UDPSClient::ConnectMulticast was calling the single-arg BasicUDPSocket::Join,
which forwards NULL as the local interface and lets the kernel bind to
INADDR_ANY. On a multi-homed host (or when the server sends on loopback via
Interface = "127.0.0.1") the client joins the wrong interface and silently
receives nothing.
Fix: read the optional Interface key inside the useMulticast block in
UDPSClient::Initialise; in ConnectMulticast call the two-arg
Join(group, interface) when Interface is set, and fall back to the one-arg
call otherwise to preserve the existing INADDR_ANY behaviour for configs that
omit it.
Forward the new optional Interface key through UDPStreamerClient (read from
DataSource config, written into the UDPSClient ConfigurationDatabase only
when non-empty). Extend the "Joined multicast group" log to report the
interface name or "default".
Regression test TestExecute_MulticastReceivesDataOnInterface: mock TCP
control listener + multicast UDP DATA socket with IP_MULTICAST_IF set to
127.0.0.1, verifying a uint32 value of 424242 reaches DataSource signal
memory. Confirmed FAILED without the Join fix and PASSED with it.
Suite: 133/133 (was 132/132 before this commit).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Commit 3e0a481 made Interface mandatory for multicast in both
UDPStreamer::Initialise and UDPSServer::Initialise and updated
Docs/UDPStreamer.md, but left the GTest configs untouched. All four
multicast tests have failed since.
Add Interface to the five multicast configs. The field is parsed with
inet_addr(), so it takes a dotted-quad, not an interface name; 127.0.0.1
keeps the tests self-contained and off the LAN.
TestInitialise_MulticastMode_InvalidDataPort was passing for the wrong
reason: UDPStreamer.cpp rejected it on the missing Interface before the
DataPort == Port check could run. It now proves what its name claims.
TestExecute_MulticastConnectDataDisconnect additionally needed the
two-argument Join(): the single-argument form passes INADDR_ANY, so the
reader joined the default-route interface while the server sent on
loopback via IP_MULTICAST_IF, and the DATA datagram never arrived.
GTest: 132/132 (was 128/132), multicast subset stable over 3 runs.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
