From b2f86a5f6bc2498b05830381c4867b4fac7e2a03 Mon Sep 17 00:00:00 2001
From: SChernykh <sergey.v.chernykh@gmail.com>
Date: Sat, 23 Apr 2022 11:29:17 +0200
Subject: [PATCH] Ban peers with stuck or lagging monerod

---
 src/p2p_server.cpp | 17 ++++++++++++++++-
 src/p2p_server.h   |  1 +
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/p2p_server.cpp b/src/p2p_server.cpp
index 4aa49bb..51055a2 100644
--- a/src/p2p_server.cpp
+++ b/src/p2p_server.cpp
@@ -1030,6 +1030,7 @@ P2PServer::P2PClient::P2PClient()
 	, m_peerListPendingRequests(0)
 	, m_pingTime(0)
 	, m_blockPendingRequests(0)
+	, m_chainTipBlockRequest(false)
 	, m_lastAlive(0)
 	, m_lastBroadcastTimestamp(0)
 	, m_lastBlockrequestTimestamp(0)
@@ -1059,6 +1060,7 @@ void P2PServer::P2PClient::reset()
 	m_peerListPendingRequests = 0;
 	m_pingTime = 0;
 	m_blockPendingRequests = 0;
+	m_chainTipBlockRequest = false;
 	m_lastAlive = 0;
 	m_lastBroadcastTimestamp = 0;
 	m_lastBlockrequestTimestamp = 0;
@@ -1642,6 +1644,7 @@ void P2PServer::P2PClient::on_after_handshake(uint8_t* &p)
 	p += HASH_SIZE;
 
 	++m_blockPendingRequests;
+	m_chainTipBlockRequest = true;
 	m_lastBroadcastTimestamp = seconds_since_epoch();
 }
 
@@ -1714,6 +1717,18 @@ bool P2PServer::P2PClient::on_block_response(const uint8_t* buf, uint32_t size)
 		return false;
 	}
 
+	if (m_chainTipBlockRequest) {
+		m_chainTipBlockRequest = false;
+
+		const uint64_t peer_height = server->m_block->m_txinGenHeight;
+		const uint64_t our_height = server->m_pool->miner_data().height;
+
+		if (peer_height + 2 < our_height) {
+			LOGWARN(4, "peer " << static_cast<char*>(m_addrString) << " is mining on top of a stale block (mainchain height " << peer_height << ", expected >= " << our_height << ')');
+			return false;
+		}
+	}
+
 	return handle_incoming_block_async(server->m_block);
 }
 
@@ -1756,7 +1771,7 @@ bool P2PServer::P2PClient::on_block_broadcast(const uint8_t* buf, uint32_t size)
 				}
 			}
 			else {
-				LOGWARN(5, "peer " << static_cast<char*>(m_addrString) << " broadcasted an unreasonably stale block (mainchain height " << peer_height << ", expected >= " << our_height << ')');
+				LOGWARN(4, "peer " << static_cast<char*>(m_addrString) << " broadcasted an unreasonably stale block (mainchain height " << peer_height << ", expected >= " << our_height << ')');
 				return false;
 			}
 		}
diff --git a/src/p2p_server.h b/src/p2p_server.h
index 0bdb8f1..35cc3e0 100644
--- a/src/p2p_server.h
+++ b/src/p2p_server.h
@@ -117,6 +117,7 @@ public:
 		int64_t m_pingTime;
 
 		int m_blockPendingRequests;
+		bool m_chainTipBlockRequest;
 
 		uint64_t m_lastAlive;
 		uint64_t m_lastBroadcastTimestamp;