340 lines
8.1 KiB
C#
340 lines
8.1 KiB
C#
//
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// ASN1.cs: Abstract Syntax Notation 1 - micro-parser and generator
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//
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// Authors:
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// Sebastien Pouliot <sebastien@ximian.com>
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// Jesper Pedersen <jep@itplus.dk>
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//
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// (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
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// Copyright (C) 2004 Novell, Inc (http://www.novell.com)
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// (C) 2004 IT+ A/S (http://www.itplus.dk)
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//
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// Permission is hereby granted, free of charge, to any person obtaining
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// a copy of this software and associated documentation files (the
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// "Software"), to deal in the Software without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Software, and to
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// permit persons to whom the Software is furnished to do so, subject to
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// the following conditions:
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//
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// The above copyright notice and this permission notice shall be
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// included in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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//
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using System;
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using System.Collections;
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using System.IO;
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using System.Text;
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namespace Emby.Common.Implementations.Security {
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// References:
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// a. ITU ASN.1 standards (free download)
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// http://www.itu.int/ITU-T/studygroups/com17/languages/
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public class ASN1 {
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private byte m_nTag;
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private byte[] m_aValue;
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private ArrayList elist;
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public ASN1 () : this (0x00, null) {}
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public ASN1 (byte tag) : this (tag, null) {}
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public ASN1 (byte tag, byte[] data)
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{
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m_nTag = tag;
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m_aValue = data;
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}
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public ASN1 (byte[] data)
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{
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m_nTag = data [0];
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int nLenLength = 0;
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int nLength = data [1];
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if (nLength > 0x80) {
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// composed length
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nLenLength = nLength - 0x80;
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nLength = 0;
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for (int i = 0; i < nLenLength; i++) {
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nLength *= 256;
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nLength += data [i + 2];
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}
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}
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else if (nLength == 0x80) {
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// undefined length encoding
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throw new NotSupportedException ("Undefined length encoding.");
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}
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m_aValue = new byte [nLength];
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Buffer.BlockCopy (data, (2 + nLenLength), m_aValue, 0, nLength);
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if ((m_nTag & 0x20) == 0x20) {
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int nStart = (2 + nLenLength);
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Decode (data, ref nStart, data.Length);
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}
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}
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public int Count {
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get {
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if (elist == null)
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return 0;
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return elist.Count;
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}
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}
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public byte Tag {
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get { return m_nTag; }
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}
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public int Length {
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get {
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if (m_aValue != null)
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return m_aValue.Length;
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else
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return 0;
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}
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}
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public byte[] Value {
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get {
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if (m_aValue == null)
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GetBytes ();
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return (byte[]) m_aValue.Clone ();
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}
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set {
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if (value != null)
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m_aValue = (byte[]) value.Clone ();
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}
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}
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private bool CompareArray (byte[] array1, byte[] array2)
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{
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bool bResult = (array1.Length == array2.Length);
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if (bResult) {
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for (int i = 0; i < array1.Length; i++) {
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if (array1[i] != array2[i])
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return false;
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}
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}
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return bResult;
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}
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public bool Equals (byte[] asn1)
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{
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return CompareArray (this.GetBytes (), asn1);
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}
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public bool CompareValue (byte[] value)
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{
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return CompareArray (m_aValue, value);
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}
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public ASN1 Add (ASN1 asn1)
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{
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if (asn1 != null) {
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if (elist == null)
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elist = new ArrayList ();
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elist.Add (asn1);
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}
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return asn1;
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}
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public virtual byte[] GetBytes ()
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{
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byte[] val = null;
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if (Count > 0) {
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int esize = 0;
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ArrayList al = new ArrayList ();
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foreach (ASN1 a in elist) {
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byte[] item = a.GetBytes ();
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al.Add (item);
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esize += item.Length;
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}
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val = new byte [esize];
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int pos = 0;
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for (int i=0; i < elist.Count; i++) {
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byte[] item = (byte[]) al[i];
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Buffer.BlockCopy (item, 0, val, pos, item.Length);
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pos += item.Length;
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}
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} else if (m_aValue != null) {
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val = m_aValue;
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}
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byte[] der;
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int nLengthLen = 0;
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if (val != null) {
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int nLength = val.Length;
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// special for length > 127
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if (nLength > 127) {
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if (nLength <= Byte.MaxValue) {
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der = new byte [3 + nLength];
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Buffer.BlockCopy (val, 0, der, 3, nLength);
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nLengthLen = 0x81;
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der[2] = (byte)(nLength);
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}
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else if (nLength <= UInt16.MaxValue) {
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der = new byte [4 + nLength];
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Buffer.BlockCopy (val, 0, der, 4, nLength);
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nLengthLen = 0x82;
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der[2] = (byte)(nLength >> 8);
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der[3] = (byte)(nLength);
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}
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else if (nLength <= 0xFFFFFF) {
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// 24 bits
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der = new byte [5 + nLength];
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Buffer.BlockCopy (val, 0, der, 5, nLength);
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nLengthLen = 0x83;
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der [2] = (byte)(nLength >> 16);
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der [3] = (byte)(nLength >> 8);
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der [4] = (byte)(nLength);
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}
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else {
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// max (Length is an integer) 32 bits
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der = new byte [6 + nLength];
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Buffer.BlockCopy (val, 0, der, 6, nLength);
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nLengthLen = 0x84;
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der [2] = (byte)(nLength >> 24);
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der [3] = (byte)(nLength >> 16);
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der [4] = (byte)(nLength >> 8);
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der [5] = (byte)(nLength);
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}
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}
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else {
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// basic case (no encoding)
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der = new byte [2 + nLength];
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Buffer.BlockCopy (val, 0, der, 2, nLength);
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nLengthLen = nLength;
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}
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if (m_aValue == null)
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m_aValue = val;
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}
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else
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der = new byte[2];
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der[0] = m_nTag;
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der[1] = (byte)nLengthLen;
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return der;
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}
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// Note: Recursive
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protected void Decode (byte[] asn1, ref int anPos, int anLength)
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{
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byte nTag;
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int nLength;
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byte[] aValue;
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// minimum is 2 bytes (tag + length of 0)
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while (anPos < anLength - 1) {
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DecodeTLV (asn1, ref anPos, out nTag, out nLength, out aValue);
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// sometimes we get trailing 0
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if (nTag == 0)
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continue;
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ASN1 elm = Add (new ASN1 (nTag, aValue));
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if ((nTag & 0x20) == 0x20) {
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int nConstructedPos = anPos;
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elm.Decode (asn1, ref nConstructedPos, nConstructedPos + nLength);
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}
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anPos += nLength; // value length
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}
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}
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// TLV : Tag - Length - Value
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protected void DecodeTLV (byte[] asn1, ref int pos, out byte tag, out int length, out byte[] content)
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{
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tag = asn1 [pos++];
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length = asn1 [pos++];
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// special case where L contains the Length of the Length + 0x80
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if ((length & 0x80) == 0x80) {
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int nLengthLen = length & 0x7F;
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length = 0;
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for (int i = 0; i < nLengthLen; i++)
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length = length * 256 + asn1 [pos++];
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}
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content = new byte [length];
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Buffer.BlockCopy (asn1, pos, content, 0, length);
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}
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public ASN1 this [int index] {
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get {
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try {
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if ((elist == null) || (index >= elist.Count))
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return null;
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return (ASN1) elist [index];
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}
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catch (ArgumentOutOfRangeException) {
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return null;
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}
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}
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}
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public ASN1 Element (int index, byte anTag)
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{
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try {
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if ((elist == null) || (index >= elist.Count))
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return null;
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ASN1 elm = (ASN1) elist [index];
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if (elm.Tag == anTag)
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return elm;
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else
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return null;
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}
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catch (ArgumentOutOfRangeException) {
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return null;
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}
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}
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public override string ToString()
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{
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StringBuilder hexLine = new StringBuilder ();
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// Add tag
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hexLine.AppendFormat ("Tag: {0} {1}", m_nTag.ToString ("X2"), Environment.NewLine);
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// Add length
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hexLine.AppendFormat ("Length: {0} {1}", Value.Length, Environment.NewLine);
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// Add value
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hexLine.Append ("Value: ");
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hexLine.Append (Environment.NewLine);
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for (int i = 0; i < Value.Length; i++) {
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hexLine.AppendFormat ("{0} ", Value [i].ToString ("X2"));
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if ((i+1) % 16 == 0)
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hexLine.AppendFormat (Environment.NewLine);
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}
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return hexLine.ToString ();
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}
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public void SaveToFile (string filename)
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{
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if (filename == null)
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throw new ArgumentNullException ("filename");
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using (FileStream fs = File.Create (filename)) {
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byte[] data = GetBytes ();
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fs.Write (data, 0, data.Length);
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}
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}
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}
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}
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