Add Decred transaction to and from bytes.

basicswap/interface/dcr/dcr.py

@@ -20,6 +20,7 @@ from basicswap.util.crypto import (
 )
 from basicswap.util.extkey import ExtKeyPair
 from basicswap.interface.dcr.rpc import make_rpc_func
+from .messages import CTransaction
 
 
 class DCRInterface(Secp256k1Interface):
@@ -119,3 +120,8 @@ class DCRInterface(Secp256k1Interface):
         ek_account = ek_coin.derive(0 | (1 << 31))
 
         return hash160(ek_account.encode_p())
+
+    def loadTx(self, tx_bytes: bytes) -> CTransaction:
+        tx = CTransaction()
+        tx.deserialize(tx_bytes)
+        return tx

basicswap/interface/dcr/messages.py

@@ -0,0 +1,158 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2024 tecnovert
+# Distributed under the MIT software license, see the accompanying
+# file LICENSE or http://www.opensource.org/licenses/mit-license.php.
+
+import copy
+from enum import IntEnum
+from basicswap.util.crypto import blake256
+from basicswap.util.integer import decode_varint, encode_varint
+
+
+class TxSerializeType(IntEnum):
+    Full = 0
+    NoWitness = 1
+    OnlyWitness = 2
+
+
+class COutpoint:
+    __slots__ = ('hash', 'n', 'tree')
+
+
+class CTxIn:
+    __slots__ = ('prevout', 'sequence',
+                 'value_in', 'block_height', 'block_index', 'signature_script')  # Witness
+
+
+class CTxOut:
+    __slots__ = ('value', 'version', 'script_pubkey')
+
+
+class CTransaction:
+    __slots__ = ('hash', 'version', 'vin', 'vout', 'locktime', 'expiry')
+
+    def __init__(self, tx=None):
+        if tx is None:
+            self.version = 1
+            self.vin = []
+            self.vout = []
+            self.locktime = 0
+            self.expiry = 0
+        else:
+            self.version = tx.version
+            self.vin = copy.deepcopy(tx.vin)
+            self.vout = copy.deepcopy(tx.vout)
+            self.locktime = tx.locktime
+            self.expiry = tx.expiry
+
+
+    def deserialize(self, data: bytes) -> None:
+
+        version = int.from_bytes(data[:4], 'little')
+        self.version = self.version & 0xffff
+        ser_type: int = version >> 16
+        o = 4
+
+        if ser_type == TxSerializeType.Full or ser_type == TxSerializeType.NoWitness:
+            num_txin, nb = decode_varint(data, o)
+            o += nb
+
+            for i in range(num_txin):
+                txi = CTxIn()
+                txi.prevout = COutpoint()
+                txi.prevout.hash = int.from_bytes(data[o:o + 32], 'little')
+                o += 32
+                txi.prevout.n = int.from_bytes(data[o:o + 4], 'little')
+                o += 4
+                txi.prevout.tree = data[o]
+                o += 1
+                txi.sequence = int.from_bytes(data[o:o + 4], 'little')
+                o += 4
+                self.vin.append(txi)
+
+            num_txout, nb = decode_varint(data, o)
+            o += nb
+
+            for i in range(num_txout):
+                txo = CTxOut()
+                txo.value = int.from_bytes(data[o:o + 8], 'little')
+                o += 8
+                txo.version = int.from_bytes(data[o:o + 2], 'little')
+                o += 2
+                script_bytes, nb = decode_varint(data, o)
+                o += nb
+                txo.script_pubkey = data[o:o + script_bytes]
+                o += script_bytes
+                self.vout.append(txo)
+
+            self.locktime = int.from_bytes(data[o:o + 4], 'little')
+            o += 4
+            self.expiry = int.from_bytes(data[o:o + 4], 'little')
+            o += 4
+
+        num_wit_scripts, nb = decode_varint(data, o)
+        o += nb
+
+        if ser_type == TxSerializeType.OnlyWitness:
+            self.vin = [CTxIn() for _ in range(num_wit_scripts)]
+        else:
+            if num_wit_scripts != len(self.vin):
+                raise ValueError('non equal witness and prefix txin quantities')
+
+        for i in range(num_wit_scripts):
+            txi = self.vin[i]
+            txi.value_in = int.from_bytes(data[o:o + 8], 'little')
+            o += 8
+            txi.block_height = int.from_bytes(data[o:o + 4], 'little')
+            o += 4
+            txi.block_index = int.from_bytes(data[o:o + 4], 'little')
+            o += 4
+            script_bytes, nb = decode_varint(data, o)
+            o += nb
+            txi.signature_script = data[o:o + script_bytes]
+            o += script_bytes
+
+    def serialize(self, ser_type=TxSerializeType.Full) -> bytes:
+        data = bytearray()
+        version = (self.version & 0xffff) | (ser_type << 16)
+        data += version.to_bytes(4, 'little')
+
+        if ser_type == TxSerializeType.Full or ser_type == TxSerializeType.NoWitness:
+            data += encode_varint(len(self.vin))
+            for txi in self.vin:
+                data += txi.prevout.hash.to_bytes(32, 'little')
+                data += txi.prevout.n.to_bytes(4, 'little')
+                data += txi.prevout.tree.to_bytes(1)
+                data += txi.sequence.to_bytes(4, 'little')
+
+            data += encode_varint(len(self.vout))
+            for txo in self.vout:
+                data += txo.value.to_bytes(8, 'little')
+                data += txo.version.to_bytes(2, 'little')
+                data += encode_varint(len(txo.script_pubkey))
+                data += txo.script_pubkey
+
+            data += self.locktime.to_bytes(4, 'little')
+            data += self.expiry.to_bytes(4, 'little')
+
+        if ser_type == TxSerializeType.Full or ser_type == TxSerializeType.OnlyWitness:
+            data += encode_varint(len(self.vin))
+            for txi in self.vin:
+                data += txi.value_in.to_bytes(8, 'little')
+                data += txi.block_height.to_bytes(4, 'little')
+                data += txi.block_index.to_bytes(4, 'little')
+                data += encode_varint(len(txi.signature_script))
+                data += txi.signature_script
+
+        return data
+
+    def TxHash(self) -> bytes:
+        return blake256(self.serialize(TxSerializeType.NoWitness))[::-1]
+
+    def TxHashWitness(self) -> bytes:
+        raise ValueError('todo')
+
+    def TxHashFull(self) -> bytes:
+        raise ValueError('todo')