Yate handles SIP requests differently, depending on the request method.
You can also generate SIP requests from Yate (from other modules/custom scripts) and they will be sent to a specific party.
What is a SIP Request Method?
A SIP request method defines the nature and the purpose of the SIP request.
This the list of SIP request methods:
- INVITE - Requests a session.
- ACK - Final response to the INVITE
- OPTIONS - Ask for server capabilities
- BYE - Terminates a session
- PRACK - Similar to ACK, but a provisional confirmation.
- CANCEL - Cancel any pending requests.
- REGISTER - Registers the client with the server according to the address in the To header field.
- INFO - Sends information in the middle of a session that doesn't modify the session's state.
- SUBSCRIBE -Subscribes the device for an event notification.
- NOTIFY - Notifies all subscribers of an event.
- PUBLISH - Publishes an event to a server.
- REFER - Asks the client to issue a SIP request, typically a call transfer.
- MESSAGE - Sends an instant message using SIP.
- UPDATE - Modifies a session's state without altering the dialog state.
SIP methods in Yate
In Yate some SIP requests are handled internally while others are handled generically.
When a SIP request arrives in Yate it will – depending on the request method – either be handled in the ysipchan module (internally handled), or an internal yate message named sip.methodname will be sent (generically handled). The handling of generically handled messages is done in other modules/external scripts.
Internally handled methods
Internally handled request methods are requests handled directly by ysipchan module. Yate messages like sip.methodname won't be generated for them.
The methods are handled internally by Yate:
- methods that are always handled when ysipchan module is enabled
- methods that are handled in the default configuration and that can be enabled/disabled from [general] section
- INFO - controlled by info setting. If request is received during a dialog initiated by an INVITE and it's used for application/dtmf-relay or application/dtmf then it's handled internally. Outside a dialog it's handled generically.
- OPTIONS - controlled by options setting.
- methods that are handled in the default configuration when yate is started in server mode, and are disabled when yate is started in client mode. They can be enabled/disabled from [general] section
- REFER - controlled by transfer setting
- REGISTER - controlled by register setting. If register=enabled then [registrar] section defines how Yate will work as a SIP REGISTRAR. Before starting yate as SIP registrar set users in regfile.conf or in register.conf.
- methods that are disabled in the default configuration but can be enabled/disabled from [general] section
- PRACK - controlled by prack setting
Generically handled methods
Generically handled SIP methods are methods that are not handled in the ysipchan module.
In order to handle other methods besides those listed above you must enable them in the [methods] section. Some have separate yate modules that handle them while others don't, so you need to define the handling of the message in a custom way when enabling them.
When Yate receives a request for one of the enabled methods, it will generate a generic SIP message. This message will be handled from a module or from an external script.
Requests genenerated from Yate
In some cases you might need to initiate SIP requests from a module in Yate and send them to a specific party.
In this case you should send xsip.generate message from the module/script where the logic is implemented. The ysipchan module handles this message and sends the SIP request to the specified party.
This happens when Yate sends NOTIFY requests to the users that subscribed to a certain event. Or you can follow the setup for sending chat messages between SIP users that uses both SIP generic messages and xsip.generate.
SIP generic message
SIP generic messages are messages generated by the ysipchan module on receiving the specified requests in [methods] section.
The syntax is: sip.methodname, where methodname is the name of the received SIP request (e.g. sip.subscribe).
- The dialog tag of the received request.
- The request URI of the received SIP method.
- The content type header.
- Where headername is the name of the header received with the request. This parameter is repeated for each header in the request (e.g. sip_from, sip_to, etc).
A module processing this message should set the 'code' parameter of the message to a SIP response code.
The processing module may also set message's parameters named osip_headername to be returned in the SIP response (e.g. osip_Expires).
Yate receives a SIP request for MESSAGE method as below:
<sip:INFO> 'udp:0.0.0.0:5062' received 381 bytes SIP message from 192.168.168.156:5060 [0x890f858] ------ MESSAGE sip:firstname.lastname@example.org SIP/2.0 Via: SIP/2.0/UDP 192.168.168.156;rport;branch=z9hG4bKmibzipmn Max-Forwards: 70 To: <sip:email@example.com> From: "DanielaGrigore" <sip:firstname.lastname@example.org>;tag=hhzbn Call-ID: email@example.com CSeq: 427 MESSAGE Content-Type: text/plain;charset=utf-8 User-Agent: Twinkle/1.4.1 Content-Length: 12 hello Monica ------
And emits a sip.message:
Sniffed 'sip.message' time=1352472395.780609 thread=0x890d348 'YSIP EndPoint' data=(nil) retval='(null)' param['username'] = '123' param['realm'] = 'Yate' param['ip_transport'] = 'UDP' param['newcall'] = 'false' param['domain'] = '192.168.168.156' param['device'] = 'Twinkle/1.4.1' param['connection_id'] = 'general' param['connection_reliable'] = 'false' param['username'] = '123' param['called'] = '234' param['caller'] = '123' param['callername'] = 'DanielaGrigore' param['antiloop'] = '19' param['address'] = '192.168.168.156:5060' param['ip_host'] = '192.168.168.156' param['ip_port'] = '5060' param['ip_transport'] = 'UDP' param['sip_uri'] = 'sip:firstname.lastname@example.org' param['sip_callid'] = 'email@example.com' param['xsip_dlgtag'] = '2078093122' param['sip_to'] = '<sip:firstname.lastname@example.org>' param['sip_from'] = '"DanielaGrigore" <sip:email@example.com>;tag=hhzbn' param['sip_content-type'] = 'text/plain;charset=utf-8' param['sip_user-agent'] = 'Twinkle/1.4.1' param['xsip_type'] = 'text/plain' param['xsip_body'] = 'hello Monica'
Follow the example below for a full configuration on how the enable and handle the MESSAGE method.