// OCTET STRING SNMP data type.// Copyright (C) 2008-2010 Malcolm Crowe, Lex Li, and other contributors.// // Permission is hereby granted, free of charge, to any person obtaining a copy of this// software and associated documentation files (the "Software"), to deal in the Software// without restriction, including without limitation the rights to use, copy, modify, merge,// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons// to whom the Software is furnished to do so, subject to the following conditions:// // The above copyright notice and this permission notice shall be included in all copies or// substantial portions of the Software.// // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER// DEALINGS IN THE SOFTWARE. using System;using System.Globalization;using System.IO;using System.Linq;using System.Net.NetworkInformation;using System.Text; // ASN.1 BER encoding library by Malcolm Crowe at the University of the West of Scotland// See http://cis.paisley.ac.uk/crow-ci0// This is version 0 of the library, please advise me about any bugs// mailto:malcolm.crowe@paisley.ac.uk // Restrictions: It is assumed that no encoding has index length greater than 2^31-1.// UNIVERSAL TYPES// Some of the more unusual Universal encodings are supported but not fully implemented// Should you require these types, as an alternative to changing this code// you can catch the exception that is thrown and examine the contents yourself.// APPLICATION TYPES// If you want to handle Application types systematically, you can derive index class from// Universal, and provide the Creator and Creators methods for your class// You will see an example of how to do this in the Snmplib// CONTEXT AND PRIVATE TYPES// Ad hoc coding can be used for these, as an alterative to derive index class as above.namespace GSF.Net.Snmp{    /// <summary>    /// OctetString type.    /// </summary>    public sealed class OctetString // This namespace has its own concept of string        : ISnmpData, IEquatable<OctetString>    {        private static readonly OctetString EmptyString = new OctetString(string.Empty, Encoding.GetEncoding("ASCII"));                 // IMPORTANT: use GetEncoding because of CF.        private static Encoding _defaultEncoding = Encoding.GetEncoding("ASCII");        private readonly byte[] _raw;        private byte[] _length;         /// <summary>        /// Initializes a new instance of the <see cref="OctetString"/> class.        /// </summary>        /// <param name="length">The length.</param>        /// <param name="stream">The stream.</param>        public OctetString(Tuple<int, byte[]> length, Stream stream)        {            if (length == null)            {                throw new ArgumentNullException(nameof(length));            }             if (stream == null)            {                throw new ArgumentNullException(nameof(stream));            }             _raw = new byte[length.Item1];            stream.Read(_raw, 0, length.Item1);            Encoding = DefaultEncoding;            _length = length.Item2;        }                /// <summary>        /// Creates an <see cref="OctetString"/> from raw bytes.        /// </summary>        /// <param name="raw">Raw bytes</param>        public OctetString(byte[] raw)        {            if (raw == null)            {                throw new ArgumentNullException(nameof(raw));            }                        _raw = new byte[raw.Length];            Buffer.BlockCopy(raw, 0, _raw, 0, raw.Length);            Encoding = DefaultEncoding;        }                /// <summary>        /// Creates an <see cref="OctetString"/> with a specific <see cref="String"/>. This string is treated in specific <see cref="Encoding"/>.        /// </summary>        /// <param name="content">String.</param>        /// <param name="encoding">Encoding.</param>        public OctetString(string content, Encoding encoding)        {            Encoding = encoding;            _raw = Encoding.GetBytes(content);        }                /// <summary>        /// Creates an <see cref="OctetString"/> with a specific <see cref="String"/>. This string is treated as UTF-16.        /// </summary>        /// <param name="content">String.</param>        public OctetString(string content)            : this(content, DefaultEncoding)        {        }                /// <summary>        /// Creates an <see cref="OctetString"/> with a specific <see cref="Levels"/>.        /// </summary>        /// <param name="level"></param>        public OctetString(Levels level) : this(new[] { (byte)level })        {                    }         /// <summary>        /// Encoding of this <see cref="OctetString"/>        /// </summary>        public Encoding Encoding { get; private set; }         /// <summary>        /// Gets raw bytes.        /// </summary>        /// <returns></returns>        public byte[] GetRaw()        {            return _raw;        }                /// <summary>        /// Gets the empty string.        /// </summary>        /// <value>The empty.</value>        public static OctetString Empty        {            get { return EmptyString; }        }                       /// <summary>        /// Returns a <see cref="Levels"/> that represents this <see cref="OctetString"/>.        /// </summary>        /// <returns></returns>        public Levels ToLevels()        {                      byte[] bytes = GetRaw();            if (bytes.Length > 1)            {                throw new InvalidCastException("Length should be 1");            }             return (Levels)(bytes[0] & 7);        }                /// <summary>        /// Returns a <see cref="String"/> in a hex form that represents this <see cref="OctetString"/>.        /// </summary>        /// <returns></returns>        public string ToHexString()        {            StringBuilder result = new StringBuilder();            foreach (byte b in _raw)            {                result.Append(b.ToString("X2", CultureInfo.InvariantCulture));            }                        return result.ToString();        }                /// <summary>        /// Returns a <see cref="String"/> in a specific <see cref="Encoding"/> that represents this <see cref="OctetString"/>.        /// </summary>        /// <param name="encoding"></param>        /// <returns></returns>        public string ToString(Encoding encoding)        {            if (encoding == null)            {                throw new ArgumentNullException(nameof(encoding));            }             return encoding.GetString(_raw, 0, _raw.Length); // use this call for SL3.        }         /// <summary>        /// Returns a <see cref="String"/> in UTF-16 that represents this <see cref="OctetString"/>.        /// </summary>        /// <returns></returns>        public override string ToString()        {            return ToString(Encoding);        }                /// <summary>        /// Type code.        /// </summary>        public SnmpType TypeCode        {            get            {                return SnmpType.OctetString;            }        }         /// <summary>        /// Appends the bytes to <see cref="Stream"/>.        /// </summary>        /// <param name="stream">The stream.</param>        public void AppendBytesTo(Stream stream)        {            if (stream == null)            {                throw new ArgumentNullException(nameof(stream));            }             stream.AppendBytes(TypeCode, _length, _raw);        }         /// <summary>        /// Indicates whether the current object is equal to another object of the same type.        /// </summary>        /// <param name="other">An object to compare with this object.</param>        /// <returns><value>true</value> if the current object is equal to the <paramref name="other"/> parameter; otherwise, <value>false</value>.        /// </returns>        public bool Equals(OctetString other)        {            return Equals(this, other);        }                /// <summary>        /// Determines whether the specified <see cref="Object"/> is equal to the current <see cref="OctetString"/>.        /// </summary>        /// <param name="obj">The <see cref="Object"/> to compare with the current <see cref="OctetString"/>. </param>        /// <returns><value>true</value> if the specified <see cref="Object"/> is equal to the current <see cref="OctetString"/>; otherwise, <value>false</value>.        /// </returns>        public override bool Equals(object obj)        {            return Equals(this, obj as OctetString);        }                /// <summary>        /// Serves as a hash function for a particular type.        /// </summary>        /// <returns>A hash code for the current <see cref="OctetString"/>.</returns>        public override int GetHashCode()        {            return ToString(Encoding.Unicode).GetHashCode();        }                /// <summary>        /// The equality operator.        /// </summary>        /// <param name="left">Left <see cref="OctetString"/> object</param>        /// <param name="right">Right <see cref="OctetString"/> object</param>        /// <returns>        /// Returns <c>true</c> if the values of its operands are equal, <c>false</c> otherwise.</returns>        public static bool operator ==(OctetString left, OctetString right)        {            return Equals(left, right);        }                /// <summary>        /// The inequality operator.        /// </summary>        /// <param name="left">Left <see cref="OctetString"/> object</param>        /// <param name="right">Right <see cref="OctetString"/> object</param>        /// <returns>        /// Returns <c>true</c> if the values of its operands are not equal, <c>false</c> otherwise.</returns>        public static bool operator !=(OctetString left, OctetString right)        {            return !(left == right);        } #if !NETFX_CORE        /// <summary>        /// Converts octets to physical address.        /// </summary>        /// <returns></returns>        public PhysicalAddress ToPhysicalAddress()        {            if (_raw.Length != 6)            {                throw new InvalidCastException(string.Format(CultureInfo.InvariantCulture, "the data length is not equal to 6: {0}", _raw.Length));            }             return new PhysicalAddress(_raw);        }#endif         /// <summary>        /// Default encoding of <see cref="OctetString"/> type.        /// </summary>        public static Encoding DefaultEncoding        {            get { return _defaultEncoding; }            set { _defaultEncoding = value; }        }                /// <summary>        /// The comparison.        /// </summary>        /// <param name="left">Left <see cref="OctetString"/> object</param>        /// <param name="right">Right <see cref="OctetString"/> object</param>        /// <returns>        /// Returns <c>true</c> if the values of its operands are not equal, <c>false</c> otherwise.</returns>        private static bool Equals(OctetString left, OctetString right)        {            object lo = left;            object ro = right;            if (lo == ro)            {                return true;            }             if (lo == null || ro == null)            {                return false;            }             return left._raw.SequenceEqual(right._raw);         }         internal byte[] GetLengthBytes()        {            return _length;        }         internal void SetLengthBytes(byte[] bytes)        {            _length = bytes;        }         /// <summary>        /// Indicates whether the specified <see cref="OctetString" /> object is a null reference (<c>Nothing</c> in Visual Basic) or an <see cref="Empty" /> string.        /// </summary>        /// <param name="value">A <see cref="OctetString" /> reference.</param>        /// <returns><c>true</c> if the <paramref name="value"/> parameter is a null reference (<c>Nothing</c> in Visual Basic) or an empty string (""); otherwise, <c>false</c>.</returns>        public static bool IsNullOrEmpty(OctetString value)        {            if (value == null)            {                return true;            }             if (value == Empty)            {                return true;            }             return false;        }    }        // all references here are to ITU-X.690-12/97}