You've already forked linux-packaging-mono
346 lines
15 KiB
C#
346 lines
15 KiB
C#
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using System.Text;
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using System.Collections.Generic;
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using System.Runtime.InteropServices;
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using Microsoft.Win32;
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using System.Runtime.CompilerServices;
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using System.Net.Configuration;
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namespace System.Net
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{
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// This class uses WinHttp APIs only to find, download and execute the PAC file.
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internal sealed class WinHttpWebProxyFinder : BaseWebProxyFinder
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{
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private SafeInternetHandle session;
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private bool autoDetectFailed;
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public WinHttpWebProxyFinder(AutoWebProxyScriptEngine engine)
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: base(engine)
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{
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// Don't specify a user agent and dont' specify proxy settings. This is the same behavior WinHttp
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// uses when downloading the PAC file.
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session = UnsafeNclNativeMethods.WinHttp.WinHttpOpen(null,
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UnsafeNclNativeMethods.WinHttp.AccessType.NoProxy, null, null, 0);
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// Don't throw on error, just log the error information. This is consistent with how auto-proxy
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// works: we never throw on error (discovery, download, execution errors).
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if (session == null || session.IsInvalid)
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{
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int errorCode = GetLastWin32Error();
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if (Logging.On) Logging.PrintError(Logging.Web, SR.GetString(SR.net_log_proxy_winhttp_cant_open_session, errorCode));
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}
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else
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{
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// The default download-timeout is 1 min.
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// WinHTTP will use the sum of all four timeouts provided in WinHttpSetTimeouts as the
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// actual timeout. Setting a value to 0 means "infinite".
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// Since we don't provide the ability to specify finegrained timeouts like WinHttp does,
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// we simply apply the configured timeout to all four WinHttp timeouts.
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int timeout = SettingsSectionInternal.Section.DownloadTimeout;
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if (!UnsafeNclNativeMethods.WinHttp.WinHttpSetTimeouts(session, timeout, timeout, timeout, timeout))
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{
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// We weren't able to set the timeouts. Just log and continue.
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int errorCode = GetLastWin32Error();
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if (Logging.On) Logging.PrintError(Logging.Web, SR.GetString(SR.net_log_proxy_winhttp_timeout_error, errorCode));
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}
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}
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}
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public override bool GetProxies(Uri destination, out IList<string> proxyList)
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{
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proxyList = null;
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if (session == null || session.IsInvalid)
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{
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return false;
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}
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if (State == AutoWebProxyState.UnrecognizedScheme)
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{
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// If a previous call already determined that we don't support the scheme of the script
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// location, then just return false.
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return false;
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}
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string proxyListString = null;
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// Set to auto-detect failed. In case auto-detect is turned off and a script-location is available
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// we'll try downloading the script from that location.
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int errorCode = (int)UnsafeNclNativeMethods.WinHttp.ErrorCodes.AudodetectionFailed;
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// If auto-detect is turned on, try to execute DHCP/DNS query to get PAC file, then run the script
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if (Engine.AutomaticallyDetectSettings && !autoDetectFailed)
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{
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errorCode = GetProxies(destination, null, out proxyListString);
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// Remember if auto-detect failed. If config-script works, then the next time GetProxies() is
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// called, we'll not try auto-detect but jump right to config-script.
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autoDetectFailed = IsErrorFatalForAutoDetect(errorCode);
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if (errorCode == (int)UnsafeNclNativeMethods.WinHttp.ErrorCodes.UnrecognizedScheme)
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{
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// DHCP returned FILE or FTP scheme for the PAC file location: We should stop here
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// since this is not an error, but a feature WinHttp doesn't currently support. The
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// caller may be able to handle this case by using another WebProxyFinder.
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State = AutoWebProxyState.UnrecognizedScheme;
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return false;
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}
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}
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// If auto-detect failed or was turned off, and a config-script location is available, download
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// the script from that location and execute it.
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if ((Engine.AutomaticConfigurationScript != null) && (IsRecoverableAutoProxyError(errorCode)))
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{
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errorCode = GetProxies(destination, Engine.AutomaticConfigurationScript,
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out proxyListString);
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}
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State = GetStateFromErrorCode(errorCode);
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if (State == AutoWebProxyState.Completed)
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{
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if (string.IsNullOrEmpty(proxyListString))
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{
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// In this case the PAC file execution returned "DIRECT", i.e. WinHttp returned
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// 'true' with a 'null' proxy string. This state is represented as a list
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// containing one element with value 'null'.
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proxyList = new string[1] { null };
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}
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else
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{
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// WinHttp doesn't really clear all whitespaces. It does a pretty good job with
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// spaces, but e.g. tabs aren't removed. Therefore make sure all whitespaces get
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// removed.
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// Note: Even though the PAC script could use space characters as separators,
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// WinHttp will always use ';' as separator character. E.g. for the PAC result
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// "PROXY 192.168.0.1 PROXY 192.168.0.2" WinHttp will return "192.168.0.1;192.168.0.2".
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// WinHttp will also remove trailing ';'.
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proxyListString = RemoveWhitespaces(proxyListString);
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proxyList = proxyListString.Split(';');
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}
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return true;
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}
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// We get here if something went wrong, or if neither auto-detect nor script-location
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// were turned on.
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return false;
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}
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public override void Abort()
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{
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// WinHttp doesn't support aborts. Therefore we can't do anything here.
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}
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public override void Reset()
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{
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base.Reset();
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// Reset auto-detect failure: If the connection changes, we may be able to do auto-detect again.
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autoDetectFailed = false;
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}
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protected override void Dispose(bool disposing)
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{
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if (disposing)
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{
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if (session != null && !session.IsInvalid)
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{
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session.Close();
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}
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}
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}
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private int GetProxies(Uri destination, Uri scriptLocation, out string proxyListString)
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{
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int errorCode = 0;
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proxyListString = null;
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UnsafeNclNativeMethods.WinHttp.WINHTTP_AUTOPROXY_OPTIONS autoProxyOptions =
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new UnsafeNclNativeMethods.WinHttp.WINHTTP_AUTOPROXY_OPTIONS();
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// Always try to download the PAC file without authentication. If we turn auth. on, the WinHttp
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// service will create a new session for every request (performance/memory implications).
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// Therefore we only turn auto-logon on if it is really needed.
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autoProxyOptions.AutoLogonIfChallenged = false;
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if (scriptLocation == null)
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{
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// Use auto-discovery to find the script location.
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autoProxyOptions.Flags = UnsafeNclNativeMethods.WinHttp.AutoProxyFlags.AutoDetect;
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autoProxyOptions.AutoConfigUrl = null;
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autoProxyOptions.AutoDetectFlags = UnsafeNclNativeMethods.WinHttp.AutoDetectType.Dhcp |
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UnsafeNclNativeMethods.WinHttp.AutoDetectType.DnsA;
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}
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else
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{
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// Use the provided script location for the PAC file.
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autoProxyOptions.Flags = UnsafeNclNativeMethods.WinHttp.AutoProxyFlags.AutoProxyConfigUrl;
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autoProxyOptions.AutoConfigUrl = scriptLocation.ToString();
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autoProxyOptions.AutoDetectFlags = UnsafeNclNativeMethods.WinHttp.AutoDetectType.None;
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}
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if (!WinHttpGetProxyForUrl(destination.ToString(), ref autoProxyOptions, out proxyListString))
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{
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errorCode = GetLastWin32Error();
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// If the PAC file can't be downloaded because auth. was required, we check if the
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// credentials are set; if so, then we try again using auto-logon.
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// Note that by default webProxy.Credentials will be null. The user needs to set
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// <defaultProxy useDefaultCredentials="true"> in the config file, in order for
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// webProxy.Credentials to be set to DefaultNetworkCredentials.
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if ((errorCode == (int)UnsafeNclNativeMethods.WinHttp.ErrorCodes.LoginFailure) &&
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(Engine.Credentials != null))
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{
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// Now we need to try again, this time by enabling auto-logon.
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autoProxyOptions.AutoLogonIfChallenged = true;
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if (!WinHttpGetProxyForUrl(destination.ToString(), ref autoProxyOptions,
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out proxyListString))
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{
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errorCode = GetLastWin32Error();
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}
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}
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if (Logging.On) Logging.PrintError(Logging.Web, SR.GetString(SR.net_log_proxy_winhttp_getproxy_failed, destination, errorCode));
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}
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return errorCode;
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}
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private bool WinHttpGetProxyForUrl(string destination,
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ref UnsafeNclNativeMethods.WinHttp.WINHTTP_AUTOPROXY_OPTIONS autoProxyOptions,
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out string proxyListString)
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{
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proxyListString = null;
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bool success = false;
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UnsafeNclNativeMethods.WinHttp.WINHTTP_PROXY_INFO proxyInfo =
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new UnsafeNclNativeMethods.WinHttp.WINHTTP_PROXY_INFO();
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// Make sure the strings get cleaned up in a CER (thus unexpected exceptions, like
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// ThreadAbortException will not interrupt the execution of the finally block, and we'll not
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// leak resources).
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RuntimeHelpers.PrepareConstrainedRegions();
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try
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{
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success = UnsafeNclNativeMethods.WinHttp.WinHttpGetProxyForUrl(session,
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destination, ref autoProxyOptions, out proxyInfo);
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if (success)
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{
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proxyListString = Marshal.PtrToStringUni(proxyInfo.Proxy);
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}
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}
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finally
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{
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Marshal.FreeHGlobal(proxyInfo.Proxy);
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Marshal.FreeHGlobal(proxyInfo.ProxyBypass);
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}
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return success;
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}
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private static int GetLastWin32Error()
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{
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int errorCode = Marshal.GetLastWin32Error();
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if (errorCode == NativeMethods.ERROR_NOT_ENOUGH_MEMORY)
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{
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throw new OutOfMemoryException();
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}
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return errorCode;
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}
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private static bool IsRecoverableAutoProxyError(int errorCode)
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{
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GlobalLog.Assert(errorCode != UnsafeNclNativeMethods.ErrorCodes.ERROR_INVALID_PARAMETER,
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"WinHttpGetProxyForUrl() call: Error code 'Invalid parameter' should not be returned.");
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// According to WinHttp the following states can be considered "recoverable", i.e.
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// we should continue trying WinHttpGetProxyForUrl() with the provided script-location
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// (if available).
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switch ((UnsafeNclNativeMethods.WinHttp.ErrorCodes)errorCode)
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{
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.AutoProxyServiceError:
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.AudodetectionFailed:
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.BadAutoProxyScript:
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.LoginFailure:
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.OperationCancelled:
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.Timeout:
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.UnableToDownloadScript:
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.UnrecognizedScheme:
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return true;
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}
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return false;
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}
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private static AutoWebProxyState GetStateFromErrorCode(int errorCode)
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{
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if (errorCode == UnsafeNclNativeMethods.ErrorCodes.ERROR_SUCCESS)
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{
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return AutoWebProxyState.Completed;
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}
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switch ((UnsafeNclNativeMethods.WinHttp.ErrorCodes)errorCode)
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{
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.AudodetectionFailed:
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return AutoWebProxyState.DiscoveryFailure;
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.UnableToDownloadScript:
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return AutoWebProxyState.DownloadFailure;
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.UnrecognizedScheme:
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return AutoWebProxyState.UnrecognizedScheme;
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.BadAutoProxyScript:
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.InvalidUrl:
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.AutoProxyServiceError:
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// AutoProxy succeeded, but no proxy could be found for this request
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return AutoWebProxyState.Completed;
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default:
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// We don't know the exact cause of the failure. Set the state to compilation failure to
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// indicate that something went wrong.
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return AutoWebProxyState.CompilationFailure;
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}
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}
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private static string RemoveWhitespaces(string value)
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{
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StringBuilder result = new StringBuilder();
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foreach (char c in value)
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{
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if (!char.IsWhiteSpace(c))
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{
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result.Append(c);
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}
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}
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return result.ToString();
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}
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// Should we ignore auto-detect from now on?
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// http://msdn.microsoft.com/en-us/library/aa384097(VS.85).aspx
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private static bool IsErrorFatalForAutoDetect(int errorCode)
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{
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switch ((UnsafeNclNativeMethods.WinHttp.ErrorCodes)errorCode)
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{
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.Success:
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.InvalidUrl:
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// Some URIs are not supported (like Unicode hosts on Win7 and lower),
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// but our proxy is still valid
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.BadAutoProxyScript:
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// Got the script, but something went wrong in execution. For example,
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// the request was for an unresolvable single label name.
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case UnsafeNclNativeMethods.WinHttp.ErrorCodes.AutoProxyServiceError:
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// Returned when a proxy for the specified URL cannot be located.
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return false;
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default:
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return true;
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}
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}
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}
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}
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