[Webkit-unassigned] [Bug 51783] New: Fallback to IPv4 does not work on dual-stack pages (IPv6 + IPv4)

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=51783

           Summary: Fallback to IPv4 does not work on dual-stack pages
                    (IPv6 + IPv4)
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: PC
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: Page Loading
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: michael+webkit at stapelberg.de


Created an attachment (id=77729)
 --> (https://bugs.webkit.org/attachment.cgi?id=77729&action=review)
strace logfile of luakit michael.stapelberg.de

When having not-working IPv6 connectivity (properly configured system but requests result in 'Network unreachable'), Webkit (I tried with luakit and midori) displays an error instead of retrying with IPv4.

To reproduce, test on a system with native IPv6 connectivity (or at least tunneled on a different host, so that the system you test on thinks it’s natively connected). Using getaddrinfo(3) to resolve an IPv6-enabled host (for example with the attached getaddrinfo.c example) should result in the following output:

michael.stapelberg.de resolved to 2001:4d88:1008:3::ae1
michael.stapelberg.de resolved to 212.86.204.165

Now configure your system to simulate not being able to reach the IPv6 address:

# ip6tables -I OUTPUT 1 -d 2001:4d88:1008:3::ae1 -j REJECT --reject-with icmp6-addr-unreachable

Then start 'luakit michael.stapelberg.de'. You will see an error page, but the site itself is still reachable via IPv4. Use for example 'wget http://michael.stapelberg.de -O/dev/null' to confirm that other tools handle this case correctly.

I’ve attached a complete strace file of 'luakit michael.stapelberg.de'.

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