On 01/03/2010 15:40, Robert Milkowski wrote:
On 26/02/2010 00:52, Shawn Walker wrote:
On 02/25/10 06:03 PM, Robert Milkowski wrote:
Hi,
mi...@vault:~$ cat dns.c
#include<stdlib.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<arpa/nameser.h>
#include<resolv.h>
#include<netdb.h>
int main(int argc, char **argv)
{
res_init();
if (!_res.nscount) {
fprintf(stderr,"No nameservers defined.\n");
exit(1);
}
}
mi...@vault:~$ gcc -o dns -lresolv -lsocket -lnsl dns.c
...
it works fine on b111 but fails on b132 and b133 (I haven't tested
any other builds).
Did you check _res.res_h_errno? I would note that res_init() is
deprecated.
If an error is encountered during res_init()'s initial logic, it will
effectively set nscount to 0 because it sets maxns = 0. [1]
well, _res.res_h_errno is returning with 0 while nscount is 0 as well.
deprecated or not that's what some programs are using (like mtr) and
something changed post 111b so it stopped working.
I could get mtr fixed but really the problem has to be founded as it
might impact other programs too.
Will try to dig more deeply once I've got some time.
I think I found where the issue is.
On 11th of November 2009 there was an integration of 11038:74b12212b8a2
<http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/lib/libresolv2/common/resolv/res_data.c?r=11038%3A74b12212b8a2>
It introduced changes to
/onnv/onnv-gate/usr/src/lib/libresolv2/common/resolv/res_data.c
<http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/lib/libresolv2/common/resolv/res_data.c>
http://src.opensolaris.org/source/diff/onnv/onnv-gate/usr/src/lib/libresolv2/common/resolv/res_data.c?r2=%252Fonnv%252Fonnv-gate%252Fusr%252Fsrc%252Flib%252Flibresolv2%252Fcommon%252Fresolv%252Fres_data.c%4011038%3A74b12212b8a2&r1=%252Fonnv%252Fonnv-gate%252Fusr%252Fsrc%252Flib%252Flibresolv2%252Fcommon%252Fresolv%252Fres_data.c%400%3A68f95e015346
In particular it added below three lines:
94#if defined(DO_PTHREADS) || defined(__linux)
95#define _res (*__res_state())
96#endif
97
If I comment them out and LD_PRELOAD libresolve.so.2 library then my
test program works fine.
So looks like the above change broke the old behavior.
--
Robert Milkowski
http://milek.blogspot.com
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