Merge bitcoin/bitcoin#26084: sendall: check if the maxtxfee has been exceeded

6f8e3818af sendall: check if the maxtxfee has been exceeded (ishaanam)

Pull request description:

  Previously the `sendall` RPC didn't check whether the fees of the transaction it creates exceed the set `maxtxfee`. This PR adds this check to `sendall` and a test case for it.

ACKs for top commit:
  achow101:
    ACK 6f8e3818af
  Xekyo:
    ACK 6f8e3818af
  glozow:
    Concept ACK 6f8e3818af. The high feerate is unlikely but sendall should respect the existing wallet options.

Tree-SHA512: 6ef0961937091293d49be16f17e4451cff3159d901c0c7c6e508883999dfe0c20ed4d7126bf74bfea8150d4c1eef961a45f0c28ef64562e6cb817fede2319f1a

src/wallet/rpc/spend.cpp

@@ -1402,6 +1402,10 @@ RPCHelpMan sendall()
             const CAmount fee_from_size{fee_rate.GetFee(tx_size.vsize)};
             const CAmount effective_value{total_input_value - fee_from_size};
 
+            if (fee_from_size > pwallet->m_default_max_tx_fee) {
+                throw JSONRPCError(RPC_WALLET_ERROR, TransactionErrorString(TransactionError::MAX_FEE_EXCEEDED).original);
+            }
+
             if (effective_value <= 0) {
                 if (send_max) {
                     throw JSONRPCError(RPC_WALLET_INSUFFICIENT_FUNDS, "Total value of UTXO pool too low to pay for transaction, try using lower feerate.");

test/functional/wallet_sendall.py

@@ -264,6 +264,18 @@ class SendallTest(BitcoinTestFramework):
             recipients=[self.remainder_target],
             options={"inputs": [utxo], "send_max": True})
 
+    @cleanup
+    def sendall_fails_on_high_fee(self):
+        self.log.info("Test sendall fails if the transaction fee exceeds the maxtxfee")
+        self.add_utxos([21])
+
+        assert_raises_rpc_error(
+                -4,
+                "Fee exceeds maximum configured by user",
+                self.wallet.sendall,
+                recipients=[self.remainder_target],
+                fee_rate=100000)
+
     def run_test(self):
         self.nodes[0].createwallet("activewallet")
         self.wallet = self.nodes[0].get_wallet_rpc("activewallet")
@@ -312,5 +324,8 @@ class SendallTest(BitcoinTestFramework):
         # Sendall fails when using send_max while specifying inputs
         self.sendall_fails_on_specific_inputs_with_send_max()
 
+        # Sendall fails when providing a fee that is too high
+        self.sendall_fails_on_high_fee()
+
 if __name__ == '__main__':
     SendallTest().main()