[Shtoom] bug report: media port off by 2 error

[zooko at zooko.com]

http://zooko.com/cgi-bin/darcs.cgi/shtoom/zookobranch/Shtoom/shtoom/doc/BUGS.txt?c=annotate&p=20041025121431-92b7f-7d10512cb7ac9756fccad4b4f0c81c71e0b63235.gz

name: media port off by 2 error
to reproduce: run Shtoom behind NAT, let it use STUN to discover externally-visible port numbers
details: the port numbers returned by STUN are the port numbers Shtoom listens on, but the port numbers it puts in the "media" line in SDP are +2
more details: I discovered this while trying to demo a Shtoom-derived product.  I worked-around it by telling the other UA to subtract 2 from the RTP port in the SDP.  This worked, enabling the other UA to send media packets to the behind-NAT-Shtoom.