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Hi, |
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|
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I'm having some issues wih resolving of the loopback ip address with |
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glibc's gethostbyaddr() / getnameinfo(). |
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|
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I have a setup with the following (abbreviated) /etc/hosts file: |
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|
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==8<================ |
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::1 ip6-localhost |
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127.0.0.1 localhost |
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==8<================ |
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|
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When using gethostbyaddr() or getnameinfo() to resolve ip address |
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127.0.0.1, the hostname "ip6-localhost" is returned, but I expected to |
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see "localhost". |
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|
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When editing /etc/hosts and putting the 127.0.0.1 above the ::1 line, |
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things work normally. |
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|
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It seems that glibc treats the loopback ip addresses (127.0.0.1 and ::1) |
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as a special case, and returns the first entry from the hosts file for |
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any loopback address, making no difference between ipv4 and ipv6. I |
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would expect libc to differ between the 2 addresses, but it seems it |
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doesn't. |
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|
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However: I find no documentation in man pages or google saying that the |
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loopback addresses receive a special treatment, or that the entries in |
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the hosts file should be in some special order to make things work as |
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expected. |
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|
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I can easily reproduce this on several gentoo hosts, running |
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glibc-2.10.1-r1 or glibc-2.9_p20081201-r2, and also on ubuntu 9.04 |
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(libc6 version 2.9-4ubuntu6) and 9.10 (2.10.1-0ubuntu15). |
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|
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Could someone explain to me if this is intended behaviour, and why, as I |
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tend to see this more as a bug? |
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|
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-- |
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Regards, |
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Tom |
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|
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PS: I tested this by using the name-addr-test utils provided by postfix |
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(2.6.5 tarball, auxiliary/name-addr-test/ dir), because postfix was the |
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application that showed me this strange behaviour and the test utils |
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were readily available. |
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|
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PS2: When you want to reproduce this, no actual ipv6 connectivity is |
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needed. Since glibc supports ipv6 out of the box, this should 'work' |
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with any setup. |
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