Utility.h

#pragma once
class CUtility
{
public:
       CUtility();
       ~CUtility();

public:
        DWORD HttpGet( LPCTSTR lpszFullUrl, char *pBuffer, int iBufferSize);
        void GetPublicIp( TCHAR *pIP, int len);
};

Utility.cpp

#include "stdafx.h"
#include "Utility.h"
#include "Transcode.h"
#include<wininet.h>
#pragma comment (lib ,"wininet.lib" )  


CUtility::CUtility()
{
}


CUtility::~CUtility()
{
}

void CUtility ::GetPublicIp(TCHAR *pIP, int len)
{
        char szBuffer[1024];
       memset(szBuffer, 0, sizeof( char) * 1024);
       HttpGet( _TEXT( "http://city.ip138.com/ip2city.asp" ), szBuffer, 1024);

        char* begin = strstr(szBuffer, "[")+1;
        char* end = strstr(begin, "]");
        int offset = end - begin;
       begin[offset] = '\0';
        char *ip = begin;

       std:: wstring wip;
        Transcode::ANSI_to_Unicode(ip, offset, wip);
       
       wcsncpy_s( pIP, len, wip.c_str(), offset);
}

DWORD CUtility ::HttpGet(LPCTSTR lpszFullUrl, char *pBuffer, int iBufferSize)
{
        if ( lpszFullUrl == NULL )
               return 0;

        HINTERNET hNet = :: InternetOpen(_TEXT ("Mozilla/5.0 (Windows NT 6.3; WOW64; rv:33.0) Gecko/20100101 Firefox/33.0"),
               PRE_CONFIG_INTERNET_ACCESS,
               NULL,
               INTERNET_INVALID_PORT_NUMBER,
              0);
        if (hNet == NULL)
       {
               //TRACE(_T("error: InternetOpen发生异常. 错误代号: %s; 文件: %s; 行: %d/n"), ::GetLastError(), __FILE__, __LINE__);
               return 0;
       }

        HINTERNET hUrlFile = :: InternetOpenUrl(hNet,
               lpszFullUrl,
               NULL,
              0,
               INTERNET_FLAG_RELOAD,
              0);

        if (!hUrlFile)
       {
               //TRACE(_T("error:InternetOpenUrl发生异常. 错误代号: %s; 您可能需要添加\"Http://\" 或 \"Ftp://\" 文件: %s; 行: %d/n"), ::GetLastError(), __FILE__, __LINE__);
               return 0;
       }

       ::memset( pBuffer, 0, iBufferSize);
        DWORD dwBytesRead = 0;
        char szTemp[1024] = { 0 };
        DWORD dwTotalReadBytes = 0;
        while (InternetReadFile(hUrlFile, szTemp, sizeof(szTemp) - 1, &dwBytesRead))
       {
               if (0 == dwBytesRead)
                      break;
              szTemp[dwBytesRead] = 0; //此处非常重要,缺了这一句可能抓的内容就不正确

               // 缓冲区大小不够时，停止向目的缓冲区复制数据，跳出
               if (dwTotalReadBytes + dwBytesRead >= ( UINT) iBufferSize)
              {
                      pBuffer[ iBufferSize - 1] = 0;
                      break;
              }

              strcat_s( pBuffer, 1024, szTemp);
               ZeroMemory(szTemp, sizeof (szTemp));

              dwTotalReadBytes += dwBytesRead;

       }

       ::InternetCloseHandle(hUrlFile);
       ::InternetCloseHandle(hNet);
        return dwTotalReadBytes;
}