[wallet] abort when attempting to fund a transaction above maxtxfee

FundTransaction calls GetMinimumFee which, when the fee rate is absurdly high, quietly reduced the fee to -maxtxfee. Becaue an absurdly high fee rate is usually the result of a fat finger, aborting seems safer behavior.

Github-Pull: #16257
Rebased-From: 806b0052c3b45415862f74f20ba5f389e5b673de

2 files changed, 19 insertions, 1 deletions

diff --git a/test/functional/rpc_fundrawtransaction.py b/test/functional/rpc_fundrawtransaction.py
index 0c61e9ab62..019a9d4012 100755
--- a/test/functional/rpc_fundrawtransaction.py
+++ b/test/functional/rpc_fundrawtransaction.py
@@ -662,6 +662,7 @@ class RawTransactionsTest(BitcoinTestFramework):
         result = self.nodes[3].fundrawtransaction(rawtx) # uses min_relay_tx_fee (set by settxfee)
         result2 = self.nodes[3].fundrawtransaction(rawtx, {"feeRate": 2*min_relay_tx_fee})
         result3 = self.nodes[3].fundrawtransaction(rawtx, {"feeRate": 10*min_relay_tx_fee})
+        assert_raises_rpc_error(-4, "Fee exceeds maximum configured by -maxtxfee", self.nodes[3].fundrawtransaction, rawtx, {"feeRate": 1})
         result_fee_rate = result['fee'] * 1000 / count_bytes(result['hex'])
         assert_fee_amount(result2['fee'], count_bytes(result2['hex']), 2 * result_fee_rate)
         assert_fee_amount(result3['fee'], count_bytes(result3['hex']), 10 * result_fee_rate)
diff --git a/test/functional/rpc_psbt.py b/test/functional/rpc_psbt.py
index ef895dd13a..24ac14162c 100755
--- a/test/functional/rpc_psbt.py
+++ b/test/functional/rpc_psbt.py
@@ -6,7 +6,15 @@
 """
 
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.util import assert_equal, assert_raises_rpc_error, find_output, disconnect_nodes, connect_nodes_bi, sync_blocks
+from test_framework.util import (
+    assert_equal,
+    assert_greater_than,
+    assert_raises_rpc_error,
+    connect_nodes_bi,
+    disconnect_nodes,
+    find_output,
+    sync_blocks,
+)
 
 import json
 import os
@@ -122,6 +130,15 @@ class PSBTTest(BitcoinTestFramework):
         assert_equal(walletprocesspsbt_out['complete'], True)
         self.nodes[1].sendrawtransaction(self.nodes[1].finalizepsbt(walletprocesspsbt_out['psbt'])['hex'])
 
+        # feeRate of 0.1 BTC / KB produces a total fee slightly below -maxtxfee (~0.05280000):
+        res = self.nodes[1].walletcreatefundedpsbt([{"txid":txid,"vout":p2wpkh_pos},{"txid":txid,"vout":p2sh_p2wpkh_pos},{"txid":txid,"vout":p2pkh_pos}], {self.nodes[1].getnewaddress():29.99}, 0, {"feeRate": 0.1})
+        assert_greater_than(res["fee"], 0.05)
+        assert_greater_than(0.06, res["fee"])
+
+        # feeRate of 10 BTC / KB produces a total fee well above -maxtxfee
+        # previously this was silenty capped at -maxtxfee
+        assert_raises_rpc_error(-4, "Fee exceeds maximum configured by -maxtxfee", self.nodes[1].walletcreatefundedpsbt, [{"txid":txid,"vout":p2wpkh_pos},{"txid":txid,"vout":p2sh_p2wpkh_pos},{"txid":txid,"vout":p2pkh_pos}], {self.nodes[1].getnewaddress():29.99}, 0, {"feeRate": 10})
+
         # partially sign multisig things with node 1
         psbtx = self.nodes[1].walletcreatefundedpsbt([{"txid":txid,"vout":p2wsh_pos},{"txid":txid,"vout":p2sh_pos},{"txid":txid,"vout":p2sh_p2wsh_pos}], {self.nodes[1].getnewaddress():29.99})['psbt']
         walletprocesspsbt_out = self.nodes[1].walletprocesspsbt(psbtx)