From 48618daf262b84c2e2f7322b5ca14375d7d68b64 Mon Sep 17 00:00:00 2001
From: Anthony Towns <aj@erisian.com.au>
Date: Thu, 9 Aug 2018 01:52:42 +1000
Subject: [PATCH] Add checks for settxfee reasonableness

---
 src/wallet/rpcwallet.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 281fd4614..46162556e 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -2982,8 +2982,16 @@ static UniValue settxfee(const JSONRPCRequest& request)
     LOCK2(cs_main, pwallet->cs_wallet);
 
     CAmount nAmount = AmountFromValue(request.params[0]);
+    CFeeRate tx_fee_rate(nAmount, 1000);
+    if (tx_fee_rate == 0) {
+        // automatic selection
+    } else if (tx_fee_rate < ::minRelayTxFee) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("txfee cannot be less than min relay tx fee (%s)", ::minRelayTxFee.ToString()));
+    } else if (tx_fee_rate < pwallet->m_min_fee) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("txfee cannot be less than wallet min fee (%s)", pwallet->m_min_fee.ToString()));
+    }
 
-    pwallet->m_pay_tx_fee = CFeeRate(nAmount, 1000);
+    pwallet->m_pay_tx_fee = tx_fee_rate;
     return true;
 }