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using System;
using System.IO;
using Org.BouncyCastle.Bcpg.Sig;
using Org.BouncyCastle.Utilities;
using Org.BouncyCastle.Utilities.IO;
namespace Org.BouncyCastle.Bcpg
{
/**
* reader for signature sub-packets
*/
public class SignatureSubpacketsParser
{
private readonly Stream input;
public SignatureSubpacketsParser(
Stream input)
{
this.input = input;
}
public SignatureSubpacket ReadPacket()
{
int l = input.ReadByte();
if (l < 0)
return null;
int bodyLen = 0;
bool isLongLength = false;
if (l < 192)
{
bodyLen = l;
}
else if (l <= 223)
{
bodyLen = ((l - 192) << 8) + (input.ReadByte()) + 192;
}
else if (l == 255)
{
isLongLength = true;
bodyLen = (input.ReadByte() << 24) | (input.ReadByte() << 16)
| (input.ReadByte() << 8) | input.ReadByte();
}
else
{
throw new IOException("unexpected length header");
}
int tag = input.ReadByte();
if (tag < 0)
throw new EndOfStreamException("unexpected EOF reading signature sub packet");
if (bodyLen <= 0)
throw new EndOfStreamException("out of range data found in signature sub packet");
byte[] data = new byte[bodyLen - 1];
//
// this may seem a bit strange but it turns out some applications miscode the length
// in fixed length fields, so we check the length we do get, only throwing an exception if
// we really cannot continue
//
int bytesRead = Streams.ReadFully(input, data);
bool isCritical = ((tag & 0x80) != 0);
SignatureSubpacketTag type = (SignatureSubpacketTag)(tag & 0x7f);
if (bytesRead != data.Length)
{
switch (type)
{
case SignatureSubpacketTag.CreationTime:
data = CheckData(data, 4, bytesRead, "Signature Creation Time");
break;
case SignatureSubpacketTag.IssuerKeyId:
data = CheckData(data, 8, bytesRead, "Issuer");
break;
case SignatureSubpacketTag.KeyExpireTime:
data = CheckData(data, 4, bytesRead, "Signature Key Expiration Time");
break;
case SignatureSubpacketTag.ExpireTime:
data = CheckData(data, 4, bytesRead, "Signature Expiration Time");
break;
default:
throw new EndOfStreamException("truncated subpacket data.");
}
}
switch (type)
{
case SignatureSubpacketTag.CreationTime:
return new SignatureCreationTime(isCritical, isLongLength, data);
case SignatureSubpacketTag.KeyExpireTime:
return new KeyExpirationTime(isCritical, isLongLength, data);
case SignatureSubpacketTag.ExpireTime:
return new SignatureExpirationTime(isCritical, isLongLength, data);
case SignatureSubpacketTag.Revocable:
return new Revocable(isCritical, isLongLength, data);
case SignatureSubpacketTag.Exportable:
return new Exportable(isCritical, isLongLength, data);
case SignatureSubpacketTag.IssuerKeyId:
return new IssuerKeyId(isCritical, isLongLength, data);
case SignatureSubpacketTag.TrustSig:
return new TrustSignature(isCritical, isLongLength, data);
case SignatureSubpacketTag.PreferredCompressionAlgorithms:
case SignatureSubpacketTag.PreferredHashAlgorithms:
case SignatureSubpacketTag.PreferredSymmetricAlgorithms:
return new PreferredAlgorithms(type, isCritical, isLongLength, data);
case SignatureSubpacketTag.KeyFlags:
return new KeyFlags(isCritical, isLongLength, data);
case SignatureSubpacketTag.PrimaryUserId:
return new PrimaryUserId(isCritical, isLongLength, data);
case SignatureSubpacketTag.SignerUserId:
return new SignerUserId(isCritical, isLongLength, data);
case SignatureSubpacketTag.NotationData:
return new NotationData(isCritical, isLongLength, data);
case SignatureSubpacketTag.RevocationReason:
return new RevocationReason(isCritical, isLongLength, data);
case SignatureSubpacketTag.RevocationKey:
return new RevocationKey(isCritical, isLongLength, data);
}
return new SignatureSubpacket(type, isCritical, isLongLength, data);
}
private byte[] CheckData(byte[] data, int expected, int bytesRead, string name)
{
if (bytesRead != expected)
throw new EndOfStreamException("truncated " + name + " subpacket data.");
return Arrays.CopyOfRange(data, 0, expected);
}
}
}
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