How To: Set the proxy for the WebBrowser control in .NET

Source:https://blogs.msdn.microsoft.com/jpsanders/2011/04/26/how-to-set-the-proxy-for-the-webbrowser-control-in-net/

I see some horrible solutions for this out on the web.  Most involve setting the proxy for the entire machine and then toggling it back off.  Here is a class that will allow you to set it ONLY FOR THE PROCESS that the control is hosted in.  You could call it like this:

WinInetInterop.SetConnectionProxy(“localhost:8888”);

and then restore it to the default set in IE with this call:

// read the default settings for IE and restore these as the proxy
WinInetInterop.RestoreSystemProxy();
Let me know if you thought this was useful!

Listing:

Using System;
using System.Runtime.InteropServices;

namespace SetProxy
{
public static class WinInetInterop
{
public static string applicationName;

[DllImport(“wininet.dll”, SetLastError = true, CharSet = CharSet.Auto)]
private static extern IntPtr InternetOpen(
string lpszAgent, int dwAccessType, string lpszProxyName,
string lpszProxyBypass, int dwFlags);

[DllImport(“wininet.dll”, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool InternetCloseHandle(IntPtr hInternet);

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
private struct INTERNET_PER_CONN_OPTION_LIST
{
public int Size;

// The connection to be set. NULL means LAN.
public System.IntPtr Connection;

public int OptionCount;
public int OptionError;

// List of INTERNET_PER_CONN_OPTIONs.
public System.IntPtr pOptions;
}
private enum INTERNET_OPTION
{
// Sets or retrieves an INTERNET_PER_CONN_OPTION_LIST structure that specifies
// a list of options for a particular connection.
INTERNET_OPTION_PER_CONNECTION_OPTION = 75,

// Notify the system that the registry settings have been changed so that
// it verifies the settings on the next call to InternetConnect.
INTERNET_OPTION_SETTINGS_CHANGED = 39,

// Causes the proxy data to be reread from the registry for a handle.
INTERNET_OPTION_REFRESH = 37

}

private enum INTERNET_PER_CONN_OptionEnum
{
INTERNET_PER_CONN_FLAGS = 1,
INTERNET_PER_CONN_PROXY_SERVER = 2,
INTERNET_PER_CONN_PROXY_BYPASS = 3,
INTERNET_PER_CONN_AUTOCONFIG_URL = 4,
INTERNET_PER_CONN_AUTODISCOVERY_FLAGS = 5,
INTERNET_PER_CONN_AUTOCONFIG_SECONDARY_URL = 6,
INTERNET_PER_CONN_AUTOCONFIG_RELOAD_DELAY_MINS = 7,
INTERNET_PER_CONN_AUTOCONFIG_LAST_DETECT_TIME = 8,
INTERNET_PER_CONN_AUTOCONFIG_LAST_DETECT_URL = 9,
INTERNET_PER_CONN_FLAGS_UI = 10
}
private const int INTERNET_OPEN_TYPE_DIRECT = 1;  // direct to net
private const int INTERNET_OPEN_TYPE_PRECONFIG = 0; // read registry
/// <summary>
/// Constants used in INTERNET_PER_CONN_OPTON struct.
/// </summary>
private enum INTERNET_OPTION_PER_CONN_FLAGS
{
PROXY_TYPE_DIRECT = 0x00000001,   // direct to net
PROXY_TYPE_PROXY = 0x00000002,   // via named proxy
PROXY_TYPE_AUTO_PROXY_URL = 0x00000004,   // autoproxy URL
PROXY_TYPE_AUTO_DETECT = 0x00000008   // use autoproxy detection
}

/// <summary>
/// Used in INTERNET_PER_CONN_OPTION.
/// When create a instance of OptionUnion, only one filed will be used.
/// The StructLayout and FieldOffset attributes could help to decrease the struct size.
/// </summary>
[StructLayout(LayoutKind.Explicit)]
private struct INTERNET_PER_CONN_OPTION_OptionUnion
{
// A value in INTERNET_OPTION_PER_CONN_FLAGS.
[FieldOffset(0)]
public int dwValue;
[FieldOffset(0)]
public System.IntPtr pszValue;
[FieldOffset(0)]
public System.Runtime.InteropServices.ComTypes.FILETIME ftValue;
}

[StructLayout(LayoutKind.Sequential)]
private struct INTERNET_PER_CONN_OPTION
{
// A value in INTERNET_PER_CONN_OptionEnum.
public int dwOption;
public INTERNET_PER_CONN_OPTION_OptionUnion Value;
}
/// <summary>
/// Sets an Internet option.
/// </summary>
[DllImport(“wininet.dll”, CharSet = CharSet.Ansi, SetLastError = true)]
private static extern bool InternetSetOption(
IntPtr hInternet,
INTERNET_OPTION dwOption,
IntPtr lpBuffer,
int lpdwBufferLength);

/// <summary>
/// Queries an Internet option on the specified handle. The Handle will be always 0.
/// </summary>
[DllImport(“wininet.dll”, CharSet = CharSet.Ansi, SetLastError = true,
EntryPoint = “InternetQueryOption”)]
private extern static bool InternetQueryOptionList(
IntPtr Handle,
INTERNET_OPTION OptionFlag,
ref INTERNET_PER_CONN_OPTION_LIST OptionList,
ref int size);

/// <summary>
/// Set the proxy server for LAN connection.
/// </summary>
public static bool SetConnectionProxy(string proxyServer )
{

IntPtr hInternet = InternetOpen(applicationName,INTERNET_OPEN_TYPE_DIRECT, null, null, 0);

//// Create 3 options.
//INTERNET_PER_CONN_OPTION[] Options = new INTERNET_PER_CONN_OPTION[3];

// Create 2 options.
INTERNET_PER_CONN_OPTION[] Options = new INTERNET_PER_CONN_OPTION[2];

// Set PROXY flags.
Options[0] = new INTERNET_PER_CONN_OPTION();
Options[0].dwOption = (int)INTERNET_PER_CONN_OptionEnum.INTERNET_PER_CONN_FLAGS;
Options[0].Value.dwValue = (int)INTERNET_OPTION_PER_CONN_FLAGS.PROXY_TYPE_PROXY;

// Set proxy name.
Options[1] = new INTERNET_PER_CONN_OPTION();
Options[1].dwOption =
(int)INTERNET_PER_CONN_OptionEnum.INTERNET_PER_CONN_PROXY_SERVER;
Options[1].Value.pszValue = Marshal.StringToHGlobalAnsi(proxyServer);

//// Set proxy bypass.
//Options[2] = new INTERNET_PER_CONN_OPTION();
//Options[2].dwOption =
//    (int)INTERNET_PER_CONN_OptionEnum.INTERNET_PER_CONN_PROXY_BYPASS;
//Options[2].Value.pszValue = Marshal.StringToHGlobalAnsi(“local”);

//// Allocate a block of memory of the options.
//System.IntPtr buffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(Options[0])
//    + Marshal.SizeOf(Options[1]) + Marshal.SizeOf(Options[2]));

// Allocate a block of memory of the options.
System.IntPtr buffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(Options[0])
+ Marshal.SizeOf(Options[1]));

System.IntPtr current = buffer;

// Marshal data from a managed object to an unmanaged block of memory.
for (int i = 0; i < Options.Length; i++)
{
Marshal.StructureToPtr(Options[i], current, false);
current = (System.IntPtr)((int)current + Marshal.SizeOf(Options[i]));
}

// Initialize a INTERNET_PER_CONN_OPTION_LIST instance.
INTERNET_PER_CONN_OPTION_LIST option_list = new INTERNET_PER_CONN_OPTION_LIST();

// Point to the allocated memory.
option_list.pOptions = buffer;

// Return the unmanaged size of an object in bytes.
option_list.Size = Marshal.SizeOf(option_list);

// IntPtr.Zero means LAN connection.
option_list.Connection = IntPtr.Zero;

option_list.OptionCount = Options.Length;
option_list.OptionError = 0;
int size = Marshal.SizeOf(option_list);

// Allocate memory for the INTERNET_PER_CONN_OPTION_LIST instance.
IntPtr intptrStruct = Marshal.AllocCoTaskMem(size);

// Marshal data from a managed object to an unmanaged block of memory.
Marshal.StructureToPtr(option_list, intptrStruct, true);

// Set internet settings.
bool bReturn = InternetSetOption(hInternet,
INTERNET_OPTION.INTERNET_OPTION_PER_CONNECTION_OPTION, intptrStruct, size);

// Free the allocated memory.
Marshal.FreeCoTaskMem(buffer);
Marshal.FreeCoTaskMem(intptrStruct);
InternetCloseHandle(hInternet);

// Throw an exception if this operation failed.
if (!bReturn)
{
throw new ApplicationException(” Set Internet Option Failed!”);
}

return bReturn;
}

 

/// <summary>
/// Backup the current options for LAN connection.
/// Make sure free the memory after restoration.
/// </summary>
private static INTERNET_PER_CONN_OPTION_LIST GetSystemProxy()
{

// Query following options.
INTERNET_PER_CONN_OPTION[] Options = new INTERNET_PER_CONN_OPTION[3];

Options[0] = new INTERNET_PER_CONN_OPTION();
Options[0].dwOption = (int)INTERNET_PER_CONN_OptionEnum.INTERNET_PER_CONN_FLAGS;
Options[1] = new INTERNET_PER_CONN_OPTION();
Options[1].dwOption = (int)INTERNET_PER_CONN_OptionEnum.INTERNET_PER_CONN_PROXY_SERVER;
Options[2] = new INTERNET_PER_CONN_OPTION();
Options[2].dwOption = (int)INTERNET_PER_CONN_OptionEnum.INTERNET_PER_CONN_PROXY_BYPASS;

// Allocate a block of memory of the options.
System.IntPtr buffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(Options[0])
+ Marshal.SizeOf(Options[1]) + Marshal.SizeOf(Options[2]));

System.IntPtr current = (System.IntPtr)buffer;

// Marshal data from a managed object to an unmanaged block of memory.
for (int i = 0; i < Options.Length; i++)
{
Marshal.StructureToPtr(Options[i], current, false);
current = (System.IntPtr)((int)current + Marshal.SizeOf(Options[i]));
}

// Initialize a INTERNET_PER_CONN_OPTION_LIST instance.
INTERNET_PER_CONN_OPTION_LIST Request = new INTERNET_PER_CONN_OPTION_LIST();

// Point to the allocated memory.
Request.pOptions = buffer;

Request.Size = Marshal.SizeOf(Request);

// IntPtr.Zero means LAN connection.
Request.Connection = IntPtr.Zero;

Request.OptionCount = Options.Length;
Request.OptionError = 0;
int size = Marshal.SizeOf(Request);

// Query internet options.
bool result = InternetQueryOptionList(IntPtr.Zero,
INTERNET_OPTION.INTERNET_OPTION_PER_CONNECTION_OPTION,
ref Request, ref size);
if (!result)
{
throw new ApplicationException(” Set Internet Option Failed! “);
}

return Request;
}

/// <summary>
/// Restore the options for LAN connection.
/// </summary>
/// <param name=”request”></param>
/// <returns></returns>
public static bool RestoreSystemProxy()
{

IntPtr hInternet = InternetOpen(applicationName, INTERNET_OPEN_TYPE_DIRECT, null, null, 0);

INTERNET_PER_CONN_OPTION_LIST request = GetSystemProxy();
int size = Marshal.SizeOf(request);

// Allocate memory.
IntPtr intptrStruct = Marshal.AllocCoTaskMem(size);

// Convert structure to IntPtr
Marshal.StructureToPtr(request, intptrStruct, true);

// Set internet options.
bool bReturn = InternetSetOption(hInternet,
INTERNET_OPTION.INTERNET_OPTION_PER_CONNECTION_OPTION,
intptrStruct, size);

// Free the allocated memory.
Marshal.FreeCoTaskMem(request.pOptions);
Marshal.FreeCoTaskMem(intptrStruct);

if (!bReturn)
{
throw new ApplicationException(” Set Internet Option Failed! “);
}

// Notify the system that the registry settings have been changed and cause
// the proxy data to be reread from the registry for a handle.
InternetSetOption(hInternet, INTERNET_OPTION.INTERNET_OPTION_SETTINGS_CHANGED,
IntPtr.Zero, 0);
InternetSetOption(hInternet, INTERNET_OPTION.INTERNET_OPTION_REFRESH,
IntPtr.Zero, 0);

InternetCloseHandle(hInternet);

return bReturn;
}

}
}

发表评论