From 541cef55b84e5fa09cd7e6af2ec4b6cc80cc0854 Mon Sep 17 00:00:00 2001
From: Andrew Camilleri <evilkukka@gmail.com>
Date: Thu, 14 Dec 2023 13:20:45 +0100
Subject: [PATCH] Random feerate and ensure sanity (#5556)

Suggested at https://github.com/btcpayserver/btcpayserver/pull/5490#issuecomment-1851066223
We can also configure this httpclient to use tor
---
 .../Services/Fees/MempoolSpaceFeeProvider.cs      | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/BTCPayServer/Services/Fees/MempoolSpaceFeeProvider.cs b/BTCPayServer/Services/Fees/MempoolSpaceFeeProvider.cs
index 703978b7b..fb0f64da1 100644
--- a/BTCPayServer/Services/Fees/MempoolSpaceFeeProvider.cs
+++ b/BTCPayServer/Services/Fees/MempoolSpaceFeeProvider.cs
@@ -56,9 +56,22 @@ public class MempoolSpaceFeeProvider(
                     "minimumFee" => 144,
                     _ => -1
                 };
-                feesByBlockTarget.TryAdd(target, new FeeRate(value));
+                feesByBlockTarget.TryAdd(target, new FeeRate(RandomizeByPercentage(value, 10)));
             }
             return feesByBlockTarget;
         })!;
     }
+    
+    static decimal RandomizeByPercentage(decimal value, int percentage)
+    {
+        decimal range = value * percentage / 100m;
+        var res = value + range * (Random.Shared.NextDouble() < 0.5 ? -1 : 1);
+
+        return res switch
+        {
+            < 1m => 1m,
+            > 850 => 850,
+            _ => res
+        };
+    }
 }