////////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   Services/CredentialsManager/Ntlm.sg
//
//  Note:	Contains the code that allows the Credentials Manager to use NTLM.
//			The NTLM algorithms are not implemented in this file; they're in 
//			the Libraries/Ntlm.
//

using System;
using System.Collections;
using System.Diagnostics;
using System.Threading;
using Microsoft.Contracts;
using Microsoft.Singularity;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.Io;
using Microsoft.SingSharp;
using NtlmSupplicant = System.Security.Protocols.Ntlm.NtlmSupplicant;

using Ex = Microsoft.Singularity.Security;

namespace Microsoft.Singularity.Security.CredentialsManager
{
    class NtlmAuthenticationProtocol : AuthenticationProtocol
    {
        public override bool CreateSupplicant([Claims]ServiceContract.Exp! exp, Credentials! credentials, out CredError error)
        {
            // The only kind of evidence that NTLM supports is PasswordEvidence.
            PasswordEvidence pwevidence = credentials.Evidence as PasswordEvidence;
            if (pwevidence == null) {
                delete exp;
                error = CredError.EvidenceTypeNotSupported;
                return false;
            }
            
            // Parse the username and domain name from the credentials name.
            
            string! credentialsName = credentials.Id.CredentialsName;
            string! username;
            string! domain;
            
            int separator = credentialsName.IndexOf('\\');
            if (separator != -1) {
                // Is it "domain\user"?
                username = credentialsName.Substring(separator + 1);
                domain = credentialsName.Substring(0, separator);
            }
            else {
                separator = credentialsName.IndexOf('@');
                if (separator != -1) {
                    // Is it "user@domain.foo"?
                    username = credentialsName.Substring(0, separator);
                    domain = credentialsName.Substring(separator + 1);
                }
                else {
                    // No, and no.  Assume "user", and use a domain of ".", which most implementations
                    // interpret as meaning "this machine" or "this domain".
                    username = credentialsName;
                    domain = ".";
                }
            }
            
            // Which contract does the client want to use?
            
            NtlmSupplicantContract.Exp ntlm_exp = exp as NtlmSupplicantContract.Exp;
            GssSupplicantContract.Exp gss_exp;
            
            if ((ntlm_exp = exp as NtlmSupplicantContract.Exp) != null) {
                NtlmLegacySupplicantClient.StartServiceThread(ntlm_exp, pwevidence);
                error = CredError.NoError;
                return true;
            }
            else if ((gss_exp = exp as GssSupplicantContract.Exp) != null) {
                NtlmGssSupplicantClient.StartServiceThread(gss_exp, username, domain, pwevidence);
                error = CredError.NoError;
                return true;
            }
            else {
                delete exp;
                error = CredError.ContractNotSupported;
                return false;
            }
            
        }
    }
    
    ///
    //<summary>
    //  This class provides raw access to the NTLM supplicant, using NtlmSupplicantContract.
    //  This is for clients that deal directly with the username, domain name, the NTLM
    //  challenge, and response, all as discrete fields.
    //</summary>
    //
    class NtlmLegacySupplicantClient
    {
        public static void StartServiceThread([Claims]NtlmSupplicantContract.Exp:Start! exp, PasswordEvidence! evidence)
        {
            NtlmLegacySupplicantClient client = new NtlmLegacySupplicantClient(exp, evidence);
            ThreadStart start = new ThreadStart(client.ThreadServiceRoutine);
            Thread thread = new Thread(start);
            thread.Start();
        }
        
        private NtlmLegacySupplicantClient([Claims]NtlmSupplicantContract.Exp:Start! exp, PasswordEvidence! evidence)
        {
            _exp = new TRef<NtlmSupplicantContract.Exp:Start>(exp);
            _evidence = evidence;
        }
        
        TRef<NtlmSupplicantContract.Exp:Start>! _exp;
        
        readonly PasswordEvidence! _evidence;
        
        void ThreadServiceRoutine()
        {
            NtlmSupplicantContract.Exp! exp = _exp.Acquire();
            
            // DebugLine("Service thread started.");
            
            try {
            
                exp.SendSuccess();
            
                for (;;) {
                
                    switch receive {
                        case exp.ChannelClosed():
                            // DebugLine("Channel closed.");
                            return;
                        
                        case exp.GetResponse(exchallenge, type):
                            byte[]! challenge = Bitter.ToByteArray(exchallenge);
                            delete exchallenge;
                            
                            
                            byte[] response;
                            switch (type) {
                                case NtlmResponseType.LanMan:
                                    // DebugLine("Computing LanMan response");
                                    response = NtlmSupplicant.ComputeLmResponse(challenge, _evidence.Password);
                                    break;
                                    
                                case NtlmResponseType.WindowsNt:
                                    // DebugLine("Computing NT response");
                                    response = NtlmSupplicant.ComputeNtResponse(challenge, _evidence.Password);
                                    break;
                                    
                                default:
                                    DebugLine("Invalid arguments -- response type not supported");
                                    response = null;
                                    break;									
                            }
                            
                            if (response != null) {
                                byte[]! in ExHeap exresponse = Bitter.FromByteArray(response);
                                exp.SendResponse(exresponse);
                            }
                            else {
                                exp.SendRequestFailed(CredError.InvalidArguments);
                            }
                            break;
                    }
                }
            
            }
            catch (Exception ex) {
                DebugLine("EXCEPTION in NtlmLegacySupplicantClient service thread!");
                Util.DumpException(ex);

            }
            finally {
                delete exp;
            }
        }
        
        void DebugLine(string! line)
        {
            DebugStub.WriteLine("CREDMGR[NtlmLegacy]: " + line);
        }
        
        void DebugLine(string! format, params object[]! args)
        {
            DebugLine(String.Format(format, args));
        }	
    }

    ///
    //<summary>
    //  This class provides access to the NTLM supplicant using GSS.  GSS is a token-exchange model.
    //  This implementation uses standard NTLMSSP tokens, and is compatible with the Windows NTLM SSP
    //  implementation.
    //</summary>
    //
    class NtlmGssSupplicantClient
    {
        public static void StartServiceThread(
            [Claims]GssSupplicantContract.Exp:Start! exp,
            string! username,
            string! domain,
            PasswordEvidence! evidence)
        {
            NtlmGssSupplicantClient client = new NtlmGssSupplicantClient(exp, username, domain, evidence);
            ThreadStart start = new ThreadStart(client.ThreadServiceRoutine);
            Thread thread = new Thread(start);
            thread.Start();
        }
        
        private NtlmGssSupplicantClient(
            [Claims]GssSupplicantContract.Exp:Start! exp,
            string! username,
            string! domain,
            PasswordEvidence! evidence)
        {
            _exp = new TRef<GssSupplicantContract.Exp:Start>(exp);
            _evidence = evidence;
            _workstation = "SINGULARITY";
            _username = username;
            _domain = domain;
        }
        
        TRef<GssSupplicantContract.Exp:Start>! _exp;
        
        readonly PasswordEvidence! _evidence;
        readonly string! _username;
        readonly string! _domain;
        
        readonly string! _workstation;
        
        void ThreadServiceRoutine()
        {
            GssSupplicantContract.Exp! exp = _exp.Acquire();
            
            // DebugLine("Service thread started.");
            
            try {

                // In NTLM/GSS, the supplicant sends the first message (Negotiate).
                // This message contains the domain name and hostname of the local computer,
                // which Singularity doesn't really support right now.  So we'll use fixed values.
                
                byte[]! negotiate_token;
                try {
                    negotiate_token = NtlmSupplicant.GetNegotiate(
                        0,
                        "WORKGROUP",
                        _workstation);
                }
                catch (Exception ex) {
                    DebugLine("The NTLM supplicant threw an exception while trying to build the Negotiate token.");
                    Util.DumpException(ex);
                    return;
                }
                
                // DebugLine("Sending Negotiate token");
                exp.SendFirstToken(Bitter.FromByteArray(negotiate_token));
                
                // The supplicant channel is now in the WaitingForToken state.
            
                switch receive {
                    case exp.ChannelClosed():
                        // DebugLine("Channel closed.");
                        return;
                    
                    case exp.AcceptToken(byte[]! in ExHeap exchallenge_token):
                        byte[]! challenge_token = Bitter.ToByteArray(exchallenge_token);
                        delete exchallenge_token;
                        // DebugLine("Received Challenge token.");
                        byte[]! response_token;
                        try {
                            response_token = NtlmSupplicant.GetResponse(
                                challenge_token,
                                _domain,
                                _username,
                                _workstation,
                                _evidence.Password);
                        }
                        catch (Exception ex) {
                            DebugLine("The NTLM supplicant threw an exception while processing the Challenge token.");
                            Util.DumpException(ex);
                            exp.SendAuthenticationFailed(GssErrorCode.InternalError);
                            goto failed_state;
                        }
                        // DebugLine("Sending ContinueNeeded, with the Response token.");
                        byte[]! in ExHeap ex_response_token = Bitter.FromByteArray(response_token);
                        exp.SendCompleteWithToken(ex_response_token);
                        break;
                }
                
                //
                // At this point, we are in the "succeeded" state.
                // Which actually resembles the "failed" state, but this state will probably
                // have some real messages later.
                //
                // DebugLine("Authentication is complete, at least from our point of view.");
                
                for (;;) {
                    switch receive {
                        case exp.ChannelClosed():
                            return;
                    }
                }
                
            failed_state:
                for (;;) {
                    switch receive {
                        case exp.ChannelClosed():
                            return;
                    }
                }
                
            }
            catch (Exception ex) {
                DebugLine("EXCEPTION in NtlmSupplicant service thread!");
                Util.DumpException(ex);
            }
            finally {
                delete exp;
            }
        }
        
        void DebugLine(string! line)
        {
            DebugStub.WriteLine("CREDMGR[NtlmGss]: " + line);
        }
        
        void DebugLine(string! format, params object[]! args)
        {
            DebugLine(String.Format(format, args));
        }	
    }
}