public Asn1Tag(Asn1.Class asn1Class, int identifier, params Asn1Tag[] subTags)
: this(asn1Class, true, identifier)
{
foreach (Asn1Tag subTag in subTags)
{
AddSubTag(subTag);
}
}
/// <summary>
/// Read an ASN.1 tag identifier from a stream (as specified in X.690)
/// </summary>
/// <param name="stream">Stream to read from</param>
/// <param name="tagClass">Tag class of the tag</param>
/// <param name="constructed">Indicates if the tag is constructed = true (or primitive = false)</param>
/// <returns></returns>
private static int ReadIdentifier(Stream stream, out Asn1.Class tagClass, out bool constructed, out int fullIdentifier, out bool forceMultiByteIdentifier)
{
int identifier;
int b = stream.ReadByte();
if (b < 0)
{
throw new IOException("Unexpected end of ASN.1 data while reading identifier.");
}
// 8 7 | 6 | 5 4 3 2 1
// Class |P/C| Tag number
tagClass = (Asn1.Class)(b >> 6);
constructed = (b & 0x20) != 0;
fullIdentifier = 0;
if ((b & 0x1f) != 0x1f)
{
// Single byte identifier
identifier = b & 0x1f;
fullIdentifier = b;
forceMultiByteIdentifier = false;
}
else
{
// Multi byte identifier
identifier = 0;
fullIdentifier |= b;
// juse to be sure we force encoding this to multiple bytes to maintain the structue as much as we can
forceMultiByteIdentifier = true;
do
{
b = stream.ReadByte();
if (b < 0)
{
throw new IOException("Unexpected end of ASN.1 data while reading multi byte identifier.");
}
identifier <<= 7; // also happens first time, but that's ok, it's still 0
identifier |= b & 0x7F;
fullIdentifier <<= 8;
fullIdentifier |= b;
if (identifier == 0)
{
throw new IOException("Invalid ASN.1 identifier (0 while reading constructed identifier).");
}
} while ((b & 0x80) != 0);
}
return(identifier);
}
protected internal Asn1Tag(Asn1.Class asn1Class, bool constructed, int identifier)
: this()
{
Class = asn1Class;
Constructed = constructed;
Identifier = identifier;
// 8 7 | 6 | 5 4 3 2 1
// Class |P/C| Tag number
FullIdentifier = (((int)asn1Class) << 6) | (constructed ? 0x20 : 0x00) | (identifier & 0x1F);
}
public Asn1Tag(Asn1.Class asn1Class, int identifier, byte[] data)
: this(asn1Class, false, identifier)
{
Data = (byte[])data.Clone();
}
