Basic module, transport, and sending messages

git-svn-id: http://svn.pjsip.org/repos/pjproject/trunk@106 74dad513-b988-da41-8d7b-12977e46ad98

8 files changed, 413 insertions, 143 deletions

diff --git a/pjsip/include/pjsip/sip_endpoint.h b/pjsip/include/pjsip/sip_endpoint.h
index 8254d508..d9d03a97 100644
--- a/pjsip/include/pjsip/sip_endpoint.h
+++ b/pjsip/include/pjsip/sip_endpoint.h
@@ -115,6 +115,34 @@ PJ_DECL(const pj_str_t*) pjsip_endpt_name(const pjsip_endpoint *endpt);
 PJ_DECL(void) pjsip_endpt_handle_events( pjsip_endpoint *endpt, 
 					 const pj_time_val *max_timeout);
 
+
+/**
+ * Schedule timer to endpoint's timer heap. Application must poll the endpoint
+ * periodically (by calling #pjsip_endpt_handle_events) to ensure that the
+ * timer events are handled in timely manner. When the timeout for the timer
+ * has elapsed, the callback specified in the entry argument will be called.
+ * This function, like all other endpoint functions, is thread safe.
+ *
+ * @param endpt	    The endpoint.
+ * @param entry	    The timer entry.
+ * @param delay	    The relative delay of the timer.
+ * @return	    PJ_OK (zero) if successfull.
+ */
+PJ_DECL(pj_status_t) pjsip_endpt_schedule_timer( pjsip_endpoint *endpt,
+						 pj_timer_entry *entry,
+						 const pj_time_val *delay );
+
+/**
+ * Cancel the previously registered timer.
+ * This function, like all other endpoint functions, is thread safe.
+ *
+ * @param endpt	    The endpoint.
+ * @param entry	    The timer entry previously registered.
+ */
+PJ_DECL(void) pjsip_endpt_cancel_timer( pjsip_endpoint *endpt, 
+					pj_timer_entry *entry );
+
+
 /**
  * Dump endpoint status to the log. This will print the status to the log
  * with log level 3.
@@ -126,6 +154,35 @@ PJ_DECL(void) pjsip_endpt_handle_events( pjsip_endpoint *endpt,
  */
 PJ_DECL(void) pjsip_endpt_dump( pjsip_endpoint *endpt, pj_bool_t detail );
 
+
+/**
+ * Register new module to the endpoint.
+ * The endpoint will then call the load and start function in the module to 
+ * properly initialize the module, and assign a unique module ID for the 
+ * module.
+ *
+ * @param endpt		The endpoint.
+ * @param module	The module to be registered.
+ *
+ * @return		PJ_SUCCESS on success.
+ */
+PJ_DECL(pj_status_t) pjsip_endpt_register_module( pjsip_endpoint *endpt,
+						  pjsip_module *module );
+
+/**
+ * Unregister a module from the endpoint.
+ * The endpoint will then call the stop and unload function in the module to 
+ * properly shutdown the module.
+ *
+ * @param endpt		The endpoint.
+ * @param module	The module to be registered.
+ *
+ * @return		PJ_SUCCESS on success.
+ */
+PJ_DECL(pj_status_t) pjsip_endpt_unregister_module( pjsip_endpoint *endpt,
+						    pjsip_module *module );
+
+
 /**
  * Create pool from the endpoint. All SIP components should allocate their
  * memory pool by calling this function, to make sure that the pools are
@@ -156,32 +213,6 @@ PJ_DECL(void) pjsip_endpt_destroy_pool( pjsip_endpoint *endpt,
 					pj_pool_t *pool );
 
 /**
- * Schedule timer to endpoint's timer heap. Application must poll the endpoint
- * periodically (by calling #pjsip_endpt_handle_events) to ensure that the
- * timer events are handled in timely manner. When the timeout for the timer
- * has elapsed, the callback specified in the entry argument will be called.
- * This function, like all other endpoint functions, is thread safe.
- *
- * @param endpt	    The endpoint.
- * @param entry	    The timer entry.
- * @param delay	    The relative delay of the timer.
- * @return	    PJ_OK (zero) if successfull.
- */
-PJ_DECL(pj_status_t) pjsip_endpt_schedule_timer( pjsip_endpoint *endpt,
-						 pj_timer_entry *entry,
-						 const pj_time_val *delay );
-
-/**
- * Cancel the previously registered timer.
- * This function, like all other endpoint functions, is thread safe.
- *
- * @param endpt	    The endpoint.
- * @param entry	    The timer entry previously registered.
- */
-PJ_DECL(void) pjsip_endpt_cancel_timer( pjsip_endpoint *endpt, 
-					pj_timer_entry *entry );
-
-/**
  * Create a new transaction. After creating the transaction, application MUST
  * initialize the transaction as either UAC or UAS (by calling
  * #pjsip_tsx_init_uac or #pjsip_tsx_init_uas), then must register the 
@@ -278,11 +309,12 @@ PJ_DECL(pj_ioqueue_t*) pjsip_endpt_get_ioqueue(pjsip_endpoint *endpt);
  *
  * @see pjsip_transport_get
  */
-PJ_DECL(pj_status_t) pjsip_endpt_alloc_transport( pjsip_endpoint *endpt,
-						  pjsip_transport_type_e type,
-						  const pj_sockaddr *remote,
-						  int addr_len,
-						  pjsip_transport **p_transport);
+PJ_DECL(pj_status_t) 
+pjsip_endpt_acquire_transport( pjsip_endpoint *endpt,
+			       pjsip_transport_type_e type,
+			       const pj_sockaddr_t *remote,
+			       int addr_len,
+			       pjsip_transport **p_transport);
 
 /**
  * Get additional headers to be put in outgoing request message. 
diff --git a/pjsip/include/pjsip/sip_errno.h b/pjsip/include/pjsip/sip_errno.h
index eefda673..4d50c75d 100644
--- a/pjsip/include/pjsip/sip_errno.h
+++ b/pjsip/include/pjsip/sip_errno.h
@@ -93,7 +93,7 @@ PJ_DECL(pj_str_t) pjsip_strerror( pj_status_t status, char *buffer,
  ***********************************************************/
 /**
  * @hideinitializer
- * Invalid message (syntax error)
+ * General invalid message error (e.g. syntax error)
  */
 #define PJSIP_EINVALIDMSG       (PJSIP_ERRNO_START_PJSIP + 20)	/* 171020 */
 /**
@@ -113,19 +113,45 @@ PJ_DECL(pj_str_t) pjsip_strerror( pj_status_t status, char *buffer,
 #define PJSIP_EPARTIALMSG       (PJSIP_ERRNO_START_PJSIP + 23)	/* 171023 */
 /**
  * @hideinitializer
+ * Missing Request-URI.
+ */
+#define PJSIP_EMISSINGREQURI    (PJSIP_ERRNO_START_PJSIP + 24)	/* 171024 */
+/**
+ * @hideinitializer
  * Missing required header(s).
  */
-#define PJSIP_EMISSINGHDR       (PJSIP_ERRNO_START_PJSIP + 24)	/* 171024 */
+#define PJSIP_EMISSINGHDR       (PJSIP_ERRNO_START_PJSIP + 25)	/* 171025 */
+/**
+ * @hideinitializer
+ * Missing message body.
+ */
+#define PJSIP_EMISSINGBODY	(PJSIP_ERRNO_START_PJSIP + 26)	/* 171026 */
 /**
  * @hideinitializer
  * Invalid Via header in response (sent-by, etc).
  */
-#define PJSIP_EINVALIDVIA	(PJSIP_ERRNO_START_PJSIP + 25)	/* 171025 */
+#define PJSIP_EINVALIDVIA	(PJSIP_ERRNO_START_PJSIP + 27)	/* 171027 */
 /**
  * @hideinitializer
  * Multiple Via headers in response.
  */
-#define PJSIP_EMULTIPLEVIA	(PJSIP_ERRNO_START_PJSIP + 26)	/* 171026 */
+#define PJSIP_EMULTIPLEVIA	(PJSIP_ERRNO_START_PJSIP + 28)	/* 171028 */
+/**
+ * @hideinitializer
+ * Invalid request URI.
+ */
+#define PJSIP_EINVALIDREQURI	(PJSIP_ERRNO_START_PJSIP + 29)	/* 171029 */
+/**
+ * @hideinitializer
+ * Expecting request message.
+ */
+#define PJSIP_ENOTREQUESTMSG	(PJSIP_ERRNO_START_PJSIP + 30)	/* 171030 */
+/**
+ * @hideinitializer
+ * Expecting response message.
+ */
+#define PJSIP_ENOTRESPONSEMSG	(PJSIP_ERRNO_START_PJSIP + 31)	/* 171031 */
+
 
 /************************************************************
  * TRANSPORT ERRORS
@@ -144,7 +170,13 @@ PJ_DECL(pj_str_t) pjsip_strerror( pj_status_t status, char *buffer,
  * @hideinitializer
  * Rx buffer overflow. See also PJSIP_EMSGTOOLONG.
  */
-#define PJSIP_ERXOVERFLOW         (PJSIP_ERRNO_START_PJSIP + 42)/* 171042 */
+#define PJSIP_ERXOVERFLOW       (PJSIP_ERRNO_START_PJSIP + 42)	/* 171042 */
+/**
+ * @hideinitializer
+ * This is not really an error, it just informs application that
+ * transmit data has been deleted on return of pjsip_tx_data_dec_ref().
+ */
+#define PJSIP_EBUFDESTROYED     (PJSIP_ERRNO_START_PJSIP + 43)	/* 171043 */
 
 
 /************************************************************
diff --git a/pjsip/include/pjsip/sip_module.h b/pjsip/include/pjsip/sip_module.h
index 345be88a..0f188194 100644
--- a/pjsip/include/pjsip/sip_module.h
+++ b/pjsip/include/pjsip/sip_module.h
@@ -41,28 +41,31 @@ PJ_BEGIN_DECL
  */
 struct pjsip_module
 {
+    /** To allow chaining of modules in the endpoint. */
+    PJ_DECL_LIST_MEMBER(struct pjsip_module);
+
     /**
      * Module name.
      */
     pj_str_t name;
 
     /**
-     * Flag to indicate the type of interfaces supported by the module.
+     * Module ID.
      */
-    pj_uint32_t flag;
+    int id;
 
     /**
      * Integer number to identify module initialization and start order with
      * regard to other modules. Higher number will make the module gets
      * initialized later.
      */
-    pj_uint32_t priority;
+    int priority;
 
     /**
      * Opaque data which can be used by a module to identify a resource within
      * the module itself.
      */
-    void *mod_data;
+    void *user_data;
 
     /**
      * Number of methods supported by this module.
@@ -78,22 +81,24 @@ struct pjsip_module
      * Pointer to function to be called to initialize the module.
      *
      * @param endpt	The endpoint instance.
-     * @param mod	The module.
-     * @param id	The unique module ID assigned to this module.
-     *
-     * @return		Module should return zero when initialization succeed.
+     * @return		Module should return PJ_SUCCESS to indicate success.
      */
-    pj_status_t (*init_module)(pjsip_endpoint *endpt,
-			       struct pjsip_module *mod, pj_uint32_t id);
+    pj_status_t (*load)(pjsip_endpoint *endpt);
 
     /**
      * Pointer to function to be called to start the module.
      *
-     * @param mod	The module.
-     *
      * @return		Module should return zero to indicate success.
      */
-    pj_status_t (*start_module)(struct pjsip_module *mod);
+    pj_status_t (*start)(void);
+
+    /**
+     * Pointer to function to be called to deinitialize the module before
+     * it is unloaded.
+     *
+     * @return		Module should return PJ_SUCCESS to indicate success.
+     */
+    pj_status_t (*stop)(void);
 
     /**
      * Pointer to function to be called to deinitialize the module before
@@ -101,34 +106,55 @@ struct pjsip_module
      *
      * @param mod	The module.
      *
-     * @return		Module should return zero to indicate success.
+     * @return		Module should return PJ_SUCCESS to indicate success.
      */
-    pj_status_t (*deinit_module)(struct pjsip_module *mod);
+    pj_status_t (*unload)(void);
 
     /**
-     * Pointer to function to receive transaction related events.
-     * If the module doesn't wish to receive such notification, this member
-     * must be set to NULL.
+     * Called to process incoming request.
      *
-     * @param mod	The module.
-     * @param event	The transaction event.
+     * @param rdata	The incoming message.
+     *
+     * @return		Module should return PJ_TRUE if it handles the request,
+     *			or otherwise it should return PJ_FALSE to allow other
+     *			modules to handle the request.
      */
-    void (*tsx_handler)(struct pjsip_module *mod, pjsip_event *event);
+    pj_bool_t (*on_rx_request)(pjsip_rx_data *rdata);
+
+    /**
+     * Called to processed incoming response.
+     *
+     * @param rdata	The incoming message.
+     *
+     * @return		Module should return PJ_TRUE if it handles the 
+     *			response, or otherwise it should return PJ_FALSE to 
+     *			allow other modules to handle the response.
+     */
+    pj_bool_t (*on_rx_response)(pjsip_rx_data *rdata);
+
+    /**
+     * Called when this module is acting as transaction user for the specified
+     * transaction, when the transaction's state has changed.
+     *
+     * @param tsx	The transaction.
+     * @param event	The event which has caused the transaction state
+     *			to change.
+     */
+    void (*on_tsx_state)(pjsip_transaction *tsx, pjsip_event *event);
+
 };
 
 
 /**
- * Prototype of function to register static modules (eg modules that are
- * linked staticly with the application). This function must be implemented 
- * by any applications that use PJSIP library.
- *
- * @param count	    [input/output] On input, it contains the maximum number of
- *		    elements in the array. On output, the function fills with 
- *		    the number of modules to be registered.
- * @param modules   [output] array of pointer to modules to be registered.
+ * Module priority guidelines.
  */
-pj_status_t register_static_modules( pj_size_t *count,
-				     pjsip_module **modules );
+enum pjsip_module_priority
+{
+    PJSIP_MOD_PRIORITY_TSX_LAYER = 4,
+    PJSIP_MOD_PRIORITY_UA_PROXY_LAYER = 16,
+    PJSIP_MOD_PRIORITY_APPLICATION = 32,
+};
+
 
 /**
  * @}
diff --git a/pjsip/include/pjsip/sip_msg.h b/pjsip/include/pjsip/sip_msg.h
index 836ce37b..e1866048 100644
--- a/pjsip/include/pjsip/sip_msg.h
+++ b/pjsip/include/pjsip/sip_msg.h
@@ -52,27 +52,14 @@ PJ_BEGIN_DECL
  */
 typedef enum pjsip_method_e
 {
-    /** INVITE method, for establishing dialogs. */
-    PJSIP_INVITE_METHOD,
+    PJSIP_INVITE_METHOD,    /**< INVITE method, for establishing dialogs.   */
+    PJSIP_CANCEL_METHOD,    /**< CANCEL method, for cancelling request.	    */
+    PJSIP_ACK_METHOD,	    /**< ACK method.				    */
+    PJSIP_BYE_METHOD,	    /**< BYE method, for terminating dialog.	    */
+    PJSIP_REGISTER_METHOD,  /**< REGISTER method.			    */
+    PJSIP_OPTIONS_METHOD,   /**< OPTIONS method.			    */
 
-    /** CANCEL method, for cancelling request. */
-    PJSIP_CANCEL_METHOD,
-
-    /** ACK method, for acknowledging final response to INVITE. */
-    PJSIP_ACK_METHOD,
-
-    /** BYE method, for terminating dialog. */
-    PJSIP_BYE_METHOD,
-
-    /** REGISTER method. */
-    PJSIP_REGISTER_METHOD,
-
-    /** OPTIONS method, for querying remote capabilities. */
-    PJSIP_OPTIONS_METHOD,
-
-    /** Other method, which means that the method name itself will be stored
-        elsewhere. */
-    PJSIP_OTHER_METHOD,
+    PJSIP_OTHER_METHOD,	    /**< Other method.				    */
 
 } pjsip_method_e;
 
@@ -93,6 +80,17 @@ typedef struct pjsip_method
 } pjsip_method;
 
 
+/*
+ * For convenience, standard method structures are defined in the library.
+ */
+extern const pjsip_method pjsip_invite_method;	    /**< INVITE structure.  */
+extern const pjsip_method pjsip_cancel_method;	    /**< CANCEL structure.  */
+extern const pjsip_method pjsip_ack_method;	    /**< ACK structure.     */
+extern const pjsip_method pjsip_bye_method;	    /**< BYE structure.     */
+extern const pjsip_method pjsip_register_method;    /**< REGISTER structure.*/
+extern const pjsip_method pjsip_options_method;	    /**< OPTIONS structure. */
+
+
 /** 
  * Initialize the method structure from a string. 
  * This function will check whether the method is a known method then set
@@ -638,8 +636,8 @@ PJ_DECL(pjsip_msg*)  pjsip_msg_create( pj_pool_t *pool, pjsip_msg_type_e type);
  * @return	    The header field, or NULL if no header with the specified 
  *		    type is found.
  */
-PJ_DECL(void*)  pjsip_msg_find_hdr( pjsip_msg *msg, 
-				    pjsip_hdr_e type, void *start);
+PJ_DECL(void*)  pjsip_msg_find_hdr( const pjsip_msg *msg, 
+				    pjsip_hdr_e type, const void *start);
 
 /** 
  * Find a header in the message by its name.
@@ -654,8 +652,9 @@ PJ_DECL(void*)  pjsip_msg_find_hdr( pjsip_msg *msg,
  * @return	    The header field, or NULL if no header with the specified 
  *		    type is found.
  */
-PJ_DECL(void*)  pjsip_msg_find_hdr_by_name( pjsip_msg *msg, 
-					    const pj_str_t *name, void *start);
+PJ_DECL(void*)  pjsip_msg_find_hdr_by_name( const pjsip_msg *msg, 
+					    const pj_str_t *name, 
+					    const void *start);
 
 /** 
  * Find and remove a header in the message. 
@@ -702,7 +701,8 @@ PJ_IDECL(void) pjsip_msg_insert_first_hdr( pjsip_msg *msg, pjsip_hdr *hdr );
  * @return	The length of the printed characters (in bytes), or NEGATIVE
  *		value if the message is too large for the specified buffer.
  */
-PJ_DECL(pj_ssize_t) pjsip_msg_print(pjsip_msg *msg, char *buf, pj_size_t size);
+PJ_DECL(pj_ssize_t) pjsip_msg_print(const pjsip_msg *msg, 
+				    char *buf, pj_size_t size);
 
 /**
  * @}
diff --git a/pjsip/include/pjsip/sip_transport.h b/pjsip/include/pjsip/sip_transport.h
index 14175dc7..6e6ba428 100644
--- a/pjsip/include/pjsip/sip_transport.h
+++ b/pjsip/include/pjsip/sip_transport.h
@@ -367,16 +367,21 @@ PJ_DECL(void) pjsip_tx_data_add_ref( pjsip_tx_data *tdata );
 
 /**
  * Decrement reference counter of the transmit buffer.
- * When the transmit buffer is no longer used, it will be destroyed.
+ * When the transmit buffer is no longer used, it will be destroyed and
+ * caller is informed with PJSIP_EBUFDESTROYED return status.
  *
  * @param tdata	    The transmit buffer data.
+ * @return	    This function will always succeeded eventhough the return
+ *		    status is non-zero. A status PJSIP_EBUFDESTROYED will be
+ *		    returned to inform that buffer is destroyed.
  */
-PJ_DECL(void) pjsip_tx_data_dec_ref( pjsip_tx_data *tdata );
+PJ_DECL(pj_status_t) pjsip_tx_data_dec_ref( pjsip_tx_data *tdata );
 
 /**
  * Check if transmit data buffer contains a valid message.
  *
  * @param tdata	    The transmit buffer.
+ * @return	    Non-zero (PJ_TRUE) if buffer contains a valid message.
  */
 PJ_DECL(pj_bool_t) pjsip_tx_data_is_valid( pjsip_tx_data *tdata );
 
@@ -542,11 +547,14 @@ struct pjsip_tpfactory
 
     /**
      * Create new outbound connection.
+     * Note that the factory is responsible for both creating the
+     * transport and registering it to the transport manager.
      */
     pj_status_t (*create_transport)(pjsip_tpfactory *factory,
 				    pjsip_tpmgr *mgr,
 				    pjsip_endpoint *endpt,
 				    const pj_sockaddr *rem_addr,
+				    int addr_len,
 				    pjsip_transport **transport);
 
     /*
@@ -621,11 +629,11 @@ PJ_DECL(void) pjsip_tpmgr_dump_transports(pjsip_tpmgr *mgr);
  * Find transport to be used to send message to remote destination. If no
  * suitable transport is found, a new one will be created.
  */
-PJ_DECL(pj_status_t) pjsip_tpmgr_alloc_transport( pjsip_tpmgr *mgr,
-						  pjsip_transport_type_e type,
-						  const pj_sockaddr_t *remote,
-						  int addr_len,
-						  pjsip_transport **p_transport );
+PJ_DECL(pj_status_t) pjsip_tpmgr_acquire_transport(pjsip_tpmgr *mgr,
+						   pjsip_transport_type_e type,
+						   const pj_sockaddr_t *remote,
+						   int addr_len,
+						   pjsip_transport **tp);
 
 
 /**
diff --git a/pjsip/include/pjsip/sip_transport_udp.h b/pjsip/include/pjsip/sip_transport_udp.h
index d3fd5d30..886f18c6 100644
--- a/pjsip/include/pjsip/sip_transport_udp.h
+++ b/pjsip/include/pjsip/sip_transport_udp.h
@@ -21,7 +21,7 @@
 
 #include <pjsip/sip_transport.h>
 
-PJ_DECL
+PJ_BEGIN_DECL
 
 /**
  * Start UDP transport.
diff --git a/pjsip/include/pjsip/sip_util.h b/pjsip/include/pjsip/sip_util.h
index f55cd7e9..ea0fcf3f 100644
--- a/pjsip/include/pjsip/sip_util.h
+++ b/pjsip/include/pjsip/sip_util.h
@@ -20,6 +20,7 @@
 #define __PJSIP_SIP_MISC_H__
 
 #include <pjsip/sip_msg.h>
+#include <pjsip/sip_resolve.h>
 
 PJ_BEGIN_DECL
 
@@ -34,6 +35,15 @@ PJ_BEGIN_DECL
  * request outside a dialog, such as OPTIONS, MESSAGE, etc. To create a request
  * inside a dialog, application should use #pjsip_dlg_create_request.
  *
+ * This function adds the following headers in the request:
+ *  - From, To, Call-ID, and CSeq,
+ *  - Contact header, if contact is specified.
+ *  - A blank Via header.
+ *  - Additional request headers (such as Max-Forwards) which are copied
+ *    from endpoint configuration.
+ *
+ * In addition, the function adds a unique tag in the From header.
+ *
  * Once a transmit data is created, the reference counter is initialized to 1.
  *
  * @param endpt	    Endpoint instance.
@@ -62,7 +72,16 @@ PJ_DECL(pj_status_t) pjsip_endpt_create_request( pjsip_endpoint *endpt,
 
 /**
  * Create an independent request message from the specified headers. This
- * function will shallow clone the headers and put them in the request.
+ * function will clone the headers and put them in the request.
+ *
+ * This function adds the following headers in the request:
+ *  - From, To, Call-ID, and CSeq,
+ *  - Contact header, if contact is specified.
+ *  - A blank Via header.
+ *  - Additional request headers (such as Max-Forwards) which are copied
+ *    from endpoint configuration.
+ *
+ * In addition, the function adds a unique tag in the From header.
  *
  * Once a transmit data is created, the reference counter is initialized to 1.
  *
@@ -92,31 +111,6 @@ pjsip_endpt_create_request_from_hdr( pjsip_endpoint *endpt,
 				     pjsip_tx_data **p_tdata);
 
 /**
- * Send outgoing request and initiate UAC transaction for the request.
- * This is an auxiliary function to be used by application to send arbitrary
- * requests outside a dialog. To send a request within a dialog, application
- * should use #pjsip_dlg_send_msg instead.
- *
- * @param endpt	    The endpoint instance.
- * @param tdata	    The transmit data to be sent.
- * @param timeout   Optional timeout for final response to be received, or -1 
- *		    if the transaction should not have a timeout restriction.
- * @param token	    Optional token to be associated with the transaction, and 
- *		    to be passed to the callback.
- * @param cb	    Optional callback to be called when the transaction has
- *		    received a final response. The callback will be called with
- *		    the previously registered token and the event that triggers
- *		    the completion of the transaction.
- *
- * @return	    PJ_SUCCESS, or the appropriate error code.
- */
-PJ_DECL(pj_status_t) pjsip_endpt_send_request( pjsip_endpoint *endpt,
-					       pjsip_tx_data *tdata,
-					       int timeout,
-					       void *token,
-					       void (*cb)(void*,pjsip_event*));
-
-/**
  * Construct a minimal response message for the received request. This function
  * will construct all the Via, Record-Route, Call-ID, From, To, CSeq, and 
  * Call-ID headers from the request.
@@ -125,14 +119,16 @@ PJ_DECL(pj_status_t) pjsip_endpt_send_request( pjsip_endpoint *endpt,
  *
  * @param endpt	    The endpoint.
  * @param rdata	    The request receive data.
- * @param code	    Status code to be put in the response.
+ * @param st_code   Status code to be put in the response.
+ * @param st_text   Optional status text, or NULL to get the default text.
  * @param p_tdata   Pointer to receive the transmit data.
  *
  * @return	    PJ_SUCCESS, or the appropriate error code.
  */
 PJ_DECL(pj_status_t) pjsip_endpt_create_response( pjsip_endpoint *endpt,
 						  const pjsip_rx_data *rdata,
-						  int code,
+						  int st_code,
+						  const pj_str_t *st_text,
 						  pjsip_tx_data **p_tdata);
 
 /**
@@ -143,13 +139,16 @@ PJ_DECL(pj_status_t) pjsip_endpt_create_response( pjsip_endpoint *endpt,
  * this one.
  * 
  * @param endpt	    The endpoint.
- * @param tdata	    On input, this contains the original INVITE request, and on
- *		    output, it contains the ACK message.
- * @param rdata	    The final response message.
+ * @param tdata	    This contains the original INVITE request
+ * @param rdata	    The final response.
+ * @param ack	    The ACK request created.
+ *
+ * @return	    PJ_SUCCESS, or the appropriate error code.
  */
-PJ_DECL(void) pjsip_endpt_create_ack( pjsip_endpoint *endpt,
-				      pjsip_tx_data *tdata,
-				      const pjsip_rx_data *rdata );
+PJ_DECL(pj_status_t) pjsip_endpt_create_ack( pjsip_endpoint *endpt,
+					     const pjsip_tx_data *tdata,
+					     const pjsip_rx_data *rdata,
+					     pjsip_tx_data **ack);
 
 
 /**
@@ -162,25 +161,197 @@ PJ_DECL(void) pjsip_endpt_create_ack( pjsip_endpoint *endpt,
  * @return	    PJ_SUCCESS, or the appropriate error code.
  */
 PJ_DECL(pj_status_t) pjsip_endpt_create_cancel( pjsip_endpoint *endpt,
-						pjsip_tx_data *tdata,
+						const pjsip_tx_data *tdata,
 						pjsip_tx_data **p_tdata);
 
 
 /**
- * Get the address parameters (host, port, flag, TTL, etc) to send the
- * response.
+ * Find which destination to be used to send the request message, based
+ * on the request URI and Route headers in the message. The procedure
+ * used here follows the guidelines on sending the request in RFC 3261
+ * chapter 8.1.2.
+ *
+ * This function may modify the message (request line and Route headers),
+ * if the Route information specifies strict routing and the request
+ * URI in the message is different than the calculated target URI. In that
+ * case, the target URI will be put as the request URI of the request and
+ * current request URI will be put as the last entry of the Route headers.
+ *
+ * @param tdata	    The transmit data containing the request message.
+ * @param dest_info On return, it contains information about destination
+ *		    host to contact, along with the preferable transport
+ *		    type, if any. Caller will then normally proceed with
+ *		    resolving this host with server resolution procedure
+ *		    described in RFC 3263.
+ *
+ * @return	    PJ_SUCCESS, or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pjsip_get_request_addr( pjsip_tx_data *tdata,
+					     pjsip_host_info *dest_info );
+
+
+/**
+ * This structure holds the state of outgoing stateless request.
+ */
+typedef struct pjsip_send_state
+{
+    /** Application token, which was specified when the function
+     *  #pjsip_endpt_send_request_stateless() is called.
+     */
+    void *token;
+
+    /** Endpoint instance. 
+     */
+    pjsip_endpoint *endpt;
+
+    /** Transmit data buffer being sent. 
+     */
+    pjsip_tx_data *tdata;
+
+    /** Server addresses resolved. 
+     */
+    pjsip_server_addresses   addr;
+
+    /** Current server address being tried. 
+     */
+    unsigned cur_addr;
+
+    /** Current transport being used. 
+     */
+    pjsip_transport *cur_transport;
+
+    /** The application callback which was specified when the function
+     *  #pjsip_endpt_send_request_stateless() was called.
+     */
+    void (*app_cb)(struct pjsip_send_state*,
+		   pj_ssize_t sent,
+		   pj_bool_t *cont);
+} pjsip_send_state;
+
+/**
+ * Send outgoing request statelessly The function will take care of which 
+ * destination and transport to use based on the information in the message,
+ * taking care of URI in the request line and Route header.
+ *
+ * This function is different than #pjsip_transport_send() in that this 
+ * function adds/modify the Via header as necessary.
+ *
+ * @param endpt	    The endpoint instance.
+ * @param tdata	    The transmit data to be sent.
+ *
+ * @return	    PJ_SUCCESS, or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) 
+pjsip_endpt_send_request_stateless( pjsip_endpoint *endpt,
+				    pjsip_tx_data *tdata,
+				    void *token,
+				    void (*cb)(pjsip_send_state*,
+					       pj_ssize_t sent,
+					       pj_bool_t *cont));
+
+/**
+ * This structure describes destination information to send response.
+ * It is initialized by calling #pjsip_get_response_addr().
+ *
+ * If the response message should be sent using transport from which
+ * the request was received, then transport, addr, and addr_len fields
+ * are initialized.
+ *
+ * The dst_host field is also initialized. It should be used when server
+ * fails to send the response using the transport from which the request
+ * was received, or when the transport is NULL, which means server
+ * must send the response to this address (this situation occurs when
+ * maddr parameter is set, or when rport param is not set in the request).
+ */
+typedef struct pjsip_response_addr
+{
+    pjsip_transport *transport;	/**< Immediate transport to be used. */
+    pj_sockaddr	     addr;	/**< Immediate address to send to.   */
+    int		     addr_len;	/**< Address length.		     */
+    pjsip_host_info  dst_host;	/**< Destination host to contact.    */
+} pjsip_response_addr;
+
+/**
+ * Determine which address (and transport) to use to send response message
+ * based on the received request. This function follows the specification
+ * in section 18.2.2 of RFC 3261 and RFC 3581 for calculating the destination
+ * address and transport.
+ *
+ * The information about destination to send the response will be returned
+ * in res_addr argument. Please see #pjsip_response_addr for more info.
  *
  * @param pool	    The pool.
- * @param tr	    The transport where the request was received.
- * @param via	    The top-most Via header of the request.
- * @param addr	    The send address concluded from the calculation.
+ * @param rdata	    The incoming request received by the server.
+ * @param res_addr  On return, it will be initialized with information about
+ *		    destination address and transport to send the response.
  *
  * @return	    zero (PJ_OK) if successfull.
  */
 PJ_DECL(pj_status_t) pjsip_get_response_addr(pj_pool_t *pool,
-					     const pjsip_transport *tr,
-					     const pjsip_via_hdr *via,
-					     pjsip_host_info *addr);
+					     pjsip_rx_data *rdata,
+					     pjsip_response_addr *res_addr);
+
+/**
+ * Send response in tdata statelessly. The function will take care of which 
+ * response destination and transport to use based on the information in the 
+ * Via header (such as the presence of rport, symmetric transport, etc.).
+ *
+ * This function will create a new ephemeral transport if no existing 
+ * transports can be used to send the message to the destination. The ephemeral
+ * transport will be destroyed after some period if it is not used to send any 
+ * more messages.
+ *
+ * The behavior of this function complies with section 18.2.2 of RFC 3261
+ * and RFC 3581.
+ *
+ * @param endpt	    The endpoint instance.
+ * @param res_addr  The information about the address and transport to send
+ *		    the response to. Application can get this information
+ *		    by calling #pjsip_get_response_addr().
+ * @param tdata	    The response message to be sent.
+ * @param token	    Token to be passed back when the callback is called.
+ * @param cb	    Optional callback to notify the transmission status
+ *		    to application, and to inform whether next address or
+ *		    transport will be tried.
+ * 
+ * @return	    PJ_SUCCESS if response has been successfully created and
+ *		    sent to transport layer, or a non-zero error code. 
+ *		    However, even when it returns PJ_SUCCESS, there is no 
+ *		    guarantee that the response has been successfully sent.
+ */
+PJ_DECL(pj_status_t) pjsip_endpt_send_response( pjsip_endpoint *endpt,
+					        pjsip_response_addr *res_addr,
+					        pjsip_tx_data *tdata,
+						void *token,
+						void (*cb)(pjsip_send_state*,
+							   pj_ssize_t sent,
+							   pj_bool_t *cont));
+
+/**
+ * Send outgoing request and initiate UAC transaction for the request.
+ * This is an auxiliary function to be used by application to send arbitrary
+ * requests outside a dialog. To send a request within a dialog, application
+ * should use #pjsip_dlg_send_msg instead.
+ *
+ * @param endpt	    The endpoint instance.
+ * @param tdata	    The transmit data to be sent.
+ * @param timeout   Optional timeout for final response to be received, or -1 
+ *		    if the transaction should not have a timeout restriction.
+ * @param token	    Optional token to be associated with the transaction, and 
+ *		    to be passed to the callback.
+ * @param cb	    Optional callback to be called when the transaction has
+ *		    received a final response. The callback will be called with
+ *		    the previously registered token and the event that triggers
+ *		    the completion of the transaction.
+ *
+ * @return	    PJ_SUCCESS, or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pjsip_endpt_send_request( pjsip_endpoint *endpt,
+					       pjsip_tx_data *tdata,
+					       int timeout,
+					       void *token,
+					       void (*cb)(void*,pjsip_event*));
+
 
 /**
  * @}
diff --git a/pjsip/include/pjsip_core.h b/pjsip/include/pjsip_core.h
index 8ae286a5..9f3c7e9b 100644
--- a/pjsip/include/pjsip_core.h
+++ b/pjsip/include/pjsip_core.h
@@ -31,6 +31,7 @@
 #include <pjsip/sip_tel_uri.h>
 #include <pjsip/sip_transaction.h>
 #include <pjsip/sip_transport.h>
+#include <pjsip/sip_transport_udp.h>
 #include <pjsip/sip_uri.h>
 #include <pjsip/sip_util.h>