TIL gethostbyname*() and gethostbyaddr*() functions are obsolete

It wasn’t obvious to me until I tried to run netcat utility (aka nc) on Ubuntu 10.04 (lucid) release to check Zookeeper’s status:

echo "stat" | nc zookeer_server_name 2181
zookeer_server_name: forward host lookup failed: No address associated with name

It wouldn’t have been a problem had Zookeeper server used IPv4 address but it was configured with IPv6. So tools that used gethostbyname2(), e.g. getent, were still ok, and only those with gethostbyname() were failing me. Luckily, netcat and other important libraries had newer versions I could use. Once again, if you are on an old and rusty Linux distro be aware that gethostbyname*() and gethostbyaddr*() functions are obsolete

As Anton mentioned in his comment below, getaddrinfo() had its own gotchas, which, if I got it right, were caused by AI_ADDRCONFIG flag. There is a good summary page which goes in more details regarding AI_ADDRCONFIG and the peculiarities pertaining to its current implementation in glibc.

Posted on January 28, 2017 at 11:54 am by sergeyt · Permalink
In: Linux, TIL

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  1. Written by Anton
    on January 28, 2017 at 8:54 pm
    Reply ·