Merge #12676: Show "bip125-replaceable" flag, when retrieving mempool entries

870bd4c Update functional RBF test to check replaceable flag (dexX7)
820d31f Add "bip125-replaceable" flag to mempool RPCs (dexX7)

Pull request description:

  This pull request adds a flag "bip125-replaceable" to the mempool RPCs getrawmempool, getmempoolentry, getmempoolancestors and getmempooldescendants, which indicates whether an unconfirmed transaction might be replaced.

  Initially the flag was added to the raw transaction RPCs, but thanks to @conscott, it was moved to the mempool RPCs, which actually have access to the mempool.

  ~~This pull request adds a flag "bip125-replaceable" to the RPCs "getrawtransaction" and "decoderawtransaction", which indicates, whether a transaction signals BIP 125 replaceability.~~

  There was some discussion in #7817, whether showing replaceability in the UI could lead to the false assumption that transactions that don't signal BIP 125 are truely non-replaceable, but given that this PR tackles the raw transaction interface, which is a rather low level tool, I believe having this extra piece of information isn't bad.

Tree-SHA512: 1f5511957af2c20a9a6c79d80a335c3be37a2402dbf829c40cceaa01a24868eab81a9c1cdb0b3d77198fa3bb82799e3540a5c0ce7f35bbac80d73f7133ff7cbc

Author: laanwj

src/rpc/blockchain.cpp

@@ -18,6 +18,7 @@
 #include <key_io.h>
 #include <policy/feerate.h>
 #include <policy/policy.h>
+#include <policy/rbf.h>
 #include <primitives/transaction.h>
 #include <rpc/server.h>
 #include <script/descriptor.h>
@@ -379,7 +380,8 @@ static std::string EntryDescriptionString()
            "       ... ]\n"
            "    \"spentby\" : [           (array) unconfirmed transactions spending outputs from this transaction\n"
            "        \"transactionid\",    (string) child transaction id\n"
-           "       ... ]\n";
+           "       ... ]\n"
+           "    \"bip125-replaceable\" : true|false,  (boolean) Whether this transaction could be replaced due to BIP125 (replace-by-fee)\n";
 }
 
 static void entryToJSON(UniValue &info, const CTxMemPoolEntry &e) EXCLUSIVE_LOCKS_REQUIRED(::mempool.cs)
@@ -429,6 +431,17 @@ static void entryToJSON(UniValue &info, const CTxMemPoolEntry &e) EXCLUSIVE_LOCK
     }
 
     info.pushKV("spentby", spent);
+
+    // Add opt-in RBF status
+    bool rbfStatus = false;
+    RBFTransactionState rbfState = IsRBFOptIn(tx, mempool);
+    if (rbfState == RBFTransactionState::UNKNOWN) {
+        throw JSONRPCError(RPC_MISC_ERROR, "Transaction is not in mempool");
+    } else if (rbfState == RBFTransactionState::REPLACEABLE_BIP125) {
+        rbfStatus = true;
+    }
+
+    info.pushKV("bip125-replaceable", rbfStatus);
 }
 
 UniValue mempoolToJSON(bool fVerbose)

test/functional/feature_rbf.py

@@ -429,6 +429,9 @@ def test_opt_in(self):
         tx1a_hex = txToHex(tx1a)
         tx1a_txid = self.nodes[0].sendrawtransaction(tx1a_hex, True)
 
+        # This transaction isn't shown as replaceable
+        assert_equal(self.nodes[0].getmempoolentry(tx1a_txid)['bip125-replaceable'], False)
+
         # Shouldn't be able to double-spend
         tx1b = CTransaction()
         tx1b.vin = [CTxIn(tx0_outpoint, nSequence=0)]
@@ -469,7 +472,10 @@ def test_opt_in(self):
         tx3a.vout = [CTxOut(int(0.9*COIN), CScript([b'c'])), CTxOut(int(0.9*COIN), CScript([b'd']))]
         tx3a_hex = txToHex(tx3a)
 
-        self.nodes[0].sendrawtransaction(tx3a_hex, True)
+        tx3a_txid = self.nodes[0].sendrawtransaction(tx3a_hex, True)
+
+        # This transaction is shown as replaceable
+        assert_equal(self.nodes[0].getmempoolentry(tx3a_txid)['bip125-replaceable'], True)
 
         tx3b = CTransaction()
         tx3b.vin = [CTxIn(COutPoint(tx1a_txid, 0), nSequence=0)]