[Bug 52133] New: winhttp/wininet should not query mDNS for proxy auto-detection

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=52133

            Bug ID: 52133
           Summary: winhttp/wininet should not query mDNS for proxy
                    auto-detection
           Product: Wine
           Version: 6.22
          Hardware: x86-64
                OS: Mac OS X
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: winhttp
          Assignee: wine-bugs at winehq.org
          Reporter: bshanks at codeweavers.com

At least on macOS, the default hostname is something like
"XXs-MacBook-Pro.local". Wine then (correctly) reads the domain name as
"local".

When winhttp or wininet tries to use DNS proxy auto-detection (i.e.
WinHttpDetectAutoProxyConfigUrl() with the WINHTTP_AUTO_DETECT_TYPE_DNS_A
option), they try to resolve "wpad.local".

On macOS this hangs for 5 seconds before failing, causing a 10-minute long hang
while launching Halo: MCC.

This also opens a security hole by allowing anyone on the local network to
advertise an HTTP proxy that will be used automatically by other hosts on the
network.

Microsoft has disabled link-local name resolution (i.e. NetBIOS, LLMNR, mDNS)
by default for WPAD for years:
https://bugs.chromium.org/p/chromium/issues/detail?id=1176970#c29

This is done on Windows with the undocumented AI_DNS_ONLY flag to
getaddrinfo(), unfortunately there is no equivalent UNIX flag.
Adding a special-case for ".local" domains would at least prevent the most
common case of mDNS resolution.

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