From 0c85dc30e6b628f7538a67776c7eefcb84ef4f82 Mon Sep 17 00:00:00 2001
From: Martin Zumsande <mzumsande@gmail.com>
Date: Mon, 29 Nov 2021 16:33:00 +0100
Subject: [PATCH] p2p: Don't use timestamps from inbound peers

This makes it harder for others to tamper with
our adjusted time.
---
 src/net_processing.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index a896bb76aee..ebabba5c784 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -2683,7 +2683,11 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
 
         int64_t nTimeOffset = nTime - GetTime();
         pfrom.nTimeOffset = nTimeOffset;
-        AddTimeData(pfrom.addr, nTimeOffset);
+        if (!pfrom.IsInboundConn()) {
+            // Don't use timedata samples from inbound peers to make it
+            // harder for others to tamper with our adjusted time.
+            AddTimeData(pfrom.addr, nTimeOffset);
+        }
 
         // If the peer is old enough to have the old alert system, send it the final alert.
         if (greatest_common_version <= 70012) {