_NtlmClient.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Net / System / Net / _NtlmClient.cs / 1 / _NtlmClient.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Net { 
    using System.Collections; 
    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; 

                authSession = 
                    new NTAuthentication(
                        AuthType,
                        NC,
                        null, 
                        httpWebRequest);
 
                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()); 
            }
 
            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
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