从DNS服务器拉取MX记录 [英] Pulling MX record from DNS server

问题描述

我正在编写一个需要我对MX记录进行DNS查找的应用程序。我不知道有没有人有做过这样的工作的经验，但如果你这样做，任何帮助将不胜感激。

I am writing an application that is requiring me to do a DNS lookup for an MX record. I'm not sure if anyone has had experience doing this kind of work but if you do, any help would be appreciated.

编辑：
我要去的是一个将发送电子邮件警报的应用程序。问题是我需要让应用程序能够查找一个域的MX记录。

The thing that I'm going for is an application that will send an e-mail alert. The problem is I need to have the application be able to lookup the MX record for a domain.

推荐答案

最简单的方法是只需使用常用的工具。

The simplest method is to simply use commonly available tools.

基本的dig命令将通过此查询将记录返回给您：

The basic "dig" command will return the records to you via this query:

dig mx example.com

如果你只想线条与mx记录...

If you want just the lines with the mx records...

dig mx example.com | grep -v '^;' | grep example.com

dig在大多数linux / unix框上都可用。

dig is available on most linux / unix boxes.

如果你在Windows上，可以使用nslookup

If you're on windows you can use nslookup

nslookup -type=mx example.com

然后只需解析这些常见工具的输出。

Then just parse the output of these common tools.

由于您将C作为标签，我想您正在寻找源代码使用原始套接字的MX查找。我将其从 http://www.developerweb.net/forum/showthread.php ΔT= 3550 。可能更多的是您要查找的内容？

Since you put "C" as a tag, I guess you're looking for source code to do MX lookups using raw sockets. I copied this from http://www.developerweb.net/forum/showthread.php?t=3550. It may be more what you're looking for?

#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);
}

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