Description:

getaddrinfo() returns IPv4 addresses instead of IPv4-mapped IPv6 addresses (when AI_V4MAPPED|AI_ALL is set), despite the AF_INET6 family requirement in the hints structure.

The attached file (gaitest.c) is a trivial test case that exhibits this bug. Try ./gaitest some.ipv4.host. It will return IPv4 addresses instead of the requested IPv4-mapped IPv6 addresses. This contradicts the information in the man page.

This issue has existed for >1 year, AFAIK. However, it became more obvious in some pieces of code I currently work with. Applications that simply rely on the address type being always AF_INET6 (as promised by the man page) can have weird issues and crashes caused by this non-standard getaddrinfo() behavior.

Additional info:

* package version(s)

glibc 2.13-4
(The issue has existed for >1 year, AFAIK, so the exact glibc version may not matter.)

* config and/or log files etc.

Config files are listed in this bug's description: https://bugs.archlinux.org/task/23052
Identical files were used in this case. (And again, multiple versions of /etc/gai.conf, including an empty one, were tested.)

Steps to reproduce:

Resolve a host name that translates to (at least one) IPv4 address using the attached code snippet.