Improve ASN.1 substream handling

2 files changed, 83 insertions, 77 deletions

diff --git a/crypto/src/asn1/ASN1StreamParser.cs b/crypto/src/asn1/ASN1StreamParser.cs
index 860dc99b1..cca333412 100644
--- a/crypto/src/asn1/ASN1StreamParser.cs
+++ b/crypto/src/asn1/ASN1StreamParser.cs
@@ -10,31 +10,32 @@ namespace Org.BouncyCastle.Asn1
 
         private readonly byte[][] tmpBuffers;
 
-        public Asn1StreamParser(
-			Stream inStream)
-			: this(inStream, Asn1InputStream.FindLimit(inStream))
+        public Asn1StreamParser(Stream input)
+			: this(input, Asn1InputStream.FindLimit(input))
 		{
 		}
 
-		public Asn1StreamParser(
-			Stream	inStream,
-			int		limit)
-		{
-			if (!inStream.CanRead)
-				throw new ArgumentException("Expected stream to be readable", "inStream");
-
-			this._in = inStream;
-			this._limit = limit;
-            this.tmpBuffers = new byte[16][];
+        public Asn1StreamParser(byte[] encoding)
+            : this(new MemoryStream(encoding, false), encoding.Length)
+        {
         }
 
-		public Asn1StreamParser(
-			byte[] encoding)
-			: this(new MemoryStream(encoding, false), encoding.Length)
+        public Asn1StreamParser(Stream input, int limit)
+            : this(input, limit, new byte[16][])
 		{
-		}
+        }
+
+        internal Asn1StreamParser(Stream input, int limit, byte[][] tmpBuffers)
+        {
+            if (!input.CanRead)
+                throw new ArgumentException("Expected stream to be readable", "input");
+
+            this._in = input;
+            this._limit = limit;
+            this.tmpBuffers = tmpBuffers;
+        }
 
-		internal IAsn1Convertible ReadIndef(int tagValue)
+        internal IAsn1Convertible ReadIndef(int tagValue)
 		{
 			// Note: INDEF => CONSTRUCTED
 
@@ -142,10 +143,10 @@ namespace Org.BouncyCastle.Asn1
 				if (!isConstructed)
 					throw new IOException("indefinite-length primitive encoding encountered");
 
-				IndefiniteLengthInputStream indIn = new IndefiniteLengthInputStream(_in, _limit);
-				Asn1StreamParser sp = new Asn1StreamParser(indIn, _limit);
+                IndefiniteLengthInputStream indIn = new IndefiniteLengthInputStream(_in, _limit);
+                Asn1StreamParser sp = new Asn1StreamParser(indIn, _limit, tmpBuffers);
 
-				if ((tag & Asn1Tags.Application) != 0)
+                if ((tag & Asn1Tags.Application) != 0)
 				{
 					return new BerApplicationSpecificParser(tagNo, sp);
 				}
@@ -168,45 +169,48 @@ namespace Org.BouncyCastle.Asn1
 
 				if ((tag & Asn1Tags.Tagged) != 0)
 				{
-					return new BerTaggedObjectParser(isConstructed, tagNo, new Asn1StreamParser(defIn));
+					return new BerTaggedObjectParser(isConstructed, tagNo,
+                        new Asn1StreamParser(defIn, defIn.Remaining, tmpBuffers));
 				}
 
-				if (isConstructed)
-				{
-					// TODO There are other tags that may be constructed (e.g. BitString)
-					switch (tagNo)
-					{
-						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));
-						case Asn1Tags.External:
-							return new DerExternalParser(new Asn1StreamParser(defIn));
-						default:
-                            throw new IOException("unknown tag " + tagNo + " encountered");
+                if (!isConstructed)
+                {
+                    // Some primitive encodings can be handled by parsers too...
+                    switch (tagNo)
+                    {
+                        case Asn1Tags.OctetString:
+                            return new DerOctetStringParser(defIn);
                     }
-				}
 
-				// Some primitive encodings can be handled by parsers too...
-				switch (tagNo)
-				{
-					case Asn1Tags.OctetString:
-						return new DerOctetStringParser(defIn);
-				}
+                    try
+                    {
+                        return Asn1InputStream.CreatePrimitiveDerObject(tagNo, defIn, tmpBuffers);
+                    }
+                    catch (ArgumentException e)
+                    {
+                        throw new Asn1Exception("corrupted stream detected", e);
+                    }
+                }
 
-				try
-				{
-					return Asn1InputStream.CreatePrimitiveDerObject(tagNo, defIn, tmpBuffers);
-				}
-				catch (ArgumentException e)
+                Asn1StreamParser sp = new Asn1StreamParser(defIn, defIn.Remaining, tmpBuffers);
+
+                // TODO There are other tags that may be constructed (e.g. BitString)
+                switch (tagNo)
 				{
-					throw new Asn1Exception("corrupted stream detected", e);
-				}
+					case Asn1Tags.OctetString:
+						//
+						// yes, people actually do this...
+						//
+						return new BerOctetStringParser(sp);
+					case Asn1Tags.Sequence:
+						return new DerSequenceParser(sp);
+					case Asn1Tags.Set:
+						return new DerSetParser(sp);
+					case Asn1Tags.External:
+						return new DerExternalParser(sp);
+					default:
+                        throw new IOException("unknown tag " + tagNo + " encountered");
+                }
 			}
 		}
 
diff --git a/crypto/src/asn1/Asn1InputStream.cs b/crypto/src/asn1/Asn1InputStream.cs
index 6bb6311e1..ff3590122 100644
--- a/crypto/src/asn1/Asn1InputStream.cs
+++ b/crypto/src/asn1/Asn1InputStream.cs
@@ -37,39 +37,40 @@ namespace Org.BouncyCastle.Asn1
             return int.MaxValue;
         }
 
-        public Asn1InputStream(
-            Stream inputStream)
-            : this(inputStream, FindLimit(inputStream))
+        public Asn1InputStream(Stream input)
+            : this(input, FindLimit(input))
         {
         }
 
         /**
-         * Create an ASN1InputStream where no DER object will be longer than limit.
+         * Create an ASN1InputStream based on the input byte array. The length of DER objects in
+         * the stream is automatically limited to the length of the input array.
          *
-         * @param input stream containing ASN.1 encoded data.
-         * @param limit maximum size of a DER encoded object.
+         * @param input array containing ASN.1 encoded data.
          */
-        public Asn1InputStream(
-            Stream	inputStream,
-            int		limit)
-            : base(inputStream)
+        public Asn1InputStream(byte[] input)
+            : this(new MemoryStream(input, false), input.Length)
         {
-            this.limit = limit;
-            this.tmpBuffers = new byte[16][];
         }
 
         /**
-         * Create an ASN1InputStream based on the input byte array. The length of DER objects in
-         * the stream is automatically limited to the length of the input array.
+         * Create an ASN1InputStream where no DER object will be longer than limit.
          *
-         * @param input array containing ASN.1 encoded data.
+         * @param input stream containing ASN.1 encoded data.
+         * @param limit maximum size of a DER encoded object.
          */
-        public Asn1InputStream(
-            byte[] input)
-            : this(new MemoryStream(input, false), input.Length)
+        public Asn1InputStream(Stream input, int limit)
+            : this(input, limit, new byte[16][])
         {
         }
 
+        private Asn1InputStream(Stream input, int limit, byte[][] tmpBuffers)
+            : base(input)
+        {
+            this.limit = limit;
+            this.tmpBuffers = tmpBuffers;
+        }
+
         /**
         * build an object given its tag and the number of bytes to construct it from.
         */
@@ -89,7 +90,7 @@ namespace Org.BouncyCastle.Asn1
 
             if ((tag & Asn1Tags.Tagged) != 0)
             {
-                return new Asn1StreamParser(defIn).ReadTaggedObject(isConstructed, tagNo);
+                return new Asn1StreamParser(defIn, defIn.Remaining, tmpBuffers).ReadTaggedObject(isConstructed, tagNo);
             }
 
             if (isConstructed)
@@ -148,12 +149,13 @@ namespace Org.BouncyCastle.Asn1
             return v;
         }
 
-        internal virtual Asn1EncodableVector ReadVector(DefiniteLengthInputStream dIn)
+        internal virtual Asn1EncodableVector ReadVector(DefiniteLengthInputStream defIn)
         {
-            if (dIn.Remaining < 1)
+            int remaining = defIn.Remaining;
+            if (remaining < 1)
                 return new Asn1EncodableVector(0);
 
-            return new Asn1InputStream(dIn).ReadVector();
+            return new Asn1InputStream(defIn, remaining, tmpBuffers).ReadVector();
         }
 
         internal virtual DerSequence CreateDerSequence(
@@ -197,7 +199,7 @@ namespace Org.BouncyCastle.Asn1
                     throw new IOException("indefinite-length primitive encoding encountered");
 
                 IndefiniteLengthInputStream indIn = new IndefiniteLengthInputStream(this.s, limit);
-                Asn1StreamParser sp = new Asn1StreamParser(indIn, limit);
+                Asn1StreamParser sp = new Asn1StreamParser(indIn, limit, tmpBuffers);
 
                 if ((tag & Asn1Tags.Application) != 0)
                 {