res_pjsip_caller_id.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * Mark Michelson <[email protected]>
 *
 * 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/channel.h"
#include "asterisk/module.h"
#include "asterisk/callerid.h"
#include "asterisk/conversions.h"

/*!
 * \internal
 * \brief Set an ast_party_id name and number based on an identity header.
 * \param hdr From, P-Asserted-Identity, or Remote-Party-ID header on incoming message
 * \param[out] id The ID to set data on
 */
static void set_id_from_hdr(pjsip_fromto_hdr *hdr, struct ast_party_id *id)
{
   char cid_name[AST_CHANNEL_NAME];
   char cid_num[AST_CHANNEL_NAME];
   pjsip_sip_uri *uri;
   pjsip_name_addr *id_name_addr = (pjsip_name_addr *) hdr->uri;
   char *semi;

   uri = pjsip_uri_get_uri(id_name_addr);
   ast_copy_pj_str(cid_name, &id_name_addr->display, sizeof(cid_name));
   ast_copy_pj_str(cid_num, &uri->user, sizeof(cid_num));

   /* Always truncate caller-id number at a semicolon. */
   semi = strchr(cid_num, ';');
   if (semi) {
      /*
       * We need to be able to handle URI's looking like
       * "sip:1235557890;[email protected];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.
       */
      *semi = '\0';
   }

   ast_free(id->name.str);
   id->name.str = ast_strdup(cid_name);
   if (!ast_strlen_zero(cid_name)) {
      id->name.valid = 1;
   }
   ast_free(id->number.str);
   id->number.str = ast_strdup(cid_num);
   if (!ast_strlen_zero(cid_num)) {
      id->number.valid = 1;
   }
}

/*!
 * \internal
 * \brief Get a P-Asserted-Identity or Remote-Party-ID header from an incoming message
 *
 * This function will parse the header as if it were a From header. This allows for us
 * to easily manipulate the URI, as well as add, modify, or remove parameters from the
 * header
 *
 * \param rdata The incoming message
 * \param header_name The name of the ID header to find
 * \retval NULL No ID header present or unable to parse ID header
 * \retval non-NULL The parsed ID header
 */
static pjsip_fromto_hdr *get_id_header(pjsip_rx_data *rdata, const pj_str_t *header_name)
{
   static const pj_str_t from = { "From", 4 };
   pj_str_t header_content;
   pjsip_fromto_hdr *parsed_hdr;
   pjsip_generic_string_hdr *ident = pjsip_msg_find_hdr_by_name(rdata->msg_info.msg,
         header_name, NULL);
   int parsed_len;

   if (!ident) {
      return NULL;
   }
   
   ast_log(LOG_WARNING, "Doing checks now\n");
   
   if (!(rdata)) {
      ast_log(LOG_WARNING, "NULL 1\n");
   }
   if (!ident) {
      ast_log(LOG_WARNING, "NULL 3\n");
   }
   
   if (!rdata->tp_info.pool) {
      ast_log(LOG_WARNING, "NULL 11\n");
   }
   if (!&ident->hvalue) {
      ast_log(LOG_WARNING, "NULL 13\n");
   }
   
   ast_log(LOG_WARNING, "strlens %lu %lu\n", pj_strlen(&header_content), pj_strlen(&ident->hvalue));
   

   pj_strdup_with_null(rdata->tp_info.pool, &header_content, &ident->hvalue);

   parsed_hdr = pjsip_parse_hdr(rdata->tp_info.pool, &from, header_content.ptr,
         pj_strlen(&header_content), &parsed_len);

   if (!parsed_hdr) {
      return NULL;
   }

   return parsed_hdr;
}

/*!
 * \internal
 * \brief Set an ANI2 integer based on OLI data in a From header
 *
 * This uses the contents of a From header in order to set Originating Line information.
 *
 * \param rdata The incoming message
 * \param ani2 The ANI2 field to set
 * \retval 0 Successfully parsed From header
 * \retval non-zero Could not parse From header
 */
static int set_id_from_oli(pjsip_rx_data *rdata, int *ani2)
{
   #define MAX_OLI_DIGITS 2
   char oli[MAX_OLI_DIGITS + 1];
   static const pj_str_t from = { "From", 4 };
   static const pj_str_t oli_str1 = { "oli", 3 };
   static const pj_str_t oli_str2 = { "isup-oli", 8 };
   static const pj_str_t oli_str3 = { "ss7-oli", 7 };
   const pjsip_param *oli1, *oli2, *oli3;
   pjsip_fromto_hdr *from_hdr = get_id_header(rdata, &from);
   if (!from_hdr) {
      return 0;
   }
   if ((oli1 = pjsip_param_find(&from_hdr->other_param, &oli_str1))) {
      ast_copy_pj_str(oli, &oli1->value, MAX_OLI_DIGITS);
      return ast_str_to_int(oli, ani2);
   } else if ((oli2 = pjsip_param_find(&from_hdr->other_param, &oli_str2))) {
      ast_copy_pj_str(oli, &oli2->value, MAX_OLI_DIGITS);
      return ast_str_to_int(oli, ani2);
   } else if ((oli3 = pjsip_param_find(&from_hdr->other_param, &oli_str3))) {
      ast_copy_pj_str(oli, &oli3->value, MAX_OLI_DIGITS);
      return ast_str_to_int(oli, ani2);
   }
   return 0;
}

/*!
 * \internal
 * \brief Set an ast_party_id structure based on data in a P-Asserted-Identity header
 *
 * This makes use of \ref set_id_from_hdr for setting name and number. It uses
 * the contents of a Privacy header in order to set presentation information.
 *
 * \param rdata The incoming message
 * \param[out] id The ID to set
 * \retval 0 Successfully set the party ID
 * \retval non-zero Could not set the party ID
 */
static int set_id_from_pai(pjsip_rx_data *rdata, struct ast_party_id *id)
{
   static const pj_str_t pai_str = { "P-Asserted-Identity", 19 };
   static const pj_str_t privacy_str = { "Privacy", 7 };
   pjsip_fromto_hdr *pai_hdr = get_id_header(rdata, &pai_str);
   pjsip_generic_string_hdr *privacy;

   if (!pai_hdr) {
      return -1;
   }

   set_id_from_hdr(pai_hdr, id);

   if (!id->number.valid) {
      return -1;
   }

   privacy = pjsip_msg_find_hdr_by_name(rdata->msg_info.msg, &privacy_str, NULL);
   if (!privacy || !pj_stricmp2(&privacy->hvalue, "none")) {
      id->number.presentation = AST_PRES_ALLOWED_USER_NUMBER_NOT_SCREENED;
      id->name.presentation = AST_PRES_ALLOWED_USER_NUMBER_NOT_SCREENED;
   } else {
      id->number.presentation = AST_PRES_PROHIB_USER_NUMBER_NOT_SCREENED;
      id->name.presentation = AST_PRES_PROHIB_USER_NUMBER_NOT_SCREENED;
   }

   return 0;
}

/*!
 * \internal
 * \brief Set an ast_party_id structure based on data in a Remote-Party-ID header
 *
 * This makes use of \ref set_id_from_hdr for setting name and number. It uses
 * the privacy and screen parameters in order to set presentation information.
 *
 * \param rdata The incoming message
 * \param[out] id The ID to set
 * \retval 0 Succesfully set the party ID
 * \retval non-zero Could not set the party ID
 */
static int set_id_from_rpid(pjsip_rx_data *rdata, struct ast_party_id *id)
{
   static const pj_str_t rpid_str = { "Remote-Party-ID", 15 };
   static const pj_str_t privacy_str = { "privacy", 7 };
   static const pj_str_t screen_str = { "screen", 6 };
   pjsip_fromto_hdr *rpid_hdr = get_id_header(rdata, &rpid_str);
   pjsip_param *screen;
   pjsip_param *privacy;

   if (!rpid_hdr) {
      return -1;
   }

   set_id_from_hdr(rpid_hdr, id);

   if (!id->number.valid) {
      return -1;
   }

   privacy = pjsip_param_find(&rpid_hdr->other_param, &privacy_str);
   screen = pjsip_param_find(&rpid_hdr->other_param, &screen_str);
   if (privacy && !pj_stricmp2(&privacy->value, "full")) {
      id->number.presentation = AST_PRES_RESTRICTED;
      id->name.presentation = AST_PRES_RESTRICTED;
   } else {
      id->number.presentation = AST_PRES_ALLOWED;
      id->name.presentation = AST_PRES_ALLOWED;
   }
   if (screen && !pj_stricmp2(&screen->value, "yes")) {
      id->number.presentation |= AST_PRES_USER_NUMBER_PASSED_SCREEN;
      id->name.presentation |= AST_PRES_USER_NUMBER_PASSED_SCREEN;
   } else {
      id->number.presentation |= AST_PRES_USER_NUMBER_UNSCREENED;
      id->name.presentation |= AST_PRES_USER_NUMBER_UNSCREENED;
   }

   return 0;
}

/*!
 * \internal
 * \brief Set an ast_party_id structure based on data in a From
 *
 * This makes use of \ref set_id_from_hdr for setting name and number. It uses
 * no information from the message in order to set privacy. It relies on endpoint
 * configuration for privacy information.
 *
 * \param rdata The incoming message
 * \param[out] id The ID to set
 * \retval 0 Succesfully set the party ID
 * \retval non-zero Could not set the party ID
 */
static int set_id_from_from(struct pjsip_rx_data *rdata, struct ast_party_id *id)
{
   pjsip_fromto_hdr *from = pjsip_msg_find_hdr(rdata->msg_info.msg,
         PJSIP_H_FROM, rdata->msg_info.msg->hdr.next);

   if (!from) {
      /* This had better not happen */
      return -1;
   }

   set_id_from_hdr(from, id);

   if (!id->number.valid) {
      return -1;
   }

   return 0;
}

/*!
 * \internal
 * \brief Determine if a connected line update should be queued
 *
 * This uses information about the session and the ID that would be queued
 * in the connected line update in order to determine if we should queue
 * a connected line update.
 *
 * \param session The session whose channel we wish to queue the connected line update on
 * \param id The identification information that would be queued on the connected line update
 * \retval 0 We should not queue a connected line update
 * \retval non-zero We should queue a connected line update
 */
static int should_queue_connected_line_update(const struct ast_sip_session *session, const struct ast_party_id *id)
{
   /* Invalid number means no update */
   if (!id->number.valid) {
      return 0;
   }

   /* If the session has never communicated an update or if the
    * new ID has a different number than the session, then we
    * should queue an update
    */
   if (ast_strlen_zero(session->id.number.str) ||
         strcmp(session->id.number.str, id->number.str)) {
      return 1;
   }

   /* By making it to this point, it means the number is not enough
    * to determine if an update should be sent. Now we look at
    * the name
    */

   /* If the number couldn't warrant an update and the name is
    * invalid, then no update
    */
   if (!id->name.valid) {
      return 0;
   }

   /* If the name has changed or we don't have a name set for the
    * session, then we should send an update
    */
   if (ast_strlen_zero(session->id.name.str) ||
         strcmp(session->id.name.str, id->name.str)) {
      return 1;
   }

   /* Neither the name nor the number have changed. No update */
   return 0;
}

/*!
 * \internal
 * \brief Queue a connected line update on a session's channel.
 * \param session The session whose channel should have the connected line update queued upon.
 * \param id The identification information to place in the connected line update
 */
static void queue_connected_line_update(struct ast_sip_session *session, const struct ast_party_id *id)
{
   struct ast_party_connected_line connected;
   struct ast_party_caller caller;

   /* Fill connected line information */
   ast_party_connected_line_init(&connected);
   connected.id = *id;
   connected.id.tag = session->endpoint->id.self.tag;
   connected.source = AST_CONNECTED_LINE_UPDATE_SOURCE_ANSWER;

   /* Save to channel driver copy */
   ast_party_id_copy(&session->id, &connected.id);

   /* Update our channel CALLERID() */
   ast_party_caller_init(&caller);
   caller.id = connected.id;
   caller.ani = connected.id;
   caller.ani2 = ast_channel_caller(session->channel)->ani2;
   ast_channel_set_caller_event(session->channel, &caller, NULL);

   /* Tell peer about the new connected line information. */
   ast_channel_queue_connected_line_update(session->channel, &connected, NULL);
}

/*!
 * \internal
 * \brief Make updates to connected line information based on an incoming request.
 *
 * This will get identity information from an incoming request. Once the identification is
 * retrieved, we will check if the new information warrants a connected line update and queue
 * a connected line update if so.
 *
 * \param session The session on which we received an incoming request
 * \param rdata The incoming request
 */
static void update_incoming_connected_line(struct ast_sip_session *session, pjsip_rx_data *rdata)
{
   struct ast_party_id id;

   if (!session->endpoint->id.trust_connected_line
      || !session->endpoint->id.trust_inbound) {
      return;
   }

   ast_party_id_init(&id);
   if (!set_id_from_pai(rdata, &id) || !set_id_from_rpid(rdata, &id)) {
      if (should_queue_connected_line_update(session, &id)) {
         queue_connected_line_update(session, &id);
      }
   }
   ast_party_id_free(&id);
}

/*!
 * \internal
 * \brief Session supplement callback on an incoming INVITE request
 *
 * If we are receiving an initial INVITE, then we will set the session's identity
 * based on the INVITE or configured endpoint values. If we are receiving a reinvite,
 * then we will potentially queue a connected line update via the \ref update_incoming_connected_line
 * function
 *
 * \param session The session that has received an INVITE
 * \param rdata The incoming INVITE
 */
static int caller_id_incoming_request(struct ast_sip_session *session, pjsip_rx_data *rdata)
{
   if (!session->channel) {
      int ani2;
      /*
       * Since we have no channel this must be the initial inbound
       * INVITE.  Set the session ID directly because the channel
       * has not been created yet.
       */

      if (session->endpoint->id.trust_inbound
         && (!set_id_from_pai(rdata, &session->id)
            || !set_id_from_rpid(rdata, &session->id))) {
         ast_free(session->id.tag);
         session->id.tag = ast_strdup(session->endpoint->id.self.tag);
         return 0;
      }
      ast_party_id_copy(&session->id, &session->endpoint->id.self);
      if (!session->endpoint->id.self.number.valid) {
         set_id_from_from(rdata, &session->id);
      }
      if (!set_id_from_oli(rdata, &ani2)) {
         session->ani2 = 0;
      }
   } else {
      /*
       * ReINVITE or UPDATE.  Check for changes to the ID and queue
       * a connected line update if necessary.
       */
      update_incoming_connected_line(session, rdata);
   }
   return 0;
}

/*!
 * \internal
 * \brief Session supplement callback on INVITE response
 *
 * INVITE responses could result in queuing connected line updates.
 *
 * \param session The session on which communication is happening
 * \param rdata The incoming INVITE response
 */
static void caller_id_incoming_response(struct ast_sip_session *session, pjsip_rx_data *rdata)
{
   if (!session->channel) {
      return;
   }

   update_incoming_connected_line(session, rdata);
}

/*!
 * \internal
 * \brief Create an identity header for an outgoing message
 * \param hdr_name The name of the header to create
 * \param tdata The message to place the header on
 * \param id The identification information for the new header
 * \return newly-created header
 */
static pjsip_fromto_hdr *create_new_id_hdr(const pj_str_t *hdr_name, pjsip_fromto_hdr *base, pjsip_tx_data *tdata, const struct ast_party_id *id)
{
   pjsip_fromto_hdr *id_hdr;
   pjsip_name_addr *id_name_addr;
   pjsip_sip_uri *id_uri;

   id_hdr = pjsip_from_hdr_create(tdata->pool);
   id_hdr->type = PJSIP_H_OTHER;
   id_hdr->sname = id_hdr->name = *hdr_name;

   id_name_addr = pjsip_uri_clone(tdata->pool, base->uri);
   id_uri = pjsip_uri_get_uri(id_name_addr->uri);

   if (id->name.valid && !ast_strlen_zero(id->name.str)) {
      int name_buf_len = strlen(id->name.str) * 2 + 1;
      char *name_buf = ast_alloca(name_buf_len);

      ast_escape_quoted(id->name.str, name_buf, name_buf_len);
      pj_strdup2(tdata->pool, &id_name_addr->display, name_buf);
   } else {
      /*
       * We need to clear the remnants of the clone or it'll be left set.
       * pj_strdup2 is safe to call with a NULL src and it resets both slen and ptr.
       */
      pj_strdup2(tdata->pool, &id_name_addr->display, NULL);
   }

   if (id->number.valid) {
      pj_strdup2(tdata->pool, &id_uri->user, id->number.str);
   } else {
      /* Similar to name, make sure the number is also cleared when invalid */
      pj_strdup2(tdata->pool, &id_uri->user, NULL);
   }

   id_hdr->uri = (pjsip_uri *) id_name_addr;
   return id_hdr;
}

/*!
 * \internal
 * \brief Add a Privacy header to an outbound message
 *
 * When sending a P-Asserted-Identity header, if privacy is requested, then we
 * will need to indicate such by adding a Privacy header. Similarly, if no
 * privacy is requested, and a Privacy header already exists on the message,
 * then the old Privacy header should be removed.
 *
 * \param tdata The outbound message to add the Privacy header to
 * \param id The id information used to determine privacy
 */
static void add_privacy_header(pjsip_tx_data *tdata, const struct ast_party_id *id)
{
   static const pj_str_t pj_privacy_name = { "Privacy", 7 };
   static const pj_str_t pj_privacy_value = { "id", 2 };
   pjsip_hdr *old_privacy;

   old_privacy = pjsip_msg_find_hdr_by_name(tdata->msg, &pj_privacy_name, NULL);

   if ((ast_party_id_presentation(id) & AST_PRES_RESTRICTION) == AST_PRES_ALLOWED) {
      if (old_privacy) {
         pj_list_erase(old_privacy);
      }
   } else if (!old_privacy) {
      pjsip_generic_string_hdr *privacy_hdr = pjsip_generic_string_hdr_create(
            tdata->pool, &pj_privacy_name, &pj_privacy_value);
      pjsip_msg_add_hdr(tdata->msg, (pjsip_hdr *)privacy_hdr);
   }
}

/*!
 * \internal
 * \brief Add a P-Asserted-Identity header to an outbound message
 * \param tdata The message to add the header to
 * \param id The identification information used to populate the header
 */
static void add_pai_header(const struct ast_sip_session *session, pjsip_tx_data *tdata, const struct ast_party_id *id)
{
   static const pj_str_t pj_pai_name = { "P-Asserted-Identity", 19 };
   pjsip_fromto_hdr *base;
   pjsip_fromto_hdr *pai_hdr;
   pjsip_fromto_hdr *old_pai;

   /* Since inv_session reuses responses, we have to make sure there's not already
    * a P-Asserted-Identity present. If there is, we just modify the old one.
    */
   old_pai = pjsip_msg_find_hdr_by_name(tdata->msg, &pj_pai_name, NULL);
   if (old_pai) {
      /* If type is OTHER, then the existing header was most likely
       * added by the PJSIP_HEADER dial plan function as a simple
       * name/value pair.  We can't pass this to modify_id_header because
       * there are no virtual functions to get the uri.  We could parse
       * it into a pjsip_fromto_hdr but it isn't worth it since
       * modify_id_header is just going to overwrite the name and number
       * anyway.  We'll just remove it from the header list instead
       * and create a new one.
       */
      if (old_pai->type == PJSIP_H_OTHER) {
         pj_list_erase(old_pai);
      } else {
         ast_sip_modify_id_header(tdata->pool, old_pai, id);
         add_privacy_header(tdata, id);
         return;
      }
   }

   if (tdata->msg->type == PJSIP_REQUEST_MSG) {
      base = session->saved_from_hdr ? session->saved_from_hdr : PJSIP_MSG_FROM_HDR(tdata->msg);
   } else {
      base = PJSIP_MSG_TO_HDR(tdata->msg);
   }

   pai_hdr = create_new_id_hdr(&pj_pai_name, base, tdata, id);
   if (!pai_hdr) {
      return;
   }
   add_privacy_header(tdata, id);

   pjsip_msg_add_hdr(tdata->msg, (pjsip_hdr *)pai_hdr);
}

/*!
 * \internal
 * \brief Add party parameter to a Remote-Party-ID header.
 *
 * \param tdata The message where the Remote-Party-ID header is
 * \param hdr The header on which the parameters are being added
 * \param session The session involved
 */
static void add_party_param(pjsip_tx_data *tdata, pjsip_fromto_hdr *hdr, const struct ast_sip_session *session)
{
   static const pj_str_t party_str = { "party", 5 };
   static const pj_str_t calling_str = { "calling", 7 };
   static const pj_str_t called_str = { "called", 6 };
   pjsip_param *party;

   /* The party value can't change throughout the lifetime, so it is set only once */
   party = pjsip_param_find(&hdr->other_param, &party_str);
   if (party) {
      return;
   }

   party = PJ_POOL_ALLOC_T(tdata->pool, pjsip_param);
   party->name = party_str;
   party->value = (session->inv_session->role == PJSIP_ROLE_UAC) ? calling_str : called_str;
   pj_list_insert_before(&hdr->other_param, party);
}

/*!
 * \internal
 * \brief Add privacy and screen parameters to a Remote-Party-ID header.
 *
 * If privacy is requested, then the privacy and screen parameters need to
 * reflect this. Similarly, if no privacy or screening is to be communicated,
 * we need to make sure that any previously set values are updated.
 *
 * \param tdata The message where the Remote-Party-ID header is
 * \param hdr The header on which the parameters are being added
 * \param id The identification information used to determine privacy
 */
static void add_privacy_params(pjsip_tx_data *tdata, pjsip_fromto_hdr *hdr, const struct ast_party_id *id)
{
   static const pj_str_t privacy_str = { "privacy", 7 };
   static const pj_str_t screen_str = { "screen", 6 };
   static const pj_str_t privacy_full_str = { "full", 4 };
   static const pj_str_t privacy_off_str = { "off", 3 };
   static const pj_str_t screen_yes_str = { "yes", 3 };
   static const pj_str_t screen_no_str = { "no", 2 };
   pjsip_param *old_privacy;
   pjsip_param *old_screen;
   pjsip_param *privacy;
   pjsip_param *screen;
   int presentation;

   old_privacy = pjsip_param_find(&hdr->other_param, &privacy_str);
   old_screen = pjsip_param_find(&hdr->other_param, &screen_str);

   if (!old_privacy) {
      privacy = PJ_POOL_ALLOC_T(tdata->pool, pjsip_param);
      privacy->name = privacy_str;
      pj_list_insert_before(&hdr->other_param, privacy);
   } else {
      privacy = old_privacy;
   }

   if (!old_screen) {
      screen = PJ_POOL_ALLOC_T(tdata->pool, pjsip_param);
      screen->name = screen_str;
      pj_list_insert_before(&hdr->other_param, screen);
   } else {
      screen = old_screen;
   }

   presentation = ast_party_id_presentation(id);
   if ((presentation & AST_PRES_RESTRICTION) == AST_PRES_ALLOWED) {
      privacy->value = privacy_off_str;
   } else {
      privacy->value = privacy_full_str;
   }
   if ((presentation & AST_PRES_NUMBER_TYPE) == AST_PRES_USER_NUMBER_PASSED_SCREEN) {
      screen->value = screen_yes_str;
   } else {
      screen->value = screen_no_str;
   }
}

/*!
 * \internal
 * \brief Add a Remote-Party-ID header to an outbound message
 * \param tdata The message to add the header to
 * \param id The identification information used to populate the header
 */
static void add_rpid_header(const struct ast_sip_session *session, pjsip_tx_data *tdata, const struct ast_party_id *id)
{
   static const pj_str_t pj_rpid_name = { "Remote-Party-ID", 15 };
   pjsip_fromto_hdr *base;
   pjsip_fromto_hdr *rpid_hdr;
   pjsip_fromto_hdr *old_rpid;

   /* Since inv_session reuses responses, we have to make sure there's not already
    * a P-Asserted-Identity present. If there is, we just modify the old one.
    */
   old_rpid = pjsip_msg_find_hdr_by_name(tdata->msg, &pj_rpid_name, NULL);
   if (old_rpid) {
      /* If type is OTHER, then the existing header was most likely
       * added by the PJSIP_HEADER dial plan function as a simple
       * name/value pair.  We can't pass this to modify_id_header because
       * there are no virtual functions to get the uri.  We could parse
       * it into a pjsip_fromto_hdr but it isn't worth it since
       * modify_id_header is just going to overwrite the name and number
       * anyway.  We'll just remove it from the header list instead
       * and create a new one.
       */
      if (old_rpid->type == PJSIP_H_OTHER) {
         pj_list_erase(old_rpid);
      } else {
         ast_sip_modify_id_header(tdata->pool, old_rpid, id);
         add_party_param(tdata, old_rpid, session);
         add_privacy_params(tdata, old_rpid, id);
         return;
      }
   }

   if (tdata->msg->type == PJSIP_REQUEST_MSG) {
      base = session->saved_from_hdr ? session->saved_from_hdr : PJSIP_MSG_FROM_HDR(tdata->msg);
   } else {
      base = PJSIP_MSG_TO_HDR(tdata->msg);
   }

   rpid_hdr = create_new_id_hdr(&pj_rpid_name, base, tdata, id);
   if (!rpid_hdr) {
      return;
   }
   add_party_param(tdata, rpid_hdr, session);
   add_privacy_params(tdata, rpid_hdr, id);
   pjsip_msg_add_hdr(tdata->msg, (pjsip_hdr *)rpid_hdr);
}

/*!
 * \internal
 * \brief Add any appropriate identification headers to an outbound SIP message
 *
 * This will determine if an outbound message should have identification headers and
 * will add the appropriately configured headers
 *
 * \param session The session on which we will be sending the message
 * \param tdata The outbound message
 * \param The identity information to place on the message
 */
static void add_id_headers(const struct ast_sip_session *session, pjsip_tx_data *tdata, const struct ast_party_id *id)
{
   if (!id->number.valid
      || (!session->endpoint->id.trust_outbound
         && (ast_party_id_presentation(id) & AST_PRES_RESTRICTION) != AST_PRES_ALLOWED)) {
      return;
   }
   if (session->endpoint->id.send_pai) {
      add_pai_header(session, tdata, id);
   }
   if (session->endpoint->id.send_rpid) {
      add_rpid_header(session, tdata, id);
   }
}

/*!
 * \internal
 * \brief Session supplement callback for outgoing INVITE requests
 *
 * On all INVITEs (initial and reinvite) we may add other identity headers
 * such as P-Asserted-Identity and Remote-Party-ID based on configuration
 * and privacy settings
 *
 * \param session The session on which the INVITE will be sent
 * \param tdata The outbound INVITE request
 */
static void caller_id_outgoing_request(struct ast_sip_session *session, pjsip_tx_data *tdata)
{
   struct ast_party_id effective_id;
   struct ast_party_id connected_id;

   if (!session->channel) {
      return;
   }

   ast_party_id_init(&connected_id);
   ast_channel_lock(session->channel);
   effective_id = ast_channel_connected_effective_id(session->channel);
   ast_party_id_copy(&connected_id, &effective_id);
   ast_channel_unlock(session->channel);

   add_id_headers(session, tdata, &connected_id);
   ast_party_id_free(&connected_id);
}

/*!
 * \internal
 * \brief Session supplement for outgoing INVITE response
 *
 * This will add P-Asserted-Identity and Remote-Party-ID headers if necessary
 *
 * \param session The session on which the INVITE response is to be sent
 * \param tdata The outbound INVITE response
 */
static void caller_id_outgoing_response(struct ast_sip_session *session, pjsip_tx_data *tdata)
{
   struct ast_party_id effective_id;
   struct ast_party_id connected_id;

   if (!session->channel
      || (!session->endpoint->id.send_connected_line
         && session->inv_session
         && session->inv_session->state >= PJSIP_INV_STATE_EARLY)) {
      return;
   }

   /* Must do a deep copy unless we hold the channel lock the entire time. */
   ast_party_id_init(&connected_id);
   ast_channel_lock(session->channel);
   effective_id = ast_channel_connected_effective_id(session->channel);
   ast_party_id_copy(&connected_id, &effective_id);
   ast_channel_unlock(session->channel);

   add_id_headers(session, tdata, &connected_id);
   ast_party_id_free(&connected_id);
}

static struct ast_sip_session_supplement caller_id_supplement = {
   .method = "INVITE,UPDATE",
   .priority = AST_SIP_SUPPLEMENT_PRIORITY_CHANNEL - 1000,
   .incoming_request = caller_id_incoming_request,
   .incoming_response = caller_id_incoming_response,
   .outgoing_request = caller_id_outgoing_request,
   .outgoing_response = caller_id_outgoing_response,
};

static int load_module(void)
{
   ast_module_shutdown_ref(AST_MODULE_SELF);
   ast_sip_session_register_supplement(&caller_id_supplement);
   return AST_MODULE_LOAD_SUCCESS;
}

static int unload_module(void)
{
   ast_sip_session_unregister_supplement(&caller_id_supplement);
   return 0;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP Caller ID 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",
);