[英]How to query a server and get the MX, A, NS records
I'm trying to get the A, MX and NS A server record as follows:我正在尝试获取 A、MX 和 NSA 服务器记录,如下所示:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <netinet/in.h>
#include <resolv.h>
#include <netdb.h>
#define N 4096
int main (int argc, char *argv[])
{
u_char nsbuf[N];
char dispbuf[N];
ns_msg msg;
ns_rr rr;
int i, l;
if (argc < 2) {
printf ("Usage: %s <domain>\n", argv[0]);
exit (1);
}
// HEADER
printf("Domain : %s\n", argv[1]);
// ------
// A RECORD
printf("A records : \n");
l = res_query(argv[1], ns_c_any, ns_t_a, nsbuf, sizeof(nsbuf));
if (l < 0)
{
perror(argv[1]);
}
ns_initparse(nsbuf, l, &msg);
l = ns_msg_count(msg, ns_s_an);
for (i = 0; i < l; i++)
{
ns_parserr(&msg, ns_s_an, 0, &rr);
ns_sprintrr(&msg, &rr, NULL, NULL, dispbuf, sizeof(dispbuf));
printf("\t%s \n", dispbuf);
}
//------------
// MX RECORD
printf("MX records : \n");
l = res_query(argv[1], ns_c_any, ns_t_mx, nsbuf, sizeof(nsbuf));
if (l < 0)
{
perror(argv[1]);
}
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);
l = ns_msg_count(msg, ns_s_an);
for (i = 0; i < l; i++)
{
ns_parserr(&msg, ns_s_an, i, &rr);
ns_sprintrr(&msg, &rr, NULL, NULL, dispbuf, sizeof(dispbuf));
printf ("\t%s\n", dispbuf);
}
#endif
}
// ---------
// NS RECORD
printf("NS records : \n");
l = res_query(argv[1], ns_c_any, ns_t_ns, nsbuf, sizeof(nsbuf));
if (l < 0)
{
perror(argv[1]);
}
ns_initparse(nsbuf, l, &msg);
l = ns_msg_count(msg, ns_s_an);
for (i = 0; i < l; i++)
{
ns_parserr(&msg, ns_s_an, 0, &rr);
ns_sprintrr(&msg, &rr, NULL, NULL, dispbuf, sizeof(dispbuf));
printf("\t%s \n", dispbuf);
}
// ---------
return 0;
}
On request receive a lot of the same, that is, the same A records.根据请求收到很多相同的,即相同的 A 记录。 The same with the NS records.与 NS 记录相同。 What am I doing wrong?我究竟做错了什么? Example:例子:
Domain : mail.ru
A records :
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
mail.ru. 22S IN A 94.100.191.207
MX records :
mail.ru. 1m57s IN MX 10 mxs.mail.ru.
NS records :
mail.ru. 1m50s IN NS ns.mail.ru.
mail.ru. 1m50s IN NS ns.mail.ru.
mail.ru. 1m50s IN NS ns.mail.ru.
mail.ru. 1m50s IN NS ns.mail.ru.
mail.ru. 1m50s IN NS ns.mail.ru.
mail.ru. 1m50s IN NS ns.mail.ru.
Please help.请帮忙。
In this call: 在这个电话中:
ns_parserr(&msg, ns_s_an, 0, &rr);
The third argument is the index of the record you want to retrieve. 第三个参数是要检索的记录的索引。 So in your case it should be: 所以在你的情况下它应该是:
ns_parserr(&msg, ns_s_an, i, &rr);
Just tried your code with that minor fix, and it works as expected: 刚尝试使用那个小修补程序的代码,它按预期工作:
Domain : mail.ru
A records :
mail.ru. 5S IN A 94.100.191.248
mail.ru. 5S IN A 94.100.191.249
mail.ru. 5S IN A 94.100.191.250
mail.ru. 5S IN A 94.100.191.201
mail.ru. 5S IN A 94.100.191.202
mail.ru. 5S IN A 94.100.191.203
mail.ru. 5S IN A 94.100.191.204
mail.ru. 5S IN A 94.100.191.205
mail.ru. 5S IN A 94.100.191.206
mail.ru. 5S IN A 94.100.191.207
mail.ru. 5S IN A 94.100.191.208
mail.ru. 5S IN A 94.100.191.209
mail.ru. 5S IN A 94.100.191.210
mail.ru. 5S IN A 94.100.191.241
mail.ru. 5S IN A 94.100.191.242
mail.ru. 5S IN A 94.100.191.243
mail.ru. 5S IN A 94.100.191.244
mail.ru. 5S IN A 94.100.191.245
mail.ru. 5S IN A 94.100.191.246
mail.ru. 5S IN A 94.100.191.247
MX records :
mail.ru. 7m14s IN MX 10 mxs.mail.ru.
NS records :
mail.ru. 3m35s IN NS ns2.mail.ru.
mail.ru. 3m35s IN NS ns.mail.ru.
mail.ru. 3m35s IN NS ns4.mail.ru.
mail.ru. 3m35s IN NS ns5.mail.ru.
mail.ru. 3m35s IN NS ns1.mail.ru.
mail.ru. 3m35s IN NS ns3.mail.ru.
With Ubuntu 20.04 and more,使用 Ubuntu 20.04 及以上,
res_query(argv[1], ns_c_any, ns_t_mx, nsbuf, sizeof(nsbuf));
fail.失败。 Please replace ns_c_any by ns_c_in请用 ns_c_in 替换 ns_c_any
res_query(argv[1], ns_c_in, ns_t_mx, nsbuf, sizeof(nsbuf));
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