Add PJSIP_HEADER function for manipulation of SIP headers in the PJSIP stack
authorMatthew Jordan <mjordan@digium.com>
Tue, 8 Oct 2013 22:59:32 +0000 (22:59 +0000)
committerMatthew Jordan <mjordan@digium.com>
Tue, 8 Oct 2013 22:59:32 +0000 (22:59 +0000)
This patch adds support to the PJSIP stack in Asterisk for SIP header
manipulation. Note that this is analagous to SIPAddHeader/SIPRemoveHeader.

For PJSIP_HEADER, an incoming supplemental session callback is registered that
takes the pjsip_hdrs from the incoming session and stores them in a linked
list in the session datastore.  Calls to PJSIP_HEADER traverse over the list
and return the nth matching header where 'n' is the 'number' argument to the
function.

When adding a header, the first call creates a datastore and linked list and
adds the datastore to the session.  The header is then created as a pjsip_hdr
and added to the list.  An outgoing supplemental session callback then
traverses the list and adds the headers to the outgoing pjsip_msg.

When removing a header, the list created with PJSIP_HEADER(add,...) is
traversed and all matching entries are removed.

(closes issue ASTERISK-22498)
Reported by: George Joseph
patch:
  res_pjsip_header_funcs_v1.patch uploaded by george.joseph (License 6322)
........

Merged revisions 400771 from http://svn.asterisk.org/svn/asterisk/branches/12

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@400772 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_pjsip_header_funcs.c [new file with mode: 0644]

diff --git a/res/res_pjsip_header_funcs.c b/res/res_pjsip_header_funcs.c
new file mode 100644 (file)
index 0000000..90ca074
--- /dev/null
@@ -0,0 +1,609 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2013, Fairview 5 Engineering, LLC
+ *
+ * George Joseph <george.joseph@fairview5.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/channel.h"
+#include "asterisk/pbx.h"
+#include "asterisk/app.h"
+#include "asterisk/module.h"
+#include "asterisk/utils.h"
+
+/*** DOCUMENTATION
+       <function name="PJSIP_HEADER" language="en_US">
+               <synopsis>
+                       Gets, adds, updates or removes the specified SIP header from a PJSIP session.
+               </synopsis>
+               <syntax>
+                       <parameter name="action" required="true">
+                               <enumlist>
+                                       <enum name="read"><para>Returns instance <replaceable>number</replaceable>
+                                       of header <replaceable>name</replaceable>.</para></enum>
+
+                                       <enum name="add"><para>Adds a new header <replaceable>name</replaceable>
+                                       to this session.</para></enum>
+
+                                       <enum name="update"><para>Updates instance <replaceable>number</replaceable>
+                                       of header <replaceable>name</replaceable> to a new value.
+                                       The header must already exist.</para></enum>
+
+                                       <enum name="remove"><para>Removes all instances of previously added headers
+                                       whose names match <replaceable>name</replaceable>. A <literal>*</literal>
+                                       may be appended to <replaceable>name</replaceable> to remove all headers
+                                       <emphasis>beginning with</emphasis> <replaceable>name</replaceable>.
+                                       <replaceable>name</replaceable> may be set to a single <literal>*</literal>
+                                       to clear <emphasis>all</emphasis> previously added headers. In all cases,
+                                       the number of headers actually removed is returned.</para></enum>
+                               </enumlist>
+                       </parameter>
+
+                       <parameter name="name" required="true"><para>The name of the header.</para></parameter>
+
+                       <parameter name="number" required="false">
+                               <para>If there's more than 1 header with the same name, this specifies which header
+                               to read or update.  If not specified, defaults to <literal>1</literal> meaning
+                               the first matching header.  Not valid for <literal>add</literal> or
+                               <literal>remove</literal>.</para>
+                       </parameter>
+
+               </syntax>
+               <description>
+                       <para>Examples:</para>
+                       <para>;</para>
+                       <para>; Set 'somevar' to the value of the 'From' header.</para>
+                       <para>exten => 1,1,Set(somevar=${PJSIP_HEADER(read,From)})</para>
+                       <para>;</para>
+                       <para>; Set 'via2' to the value of the 2nd 'Via' header.</para>
+                       <para>exten => 1,1,Set(via2=${PJSIP_HEADER(read,Via,2)})</para>
+                       <para>;</para>
+                       <para>; Add an 'X-Myheader' header with the value of 'myvalue'.</para>
+                       <para>exten => 1,1,Set(PJSIP_HEADER(add,X-MyHeader)=myvalue)</para>
+                       <para>;</para>
+                       <para>; Add an 'X-Myheader' header with an empty value.</para>
+                       <para>exten => 1,1,Set(PJSIP_HEADER(add,X-MyHeader)=)</para>
+                       <para>;</para>
+                       <para>; Update the value of the header named 'X-Myheader' to 'newvalue'.</para>
+                       <para>; 'X-Myheader' must already exist or the call will fail.</para>
+                       <para>exten => 1,1,Set(PJSIP_HEADER(update,X-MyHeader)=newvalue)</para>
+                       <para>;</para>
+                       <para>; Remove all headers whose names exactly match 'X-MyHeader'.</para>
+                       <para>exten => 1,1,Set(PJSIP_HEADER(remove,X-MyHeader)=)</para>
+                       <para>;</para>
+                       <para>; Remove all headers that begin with 'X-My'.</para>
+                       <para>exten => 1,1,Set(PJSIP_HEADER(remove,X-My*)=)</para>
+                       <para>;</para>
+                       <para>; Remove all previously added headers.</para>
+                       <para>exten => 1,1,Set(PJSIP_HEADER(remove,*)=)</para>
+                       <para>;</para>
+
+                       <note><para>The <literal>remove</literal> action can be called by reading
+                       <emphasis>or</emphasis> writing PJSIP_HEADER.</para>
+                       <para>;</para>
+                       <para>; Display the number of headers removed</para>
+                       <para>exten => 1,1,Verbose( Removed ${PJSIP_HEADER(remove,X-MyHeader)} headers)</para>
+                       <para>;</para>
+                       <para>; Set a variable to the number of headers removed</para>
+                       <para>exten => 1,1,Set(count=${PJSIP_HEADER(remove,X-MyHeader)})</para>
+                       <para>;</para>
+                       <para>; Just remove them ignoring any count</para>
+                       <para>exten => 1,1,Set(=${PJSIP_HEADER(remove,X-MyHeader)})</para>
+                       <para>exten => 1,1,Set(PJSIP_HEADER(remove,X-MyHeader)=)</para>
+                       <para>;</para>
+                       </note>
+
+                       <note><para>If you call PJSIP_HEADER in a normal dialplan context you'll be
+                       operating on the <emphasis>caller's (incoming)</emphasis> channel which
+                       may not be what you want.  To operate on the <emphasis>callee's (outgoing)</emphasis>
+                       channel call PJSIP_HEADER in a pre-dial handler. </para>
+                       <para>Example:</para>
+                       <para>;</para>
+                       <para>[handler]</para>
+                       <para>exten => addheader,1,Set(PJSIP_HEADER(add,X-MyHeader)=myvalue)</para>
+                       <para>exten => addheader,2,Set(PJSIP_HEADER(add,X-MyHeader2)=myvalue2)</para>
+                       <para>;</para>
+                       <para>[somecontext]</para>
+                       <para>exten => 1,1,Dial(PJSIP/${EXTEN},,b(handler^addheader^1))</para>
+                       <para>;</para>
+                       </note>
+               </description>
+       </function>
+ ***/
+
+/*! \brief Linked list for accumulating headers */
+struct hdr_list_entry {
+       pjsip_hdr *hdr;
+       AST_LIST_ENTRY(hdr_list_entry) nextptr;
+};
+AST_LIST_HEAD(hdr_list, hdr_list_entry);
+
+/*! \brief Destructor for hdr_list */
+static void hdr_list_destroy(void *obj)
+{
+       AST_LIST_HEAD_DESTROY((struct hdr_list *) obj);
+}
+
+/*! \brief Datastore for saving headers */
+static const struct ast_datastore_info header_datastore = {
+       .type = "header_datastore",
+       .destroy = hdr_list_destroy,
+};
+
+/*! \brief Data structure used for ast_sip_push_task_synchronous  */
+struct header_data {
+       struct ast_sip_channel_pvt *channel;
+       char *header_name;
+       const char *header_value;
+       char *buf;
+       int header_number;
+       size_t len;
+};
+
+/*!
+ * \internal
+ * \brief Insert the header pointers into the linked list.
+ *
+ * For each header in the message, allocate a list entry,
+ * clone the header, then insert the entry.
+ */
+static int insert_headers(pj_pool_t * pool, struct hdr_list *list, pjsip_msg * msg)
+{
+       pjsip_hdr *hdr = msg->hdr.next;
+       struct hdr_list_entry *le;
+
+       while (hdr && hdr != &msg->hdr) {
+               le = pj_pool_zalloc(pool, sizeof(struct hdr_list_entry));
+               le->hdr = pjsip_hdr_clone(pool, hdr);
+               AST_LIST_INSERT_TAIL(list, le, nextptr);
+               hdr = hdr->next;
+       }
+
+       return 0;
+}
+
+/*!
+ * \internal
+ * \brief Session supplement callback on an incoming INVITE request
+ *
+ * Retrieve the header_datastore from the session or create one if it doesn't exist.
+ * Create and initialize the list if needed.
+ * Insert the headers.
+ */
+static int incoming_request(struct ast_sip_session *session, pjsip_rx_data * rdata)
+{
+       pj_pool_t *pool = session->inv_session->dlg->pool;
+       RAII_VAR(struct ast_datastore *, datastore,
+                        ast_sip_session_get_datastore(session, header_datastore.type), ao2_cleanup);
+
+       if (!datastore) {
+               if (!(datastore =
+                         ast_sip_session_alloc_datastore(&header_datastore, header_datastore.type))
+                       ||
+                       !(datastore->data = pj_pool_alloc(pool, sizeof(struct hdr_list))) ||
+                       ast_sip_session_add_datastore(session, datastore)) {
+                       ast_log(AST_LOG_ERROR, "Unable to create datastore for header functions.\n");
+                       return 0;
+               }
+               AST_LIST_HEAD_INIT((struct hdr_list *) datastore->data);
+       }
+       insert_headers(pool, (struct hdr_list *) datastore->data, rdata->msg_info.msg);
+
+       return 0;
+}
+
+/*!
+ * \internal
+ * \brief Search list for nth occurrence of specific header.
+ */
+static pjsip_hdr *find_header(struct hdr_list *list, const char *header_name,
+                                                         int header_number)
+{
+       struct hdr_list_entry *le;
+       pjsip_hdr *hdr = NULL;
+       int i = 1;
+
+       if (!list || ast_strlen_zero(header_name) || header_number < 1) {
+               return NULL;
+       }
+
+       AST_LIST_TRAVERSE(list, le, nextptr) {
+               if (pj_stricmp2(&le->hdr->name, header_name) == 0 && i++ == header_number) {
+                       hdr = le->hdr;
+                       break;
+               }
+       }
+
+       return hdr;
+}
+
+
+/*!
+ * \internal
+ * \brief Implements PJSIP_HEADER 'read' by searching the for the requested header.
+ *
+ * Retrieve the header_datastore.
+ * Search for the nth matching header.
+ * Validate the pjsip_hdr found.
+ * Parse pjsip_hdr into a name and value.
+ * Return the value.
+ */
+static int read_header(void *obj)
+{
+       struct header_data *data = obj;
+       pjsip_hdr *hdr = NULL;
+       char *pj_hdr_string;
+       size_t pj_hdr_string_len;
+       char *p;
+       size_t plen;
+       RAII_VAR(struct ast_datastore *, datastore,
+                        ast_sip_session_get_datastore(data->channel->session, header_datastore.type),
+                        ao2_cleanup);
+
+       if (!datastore || !datastore->data) {
+               ast_debug(1, "There was no datastore from which to read headers.\n");
+               return -1;
+       }
+
+       hdr = find_header((struct hdr_list *) datastore->data, data->header_name,
+                                         data->header_number);
+
+       if (!hdr) {
+               ast_debug(1, "There was no header named %s.\n", data->header_name);
+               return -1;
+       }
+
+       pj_hdr_string = ast_alloca(data->len);
+       pj_hdr_string_len = pjsip_hdr_print_on(hdr, pj_hdr_string, data->len);
+       pj_hdr_string[pj_hdr_string_len] = '\0';
+
+       p = strchr(pj_hdr_string, ':');
+       if (!p) {
+               ast_log(AST_LOG_ERROR,
+                               "A malformed header was returned from pjsip_hdr_print_on.\n");
+               return -1;
+       }
+
+       ++p;
+       p = ast_strip(p);
+       plen = strlen(p);
+       if (plen + 1 > data->len) {
+               ast_log(AST_LOG_ERROR,
+                               "Buffer isn't big enough to hold header value.  %lu > %lu\n", plen + 1,
+                               data->len);
+               return -1;
+       }
+
+       ast_copy_string(data->buf, p, data->len);
+
+       return 0;
+}
+
+/*!
+ * \internal
+ * \brief Implements PJSIP_HEADER 'add' by inserting the specified header into thge list.
+ *
+ * Retrieve the header_datastore from the session or create one if it doesn't exist.
+ * Create and initialize the list if needed.
+ * Create the pj_strs for name and value.
+ * Create pjsip_msg and hdr_list_entry.
+ * Add the entry to the list.
+ */
+static int add_header(void *obj)
+{
+       struct header_data *data = obj;
+       struct ast_sip_session *session = data->channel->session;
+       pj_pool_t *pool = session->inv_session->dlg->pool;
+       pj_str_t pj_header_name;
+       pj_str_t pj_header_value;
+       struct hdr_list_entry *le;
+       struct hdr_list *list;
+
+       RAII_VAR(struct ast_datastore *, datastore,
+                        ast_sip_session_get_datastore(session, header_datastore.type), ao2_cleanup);
+
+       if (!datastore) {
+               if (!(datastore = ast_sip_session_alloc_datastore(&header_datastore,
+                                                                                                                 header_datastore.type))
+                       || !(datastore->data = pj_pool_alloc(pool, sizeof(struct hdr_list)))
+                       || ast_sip_session_add_datastore(session, datastore)) {
+                       ast_log(AST_LOG_ERROR, "Unable to create datastore for header functions.\n");
+                       return -1;
+               }
+               AST_LIST_HEAD_INIT((struct hdr_list *) datastore->data);
+       }
+
+       ast_debug(1, "Adding header %s with value %s\n", data->header_name,
+                         data->header_value);
+
+       pj_cstr(&pj_header_name, data->header_name);
+       pj_cstr(&pj_header_value, data->header_value);
+       le = pj_pool_zalloc(pool, sizeof(struct hdr_list_entry));
+       le->hdr = (pjsip_hdr *) pjsip_generic_string_hdr_create(pool, &pj_header_name,
+                                                                                                                       &pj_header_value);
+       list = datastore->data;
+
+       AST_LIST_INSERT_TAIL(list, le, nextptr);
+
+       return 0;
+}
+
+/*!
+ * \internal
+ * \brief Implements PJSIP_HEADER 'update' by finding the specified header and updating it.
+ *
+ * Retrieve the header_datastore from the session or create one if it doesn't exist.
+ * Create and initialize the list if needed.
+ * Create the pj_strs for name and value.
+ * Create pjsip_msg and hdr_list_entry.
+ * Add the entry to the list.
+ */
+static int update_header(void *obj)
+{
+       struct header_data *data = obj;
+       pjsip_hdr *hdr = NULL;
+       RAII_VAR(struct ast_datastore *, datastore,
+                        ast_sip_session_get_datastore(data->channel->session, header_datastore.type),
+                        ao2_cleanup);
+
+       if (!datastore || !datastore->data) {
+               ast_log(AST_LOG_ERROR, "No headers had been previously added to this session.\n");
+               return -1;
+       }
+
+       hdr = find_header((struct hdr_list *) datastore->data, data->header_name,
+                                         data->header_number);
+
+       if (!hdr) {
+               ast_log(AST_LOG_ERROR, "There was no header named %s.\n", data->header_name);
+               return -1;
+       }
+
+       pj_strcpy2(&((pjsip_generic_string_hdr *) hdr)->hvalue, data->header_value);
+
+       return 0;
+}
+
+/*!
+ * \internal
+ * \brief Implements PJSIP_HEADER 'remove' by finding the specified header and removing it.
+ *
+ * Retrieve the header_datastore from the session.  Fail if it doesn't exist.
+ * If the header_name is exactly '*', the entire list is simply destroyed.
+ * Otherwise search the list for the matching header name which may be a partial name.
+ */
+static int remove_header(void *obj)
+{
+       struct header_data *data = obj;
+       size_t len = strlen(data->header_name);
+       struct hdr_list *list;
+       struct hdr_list_entry *le;
+       int removed_count = 0;
+       RAII_VAR(struct ast_datastore *, datastore,
+                        ast_sip_session_get_datastore(data->channel->session, header_datastore.type),
+                        ao2_cleanup);
+
+       if (!datastore || !datastore->data) {
+               ast_log(AST_LOG_ERROR, "No headers had been previously added to this session.\n");
+               return -1;
+       }
+
+       list = datastore->data;
+       AST_LIST_TRAVERSE_SAFE_BEGIN(list, le, nextptr) {
+               if (data->header_name[len - 1] == '*') {
+                       if (pj_strnicmp2(&le->hdr->name, data->header_name, len - 1) == 0) {
+                               AST_LIST_REMOVE_CURRENT(nextptr);
+                               removed_count++;
+                       }
+               } else {
+                       if (pj_stricmp2(&le->hdr->name, data->header_name) == 0) {
+                               AST_LIST_REMOVE_CURRENT(nextptr);
+                               removed_count++;
+                       }
+               }
+       }
+       AST_LIST_TRAVERSE_SAFE_END;
+
+       if (data->buf && data->len) {
+               snprintf(data->buf, data->len, "%d", removed_count);
+       }
+
+       return 0;
+}
+
+/*!
+ * \brief Implements function 'read' callback.
+ *
+ * Valid actions are 'read' and 'remove'.
+ */
+static int func_read_header(struct ast_channel *chan, const char *function, char *data,
+                                                       char *buf, size_t len)
+{
+       struct ast_sip_channel_pvt *channel = ast_channel_tech_pvt(chan);
+       struct header_data header_data;
+       int number;
+       AST_DECLARE_APP_ARGS(args,
+                                                AST_APP_ARG(action);
+                                                AST_APP_ARG(header_name); AST_APP_ARG(header_number););
+       AST_STANDARD_APP_ARGS(args, data);
+
+       if (ast_strlen_zero(args.action)) {
+               ast_log(AST_LOG_ERROR, "This function requires an action.\n");
+               return -1;
+       }
+       if (ast_strlen_zero(args.header_name)) {
+               ast_log(AST_LOG_ERROR, "This function requires a header name.\n");
+               return -1;
+       }
+       if (!args.header_number) {
+               number = 1;
+       } else {
+               sscanf(args.header_number, "%30d", &number);
+               if (number < 1) {
+                       number = 1;
+               }
+       }
+
+       header_data.channel = channel;
+       header_data.header_name = args.header_name;
+       header_data.header_number = number;
+       header_data.header_value = NULL;
+       header_data.buf = buf;
+       header_data.len = len;
+
+       if (stricmp(args.action, "read") == 0) {
+               return ast_sip_push_task_synchronous(channel->session->serializer, read_header,
+                                                                                        &header_data);
+       } else if (stricmp(args.action, "remove") == 0) {
+               return ast_sip_push_task_synchronous(channel->session->serializer, remove_header,
+                                                                                        &header_data);
+       } else {
+               ast_log(AST_LOG_ERROR,
+                               "Unknown action \'%s\' is not valid,  Must be \'read\' or \'remove\'.\n",
+                               args.action);
+               return -1;
+       }
+}
+
+/*!
+ * \brief Implements function 'write' callback.
+ *
+ * Valid actions are 'add', 'update' and 'remove'.
+ */
+static int func_write_header(struct ast_channel *chan, const char *cmd, char *data,
+                                                        const char *value)
+{
+       struct ast_sip_channel_pvt *channel = ast_channel_tech_pvt(chan);
+       struct header_data header_data;
+       int header_number;
+       AST_DECLARE_APP_ARGS(args,
+                                                AST_APP_ARG(action);
+                                                AST_APP_ARG(header_name); AST_APP_ARG(header_number););
+       AST_STANDARD_APP_ARGS(args, data);
+
+       if (ast_strlen_zero(args.action)) {
+               ast_log(AST_LOG_ERROR, "This function requires an action.\n");
+               return -1;
+       }
+       if (ast_strlen_zero(args.header_name)) {
+               ast_log(AST_LOG_ERROR, "This function requires a header name.\n");
+               return -1;
+       }
+       if (!args.header_number) {
+               header_number = 1;
+       } else {
+               sscanf(args.header_number, "%30d", &header_number);
+               if (header_number < 1) {
+                       header_number = 1;
+               }
+       }
+
+       header_data.channel = channel;
+       header_data.header_name = args.header_name;
+       header_data.header_number = header_number;
+       header_data.header_value = value;
+       header_data.buf = NULL;
+       header_data.len = 0;
+
+       if (stricmp(args.action, "add") == 0) {
+               return ast_sip_push_task_synchronous(channel->session->serializer, add_header,
+                                                                                        &header_data);
+       } else if (stricmp(args.action, "update") == 0) {
+               return ast_sip_push_task_synchronous(channel->session->serializer, update_header,
+                                                                                        &header_data);
+       } else if (stricmp(args.action, "remove") == 0) {
+               return ast_sip_push_task_synchronous(channel->session->serializer, remove_header,
+                                                                                        &header_data);
+       } else {
+               ast_log(AST_LOG_ERROR,
+                               "Unknown action \'%s\' is not valid,  Must be \'add\', \'update\', or \'remove\'.\n",
+                               args.action);
+               return -1;
+       }
+}
+
+static struct ast_custom_function pjsip_header_function = {
+       .name = "PJSIP_HEADER",
+       .read = func_read_header,
+       .write = func_write_header,
+};
+
+/*!
+ * \internal
+ * \brief Session supplement callback for outgoing INVITE requests
+ *
+ * Retrieve the header_datastore from the session.
+ * Add each header in the list to the outgoing message.
+ *
+ * These pjsip_hdr structures will have been created by add_header.
+ * Because outgoing_request may be called more than once with the same header
+ * list (as in the case of an authentication exchange), each pjsip_hdr structure
+ * MUST be newly cloned for each outgoing message.
+ */
+static void outgoing_request(struct ast_sip_session *session, pjsip_tx_data * tdata)
+{
+       pj_pool_t *pool = session->inv_session->dlg->pool;
+       struct hdr_list *list;
+       struct hdr_list_entry *le;
+       RAII_VAR(struct ast_datastore *, datastore,
+                        ast_sip_session_get_datastore(session, header_datastore.type), ao2_cleanup);
+
+       if (!datastore || !datastore->data) {
+               return;
+       }
+
+       list = datastore->data;
+       AST_LIST_TRAVERSE(list, le, nextptr) {
+               pjsip_msg_add_hdr(tdata->msg, (pjsip_hdr *) pjsip_hdr_clone(pool, le->hdr));
+       }
+}
+
+static struct ast_sip_session_supplement header_funcs_supplement = {
+       .method = "INVITE",
+       .priority = AST_SIP_SESSION_SUPPLEMENT_PRIORITY_CHANNEL - 1000,
+       .incoming_request = incoming_request,
+       .outgoing_request = outgoing_request,
+};
+
+static int load_module(void)
+{
+       ast_sip_session_register_supplement(&header_funcs_supplement);
+       ast_custom_function_register(&pjsip_header_function);
+
+       return AST_MODULE_LOAD_SUCCESS;
+}
+
+static int unload_module(void)
+{
+       ast_custom_function_unregister(&pjsip_header_function);
+       ast_sip_session_unregister_supplement(&header_funcs_supplement);
+       return 0;
+}
+
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP Header Functions",.load =
+                               load_module,.unload = unload_module,.load_pri = AST_MODPRI_APP_DEPEND,);