这是设置。在 ASP.Net 站点上，我们希望在特定页面上进行 NTLM 身份验证。这样做的方式是有一个模块只响应这些页面，然后执行 NTLM 身份验证所需的来回请求/响应。
NTLM 并不是那么容易，所以经过一番挖掘，我发现 Cassini 实际上内置了这个功能：
http://cassinidev.codeplex.com/SourceControl/changeset/view/70631#1365123
这是相关的方法：
public unsafe bool Authenticate(string blobString)
{
_blob = null;
byte[] buffer = Convert.FromBase64String(blobString);
byte[] inArray = new byte[0x4000];
fixed (void* ptrRef = &_securityContext)
{
fixed (void* ptrRef2 = &_inputBuffer)
{
fixed (void* ptrRef3 = &_outputBuffer)
{
fixed (void* ptrRef4 = buffer)
{
fixed (void* ptrRef5 = inArray)
{
IntPtr zero = IntPtr.Zero;
if (_securityContextAcquired)
{
zero = (IntPtr) ptrRef;
}
_inputBufferDesc.ulVersion = 0;
_inputBufferDesc.cBuffers = 1;
_inputBufferDesc.pBuffers = (IntPtr) ptrRef2;
_inputBuffer.cbBuffer = (uint) buffer.Length;
_inputBuffer.BufferType = 2;
_inputBuffer.pvBuffer = (IntPtr) ptrRef4;
_outputBufferDesc.ulVersion = 0;
_outputBufferDesc.cBuffers = 1;
_outputBufferDesc.pBuffers = (IntPtr) ptrRef3;
_outputBuffer.cbBuffer = (uint) inArray.Length;
_outputBuffer.BufferType = 2;
_outputBuffer.pvBuffer = (IntPtr) ptrRef5;
int num = Interop.AcceptSecurityContext(ref _credentialsHandle, zero,
ref _inputBufferDesc, 20,
0, ref _securityContext, ref _outputBufferDesc,
ref _securityContextAttributes, ref _timestamp);
if (num == 0x90312)
{
_securityContextAcquired = true;
_blob = Convert.ToBase64String(inArray, 0, (int) _outputBuffer.cbBuffer);
}
else
{
if (num != 0)
{
return false;
}
IntPtr phToken = IntPtr.Zero;
if (Interop.QuerySecurityContextToken(ref _securityContext, ref phToken) != 0)
{
return false;
}
try
{
using (WindowsIdentity identity = new WindowsIdentity(phToken))
{
_sid = identity.User;
}
}
finally
{
Interop.CloseHandle(phToken);
}
_completed = true;
}
}
}
}
}
}
return true;
}
以下是 Cassini 使用该代码的方式：
http://cassinidev.codeplex.com/SourceControl/changeset/view/70631#1365119
private bool TryNtlmAuthenticate()
{
try
{
using (var auth = new NtlmAuth())
{
do
{
string blobString = null;
string extraHeaders = _knownRequestHeaders[0x18];
if ((extraHeaders != null) && extraHeaders.StartsWith("NTLM ", StringComparison.Ordinal))
{
blobString = extraHeaders.Substring(5);
}
if (blobString != null)
{
if (!auth.Authenticate(blobString))
{
_connection.WriteErrorAndClose(0x193);
return false;
}
if (auth.Completed)
{
goto Label_009A;
}
extraHeaders = "WWW-Authenticate: NTLM " + auth.Blob + "\r\n";
}
else
{
extraHeaders = "WWW-Authenticate: NTLM\r\n";
}
SkipAllPostedContent();
_connection.WriteErrorWithExtraHeadersAndKeepAlive(0x191, extraHeaders);
} while (TryParseRequest());
return false;
Label_009A:
if (_host.GetProcessSid() != auth.SID)
{
_connection.WriteErrorAndClose(0x193);
return false;
}
}
}
catch
{
try
{
_connection.WriteErrorAndClose(500);
}
// ReSharper disable EmptyGeneralCatchClause
catch
// ReSharper restore EmptyGeneralCatchClause
{
}
return false;
}
return true;
}
这是基本的工作流程。第一次，它只是将“WWW-Authenticate: NTLM”添加到标题中。客户端响应 NTLM: some token string。此时，Cassini 获取此字符串，并使用它来调用底层的 AcceptSecurityContext WinAPI 调用。这会生成另一个令牌字符串，然后将其发送回客户端。然后客户端发回另一个加密的令牌字符串，然后 Cassini 再次将其传递给 AcceptSecurityContext 方法。此时在 Cassini 应用程序中，身份验证成功，我们都很好。
我曾尝试在我的模块中重现此内容，但由于某种原因，在最后一次握手时，我无法进行身份验证：
public class TestModule : IHttpModule
{
public void Dispose()
{
}
public void Init(HttpApplication context)
{
context.BeginRequest += new EventHandler(context_BeginRequest);
}
void context_BeginRequest(object sender, EventArgs e)
{
var context = HttpContext.Current;
var headers = context.Request.Headers;
if (String.IsNullOrEmpty(headers.Get("Authorization")))
{
context.Response.StatusCode = 401;
context.Response.AddHeader("WWW-Authenticate", "NTLM");
}
else
{
Step2(context);
}
}
private void Step2(HttpContext httpContext)
{
using (var auth = new NtlmAuth())
{
var header = httpContext.Request.Headers["Authorization"].Substring(5);
var result = auth.Authenticate(header); //third time around, this returns false. AcceptSecurityContext in NtmlAuth fails....
if (!result)
{
ReturnUnauthorized(httpContext);
}
else if (!auth.Completed)
{
HttpContext.Current.Response.Charset = null;
HttpContext.Current.Response.ContentType = null;
httpContext.Response.StatusCode = 401;
httpContext.Response.AddHeader("WWW-Authenticate", "NTLM " + auth.Blob);
httpContext.Response.End();
}
else
{
httpContext.Response.StatusCode = 200;
httpContext.Response.Write("Yay!");
httpContext.Response.End();
}
}
}
private void ReturnUnauthorized(HttpContext httpContext)
{
httpContext.Response.StatusCode = 403;
httpContext.Response.End();
}
}
每次调用它时，我都会收到以下响应：“SEC_E_INVALID_TOKEN”，根据文档，这意味着：“函数失败。传递给函数的令牌无效。”。我的测试站点在 IIS 中运行，此时此模块针对所有请求运行。我在标头中设置了 Keep-Alive（NTLM 在最后两个响应/请求期间需要相同的连接）。
我尝试过的其他事情：使用 Fiddler，我查看了从 Cassini 发回的标头，并尝试让我的模块发回相同的标头。没运气。我尝试更改站点运行的用户，但这也无济于事。
基本上，我的问题是，为什么它一直失败？为什么 Cassini 可以成功验证，而我的网站却不能？