1 files changed, 63 insertions, 0 deletions
diff --git a/crypto/src/bcpg/UserAttributeSubpacketsReader.cs b/crypto/src/bcpg/UserAttributeSubpacketsReader.cs
new file mode 100644
index 000000000..2e5ea0f3e
--- /dev/null
+++ b/crypto/src/bcpg/UserAttributeSubpacketsReader.cs
@@ -0,0 +1,63 @@
+using System;
+using System.IO;
+using Org.BouncyCastle.Bcpg.Attr;
+using Org.BouncyCastle.Utilities.IO;
+
+namespace Org.BouncyCastle.Bcpg
+{
+	/**
+	* reader for user attribute sub-packets
+	*/
+	public class UserAttributeSubpacketsParser
+	{
+		private readonly Stream input;
+
+		public UserAttributeSubpacketsParser(
+			Stream input)
+		{
+			this.input = input;
+		}
+
+		public UserAttributeSubpacket ReadPacket()
+		{
+			int l = input.ReadByte();
+			if (l < 0)
+				return null;
+
+			int bodyLen = 0;
+			if (l < 192)
+			{
+				bodyLen = l;
+			}
+			else if (l <= 223)
+			{
+				bodyLen = ((l - 192) << 8) + (input.ReadByte()) + 192;
+			}
+			else if (l == 255)
+			{
+				bodyLen = (input.ReadByte() << 24) | (input.ReadByte() << 16)
+					|  (input.ReadByte() << 8)  | input.ReadByte();
+			}
+			else
+			{
+				// TODO Error?
+			}
+
+			int tag = input.ReadByte();
+			if (tag < 0)
+				throw new EndOfStreamException("unexpected EOF reading user attribute sub packet");
+
+			byte[] data = new byte[bodyLen - 1];
+			if (Streams.ReadFully(input, data) < data.Length)
+				throw new EndOfStreamException();
+
+			UserAttributeSubpacketTag type = (UserAttributeSubpacketTag) tag;
+			switch (type)
+			{
+				case UserAttributeSubpacketTag.ImageAttribute:
+					return new ImageAttrib(data);
+			}
+			return new UserAttributeSubpacket(type, data);
+		}
+	}
+}