The large GULP->PJSIP renaming effort.

The general gist is to have a clear boundary between old SIP stuff
and new SIP stuff by having the word "SIP" for old stuff and "PJSIP"
for new stuff. Here's a brief rundown of the changes:

* The word "Gulp" in dialstrings, functions, and CLI commands is now
  "PJSIP"
* chan_gulp.c is now chan_pjsip.c
* Function names in chan_gulp.c that were "gulp_*" are now "chan_pjsip_*"
* All files that were "res_sip*" are now "res_pjsip*"
* The "res_sip" directory is now "res_pjsip"
* Files in the "res_pjsip" directory that began with "sip_*" are now "pjsip_*"
* The configuration file is now "pjsip.conf" instead of "res_sip.conf"
* The module info for all PJSIP-related files now uses "PJSIP" instead of "SIP"
* CLI and AMI commands created by Asterisk's PJSIP modules now have "pjsip" as
the starting word instead of "sip"



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@395764 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 2132 insertions, 0 deletions

diff --git a/res/res_pjsip_session.c b/res/res_pjsip_session.c
new file mode 100644
index 000000000..fd136082d
--- /dev/null
+++ b/res/res_pjsip_session.c
@@ -0,0 +1,2132 @@
+/*
+* Asterisk -- An open source telephony toolkit.
+*
+* Copyright (C) 2013, Digium, Inc.
+*
+* Mark Michelson <mmichelson@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>
+	<support_level>core</support_level>
+ ***/
+
+#include "asterisk.h"
+
+#include <pjsip.h>
+#include <pjsip_ua.h>
+#include <pjlib.h>
+
+#include "asterisk/res_pjsip.h"
+#include "asterisk/res_pjsip_session.h"
+#include "asterisk/datastore.h"
+#include "asterisk/module.h"
+#include "asterisk/logger.h"
+#include "asterisk/res_pjsip.h"
+#include "asterisk/astobj2.h"
+#include "asterisk/lock.h"
+#include "asterisk/uuid.h"
+#include "asterisk/pbx.h"
+#include "asterisk/taskprocessor.h"
+#include "asterisk/causes.h"
+#include "asterisk/sdp_srtp.h"
+#include "asterisk/dsp.h"
+
+#define SDP_HANDLER_BUCKETS 11
+
+/* Some forward declarations */
+static void handle_incoming_request(struct ast_sip_session *session, pjsip_rx_data *rdata);
+static void handle_incoming_response(struct ast_sip_session *session, pjsip_rx_data *rdata);
+static int handle_incoming(struct ast_sip_session *session, pjsip_rx_data *rdata);
+static void handle_outgoing_request(struct ast_sip_session *session, pjsip_tx_data *tdata);
+static void handle_outgoing_response(struct ast_sip_session *session, pjsip_tx_data *tdata);
+static void handle_outgoing(struct ast_sip_session *session, pjsip_tx_data *tdata);
+
+/*! \brief NAT hook for modifying outgoing messages with SDP */
+static struct ast_sip_nat_hook *nat_hook;
+
+/*!
+ * \brief Registered SDP stream handlers
+ *
+ * This container is keyed on stream types. Each
+ * object in the container is a linked list of
+ * handlers for the stream type.
+ */
+static struct ao2_container *sdp_handlers;
+
+/*!
+ * These are the objects in the sdp_handlers container
+ */
+struct sdp_handler_list {
+	/* The list of handlers to visit */
+	AST_LIST_HEAD_NOLOCK(, ast_sip_session_sdp_handler) list;
+	/* The handlers in this list handle streams of this type */
+	char stream_type[1];
+};
+
+static struct pjmedia_sdp_session *create_local_sdp(pjsip_inv_session *inv, struct ast_sip_session *session, const pjmedia_sdp_session *offer);
+
+static int sdp_handler_list_hash(const void *obj, int flags)
+{
+	const struct sdp_handler_list *handler_list = obj;
+	const char *stream_type = flags & OBJ_KEY ? obj : handler_list->stream_type;
+
+	return ast_str_hash(stream_type);
+}
+
+static int sdp_handler_list_cmp(void *obj, void *arg, int flags)
+{
+	struct sdp_handler_list *handler_list1 = obj;
+	struct sdp_handler_list *handler_list2 = arg;
+	const char *stream_type2 = flags & OBJ_KEY ? arg : handler_list2->stream_type;
+
+	return strcmp(handler_list1->stream_type, stream_type2) ? 0 : CMP_MATCH | CMP_STOP;
+}
+
+static int session_media_hash(const void *obj, int flags)
+{
+	const struct ast_sip_session_media *session_media = obj;
+	const char *stream_type = flags & OBJ_KEY ? obj : session_media->stream_type;
+
+	return ast_str_hash(stream_type);
+}
+
+static int session_media_cmp(void *obj, void *arg, int flags)
+{
+	struct ast_sip_session_media *session_media1 = obj;
+	struct ast_sip_session_media *session_media2 = arg;
+	const char *stream_type2 = flags & OBJ_KEY ? arg : session_media2->stream_type;
+
+	return strcmp(session_media1->stream_type, stream_type2) ? 0 : CMP_MATCH | CMP_STOP;
+}
+
+int ast_sip_session_register_sdp_handler(struct ast_sip_session_sdp_handler *handler, const char *stream_type)
+{
+	RAII_VAR(struct sdp_handler_list *, handler_list,
+			ao2_find(sdp_handlers, stream_type, OBJ_KEY), ao2_cleanup);
+	SCOPED_AO2LOCK(lock, sdp_handlers);
+
+	if (handler_list) {
+		struct ast_sip_session_sdp_handler *iter;
+		/* Check if this handler is already registered for this stream type */
+		AST_LIST_TRAVERSE(&handler_list->list, iter, next) {
+			if (!strcmp(iter->id, handler->id)) {
+				ast_log(LOG_WARNING, "Handler '%s' already registered for stream type '%s'.\n", handler->id, stream_type);
+				return -1;
+			}
+		}
+		AST_LIST_INSERT_TAIL(&handler_list->list, handler, next);
+		ast_debug(1, "Registered SDP stream handler '%s' for stream type '%s'\n", handler->id, stream_type); 
+		ast_module_ref(ast_module_info->self);
+		return 0;
+	}
+
+	/* No stream of this type has been registered yet, so we need to create a new list */
+	handler_list = ao2_alloc(sizeof(*handler_list) + strlen(stream_type), NULL);
+	if (!handler_list) {
+		return -1;
+	}
+	/* Safe use of strcpy */
+	strcpy(handler_list->stream_type, stream_type);
+	AST_LIST_HEAD_INIT_NOLOCK(&handler_list->list);
+	AST_LIST_INSERT_TAIL(&handler_list->list, handler, next);
+	if (!ao2_link(sdp_handlers, handler_list)) {
+		return -1;
+	}
+	ast_debug(1, "Registered SDP stream handler '%s' for stream type '%s'\n", handler->id, stream_type); 
+	ast_module_ref(ast_module_info->self);
+	return 0;
+}
+
+static int remove_handler(void *obj, void *arg, void *data, int flags)
+{
+	struct sdp_handler_list *handler_list = obj;
+	struct ast_sip_session_sdp_handler *handler = data;
+	struct ast_sip_session_sdp_handler *iter;
+	const char *stream_type = arg;
+
+	AST_LIST_TRAVERSE_SAFE_BEGIN(&handler_list->list, iter, next) {
+		if (!strcmp(iter->id, handler->id)) {
+			AST_LIST_REMOVE_CURRENT(next);
+			ast_debug(1, "Unregistered SDP stream handler '%s' for stream type '%s'\n", handler->id, stream_type);
+			ast_module_unref(ast_module_info->self);
+		}
+	}
+	AST_LIST_TRAVERSE_SAFE_END;
+
+	if (AST_LIST_EMPTY(&handler_list->list)) {
+		ast_debug(3, "No more handlers exist for stream type '%s'\n", stream_type);
+		return CMP_MATCH;
+	} else {
+		return CMP_STOP;
+	}
+}
+
+void ast_sip_session_unregister_sdp_handler(struct ast_sip_session_sdp_handler *handler, const char *stream_type)
+{
+	ao2_callback_data(sdp_handlers, OBJ_KEY | OBJ_UNLINK | OBJ_NODATA, remove_handler, (void *)stream_type, handler);
+}
+
+static int validate_port_hash(const void *obj, int flags)
+{
+	const int *port = obj;
+	return *port;
+}
+
+static int validate_port_cmp(void *obj, void *arg, int flags)
+{
+	int *port1 = obj;
+	int *port2 = arg;
+
+	return *port1 == *port2 ? CMP_MATCH | CMP_STOP : 0;
+}
+
+struct bundle_assoc {
+	int port;
+	char tag[1];
+};
+
+static int bundle_assoc_hash(const void *obj, int flags)
+{
+	const struct bundle_assoc *assoc = obj;
+	const char *tag = flags & OBJ_KEY ? obj : assoc->tag;
+
+	return ast_str_hash(tag);
+}
+
+static int bundle_assoc_cmp(void *obj, void *arg, int flags)
+{
+	struct bundle_assoc *assoc1 = obj;
+	struct bundle_assoc *assoc2 = arg;
+	const char *tag2 = flags & OBJ_KEY ? arg : assoc2->tag;
+
+	return strcmp(assoc1->tag, tag2) ? 0 : CMP_MATCH | CMP_STOP;
+}
+
+/* return must be ast_freed */
+static pjmedia_sdp_attr *media_get_mid(pjmedia_sdp_media *media)
+{
+	pjmedia_sdp_attr *attr = pjmedia_sdp_media_find_attr2(media, "mid", NULL);
+	if (!attr) {
+		return NULL;
+	}
+
+	return attr;
+}
+
+static int get_bundle_port(const pjmedia_sdp_session *sdp, const char *mid)
+{
+	int i;
+	for (i = 0; i < sdp->media_count; ++i) {
+		pjmedia_sdp_attr *mid_attr = media_get_mid(sdp->media[i]);
+		if (mid_attr && !pj_strcmp2(&mid_attr->value, mid)) {
+			return sdp->media[i]->desc.port;
+		}
+	}
+
+	return -1;
+}
+
+static int validate_incoming_sdp(const pjmedia_sdp_session *sdp)
+{
+	int i;
+	RAII_VAR(struct ao2_container *, portlist, ao2_container_alloc(5, validate_port_hash, validate_port_cmp), ao2_cleanup);
+	RAII_VAR(struct ao2_container *, bundle_assoc_list, ao2_container_alloc(5, bundle_assoc_hash, bundle_assoc_cmp), ao2_cleanup);
+
+	/* check for bundles (for websocket RTP multiplexing, there can be more than one) */
+	for (i = 0; i < sdp->attr_count; ++i) {
+		char *bundle_list;
+		int bundle_port = 0;
+		if (pj_stricmp2(&sdp->attr[i]->name, "group")) {
+			continue;
+		}
+
+		/* check to see if this group is a bundle */
+		if (7 >= sdp->attr[i]->value.slen || pj_strnicmp2(&sdp->attr[i]->value, "bundle ", 7)) {
+			continue;
+		}
+
+		bundle_list = ast_alloca(sdp->attr[i]->value.slen - 6);
+		strncpy(bundle_list, sdp->attr[i]->value.ptr + 7, sdp->attr[i]->value.slen - 7);
+		bundle_list[sdp->attr[i]->value.slen - 7] = '\0';
+		while (bundle_list) {
+			char *item;
+			RAII_VAR(struct bundle_assoc *, assoc, NULL, ao2_cleanup);
+			item = strsep(&bundle_list, " ,");
+			if (!bundle_port) {
+				RAII_VAR(int *, port, ao2_alloc(sizeof(int), NULL), ao2_cleanup);
+				RAII_VAR(int *, port_match, NULL, ao2_cleanup);
+				bundle_port = get_bundle_port(sdp, item);
+				if (bundle_port < 0) {
+					return -1;
+				}
+				port_match = ao2_find(portlist, &bundle_port, OBJ_KEY);
+				if (port_match) {
+					/* bundle port aready consumed by a different bundle */
+					return -1;
+				}
+				*port = bundle_port;
+				ao2_link(portlist, port);
+			}
+			assoc = ao2_alloc(sizeof(*assoc) + strlen(item), NULL);
+			if (!assoc) {
+				return -1;
+			}
+
+			/* safe use of strcpy */
+			strcpy(assoc->tag, item);
+			assoc->port = bundle_port;
+			ao2_link(bundle_assoc_list, assoc);
+		}
+	}
+
+	/* validate all streams */
+	for (i = 0; i < sdp->media_count; ++i) {
+		RAII_VAR(int *, port, ao2_alloc(sizeof(int), NULL), ao2_cleanup);
+		RAII_VAR(int *, port_match, NULL, ao2_cleanup);
+		RAII_VAR(int *, bundle_match, NULL, ao2_cleanup);
+		*port = sdp->media[i]->desc.port;
+		port_match = ao2_find(portlist, port, OBJ_KEY);
+		if (port_match) {
+			RAII_VAR(struct bundle_assoc *, assoc, NULL, ao2_cleanup);
+			pjmedia_sdp_attr *mid = media_get_mid(sdp->media[i]);
+			char *mid_val;
+
+			if (!mid) {
+				/* not part of a bundle */
+				return -1;
+			}
+
+			mid_val = ast_alloca(mid->value.slen + 1);
+			strncpy(mid_val, mid->value.ptr, mid->value.slen);
+			mid_val[mid->value.slen] = '\0';
+
+			assoc = ao2_find(bundle_assoc_list, mid_val, OBJ_KEY);
+			if (!assoc || assoc->port != *port) {
+				/* This port already exists elsewhere in the SDP
+				 * and is not an appropriate bundle port, fail
+				 * catastrophically */
+				return -1;
+			}
+		}
+		ao2_link(portlist, port);
+	}
+	return 0;
+}
+
+static int handle_incoming_sdp(struct ast_sip_session *session, const pjmedia_sdp_session *sdp)
+{
+	int i;
+	if (validate_incoming_sdp(sdp)) {
+		return -1;
+	}
+
+	for (i = 0; i < sdp->media_count; ++i) {
+		/* See if there are registered handlers for this media stream type */
+		char media[20];
+		struct ast_sip_session_sdp_handler *handler;
+		RAII_VAR(struct sdp_handler_list *, handler_list, NULL, ao2_cleanup);
+		RAII_VAR(struct ast_sip_session_media *, session_media, NULL, ao2_cleanup);
+
+		/* We need a null-terminated version of the media string */
+		ast_copy_pj_str(media, &sdp->media[i]->desc.media, sizeof(media));
+
+		session_media = ao2_find(session->media, media, OBJ_KEY);
+		if (!session_media) {
+			/* if the session_media doesn't exist, there weren't
+			 * any handlers at the time of its creation */
+			continue;
+		}
+
+		if (session_media->handler) {
+			int res;
+			handler = session_media->handler;
+			res = handler->negotiate_incoming_sdp_stream(
+				session, session_media, sdp, sdp->media[i]);
+			if (res <= 0) {
+				/* Catastrophic failure or ignored by assigned handler. Abort! */
+				return -1;
+			}
+			if (res > 0) {
+				/* Handled by this handler. Move to the next stream */
+				continue;
+			}
+		}
+
+		handler_list = ao2_find(sdp_handlers, media, OBJ_KEY);
+		if (!handler_list) {
+			ast_debug(1, "No registered SDP handlers for media type '%s'\n", media);
+			continue;
+		}
+		AST_LIST_TRAVERSE(&handler_list->list, handler, next) {
+			int res;
+			if (session_media->handler) {
+				/* There is only one slot for this stream type and it has already been claimed
+				 * so it will go unhandled */
+				break;
+			}
+			res = handler->negotiate_incoming_sdp_stream(session, session_media, sdp, sdp->media[i]);
+			if (res < 0) {
+				/* Catastrophic failure. Abort! */
+				return -1;
+			}
+			if (res > 0) {
+				/* Handled by this handler. Move to the next stream */
+				session_media->handler = handler;
+				break;
+			}
+		}
+	}
+	return 0;
+}
+
+struct handle_negotiated_sdp_cb {
+	struct ast_sip_session *session;
+	const pjmedia_sdp_session *local;
+	const pjmedia_sdp_session *remote;
+};
+
+static int handle_negotiated_sdp_session_media(void *obj, void *arg, int flags)
+{
+	struct ast_sip_session_media *session_media = obj;
+	struct handle_negotiated_sdp_cb *callback_data = arg;
+	struct ast_sip_session *session = callback_data->session;
+	const pjmedia_sdp_session *local = callback_data->local;
+	const pjmedia_sdp_session *remote = callback_data->remote;
+	int i;
+
+	for (i = 0; i < local->media_count; ++i) {
+		/* See if there are registered handlers for this media stream type */
+		char media[20];
+		struct ast_sip_session_sdp_handler *handler;
+		RAII_VAR(struct sdp_handler_list *, handler_list, NULL, ao2_cleanup);
+
+		if (!remote->media[i]) {
+			continue;
+		}
+
+		/* We need a null-terminated version of the media string */
+		ast_copy_pj_str(media, &local->media[i]->desc.media, sizeof(media));
+
+		/* stream type doesn't match the one we're looking to fill */
+		if (strcasecmp(session_media->stream_type, media)) {
+			continue;
+		}
+
+		handler = session_media->handler;
+		if (handler) {
+			int res = handler->apply_negotiated_sdp_stream(session, session_media, local, local->media[i], remote, remote->media[i]);
+			if (res >= 0) {
+				return CMP_MATCH;
+			}
+			return 0;
+		}
+
+		handler_list = ao2_find(sdp_handlers, media, OBJ_KEY);
+		if (!handler_list) {
+			ast_debug(1, "No registered SDP handlers for media type '%s'\n", media);
+			continue;
+		}
+		AST_LIST_TRAVERSE(&handler_list->list, handler, next) {
+			int res = handler->apply_negotiated_sdp_stream(session, session_media, local, local->media[i], remote, remote->media[i]);
+			if (res < 0) {
+				/* Catastrophic failure. Abort! */
+				return 0;
+			}
+			if (res > 0) {
+				/* Handled by this handler. Move to the next stream */
+				session_media->handler = handler;
+				return CMP_MATCH;
+			}
+		}
+	}
+	return CMP_MATCH;
+}
+
+static int handle_negotiated_sdp(struct ast_sip_session *session, const pjmedia_sdp_session *local, const pjmedia_sdp_session *remote)
+{
+	RAII_VAR(struct ao2_iterator *, successful, NULL, ao2_iterator_cleanup);
+	struct handle_negotiated_sdp_cb callback_data = {
+		.session = session,
+		.local = local,
+		.remote = remote,
+	};
+
+	successful = ao2_callback(session->media, OBJ_MULTIPLE, handle_negotiated_sdp_session_media, &callback_data);
+	if (successful && ao2_container_count(successful->c) == ao2_container_count(session->media)) {
+		/* Nothing experienced a catastrophic failure */
+		return 0;
+	}
+	return -1;
+}
+
+AST_RWLIST_HEAD_STATIC(session_supplements, ast_sip_session_supplement);
+
+int ast_sip_session_register_supplement(struct ast_sip_session_supplement *supplement)
+{
+	struct ast_sip_session_supplement *iter;
+	int inserted = 0;
+	SCOPED_LOCK(lock, &session_supplements, AST_RWLIST_WRLOCK, AST_RWLIST_UNLOCK);
+
+	AST_RWLIST_TRAVERSE_SAFE_BEGIN(&session_supplements, iter, next) {
+		if (iter->priority > supplement->priority) {
+			AST_RWLIST_INSERT_BEFORE_CURRENT(supplement, next);
+			inserted = 1;
+			break;
+		}
+	}
+	AST_RWLIST_TRAVERSE_SAFE_END;
+
+	if (!inserted) {
+		AST_RWLIST_INSERT_TAIL(&session_supplements, supplement, next);
+	}
+	ast_module_ref(ast_module_info->self);
+	return 0;
+}
+
+void ast_sip_session_unregister_supplement(struct ast_sip_session_supplement *supplement)
+{
+	struct ast_sip_session_supplement *iter;
+	SCOPED_LOCK(lock, &session_supplements, AST_RWLIST_WRLOCK, AST_RWLIST_UNLOCK);
+	AST_RWLIST_TRAVERSE_SAFE_BEGIN(&session_supplements, iter, next) {
+		if (supplement == iter) {
+			AST_RWLIST_REMOVE_CURRENT(next);
+			ast_module_unref(ast_module_info->self);
+			break;
+		}
+	}
+	AST_RWLIST_TRAVERSE_SAFE_END;
+}
+
+static struct ast_sip_session_supplement *supplement_dup(const struct ast_sip_session_supplement *src)
+{
+	struct ast_sip_session_supplement *dst = ast_calloc(1, sizeof(*dst));
+	if (!dst) {
+		return NULL;
+	}
+	/* Will need to revisit if shallow copy becomes an issue */
+	*dst = *src;
+	return dst;
+}
+
+#define DATASTORE_BUCKETS 53
+#define MEDIA_BUCKETS 7
+
+static void session_datastore_destroy(void *obj)
+{
+	struct ast_datastore *datastore = obj;
+
+	/* Using the destroy function (if present) destroy the data */
+	if (datastore->info->destroy != NULL && datastore->data != NULL) {
+		datastore->info->destroy(datastore->data);
+		datastore->data = NULL;
+	}
+
+	ast_free((void *) datastore->uid);
+	datastore->uid = NULL;
+}
+
+struct ast_datastore *ast_sip_session_alloc_datastore(const struct ast_datastore_info *info, const char *uid)
+{
+	RAII_VAR(struct ast_datastore *, datastore, NULL, ao2_cleanup);
+	const char *uid_ptr = uid;
+
+	if (!info) {
+		return NULL;
+	}
+
+	datastore = ao2_alloc(sizeof(*datastore), session_datastore_destroy);
+	if (!datastore) {
+		return NULL;
+	}
+
+	datastore->info = info;
+	if (ast_strlen_zero(uid)) {
+		/* They didn't provide an ID so we'll provide one ourself */
+		struct ast_uuid *uuid = ast_uuid_generate();
+		char uuid_buf[AST_UUID_STR_LEN];
+		if (!uuid) {
+			return NULL;
+		}
+		uid_ptr = ast_uuid_to_str(uuid, uuid_buf, sizeof(uuid_buf));
+		ast_free(uuid);
+	}
+
+	datastore->uid = ast_strdup(uid_ptr);
+	if (!datastore->uid) {
+		return NULL;
+	}
+
+	ao2_ref(datastore, +1);
+	return datastore;
+}
+
+int ast_sip_session_add_datastore(struct ast_sip_session *session, struct ast_datastore *datastore)
+{
+	ast_assert(datastore != NULL);
+	ast_assert(datastore->info != NULL);
+	ast_assert(ast_strlen_zero(datastore->uid) == 0);
+
+	if (!ao2_link(session->datastores, datastore)) {
+		return -1;
+	}
+	return 0;
+}
+
+struct ast_datastore *ast_sip_session_get_datastore(struct ast_sip_session *session, const char *name)
+{
+	return ao2_find(session->datastores, name, OBJ_KEY);
+}
+
+void ast_sip_session_remove_datastore(struct ast_sip_session *session, const char *name)
+{
+	ao2_callback(session->datastores, OBJ_KEY | OBJ_UNLINK | OBJ_NODATA, NULL, (void *) name);
+}
+
+/*!
+ * \brief Structure used for sending delayed requests
+ *
+ * Requests are typically delayed because the current transaction
+ * state of an INVITE. Once the pending INVITE transaction terminates,
+ * the delayed request will be sent
+ */
+struct ast_sip_session_delayed_request {
+	/*! Method of the request */
+	char method[15];
+	/*! Callback to call when the delayed request is created. */
+	ast_sip_session_request_creation_cb on_request_creation;
+	/*! Callback to call when the delayed request SDP is created */
+	ast_sip_session_sdp_creation_cb on_sdp_creation;
+	/*! Callback to call when the delayed request receives a response */
+	ast_sip_session_response_cb on_response;
+	/*! Request to send */
+	pjsip_tx_data *tdata;
+	AST_LIST_ENTRY(ast_sip_session_delayed_request) next;
+};
+
+static struct ast_sip_session_delayed_request *delayed_request_alloc(const char *method,
+		ast_sip_session_request_creation_cb on_request_creation,
+		ast_sip_session_sdp_creation_cb on_sdp_creation,
+		ast_sip_session_response_cb on_response,
+		pjsip_tx_data *tdata)
+{
+	struct ast_sip_session_delayed_request *delay = ast_calloc(1, sizeof(*delay));
+	if (!delay) {
+		return NULL;
+	}
+	ast_copy_string(delay->method, method, sizeof(delay->method));
+	delay->on_request_creation = on_request_creation;
+	delay->on_sdp_creation = on_sdp_creation;
+	delay->on_response = on_response;
+	delay->tdata = tdata;
+	return delay;
+}
+
+static int send_delayed_request(struct ast_sip_session *session, struct ast_sip_session_delayed_request *delay)
+{
+	ast_debug(3, "Sending delayed %s request to %s\n", delay->method, ast_sorcery_object_get_id(session->endpoint));
+
+	if (delay->tdata) {
+		ast_sip_session_send_request_with_cb(session, delay->tdata, delay->on_response);
+		return 0;
+	}
+
+	if (!strcmp(delay->method, "INVITE")) {
+		ast_sip_session_refresh(session, delay->on_request_creation,
+				delay->on_sdp_creation, delay->on_response, AST_SIP_SESSION_REFRESH_METHOD_INVITE, 1);
+	} else if (!strcmp(delay->method, "UPDATE")) {
+		ast_sip_session_refresh(session, delay->on_request_creation,
+				delay->on_sdp_creation, delay->on_response, AST_SIP_SESSION_REFRESH_METHOD_UPDATE, 1);
+	} else {
+		ast_log(LOG_WARNING, "Unexpected delayed %s request with no existing request structure\n", delay->method);
+		return -1;
+	}
+	return 0;
+}
+
+static int queued_delayed_request_send(void *data)
+{
+	RAII_VAR(struct ast_sip_session *, session, data, ao2_cleanup);
+	RAII_VAR(struct ast_sip_session_delayed_request *, delay, NULL, ast_free_ptr);
+
+	delay = AST_LIST_REMOVE_HEAD(&session->delayed_requests, next);
+	if (!delay) {
+		return 0;
+	}
+
+	return send_delayed_request(session, delay);
+}
+
+static void queue_delayed_request(struct ast_sip_session *session)
+{
+	if (AST_LIST_EMPTY(&session->delayed_requests)) {
+		/* No delayed request to send, so just return */
+		return;
+	}
+
+	ast_debug(3, "Queuing delayed request to run for %s\n",
+			ast_sorcery_object_get_id(session->endpoint));
+
+	ao2_ref(session, +1);
+	ast_sip_push_task(session->serializer, queued_delayed_request_send, session);
+}
+
+static int delay_request(struct ast_sip_session *session, ast_sip_session_request_creation_cb on_request,
+		ast_sip_session_sdp_creation_cb on_sdp_creation, ast_sip_session_response_cb on_response,
+		const char *method, pjsip_tx_data *tdata)
+{
+	struct ast_sip_session_delayed_request *delay = delayed_request_alloc(method,
+			on_request, on_sdp_creation, on_response, tdata);
+
+	if (!delay) {
+		return -1;
+	}
+
+	AST_LIST_INSERT_TAIL(&session->delayed_requests, delay, next);
+	return 0;
+}
+
+static pjmedia_sdp_session *generate_session_refresh_sdp(struct ast_sip_session *session)
+{
+	pjsip_inv_session *inv_session = session->inv_session;
+	const pjmedia_sdp_session *previous_sdp;
+
+	if (pjmedia_sdp_neg_was_answer_remote(inv_session->neg)) {
+		pjmedia_sdp_neg_get_active_remote(inv_session->neg, &previous_sdp);
+	} else {
+		pjmedia_sdp_neg_get_active_local(inv_session->neg, &previous_sdp);
+	}
+	return create_local_sdp(inv_session, session, previous_sdp);
+}
+
+int ast_sip_session_refresh(struct ast_sip_session *session,
+		ast_sip_session_request_creation_cb on_request_creation,
+		ast_sip_session_sdp_creation_cb on_sdp_creation,
+		ast_sip_session_response_cb on_response,
+		enum ast_sip_session_refresh_method method, int generate_new_sdp)
+{
+	pjsip_inv_session *inv_session = session->inv_session;
+	pjmedia_sdp_session *new_sdp = NULL;
+	pjsip_tx_data *tdata;
+
+	if (inv_session->state == PJSIP_INV_STATE_DISCONNECTED) {
+		/* Don't try to do anything with a hung-up call */
+		ast_debug(3, "Not sending reinvite to %s because of disconnected state...\n",
+				ast_sorcery_object_get_id(session->endpoint));
+		return 0;
+	}
+
+	if (method == AST_SIP_SESSION_REFRESH_METHOD_INVITE) {
+		if (inv_session->invite_tsx) {
+			/* We can't send a reinvite yet, so delay it */
+			ast_debug(3, "Delaying sending reinvite to %s because of outstanding transaction...\n",
+					ast_sorcery_object_get_id(session->endpoint));
+			return delay_request(session, on_request_creation, on_sdp_creation, on_response, "INVITE", NULL);
+		} else if (inv_session->state != PJSIP_INV_STATE_CONFIRMED) {
+			/* Initial INVITE transaction failed to progress us to a confirmed state
+			 * which means re-invites are not possible
+			 */
+			ast_debug(3, "Not sending reinvite to %s because not in confirmed state...\n",
+					ast_sorcery_object_get_id(session->endpoint));
+			return 0;
+		}
+	}
+
+	if (generate_new_sdp) {
+		new_sdp = generate_session_refresh_sdp(session);
+		if (!new_sdp) {
+			ast_log(LOG_ERROR, "Failed to generate session refresh SDP. Not sending session refresh\n");
+			return -1;
+		}
+		if (on_sdp_creation) {
+			if (on_sdp_creation(session, new_sdp)) {
+				return -1;
+			}
+		}
+	}
+
+	if (method == AST_SIP_SESSION_REFRESH_METHOD_INVITE) {
+		if (pjsip_inv_reinvite(inv_session, NULL, new_sdp, &tdata)) {
+			ast_log(LOG_WARNING, "Failed to create reinvite properly.\n");
+			return -1;
+		}
+	} else if (pjsip_inv_update(inv_session, NULL, new_sdp, &tdata)) {
+		ast_log(LOG_WARNING, "Failed to create UPDATE properly.\n");
+		return -1;
+	}
+	if (on_request_creation) {
+		if (on_request_creation(session, tdata)) {
+			return -1;
+		}
+	}
+	ast_sip_session_send_request_with_cb(session, tdata, on_response);
+	return 0;
+}
+
+void ast_sip_session_send_response(struct ast_sip_session *session, pjsip_tx_data *tdata)
+{
+	handle_outgoing_response(session, tdata);
+	pjsip_inv_send_msg(session->inv_session, tdata);
+	return;
+}
+
+static pj_bool_t session_on_rx_request(pjsip_rx_data *rdata);
+
+static pjsip_module session_module = {
+	.name = {"Session Module", 14},
+	.priority = PJSIP_MOD_PRIORITY_APPLICATION,
+	.on_rx_request = session_on_rx_request,
+};
+
+/*! \brief Determine whether the SDP provided requires deferral of negotiating or not
+ *
+ * \retval 1 re-invite should be deferred and resumed later
+ * \retval 0 re-invite should not be deferred
+ */
+static int sdp_requires_deferral(struct ast_sip_session *session, const pjmedia_sdp_session *sdp)
+{
+	int i;
+	if (validate_incoming_sdp(sdp)) {
+		return 0;
+	}
+
+	for (i = 0; i < sdp->media_count; ++i) {
+		/* See if there are registered handlers for this media stream type */
+		char media[20];
+		struct ast_sip_session_sdp_handler *handler;
+		RAII_VAR(struct sdp_handler_list *, handler_list, NULL, ao2_cleanup);
+		RAII_VAR(struct ast_sip_session_media *, session_media, NULL, ao2_cleanup);
+
+		/* We need a null-terminated version of the media string */
+		ast_copy_pj_str(media, &sdp->media[i]->desc.media, sizeof(media));
+
+		session_media = ao2_find(session->media, media, OBJ_KEY);
+		if (!session_media) {
+			/* if the session_media doesn't exist, there weren't
+			 * any handlers at the time of its creation */
+			continue;
+		}
+
+		if (session_media->handler && session_media->handler->defer_incoming_sdp_stream) {
+			int res;
+			handler = session_media->handler;
+			res = handler->defer_incoming_sdp_stream(
+				session, session_media, sdp, sdp->media[i]);
+			if (res) {
+				return 1;
+			}
+		}
+
+		handler_list = ao2_find(sdp_handlers, media, OBJ_KEY);
+		if (!handler_list) {
+			ast_debug(1, "No registered SDP handlers for media type '%s'\n", media);
+			continue;
+		}
+		AST_LIST_TRAVERSE(&handler_list->list, handler, next) {
+			int res;
+			if (session_media->handler) {
+				/* There is only one slot for this stream type and it has already been claimed
+				 * so it will go unhandled */
+				break;
+			}
+			if (!handler->defer_incoming_sdp_stream) {
+				continue;
+			}
+			res = handler->defer_incoming_sdp_stream(session, session_media, sdp, sdp->media[i]);
+			if (res) {
+				return 1;
+			}
+		}
+	}
+	return 0;
+}
+
+static pj_bool_t session_reinvite_on_rx_request(pjsip_rx_data *rdata)
+{
+	pjsip_dialog *dlg;
+	RAII_VAR(struct ast_sip_session *, session, NULL, ao2_cleanup);
+	pjsip_rdata_sdp_info *sdp_info;
+
+	if (rdata->msg_info.msg->line.req.method.id != PJSIP_INVITE_METHOD ||
+		!(dlg = pjsip_ua_find_dialog(&rdata->msg_info.cid->id, &rdata->msg_info.to->tag, &rdata->msg_info.from->tag, PJ_FALSE)) ||
+		!(session = ast_sip_dialog_get_session(dlg))) {
+		return PJ_FALSE;
+	}
+
+	if (session->deferred_reinvite) {
+		pj_str_t key, deferred_key;
+		pjsip_tx_data *tdata;
+
+		/* We use memory from the new request on purpose so the deferred reinvite pool does not grow uncontrollably */
+		pjsip_tsx_create_key(rdata->tp_info.pool, &key, PJSIP_ROLE_UAS, &rdata->msg_info.cseq->method, rdata);
+		pjsip_tsx_create_key(rdata->tp_info.pool, &deferred_key, PJSIP_ROLE_UAS, &session->deferred_reinvite->msg_info.cseq->method,
+			session->deferred_reinvite);
+
+		/* If this is a retransmission ignore it */
+		if (!pj_strcmp(&key, &deferred_key)) {
+			return PJ_TRUE;
+		}
+
+		/* Otherwise this is a new re-invite, so reject it */
+		if (pjsip_dlg_create_response(dlg, rdata, 491, NULL, &tdata) == PJ_SUCCESS) {
+			pjsip_endpt_send_response2(ast_sip_get_pjsip_endpoint(), rdata, tdata, NULL, NULL);
+		}
+
+		return PJ_TRUE;
+	}
+
+	if (!(sdp_info = pjsip_rdata_get_sdp_info(rdata)) ||
+		(sdp_info->sdp_err != PJ_SUCCESS) ||
+		!sdp_info->sdp ||
+		!sdp_requires_deferral(session, sdp_info->sdp)) {
+		return PJ_FALSE;
+	}
+
+	pjsip_rx_data_clone(rdata, 0, &session->deferred_reinvite);
+
+	return PJ_TRUE;
+}
+
+void ast_sip_session_resume_reinvite(struct ast_sip_session *session)
+{
+	if (!session->deferred_reinvite) {
+		return;
+	}
+
+	pjsip_endpt_process_rx_data(ast_sip_get_pjsip_endpoint(), session->deferred_reinvite, NULL, NULL);
+	pjsip_rx_data_free_cloned(session->deferred_reinvite);
+	session->deferred_reinvite = NULL;
+}
+
+static pjsip_module session_reinvite_module = {
+	.name = { "Session Re-Invite Module", 24 },
+	.priority = PJSIP_MOD_PRIORITY_UA_PROXY_LAYER - 1,
+	.on_rx_request = session_reinvite_on_rx_request,
+};
+
+void ast_sip_session_send_request_with_cb(struct ast_sip_session *session, pjsip_tx_data *tdata,
+		ast_sip_session_response_cb on_response)
+{
+	pjsip_inv_session *inv_session = session->inv_session;
+
+	if (inv_session->state == PJSIP_INV_STATE_DISCONNECTED) {
+		/* Don't try to do anything with a hung-up call */
+		return;
+	}
+
+	tdata->mod_data[session_module.id] = on_response;
+	handle_outgoing_request(session, tdata);
+	pjsip_inv_send_msg(session->inv_session, tdata);
+	return;
+}
+
+void ast_sip_session_send_request(struct ast_sip_session *session, pjsip_tx_data *tdata)
+{
+	ast_sip_session_send_request_with_cb(session, tdata, NULL);
+}
+
+int ast_sip_session_create_invite(struct ast_sip_session *session, pjsip_tx_data **tdata)
+{
+	pjmedia_sdp_session *offer;
+
+	if (!(offer = create_local_sdp(session->inv_session, session, NULL))) {
+		pjsip_inv_terminate(session->inv_session, 500, PJ_FALSE);
+		return -1;
+	}
+
+	pjsip_inv_set_local_sdp(session->inv_session, offer);
+	pjmedia_sdp_neg_set_prefer_remote_codec_order(session->inv_session->neg, PJ_FALSE);
+	if (pjsip_inv_invite(session->inv_session, tdata) != PJ_SUCCESS) {
+		return -1;
+	}
+	return 0;
+}
+
+static int datastore_hash(const void *obj, int flags)
+{
+	const struct ast_datastore *datastore = obj;
+	const char *uid = flags & OBJ_KEY ? obj : datastore->uid;
+
+	ast_assert(uid != NULL);
+
+	return ast_str_hash(uid);
+}
+
+static int datastore_cmp(void *obj, void *arg, int flags)
+{
+	const struct ast_datastore *datastore1 = obj;
+	const struct ast_datastore *datastore2 = arg;
+	const char *uid2 = flags & OBJ_KEY ? arg : datastore2->uid;
+
+	ast_assert(datastore1->uid != NULL);
+	ast_assert(uid2 != NULL);
+
+	return strcmp(datastore1->uid, uid2) ? 0 : CMP_MATCH | CMP_STOP;
+}
+
+static void session_media_dtor(void *obj)
+{
+	struct ast_sip_session_media *session_media = obj;
+	if (session_media->handler) {
+		session_media->handler->stream_destroy(session_media);
+	}
+	if (session_media->srtp) {
+		ast_sdp_srtp_destroy(session_media->srtp);
+	}
+}
+
+static void session_destructor(void *obj)
+{
+	struct ast_sip_session *session = obj;
+	struct ast_sip_session_supplement *supplement;
+	struct ast_sip_session_delayed_request *delay;
+
+	ast_debug(3, "Destroying SIP session with endpoint %s\n",
+			ast_sorcery_object_get_id(session->endpoint));
+
+	while ((supplement = AST_LIST_REMOVE_HEAD(&session->supplements, next))) {
+		if (supplement->session_destroy) {
+			supplement->session_destroy(session);
+		}
+		ast_free(supplement);
+	}
+
+	ast_taskprocessor_unreference(session->serializer);
+	ao2_cleanup(session->datastores);
+	ao2_cleanup(session->media);
+
+	AST_LIST_HEAD_DESTROY(&session->supplements);
+	while ((delay = AST_LIST_REMOVE_HEAD(&session->delayed_requests, next))) {
+		ast_free(delay);
+	}
+	ast_party_id_free(&session->id);
+	ao2_cleanup(session->endpoint);
+	ast_format_cap_destroy(session->req_caps);
+
+	if (session->dsp) {
+		ast_dsp_free(session->dsp);
+	}
+
+	if (session->inv_session) {
+		pjsip_dlg_dec_session(session->inv_session->dlg, &session_module);
+	}
+}
+
+static int add_supplements(struct ast_sip_session *session)
+{
+	struct ast_sip_session_supplement *iter;
+	SCOPED_LOCK(lock, &session_supplements, AST_RWLIST_RDLOCK, AST_RWLIST_UNLOCK);
+
+	AST_RWLIST_TRAVERSE(&session_supplements, iter, next) {
+		struct ast_sip_session_supplement *copy = supplement_dup(iter);
+		if (!copy) {
+			return -1;
+		}
+		AST_LIST_INSERT_TAIL(&session->supplements, copy, next);
+	}
+	return 0;
+}
+
+static int add_session_media(void *obj, void *arg, int flags)
+{
+	struct sdp_handler_list *handler_list = obj;
+	struct ast_sip_session * session = arg;
+	RAII_VAR(struct ast_sip_session_media *, session_media, NULL, ao2_cleanup);
+	session_media = ao2_alloc(sizeof(*session_media) + strlen(handler_list->stream_type), session_media_dtor);
+	if (!session_media) {
+		return CMP_STOP;
+	}
+	/* Safe use of strcpy */
+	strcpy(session_media->stream_type, handler_list->stream_type);
+	ao2_link(session->media, session_media);
+	return 0;
+}
+
+/*! \brief Destructor for SIP channel */
+static void sip_channel_destroy(void *obj)
+{
+	struct ast_sip_channel_pvt *channel = obj;
+
+	ao2_cleanup(channel->pvt);
+	ao2_cleanup(channel->session);
+}
+
+struct ast_sip_channel_pvt *ast_sip_channel_pvt_alloc(void *pvt, struct ast_sip_session *session)
+{
+	struct ast_sip_channel_pvt *channel = ao2_alloc(sizeof(*channel), sip_channel_destroy);
+
+	if (!channel) {
+		return NULL;
+	}
+
+	ao2_ref(pvt, +1);
+	channel->pvt = pvt;
+	ao2_ref(session, +1);
+	channel->session = session;
+
+	return channel;
+}
+
+struct ast_sip_session *ast_sip_session_alloc(struct ast_sip_endpoint *endpoint, pjsip_inv_session *inv_session)
+{
+	RAII_VAR(struct ast_sip_session *, session, ao2_alloc(sizeof(*session), session_destructor), ao2_cleanup);
+	struct ast_sip_session_supplement *iter;
+	int dsp_features = 0;
+	if (!session) {
+		return NULL;
+	}
+	AST_LIST_HEAD_INIT(&session->supplements);
+	session->datastores = ao2_container_alloc(DATASTORE_BUCKETS, datastore_hash, datastore_cmp);
+	if (!session->datastores) {
+		return NULL;
+	}
+
+	session->media = ao2_container_alloc(MEDIA_BUCKETS, session_media_hash, session_media_cmp);
+	if (!session->media) {
+		return NULL;
+	}
+	/* fill session->media with available types */
+	ao2_callback(sdp_handlers, OBJ_NODATA, add_session_media, session);
+
+	session->serializer = ast_sip_create_serializer();
+	if (!session->serializer) {
+		return NULL;
+	}
+	ast_sip_dialog_set_serializer(inv_session->dlg, session->serializer);
+	ast_sip_dialog_set_endpoint(inv_session->dlg, endpoint);
+	pjsip_dlg_inc_session(inv_session->dlg, &session_module);
+	ao2_ref(session, +1);
+	inv_session->mod_data[session_module.id] = session;
+	ao2_ref(endpoint, +1);
+	session->endpoint = endpoint;
+	session->inv_session = inv_session;
+	session->req_caps = ast_format_cap_alloc_nolock();
+
+	if (endpoint->dtmf == AST_SIP_DTMF_INBAND) {
+		dsp_features |= DSP_FEATURE_DIGIT_DETECT;
+	}
+
+	if (endpoint->faxdetect) {
+		dsp_features |= DSP_FEATURE_FAX_DETECT;
+	}
+
+	if (dsp_features) {
+		if (!(session->dsp = ast_dsp_new())) {
+			ao2_ref(session, -1);
+			return NULL;
+		}
+
+		ast_dsp_set_features(session->dsp, dsp_features);
+	}
+
+	if (add_supplements(session)) {
+		ao2_ref(session, -1);
+		return NULL;
+	}
+	AST_LIST_TRAVERSE(&session->supplements, iter, next) {
+		if (iter->session_begin) {
+			iter->session_begin(session);
+		}
+	}
+	session->direct_media_cap = ast_format_cap_alloc_nolock();
+	AST_LIST_HEAD_INIT_NOLOCK(&session->delayed_requests);
+	ast_party_id_init(&session->id);
+	ao2_ref(session, +1);
+	return session;
+}
+
+static int session_outbound_auth(pjsip_dialog *dlg, pjsip_tx_data *tdata, void *user_data)
+{
+	pjsip_inv_session *inv = pjsip_dlg_get_inv_session(dlg);
+	struct ast_sip_session *session = inv->mod_data[session_module.id];
+
+	if (inv->state < PJSIP_INV_STATE_CONFIRMED && tdata->msg->line.req.method.id == PJSIP_INVITE_METHOD) {
+		pjsip_inv_uac_restart(inv, PJ_TRUE);
+	}
+	ast_sip_session_send_request(session, tdata);
+	return 0;
+}
+
+struct ast_sip_session *ast_sip_session_create_outgoing(struct ast_sip_endpoint *endpoint, const char *location, const char *request_user, struct ast_format_cap *req_caps)
+{
+	const char *uri = NULL;
+	RAII_VAR(struct ast_sip_contact *, contact, NULL, ao2_cleanup);
+	pjsip_timer_setting timer;
+	pjsip_dialog *dlg;
+	struct pjsip_inv_session *inv_session;
+	RAII_VAR(struct ast_sip_session *, session, NULL, ao2_cleanup);
+
+	/* If no location has been provided use the AOR list from the endpoint itself */
+	location = S_OR(location, endpoint->aors);
+
+	contact = ast_sip_location_retrieve_contact_from_aor_list(location);
+	if (!contact || ast_strlen_zero(contact->uri)) {
+		uri = location;
+	} else {
+		uri = contact->uri;
+	}
+
+	/* If we still have no URI to dial fail to create the session */
+	if (ast_strlen_zero(uri)) {
+		return NULL;
+	}
+
+	if (!(dlg = ast_sip_create_dialog(endpoint, uri, request_user))) {
+		return NULL;
+	}
+
+	if (ast_sip_dialog_setup_outbound_authentication(dlg, endpoint, session_outbound_auth, NULL)) {
+		pjsip_dlg_terminate(dlg);
+		return NULL;
+	}
+
+	if (pjsip_inv_create_uac(dlg, NULL, endpoint->extensions.flags, &inv_session) != PJ_SUCCESS) {
+		pjsip_dlg_terminate(dlg);
+		return NULL;
+	}
+#ifdef PJMEDIA_SDP_NEG_ALLOW_MEDIA_CHANGE
+	inv_session->sdp_neg_flags = PJMEDIA_SDP_NEG_ALLOW_MEDIA_CHANGE;
+#endif
+
+	pjsip_timer_setting_default(&timer);
+	timer.min_se = endpoint->extensions.timer.min_se;
+	timer.sess_expires = endpoint->extensions.timer.sess_expires;
+	pjsip_timer_init_session(inv_session, &timer);
+
+	if (!(session = ast_sip_session_alloc(endpoint, inv_session))) {
+		pjsip_inv_terminate(inv_session, 500, PJ_FALSE);
+		return NULL;
+	}
+
+	ast_format_cap_copy(session->req_caps, req_caps);
+	if ((pjsip_dlg_add_usage(dlg, &session_module, NULL) != PJ_SUCCESS)) {
+		pjsip_inv_terminate(inv_session, 500, PJ_FALSE);
+		/* Since we are not notifying ourselves that the INVITE session is being terminated
+		 * we need to manually drop its reference to session
+		 */
+		ao2_ref(session, -1);
+		return NULL;
+	}
+
+	ao2_ref(session, +1);
+	return session;
+}
+
+static int session_termination_task(void *data)
+{
+	RAII_VAR(struct ast_sip_session *, session, data, ao2_cleanup);
+	pjsip_tx_data *packet = NULL;
+
+	if (!session->inv_session) {
+		return 0;
+	}
+
+	if (pjsip_inv_end_session(session->inv_session, 603, NULL, &packet) == PJ_SUCCESS) {
+		ast_sip_session_send_request(session, packet);
+	}
+
+	return 0;
+}
+
+static void session_termination_cb(pj_timer_heap_t *timer_heap, struct pj_timer_entry *entry)
+{
+	struct ast_sip_session *session = entry->user_data;
+
+	if (ast_sip_push_task(session->serializer, session_termination_task, session)) {
+		ao2_cleanup(session);
+	}
+}
+
+void ast_sip_session_defer_termination(struct ast_sip_session *session)
+{
+	pj_time_val delay = { .sec = 60, };
+
+	session->defer_terminate = 1;
+
+	session->scheduled_termination.id = 0;
+	ao2_ref(session, +1);
+	session->scheduled_termination.user_data = session;
+	session->scheduled_termination.cb = session_termination_cb;
+
+	if (pjsip_endpt_schedule_timer(ast_sip_get_pjsip_endpoint(), &session->scheduled_termination, &delay) != PJ_SUCCESS) {
+		ao2_ref(session, -1);
+	}
+}
+
+struct ast_sip_session *ast_sip_dialog_get_session(pjsip_dialog *dlg)
+{
+	pjsip_inv_session *inv_session = pjsip_dlg_get_inv_session(dlg);
+	struct ast_sip_session *session;
+
+	if (!inv_session ||
+		!(session = inv_session->mod_data[session_module.id])) {
+		return NULL;
+	}
+
+	ao2_ref(session, +1);
+
+	return session;
+}
+
+enum sip_get_destination_result {
+	/*! The extension was successfully found */
+	SIP_GET_DEST_EXTEN_FOUND,
+	/*! The extension specified in the RURI was not found */
+	SIP_GET_DEST_EXTEN_NOT_FOUND,
+	/*! The extension specified in the RURI was a partial match */
+	SIP_GET_DEST_EXTEN_PARTIAL,
+	/*! The RURI is of an unsupported scheme */
+	SIP_GET_DEST_UNSUPPORTED_URI,
+};
+
+/*!
+ * \brief Determine where in the dialplan a call should go
+ *
+ * This uses the username in the request URI to try to match
+ * an extension in the endpoint's configured context in order
+ * to route the call.
+ *
+ * \param session The inbound SIP session
+ * \param rdata The SIP INVITE
+ */
+static enum sip_get_destination_result get_destination(struct ast_sip_session *session, pjsip_rx_data *rdata)
+{
+	pjsip_uri *ruri = rdata->msg_info.msg->line.req.uri;
+	pjsip_sip_uri *sip_ruri;
+	if (!PJSIP_URI_SCHEME_IS_SIP(ruri) && !PJSIP_URI_SCHEME_IS_SIPS(ruri)) {
+		return SIP_GET_DEST_UNSUPPORTED_URI;
+	}
+	sip_ruri = pjsip_uri_get_uri(ruri);
+	ast_copy_pj_str(session->exten, &sip_ruri->user, sizeof(session->exten));
+	if (ast_exists_extension(NULL, session->endpoint->context, session->exten, 1, NULL)) {
+		return SIP_GET_DEST_EXTEN_FOUND;
+	}
+	/* XXX In reality, we'll likely have further options so that partial matches
+	 * can be indicated here, but for getting something up and running, we're going
+	 * to return a "not exists" error here.
+	 */
+	return SIP_GET_DEST_EXTEN_NOT_FOUND;
+}
+
+static pjsip_inv_session *pre_session_setup(pjsip_rx_data *rdata, const struct ast_sip_endpoint *endpoint)
+{
+	pjsip_tx_data *tdata;
+	pjsip_dialog *dlg;
+	pjsip_inv_session *inv_session;
+	unsigned int options = endpoint->extensions.flags;
+
+	if (pjsip_inv_verify_request(rdata, &options, NULL, NULL, ast_sip_get_pjsip_endpoint(), &tdata) != PJ_SUCCESS) {
+		if (tdata) {
+			pjsip_endpt_send_response2(ast_sip_get_pjsip_endpoint(), rdata, tdata, NULL, NULL);
+		} else {
+			pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 500, NULL, NULL, NULL);
+		}
+		return NULL;
+	}
+	if (pjsip_dlg_create_uas(pjsip_ua_instance(), rdata, NULL, &dlg) != PJ_SUCCESS) {
+		pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 500, NULL, NULL, NULL);
+		return NULL;
+	}
+	if (pjsip_inv_create_uas(dlg, rdata, NULL, 0, &inv_session) != PJ_SUCCESS) {
+		pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 500, NULL, NULL, NULL);
+		pjsip_dlg_terminate(dlg);
+		return NULL;
+	}
+#ifdef PJMEDIA_SDP_NEG_ALLOW_MEDIA_CHANGE
+	inv_session->sdp_neg_flags = PJMEDIA_SDP_NEG_ALLOW_MEDIA_CHANGE;
+#endif
+	if (pjsip_dlg_add_usage(dlg, &session_module, NULL) != PJ_SUCCESS) {
+		if (pjsip_inv_initial_answer(inv_session, rdata, 500, NULL, NULL, &tdata) != PJ_SUCCESS) {
+			pjsip_inv_terminate(inv_session, 500, PJ_FALSE);
+		}
+		pjsip_inv_send_msg(inv_session, tdata);
+		return NULL;
+	}
+	return inv_session;
+}
+
+struct new_invite {
+	/*! \brief Session created for the new INVITE */
+	struct ast_sip_session *session;
+
+	/*! \brief INVITE request itself */
+	pjsip_rx_data *rdata;
+};
+
+static void new_invite_destroy(void *obj)
+{
+	struct new_invite *invite = obj;
+
+	ao2_cleanup(invite->session);
+
+	if (invite->rdata) {
+		pjsip_rx_data_free_cloned(invite->rdata);
+	}
+}
+
+static struct new_invite *new_invite_alloc(struct ast_sip_session *session, pjsip_rx_data *rdata)
+{
+	struct new_invite *invite = ao2_alloc(sizeof(*invite), new_invite_destroy);
+
+	if (!invite) {
+		return NULL;
+	}
+
+	ao2_ref(session, +1);
+	invite->session = session;
+
+	if (pjsip_rx_data_clone(rdata, 0, &invite->rdata) != PJ_SUCCESS) {
+		ao2_ref(invite, -1);
+		return NULL;
+	}
+
+	return invite;
+}
+
+static int new_invite(void *data)
+{
+	RAII_VAR(struct new_invite *, invite, data, ao2_cleanup);
+	pjsip_tx_data *tdata = NULL;
+	pjsip_timer_setting timer;
+	pjsip_rdata_sdp_info *sdp_info;
+	pjmedia_sdp_session *local = NULL;
+
+	/* From this point on, any calls to pjsip_inv_terminate have the last argument as PJ_TRUE
+	 * so that we will be notified so we can destroy the session properly
+	 */
+
+	switch (get_destination(invite->session, invite->rdata)) {
+	case SIP_GET_DEST_EXTEN_FOUND:
+		/* Things worked. Keep going */
+		break;
+	case SIP_GET_DEST_UNSUPPORTED_URI:
+		if (pjsip_inv_initial_answer(invite->session->inv_session, invite->rdata, 416, NULL, NULL, &tdata) == PJ_SUCCESS) {
+			ast_sip_session_send_response(invite->session, tdata);
+		} else  {
+			pjsip_inv_terminate(invite->session->inv_session, 416, PJ_TRUE);
+		}
+		return 0;
+	case SIP_GET_DEST_EXTEN_NOT_FOUND:
+	case SIP_GET_DEST_EXTEN_PARTIAL:
+	default:
+		ast_log(LOG_NOTICE, "Call from '%s' (%s:%s:%d) to extension '%s' rejected because extension not found in context '%s'.\n",
+			ast_sorcery_object_get_id(invite->session->endpoint), invite->rdata->tp_info.transport->type_name, invite->rdata->pkt_info.src_name,
+			invite->rdata->pkt_info.src_port, invite->session->exten, invite->session->endpoint->context);
+
+		if (pjsip_inv_initial_answer(invite->session->inv_session, invite->rdata, 404, NULL, NULL, &tdata) == PJ_SUCCESS) {
+			ast_sip_session_send_response(invite->session, tdata);
+		} else  {
+			pjsip_inv_terminate(invite->session->inv_session, 404, PJ_TRUE);
+		}
+		return 0;
+	};
+
+	if ((sdp_info = pjsip_rdata_get_sdp_info(invite->rdata)) && (sdp_info->sdp_err == PJ_SUCCESS) && sdp_info->sdp) {
+		if (handle_incoming_sdp(invite->session, sdp_info->sdp)) {
+			if (pjsip_inv_initial_answer(invite->session->inv_session, invite->rdata, 488, NULL, NULL, &tdata) == PJ_SUCCESS) {
+				ast_sip_session_send_response(invite->session, tdata);
+			} else  {
+				pjsip_inv_terminate(invite->session->inv_session, 488, PJ_TRUE);
+			}
+			return 0;
+		}
+		/* We are creating a local SDP which is an answer to their offer */
+		local = create_local_sdp(invite->session->inv_session, invite->session, sdp_info->sdp);
+	} else {
+		/* We are creating a local SDP which is an offer */
+		local = create_local_sdp(invite->session->inv_session, invite->session, NULL);
+	}
+
+	/* If we were unable to create a local SDP terminate the session early, it won't go anywhere */
+	if (!local) {
+		if (pjsip_inv_initial_answer(invite->session->inv_session, invite->rdata, 500, NULL, NULL, &tdata) == PJ_SUCCESS) {
+			ast_sip_session_send_response(invite->session, tdata);
+		} else  {
+			pjsip_inv_terminate(invite->session->inv_session, 500, PJ_TRUE);
+		}
+		return 0;
+	} else {
+		pjsip_inv_set_local_sdp(invite->session->inv_session, local);
+		pjmedia_sdp_neg_set_prefer_remote_codec_order(invite->session->inv_session->neg, PJ_FALSE);
+	}
+
+	pjsip_timer_setting_default(&timer);
+	timer.min_se = invite->session->endpoint->extensions.timer.min_se;
+	timer.sess_expires = invite->session->endpoint->extensions.timer.sess_expires;
+	pjsip_timer_init_session(invite->session->inv_session, &timer);
+
+	/* At this point, we've verified what we can, so let's go ahead and send a 100 Trying out */
+	if (pjsip_inv_initial_answer(invite->session->inv_session, invite->rdata, 100, NULL, NULL, &tdata) != PJ_SUCCESS) {
+		pjsip_inv_terminate(invite->session->inv_session, 500, PJ_TRUE);
+		return 0;
+	}
+	ast_sip_session_send_response(invite->session, tdata);
+
+	handle_incoming_request(invite->session, invite->rdata);
+
+	return 0;
+}
+
+static void handle_new_invite_request(pjsip_rx_data *rdata)
+{
+	RAII_VAR(struct ast_sip_endpoint *, endpoint,
+			ast_pjsip_rdata_get_endpoint(rdata), ao2_cleanup);
+	pjsip_tx_data *tdata = NULL;
+	pjsip_inv_session *inv_session = NULL;
+	RAII_VAR(struct ast_sip_session *, session, NULL, ao2_cleanup);
+	struct new_invite *invite;
+
+	ast_assert(endpoint != NULL);
+
+	inv_session = pre_session_setup(rdata, endpoint);
+	if (!inv_session) {
+		/* pre_session_setup() returns a response on failure */
+		return;
+	}
+
+	session = ast_sip_session_alloc(endpoint, inv_session);
+	if (!session) {
+		if (pjsip_inv_initial_answer(inv_session, rdata, 500, NULL, NULL, &tdata) == PJ_SUCCESS) {
+			pjsip_inv_terminate(inv_session, 500, PJ_FALSE);
+		} else {
+			pjsip_inv_send_msg(inv_session, tdata);
+		}
+		return;
+	}
+
+	invite = new_invite_alloc(session, rdata);
+	if (!invite || ast_sip_push_task(session->serializer, new_invite, invite)) {
+		if (pjsip_inv_initial_answer(inv_session, rdata, 500, NULL, NULL, &tdata) == PJ_SUCCESS) {
+			pjsip_inv_terminate(inv_session, 500, PJ_FALSE);
+		} else {
+			pjsip_inv_send_msg(inv_session, tdata);
+		}
+		ao2_ref(session, -1);
+		ao2_cleanup(invite);
+		return;
+	}
+}
+
+static pj_bool_t does_method_match(const pj_str_t *message_method, const char *supplement_method)
+{
+	pj_str_t method;
+
+	if (ast_strlen_zero(supplement_method)) {
+		return PJ_TRUE;
+	}
+
+	pj_cstr(&method, supplement_method);
+
+	return pj_stristr(&method, message_method) ? PJ_TRUE : PJ_FALSE;
+}
+
+static pj_bool_t has_supplement(const struct ast_sip_session *session, const pjsip_rx_data *rdata)
+{
+	struct ast_sip_session_supplement *supplement;
+	struct pjsip_method *method = &rdata->msg_info.msg->line.req.method;
+
+	if (!session) {
+		return PJ_FALSE;
+	}
+
+	AST_LIST_TRAVERSE(&session->supplements, supplement, next) {
+		if (does_method_match(&method->name, supplement->method)) {
+			return PJ_TRUE;
+		}
+	}
+	return PJ_FALSE;
+}
+/*!
+ * \brief Called when a new SIP request comes into PJSIP
+ *
+ * This function is called under two circumstances
+ * 1) An out-of-dialog request is received by PJSIP
+ * 2) An in-dialog request that the inv_session layer does not
+ *    handle is received (such as an in-dialog INFO)
+ *
+ * In all cases, there is very little we actually do in this function
+ * 1) For requests we don't handle, we return PJ_FALSE
+ * 2) For new INVITEs, throw the work into the SIP threadpool to be done
+ *    there to free up the thread(s) handling incoming requests
+ * 3) For in-dialog requests we handle, we defer handling them until the
+ *    on_inv_state_change() callback instead (where we will end up putting
+ *    them into the threadpool).
+ */
+static pj_bool_t session_on_rx_request(pjsip_rx_data *rdata)
+{
+	pj_status_t handled = PJ_FALSE;
+	pjsip_dialog *dlg = pjsip_rdata_get_dlg(rdata);
+	pjsip_inv_session *inv_session;
+
+	switch (rdata->msg_info.msg->line.req.method.id) {
+	case PJSIP_INVITE_METHOD:
+		if (dlg) {
+			ast_log(LOG_WARNING, "on_rx_request called for INVITE in mid-dialog?\n");
+			break;
+		}
+		handled = PJ_TRUE;
+		handle_new_invite_request(rdata);
+		break;
+	default:
+		/* Handle other in-dialog methods if their supplements have been registered */
+		handled = dlg && (inv_session = pjsip_dlg_get_inv_session(dlg)) &&
+			has_supplement(inv_session->mod_data[session_module.id], rdata);
+		break;
+	}
+
+	return handled;
+}
+
+struct reschedule_reinvite_data {
+	struct ast_sip_session *session;
+	struct ast_sip_session_delayed_request *delay;
+};
+
+static struct reschedule_reinvite_data *reschedule_reinvite_data_alloc(
+		struct ast_sip_session *session, struct ast_sip_session_delayed_request *delay)
+{
+	struct reschedule_reinvite_data *rrd = ast_malloc(sizeof(*rrd));
+	if (!rrd) {
+		return NULL;
+	}
+	ao2_ref(session, +1);
+	rrd->session = session;
+	rrd->delay = delay;
+	return rrd;
+}
+
+static void reschedule_reinvite_data_destroy(struct reschedule_reinvite_data *rrd)
+{
+	ao2_cleanup(rrd->session);
+	ast_free(rrd->delay);
+	ast_free(rrd);
+}
+
+static int really_resend_reinvite(void *data)
+{
+	RAII_VAR(struct reschedule_reinvite_data *, rrd, data, reschedule_reinvite_data_destroy);
+
+	return send_delayed_request(rrd->session, rrd->delay);
+}
+
+static void resend_reinvite(pj_timer_heap_t *timer, pj_timer_entry *entry)
+{
+	struct reschedule_reinvite_data *rrd = entry->user_data;
+
+	ast_sip_push_task(rrd->session->serializer, really_resend_reinvite, entry->user_data);
+}
+
+static void reschedule_reinvite(struct ast_sip_session *session, ast_sip_session_response_cb on_response, pjsip_tx_data *tdata)
+{
+	struct ast_sip_session_delayed_request *delay = delayed_request_alloc("INVITE",
+			NULL, NULL, on_response, tdata);
+	pjsip_inv_session *inv = session->inv_session;
+	struct reschedule_reinvite_data *rrd = reschedule_reinvite_data_alloc(session, delay);
+	pj_time_val tv;
+	
+	if (!rrd || !delay) {
+		return;
+	}
+
+	tv.sec = 0;
+	if (inv->role == PJSIP_ROLE_UAC) {
+		tv.msec = 2100 + ast_random() % 2000;
+	} else {
+		tv.msec = ast_random() % 2000;
+	}
+
+	pj_timer_entry_init(&session->rescheduled_reinvite, 0, rrd, resend_reinvite);
+
+	pjsip_endpt_schedule_timer(ast_sip_get_pjsip_endpoint(), &session->rescheduled_reinvite, &tv);
+}
+
+static void __print_debug_details(const char *function, pjsip_inv_session *inv, pjsip_transaction *tsx, pjsip_event *e)
+{
+	struct ast_sip_session *session;
+	ast_debug(5, "Function %s called on event %s\n", function, pjsip_event_str(e->type));
+	if (!inv) {
+		ast_debug(5, "Transaction %p does not belong to an inv_session?\n", tsx);
+		ast_debug(5, "The transaction state is %s\n", pjsip_tsx_state_str(tsx->state));
+		return;
+	}
+	session = inv->mod_data[session_module.id];
+	if (!session) {
+		ast_debug(5, "inv_session %p has no ast session\n", inv);
+	} else {
+		ast_debug(5, "The state change pertains to the session with %s\n",
+				ast_sorcery_object_get_id(session->endpoint));
+	}
+	if (inv->invite_tsx) {
+		ast_debug(5, "The inv session still has an invite_tsx (%p)\n", inv->invite_tsx);
+	} else {
+		ast_debug(5, "The inv session does NOT have an invite_tsx\n");
+	}
+	if (tsx) {
+		ast_debug(5, "The transaction involved in this state change is %p\n", tsx);
+		ast_debug(5, "The current transaction state is %s\n", pjsip_tsx_state_str(tsx->state));
+		ast_debug(5, "The transaction state change event is %s\n", pjsip_event_str(e->body.tsx_state.type));
+	} else {
+		ast_debug(5, "There is no transaction involved in this state change\n");
+	}
+	ast_debug(5, "The current inv state is %s\n", pjsip_inv_state_name(inv->state));
+}
+
+#define print_debug_details(inv, tsx, e) __print_debug_details(__PRETTY_FUNCTION__, (inv), (tsx), (e))
+
+static void handle_incoming_request(struct ast_sip_session *session, pjsip_rx_data *rdata)
+{
+	struct ast_sip_session_supplement *supplement;
+	struct pjsip_request_line req = rdata->msg_info.msg->line.req;
+
+	ast_debug(3, "Method is %.*s\n", (int) pj_strlen(&req.method.name), pj_strbuf(&req.method.name));
+	AST_LIST_TRAVERSE(&session->supplements, supplement, next) {
+		if (supplement->incoming_request && does_method_match(&req.method.name, supplement->method)) {
+			if (supplement->incoming_request(session, rdata)) {
+				break;
+			}
+		}
+	}
+}
+
+static void handle_incoming_response(struct ast_sip_session *session, pjsip_rx_data *rdata)
+{
+	struct ast_sip_session_supplement *supplement;
+	struct pjsip_status_line status = rdata->msg_info.msg->line.status;
+
+	ast_debug(3, "Response is %d %.*s\n", status.code, (int) pj_strlen(&status.reason),
+			pj_strbuf(&status.reason));
+
+	AST_LIST_TRAVERSE(&session->supplements, supplement, next) {
+		if (supplement->incoming_response && does_method_match(&rdata->msg_info.cseq->method.name, supplement->method)) {
+			supplement->incoming_response(session, rdata);
+		}
+	}
+}
+
+static int handle_incoming(struct ast_sip_session *session, pjsip_rx_data *rdata)
+{
+	ast_debug(3, "Received %s\n", rdata->msg_info.msg->type == PJSIP_REQUEST_MSG ?
+			"request" : "response");
+
+	if (rdata->msg_info.msg->type == PJSIP_REQUEST_MSG) {
+		handle_incoming_request(session, rdata);
+	} else {
+		handle_incoming_response(session, rdata);
+	}
+
+	return 0;
+}
+
+static void handle_outgoing_request(struct ast_sip_session *session, pjsip_tx_data *tdata)
+{
+	struct ast_sip_session_supplement *supplement;
+	struct pjsip_request_line req = tdata->msg->line.req;
+
+	ast_debug(3, "Method is %.*s\n", (int) pj_strlen(&req.method.name), pj_strbuf(&req.method.name));
+	AST_LIST_TRAVERSE(&session->supplements, supplement, next) {
+		if (supplement->outgoing_request && does_method_match(&req.method.name, supplement->method)) {
+			supplement->outgoing_request(session, tdata);
+		}
+	}
+}
+
+static void handle_outgoing_response(struct ast_sip_session *session, pjsip_tx_data *tdata)
+{
+	struct ast_sip_session_supplement *supplement;
+	struct pjsip_status_line status = tdata->msg->line.status;
+	pjsip_cseq_hdr *cseq = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_CSEQ, NULL);
+	ast_debug(3, "Method is %.*s, Response is %d %.*s\n", (int) pj_strlen(&cseq->method.name),
+		pj_strbuf(&cseq->method.name), status.code, (int) pj_strlen(&status.reason),
+		pj_strbuf(&status.reason));
+
+	AST_LIST_TRAVERSE(&session->supplements, supplement, next) {
+		if (supplement->outgoing_response && does_method_match(&cseq->method.name, supplement->method)) {
+			supplement->outgoing_response(session, tdata);
+		}
+	}
+}
+
+static void handle_outgoing(struct ast_sip_session *session, pjsip_tx_data *tdata)
+{
+	ast_debug(3, "Sending %s\n", tdata->msg->type == PJSIP_REQUEST_MSG ?
+			"request" : "response");
+	if (tdata->msg->type == PJSIP_REQUEST_MSG) {
+		handle_outgoing_request(session, tdata);
+	} else {
+		handle_outgoing_response(session, tdata);
+	}
+}
+
+static int session_end(struct ast_sip_session *session)
+{
+	struct ast_sip_session_supplement *iter;
+
+	/* Stop the scheduled termination */
+	if (pj_timer_heap_cancel(pjsip_endpt_get_timer_heap(ast_sip_get_pjsip_endpoint()), &session->scheduled_termination)) {
+		ao2_ref(session, -1);
+	}
+
+	/* Session is dead. Let's get rid of the reference to the session */
+	AST_LIST_TRAVERSE(&session->supplements, iter, next) {
+		if (iter->session_end) {
+			iter->session_end(session);
+		}
+	}
+
+	session->inv_session->mod_data[session_module.id] = NULL;
+	ast_sip_dialog_set_serializer(session->inv_session->dlg, NULL);
+	ast_sip_dialog_set_endpoint(session->inv_session->dlg, NULL);
+	ao2_cleanup(session);
+	return 0;
+}
+
+static void session_inv_on_state_changed(pjsip_inv_session *inv, pjsip_event *e)
+{
+	struct ast_sip_session *session = inv->mod_data[session_module.id];
+
+	print_debug_details(inv, NULL, e);
+
+	switch(e->type) {
+	case PJSIP_EVENT_TX_MSG:
+		handle_outgoing(session, e->body.tx_msg.tdata);
+		break;
+	case PJSIP_EVENT_RX_MSG:
+		handle_incoming(session, e->body.rx_msg.rdata);
+		break;
+	case PJSIP_EVENT_TSX_STATE:
+		ast_debug(3, "Source of transaction state change is %s\n", pjsip_event_str(e->body.tsx_state.type));
+		/* Transaction state changes are prompted by some other underlying event. */
+		switch(e->body.tsx_state.type) {
+		case PJSIP_EVENT_TX_MSG:
+			handle_outgoing(session, e->body.tsx_state.src.tdata);
+			break;
+		case PJSIP_EVENT_RX_MSG:
+			handle_incoming(session, e->body.tsx_state.src.rdata);
+			break;
+		case PJSIP_EVENT_TRANSPORT_ERROR:
+		case PJSIP_EVENT_TIMER:
+		case PJSIP_EVENT_USER:
+		case PJSIP_EVENT_UNKNOWN:
+		case PJSIP_EVENT_TSX_STATE:
+			/* Inception? */
+			break;
+		}
+		break;
+	case PJSIP_EVENT_TRANSPORT_ERROR:
+	case PJSIP_EVENT_TIMER:
+	case PJSIP_EVENT_UNKNOWN:
+	case PJSIP_EVENT_USER:
+	default:
+		break;
+	}
+
+	if (inv->state == PJSIP_INV_STATE_DISCONNECTED) {
+		session_end(session);
+	}
+}
+
+static void session_inv_on_new_session(pjsip_inv_session *inv, pjsip_event *e)
+{
+	/* XXX STUB */
+}
+
+static void session_inv_on_tsx_state_changed(pjsip_inv_session *inv, pjsip_transaction *tsx, pjsip_event *e)
+{
+	struct ast_sip_session *session = inv->mod_data[session_module.id];
+	print_debug_details(inv, tsx, e);
+	if (!session) {
+		/* Transaction likely timed out after the call was hung up. Just
+		 * ignore such transaction changes
+		 */
+		return;
+	}
+	switch (e->body.tsx_state.type) {
+	case PJSIP_EVENT_TX_MSG:
+		/* When we create an outgoing request, we do not have access to the transaction that
+		 * is created. Instead, We have to place transaction-specific data in the tdata. Here,
+		 * we transfer the data into the transaction. This way, when we receive a response, we
+		 * can dig this data out again
+		 */
+		tsx->mod_data[session_module.id] = e->body.tsx_state.src.tdata->mod_data[session_module.id];
+		break;
+	case PJSIP_EVENT_RX_MSG:
+		if (tsx->method.id == PJSIP_INVITE_METHOD) {
+			if (tsx->role == PJSIP_ROLE_UAC && tsx->state == PJSIP_TSX_STATE_COMPLETED) {
+				/* This means we got a non 2XX final response to our outgoing INVITE */
+				if (tsx->status_code == PJSIP_SC_REQUEST_PENDING) {
+					reschedule_reinvite(session, tsx->mod_data[session_module.id], tsx->last_tx);
+					return;
+				} else if (inv->state == PJSIP_INV_STATE_CONFIRMED &&
+					   tsx->status_code != 488) {
+					/* Other reinvite failures (except 488) result in destroying the session. */
+					pjsip_tx_data *tdata;
+					if (pjsip_inv_end_session(inv, 500, NULL, &tdata) == PJ_SUCCESS) {
+						ast_sip_session_send_request(session, tdata);
+					}
+				}
+			}
+		} else {
+			if (tsx->role == PJSIP_ROLE_UAS && tsx->state == PJSIP_TSX_STATE_TRYING) {
+				handle_incoming_request(session, e->body.tsx_state.src.rdata);
+			}
+		}
+		if (tsx->mod_data[session_module.id]) {
+			ast_sip_session_response_cb cb = tsx->mod_data[session_module.id];
+			cb(session, e->body.tsx_state.src.rdata);
+		}
+	case PJSIP_EVENT_TRANSPORT_ERROR:
+	case PJSIP_EVENT_TIMER:
+	case PJSIP_EVENT_USER:
+	case PJSIP_EVENT_UNKNOWN:
+	case PJSIP_EVENT_TSX_STATE:
+		/* Inception? */
+		break;
+	}
+
+	/* Terminated INVITE transactions always should result in queuing delayed requests,
+	 * no matter what event caused the transaction to terminate
+	 */
+	if (tsx->method.id == PJSIP_INVITE_METHOD && tsx->state == PJSIP_TSX_STATE_TERMINATED) {
+		queue_delayed_request(session);
+	}
+}
+
+static int add_sdp_streams(void *obj, void *arg, void *data, int flags)
+{
+	struct ast_sip_session_media *session_media = obj;
+	pjmedia_sdp_session *answer = arg;
+	struct ast_sip_session *session = data;
+	struct ast_sip_session_sdp_handler *handler = session_media->handler;
+	RAII_VAR(struct sdp_handler_list *, handler_list, NULL, ao2_cleanup);
+
+	if (handler) {
+		/* if an already assigned handler does not handle the session_media or reports a catastrophic error, fail */
+		if (handler->create_outgoing_sdp_stream(session, session_media, answer) <= 0) {
+			return 0;
+		}
+		return CMP_MATCH;
+	}
+
+	handler_list = ao2_find(sdp_handlers, session_media->stream_type, OBJ_KEY);
+	if (!handler_list) {
+		return CMP_MATCH;
+	}
+
+	/* no handler for this stream type and we have a list to search */
+	AST_LIST_TRAVERSE(&handler_list->list, handler, next) {
+		int res = handler->create_outgoing_sdp_stream(session, session_media, answer);
+		if (res < 0) {
+			/* catastrophic error */
+			return 0;
+		}
+		if (res > 0) {
+			/* handled */
+			return CMP_MATCH;
+		}
+	}
+
+	/* streams that weren't handled won't be included in generated outbound SDP */
+	return CMP_MATCH;
+}
+
+static struct pjmedia_sdp_session *create_local_sdp(pjsip_inv_session *inv, struct ast_sip_session *session, const pjmedia_sdp_session *offer)
+{
+	RAII_VAR(struct ao2_iterator *, successful, NULL, ao2_iterator_cleanup);
+	static const pj_str_t STR_IN = { "IN", 2 };
+	static const pj_str_t STR_IP4 = { "IP4", 3 };
+	static const pj_str_t STR_IP6 = { "IP6", 3 };
+	pjmedia_sdp_session *local;
+
+	if (!(local = PJ_POOL_ZALLOC_T(inv->pool_prov, pjmedia_sdp_session))) {
+		return NULL;
+	}
+
+	if (!offer) {
+		local->origin.version = local->origin.id = (pj_uint32_t)(ast_random());
+	} else {
+		local->origin.version = offer->origin.version + 1;
+		local->origin.id = offer->origin.id;
+	}
+
+	pj_strdup2(inv->pool, &local->origin.user, session->endpoint->media.sdpowner);
+	local->origin.net_type = STR_IN;
+	local->origin.addr_type = session->endpoint->media.rtp.ipv6 ? STR_IP6 : STR_IP4;
+	local->origin.addr = *pj_gethostname();
+	pj_strdup2(inv->pool, &local->name, session->endpoint->media.sdpsession);
+
+	/* Now let the handlers add streams of various types, pjmedia will automatically reorder the media streams for us */
+	successful = ao2_callback_data(session->media, OBJ_MULTIPLE, add_sdp_streams, local, session);
+	if (!successful || ao2_container_count(successful->c) != ao2_container_count(session->media)) {
+		/* Something experienced a catastrophic failure */
+		return NULL;
+	}
+
+	/* Use the connection details of the first media stream if possible for SDP level */
+	if (local->media_count) {
+		local->conn = local->media[0]->conn;
+	}
+
+	return local;
+}
+
+static void session_inv_on_rx_offer(pjsip_inv_session *inv, const pjmedia_sdp_session *offer)
+{
+	struct ast_sip_session *session = inv->mod_data[session_module.id];
+	pjmedia_sdp_session *answer;
+
+	if (handle_incoming_sdp(session, offer)) {
+		return;
+	}
+
+	if ((answer = create_local_sdp(inv, session, offer))) {
+		pjsip_inv_set_sdp_answer(inv, answer);
+	}
+}
+
+#if 0
+static void session_inv_on_create_offer(pjsip_inv_session *inv, pjmedia_sdp_session **p_offer)
+{
+	/* XXX STUB */
+}
+#endif
+
+static void session_inv_on_media_update(pjsip_inv_session *inv, pj_status_t status)
+{
+	struct ast_sip_session *session = inv->mod_data[session_module.id];
+	const pjmedia_sdp_session *local, *remote;
+
+	if (!session->channel) {
+		/* If we don't have a channel. We really don't care about media updates.
+		 * Just ignore
+		 */
+		return;
+	}
+
+	if ((status != PJ_SUCCESS) || (pjmedia_sdp_neg_get_active_local(inv->neg, &local) != PJ_SUCCESS) ||
+		(pjmedia_sdp_neg_get_active_remote(inv->neg, &remote) != PJ_SUCCESS)) {
+		ast_channel_hangupcause_set(session->channel, AST_CAUSE_BEARERCAPABILITY_NOTAVAIL);
+		ast_queue_hangup(session->channel);
+		return;
+	}
+
+	handle_negotiated_sdp(session, local, remote);
+}
+
+static pjsip_redirect_op session_inv_on_redirected(pjsip_inv_session *inv, const pjsip_uri *target, const pjsip_event *e)
+{
+	struct ast_sip_session *session = inv->mod_data[session_module.id];
+
+	if (PJSIP_URI_SCHEME_IS_SIP(target) || PJSIP_URI_SCHEME_IS_SIPS(target)) {
+		const pjsip_sip_uri *uri = pjsip_uri_get_uri(target);
+		char exten[AST_MAX_EXTENSION];
+
+		ast_copy_pj_str(exten, &uri->user, sizeof(exten));
+		ast_channel_call_forward_set(session->channel, exten);
+	}
+
+	return PJSIP_REDIRECT_STOP;
+}
+
+static pjsip_inv_callback inv_callback = {
+	.on_state_changed = session_inv_on_state_changed,
+	.on_new_session = session_inv_on_new_session,
+	.on_tsx_state_changed = session_inv_on_tsx_state_changed,
+	.on_rx_offer = session_inv_on_rx_offer,
+	.on_media_update = session_inv_on_media_update,
+	.on_redirected = session_inv_on_redirected,
+};
+
+/*! \brief Hook for modifying outgoing messages with SDP to contain the proper address information */
+static void session_outgoing_nat_hook(pjsip_tx_data *tdata, struct ast_sip_transport *transport)
+{
+	struct ast_sip_nat_hook *hook = tdata->mod_data[session_module.id];
+	struct pjmedia_sdp_session *sdp;
+	int stream;
+
+	/* SDP produced by us directly will never be multipart */
+	if (hook || !tdata->msg->body || pj_stricmp2(&tdata->msg->body->content_type.type, "application") ||
+		pj_stricmp2(&tdata->msg->body->content_type.subtype, "sdp") || ast_strlen_zero(transport->external_media_address)) {
+		return;
+	}
+
+	sdp = tdata->msg->body->data;
+
+	for (stream = 0; stream < sdp->media_count; ++stream) {
+		/* See if there are registered handlers for this media stream type */
+		char media[20];
+		struct ast_sip_session_sdp_handler *handler;
+		RAII_VAR(struct sdp_handler_list *, handler_list, NULL, ao2_cleanup);
+
+		/* We need a null-terminated version of the media string */
+		ast_copy_pj_str(media, &sdp->media[stream]->desc.media, sizeof(media));
+
+		handler_list = ao2_find(sdp_handlers, media, OBJ_KEY);
+		if (!handler_list) {
+			ast_debug(1, "No registered SDP handlers for media type '%s'\n", media);
+			continue;
+		}
+		AST_LIST_TRAVERSE(&handler_list->list, handler, next) {
+			if (handler->change_outgoing_sdp_stream_media_address) {
+				handler->change_outgoing_sdp_stream_media_address(tdata, sdp->media[stream], transport);
+			}
+		}
+	}
+
+	/* We purposely do this so that the hook will not be invoked multiple times, ie: if a retransmit occurs */
+	tdata->mod_data[session_module.id] = nat_hook;
+}
+
+static int load_module(void)
+{
+	pjsip_endpoint *endpt;
+	if (!ast_sip_get_sorcery() || !ast_sip_get_pjsip_endpoint()) {
+		return AST_MODULE_LOAD_DECLINE;
+	}
+	if (!(nat_hook = ast_sorcery_alloc(ast_sip_get_sorcery(), "nat_hook", NULL))) {
+		return AST_MODULE_LOAD_DECLINE;
+	}
+	nat_hook->outgoing_external_message = session_outgoing_nat_hook;
+	ast_sorcery_create(ast_sip_get_sorcery(), nat_hook);
+	sdp_handlers = ao2_container_alloc(SDP_HANDLER_BUCKETS,
+			sdp_handler_list_hash, sdp_handler_list_cmp);
+	if (!sdp_handlers) {
+		return AST_MODULE_LOAD_DECLINE;
+	}
+	endpt = ast_sip_get_pjsip_endpoint();
+	pjsip_inv_usage_init(endpt, &inv_callback);
+	pjsip_100rel_init_module(endpt);
+	pjsip_timer_init_module(endpt);
+	if (ast_sip_register_service(&session_module)) {
+		return AST_MODULE_LOAD_DECLINE;
+	}
+	ast_sip_register_service(&session_reinvite_module);
+	return AST_MODULE_LOAD_SUCCESS;
+}
+
+static int unload_module(void)
+{
+	ast_sip_unregister_service(&session_module);
+	ast_sip_unregister_service(&session_reinvite_module);
+	if (nat_hook) {
+		ast_sorcery_delete(ast_sip_get_sorcery(), nat_hook);
+		nat_hook = NULL;
+	}
+	return 0;
+}
+
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS | AST_MODFLAG_LOAD_ORDER, "PJSIP Session resource",
+		.load = load_module,
+		.unload = unload_module,
+		.load_pri = AST_MODPRI_APP_DEPEND,
+	       );