Merge bitcoin/bitcoin#28414: wallet rpc: return final tx hex from walletprocesspsbt if complete

2e249b922762f19d6ae61edaad062f31bc2849f3 doc: add release note for PR #28414 (Matthew Zipkin)
4614332fc4514f63fcbe9e6de507f7bb9b7e87e9 test: remove unnecessary finalizepsbt rpc calls (ismaelsadeeq)
e3d484b603abff69c6ebfca5cfb78cf82743d090 wallet rpc: return final tx hex from walletprocesspsbt if complete (Matthew Zipkin)

Pull request description:

  See https://github.com/bitcoin/bitcoin/pull/28363#discussion_r1315753887

  `walletprocesspsbt` currently returns a base64-encoded PSBT and a boolean indicating if the tx is "complete". If it is complete, the base64 PSBT can be finalized with `finalizepsbt` which returns the hex-encoded transaction suitable for `sendrawtransaction`.

  With this patch, `walletprocesspsbt` return object will ALSO include the broadcast-able hex string if the tx is already final. This saves users the extra step of calling `finalizepsbt` assuming they have already inspected and approve the transaction from earlier steps.

ACKs for top commit:
  ismaelsadeeq:
    re ACK 2e249b922762f19d6ae61edaad062f31bc2849f3
  BrandonOdiwuor:
    re ACK 2e249b9
  Randy808:
    Tested ACK 2e249b922762f19d6ae61edaad062f31bc2849f3
  achow101:
    ACK 2e249b922762f19d6ae61edaad062f31bc2849f3
  ishaanam:
    ACK 2e249b922762f19d6ae61edaad062f31bc2849f3

Tree-SHA512: 229c1103265a9b4248f080935a7ad5607c3be3f9a096a9ab6554093b2cd8aa8b4d1fa55b1b97d3925ba208dbc3ccba4e4d37c40e1491db0d27ba3d9fe98f931e

8 files changed, 56 insertions, 46 deletions

diff --git a/doc/release-notes-28414.md b/doc/release-notes-28414.md
new file mode 100644
index 0000000000..7fca11f822
--- /dev/null
+++ b/doc/release-notes-28414.md
@@ -0,0 +1,5 @@
+RPC Wallet
+----------
+
+- RPC `walletprocesspsbt` return object now includes field `hex` (if the transaction
+is complete) containing the serialized transaction suitable for RPC `sendrawtransaction`. (#28414)
diff --git a/src/wallet/rpc/spend.cpp b/src/wallet/rpc/spend.cpp
index 0c2be26ddf..c4206e9897 100644
--- a/src/wallet/rpc/spend.cpp
+++ b/src/wallet/rpc/spend.cpp
@@ -1566,6 +1566,7 @@ RPCHelpMan walletprocesspsbt()
                     {
                         {RPCResult::Type::STR, "psbt", "The base64-encoded partially signed transaction"},
                         {RPCResult::Type::BOOL, "complete", "If the transaction has a complete set of signatures"},
+                        {RPCResult::Type::STR_HEX, "hex", /*optional=*/true, "The hex-encoded network transaction if complete"},
                     }
                 },
                 RPCExamples{
@@ -1609,6 +1610,14 @@ RPCHelpMan walletprocesspsbt()
     ssTx << psbtx;
     result.pushKV("psbt", EncodeBase64(ssTx.str()));
     result.pushKV("complete", complete);
+    if (complete) {
+        CMutableTransaction mtx;
+        // Returns true if complete, which we already think it is.
+        CHECK_NONFATAL(FinalizeAndExtractPSBT(psbtx, mtx));
+        CDataStream ssTx_final(SER_NETWORK, PROTOCOL_VERSION);
+        ssTx_final << mtx;
+        result.pushKV("hex", HexStr(ssTx_final));
+    }
 
     return result;
 },
diff --git a/test/functional/rpc_psbt.py b/test/functional/rpc_psbt.py
index b574a370d6..c01dc64df0 100755
--- a/test/functional/rpc_psbt.py
+++ b/test/functional/rpc_psbt.py
@@ -106,11 +106,11 @@ class PSBTTest(BitcoinTestFramework):
         assert "non_witness_utxo" in mining_node.decodepsbt(psbt_new.to_base64())["inputs"][0]
 
         # Have the offline node sign the PSBT (which will remove the non-witness UTXO)
-        signed_psbt = offline_node.walletprocesspsbt(psbt_new.to_base64())["psbt"]
-        assert not "non_witness_utxo" in mining_node.decodepsbt(signed_psbt)["inputs"][0]
+        signed_psbt = offline_node.walletprocesspsbt(psbt_new.to_base64())
+        assert not "non_witness_utxo" in mining_node.decodepsbt(signed_psbt["psbt"])["inputs"][0]
 
         # Make sure we can mine the resulting transaction
-        txid = mining_node.sendrawtransaction(mining_node.finalizepsbt(signed_psbt)["hex"])
+        txid = mining_node.sendrawtransaction(signed_psbt["hex"])
         self.generate(mining_node, nblocks=1, sync_fun=lambda: self.sync_all([online_node, mining_node]))
         assert_equal(online_node.gettxout(txid,0)["confirmations"], 1)
 
@@ -142,9 +142,8 @@ class PSBTTest(BitcoinTestFramework):
         utxo1 = tx1_inputs[0]
         assert_equal(unconfirmed_txid, utxo1['txid'])
 
-        signed_tx1 = wallet.walletprocesspsbt(psbtx1)['psbt']
-        final_tx1 = wallet.finalizepsbt(signed_tx1)['hex']
-        txid1 = self.nodes[0].sendrawtransaction(final_tx1)
+        signed_tx1 = wallet.walletprocesspsbt(psbtx1)
+        txid1 = self.nodes[0].sendrawtransaction(signed_tx1['hex'])
 
         mempool = self.nodes[0].getrawmempool()
         assert txid1 in mempool
@@ -157,9 +156,8 @@ class PSBTTest(BitcoinTestFramework):
 
         self.log.info("Fail to broadcast a new PSBT with maxconf 0 due to BIP125 rules to verify it actually chose unconfirmed outputs")
         psbt_invalid = wallet.walletcreatefundedpsbt([{'txid': utxo1['txid'], 'vout': utxo1['vout']}], {target_address: 1}, 0, {'add_inputs': True, 'maxconf': 0, 'fee_rate': 10})['psbt']
-        signed_invalid = wallet.walletprocesspsbt(psbt_invalid)['psbt']
-        final_invalid = wallet.finalizepsbt(signed_invalid)['hex']
-        assert_raises_rpc_error(-26, "bad-txns-spends-conflicting-tx", self.nodes[0].sendrawtransaction, final_invalid)
+        signed_invalid = wallet.walletprocesspsbt(psbt_invalid)
+        assert_raises_rpc_error(-26, "bad-txns-spends-conflicting-tx", self.nodes[0].sendrawtransaction, signed_invalid['hex'])
 
         self.log.info("Craft a replacement adding inputs with highest confs possible")
         psbtx2 = wallet.walletcreatefundedpsbt([{'txid': utxo1['txid'], 'vout': utxo1['vout']}], {target_address: 1}, 0, {'add_inputs': True, 'minconf': 2, 'fee_rate': 10})['psbt']
@@ -169,9 +167,8 @@ class PSBTTest(BitcoinTestFramework):
             if vin['txid'] != unconfirmed_txid:
                 assert_greater_than_or_equal(self.nodes[0].gettxout(vin['txid'], vin['vout'])['confirmations'], 2)
 
-        signed_tx2 = wallet.walletprocesspsbt(psbtx2)['psbt']
-        final_tx2 = wallet.finalizepsbt(signed_tx2)['hex']
-        txid2 = self.nodes[0].sendrawtransaction(final_tx2)
+        signed_tx2 = wallet.walletprocesspsbt(psbtx2)
+        txid2 = self.nodes[0].sendrawtransaction(signed_tx2['hex'])
 
         mempool = self.nodes[0].getrawmempool()
         assert txid1 not in mempool
@@ -217,12 +214,21 @@ class PSBTTest(BitcoinTestFramework):
 
         self.nodes[0].walletpassphrase(passphrase="password", timeout=1000000)
 
-        # Sign the transaction and send
-        signed_tx = self.nodes[0].walletprocesspsbt(psbt=psbtx, finalize=False)['psbt']
-        finalized_tx = self.nodes[0].walletprocesspsbt(psbt=psbtx, finalize=True)['psbt']
-        assert signed_tx != finalized_tx
-        final_tx = self.nodes[0].finalizepsbt(signed_tx)['hex']
-        self.nodes[0].sendrawtransaction(final_tx)
+        # Sign the transaction but don't finalize
+        processed_psbt = self.nodes[0].walletprocesspsbt(psbt=psbtx, finalize=False)
+        assert "hex" not in processed_psbt
+        signed_psbt = processed_psbt['psbt']
+
+        # Finalize and send
+        finalized_hex = self.nodes[0].finalizepsbt(signed_psbt)['hex']
+        self.nodes[0].sendrawtransaction(finalized_hex)
+
+        # Alternative method: sign AND finalize in one command
+        processed_finalized_psbt = self.nodes[0].walletprocesspsbt(psbt=psbtx, finalize=True)
+        finalized_psbt = processed_finalized_psbt['psbt']
+        finalized_psbt_hex = processed_finalized_psbt['hex']
+        assert signed_psbt != finalized_psbt
+        assert finalized_psbt_hex == finalized_hex
 
         # Manually selected inputs can be locked:
         assert_equal(len(self.nodes[0].listlockunspent()), 0)
@@ -296,7 +302,7 @@ class PSBTTest(BitcoinTestFramework):
         # Check decodepsbt fee calculation (input values shall only be counted once per UTXO)
         assert_equal(decoded['fee'], created_psbt['fee'])
         assert_equal(walletprocesspsbt_out['complete'], True)
-        self.nodes[1].sendrawtransaction(self.nodes[1].finalizepsbt(walletprocesspsbt_out['psbt'])['hex'])
+        self.nodes[1].sendrawtransaction(walletprocesspsbt_out['hex'])
 
         self.log.info("Test walletcreatefundedpsbt fee rate of 10000 sat/vB and 0.1 BTC/kvB produces a total fee at or slightly below -maxtxfee (~0.05290000)")
         res1 = self.nodes[1].walletcreatefundedpsbt(inputs, outputs, 0, {"fee_rate": 10000, "add_inputs": True})
@@ -387,7 +393,7 @@ class PSBTTest(BitcoinTestFramework):
         # partially sign with node 2. This should be complete and sendable
         walletprocesspsbt_out = self.nodes[2].walletprocesspsbt(psbtx)
         assert_equal(walletprocesspsbt_out['complete'], True)
-        self.nodes[2].sendrawtransaction(self.nodes[2].finalizepsbt(walletprocesspsbt_out['psbt'])['hex'])
+        self.nodes[2].sendrawtransaction(walletprocesspsbt_out['hex'])
 
         # check that walletprocesspsbt fails to decode a non-psbt
         rawtx = self.nodes[1].createrawtransaction([{"txid":txid,"vout":p2wpkh_pos}], {self.nodes[1].getnewaddress():9.99})
@@ -739,14 +745,13 @@ class PSBTTest(BitcoinTestFramework):
         assert not signed['complete']
         signed = self.nodes[0].walletprocesspsbt(signed['psbt'])
         assert signed['complete']
-        self.nodes[0].finalizepsbt(signed['psbt'])
 
         psbt = wallet.walletcreatefundedpsbt([ext_utxo], {self.nodes[0].getnewaddress(): 15}, 0, {"add_inputs": True, "solving_data":{"descriptors": [desc]}})
         signed = wallet.walletprocesspsbt(psbt['psbt'])
         assert not signed['complete']
         signed = self.nodes[0].walletprocesspsbt(signed['psbt'])
         assert signed['complete']
-        final = self.nodes[0].finalizepsbt(signed['psbt'], False)
+        final = signed['hex']
 
         dec = self.nodes[0].decodepsbt(signed["psbt"])
         for i, txin in enumerate(dec["tx"]["vin"]):
@@ -781,8 +786,8 @@ class PSBTTest(BitcoinTestFramework):
         )
         signed = wallet.walletprocesspsbt(psbt["psbt"])
         signed = self.nodes[0].walletprocesspsbt(signed["psbt"])
-        final = self.nodes[0].finalizepsbt(signed["psbt"])
-        assert self.nodes[0].testmempoolaccept([final["hex"]])[0]["allowed"]
+        final = signed["hex"]
+        assert self.nodes[0].testmempoolaccept([final])[0]["allowed"]
         # Reducing the weight should have a lower fee
         psbt2 = wallet.walletcreatefundedpsbt(
             inputs=[{"txid": ext_utxo["txid"], "vout": ext_utxo["vout"], "weight": low_input_weight}],
@@ -837,8 +842,8 @@ class PSBTTest(BitcoinTestFramework):
         self.nodes[0].importprivkey(privkey)
 
         psbt = watchonly.sendall([wallet.getnewaddress()])["psbt"]
-        psbt = self.nodes[0].walletprocesspsbt(psbt)["psbt"]
-        self.nodes[0].sendrawtransaction(self.nodes[0].finalizepsbt(psbt)["hex"])
+        signed_tx = self.nodes[0].walletprocesspsbt(psbt)
+        self.nodes[0].sendrawtransaction(signed_tx["hex"])
 
         # Same test but for taproot
         if self.options.descriptors:
@@ -853,8 +858,8 @@ class PSBTTest(BitcoinTestFramework):
             self.nodes[0].importdescriptors([{"desc": descsum_create("tr({})".format(privkey)), "timestamp":"now"}])
 
             psbt = watchonly.sendall([wallet.getnewaddress(), addr])["psbt"]
-            psbt = self.nodes[0].walletprocesspsbt(psbt)["psbt"]
-            txid = self.nodes[0].sendrawtransaction(self.nodes[0].finalizepsbt(psbt)["hex"])
+            processed_psbt = self.nodes[0].walletprocesspsbt(psbt)
+            txid = self.nodes[0].sendrawtransaction(processed_psbt["hex"])
             vout = find_vout_for_address(self.nodes[0], txid, addr)
 
             # Make sure tap tree is in psbt
@@ -871,7 +876,7 @@ class PSBTTest(BitcoinTestFramework):
             vout = find_vout_for_address(self.nodes[0], txid, addr)
             psbt = self.nodes[0].createpsbt([{"txid": txid, "vout": vout}], [{self.nodes[0].getnewaddress(): 0.9999}])
             signed = self.nodes[0].walletprocesspsbt(psbt)
-            rawtx = self.nodes[0].finalizepsbt(signed["psbt"])["hex"]
+            rawtx = signed["hex"]
             self.nodes[0].sendrawtransaction(rawtx)
             self.generate(self.nodes[0], 1)
 
diff --git a/test/functional/wallet_bumpfee.py b/test/functional/wallet_bumpfee.py
index e69c1829ca..c66f279e88 100755
--- a/test/functional/wallet_bumpfee.py
+++ b/test/functional/wallet_bumpfee.py
@@ -403,8 +403,7 @@ def test_notmine_bumpfee(self, rbf_node, peer_node, dest_address):
     def finish_psbtbumpfee(psbt):
         psbt = rbf_node.walletprocesspsbt(psbt)
         psbt = peer_node.walletprocesspsbt(psbt["psbt"])
-        final = rbf_node.finalizepsbt(psbt["psbt"])
-        res = rbf_node.testmempoolaccept([final["hex"]])
+        res = rbf_node.testmempoolaccept([psbt["hex"]])
         assert res[0]["allowed"]
         assert_greater_than(res[0]["fees"]["base"], old_fee)
 
@@ -638,8 +637,7 @@ def test_watchonly_psbt(self, peer_node, rbf_node, dest_address):
     psbt = watcher.walletcreatefundedpsbt([watcher.listunspent()[0]], {dest_address: 0.0005}, 0,
             {"fee_rate": 1, "add_inputs": False}, True)['psbt']
     psbt_signed = signer.walletprocesspsbt(psbt=psbt, sign=True, sighashtype="ALL", bip32derivs=True)
-    psbt_final = watcher.finalizepsbt(psbt_signed["psbt"])
-    original_txid = watcher.sendrawtransaction(psbt_final["hex"])
+    original_txid = watcher.sendrawtransaction(psbt_signed["hex"])
     assert_equal(len(watcher.decodepsbt(psbt)["tx"]["vin"]), 1)
 
     # bumpfee can't be used on watchonly wallets
@@ -654,11 +652,10 @@ def test_watchonly_psbt(self, peer_node, rbf_node, dest_address):
 
     # Sign bumped transaction
     bumped_psbt_signed = signer.walletprocesspsbt(psbt=bumped_psbt["psbt"], sign=True, sighashtype="ALL", bip32derivs=True)
-    bumped_psbt_final = watcher.finalizepsbt(bumped_psbt_signed["psbt"])
-    assert bumped_psbt_final["complete"]
+    assert bumped_psbt_signed["complete"]
 
     # Broadcast bumped transaction
-    bumped_txid = watcher.sendrawtransaction(bumped_psbt_final["hex"])
+    bumped_txid = watcher.sendrawtransaction(bumped_psbt_signed["hex"])
     assert bumped_txid in rbf_node.getrawmempool()
     assert original_txid not in rbf_node.getrawmempool()
 
diff --git a/test/functional/wallet_fundrawtransaction.py b/test/functional/wallet_fundrawtransaction.py
index fa4f009f34..b1829f42af 100755
--- a/test/functional/wallet_fundrawtransaction.py
+++ b/test/functional/wallet_fundrawtransaction.py
@@ -556,8 +556,7 @@ class RawTransactionsTest(BitcoinTestFramework):
         funded_psbt = wmulti.walletcreatefundedpsbt(inputs=inputs, outputs=outputs, changeAddress=w2.getrawchangeaddress())['psbt']
 
         signed_psbt = w2.walletprocesspsbt(funded_psbt)
-        final_psbt = w2.finalizepsbt(signed_psbt['psbt'])
-        self.nodes[2].sendrawtransaction(final_psbt['hex'])
+        self.nodes[2].sendrawtransaction(signed_psbt['hex'])
         self.generate(self.nodes[2], 1)
 
         # Make sure funds are received at node1.
diff --git a/test/functional/wallet_multisig_descriptor_psbt.py b/test/functional/wallet_multisig_descriptor_psbt.py
index 28bee1911e..68bf45f7e3 100755
--- a/test/functional/wallet_multisig_descriptor_psbt.py
+++ b/test/functional/wallet_multisig_descriptor_psbt.py
@@ -150,8 +150,7 @@ class WalletMultisigDescriptorPSBTTest(BitcoinTestFramework):
             signing_wallet = participants["signers"][m]
             psbt = signing_wallet.walletprocesspsbt(psbt["psbt"])
             assert_equal(psbt["complete"], m == self.M - 1)
-        finalized = coordinator_wallet.finalizepsbt(psbt["psbt"])
-        coordinator_wallet.sendrawtransaction(finalized["hex"])
+        coordinator_wallet.sendrawtransaction(psbt["hex"])
 
         self.log.info("Check that balances are correct after the transaction has been included in a block.")
         self.generate(self.nodes[0], 1)
diff --git a/test/functional/wallet_send.py b/test/functional/wallet_send.py
index 4728f53be7..6ce2a56bfc 100755
--- a/test/functional/wallet_send.py
+++ b/test/functional/wallet_send.py
@@ -530,13 +530,11 @@ class WalletSendTest(BitcoinTestFramework):
         signed = ext_wallet.walletprocesspsbt(res["psbt"])
         signed = ext_fund.walletprocesspsbt(res["psbt"])
         assert signed["complete"]
-        self.nodes[0].finalizepsbt(signed["psbt"])
 
         res = self.test_send(from_wallet=ext_wallet, to_wallet=self.nodes[0], amount=15, inputs=[ext_utxo], add_inputs=True, psbt=True, include_watching=True, solving_data={"descriptors": [desc]})
         signed = ext_wallet.walletprocesspsbt(res["psbt"])
         signed = ext_fund.walletprocesspsbt(res["psbt"])
         assert signed["complete"]
-        self.nodes[0].finalizepsbt(signed["psbt"])
 
         dec = self.nodes[0].decodepsbt(signed["psbt"])
         for i, txin in enumerate(dec["tx"]["vin"]):
@@ -574,8 +572,7 @@ class WalletSendTest(BitcoinTestFramework):
         signed = ext_wallet.walletprocesspsbt(res["psbt"])
         signed = ext_fund.walletprocesspsbt(res["psbt"])
         assert signed["complete"]
-        tx = self.nodes[0].finalizepsbt(signed["psbt"])
-        testres = self.nodes[0].testmempoolaccept([tx["hex"]])[0]
+        testres = self.nodes[0].testmempoolaccept([signed["hex"]])[0]
         assert_equal(testres["allowed"], True)
         assert_fee_amount(testres["fees"]["base"], testres["vsize"], Decimal(0.0001))
 
diff --git a/test/functional/wallet_signer.py b/test/functional/wallet_signer.py
index 2735ec1706..32a1887153 100755
--- a/test/functional/wallet_signer.py
+++ b/test/functional/wallet_signer.py
@@ -169,8 +169,7 @@ class WalletSignerTest(BitcoinTestFramework):
         dest = self.nodes[0].getnewaddress(address_type='bech32')
         mock_psbt = mock_wallet.walletcreatefundedpsbt([], {dest:0.5}, 0, {'replaceable': True}, True)['psbt']
         mock_psbt_signed = mock_wallet.walletprocesspsbt(psbt=mock_psbt, sign=True, sighashtype="ALL", bip32derivs=True)
-        mock_psbt_final = mock_wallet.finalizepsbt(mock_psbt_signed["psbt"])
-        mock_tx = mock_psbt_final["hex"]
+        mock_tx = mock_psbt_signed["hex"]
         assert mock_wallet.testmempoolaccept([mock_tx])[0]["allowed"]
 
         # # Create a new wallet and populate with specific public keys, in order