Source Specific IP address not honored in IGMPv3 requests on OS X (Lion)
Apple Mac OS X Lion (10.7) introduced the support of IGMPv3 in the kernel and API. VLC has supported IGMPv3 for many years on other platforms that can take advantage of it (Windows, Linux, etc) but on OS X it doesn't appear to work properly.
If a user running VLC 2.0.1 (tested with OS X 64-bit client) attempts to join a source such as rtp://firstname.lastname@example.org:1234 (either via a SDP message in a SAP announcement or from the application interface under File, Open Network), the IGMPv3 request will actually request membership for the group (220.127.116.11) but with source "any" instead of the source specific include for 192.168.1.11.
For sanity check, the same request works fine under Windows 7 with VLC 2.0.1 client
Attached are 2 pcaps, the correct request under Windows 7, and the incorrect one under OS X 10.7.2
I'm unable to confirm/deny if this issue is VLC specific or VLC/OS X API linked.
RFC 3376 (Internet Group Management Protocol, Version 3) include/add new source and exclude/block old sources requirement are in section 4.2.12