private static byte[] ComputeAddress(AbiSignature signature)
{
string[] argTypeNames = new string[signature.Types.Length];
for (int i = 0; i < signature.Types.Length; i++)
{
argTypeNames[i] = signature.Types[i].ToString();
}
string typeList = string.Join(",", argTypeNames);
string signatureString = $"{signature.Name}({typeList})";
Keccak signatureKeccak = Keccak.Compute(signatureString);
return(signatureKeccak.Bytes.Slice(0, 4));
}
public object[] Decode(AbiSignature signature, byte[] data)
{
string[] argTypeNames = new string[signature.Types.Length];
for (int i = 0; i < signature.Types.Length; i++)
{
argTypeNames[i] = signature.Types[i].ToString();
}
if (!Bytes.AreEqual(data.Slice(0, 4), ComputeAddress(signature)))
{
throw new AbiException(
$"Signature in encoded ABI data is not consistent with {ComputeSignature(signature.Name, signature.Types)}");
}
int position = 4;
object[] arguments = new object[signature.Types.Length];
int dynamicPosition = 0;
for (int i = 0; i < signature.Types.Length; i++)
{
AbiType type = signature.Types[i];
if (type.IsDynamic)
{
// TODO: do not have to decode this - can just jump 32 and check if first call and use dynamic position
(BigInteger offset, int nextPosition) = AbiType.UInt.DecodeUInt(data, position);
(arguments[i], dynamicPosition) = type.Decode(data, 4 + (int)offset);
position = nextPosition;
}
else
{
(arguments[i], position) = type.Decode(data, position);
}
}
if (Math.Max(position, dynamicPosition) != data.Length)
{
throw new AbiException($"Unexpected data at position {position}");
}
return(arguments);
}
public byte[] Encode(AbiSignature signature, params object[] arguments)
{
List <byte[]> dynamicParts = new List <byte[]>();
List <byte[]> headerParts = new List <byte[]>();
BigInteger currentOffset = arguments.Length * AbiType.UInt.LengthInBytes;
for (int i = 0; i < arguments.Length; i++)
{
AbiType type = signature.Types[i];
if (type.IsDynamic)
{
headerParts.Add(AbiType.UInt.Encode(currentOffset));
byte[] encoded = type.Encode(arguments[i]);
currentOffset += encoded.Length;
dynamicParts.Add(encoded);
}
else
{
headerParts.Add(type.Encode(arguments[i]));
}
}
byte[][] encodedParts = new byte[1 + headerParts.Count + dynamicParts.Count][];
encodedParts[0] = ComputeAddress(signature);
for (int i = 0; i < headerParts.Count; i++)
{
encodedParts[1 + i] = headerParts[i];
}
for (int i = 0; i < dynamicParts.Count; i++)
{
encodedParts[1 + headerParts.Count + i] = dynamicParts[i];
}
return(Bytes.Concat(encodedParts));
}