[Serdev] maddr parameter support for REGISTER

[Maxim Sobolev]

Folks,

One of our clients bumped into the problem with Nortel's softphone. The 
phone uses maddr URI parameter to indicate its own IP address in the 
Contact header of the REGISTER request. That is, it puts SIP server's IP 
into host portion of URI and its own IP address into maddr parametr. 
Since SER has no special handling for maddr, after successful lookup() 
it sends request to itself, instead of sending it to the UA.

According to RFC, if URI contains maddr parameter it should be used 
instead of host portion of the URI when forwarding message to that URI. 
Therefore, it seems that phone behaves correctly.

In my opinion there are two ways to resolve this problem:

1. Extend save() function to replace host portion of the URI with the 
maddr value if present and remove maddr parameter before saving contact 
into the location database.

2. Extend forwarding logic to respect maddr parameter when deciding 
where to send the message.

What do you think?

-Maxim