Initial Commit

iTechSharp/srcbc/asn1/ASN1StreamParser.cs

@@ -0,0 +1,154 @@
+using System;
+using System.IO;
+
+namespace Org.BouncyCastle.Asn1
+{
+	public class Asn1StreamParser
+	{
+		private readonly Stream _in;
+		private readonly int _limit;
+
+		public Asn1StreamParser(
+			Stream inStream)
+			: this(inStream, int.MaxValue)
+		{
+		}
+
+		public Asn1StreamParser(
+			Stream	inStream,
+			int		limit)
+		{
+			if (!inStream.CanRead)
+				throw new ArgumentException("Expected stream to be readable", "inStream");
+
+			this._in = inStream;
+			this._limit = limit;
+		}
+
+		public Asn1StreamParser(
+			byte[] encoding)
+			: this(new MemoryStream(encoding, false), encoding.Length)
+		{
+		}
+
+		public virtual IAsn1Convertible ReadObject()
+		{
+			int tag = _in.ReadByte();
+			if (tag == -1)
+				return null;
+
+			// turn of looking for "00" while we resolve the tag
+			Set00Check(false);
+
+			//
+			// calculate tag number
+			//
+			int tagNo = 0;
+			if ((tag & Asn1Tags.Tagged) != 0 || (tag & Asn1Tags.Application) != 0)
+			{
+				tagNo = Asn1InputStream.ReadTagNumber(_in, tag);
+			}
+
+			bool isConstructed = (tag & Asn1Tags.Constructed) != 0;
+			int baseTagNo = tag & ~Asn1Tags.Constructed;
+
+			//
+			// calculate length
+			//
+			int length = Asn1InputStream.ReadLength(_in, _limit);
+
+			if (length < 0) // indefinite length method
+			{
+				if (!isConstructed)
+					throw new IOException("indefinite length primitive encoding encountered");
+
+				IndefiniteLengthInputStream indIn = new IndefiniteLengthInputStream(_in);
+
+				if ((tag & Asn1Tags.Tagged) != 0)
+				{
+					return new BerTaggedObjectParser(tag, tagNo, indIn);
+				}
+
+				Asn1StreamParser sp = new Asn1StreamParser(indIn);
+
+				// TODO There are other tags that may be constructed (e.g. BitString)
+				switch (baseTagNo)
+				{
+					case Asn1Tags.OctetString:
+						return new BerOctetStringParser(sp);
+					case Asn1Tags.Sequence:
+						return new BerSequenceParser(sp);
+					case Asn1Tags.Set:
+						return new BerSetParser(sp);
+					default:
+						throw new IOException("unknown BER object encountered");
+				}
+			}
+			else
+			{
+				DefiniteLengthInputStream defIn = new DefiniteLengthInputStream(_in, length);
+
+				if ((tag & Asn1Tags.Application) != 0)
+				{
+					return new DerApplicationSpecific(isConstructed, tagNo, defIn.ToArray());
+				}
+
+				if ((tag & Asn1Tags.Tagged) != 0)
+				{
+					return new BerTaggedObjectParser(tag, tagNo, defIn);
+				}
+
+				if (isConstructed)
+				{
+					// TODO There are other tags that may be constructed (e.g. BitString)
+					switch (baseTagNo)
+					{
+						case Asn1Tags.OctetString:
+							//
+							// yes, people actually do this...
+							//
+							return new BerOctetStringParser(new Asn1StreamParser(defIn));
+						case Asn1Tags.Sequence:
+							return new DerSequenceParser(new Asn1StreamParser(defIn));
+						case Asn1Tags.Set:
+							return new DerSetParser(new Asn1StreamParser(defIn));
+						default:
+							// TODO Add DerUnknownTagParser class?
+							return new DerUnknownTag(tag, defIn.ToArray());
+					}
+				}
+
+				// Some primitive encodings can be handled by parsers too...
+				switch (baseTagNo)
+				{
+					case Asn1Tags.OctetString:
+						return new DerOctetStringParser(defIn);
+				}
+
+				return Asn1InputStream.CreatePrimitiveDerObject(tag, defIn.ToArray());
+			}
+		}
+
+		private void Set00Check(
+			bool enabled)
+		{
+			if (_in is IndefiniteLengthInputStream)
+			{
+				((IndefiniteLengthInputStream) _in).SetEofOn00(enabled);
+			}
+		}
+
+		internal Asn1EncodableVector ReadVector()
+		{
+			Asn1EncodableVector v = new Asn1EncodableVector();
+
+			IAsn1Convertible obj;
+			while ((obj = ReadObject()) != null)
+			{
+				v.Add(obj.ToAsn1Object());
+			}
+
+			return v;
+		}
+	}
+}