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using System;
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
using System.Buffers.Binary;
#endif
using System.IO;
using Org.BouncyCastle.Utilities;
using Org.BouncyCastle.Utilities.IO;
namespace Org.BouncyCastle.Asn1
{
/**
* a general purpose ASN.1 decoder - note: this class differs from the
* others in that it returns null after it has read the last object in
* the stream. If an ASN.1 Null is encountered a Der/BER Null object is
* returned.
*/
public class Asn1InputStream
: FilterStream
{
private readonly int limit;
private readonly bool m_leaveOpen;
internal byte[][] tmpBuffers;
internal static int FindLimit(Stream input)
{
if (input is LimitedInputStream limited)
return limited.Limit;
if (input is Asn1InputStream asn1)
return asn1.limit;
if (input is MemoryStream memory)
return Convert.ToInt32(memory.Length - memory.Position);
return int.MaxValue;
}
/**
* 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 array containing ASN.1 encoded data.
*/
public Asn1InputStream(byte[] input)
: this(new MemoryStream(input, false), input.Length)
{
}
public Asn1InputStream(Stream input)
: this(input, FindLimit(input))
{
}
/**
* Create an ASN1InputStream where no DER object will be longer than limit.
*
* @param input stream containing ASN.1 encoded data.
* @param limit maximum size of a DER encoded object.
*/
public Asn1InputStream(Stream input, int limit)
: this(input, limit, false)
{
}
public Asn1InputStream(Stream input, int limit, bool leaveOpen)
: this(input, limit, leaveOpen, new byte[16][])
{
}
internal Asn1InputStream(Stream input, int limit, bool leaveOpen, byte[][] tmpBuffers)
: base(input)
{
if (!input.CanRead)
throw new ArgumentException("Expected stream to be readable", nameof(input));
this.limit = limit;
m_leaveOpen = leaveOpen;
this.tmpBuffers = tmpBuffers;
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
tmpBuffers = null;
}
if (m_leaveOpen)
{
base.Detach(disposing);
}
else
{
base.Dispose(disposing);
}
}
/**
* build an object given its tag and the number of bytes to construct it from.
*/
private Asn1Object BuildObject(int tagHdr, int tagNo, int length)
{
// TODO[asn1] Special-case zero length first?
DefiniteLengthInputStream defIn = new DefiniteLengthInputStream(s, length, limit);
if (0 == (tagHdr & Asn1Tags.Flags))
return CreatePrimitiveDerObject(tagNo, defIn, tmpBuffers);
int tagClass = tagHdr & Asn1Tags.Private;
if (0 != tagClass)
{
bool isConstructed = (tagHdr & Asn1Tags.Constructed) != 0;
return ReadTaggedObjectDL(tagClass, tagNo, isConstructed, defIn);
}
switch (tagNo)
{
case Asn1Tags.BitString:
return BuildConstructedBitString(ReadVector(defIn));
case Asn1Tags.OctetString:
return BuildConstructedOctetString(ReadVector(defIn));
case Asn1Tags.Sequence:
return DLSequence.FromVector(ReadVector(defIn));
case Asn1Tags.Set:
return DLSet.FromVector(ReadVector(defIn));
case Asn1Tags.External:
return DLSequence.FromVector(ReadVector(defIn)).ToAsn1External();
default:
throw new IOException("unknown tag " + tagNo + " encountered");
}
}
internal Asn1Object ReadTaggedObjectDL(int tagClass, int tagNo, bool constructed, DefiniteLengthInputStream defIn)
{
if (!constructed)
{
byte[] contentsOctets = defIn.ToArray();
return Asn1TaggedObject.CreatePrimitive(tagClass, tagNo, contentsOctets);
}
Asn1EncodableVector contentsElements = ReadVector(defIn);
return Asn1TaggedObject.CreateConstructedDL(tagClass, tagNo, contentsElements);
}
private Asn1EncodableVector ReadVector()
{
Asn1Object o = ReadObject();
if (null == o)
return new Asn1EncodableVector(0);
Asn1EncodableVector v = new Asn1EncodableVector();
do
{
v.Add(o);
}
while ((o = ReadObject()) != null);
return v;
}
private Asn1EncodableVector ReadVector(DefiniteLengthInputStream defIn)
{
int remaining = defIn.Remaining;
if (remaining < 1)
return new Asn1EncodableVector(0);
using (var sub = new Asn1InputStream(defIn, remaining, leaveOpen: true, tmpBuffers))
{
return sub.ReadVector();
}
}
public Asn1Object ReadObject()
{
int tagHdr = s.ReadByte();
if (tagHdr <= 0)
{
if (tagHdr == 0)
throw new IOException("unexpected end-of-contents marker");
return null;
}
int tagNo = ReadTagNumber(s, tagHdr);
int length = ReadLength(s, limit, false);
if (length >= 0)
{
// definite-length
try
{
return BuildObject(tagHdr, tagNo, length);
}
catch (ArgumentException e)
{
throw new Asn1Exception("corrupted stream detected", e);
}
}
// indefinite-length
if (0 == (tagHdr & Asn1Tags.Constructed))
throw new IOException("indefinite-length primitive encoding encountered");
IndefiniteLengthInputStream indIn = new IndefiniteLengthInputStream(s, limit);
Asn1StreamParser sp = new Asn1StreamParser(indIn, limit, tmpBuffers);
int tagClass = tagHdr & Asn1Tags.Private;
if (0 != tagClass)
return sp.LoadTaggedIL(tagClass, tagNo);
switch (tagNo)
{
case Asn1Tags.BitString:
return BerBitStringParser.Parse(sp);
case Asn1Tags.OctetString:
return BerOctetStringParser.Parse(sp);
case Asn1Tags.Sequence:
return BerSequenceParser.Parse(sp);
case Asn1Tags.Set:
return BerSetParser.Parse(sp);
case Asn1Tags.External:
// TODO[asn1] BerExternalParser
return DerExternalParser.Parse(sp);
default:
throw new IOException("unknown BER object encountered");
}
}
private DerBitString BuildConstructedBitString(Asn1EncodableVector contentsElements)
{
DerBitString[] bitStrings = new DerBitString[contentsElements.Count];
for (int i = 0; i != bitStrings.Length; i++)
{
DerBitString bitString = contentsElements[i] as DerBitString;
if (null == bitString)
throw new Asn1Exception("unknown object encountered in constructed BIT STRING: "
+ Platform.GetTypeName(contentsElements[i]));
bitStrings[i] = bitString;
}
return new DLBitString(BerBitString.FlattenBitStrings(bitStrings), false);
}
private Asn1OctetString BuildConstructedOctetString(Asn1EncodableVector contentsElements)
{
Asn1OctetString[] octetStrings = new Asn1OctetString[contentsElements.Count];
for (int i = 0; i != octetStrings.Length; i++)
{
Asn1OctetString octetString = contentsElements[i] as Asn1OctetString;
if (null == octetString)
throw new Asn1Exception("unknown object encountered in constructed OCTET STRING: "
+ Platform.GetTypeName(contentsElements[i]));
octetStrings[i] = octetString;
}
// Note: No DLOctetString available
return new DerOctetString(BerOctetString.FlattenOctetStrings(octetStrings));
}
internal static int ReadTagNumber(Stream s, int tagHdr)
{
int tagNo = tagHdr & 0x1f;
//
// with tagged object tag number is bottom 5 bits, or stored at the start of the content
//
if (tagNo == 0x1f)
{
int b = s.ReadByte();
if (b < 31)
{
if (b < 0)
throw new EndOfStreamException("EOF found inside tag value.");
throw new IOException("corrupted stream - high tag number < 31 found");
}
tagNo = b & 0x7f;
// X.690-0207 8.1.2.4.2
// "c) bits 7 to 1 of the first subsequent octet shall not all be zero."
if (0 == tagNo)
throw new IOException("corrupted stream - invalid high tag number found");
while ((b & 0x80) != 0)
{
if (((uint)tagNo >> 24) != 0U)
throw new IOException("Tag number more than 31 bits");
tagNo <<= 7;
b = s.ReadByte();
if (b < 0)
throw new EndOfStreamException("EOF found inside tag value.");
tagNo |= b & 0x7f;
}
}
return tagNo;
}
internal static int ReadLength(Stream s, int limit, bool isParsing)
{
int length = s.ReadByte();
if (0U == ((uint)length >> 7))
{
// definite-length short form
return length;
}
if (0x80 == length)
{
// indefinite-length
return -1;
}
if (length < 0)
{
throw new EndOfStreamException("EOF found when length expected");
}
if (0xFF == length)
{
throw new IOException("invalid long form definite-length 0xFF");
}
int octetsCount = length & 0x7F, octetsPos = 0;
length = 0;
do
{
int octet = s.ReadByte();
if (octet < 0)
throw new EndOfStreamException("EOF found reading length");
if (((uint)length >> 23) != 0U)
throw new IOException("long form definite-length more than 31 bits");
length = (length << 8) + octet;
}
while (++octetsPos < octetsCount);
if (length >= limit && !isParsing) // after all we must have read at least 1 byte
throw new IOException("corrupted stream - out of bounds length found: " + length + " >= " + limit);
return length;
}
private static bool GetBuffer(DefiniteLengthInputStream defIn, byte[][] tmpBuffers, out byte[] contents)
{
int len = defIn.Remaining;
if (len >= tmpBuffers.Length)
{
contents = defIn.ToArray();
return false;
}
byte[] buf = tmpBuffers[len];
if (buf == null)
{
buf = tmpBuffers[len] = new byte[len];
}
defIn.ReadAllIntoByteArray(buf);
contents = buf;
return true;
}
internal static Asn1Object CreatePrimitiveDerObject(int tagNo, DefiniteLengthInputStream defIn,
byte[][] tmpBuffers)
{
switch (tagNo)
{
case Asn1Tags.BmpString:
return CreateDerBmpString(defIn);
case Asn1Tags.Boolean:
{
GetBuffer(defIn, tmpBuffers, out var contents);
return DerBoolean.CreatePrimitive(contents);
}
case Asn1Tags.Enumerated:
{
bool usedBuffer = GetBuffer(defIn, tmpBuffers, out var contents);
return DerEnumerated.CreatePrimitive(contents, clone: usedBuffer);
}
case Asn1Tags.ObjectIdentifier:
{
bool usedBuffer = GetBuffer(defIn, tmpBuffers, out var contents);
return DerObjectIdentifier.CreatePrimitive(contents, clone: usedBuffer);
}
}
byte[] bytes = defIn.ToArray();
switch (tagNo)
{
case Asn1Tags.BitString:
return DerBitString.CreatePrimitive(bytes);
case Asn1Tags.GeneralizedTime:
return Asn1GeneralizedTime.CreatePrimitive(bytes);
case Asn1Tags.GeneralString:
return DerGeneralString.CreatePrimitive(bytes);
case Asn1Tags.GraphicString:
return DerGraphicString.CreatePrimitive(bytes);
case Asn1Tags.IA5String:
return DerIA5String.CreatePrimitive(bytes);
case Asn1Tags.Integer:
return DerInteger.CreatePrimitive(bytes);
case Asn1Tags.Null:
return Asn1Null.CreatePrimitive(bytes);
case Asn1Tags.NumericString:
return DerNumericString.CreatePrimitive(bytes);
case Asn1Tags.ObjectDescriptor:
return Asn1ObjectDescriptor.CreatePrimitive(bytes);
case Asn1Tags.OctetString:
return Asn1OctetString.CreatePrimitive(bytes);
case Asn1Tags.PrintableString:
return DerPrintableString.CreatePrimitive(bytes);
case Asn1Tags.RelativeOid:
return Asn1RelativeOid.CreatePrimitive(bytes, false);
case Asn1Tags.T61String:
return DerT61String.CreatePrimitive(bytes);
case Asn1Tags.UniversalString:
return DerUniversalString.CreatePrimitive(bytes);
case Asn1Tags.UtcTime:
return Asn1UtcTime.CreatePrimitive(bytes);
case Asn1Tags.Utf8String:
return DerUtf8String.CreatePrimitive(bytes);
case Asn1Tags.VideotexString:
return DerVideotexString.CreatePrimitive(bytes);
case Asn1Tags.VisibleString:
return DerVisibleString.CreatePrimitive(bytes);
case Asn1Tags.Time:
case Asn1Tags.Date:
case Asn1Tags.TimeOfDay:
case Asn1Tags.DateTime:
case Asn1Tags.Duration:
case Asn1Tags.ObjectIdentifierIri:
case Asn1Tags.RelativeOidIri:
throw new IOException("unsupported tag " + tagNo + " encountered");
default:
throw new IOException("unknown tag " + tagNo + " encountered");
}
}
private static DerBmpString CreateDerBmpString(DefiniteLengthInputStream defIn)
{
int remainingBytes = defIn.Remaining;
if (0 != (remainingBytes & 1))
throw new IOException("malformed BMPString encoding encountered");
int length = remainingBytes / 2;
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
return DerBmpString.CreatePrimitive(length, defIn, (str, defIn) =>
{
int stringPos = 0;
Span<byte> buf = stackalloc byte[8];
while (remainingBytes >= 8)
{
if (Streams.ReadFully(defIn, buf) != 8)
throw new EndOfStreamException("EOF encountered in middle of BMPString");
str[stringPos ] = (char)BinaryPrimitives.ReadUInt16BigEndian(buf[0..]);
str[stringPos + 1] = (char)BinaryPrimitives.ReadUInt16BigEndian(buf[2..]);
str[stringPos + 2] = (char)BinaryPrimitives.ReadUInt16BigEndian(buf[4..]);
str[stringPos + 3] = (char)BinaryPrimitives.ReadUInt16BigEndian(buf[6..]);
stringPos += 4;
remainingBytes -= 8;
}
if (remainingBytes > 0)
{
if (Streams.ReadFully(defIn, buf) != remainingBytes)
throw new EndOfStreamException("EOF encountered in middle of BMPString");
int bufPos = 0;
do
{
int b1 = buf[bufPos++] << 8;
int b2 = buf[bufPos++] & 0xFF;
str[stringPos++] = (char)(b1 | b2);
}
while (bufPos < remainingBytes);
}
if (0 != defIn.Remaining || str.Length != stringPos)
throw new InvalidOperationException();
});
#else
char[] str = new char[length];
int stringPos = 0;
byte[] buf = new byte[8];
while (remainingBytes >= 8)
{
if (Streams.ReadFully(defIn, buf, 0, 8) != 8)
throw new EndOfStreamException("EOF encountered in middle of BMPString");
str[stringPos ] = (char)((buf[0] << 8) | (buf[1] & 0xFF));
str[stringPos + 1] = (char)((buf[2] << 8) | (buf[3] & 0xFF));
str[stringPos + 2] = (char)((buf[4] << 8) | (buf[5] & 0xFF));
str[stringPos + 3] = (char)((buf[6] << 8) | (buf[7] & 0xFF));
stringPos += 4;
remainingBytes -= 8;
}
if (remainingBytes > 0)
{
if (Streams.ReadFully(defIn, buf, 0, remainingBytes) != remainingBytes)
throw new EndOfStreamException("EOF encountered in middle of BMPString");
int bufPos = 0;
do
{
int b1 = buf[bufPos++] << 8;
int b2 = buf[bufPos++] & 0xFF;
str[stringPos++] = (char)(b1 | b2);
}
while (bufPos < remainingBytes);
}
if (0 != defIn.Remaining || str.Length != stringPos)
throw new InvalidOperationException();
return DerBmpString.CreatePrimitive(str);
#endif
}
}
}
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