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<h2><a href="https://wiki.asterisk.org/wiki/display/AST/res_sip_session+design">res_sip_session design</a></h2>
<h4>Page <b>edited</b> by <a href="https://wiki.asterisk.org/wiki/display/~mmichelson">Mark Michelson</a>
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<h4>Changes (1)</h4>
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<tr><td class="diff-snipped" >...<br></td></tr>
<tr><td class="diff-unchanged" >h1. Startup procedure <br> <br></td></tr>
<tr><td class="diff-changed-lines" >When {{res_sip_session}} starts up, it registers itself with {{res_sip}} as a service. <span class="diff-added-words"style="background-color: #dfd;">This will cause {{res_sip}} to call into {{res_sip_session}} when new SIP messages come in. {{res_sip_session}} will handle those associated with sessions (i.e. INVITEs, in-dialog REFER and INFO, UPDATEs, and PRACKs).</span> <br></td></tr>
<tr><td class="diff-unchanged" > <br>h1. Public methods <br></td></tr>
<tr><td class="diff-snipped" >...<br></td></tr>
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</div> <h4>Full Content</h4>
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<h1><a name="res_sip_sessiondesign-Overview"></a>Overview</h1>
<p><tt>res_sip_session</tt> represents the "core" of SIP session operations. In the context of SIP, a "session" refers to a media session, such as a phone call. The SIP channel driver will be a consumer of the services provided by <tt>res_sip_session</tt>.</p>
<h1><a name="res_sip_sessiondesign-Startupprocedure"></a>Startup procedure</h1>
<p>When <tt>res_sip_session</tt> starts up, it registers itself with <tt>res_sip</tt> as a service. This will cause <tt>res_sip</tt> to call into <tt>res_sip_session</tt> when new SIP messages come in. <tt>res_sip_session</tt> will handle those associated with sessions (i.e. INVITEs, in-dialog REFER and INFO, UPDATEs, and PRACKs).</p>
<h1><a name="res_sip_sessiondesign-Publicmethods"></a>Public methods</h1>
<h2><a name="res_sip_sessiondesign-Structures"></a>Structures</h2>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="theme: Confluence; brush: c; gutter: false">/*!
* \brief A structure describing a SIP session
*/
struct ast_sip_session {
/* The endpoint with which Asterisk is communicating */
struct ast_sip_endpoint *endpoint;
/* The PJSIP details of the session, which includes the dialog */
struct pjsip_inv_session *inv_session;
/* The Asterisk channel associated with the session */
struct ast_channel *channel;
};
/*!
* \brief An extension to SIP message processing
*
* These can be registered by any module in order to add
* processing to incoming and outgoing SIP requests and responses
*/
struct ast_sip_session_extension {
/*! Method on which to call the callbacks. If NULL, call on all methods */
const char *method;
/*! Called on incoming SIP request
* This method can indicate a failure in processing in its return. If there
* is a failure, it is required that this method sends a response to the request.
*/
int (*incoming_request)(struct ast_sip_session *session, struct pjsip_rx_data *rdata);
/*! Called on an incoming SIP response */
void (*incoming_response)(struct ast_sip_session *session, struct pjsip_rx_data *rdata);
/*! Called on an outgoing SIP request */
void (*outgoing_request)(struct ast_sip_session *session, struct pjsip_tx_data *tdata);
/*! Called on an outgoing SIP response */
void (*outgoing_response)(struct ast_sip_session *session, struct pjsip_tx_data *tdata);
};
/*!
* \brief A handler for SDP in SIP INVITEs
*
* An SDP handler is registered by a module that is interested in being the
* responsible party for all aspects SDP.
*/
struct ast_sip_session_sdp_handler {
/*!
* \brief Set session details based on an incoming SDP
*/
int (*handle_incoming_sdp)(struct ast_sip_session *session, struct pjsip_rx_data *rdata);
/*!
* \brief Create an SDP and add it to the outgoing request or response
*/
void (*add_outgoing_sdp)(struct ast_sip_session *session, struct pjsip_tx_data *tdata);
};</pre>
</div></div>
<h2><a name="res_sip_sessiondesign-Extensibility"></a>Extensibility</h2>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="theme: Confluence; brush: c; gutter: false">/*!
* \brief Register an SDP handler
*
* An SDP handler is responsible for parsing incoming SDPs and ensuring that
* Asterisk can cope with the contents. Similarly, the SDP handler will be
* responsible for constructing outgoing SDPs.
*
* \param handler The SDP handler to register
* \retval 0 Success
* \retval -1 Failure
*/
int ast_sip_session_register_sdp_handler(const struct ast_sip_session_sdp_handler *handler);
/*!
* \brief Unregister an SDP handler
*
* \param handler The SDP handler to unregister
*/
void ast_sip_session_unregister_sdp_handler(const struct ast_sip_session_sdp_handler *handler);
/*!
* \brief Register an extension to SIP session processing
*
* This allows for someone to insert themselves in the processing of SIP
* requests and responses. This, for example could allow for a module to
* set channel data based on headers in an incoming message. Similarly,
* a module could reject an incoming request if desired.
*
* \param extension The extension to register
* \retval 0 Success
* \retval -1 Failure
*/
int ast_sip_session_register_extension(struct ast_sip_session_extension *extension);
/*!
* \brief Unregister a an extension to SIP session processing
*
* \param extension The extension to unregister
*/
void ast_sip_session_unregister_extension(struct ast_sip_session_extension *extension);</pre>
</div></div>
<h2><a name="res_sip_sessiondesign-CommonSIPmethods"></a>Common SIP methods</h2>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="theme: Confluence; brush: c; gutter: false">/*!
* \brief Retrieve identifying information from an incoming request
*
* This will retrieve identifying information and place it in the
* id parameter. The caller of the function can then apply this to
* caller ID, connected line, or whatever else may be proper.
*
* \param rdata The incoming request or response
* \param[out] id The collected identity information
* \retval 0 Successfully found identifying information
* \retval -1 Identifying information could not be found
*/
int ast_sip_session_get_identity(struct ast_party_id *id);
/*!
* \brief Send a reinvite on a session
*
* This method will inspect the session in order to construct an appropriate
* reinvite. As with any outgoing request in res_sip_session, this will
* call into registered extensions in case they wish to add anything.
*
* \param session The session on which the reinvite will be sent
* \retval 0 Successfully sent reinvite
* \retval -1 Failure to send reinvite
*/
int ast_sip_session_send_reinvite(struct ast_sip_session *session);
/*!
* \brief Send a SIP response
*
* This will send a SIP response to the request specified in rdata. This will
* call into any registered extensions' outgoing_response callback.
*
* \param session The session to which the current transaction belongs
* \param response_code The response code to send for this response
* \param rdata The response to which the response is being sent
*/
int ast_sip_session_send_response(struct ast_sip_session *session, int response_code, struct pjsip_rx_data *rdata);</pre>
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