Support output of PSBT instead of broadcast in direct_send

jmclient/jmclient/cli_options.py

@@ -519,6 +519,14 @@ def get_sendpayment_parser():
                       help='specify recipient IRC nick for a '
                       'p2ep style payment, for example:\n'
                       'J5Ehn3EieVZFtm4q ')
+    parser.add_option('--psbt',
+                      action='store_true',
+                      dest='with_psbt',
+                      default=False,
+                      help='output as psbt instead of '
+                      'broadcasting the transaction. '
+                      'Currently only works with direct '
+                      'send (-N 0).')
 
     add_common_options(parser)
     return parser

jmclient/jmclient/taker_utils.py

@@ -11,7 +11,8 @@ from .schedule import human_readable_schedule_entry, tweak_tumble_schedule,\
     schedule_to_text
 from .wallet import BaseWallet, estimate_tx_fee, compute_tx_locktime, \
     FidelityBondMixin
-from jmbitcoin import make_shuffled_tx, amount_to_str, mk_burn_script
+from jmbitcoin import make_shuffled_tx, amount_to_str, mk_burn_script,\
+                       PartiallySignedTransaction, CMutableTxOut
 from jmbase.support import EXIT_SUCCESS
 log = get_log()
 
@@ -22,7 +23,7 @@ Currently re-used by CLI script tumbler.py and joinmarket-qt
 
 def direct_send(wallet_service, amount, mixdepth, destination, answeryes=False,
                 accept_callback=None, info_callback=None,
-                return_transaction=False):
+                return_transaction=False, with_final_psbt=False):
     """Send coins directly from one mixdepth to one destination address;
     does not need IRC. Sweep as for normal sendpayment (set amount=0).
     If answeryes is True, callback/command line query is not performed.
@@ -39,8 +40,13 @@ def direct_send(wallet_service, amount, mixdepth, destination, answeryes=False,
     pushed), and returns nothing.
 
     This function returns:
-    The txid if transaction is pushed, False otherwise,
-    or the full CMutableTransaction if return_transaction is True.
+    1. False if there is any failure.
+    2. The txid if transaction is pushed, and return_transaction is False,
+       and with_final_psbt is False.
+    3. The full CMutableTransaction is return_transaction is True and
+       with_final_psbt is False.
+    4. The PSBT object if with_final_psbt is True, and in
+       this case the transaction is *NOT* broadcast.
     """
     #Sanity checks
     assert validate_address(destination)[0] or is_burn_destination(destination)
@@ -139,9 +145,26 @@ def direct_send(wallet_service, amount, mixdepth, destination, answeryes=False,
     tx = make_shuffled_tx(list(utxos.keys()), outs, 2, tx_locktime)
 
     inscripts = {}
+    spent_outs = []
     for i, txinp in enumerate(tx.vin):
         u = (txinp.prevout.hash[::-1], txinp.prevout.n)
         inscripts[i] = (utxos[u]["script"], utxos[u]["value"])
+        spent_outs.append(CMutableTxOut(utxos[u]["value"],
+                                        utxos[u]["script"]))
+    if with_final_psbt:
+        # here we have the PSBTWalletMixin do the signing stage
+        # for us:
+        new_psbt = wallet_service.create_psbt_from_tx(tx, spent_outs=spent_outs)
+        serialized_psbt, err = wallet_service.sign_psbt(new_psbt.serialize())
+        if err:
+            log.error("Failed to sign PSBT, quitting. Error message: " + err)
+            return False
+        new_psbt_signed = PartiallySignedTransaction.deserialize(serialized_psbt)
+        print("Completed PSBT created: ")
+        print(pformat(new_psbt_signed))
+        # TODO add more readable info here as for case below.
+        return new_psbt_signed
+    else:
         success, msg = wallet_service.sign_tx(tx, inscripts)
         if not success:
             log.error("Failed to sign transaction, quitting. Error msg: " + msg)
@@ -170,7 +193,6 @@ def direct_send(wallet_service, amount, mixdepth, destination, answeryes=False,
         txinfo = txid if not return_transaction else tx
         return txinfo
 
-
 def sign_tx(wallet_service, tx, utxos):
     stx = deserialize(tx)
     our_inputs = {}

scripts/sendpayment.py

@@ -190,7 +190,12 @@ def main():
                 .format(exp_tx_fees_ratio))
 
     if options.makercount == 0 and not options.p2ep:
-        direct_send(wallet_service, amount, mixdepth, destaddr, options.answeryes)
+        tx = direct_send(wallet_service, amount, mixdepth, destaddr,
+                         options.answeryes, with_final_psbt=options.with_psbt)
+        if options.with_psbt:
+            log.info("This PSBT is fully signed and can be sent externally for "
+                     "broadcasting:")
+            log.info(tx.to_base64())
         return
 
     if wallet.get_txtype() == 'p2pkh':