Net::SIP::NATHelper::Base - rewrite SDP and transport RTP for NAT
This module helps with doing NAT. It is implicitly used in do_nat from Net::SIP::StatelessProxy.
It cares about the rewriting the SDP bodies, forwarding RTP data for active sessions and expiring sessions.
Creates a new object.
This is called to allocate new local sockets for MEDIA. MEDIA is a \@list of specifications like you get from get_media in Net::SIP::SDP. ADDR is the local address, where the sockets should be allocated.
CALLID and CSEQ are used to identify the SIP transaction, for which the NAT will be done, while IDSIDE is either IDFROM or IDTO (see below) depending on the side, where the packet came in.
The method returns a \@list of new media in the format needed by replace_media_listen in Net::SIP::SDP.
If the allocation of sockets failed (because of resource constraints) it will return undef. This will usually cause the caller do simply not forward the packet and wait for the reetransmit (at least for UDP).
Activates a session in the transaction defined by CALLID,CSEQ. This will cause all sessions for other transactions for the same call (identified by CALLID) to shut down.
IDFROM and IDTO represent the sides of the session, e.g. for the activation to succeed there had to be an allocate_sockets call for each of these sides.
The method returns TRUE only if the activation succeeded. It is usually called whenever a SDP body is given and on ACK requests.
This will cause the close of the session described by the arguments (which have the same meaning like in activate_session). Usually called for BYE or CANCEL requests.
It will return TRUE only if the session existed. Stateless proxies should ignore the return code and forward the packet nonetheless, because it's probably a retransmit.
This causes the sessions and sockets to expire. Expiration will be done after 3 minutes of inactivity (this value comes implicitly from the SIP specifications about retransmits...).
Returns TRUE if changes were made.
This will return a list (not a reference) of [fd,callback] pairs, where fd is the file descriptor of the socket and callback is a callback for invoke_callback in Net::SIP::Util.
[fd,callback]
Each of these callbacks should be invoked once the file descriptor gets readable and the callback will then forward the received packet to the other side of the session.
This method is used for debugging only. It will return a string with information about all calls within this nathelper and all sessions and allocated sockets within the calls.
Returns the number of calls within the nathelper. This vaalue has not much association with the result of callbacks because there might be inactive sockets (not yet or no longer in active session) which don't affect the result of callbacks.
This value can be used to determine if expire needs to be called at all.
To install Net::SIP, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Net::SIP
CPAN shell
perl -MCPAN -e shell install Net::SIP
For more information on module installation, please visit the detailed CPAN module installation guide.