_NtlmClient.cs source code in C# .NET

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                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Net / System / Net / _NtlmClient.cs / 1305376 / _NtlmClient.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Net { 
    using System.Collections; 
    using System.Security.Authentication.ExtendedProtection;
    using System.Security.Permissions; 
    using System.Globalization;

    internal class NtlmClient : ISessionAuthenticationModule {
 
        internal const string AuthType = "NTLM";
        internal static string Signature = AuthType.ToLower(CultureInfo.InvariantCulture); 
        internal static int SignatureSize = Signature.Length; 

        // 
        // RAID#95841
        // SSPI crashes without checking max length, so we need to check the sizes ourselves before
        // we call into SSPI. values are UNLEN, PWLEN and DNLEN taken from sdk\inc\lmcons.h
        // the fix in SSPI will make it to SP4 on win2k. 
        //
        internal const int MaxNtlmCredentialSize = 256 + 256 + 15; // UNLEN + PWLEN + DNLEN 
 
        public Authorization Authenticate(string challenge, WebRequest webRequest, ICredentials credentials) {
            GlobalLog.Print("NtlmClient::Authenticate() challenge:[" + ValidationHelper.ToString(challenge) + "] webRequest#" + ValidationHelper.HashString(webRequest) + " credentials#" + ValidationHelper.HashString(credentials) + " calling DoAuthenticate()"); 
            return DoAuthenticate(challenge, webRequest, credentials, false);
        }

        private Authorization DoAuthenticate(string challenge, WebRequest webRequest, ICredentials credentials, bool preAuthenticate) { 
            GlobalLog.Print("NtlmClient::DoAuthenticate() challenge:[" + ValidationHelper.ToString(challenge) + "] webRequest#" + ValidationHelper.HashString(webRequest) + " credentials#" + ValidationHelper.HashString(credentials) + " preAuthenticate:" + preAuthenticate.ToString());
 
            GlobalLog.Assert(credentials != null, "NtlmClient::DoAuthenticate()|credentials == null"); 
            if (credentials == null) {
                return null; 
            }

            HttpWebRequest httpWebRequest = webRequest as HttpWebRequest;
 
            GlobalLog.Assert(httpWebRequest != null, "NtlmClient::DoAuthenticate()|httpWebRequest == null");
            GlobalLog.Assert(httpWebRequest.ChallengedUri != null, "NtlmClient::DoAuthenticate()|httpWebRequest.ChallengedUri == null"); 
 
            NTAuthentication authSession = null;
            string incoming = null; 

            if (!preAuthenticate) {
                int index = AuthenticationManager.FindSubstringNotInQuotes(challenge, Signature);
                if (index < 0) { 
                    return null;
                } 
 
                int blobBegin = index + SignatureSize;
 
                //
                // there may be multiple challenges. If the next character after the
                // package name is not a comma then it is challenge data
                // 
                if (challenge.Length > blobBegin && challenge[blobBegin] != ',') {
                    ++blobBegin; 
                } 
                else {
                    index = -1; 
                }

                if (index >= 0 && challenge.Length > blobBegin)
                { 
                    // Strip other modules information in case of multiple challenges
                    // i.e do not take ", NTLM" as part of the following Negotiate blob 
                    // Negotiate TlRMTVNTUAACAAAADgAOADgAAAA1wo ... MAbwBmAHQALgBjAG8AbQAAAAAA,NTLM 
                    index = challenge.IndexOf(',', blobBegin);
                    if (index != -1) 
                        incoming = challenge.Substring(blobBegin, index - blobBegin);
                    else
                        incoming = challenge.Substring(blobBegin);
                } 

 
                authSession = httpWebRequest.CurrentAuthenticationState.GetSecurityContext(this); 
                GlobalLog.Print("NtlmClient::DoAuthenticate() key:" + ValidationHelper.HashString(httpWebRequest.CurrentAuthenticationState) + " retrieved authSession:" + ValidationHelper.HashString(authSession));
            } 

            if (authSession==null) {
                NetworkCredential NC = credentials.GetCredential(httpWebRequest.ChallengedUri, Signature);
                GlobalLog.Print("NtlmClient::DoAuthenticate() GetCredential() returns:" + ValidationHelper.ToString(NC)); 

                string username = string.Empty; 
                if (NC == null || (!(NC is SystemNetworkCredential) && (username = NC.InternalGetUserName()).Length == 0)) 
                {
                    return null; 
                }
                //
                // here we cover a hole in the SSPI layer. longer credentials
                // might corrupt the process and cause a reboot. 
                //
                if (username.Length + NC.InternalGetPassword().Length + NC.InternalGetDomain().Length>NtlmClient.MaxNtlmCredentialSize) { 
                    // 
                    // rather then throwing an exception here we return null so other packages can be used.
                    // this is questionable, hence: 
                    // Consider: make this throw a NotSupportedException so it is discoverable
                    //
                    return null;
                } 

                ICredentialPolicy policy = AuthenticationManager.CredentialPolicy; 
                if (policy != null && !policy.ShouldSendCredential(httpWebRequest.ChallengedUri, httpWebRequest, NC, this)) 
                    return null;
 
                string spn = httpWebRequest.CurrentAuthenticationState.GetComputeSpn(httpWebRequest);
                GlobalLog.Print("NtlmClient::Authenticate() ChallengedSpn:" + ValidationHelper.ToString(spn));

                ChannelBinding binding = null; 
                if (httpWebRequest.CurrentAuthenticationState.TransportContext != null)
                { 
                    binding = httpWebRequest.CurrentAuthenticationState.TransportContext.GetChannelBinding(ChannelBindingKind.Endpoint); 
                }
 
                authSession =
                    new NTAuthentication(
                        AuthType,
                        NC, 
                        spn,
                        httpWebRequest, 
                        binding); 

                GlobalLog.Print("NtlmClient::DoAuthenticate() setting SecurityContext for:" + ValidationHelper.HashString(httpWebRequest.CurrentAuthenticationState) + " to authSession:" + ValidationHelper.HashString(authSession)); 
                httpWebRequest.CurrentAuthenticationState.SetSecurityContext(authSession, this);
            }

            string clientResponse = authSession.GetOutgoingBlob(incoming); 
            if (clientResponse==null) {
                return null; 
            } 

            bool canShareConnection = httpWebRequest.UnsafeOrProxyAuthenticatedConnectionSharing; 
            if (canShareConnection) {
                httpWebRequest.LockConnection = true;
            }
 
            // this is the first leg of an NTLM handshake,
            // set the NtlmKeepAlive override *STRICTLY* only in this case. 
            httpWebRequest.NtlmKeepAlive = incoming==null; 

            return AuthenticationManager.GetGroupAuthorization(this, AuthType + " " + clientResponse, authSession.IsCompleted, authSession, canShareConnection, false); 
        }

        public bool CanPreAuthenticate {
            get { 
                return true;
            } 
        } 

        public Authorization PreAuthenticate(WebRequest webRequest, ICredentials credentials) { 
            GlobalLog.Print("NtlmClient::PreAuthenticate() webRequest#" + ValidationHelper.HashString(webRequest) + " credentials#" + ValidationHelper.HashString(credentials) + " calling DoAuthenticate()");
            return DoAuthenticate(null, webRequest, credentials, true);
        }
 
        public string AuthenticationType {
            get { 
                return AuthType; 
            }
        } 

        //
        // called when getting the final blob on the 200 OK from the server
        // 
        public bool Update(string challenge, WebRequest webRequest) {
            GlobalLog.Print("NtlmClient::Update(): " + challenge); 
 
            HttpWebRequest httpWebRequest = webRequest as HttpWebRequest;
 
            GlobalLog.Assert(httpWebRequest != null, "NtlmClient::Update()|httpWebRequest == null");
            GlobalLog.Assert(httpWebRequest.ChallengedUri != null, "NtlmClient::Update()|httpWebRequest.ChallengedUri == null");

            // 
            // try to retrieve the state of the ongoing handshake
            // 
            NTAuthentication authSession = httpWebRequest.CurrentAuthenticationState.GetSecurityContext(this); 
            GlobalLog.Print("NtlmClient::Update() key:" + ValidationHelper.HashString(httpWebRequest.CurrentAuthenticationState) + " retrieved authSession:" + ValidationHelper.HashString(authSession));
 
            if (authSession==null) {
                GlobalLog.Print("NtlmClient::Update() null session returning true");
                return true;
            } 

            GlobalLog.Print("NtlmClient::Update() authSession.IsCompleted:" + authSession.IsCompleted.ToString()); 
 
            if (!authSession.IsCompleted && httpWebRequest.CurrentAuthenticationState.StatusCodeMatch==httpWebRequest.ResponseStatusCode) {
                GlobalLog.Print("NtlmClient::Update() still handshaking (based on status code) returning false"); 
                return false;
            }

            ClearSession(httpWebRequest); 

            // now possibly close the ConnectionGroup after authentication is done. 
            if (!httpWebRequest.UnsafeOrProxyAuthenticatedConnectionSharing) { 
                GlobalLog.Print("NtlmClient::Update() releasing ConnectionGroup:" + httpWebRequest.GetConnectionGroupLine());
                httpWebRequest.ServicePoint.ReleaseConnectionGroup(httpWebRequest.GetConnectionGroupLine()); 
            }

            // Extract the CBT we used and cache it for future requests that want to do preauth
            httpWebRequest.ServicePoint.SetCachedChannelBinding(httpWebRequest.ChallengedUri, authSession.ChannelBinding); 

            GlobalLog.Print("NtlmClient::Update() session removed and ConnectionGorup released returning true"); 
            return true; 
        }
 
        public void ClearSession(WebRequest webRequest) {
            HttpWebRequest httpWebRequest = webRequest as HttpWebRequest;
            GlobalLog.Assert(httpWebRequest != null, "NtlmClient::ClearSession()|httpWebRequest == null");
            httpWebRequest.CurrentAuthenticationState.ClearSession(); 
        }
 
        public bool CanUseDefaultCredentials { 
            get {
                return true; 
            }
        }

    }; // class NtlmClient 

 
} // namespace System.Net 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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