support p2tr outputs in size estimation

jmbitcoin/jmbitcoin/secp256k1_transaction.py

@@ -88,6 +88,7 @@ def there_is_one_segwit_input(input_types: List[str]) -> bool:
     # since each may have a different size of witness; in
     # that case, the internal list in this list comprehension
     # will need updating.
+    # note that there is no support yet for paying *from* p2tr.
     return any(y in ["p2sh-p2wpkh", "p2wpkh", "p2wsh"] for y in input_types)
 
 def estimate_tx_size(ins: List[str], outs: List[str]) -> Union[int, Tuple[int]]:
@@ -123,21 +124,30 @@ def estimate_tx_size(ins: List[str], outs: List[str]) -> Union[int, Tuple[int]]:
     # script's redeemscript field in the witness, but for arbitrary scripts,
     # the witness portion could be any other size.
     # Hence, we may need to modify this later.
+    #
+    # Note that there is no support yet for spending *from* p2tr:
+    # we should fix this soon, since it is desirable to be able to support
+    # coinjoins with counterparties sending taproot, but note, JM coinjoins
+    # do not allow non-standard (usually v0 segwit) inputs, anyway.
     inmults = {"p2wsh": {"w": 1 + 72 + 43, "nw": 41},
                "p2wpkh": {"w": 108, "nw": 41},
                "p2sh-p2wpkh": {"w": 108, "nw": 64},
                "p2pkh": {"w": 0, "nw": 148}}
 
     # Notes: in outputs, there is only 1 'scripthash'
-    # type for either segwit/nonsegwit.
+    # type for either segwit/nonsegwit (hence "p2sh-p2wpkh"
+    # is a bit misleading, but is kept to the same as inputs,
+    # for simplicity. See notes on inputs above).
     # p2wsh has structure 8 bytes output, then:
     # x22,x00,x20,(32 byte hash), so 32 + 3 + 8
     # note also there is no need to distinguish witness
     # here, outputs are always entirely nonwitness.
+    # p2tr is also 32 byte hash with x01 instead of x00 version.
     outmults = {"p2wsh": 43,
                "p2wpkh": 31,
                "p2sh-p2wpkh": 32,
-               "p2pkh": 34}
+               "p2pkh": 34,
+               "p2tr": 43}
 
     # nVersion, nLockTime, nins, nouts:
     nwsize =  4 + 4 + 2

jmbitcoin/test/test_tx_signing.py

@@ -36,13 +36,14 @@ from math import ceil
      (["p2pkh"], ["p2pkh", "p2sh-p2wpkh"], 224),
      (["p2sh-p2wpkh"], ["p2sh-p2wpkh"], 134),
      (["p2wpkh"], ["p2wpkh"], 110),
+     (["p2wpkh"], ["p2wpkh", "p2tr"], 153),
      ])
 def test_tx_size_estimate(inaddrtypes, outaddrtypes, size_expected):
     # non-sw only inputs result in a single integer return,
     # segwit inputs return (witness size, non-witness size)
     x = btc.estimate_tx_size(inaddrtypes, outaddrtypes)
     if btc.there_is_one_segwit_input(inaddrtypes):
-        s = ceil((x[0] + x[1] * 4)/4.0)
+        s = ceil((x[0] + x[1] * 4) / 4.0)
     else:
         s = x
     assert s == size_expected

jmclient/jmclient/cryptoengine.py

@@ -16,7 +16,7 @@ from .configure import get_network, jm_single
 # make existing wallets unsable.
 TYPE_P2PKH, TYPE_P2SH_P2WPKH, TYPE_P2WPKH, TYPE_P2SH_M_N, TYPE_TIMELOCK_P2WSH, \
     TYPE_SEGWIT_WALLET_FIDELITY_BONDS, TYPE_WATCHONLY_FIDELITY_BONDS, \
-    TYPE_WATCHONLY_TIMELOCK_P2WSH, TYPE_WATCHONLY_P2WPKH, TYPE_P2WSH = range(10)
+    TYPE_WATCHONLY_TIMELOCK_P2WSH, TYPE_WATCHONLY_P2WPKH, TYPE_P2WSH, TYPE_P2TR = range(11)
 NET_MAINNET, NET_TESTNET, NET_SIGNET = range(3)
 NET_MAP = {'mainnet': NET_MAINNET, 'testnet': NET_TESTNET,
     'signet': NET_SIGNET}
@@ -52,6 +52,8 @@ def detect_script_type(script_str):
         return TYPE_P2WPKH
     elif script.is_witness_v0_scripthash():
         return TYPE_P2WSH
+    elif script.is_witness_v1_taproot():
+        return TYPE_P2TR
     raise EngineError("Unknown script type for script '{}'"
                       .format(bintohex(script_str)))
 
@@ -224,6 +226,12 @@ class BTCEngine(object):
         stype = detect_script_type(script)
         assert stype in ENGINES
         engine = ENGINES[stype]
+        # TODO though taproot is currently a returnable
+        # type from detect_script_type, there is not yet
+        # a corresponding ENGINE, thus a None return is possible.
+        # Callers recognize this as EngineError.
+        if engine is None:
+            raise EngineError
         pscript = engine.pubkey_to_script(pubkey)
         return script == pscript
 
@@ -457,5 +465,6 @@ ENGINES = {
     TYPE_TIMELOCK_P2WSH: BTC_Timelocked_P2WSH,
     TYPE_WATCHONLY_TIMELOCK_P2WSH: BTC_Watchonly_Timelocked_P2WSH,
     TYPE_WATCHONLY_P2WPKH: BTC_Watchonly_P2WPKH,
-    TYPE_SEGWIT_WALLET_FIDELITY_BONDS: BTC_P2WPKH
+    TYPE_SEGWIT_WALLET_FIDELITY_BONDS: BTC_P2WPKH,
+    TYPE_P2TR: None # TODO
 }

jmclient/jmclient/taker_utils.py

@@ -121,12 +121,14 @@ def direct_send(wallet_service, amount, mixdepth, destination, answeryes=False,
             # we don't recognize the destination script type,
             # so set it as the same as the change (which will usually
             # be the same as the spending wallet, but see above for custom)
+            # Notice that this is handled differently to the sweep case above,
+            # because we must use a list - there is more than one output
             outtype = change_type
         outtypes = [change_type, outtype]
         # not doing a sweep; we will have change.
         # 8 inputs to be conservative; note we cannot account for the possibility
         # of non-standard input types at this point.
-        initial_fee_est = estimate_tx_fee(8,2, txtype=txtype, outtype=outtypes)
+        initial_fee_est = estimate_tx_fee(8, 2, txtype=txtype, outtype=outtypes)
         utxos = wallet_service.select_utxos(mixdepth, amount + initial_fee_est,
                                             includeaddr=True)
         script_types = get_utxo_scripts(wallet_service.wallet, utxos)

jmclient/jmclient/wallet.py

@@ -27,8 +27,8 @@ from .support import select_gradual, select_greedy, select_greediest, \
     select, NotEnoughFundsException
 from .cryptoengine import TYPE_P2PKH, TYPE_P2SH_P2WPKH, TYPE_P2WSH,\
     TYPE_P2WPKH, TYPE_TIMELOCK_P2WSH, TYPE_SEGWIT_WALLET_FIDELITY_BONDS,\
-    TYPE_WATCHONLY_FIDELITY_BONDS, TYPE_WATCHONLY_TIMELOCK_P2WSH, TYPE_WATCHONLY_P2WPKH,\
-    ENGINES, detect_script_type, EngineError
+    TYPE_WATCHONLY_FIDELITY_BONDS, TYPE_WATCHONLY_TIMELOCK_P2WSH, \
+    TYPE_WATCHONLY_P2WPKH, TYPE_P2TR, ENGINES, detect_script_type, EngineError
 from .support import get_random_bytes
 from . import mn_encode, mn_decode
 import jmbitcoin as btc
@@ -92,7 +92,7 @@ def estimate_tx_fee(ins, outs, txtype='p2pkh', outtype=None, extra_bytes=0):
 
     # See docstring for explanation:
     if isinstance(txtype, str):
-        ins = [txtype]* ins
+        ins = [txtype] * ins
     else:
         assert isinstance(txtype, list)
         ins = txtype
@@ -505,6 +505,8 @@ class BaseWallet(object):
             return 'p2sh-p2wpkh'
         elif script_type == TYPE_P2WSH:
             return 'p2wsh'
+        elif script_type == TYPE_P2TR:
+            return 'p2tr'
         # should be unreachable; all possible returns
         # from detect_script_type are covered.
         assert False