验证：根据域名获取对应的IP地址（gethostbyname）？

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我是靠谱客的博主光亮唇彩，最近开发中收集的这篇文章主要介绍验证：根据域名获取对应的IP地址（gethostbyname）？，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

有时候，总想验证一些奇怪的想法，干脆就写下来，以备后查。

想法：根据域名获取对应的IP地址（gethostbyname）？

// 获取域名对应的IP地址
BOOL GetIpAddrByDomainName(LPCTSTR domain, CAtlArray<CString> & ipList)
{
	WSADATA wsadata;
	WSAStartup(MAKEWORD(2, 2), &wsadata);
	assert(LOBYTE(wsadata.wVersion) == 2 && HIBYTE(wsadata.wVersion) == 2);

	HOSTENT *hptr = gethostbyname(CStringA(domain));
	if (NULL == hptr)
	{
		return FALSE;
	}
	assert(AF_INET == hptr->h_addrtype || AF_INET6 == hptr->h_addrtype);

	BOOL exist = FALSE;
	TCHAR ipStr[INET6_ADDRSTRLEN] = {0};
	
	for (char **pptr = hptr->h_addr_list; *pptr != NULL; pptr++)
	{
		if (NULL != InetNtop(hptr->h_addrtype, *pptr, ipStr, sizeof(ipStr)))
		{
			exist = TRUE;
			ipList.Add(ipStr);
		}
	}
	
    return exist;
}

// 测试域名解析
void TestCase_GetIpAddrByDomainName()
{
	LPCTSTR domains[] = {
		_T("localhost"),
		_T("baidu.com"),
		_T("www.baidu.com"),
		_T("1.2.3.4"),
		_T("0.0.0.0"),
		_T("127.0.0.1"),
		_T("ABCD:EF:1:2:3:4:5:6789"),
		_T("::1"),
		NULL,
		_T(""),
		_T("this is a string.")
	};

	for (unsigned int i = 0; i < _countof(domains); i++)
	{
		CAtlArray<CString> ipList;

		if (! GetIpAddrByDomainName(domains[i], ipList))
		{
			_tprintf_s(_T("get IP address from domain name failed. [%s] n"), domains[i]);
		}
		else
		{
			CString csIpList;
			for (unsigned int k = 0; k < ipList.GetCount(); k++)
			{
				csIpList += ipList[k];
				if (k != ipList.GetCount() - 1)
				{
					csIpList += _T(",");
				}
			}
			_tprintf_s(_T("get IP address from domain name success. [%s] [%s] [%u] n"), domains[i], csIpList, ipList.GetCount());
		}
	}
}

执行结果：

Visual Leak Detector Version 2.5.1 installed.
get IP address from domain name success. [localhost] [127.0.0.1] [1]
get IP address from domain name success. [baidu.com] [123.125.115.110,220.181.57.216] [2]
get IP address from domain name success. [www.baidu.com] [180.97.33.108,180.97.33.107] [2]
get IP address from domain name success. [1.2.3.4] [1.2.3.4] [1]
get IP address from domain name success. [0.0.0.0] [0.0.0.0] [1]
get IP address from domain name success. [127.0.0.1] [127.0.0.1] [1]
get IP address from domain name failed. [ABCD:EF:1:2:3:4:5:6789]
get IP address from domain name failed. [::1]
get IP address from domain name success. [(null)] [172.28.206.65,192.168.233.1,192.168.43.1,192.168.111.161] [4]
get IP address from domain name success. [] [172.28.206.65,192.168.233.1,192.168.43.1,192.168.111.161] [4]
get IP address from domain name failed. [this is a string.]
No memory leaks detected.

注意：

1. 传递IPv4字符串，得到的仍然IPv4字符串。

2. 传递IPv6字符串，解析失败。

3. 传递NULL和空字符串，得到的都是本地IP地址列表。

4. baidu.com和www.baidu.com得到的IP地址列表不一样。