Provided by: libnet-sip-perl_0.836-1_all 
NAME
Net::SIP::Endpoint::Context - Call context for endpoint
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 occurred ( 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 (Unauthorized) or 407 (Proxy Authentication 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 Choices) or 301 (moved permanently) it will
invoke the callback because it cannot resolve the issue automatically. But if it's
302 (Moved Temporarily) 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.