侦测IE的代理服务器

http://blog.csdn.net/cnjet/article/details/8284127

所有的网络程序使用HTTP服务时，必然会遇到可能需要检测代理服务器的情况，程序可以提供界面供玩家设置，但是更常用的一种方式是自动检测IE浏览器的代理设置，并以此为代理来设置应用程序的代理信息，Opera, Firefox, Chrome等主流浏览器都是如此。以下程序使用WinHTTP的API实现自动的代理检测，支持“自动检测”，“自动检测代理文件”，“手动设置”，无代理等各种情况。

源代码

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int GetHTTPProxyFromIE(const WCHAR* url, /*out*/std::wstring &server )
{
BOOL auto_proxy = FALSE;
WINHTTP_AUTOPROXY_OPTIONS auto_proxy_option;
WINHTTP_PROXY_INFO auto_proxy_info;

ZeroMemory( &auto_proxy_option, sizeof(WINHTTP_AUTOPROXY_OPTIONS) );
ZeroMemory( &auto_proxy_info, sizeof(WINHTTP_PROXY_INFO) );

//
// convert URL from mbs to wchar
//
const WCHAR* url_request = L"http://www.youtube.com";
if( NULL!=url && wcslen(url)>0 )
url_request = url;

server = L"";

//
// Create the WinHTTP session.
//
HINTERNET http_session = WinHttpOpen( L"ProxyDetect/1.0",
WINHTTP_ACCESS_TYPE_NO_PROXY,
WINHTTP_NO_PROXY_NAME,
WINHTTP_NO_PROXY_BYPASS,
0 );

if( NULL==http_session ) {
return -2;
}

if (!WinHttpSetTimeouts( http_session, 30000, 30000, 0, 0)) {
printf( "Error %u in WinHttpSetTimeouts.\n", GetLastError());

WinHttpCloseHandle(http_session);
return -3;
}

//
// Check if need auto proxy.
//
WINHTTP_CURRENT_USER_IE_PROXY_CONFIG ie_config;
if( WinHttpGetIEProxyConfigForCurrentUser(&ie_config) ) {
if( ie_config.fAutoDetect )
auto_proxy = TRUE;

if( NULL!=ie_config.lpszAutoConfigUrl ) {
auto_proxy = TRUE;
auto_proxy_option.lpszAutoConfigUrl = ie_config.lpszAutoConfigUrl;
}
} else {
// Error, Try to auto proxy.
auto_proxy = TRUE;
}

//
// request auto detect to get proxy info.
//
if( auto_proxy ) {
// Setting auto detect options
if( NULL!=auto_proxy_option.lpszAutoConfigUrl ) {
auto_proxy_option.dwFlags = WINHTTP_AUTOPROXY_CONFIG_URL;
} else {
auto_proxy_option.dwFlags = WINHTTP_AUTOPROXY_AUTO_DETECT;
auto_proxy_option.dwAutoDetectFlags = WINHTTP_AUTO_DETECT_TYPE_DHCP|WINHTTP_AUTO_DETECT_TYPE_DNS_A;
}

// basic flags you almost always want
auto_proxy_option.fAutoLogonIfChallenged = TRUE;

// here we reset fAutoProxy in case an auto-proxy isn‘t actually
// configured for this URL
auto_proxy = WinHttpGetProxyForUrl(http_session, url_request, &auto_proxy_option, &auto_proxy_info );
}

//
// Output result
//
if( auto_proxy ) {
// set proxy options based on auto proxy info.
server = auto_proxy_info.lpszProxy;
} else if( NULL!=ie_config.lpszProxy ) {
// IE has an explicit proxy. set proxy options for libcurl here
// based on ieProxyConfig
//
// note that sometimes IE gives just a single or double colon
// for proxy or bypass list, which means "no proxy"
server = ie_config.lpszProxy;
} else {
// there is no auto proxy and no manually configured proxy
}

//
// Clean up.
//
if( ie_config.lpszAutoConfigUrl != NULL )
GlobalFree(ie_config.lpszAutoConfigUrl);

if( auto_proxy_info.lpszProxy != NULL )
GlobalFree(auto_proxy_info.lpszProxy);

if( auto_proxy_info.lpszProxyBypass != NULL )
GlobalFree( auto_proxy_info.lpszProxyBypass );

if( http_session != NULL )
WinHttpCloseHandle( http_session );

return 0;
}

参考信息：

http://curl.haxx.se/mail/lib-2001-08/att-0170/winproxy.c

http://stackoverflow.com/questions/202547/how-do-i-find-out-the-browsers-proxy-settings