1 files changed, 100 insertions, 0 deletions
diff --git a/crypto/src/asn1/DefiniteLengthInputStream.cs b/crypto/src/asn1/DefiniteLengthInputStream.cs
new file mode 100644
index 000000000..4ae803c0e
--- /dev/null
+++ b/crypto/src/asn1/DefiniteLengthInputStream.cs
@@ -0,0 +1,100 @@
+using System;
+using System.IO;
+
+using Org.BouncyCastle.Utilities.IO;
+
+namespace Org.BouncyCastle.Asn1
+{
+    class DefiniteLengthInputStream
+        : LimitedInputStream
+    {
+		private static readonly byte[] EmptyBytes = new byte[0];
+
+		private readonly int _originalLength;
+		private int _remaining;
+
+        internal DefiniteLengthInputStream(
+            Stream	inStream,
+            int		length)
+            : base(inStream, length)
+        {
+			if (length < 0)
+				throw new ArgumentException("negative lengths not allowed", "length");
+
+			this._originalLength = length;
+			this._remaining = length;
+
+			if (length == 0)
+			{
+				SetParentEofDetect(true);
+			}
+        }
+
+		internal int Remaining
+		{
+			get { return _remaining; }
+		}
+
+		public override int ReadByte()
+        {
+			if (_remaining == 0)
+				return -1;
+
+			int b = _in.ReadByte();
+
+			if (b < 0)
+				throw new EndOfStreamException("DEF length " + _originalLength + " object truncated by " + _remaining);
+
+			if (--_remaining == 0)
+			{
+				SetParentEofDetect(true);
+			}
+
+			return b;
+        }
+
+		public override int Read(
+			byte[]	buf,
+			int		off,
+			int		len)
+		{
+			if (_remaining == 0)
+				return 0;
+
+			int toRead = System.Math.Min(len, _remaining);
+			int numRead = _in.Read(buf, off, toRead);
+
+			if (numRead < 1)
+				throw new EndOfStreamException("DEF length " + _originalLength + " object truncated by " + _remaining);
+
+			if ((_remaining -= numRead) == 0)
+			{
+				SetParentEofDetect(true);
+			}
+
+			return numRead;
+		}
+
+        internal void ReadAllIntoByteArray(byte[] buf)
+        {
+            if (_remaining != buf.Length)
+                throw new ArgumentException("buffer length not right for data");
+
+            if ((_remaining -= Streams.ReadFully(_in, buf)) != 0)
+                throw new EndOfStreamException("DEF length " + _originalLength + " object truncated by " + _remaining);
+            SetParentEofDetect(true);
+        }
+
+        internal byte[] ToArray()
+		{
+			if (_remaining == 0)
+				return EmptyBytes;
+
+			byte[] bytes = new byte[_remaining];
+			if ((_remaining -= Streams.ReadFully(_in, bytes)) != 0)
+				throw new EndOfStreamException("DEF length " + _originalLength + " object truncated by " + _remaining);
+			SetParentEofDetect(true);
+			return bytes;
+		}
+    }
+}