From e9c14ef3d018364e0f441a7aa404a40f9068e59f Mon Sep 17 00:00:00 2001
From: SChernykh <15806605+SChernykh@users.noreply.github.com>
Date: Sun, 28 Sep 2025 15:33:58 +0200
Subject: [PATCH] Don't send the same Monero block broadcast to peers who sent
 it already

---
 src/p2p_server.cpp | 19 ++++++++++++-------
 src/p2p_server.h   |  4 +++-
 src/p2pool.cpp     |  6 +++++-
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/src/p2p_server.cpp b/src/p2p_server.cpp
index b62489a..53dd20b 100644
--- a/src/p2p_server.cpp
+++ b/src/p2p_server.cpp
@@ -1712,13 +1712,19 @@ void P2PServer::broadcast_monero_block(const uint8_t* data, uint32_t data_size,
 		return;
 	}
 
-	if (!duplicate_check_done && !store_monero_block_broadcast(data + sizeof(MoneroBlockBroadcastHeader), data_size - sizeof(MoneroBlockBroadcastHeader))) {
+	hash digest;
+	sha256(data + sizeof(MoneroBlockBroadcastHeader), data_size - sizeof(MoneroBlockBroadcastHeader), digest.h);
+
+	if (!duplicate_check_done && !store_monero_block_broadcast(digest)) {
 		LOGINFO(6, "broadcast_monero_block: skipping duplicate broadcast");
 		return;
 	}
 
 	for (P2PClient* client = static_cast<P2PClient*>(m_connectedClientsList->m_next); client != m_connectedClientsList; client = static_cast<P2PClient*>(client->m_next)) {
-		if ((source && (client == source)) || !client->is_good() || (client->m_protocolVersion < PROTOCOL_VERSION_1_4)) {
+		if ((source && (client == source)) ||
+			!client->is_good() ||
+			(client->m_protocolVersion < PROTOCOL_VERSION_1_4) ||
+			(client->m_lastMoneroBlockBroadcastDigest == digest)) {
 			continue;
 		}
 
@@ -1749,11 +1755,8 @@ void P2PServer::broadcast_monero_block(const uint8_t* data, uint32_t data_size,
 	}
 }
 
-bool P2PServer::store_monero_block_broadcast(const uint8_t* data, uint32_t data_size)
+bool P2PServer::store_monero_block_broadcast(const hash& digest)
 {
-	hash digest;
-	sha256(data, data_size, digest.h);
-
 	// Every message can be received from multiple peers, so broadcast it only once
 	MutexLock lock(m_MoneroBlockBroadcastsLock);
 	return m_MoneroBlockBroadcasts.emplace(*digest.u64(), seconds_since_epoch()).second;
@@ -3069,8 +3072,10 @@ bool P2PServer::P2PClient::on_monero_block_broadcast(const uint8_t* buf, uint32_
 		return true;
 	}
 
+	sha256(buf, size, m_lastMoneroBlockBroadcastDigest.h);
+
 	// Ignore repeated old messages
-	if (!server->store_monero_block_broadcast(buf, size)) {
+	if (!server->store_monero_block_broadcast(m_lastMoneroBlockBroadcastDigest)) {
 		LOGINFO(6, "Repeated MONERO_BLOCK_BROADCAST - ignored");
 		return true;
 	}
diff --git a/src/p2p_server.h b/src/p2p_server.h
index 0ed3b4d..9b5b7a4 100644
--- a/src/p2p_server.h
+++ b/src/p2p_server.h
@@ -162,6 +162,8 @@ public:
 		hash m_broadcastedHashes[8];
 		uint32_t m_broadcastedHashesIndex;
 
+		hash m_lastMoneroBlockBroadcastDigest;
+
 		// log::Stream wrapper
 		struct SoftwareDisplayName
 		{
@@ -220,7 +222,7 @@ public:
 	void broadcast_monero_block_handler();
 	void broadcast_monero_block(const uint8_t* data, uint32_t data_size, const P2PClient* source, bool duplicate_check_done);
 
-	bool store_monero_block_broadcast(const uint8_t* data, uint32_t data_size);
+	bool store_monero_block_broadcast(const hash& digest);
 
 private:
 	[[nodiscard]] const char* get_log_category() const override;
diff --git a/src/p2pool.cpp b/src/p2pool.cpp
index 2f87d88..0167e54 100644
--- a/src/p2pool.cpp
+++ b/src/p2pool.cpp
@@ -42,6 +42,7 @@
 #include "keccak.h"
 #include "merkle.h"
 #include "merge_mining_client.h"
+#include "sha256.h"
 
 #ifdef WITH_TLS
 #include <openssl/curve25519.h>
@@ -1146,7 +1147,10 @@ void p2pool::submit_block() const
 	}
 	request.append("\"]}");
 
-	m_p2pServer->store_monero_block_broadcast(blob.data(), static_cast<uint32_t>(blob.size()));
+	hash digest;
+	sha256(blob.data(), static_cast<uint32_t>(blob.size()), digest.h);
+
+	m_p2pServer->store_monero_block_broadcast(digest);
 
 	const Params::Host& host = current_host();