Merge bitcoin/bitcoin#28944: wallet, rpc: add anti-fee-sniping to send and sendall

aac0b6dd79 test: test sendall and send do anti-fee-sniping (ishaanam)
20802c7b65 wallet, rpc: add anti-fee-sniping to `send` and `sendall` (ishaanam)

Pull request description:

  Currently, `send` and `sendall` don't do anti-fee-sniping because they don't use `CreateTransaction`. This PR adds anti-fee-sniping to these RPCs by calling `DiscourageFeeSniping` from `FinishTransaction` when the user does not specify a locktime.

ACKs for top commit:
  achow101:
    ACK aac0b6dd79
  murchandamus:
    ACK aac0b6dd79
  glozow:
    ACK aac0b6dd79

Tree-SHA512: d4f1b43b5bda489bdba46b0af60e50bff0de604a35670e6ea6e1de2b539f16b3f68805492f51d6d2078d421b63432ca22a561a5721d1a37686f2e48284e1e646

test/functional/wallet_rescan_unconfirmed.py

@@ -53,7 +53,7 @@ class WalletRescanUnconfirmed(BitcoinTestFramework):
         # The only UTXO available to spend is tx_parent_to_reorg.
         assert_equal(len(w0_utxos), 1)
         assert_equal(w0_utxos[0]["txid"], tx_parent_to_reorg["txid"])
-        tx_child_unconfirmed_sweep = w0.sendall([ADDRESS_BCRT1_UNSPENDABLE])
+        tx_child_unconfirmed_sweep = w0.sendall(recipients=[ADDRESS_BCRT1_UNSPENDABLE], options={"locktime":0})
         assert tx_child_unconfirmed_sweep["txid"] in node.getrawmempool()
         node.syncwithvalidationinterfacequeue()
 

test/functional/wallet_send.py

@@ -144,7 +144,12 @@ class WalletSendTest(BitcoinTestFramework):
             return
 
         if locktime:
+            assert_equal(from_wallet.gettransaction(txid=res["txid"], verbose=True)["decoded"]["locktime"], locktime)
             return res
+        else:
+            if add_to_wallet:
+                decoded_tx = from_wallet.gettransaction(txid=res["txid"], verbose=True)["decoded"]
+                assert_greater_than(decoded_tx["locktime"], from_wallet.getblockcount() - 100)
 
         if expect_sign:
             assert_equal(res["complete"], True)

test/functional/wallet_sendall.py

@@ -6,6 +6,7 @@
 
 from decimal import Decimal, getcontext
 
+from test_framework.messages import SEQUENCE_FINAL
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal,
@@ -430,6 +431,26 @@ class SendallTest(BitcoinTestFramework):
 
         assert_greater_than(higher_parent_feerate_amount, lower_parent_feerate_amount)
 
+    @cleanup
+    def sendall_anti_fee_sniping(self):
+        self.log.info("Testing sendall does anti-fee-sniping when locktime is not specified")
+        self.add_utxos([10,11])
+        tx_from_wallet = self.test_sendall_success(sendall_args = [self.remainder_target])
+
+        assert_greater_than(tx_from_wallet["decoded"]["locktime"], tx_from_wallet["blockheight"] - 100)
+
+        self.log.info("Testing sendall does not do anti-fee-sniping when locktime is specified")
+        self.add_utxos([10,11])
+        txid = self.wallet.sendall(recipients=[self.remainder_target], options={"locktime":0})["txid"]
+        assert_equal(self.wallet.gettransaction(txid=txid, verbose=True)["decoded"]["locktime"], 0)
+
+        self.log.info("Testing sendall does not do anti-fee-sniping when even one of the sequences is final")
+        self.add_utxos([10, 11])
+        utxos = self.wallet.listunspent()
+        utxos[0]["sequence"] = SEQUENCE_FINAL
+        txid = self.wallet.sendall(recipients=[self.remainder_target], inputs=utxos)["txid"]
+        assert_equal(self.wallet.gettransaction(txid=txid, verbose=True)["decoded"]["locktime"], 0)
+
     # This tests needs to be the last one otherwise @cleanup will fail with "Transaction too large" error
     def sendall_fails_with_transaction_too_large(self):
         self.log.info("Test that sendall fails if resulting transaction is too large")
@@ -511,6 +532,9 @@ class SendallTest(BitcoinTestFramework):
         # Sendall only uses outputs with less than a given number of confirmation when using minconf
         self.sendall_with_maxconf()
 
+        # Sendall discourages fee-sniping when a locktime is not specified
+        self.sendall_anti_fee_sniping()
+
         # Sendall spends unconfirmed change
         self.sendall_spends_unconfirmed_change()