VoIPER : VoIP Exploit Research toolkit

On Ubuntu an exception occurs after sending a few thousand INVITE requests
against OpenSER with no CANCELs. This appears to be because the sockets
used to send the INVITEs are never closed. This probably happens because
OpenSER keeps trying to resend responses to the initial invite but we are
not providing anything to handle these when do_cancel is false. As a result
the transaction manager constantly updates the 'timeout' for the
transaction and the socket is never cleaned up.

A quick fix is to set the transaction timeout from the fuzzer to 0 to begin
with.