Merge bitcoin/bitcoin#25625: test: add test for decoding PSBT with per-input preimage types

71a751f6c3 test: add test for decoding PSBT with per-input preimage types (Sebastian Falbesoner)
faf43378e2 refactor: move helper `random_bytes` to util library (Sebastian Falbesoner)
fdc1ca3896 test: add constants for PSBT key types (BIP 174) (Sebastian Falbesoner)
1b035c03f9 refactor: move PSBT(Map) helpers from signet miner to test framework (Sebastian Falbesoner)
7c0dfec2dd refactor: move `from_binary` helper from signet miner to test framework (Sebastian Falbesoner)
597a4b35f6 scripted-diff: rename `FromBinary` helper to `from_binary` (signet miner) (Sebastian Falbesoner)

Pull request description:

  This PR adds missing test coverage for the `decodepsbt` RPC in the case that a PSBT with on of the per-input preimage types (`PSBT_IN_RIPEMD160`, `PSBT_IN_SHA256`, `PSBT_IN_HASH160`, `PSBT_IN_HASH256`; see [BIP 174](https://github.com/bitcoin/bips/blob/master/bip-0174.mediawiki#Specification)) is passed. As preparation, the first four commits move the already existing helpers for (de)serialization of PSBTs and PSBTMaps from the signet miner to the test framework (in a new module `psbt.py`), which should be quite useful for further tests to easily create PSBTs.

ACKs for top commit:
  achow101:
    ACK 71a751f6c3

Tree-SHA512: 04f2671612d94029da2ac8dc15ff93c4c8fcb73fe0b8cf5970509208564df1f5e32319b53ae998dd6e544d37637a9b75609f27a3685da51f603f6ed0555635fb

contrib/signet/miner

@@ -4,7 +4,6 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 import argparse
-import base64
 import json
 import logging
 import math
@@ -15,14 +14,13 @@ import sys
 import time
 import subprocess
 
-from io import BytesIO
-
 PATH_BASE_CONTRIB_SIGNET = os.path.abspath(os.path.dirname(os.path.realpath(__file__)))
 PATH_BASE_TEST_FUNCTIONAL = os.path.abspath(os.path.join(PATH_BASE_CONTRIB_SIGNET, "..", "..", "test", "functional"))
 sys.path.insert(0, PATH_BASE_TEST_FUNCTIONAL)
 
 from test_framework.blocktools import get_witness_script, script_BIP34_coinbase_height # noqa: E402
-from test_framework.messages import CBlock, CBlockHeader, COutPoint, CTransaction, CTxIn, CTxInWitness, CTxOut, from_hex, deser_string, ser_compact_size, ser_string, ser_uint256, tx_from_hex # noqa: E402
+from test_framework.messages import CBlock, CBlockHeader, COutPoint, CTransaction, CTxIn, CTxInWitness, CTxOut, from_binary, from_hex, ser_string, ser_uint256, tx_from_hex # noqa: E402
+from test_framework.psbt import PSBT, PSBTMap, PSBT_GLOBAL_UNSIGNED_TX, PSBT_IN_FINAL_SCRIPTSIG, PSBT_IN_FINAL_SCRIPTWITNESS, PSBT_IN_NON_WITNESS_UTXO, PSBT_IN_SIGHASH_TYPE # noqa: E402
 from test_framework.script import CScriptOp # noqa: E402
 
 logging.basicConfig(
@@ -34,89 +32,6 @@ SIGNET_HEADER = b"\xec\xc7\xda\xa2"
 PSBT_SIGNET_BLOCK = b"\xfc\x06signetb"    # proprietary PSBT global field holding the block being signed
 RE_MULTIMINER = re.compile("^(\d+)(-(\d+))?/(\d+)$")
 
-# #### some helpers that could go into test_framework
-
-# like from_hex, but without the hex part
-def FromBinary(cls, stream):
-    """deserialize a binary stream (or bytes object) into an object"""
-    # handle bytes object by turning it into a stream
-    was_bytes = isinstance(stream, bytes)
-    if was_bytes:
-        stream = BytesIO(stream)
-    obj = cls()
-    obj.deserialize(stream)
-    if was_bytes:
-        assert len(stream.read()) == 0
-    return obj
-
-class PSBTMap:
-    """Class for serializing and deserializing PSBT maps"""
-
-    def __init__(self, map=None):
-        self.map = map if map is not None else {}
-
-    def deserialize(self, f):
-        m = {}
-        while True:
-            k = deser_string(f)
-            if len(k) == 0:
-                break
-            v = deser_string(f)
-            if len(k) == 1:
-                k = k[0]
-            assert k not in m
-            m[k] = v
-        self.map = m
-
-    def serialize(self):
-        m = b""
-        for k,v in self.map.items():
-            if isinstance(k, int) and 0 <= k and k <= 255:
-                k = bytes([k])
-            m += ser_compact_size(len(k)) + k
-            m += ser_compact_size(len(v)) + v
-        m += b"\x00"
-        return m
-
-class PSBT:
-    """Class for serializing and deserializing PSBTs"""
-
-    def __init__(self):
-        self.g = PSBTMap()
-        self.i = []
-        self.o = []
-        self.tx = None
-
-    def deserialize(self, f):
-        assert f.read(5) == b"psbt\xff"
-        self.g = FromBinary(PSBTMap, f)
-        assert 0 in self.g.map
-        self.tx = FromBinary(CTransaction, self.g.map[0])
-        self.i = [FromBinary(PSBTMap, f) for _ in self.tx.vin]
-        self.o = [FromBinary(PSBTMap, f) for _ in self.tx.vout]
-        return self
-
-    def serialize(self):
-        assert isinstance(self.g, PSBTMap)
-        assert isinstance(self.i, list) and all(isinstance(x, PSBTMap) for x in self.i)
-        assert isinstance(self.o, list) and all(isinstance(x, PSBTMap) for x in self.o)
-        assert 0 in self.g.map
-        tx = FromBinary(CTransaction, self.g.map[0])
-        assert len(tx.vin) == len(self.i)
-        assert len(tx.vout) == len(self.o)
-
-        psbt = [x.serialize() for x in [self.g] + self.i + self.o]
-        return b"psbt\xff" + b"".join(psbt)
-
-    def to_base64(self):
-        return base64.b64encode(self.serialize()).decode("utf8")
-
-    @classmethod
-    def from_base64(cls, b64psbt):
-        return FromBinary(cls, base64.b64decode(b64psbt))
-
-# #####
-
 def create_coinbase(height, value, spk):
     cb = CTransaction()
     cb.vin = [CTxIn(COutPoint(0, 0xffffffff), script_BIP34_coinbase_height(height), 0xffffffff)]
@@ -159,11 +74,11 @@ def signet_txs(block, challenge):
 
 def do_createpsbt(block, signme, spendme):
     psbt = PSBT()
-    psbt.g = PSBTMap( {0: signme.serialize(),
+    psbt.g = PSBTMap( {PSBT_GLOBAL_UNSIGNED_TX: signme.serialize(),
                        PSBT_SIGNET_BLOCK: block.serialize()
                      } )
-    psbt.i = [ PSBTMap( {0: spendme.serialize(),
-                         3: bytes([1,0,0,0])})
+    psbt.i = [ PSBTMap( {PSBT_IN_NON_WITNESS_UTXO: spendme.serialize(),
+                         PSBT_IN_SIGHASH_TYPE: bytes([1,0,0,0])})
              ]
     psbt.o = [ PSBTMap() ]
     return psbt.to_base64()
@@ -175,10 +90,10 @@ def do_decode_psbt(b64psbt):
     assert len(psbt.tx.vout) == 1
     assert PSBT_SIGNET_BLOCK in psbt.g.map
 
-    scriptSig = psbt.i[0].map.get(7, b"")
-    scriptWitness = psbt.i[0].map.get(8, b"\x00")
+    scriptSig = psbt.i[0].map.get(PSBT_IN_FINAL_SCRIPTSIG, b"")
+    scriptWitness = psbt.i[0].map.get(PSBT_IN_FINAL_SCRIPTWITNESS, b"\x00")
 
-    return FromBinary(CBlock, psbt.g.map[PSBT_SIGNET_BLOCK]), ser_string(scriptSig) + scriptWitness
+    return from_binary(CBlock, psbt.g.map[PSBT_SIGNET_BLOCK]), ser_string(scriptSig) + scriptWitness
 
 def finish_block(block, signet_solution, grind_cmd):
     block.vtx[0].vout[-1].scriptPubKey += CScriptOp.encode_op_pushdata(SIGNET_HEADER + signet_solution)