NonceCache.cs source code in C# .NET

                        Code:
                         / WCF / WCF / 3.5.30729.1 / untmp / Orcas / SP / ndp / cdf / src / WCF / ServiceModel / System / ServiceModel / Security / NonceCache.cs / 1 / NonceCache.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------

namespace System.ServiceModel.Security 
{
    using System.Collections; 
    using System.Globalization; 
    using System.IO;
 
    /// 
    /// This is the in-memory nonce-cache used for turnkey replay detection.
    /// The nonce cache is based on a hashtable implementation for fast lookups.
    /// The hashcode is computed based on the nonce byte array. 
    /// The nonce cache periodically purges stale nonce entries.
    ///  
    sealed class NonceCache 
    {
        NonceCacheImpl cacheImpl; 
        TimeSpan cachingTime;
        int maxCachedNonces;

        public NonceCache(TimeSpan cachingTime, int maxCachedNonces) 
        {
            if (cachingTime <= TimeSpan.Zero) 
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("cachingTime", SR.GetString(SR.TimeSpanMustbeGreaterThanTimeSpanZero)));
            } 
            this.cacheImpl = new NonceCacheImpl(cachingTime, maxCachedNonces);
            this.cachingTime = cachingTime;
            this.maxCachedNonces = maxCachedNonces;
        } 

        public TimeSpan CachingTimeSpan 
        { 
            get
            { 
                return this.cachingTime;
            }
        }
 
        public int MaxCachedNonces
        { 
            get 
            {
                return this.maxCachedNonces; 
            }
        }

        public bool CheckNonce(byte[] nonce) 
        {
            return this.cacheImpl.CheckNonce(nonce); 
        } 

        public bool TryAddNonce(byte[] nonce) 
        {
            return this.cacheImpl.TryAddNonce(nonce);
        }
 
        public override string ToString()
        { 
            StringWriter writer = new StringWriter(CultureInfo.InvariantCulture); 
            writer.WriteLine("NonceCache:");
            writer.WriteLine("   Caching Timespan: {0}", this.CachingTimeSpan); 
            writer.WriteLine("   Capacity: {0}", this.MaxCachedNonces);
            return writer.ToString();
        }
 
        internal sealed class NonceCacheImpl : TimeBoundedCache
        { 
            static NonceKeyComparer comparer = new NonceKeyComparer(); 
            static object dummyItem = new Object();
            // if there are less than lowWaterMark entries, no purging is done 
            static int lowWaterMark = 50;
            // We created a key for the nonce using the first 4 bytes, and hence the minimum length of nonce
            // that can be added to the cache.
            static int minimumNonceLength = 4; 
            TimeSpan cachingTimeSpan;
 
            public NonceCacheImpl(TimeSpan cachingTimeSpan, int maxCachedNonces) 
                : base(lowWaterMark, maxCachedNonces, comparer, PurgingMode.AccessBasedPurge, TimeSpan.FromTicks(cachingTimeSpan.Ticks >> 2), false)
            { 
                this.cachingTimeSpan = cachingTimeSpan;
            }

            public bool TryAddNonce(byte[] nonce) 
            {
                if (nonce == null) 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("nonce"); 
                if (nonce.Length < minimumNonceLength)
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgument(SR.GetString(SR.NonceLengthTooShort)); 
                DateTime expirationTime = TimeoutHelper.Add(DateTime.UtcNow, this.cachingTimeSpan);
                return base.TryAddItem(nonce, dummyItem, expirationTime, false);
            }
 
            public bool CheckNonce(byte[] nonce)
            { 
                if (nonce == null) 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("nonce");
                if (nonce.Length < minimumNonceLength) 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgument(SR.GetString(SR.NonceLengthTooShort));
                if (base.GetItem(nonce) != null)
                    return true;
                else 
                    return false;
            } 
 
            /// 
            /// This class provides the hash-code value for the key (nonce) of the nonce cache. 
            /// The hash code is obtained from the nonce byte array  by making an int of
            /// the first 4 bytes
            /// 
            internal sealed class NonceKeyComparer : IEqualityComparer, System.Collections.Generic.IEqualityComparer 
            {
                public int GetHashCode(object o) 
                { 
                    return GetHashCode((byte[])o);
                } 
                public int GetHashCode(byte[] o)
                {
                    byte[] nonce = (byte[])o;
 
                    return (((int)nonce[0]) | (((int)nonce[1]) << 8) | (((int)nonce[2]) << 16) | (((int)nonce[3]) << 24));
                } 
 
                public int Compare(object x, object y)
                { 
                    return Compare((byte[])x, (byte[])y);
                }

                public int Compare(byte[] x, byte[] y) 
                {
                    if (Object.ReferenceEquals(x, y)) 
                        return 0; 

                    if (x == null) 
                        return -1;
                    else if (y == null)
                        return 1;
 
                    byte[] nonce1 = (byte[])x;
                    int length1 = nonce1.Length; 
                    byte[] nonce2 = (byte[])y; 
                    int length2 = nonce2.Length;
 
                    if (length1 == length2)
                    {
                        for (int i = 0; i < length1; ++i)
                        { 
                            int diff = ((int)nonce1[i] - (int)nonce2[i]);
 
                            if (diff != 0) 
                            {
                                return diff; 
                            }
                        }

                        return 0; 
                    }
                    else if (length1 > length2) 
                    { 
                        return 1;
                    } 
                    else
                    {
                        return -1;
                    } 
                }
 
                public new bool Equals(object x, object y) 
                {
                    return (Compare(x, y) == 0); 
                }

                public bool Equals(byte[] x, byte[] y)
                { 
                    return (Compare(x, y) == 0);
                } 
            } 
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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NonceCache.cs source code in C# .NET

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