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

问题描述

我写就是要我的MX记录做一个DNS查找的应用程序。我不知道，如果任何人有经验做这种工作，但如果你这样做，任何帮助，将AP preciated。

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：
我要去的事情是，将发送一封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的MX记录的域。

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

最简单的方法是简单地使用常用的工具。

The simplest method is to simply use commonly available tools.

基本挖命令将通过该查询返回的记录，您：

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

dig mx example.com

如果你只想与MX记录的行...

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

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

挖可在大多数Linux / Unix服务器。

dig is available on most linux / unix boxes.

如果你在Windows中可以使用nslookup

If you're on windows you can use nslookup

nslookup -type=mx example.com

然后就解析这些常用工具的输出。

Then just parse the output of these common tools.

既然你把C作为一个标签，我猜你正在寻找源$ C ​​$ C做使用原始套接字MX查找。我复制这从<一个href=\"http://www.developerweb.net/forum/showthread.php?t=3550\">http://www.developerweb.net/forum/showthread.php?t=3550.这可能是更你在找什么？

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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