linker error for ns_initparse

Question

Here the code

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <netinet/in.h>
#include <resolv.h>

int main (int argc, char *argv[])
{
    u_char nsbuf[4096];
    char dispbuf[4096];
    ns_msg msg;
    ns_rr rr;
    int i, j, l;

    if (argc < 2) {
        printf ("Usage: %s <domain>[...]\n", argv[0]);
        exit (1);
    }

    for (i = 1; i < argc; i++) {
        l = res_query (argv[i], ns_c_any, ns_t_mx, nsbuf, sizeof (nsbuf));
        if (l < 0) {
            perror (argv[i]);
        } else {
#ifdef USE_PQUERY

/* this will give lots of detailed info on the request and reply */

            res_pquery (&_res, nsbuf, l, stdout);
#else

/* just grab the MX answer info */

            ns_initparse (nsbuf, l, &msg);
            printf ("%s :\n", argv[i]);
            l = ns_msg_count (msg, ns_s_an);
            for (j = 0; j < l; j++) {
                ns_parserr (&msg, ns_s_an, j, &rr);
                ns_sprintrr (&msg, &rr, NULL, NULL, dispbuf, sizeof (dispbuf));
                printf ("%s\n", dispbuf);
            }
#endif
        }
    }

    exit (0);
}

I compile it as

gcc dns.c -lresolv

and I get the following linker error

In function main': dns.c:(.text+0xd5): undefined reference to__ns_initparse' dns.c:(.text+0x130): undefined reference to __ns_parserr' dns.c:(.text+0x16a): undefined reference to__ns_sprintrr'

Help

From some quick googling, it appears that these functions are considered internal and therefore deliberately not exported. They may be present in the static library. This is also probably version-dependent; there have been plenty of versions of the BIND API. http://jira.secondlife.com/browse/VWR-1598 and http://www.newsgroups-index.com/group/linux_-debian_-maint_-glibc_l361.html — Cascabel, Nov 06 '09 at 17:17

score 5 · Answer 1 · edited Feb 26 '19 at 09:48

5

Linking with the resolver library helped fixed his issue for me, I added -lresolv to my compilation command.

edited Feb 26 '19 at 09:48

sdgfsdh

33,689
26
132
245

answered Nov 19 '17 at 19:39

aileronajay

128
1
9

I have the same error as OP when compiling, but adding `-lresolv` did not solve it for me. My command is `g++ -o test -x c++ -std=c++20 -lresolv ./test-resolv.cpp`, any idea what I'm doing wrong? – Guss Jun 27 '23 at 12:48
NM, I Solved my problem, it was pretty silly: the `-l` commands must come after the source reference (something about the order in which the linked loads libraries from `-l` to resolve references). – Guss Jun 27 '23 at 12:52

score 0 · Answer 2 · answered Oct 24 '15 at 23:07

0

I believe you need to add

#include <arpa/nameser.h>

to your file

answered Oct 24 '15 at 23:07

Darakian

619
2
9
22

This will not work since a header cannot define a reference. – sdgfsdh Feb 26 '19 at 09:49

linker error for ns_initparse

2 Answers2

Linked