Bug#582916: libc6: getaddrinfo() returns EAI_NONAME for temporary problem.
see the same here under specific circumstances:
to reproduce the following test (see also the comments):
/*BINFMTC:
test for getaddrinfo bug:
getaddrinfo returns EAI_NONAME when it should return EAI_EAGAIN
getaddrinfo returns EAI_NONAME when it should return EAI_EAGAIN for
hosts with A but no record and there is packet loss and/or a an
overloaded dns server
to easily reproduce, fake packet loss/overloaded dns server
on linux do something like:
# iptables -I OUTPUT -p udp -m udp --dport 53 -j DROP
# iptables -I OUTPUT -p udp -m udp --dport 53 -j LOG --log-prefix DROP DNS
REQUEST
# iptables -I OUTPUT -p udp -m udp --dport 53 -m limit --limit 10/sec -j
ACCEPT
first
*/
#include sys/types.h
#include sys/socket.h
#include netdb.h
#include stdio.h
#include stdlib.h
struct addrinfo hints; // all 0
int main(int argc, char** argv) {
struct addrinfo* res;
int i;
hints.ai_family = AF_INET;
/* should work on mosts setups
(there is another bug involving mdns
if it fails try to replace the hosts line in /etc/nsswitch.conf
with something like:
hosts: files dns
)
*/
for(i=0;i1000;++i) {
/* test host must have a A record but no record */
int r=getaddrinfo(karme.de,0,hints,res);
if(!((r==0)||(r==EAI_AGAIN))) {
printf(%s:%d: error: r=%d %s\n,__FILE__,__LINE__,r,gai_strerror(r));
exit(EXIT_FAILURE);
}
if (!r) freeaddrinfo(res);
}
/* this will fail sometimes
what happens?
DNS request for A record is sent but no answer is received
DNS request for record is sent and answer without entries received
now getaddrinfo returns EAI_NONAME when in fact it should return EAI_AGAIN
*/
hints.ai_family = AF_UNSPEC;
for(i=0;i1000;++i) {
int r=getaddrinfo(karme.de,0,hints,res);
if(!((r==0)||(r==EAI_AGAIN))) {
printf(%s:%d: error: r=%d %s\n,__FILE__,__LINE__,r,gai_strerror(r));
exit(EXIT_FAILURE);
}
if (!r) freeaddrinfo(res);
}
return EXIT_SUCCESS;
}
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Bug#582916: Info received (Bug#582916: libc6: getaddrinfo() returns EAI_NONAME for temporary problem.)
updated test:
/*BINFMTC: -Wall -Wextra -Wno-unused-parameter
test for getaddrinfo bug:
getaddrinfo returns EAI_NONAME when it should return EAI_EAGAIN
getaddrinfo returns EAI_NONAME when it should return EAI_EAGAIN for
hosts with A but no record and there is packet loss and/or a an
overloaded dns server
to easily reproduce, fake packet loss/overloaded dns server
on linux do something like:
# iptables -I OUTPUT -p udp -m udp --dport 53 -j DROP
# iptables -I OUTPUT -p udp -m udp --dport 53 -j LOG --log-prefix DROP DNS
REQUEST
# iptables -I OUTPUT -p udp -m udp --dport 53 -m limit --limit 10/sec -j
ACCEPT
first
*/
#include sys/types.h
#include sys/socket.h
#include netdb.h
#include stdio.h
#include stdlib.h
/* test host must have a A record but no record
also note the final dot - otherwise a search entry in
resolv.conf might cause the first test to fail, too */
const char* host=karme.de.;
struct addrinfo hints; // all 0
int main(int argc, char** argv) {
struct addrinfo* res;
int i;
hints.ai_family = AF_INET;
/* first test should work on mosts setups
(there is another bug involving mdns
if it fails try to replace the hosts line in /etc/nsswitch.conf
with something like:
hosts: files dns
)
*/
for(i=0;i1000;++i) {
int r=getaddrinfo(host,0,hints,res);
if(!((r==0)||(r==EAI_AGAIN))) {
printf(%s:%d: error: r=%d %s\n,__FILE__,__LINE__,r,gai_strerror(r));
exit(EXIT_FAILURE);
}
if (!r) freeaddrinfo(res);
}
/* second test will fail sometimes
what happens?
DNS request for A record is sent but no answer is received
DNS request for record is sent and answer without entries received
now getaddrinfo returns EAI_NONAME when in fact it should return EAI_AGAIN
*/
hints.ai_family = AF_UNSPEC;
for(i=0;i1000;++i) {
int r=getaddrinfo(host,0,hints,res);
if(!((r==0)||(r==EAI_AGAIN))) {
printf(%s:%d: error: r=%d %s\n,__FILE__,__LINE__,r,gai_strerror(r));
exit(EXIT_FAILURE);
}
if (!r) freeaddrinfo(res);
}
return EXIT_SUCCESS;
}
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Bug#582916: libc6: getaddrinfo() returns EAI_NONAME for temporary problem.
similar report upstream: http://sourceware.org/bugzilla/show_bug.cgi?id=12994 -- To UNSUBSCRIBE, email to debian-glibc-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/87pq3xz4sw.fsf...@karme.de
Bug#582916: libc6: getaddrinfo() returns EAI_NONAME for temporary problem.
Package: libc6 Version: 2.10.2-6 Severity: important Hi, It seems that getaddrinfo() now returns EAI_NONAME for a non-permanent error. Trying to resolve something using host or dig, I get as error: ;; connection timed out; no servers could be reached That is clearly different that an error message like: Host host not found: 3(NXDOMAIN) For that error I would expect to get EAI_NONAME. In case I don't get a reply, I would expect to get back EAI_AGAIN. The version in lenny still returns EAI_AGAIN. Kurt -- To UNSUBSCRIBE, email to debian-glibc-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20100524141000.ga16...@roeckx.be
