Net::SIP::Leg(3) Wrapper around Socket for sending and receiving SIP packets


my $leg = Net::SIP::Leg->new( addr => '' );
$leg->deliver( $packet, '' );


A Leg wraps the socket which is used to send and receive packets. It provides ways to strip Via header from incoming packets, to add Via header to outgoing packets and to add Record-Route header while forwarding.

It's usually not used directly, but from Net::SIP::Dispatcher.


new ( %ARGS )
The constructor creates a new object based on the hash %ARGS. The following keys are used from %ARGS:
The socket as IO::Socket::INET object. "addr", "port" and "proto" will be determined from this object and not from %ARGS.
The local address of the socket. If this is given but no port it will extract port from addr, if it's in the format "host:port".
The port of the socket. Defaults to 5060.
The connection protocol, e.g. 'tcp' or 'udp'. Defaults to 'udp'.
Optional contact information which will be added as Record-route header to outgoing requests and used within Contact header for 200 Responses to INVITE. If not given it will be created based on "addr", "port" and "proto".

If no socket is given with "sock" it will be created based on "addr", "port" and "proto". If this fails the constructur will "die()".

The constructor will creeate a uniq branch tag for this leg.


forward_incoming ( PACKET )
Modifies the Net::SIP::Packet PACKET in-place for forwarding, e.g strips top Via header in responses, adds received parameter to top Via header in requests, handles the difference between forwarding of requests to strict or loose routes and inserts Record-Route header in requests.
forward_outgoing ( PACKET, LEG_IN )
Similar to forward_incoming, but will be called on the outgoing leg. LEG_IN is the Net::SIP::Leg, where the packet came in (and where forward_incoming was called). Will add Record-Route header and remove itself from Route.
deliver ( PACKET, ADDR, [ CALLBACK ] )
Delivers Net::SIP::Packet PACKET through the leg $self to ADDR, which is "ip:port". Usually this method will be call from within Net::SIP::Dispatcher.

If the packet was received by the other end (which is only possible to say if a reliable protocol, e.g. 'tcp' was used) it will call CALLBACK if provided. See invoke_callback in Net::SIP::Util for the format of callbacks. If the packet could not be delivered CALLBACK will be invoked with the appropriate errno ($!).

While delivering requests it adds a Via header.

Reads a packet from the socket and returns the Net::SIP::Packet PACKET and the senders ADDR as "ip:port". If reading failed will return "()".
check_via ( PACKET )
Returns TRUE if the top Via header in the Net::SIP::Packet PACKET contains the branch-tag from $self, otherwise FALSE. Used to check if the response came in through the same leg the response was send.
add_via ( PACKET )
Adds itself to PACKET as Via header.
can_deliver_to ( ADDR|%SPEC )
Returns TRUE if the leg can deliver address specified by ADDR or %SPEC. ADDR is a hostname which can be prefixed by the protocol ( e.g. "udp:host" ) and postfixed by the port ( "host:port", "tcp:host:port",... ).

If the caller has 'proto','addr' and 'port' already as separate items it can call the method with %SPEC instead.

Right now it has now way to check if the leg can deliver to a specific host because it has no access to the routing information of the underlying OS, so that only proto will be checked.

Returns socket of leg. In some special environments (like tests) there might be legs, which don't have a socket associated. In this case you need to call receive from Net::SIP::Dispatcher yourself, because it cannot be called automatically once it receives data on the socket.
Returns string containing information about the leg. Used for debugging.