_addr, &tdata->tp_info.transport->local_name.host);
        }
    } else {
        /* The transport chosen will deliver this but ensure it is updated with the right information */
        pj_strassign(&prm.ret_addr, &tdata->tp_info.transport->local_name.host);
    }
 
    /* If the message needs to be updated with new address do so */
    if (tdata->msg->type == PJSIP_REQUEST_MSG || !(cseq = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_CSEQ, NULL)) ||
        pj_strcmp2(&cseq->method.name, "REGISTER")) {
        pjsip_contact_hdr *contact = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_CONTACT, NULL);
        if (contact && (PJSIP_URI_SCHEME_IS_SIP(contact->uri) || PJSIP_URI_SCHEME_IS_SIPS(contact->uri))
            && !(tdata->msg->type == PJSIP_RESPONSE_MSG && tdata->msg->line.status.code / 100 == 3)) {
            pjsip_sip_uri *uri = pjsip_uri_get_uri(contact->uri);
 
            /* prm.ret_addr is allocated from the tdata pool OR the transport so it is perfectly fine to just do an assignment like this */
            pj_strassign(&uri->host, &prm.ret_addr);
            uri->port = prm.ret_port;
            ast_debug(5, "Re-wrote Contact URI host/port to %.*s:%d (this may be re-written again later)\n",
                (int)pj_strlen(&uri->host), pj_strbuf(&uri->host), uri->port);
 
            if (tdata->tp_info.transport->key.type == PJSIP_TRANSPORT_UDP ||
                tdata->tp_info.transport->key.type == PJSIP_TRANSPORT_UDP6) {
                uri->transport_param.slen = 0;
            } else {
                pj_strdup2(tdata->pool, &uri->transport_param, pjsip_transport_get_type_name(tdata->tp_info.transport->key.type));
            }
 
            pjsip_tx_data_invalidate_msg(tdata);
        }
    }
 
    if (tdata->msg->type == PJSIP_REQUEST_MSG && (via = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_VIA, NULL))) {
        pj_strassign(&via->sent_by.host, &prm.ret_addr);
        via->sent_by.port = prm.ret_port;
 
        pjsip_tx_data_invalidate_msg(tdata);
    }
 
    if (tdata->msg->type == PJSIP_REQUEST_MSG && (from = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_FROM, NULL)) &&
        (restrictions && !restrictions->disallow_from_domain_modification)) {
        pjsip_name_addr *id_name_addr = (pjsip_name_addr *)from->uri;
        pjsip_sip_uri *uri = pjsip_uri_get_uri(id_name_addr);
        pj_sockaddr ip;
 
        if (pj_strcmp2(&uri->host, "localhost") && pj_sockaddr_parse(pj_AF_UNSPEC(), 0, &uri->host, &ip) == PJ_SUCCESS) {
            pj_strassign(&uri->host, &prm.ret_addr);
            pjsip_tx_data_invalidate_msg(tdata);
        }
    }
 
    /* If there's no body in the tdata we can just return here. */
    if (!tdata->msg->body) {
        return PJ_SUCCESS;
    }
 
    /*
     * pjsip_get_sdp_info will search for an SDP even if it's in
     * a multipart message body.
     */
    sdp_info = pjsip_get_sdp_info(tdata->pool, tdata->msg->body, NULL, &pjsip_media_type_application_sdp);
    if (sdp_info->sdp_err != PJ_SUCCESS || !sdp_info->sdp) {
        return PJ_SUCCESS;
    }
 
    sdp = sdp_info->sdp;
 
    if (multihomed_rewrite_sdp(sdp)) {
        static const pj_str_t STR_IP4 = { "IP4", 3 };
        static const pj_str_t STR_IP6 = { "IP6", 3 };
        pj_str_t STR_IP;
        int stream;
 
        STR_IP = tdata->tp_info.transport->key.type & PJSIP_TRANSPORT_IPV6 ? STR_IP6 : STR_IP4;
 
        pj_strassign(&sdp->origin.addr, &prm.ret_addr);
        sdp->origin.addr_type = STR_IP;
        pj_strassign(&sdp->conn->addr, &prm.ret_addr);
        sdp->conn->addr_type = STR_IP;
 
        for (stream = 0; stream < sdp->media_count; ++stream) {
            if (sdp->media[stream]->conn) {
                pj_strassign(&sdp->media[stream]->conn->addr, &prm.ret_addr);
                sdp->media[stream]->conn->addr_type = STR_IP;
            }
        }
 
        pjsip_tx_data_invalidate_msg(tdata);
    }
 
    return PJ_SUCCESS;
}
 
enum uri_type {
    URI_TYPE_REQUEST = -1,
    URI_TYPE_TO = PJSIP_H_TO,
    URI_TYPE_FROM = PJSIP_H_FROM,
    URI_TYPE_CONTACT = PJSIP_H_CONTACT,
};
 
static void print_uri_debug(enum uri_type ut, pjsip_rx_data *rdata, pjsip_hdr *hdr)
{
#ifdef AST_DEVMODE
    pjsip_uri *local_uri = NULL;
    char hdrbuf[512];
    int hdrbuf_len;
    char *request_uri;
    pjsip_uri_context_e context = PJSIP_URI_IN_OTHER;
    char header_name[32];
 
    switch (ut) {
    case(URI_TYPE_REQUEST):
        context = PJSIP_URI_IN_REQ_URI;
        strcpy(header_name, "Request"); /* Safe */
        local_uri = rdata->msg_info.msg->line.req.uri;
        break;
    case(PJSIP_H_FROM):
        strcpy(header_name, "From"); /* Safe */
        context = PJSIP_URI_IN_FROMTO_HDR;
        local_uri = pjsip_uri_get_uri(((pjsip_from_hdr *)hdr)->uri);
        break;
    case(PJSIP_H_TO):
        strcpy(header_name, "To"); /* Safe */
        context = PJSIP_URI_IN_FROMTO_HDR;
        local_uri = pjsip_uri_get_uri(((pjsip_to_hdr *)hdr)->uri);
        break;
    case(PJSIP_H_CONTACT):
        strcpy(header_name, "Contact"); /* Safe */
        context = PJSIP_URI_IN_CONTACT_HDR;
        local_uri = pjsip_uri_get_uri(((pjsip_contact_hdr *)hdr)->uri);
        break;
    }
 
    hdrbuf_len = pjsip_uri_print(PJSIP_URI_IN_REQ_URI, rdata->msg_info.msg->line.req.uri, hdrbuf, 512);
    hdrbuf[hdrbuf_len] = '\0';
    request_uri = ast_strdupa(hdrbuf);
    hdrbuf_len = pjsip_uri_print(context, local_uri, hdrbuf, 512);
    hdrbuf[hdrbuf_len] = '\0';
 
    ast_debug(2, "There was a non sip(s) URI scheme in %s URI '%s' for request '%*.*s %s'\n",
        header_name, hdrbuf,
        (int)rdata->msg_info.msg->line.req.method.name.slen,
        (int)rdata->msg_info.msg->line.req.method.name.slen,
        rdata->msg_info.msg->line.req.method.name.ptr, request_uri);
#endif
}
 
/*!
 * /internal
 *
 * We want to make sure that any incoming requests don't already
 * have x-ast-* parameters in any URIs or we may get confused
 * if symmetric transport (x-ast-txp) or rewrite_contact (x-ast-orig-host)
 * is used later on.
 */
static void remove_x_ast_params(pjsip_uri *header_uri){
    pjsip_sip_uri *uri;
    pjsip_param *param;
 
    if (!header_uri) {
        return;
    }
 
    uri = pjsip_uri_get_uri(header_uri);
    if (!uri) {
        return;
    }
 
    param = uri->other_param.next;
 
    while (param != &uri->other_param) {
        /* We need to save off 'next' because pj_list_erase will remove it */
        pjsip_param *next = param->next;
 
        if (pj_strncmp2(&param->name, "x-ast-", 6) == 0) {
            pj_list_erase(param);
        }
        param = next;
    }
}
 
static pj_bool_t on_rx_process_uris(pjsip_rx_data *rdata)
{
    pjsip_contact_hdr *contact = NULL;
 
    if (rdata->msg_info.msg->type != PJSIP_REQUEST_MSG) {
        return PJ_FALSE;
    }
 
    if (!is_sip_uri(rdata->msg_info.msg->line.req.uri)) {
        print_uri_debug(URI_TYPE_REQUEST, rdata, NULL);
        pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata,
            PJSIP_SC_UNSUPPORTED_URI_SCHEME, NULL, NULL, NULL);
        return PJ_TRUE;
    }
    remove_x_ast_params(rdata->msg_info.msg->line.req.uri);
 
    if (!is_sip_uri(rdata->msg_info.from->uri)) {
        print_uri_debug(URI_TYPE_FROM, rdata, (pjsip_hdr *)rdata->msg_info.from);
        pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata,
            PJSIP_SC_UNSUPPORTED_URI_SCHEME, NULL, NULL, NULL);
        return PJ_TRUE;
    }
    remove_x_ast_params(rdata->msg_info.from->uri);
 
    if (!is_sip_uri(rdata->msg_info.to->uri)) {
        print_uri_debug(URI_TYPE_TO, rdata, (pjsip_hdr *)rdata->msg_info.to);
        pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata,
            PJSIP_SC_UNSUPPORTED_URI_SCHEME, NULL, NULL, NULL);
        return PJ_TRUE;
    }
    remove_x_ast_params(rdata->msg_info.to->uri);
 
    contact = (pjsip_contact_hdr *) pjsip_msg_find_hdr(
        rdata->msg_info.msg, PJSIP_H_CONTACT, NULL);
 
    if (!contact && pjsip_method_creates_dialog(&rdata->msg_info.msg->line.req.method)) {
        /* A contact header is required for dialog creating methods */
        static const pj_str_t missing_contact = { "Missing Contact header", 22 };
        pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 400,
                &missing_contact, NULL, NULL);
        return PJ_TRUE;
    }
 
    while (contact) {
        if (!contact->star && !is_sip_uri(contact->uri)) {
            print_uri_debug(URI_TYPE_CONTACT, rdata, (pjsip_hdr *)contact);
            pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata,
                PJSIP_SC_UNSUPPORTED_URI_SCHEME, NULL, NULL, NULL);
            return PJ_TRUE;
        }
        remove_x_ast_params(contact->uri);
 
        contact = (pjsip_contact_hdr *) pjsip_msg_find_hdr(
            rdata->msg_info.msg, PJSIP_H_CONTACT, contact->next);
    }
 
    return PJ_FALSE;
}
 
static pj_bool_t on_rx_process_symmetric_transport(pjsip_rx_data *rdata)
{
    pjsip_contact_hdr *contact;
    pjsip_sip_uri *uri;
    const char *transport_id;
    struct ast_sip_transport *transport;
    pjsip_param *x_transport;
 
    if (rdata->msg_info.msg->type != PJSIP_REQUEST_MSG) {
        return PJ_FALSE;
    }
 
    contact = pjsip_msg_find_hdr(rdata->msg_info.msg, PJSIP_H_CONTACT, NULL);
    if (!(contact && contact->uri
        && ast_begins_with(rdata->tp_info.transport->info, AST_SIP_X_AST_TXP ":"))) {
        return PJ_FALSE;
    }
 
    uri = pjsip_uri_get_uri(contact->uri);
 
    transport_id = rdata->tp_info.transport->info + AST_SIP_X_AST_TXP_LEN + 1;
    transport = ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "transport", transport_id);
 
    if (!(transport && transport->symmetric_transport)) {
        ao2_cleanup(transport);
        return PJ_FALSE;
    }
    ao2_cleanup(transport);
 
    x_transport = PJ_POOL_ALLOC_T(rdata->tp_info.pool, pjsip_param);
    x_transport->name = pj_strdup3(rdata->tp_info.pool, AST_SIP_X_AST_TXP);
    x_transport->value = pj_strdup3(rdata->tp_info.pool, transport_id);
 
    pj_list_insert_before(&uri->other_param, x_transport);
 
    ast_debug(1, "Set transport '%s' on %.*s from %.*s:%d\n", transport_id,
        (int)rdata->msg_info.msg->line.req.method.name.slen,
        rdata->msg_info.msg->line.req.method.name.ptr,
        (int)uri->host.slen, uri->host.ptr, uri->port);
 
    return PJ_FALSE;
}
 
static pj_bool_t filter_on_rx_message(pjsip_rx_data *rdata)
{
    pj_bool_t rc;
 
    rc = on_rx_process_uris(rdata);
    if (rc == PJ_TRUE) {
        return rc;
    }
 
    rc = on_rx_process_symmetric_transport(rdata);
    if (rc == PJ_TRUE) {
        return rc;
    }
 
    return PJ_FALSE;
}
 
void ast_res_pjsip_cleanup_message_filter(void)
{
    ast_sip_unregister_service(&filter_module_tsx);
    ast_sip_unregister_service(&filter_module_transport);
    ast_sip_unregister_supplement(&filter_supplement);
    ast_sip_session_unregister_supplement(&filter_session_supplement);
}
 
int ast_res_pjsip_init_message_filter(void)
{
    ast_sip_session_register_supplement(&filter_session_supplement);
    ast_sip_register_supplement(&filter_supplement);
 
    if (ast_sip_register_service(&filter_module_transport)) {
        ast_log(LOG_ERROR, "Could not register message filter module for incoming and outgoing requests\n");
        ast_res_pjsip_cleanup_message_filter();
        return -1;
    }
 
    if (ast_sip_register_service(&filter_module_tsx)) {
        ast_log(LOG_ERROR, "Could not register message filter module for incoming and outgoing requests\n");
        ast_res_pjsip_cleanup_message_filter();
        return -1;
    }
 
    return 0;
}