155 lines
3.5 KiB
C#
155 lines
3.5 KiB
C#
using System;
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using System.IO;
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namespace Org.BouncyCastle.Asn1
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{
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public class Asn1StreamParser
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{
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private readonly Stream _in;
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private readonly int _limit;
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public Asn1StreamParser(
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Stream inStream)
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: this(inStream, int.MaxValue)
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{
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}
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public Asn1StreamParser(
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Stream inStream,
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int limit)
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{
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if (!inStream.CanRead)
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throw new ArgumentException("Expected stream to be readable", "inStream");
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this._in = inStream;
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this._limit = limit;
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}
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public Asn1StreamParser(
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byte[] encoding)
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: this(new MemoryStream(encoding, false), encoding.Length)
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{
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}
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public virtual IAsn1Convertible ReadObject()
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{
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int tag = _in.ReadByte();
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if (tag == -1)
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return null;
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// turn of looking for "00" while we resolve the tag
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Set00Check(false);
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//
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// calculate tag number
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//
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int tagNo = 0;
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if ((tag & Asn1Tags.Tagged) != 0 || (tag & Asn1Tags.Application) != 0)
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{
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tagNo = Asn1InputStream.ReadTagNumber(_in, tag);
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}
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bool isConstructed = (tag & Asn1Tags.Constructed) != 0;
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int baseTagNo = tag & ~Asn1Tags.Constructed;
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//
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// calculate length
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//
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int length = Asn1InputStream.ReadLength(_in, _limit);
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if (length < 0) // indefinite length method
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{
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if (!isConstructed)
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throw new IOException("indefinite length primitive encoding encountered");
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IndefiniteLengthInputStream indIn = new IndefiniteLengthInputStream(_in);
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if ((tag & Asn1Tags.Tagged) != 0)
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{
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return new BerTaggedObjectParser(tag, tagNo, indIn);
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}
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Asn1StreamParser sp = new Asn1StreamParser(indIn);
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// TODO There are other tags that may be constructed (e.g. BitString)
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switch (baseTagNo)
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{
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case Asn1Tags.OctetString:
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return new BerOctetStringParser(sp);
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case Asn1Tags.Sequence:
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return new BerSequenceParser(sp);
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case Asn1Tags.Set:
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return new BerSetParser(sp);
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default:
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throw new IOException("unknown BER object encountered");
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}
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}
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else
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{
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DefiniteLengthInputStream defIn = new DefiniteLengthInputStream(_in, length);
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if ((tag & Asn1Tags.Application) != 0)
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{
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return new DerApplicationSpecific(isConstructed, tagNo, defIn.ToArray());
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}
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if ((tag & Asn1Tags.Tagged) != 0)
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{
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return new BerTaggedObjectParser(tag, tagNo, defIn);
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}
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if (isConstructed)
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{
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// TODO There are other tags that may be constructed (e.g. BitString)
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switch (baseTagNo)
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{
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case Asn1Tags.OctetString:
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//
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// yes, people actually do this...
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//
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return new BerOctetStringParser(new Asn1StreamParser(defIn));
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case Asn1Tags.Sequence:
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return new DerSequenceParser(new Asn1StreamParser(defIn));
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case Asn1Tags.Set:
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return new DerSetParser(new Asn1StreamParser(defIn));
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default:
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// TODO Add DerUnknownTagParser class?
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return new DerUnknownTag(tag, defIn.ToArray());
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}
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}
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// Some primitive encodings can be handled by parsers too...
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switch (baseTagNo)
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{
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case Asn1Tags.OctetString:
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return new DerOctetStringParser(defIn);
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}
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return Asn1InputStream.CreatePrimitiveDerObject(tag, defIn.ToArray());
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}
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}
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private void Set00Check(
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bool enabled)
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{
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if (_in is IndefiniteLengthInputStream)
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{
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((IndefiniteLengthInputStream) _in).SetEofOn00(enabled);
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}
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}
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internal Asn1EncodableVector ReadVector()
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{
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Asn1EncodableVector v = new Asn1EncodableVector();
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IAsn1Convertible obj;
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while ((obj = ReadObject()) != null)
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{
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v.Add(obj.ToAsn1Object());
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}
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return v;
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}
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}
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}
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