[BUG] NSCD fails to collect all the available IP addresses for a host

[suzuki <suzuki at in dot ibm dot con>]

Hi,

I came across a problem with the gethostbyname()/getaddrinfo(), where 
these functions failed to return all the addresses available for a 
particular host from /etc/hosts. Upon debugging I could find that this 
problem happens only when we run nscd daemon.

Here is the configuration details :

* /etc/nsswitch.conf has the hosts lookup priority as hosts,dns

* /etc/host.conf have the multi directive turned on.

* /etc/hosts have two IPs associated with the same host name.

The above functions returns all the addresses, if I stop the nscd daemon.

Upon debugging, I could find that the problem lies in 
__nss_files_get_hostbyname2_r / __nss_files_get_hostbyname_r .

while ((status = internal_getent (result, buffer, buflen, errnop
                                 H_ERRNO_ARG EXTRA_ARGS_VALUE))   			== 
NSS_STATUS_SUCCESS)
      { break_if_match } 
        if (status == NSS_STATUS_SUCCESS
     && _res_hconf.flags & HCONF_FLAG_MULTI)

Even though we check for HCONF_FLAG_MULTI in _res_hconf.flags, the 
_res_hconf is not initialized when we check the same. I tried adding,

+ if (!_res_hconf.initialized)
+   _res_hconf_init();

to fix the problem, but when I tried to build the libc, the build failed 
with unable to resolve the symbol _res_hconf_init().

I also tried defining :

#define NEED__RES_HCONF for nscd daemon code, which again lead to the 
above compilation error.


Could you please share your thoughts about the issue and how to fix the 
same ?

Thanks

Suzuki K P
Linux Technology Center
IBM Software Labs