/// <summary>
/// Safely invokes the native VerifySignature function, making sure that handle ref counting is
/// performed in a proper CER.
/// </summary>
/// <param name="handle"></param>
/// <param name="qualityOfProtection"></param>
/// <param name="adapter"></param>
/// <param name="sequenceNumber"></param>
/// <returns></returns>
internal static SecurityStatus SafeVerifySignature(
SafeContextHandle handle,
int qualityOfProtection,
SecureBufferAdapter adapter,
int sequenceNumber)
{
bool gotRef = false;
SecurityStatus status = SecurityStatus.InternalError;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
handle.DangerousAddRef(ref gotRef);
}
catch (Exception)
{
if (gotRef)
{
handle.DangerousRelease();
gotRef = false;
}
throw;
}
finally
{
if (gotRef)
{
status = ContextNativeMethods.VerifySignature(
ref handle.rawHandle,
adapter.Handle,
sequenceNumber,
qualityOfProtection
);
handle.DangerousRelease();
}
}
return(status);
}
/// <summary>
/// Queries the security package's expectations regarding message/token/signature/padding buffer sizes.
/// </summary>
/// <returns></returns>
private SecPkgContext_Sizes QueryBufferSizes()
{
SecPkgContext_Sizes sizes = new SecPkgContext_Sizes();
SecurityStatus status = SecurityStatus.InternalError;
bool gotRef = false;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
this.ContextHandle.DangerousAddRef(ref gotRef);
}
catch (Exception)
{
if (gotRef)
{
this.ContextHandle.DangerousRelease();
gotRef = false;
}
throw;
}
finally
{
if (gotRef)
{
status = ContextNativeMethods.QueryContextAttributes_Sizes(
ref this.ContextHandle.rawHandle,
ContextQueryAttrib.Sizes,
ref sizes
);
this.ContextHandle.DangerousRelease();
}
}
if (status != SecurityStatus.OK)
{
throw new SspiException("Failed to query context buffer size attributes", status);
}
return(sizes);
}
/// <summary>
/// Performs and continues the authentication cycle.
/// </summary>
/// <remarks>
/// This method is performed iteratively to start, continue, and end the authentication cycle with the
/// server. Each stage works by acquiring a token from one side, presenting it to the other side
/// which in turn may generate a new token.
///
/// The cycle typically starts and ends with the client. On the first invocation on the client,
/// no server token exists, and null is provided in its place. The client returns its status, providing
/// its output token for the server. The server accepts the clients token as input and provides a
/// token as output to send back to the client. This cycle continues until the server and client
/// both indicate, typically, a SecurityStatus of 'OK'.
/// </remarks>
/// <param name="serverToken">The most recently received token from the server, or null if beginning
/// the authentication cycle.</param>
/// <param name="outToken">The clients next authentication token in the authentication cycle.</param>
/// <returns>A status message indicating the progression of the authentication cycle.
/// A status of 'OK' indicates that the cycle is complete, from the client's perspective. If the outToken
/// is not null, it must be sent to the server.
/// A status of 'Continue' indicates that the output token should be sent to the server and
/// a response should be anticipated.</returns>
public SecurityStatus Init(byte[] serverToken, out byte[] outToken)
{
TimeStamp rawExpiry = new TimeStamp();
SecurityStatus status;
SecureBuffer outTokenBuffer;
SecureBufferAdapter outAdapter;
SecureBuffer serverBuffer;
SecureBufferAdapter serverAdapter;
if (this.Disposed)
{
throw new ObjectDisposedException("ClientContext");
}
else if ((serverToken != null) && (this.ContextHandle.IsInvalid))
{
throw new InvalidOperationException("Out-of-order usage detected - have a server token, but no previous client token had been created.");
}
else if ((serverToken == null) && (this.ContextHandle.IsInvalid == false))
{
throw new InvalidOperationException("Must provide the server's response when continuing the init process.");
}
// The security package tells us how big its biggest token will be. We'll allocate a buffer
// that size, and it'll tell us how much it used.
outTokenBuffer = new SecureBuffer(
new byte[this.Credential.PackageInfo.MaxTokenLength],
BufferType.Token
);
serverBuffer = null;
if (serverToken != null)
{
serverBuffer = new SecureBuffer(serverToken, BufferType.Token);
}
// Some notes on handles and invoking InitializeSecurityContext
// - The first time around, the phContext parameter (the 'old' handle) is a null pointer to what
// would be an RawSspiHandle, to indicate this is the first time it's being called.
// The phNewContext is a pointer (reference) to an RawSspiHandle struct of where to write the
// new handle's values.
// - The next time you invoke ISC, it takes a pointer to the handle it gave you last time in phContext,
// and takes a pointer to where it should write the new handle's values in phNewContext.
// - After the first time, you can provide the same handle to both parameters. From MSDN:
// "On the second call, phNewContext can be the same as the handle specified in the phContext
// parameter."
// It will overwrite the handle you gave it with the new handle value.
// - All handle structures themselves are actually *two* pointer variables, eg, 64 bits on 32-bit
// Windows, 128 bits on 64-bit Windows.
// - So in the end, on a 64-bit machine, we're passing a 64-bit value (the pointer to the struct) that
// points to 128 bits of memory (the struct itself) for where to write the handle numbers.
using (outAdapter = new SecureBufferAdapter(outTokenBuffer))
{
if (this.ContextHandle.IsInvalid)
{
status = ContextNativeMethods.InitializeSecurityContext_1(
ref this.Credential.Handle.rawHandle,
IntPtr.Zero,
this.serverPrinc,
this.requestedAttribs,
0,
SecureBufferDataRep.Network,
IntPtr.Zero,
0,
ref this.ContextHandle.rawHandle,
outAdapter.Handle,
ref this.finalAttribs,
ref rawExpiry
);
}
else
{
using (serverAdapter = new SecureBufferAdapter(serverBuffer))
{
status = ContextNativeMethods.InitializeSecurityContext_2(
ref this.Credential.Handle.rawHandle,
ref this.ContextHandle.rawHandle,
this.serverPrinc,
this.requestedAttribs,
0,
SecureBufferDataRep.Network,
serverAdapter.Handle,
0,
ref this.ContextHandle.rawHandle,
outAdapter.Handle,
ref this.finalAttribs,
ref rawExpiry
);
}
}
}
if (status.IsError() == false)
{
if (status == SecurityStatus.OK)
{
base.Initialize(rawExpiry.ToDateTime());
}
outToken = null;
if (outTokenBuffer.Length != 0)
{
outToken = new byte[outTokenBuffer.Length];
Array.Copy(outTokenBuffer.Buffer, outToken, outToken.Length);
}
}
else
{
throw new SspiException("Failed to invoke InitializeSecurityContext for a client", status);
}
return(status);
}