SYNOPSIS

my $ctx = Net::SIP::Endpoint::Context->new( to => .., from => .. );
my $request = $ctx->new_request(..);

DESCRIPTION

This package manages the call context (from,to,call-id, recorded routes..) for a call to an Net::SIP::Endpoint. It maintains the state of the current call (local and remote cseq, current state within INVITE transaction) and handles requests and responses according to this state.

CONSTRUCTOR

new ( ARGS )

ARGS is either a hash reference or a hash. It contains the following mandatory keys:

from

Initiator of call. This is the local address for outgoing calls and the peers address for incoming calls.

to

Target of call.

And the following optional keys:

contact

Contact info for context.

incoming

Flag, if the context resulted from an incoming call.

auth

Authorization info, used if outgoing requests need authorization. See method authorize in Net::SIP::Request for information on the format.

route

\@List of predefined routes (which will be used to create Route SIP header in requests).

via

\@List of predefined Via values used in locally generated responses. This is usually set if the context was created by an incoming request from the Via header in the request.

callid

Value of Call-Id header. If not given it will be generated. It's usually given for incoming calls, but not for outgoing calls.

cseq

Initial local sequence number for the CSeq SIP header. Defaults to 0, e.g. the first request will get the sequence number 1.

METHODS

callid

Returns callid of current call.

peer

Returns peer of call. For incoming calls this is the sender, for outgoing calls the recipient of the call.

new_request ( METHOD, [ BODY, %ARGS ] )

Creates a new requests for method METHOD with body BODY and additional SIP headers defined by %ARGS. The headers for "to", "from", "contact", "route" will be created from the call context info in $self.

One special ARGS can be resp40x which should point to a 401/407 SIP response containing the offer from the server for authorization. This way authorization can be fully controlled, e.g. first trying w/o authorization and then retrying with authorization credentials and the 40x response.

METHOD might be already a Net::SIP::Request object in which case it will be used unmodified. BODY might be a string or object (see constructor of Net::SIP::Request).

It will add the request to the list of active transactions within the context $self, e.g. will be prepared to get responses for it. The callback for the transaction is copied from the default callback for the context, so that it stays the same, even if the default callback changes.

It returns the created request object.

find_outstanding_requests ( %FILTER )

Returns list of outstanding requests (e.g INVITE w/o reply) for this context. Returns a list of outstanding request (Net::SIP::Request objects) with the most recent requests first.

FILTER might be used to restrict the search. With key request a Net::SIP::Request object is expected and it will restrict the search to this object (e.g. it will return the object if it is outstanding). With key method a method can be specified and only requests with this method will be returned.

set_callback ( CALLBACK )

Sets callback for context, which will be used if the upper layer need to be notified, e.g on incoming requests or an permanent delivery errors. CALLBACK is a callback usable by invoke_callback in Net::SIP::Util and will be invoked with the following arguments (some arguments make only sense for incoming packets).

CTX

The call context, e.g. $self.

ENDPOINT

The Net::SIP::Endpoint object managing CTX.

ERROR

The errno of the error occured ( undef or 0 if no error ). These are the same numbers defined in Errno, but they are usually not set by a system call, but by the dispatcher (like ETIMEDOUT if delivery failed permanently after none of the retransmits succeeded or EHOSTUNREACH if it cannot resolve the SIP URI).

CODE

This is the response CODE from an incoming response packet. Undef if the incoming packet was no response.

PACKET

This is the packet which caused the callback. Only for incoming packets.

LEG

Net::SIP::Leg where the packet came in.

FROM

"ip:port" of sender of incoming packet.

request_delivery_done ( ENDPOINT, TID, ERROR )

Callback setup at delivery of the packet and called with ERROR FALSE if the packet was delivered successfully over a reliable transport or with ERROR an errno if the packet could not be delivered (or no reply came in for packet, so one can assume that the recipient did not get it).

For details on ERROR see set_callback.

TID is the transaction ID, see method tid in Net::SIP::Packet. ENDPOINT is the endpoint managing the context $self.

handle_response ( RESPONSE,LEG,FROM,ENDPOINT )

Called from the endpoints receive_response method it handles responses to requests originated from the context $self.

RESPONSE is the response packet, LEG the leg where the packet came in and FROM the "ip:port" of the sender. ENDPOINT is the endpoint managing the context $self.

First it checks if the response matches an active transaction (which begun its life in new_request) and if not it drops the response.

Then it checks if the response came in to the right leg, e.g. if the Via header of the packet matches the Via header the leg creates. If not the packet will be dropped.

Then it checks if the method in the CSeq header of the response matches the expected method in the transaction (for INVITEs this could be either INVITE or ACK, depending on the state of the transaction). If it not matches the packet will be dropped. (All of these packet drops could be observed if you enable debugging, see Net::SIP::Debug.

If the response is for a BYE or CANCEL request the call will be closed.

If the response is the unsuccessful final response for an INVITE an ACK will be send, if it's preliminary response it will invoke the callback for the transaction.

If the response is a successful final response for an INVITE it will save the routes from the Record-Route header for future requests and create an ACK request. The transaction callback will be invoked and gets as an additional argument the created ACK request, which then can be modified by the callback. The callback should not send the ACK request by itself, it should just modify the given request and sending will be done after the callback returned.

If the response is a successful final response to a request other then INVITE it will invoke callback which should fully handle the response.

If the response code is 401 (Authorization required) or 407 (Proxy Authorization required) and if the context has authorization info (key auth in the constructor)) it will try to authorize the request based on the realms given in the response and if it can find authorization info for at least parts of the required realms it will redeliver the request. Otherwise it will invoke the callback with an error of EPERM.

If the response code is 300 (multiple choice) or 301 (moved permanently) it will invoke the callback because it cannot resolve the issue automatically. But if it's 302 (moved temporally) it will rewrite the request based on the Contact header in the response and redeliver it automatically.

If the response is 305 (use proxy) it will take the information from Contact as the upstream proxy and insert it into the routes, so that it will use it as the next hop. Then it rewrites the request for the new routes and redelivers it.

For all other responses the callback will be invoked, e.g the issue has to be resolved by the users application.

handle_request ( REQUEST,LEG,FROM,ENDPOINT )

Called from the endpoints receive_request method it handles incoming requests for call context $self.

REQUEST is the request packet, LEG the leg where the packet came in and FROM the "ip:port" of the sender. ENDPOINT is the endpoint managing the context $self.

First it checks if the sequence number of the incoming request (CSeq header) is not lower then the sequence number of the last request received. Otherwise it will drop the request.

The it checks if the sequence number is the same as for the last request. If it is higher it must be a new request, otherwise it is a retransmit or an ACK or CANCEL to an INVITE request. If it's a retransmit it will be dropped.

If the incoming request is an INVITE it will automatically deliver a response "100 Trying" and then invoke the callback, so that the application might issue "180 Ringing" responses and finally a final response, like "200 Ok".

If the incoming request is CANCEL or BYE it will issue a response "200 Closing" and close the context.

All other requests must be handled by the application, e.g. the callback will be invoked.