Windows apparently has special code to deal with those addresses. If all
your network interfaces are up and have acquired addresses, then the
link-local network at 169.254.0.0/16 is unreachable. I had never caught
this because both my Windows VM and my bare metal Windows have inactive
interfaces (like the Bluetooth PAN one) and, when inactive, Windows
assigns a link-local address. But in the CI, the interface(s) were all
up and running, causing this issue.
Unix systems don't treat IPv4 link-local any differently, so they always
worked, so long as any interface was up and there had to be one to reach
the network test server.
This commit reworks the test to add test addresses based on the
addresses found on up & running interfaces (see tst_qudpsocket.cpp). For
IPv4, we flip the bits in the local portion of the address. For IPv6, we
add a node with an address I generated randomly (non-universal), with
the same scope.
Fixes: QTBUG-65667
Change-Id: I568dea4813b448fe9ba6fffd15dd9f482db34991
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
c4b0ff4855