/// <summary>
/// Create a new instance of FieldMetaData with a given MemberInfo.
/// </summary>
/// <param name="outRef">Indicates the reference of the out object that hold this constraint.</param>
/// <param name="info"></param>
/// <remarks>
/// AttachedTag, Constraint will be set automatically by reflection.
/// </remarks>
protected Asn1ConstraintedFieldMetadata(Asn1Object outRef, MemberInfo info)
{
OutReference = outRef;
MemberInfo = info;
//Get AttachedTag
AttachedTag = null;
var attrs = MemberInfo.GetCustomAttributes(typeof(Asn1Tag), true);
if (attrs.Length != 0)
{
//Only the first tag is valid.
Asn1Tag tag = attrs[0] as Asn1Tag;
if (tag.TagType != Asn1TagType.Context && tag.TagType != Asn1TagType.Application)
{
throw new Asn1UserDefinedTypeInconsistent(ExceptionMessages.UserDefinedTypeInconsistent
+ " Only Context-Specific tag and Application tag are allowed.");
}
AttachedTag = tag;
}
//Get Constraint
Constraint = GetConstraints();
}
/// <summary>
/// Encodes a tag to the buffer.
/// </summary>
/// <param name="buffer"></param>
/// <param name="tag"></param>
/// <returns>The length of the encoding result.</returns>
/// <remarks>Override this method in a user-defined class only if the procedure is not applicable in some special scenarios.</remarks>
protected virtual int TagBerEncode(IAsn1BerEncodingBuffer buffer, Asn1Tag tag)
{
return Asn1StandardProcedure.TagBerEncode(buffer, tag);
}
/// <summary>
/// Decodes a tag from the buffer.
/// </summary>
/// <param name="buffer"></param>
/// <param name="tag"></param>
/// <returns>The number of the bytes consumed in the buffer to decode the tag.</returns>
/// <remarks>Override this method in a user-defined class only if the procedure is not applicable in some special scenarios.</remarks>
protected virtual int TagBerDecode(IAsn1DecodingBuffer buffer, out Asn1Tag tag)
{
return Asn1StandardProcedure.TagBerDecode(buffer, out tag);
}
/// <summary>
/// Encodes a tag to the buffer.
/// </summary>
/// <param name="buffer"></param>
/// <param name="tag"></param>
/// <returns>The length of the encoding result.</returns>
public static int TagBerEncode(IAsn1BerEncodingBuffer buffer, Asn1Tag tag)
{
//Ref. X.690: 8.1.2.2, there are four kinds of tags
byte prefix = 0;
switch (tag.TagType)
{
case Asn1TagType.Universal:
{
prefix = 0;//00
} break;
case Asn1TagType.Application:
{
prefix = 1;//01
} break;
case Asn1TagType.Context:
{
prefix = 2;//10
} break;
case Asn1TagType.Private:
{
prefix = 3;//11
//Ref. X.680: G.2.12.4
throw new Asn1UnreachableExcpetion(ExceptionMessages.Unreachable);
};
}
prefix <<= 6;
if (tag.EncodingWay == EncodingWay.Constructed)
{
prefix |= (1 << 5);//Set the sixth bit to 1 if it is encoded in constructed way. Ref. X.690: 8.1.2.3
}
if (tag.TagValue <= 30)//Use one byte to store the encoding result
//Ref. X.690: 8.1.2.3
{
prefix |= (byte)tag.TagValue;
buffer.WriteByte(prefix);
return 1;
}
else//Use more than one bytes to store.
{
//Ref. X.690: 8.1.2.4.3
throw new NotImplementedException("Case tag > 30 is not implemented. Check X.690: 8.1.2.4.3.");
}
}
/// <summary>
/// Decodes a tag from the buffer.
/// </summary>
/// <param name="buffer"></param>
/// <param name="tag"></param>
/// <returns>The number of the bytes consumed in the buffer to decode the tag.</returns>
public static int TagBerDecode(IAsn1DecodingBuffer buffer, out Asn1Tag tag)
{
byte prefix = buffer.ReadByte();
int firstTwoBits = (prefix >> 6);
Asn1TagType tagType = Asn1TagType.Private;
long tagValue;
switch (firstTwoBits)
{
case 0:
{
tagType = Asn1TagType.Universal;
} break;
case 1:
{
tagType = Asn1TagType.Application;
} break;
case 2:
{
tagType = Asn1TagType.Context;
} break;
case 3:
{
throw new NotImplementedException(ExceptionMessages.Unreachable);
};
}
tagValue = prefix & ((byte)(1 << 5) - 1);
if (tagValue <= 30)
{
tag = new Asn1Tag(tagType, tagValue);
if ((prefix & (1 << 5)) != 0)
{
tag.EncodingWay = EncodingWay.Constructed;
}
else
{
tag.EncodingWay = EncodingWay.Primitive;
}
return 1;
}
else
{
throw new NotImplementedException("Case tag > 30 is not implemented. Check X.690: 8.1.2.4.3.");
}
}
public override int BerEncode(IAsn1BerEncodingBuffer buffer, bool explicitTag = true)
{
int allLen = 0;
Asn1Tag contextTag;
switch (SelectedChoice)
{
case 0:
allLen += field0.BerEncodeWithoutUnisersalTag(buffer);
contextTag = new Asn1Tag(Asn1TagType.Context, 0) { EncodingWay = EncodingWay.Primitive };
allLen += TagBerEncode(buffer, contextTag);
break;
case 1:
allLen += field1.BerEncodeWithoutUnisersalTag(buffer);
contextTag = new Asn1Tag(Asn1TagType.Context, 3) { EncodingWay = EncodingWay.Constructed };
allLen += TagBerEncode(buffer, contextTag);
break;
case 2:
allLen += field2.BerEncodeWithoutUnisersalTag(buffer);
contextTag = new Asn1Tag(Asn1TagType.Context, 9) { EncodingWay = EncodingWay.Primitive };
allLen += TagBerEncode(buffer, contextTag);
break;
case 3:
allLen += field3.BerEncodeWithoutUnisersalTag(buffer);
contextTag = new Asn1Tag(Asn1TagType.Context, 10) { EncodingWay = EncodingWay.Primitive };
allLen += TagBerEncode(buffer, contextTag);
break;
case 4:
allLen += field4.BerEncodeWithoutUnisersalTag(buffer);
contextTag = new Asn1Tag(Asn1TagType.Context, 11) { EncodingWay = EncodingWay.Primitive };
allLen += TagBerEncode(buffer, contextTag);
break;
default:
throw new Asn1ConstraintsNotSatisfied(ExceptionMessages.InvalidChoiceIndex + " AuthenticationChoice");
}
return allLen;
}
