TODOs, in random order:
=======================

- REGISTER: updatinf the registration table
  currently done upon passing an REGISTER request through, independent of
  the outcome of the registration, the registration entry will be put into
  the table.
  IF a client now tries to register a non-existent number, a fake entry ends
  up in the table and may mess things up.
  Solution: The lifetime of a REGISTER should be set at receiving the successful
  REGISTER Response - before the successful response (at least initially) the
  entry should be regarded as invalid.

  1)
  REGISTER request only gives 5 seconds registration time
  unsuccessful REGISTER response does nothing (clock ticking)
  successful REGISTER response gives full registration time
  -> this reduces the window of opportunity 
  
  May want to do further: introduce negative grace time that makes REGISTER
  dialog mapping work, but is ignored for all other methods
  -> marking records as inactive upon -10 seconds (#define REGISTRATION_GRACE)
  -> for REGISTER dialogs, have match if active && urlmatch
  -> for all other dialogs, have match if active && expiration>0 && urlmatch


- check via loop and private IP addresses
  can comment be used to store a unique ID in there?

- multiple inbound interfaces - do I need to be aware of inbound at all?

- Documentation (yeah, yeah...)

- general security issues
- security tests for received SIP messages (function securitycheck)

- automagically create a proper config file during install

- get_ip_by_host: reduce DNS timeouts (seems to be a more complex problem...)

- via loop detection: send 482 error code

- feature: don't bind to 0.0.0.0 address, but only to inbound/outbound IF's
  (defined by IFNAME)

RFC3261 non-compliance:
- Record-Route header handling

- OpenBSD: Warning for redefinition of MACROS

- remove URLMAP_SIZE and RTPPROXY_SIZE constants, make them configurable 
  at runtime.