Work around glibc getaddrinfo PTR lookups In krb5_sname_to_principal(), we always do a forward canonicalization using getaddrinfo() with AI_CANONNAME set. Then, we do a reverse canonicalization with getnameinfo() if rdns isn't set to false in libdefaults. Current glibc (tested with eglibc 2.11.1) has the arguably buggy behavior of doing PTR lookups in getaddrinfo() to get the canonical name, if hints.ai_family is set to something other than AF_UNSPEC. This behavior defeats the ability to turn off rdns. Work around this behavior by using AF_UNSPEC in krb5_sname_to_principal() from the start, instead of starting with AF_INET and falling back. Specify AI_ADDRCONFIG to avoid AAAA lookups on hosts with no IPv6 addresses. (cherry picked from commit bc8594e7c388c8a5cfb9516a0980877cb1321d32) In sn2princ, getaddrinfo without AI_ADDRCONFIG When canonicalizing a principal, use AI_CANONNAME alone in the hint flags for getaddrinfo, for two reasons. First, it works around a gnu libc bug where getaddrinfo does a PTR lookup for the canonical name (we tried to work around this in r24977 bug the addition of AI_ADDRCONFIG caused the same problem as the use of AF_INET). Second, an IPv4-only host should be able create a principal for an IPv6-only host even if it can't contact the host. This does result in extra AAAA queries in the common case (IPv4-only host contacting IPv4-only service), which is unfortunate. But we need to leave that optimization up to the platform at this point. (cherry picked from commit c3ab5fe0b01a68b14d5657740006488721b48b7b) https://github.com/krb5/krb5/commit/e07cb2720551eaf1369ab388e8db61ee41c51c5b Author: Greg Hudson Committer: Tom Yu Commit: e07cb2720551eaf1369ab388e8db61ee41c51c5b Branch: krb5-1.9 src/lib/krb5/os/sn2princ.c | 7 ------- 1 files changed, 0 insertions(+), 7 deletions(-)