The getaddrinfo function correctly returns EAI_AGAIN for AF_INET and AF_INET6 queries that have timed out. However, for AF_UNSPEC, a defect in the library caused EAI_NONAME to be returned. Applications could incorrectly interpret EAI_NONAME as there being no result, when they should have tried the query again. The defect has been corrected such that an EAI_AGAIN is returned to the caller instead of EAI_NONAME.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://rhn.redhat.com/errata/RHSA-2015-2199.html
Description of problem: getaddrinfo returns EAI_NONAME when it should EAI_AGAIN, like when DNS query times out. It is also a question what should it return when no DNS is configured in resolv.conf and the hostname is also not in /etc/hosts; currently it rerurns also EAI_NONAME. Version-Release number of selected component (if applicable): glibc-2.12-1.132.el6 How reproducible: always Steps to Reproduce: [root@rhel6 audit]# cat getaddrinfo.c #include <stdio.h> #include <string.h> #include <stdlib.h> #include <netdb.h> #include <sys/types.h> #include <sys/socket.h> #include <arpa/inet.h> int lookup_host (const char *host) { struct addrinfo hints, *res; int errcode; char addrstr[100]; void *ptr; memset (&hints, 0, sizeof (hints)); hints.ai_family = PF_UNSPEC; hints.ai_socktype = SOCK_STREAM; hints.ai_flags |= AI_CANONNAME; errcode = getaddrinfo (host, NULL, &hints, &res); if (errcode != 0) { printf ("Error num: %d\n", errcode); printf ("Error def: %s\n", gai_strerror(errcode)); perror ("getaddrinfo"); return -1; } printf ("Host: %s\n", host); while (res) { inet_ntop (res->ai_family, res->ai_addr->sa_data, addrstr, 100); switch (res->ai_family) { case AF_INET: ptr = &((struct sockaddr_in *) res->ai_addr)->sin_addr; break; case AF_INET6: ptr = &((struct sockaddr_in6 *) res->ai_addr)->sin6_addr; break; } inet_ntop (res->ai_family, ptr, addrstr, 100); printf ("IPv%d address: %s (%s)\n", res->ai_family == PF_INET6 ? 6 : 4, addrstr, res->ai_canonname); res = res->ai_next; } return 0; } int main (int argc, char *argv[]) { if (argc < 2) exit (1); return lookup_host (argv[1]); } [root@rhel6 audit]# [root@rhel6 audit]# [root@rhel6 audit]# [root@rhel6 audit]# gcc -o getaddrinfo getaddrinfo.c [root@rhel6 audit]# ./getaddr getaddr getaddrinfo [root@rhel6 audit]# cat /etc/resolv.conf nameserver 127.0.0.1 [root@rhel6 audit]# cat /var/named/bbb $TTL 86400 ; 24 hours could have been written as 24h or 1d $ORIGIN bbb.net. @ 1D IN SOA rhel6.bbb.net. hostmaster.bbb.net. ( 2002022401 ; serial 3H ; refresh 15 ; retry 1w ; expire 3h ; minimum ) IN NS rhel6.bbb.net. ; in the domain IN A 192.168.100.60 ;name server definition rhel6 IN A 192.168.100.60 ;name server definition rhel61 IN A 192.168.100.61 ;name server definition [root@rhel6 audit]# [root@rhel6 audit]# ./getaddrinfo rhel61.bbb.net Host: rhel61.bbb.net IPv4 address: 192.168.100.61 (rhel61.bbb.net) [root@rhel6 audit]# [root@rhel6 audit]# iptables -A OUTPUT -m udp -p udp --sport 53 -j REJECT [root@rhel6 audit]# ./getaddrinfo rhel61.bbb.net Error num: -2 Error def: Name or service not known getaddrinfo: Connection timed out [root@rhel6 audit]# [root@rhel6 audit]# rpm -q glibc glibc-2.12-1.132.el6.x86_64 glibc-2.12-1.132.el6.i686 [root@rhel6 audit]# Actual results: EAI_NONAME Expected results: EAI_AGAIN