Randomize extra_nonce

To guarantee that hashing blobs will be different between different p2pool nodes, even if they mine to the same wallet address and don't have transactions to shuffle within the block template.

src/miner.cpp

@@ -25,6 +25,7 @@
 #include "params.h"
 #include "p2pool_api.h"
 #include "side_chain.h"
+#include "p2p_server.h"
 #include <thread>
 
 static constexpr char log_category_prefix[] = "Miner ";
@@ -40,7 +41,7 @@ Miner::Miner(p2pool* pool, uint32_t threads)
 	, m_startTimestamp(high_resolution_clock::now())
 	, m_nonce(0)
 	, m_nonceTimestamp(m_startTimestamp)
-	, m_extraNonce(0xF19E3779U)
+	, m_extraNonce(static_cast<uint32_t>(pool->p2p_server()->get_random64()))
 	, m_totalHashes(0)
 	, m_sharesFound(0)
 	, m_job{}

src/stratum_server.cpp

@@ -45,7 +45,6 @@ StratumServer::StratumServer(p2pool* pool)
 	: TCPServer(StratumClient::allocate)
 	, m_pool(pool)
 	, m_autoDiff(pool->params().m_autoDiff)
-	, m_extraNonce(0)
 	, m_rng(RandomDeviceSeed::instance)
 	, m_cumulativeHashes(0)
 	, m_cumulativeHashesAtLastShare(0)
@@ -60,6 +59,8 @@ StratumServer::StratumServer(p2pool* pool)
 	// Diffuse the initial state in case it has low quality
 	m_rng.discard(10000);
 
+	m_extraNonce = static_cast<uint32_t>(m_rng());
+
 	m_hashrateData[0] = { seconds_since_epoch(), 0 };
 
 	uv_mutex_init_checked(&m_blobsQueueLock);
@@ -104,9 +105,12 @@ void StratumServer::on_block(const BlockTemplate& block)
 		LOGINFO(4, "no clients connected");
 		return;
 	}
-	m_extraNonce.exchange(num_connections);
+
+	const uint32_t extra_nonce_start = static_cast<uint32_t>(get_random64());
+	m_extraNonce.exchange(extra_nonce_start + num_connections);
 
 	BlobsData* blobs_data = new BlobsData{};
+	blobs_data->m_extraNonceStart = extra_nonce_start;
 
 	difficulty_type difficulty;
 	difficulty_type sidechain_difficulty;
@@ -116,7 +120,7 @@ void StratumServer::on_block(const BlockTemplate& block)
 	// Even if they do, they'll be added to the beginning of the list and will get their block template in on_login()
 	// We'll iterate through the list backwards so when we get to the beginning and run out of extra_nonce values, it'll be only new clients left
 	blobs_data->m_numClientsExpected = num_connections;
-	blobs_data->m_blobSize = block.get_hashing_blobs(0, num_connections, blobs_data->m_blobs, blobs_data->m_height, difficulty, sidechain_difficulty, blobs_data->m_seedHash, nonce_offset, blobs_data->m_templateId);
+	blobs_data->m_blobSize = block.get_hashing_blobs(extra_nonce_start, num_connections, blobs_data->m_blobs, blobs_data->m_height, difficulty, sidechain_difficulty, blobs_data->m_seedHash, nonce_offset, blobs_data->m_templateId);
 
 	// Integrity checks
 	if (blobs_data->m_blobSize < 76) {
@@ -662,9 +666,10 @@ void StratumServer::on_blobs_ready()
 
 	// Only send the latest blob
 	BlobsData* data = blobs_queue.back();
+	const uint32_t extra_nonce_start = data->m_extraNonceStart;
 
 	size_t numClientsProcessed = 0;
-	uint32_t extra_nonce = 0;
+	uint32_t num_sent = 0;
 
 	const uint64_t cur_time = seconds_since_epoch();
 	{
@@ -683,12 +688,12 @@ void StratumServer::on_blobs_ready()
 				continue;
 			}
 
-			if (extra_nonce >= data->m_numClientsExpected) {
+			if (num_sent >= data->m_numClientsExpected) {
 				// We don't have any more extra_nonce values available
 				continue;
 			}
 
-			uint8_t* hashing_blob = data->m_blobs.data() + extra_nonce * data->m_blobSize;
+			uint8_t* hashing_blob = data->m_blobs.data() + num_sent * data->m_blobSize;
 
 			uint64_t target = data->m_target;
 			if (client->m_customDiff.lo) {
@@ -724,7 +729,7 @@ void StratumServer::on_blobs_ready()
 
 				StratumClient::SavedJob& saved_job = client->m_jobs[job_id % StratumClient::JOBS_SIZE];
 				saved_job.job_id = job_id;
-				saved_job.extra_nonce = extra_nonce;
+				saved_job.extra_nonce = extra_nonce_start + num_sent;
 				saved_job.template_id = data->m_templateId;
 				saved_job.target = target;
 			}
@@ -750,7 +755,7 @@ void StratumServer::on_blobs_ready()
 				});
 
 			if (result) {
-				++extra_nonce;
+				++num_sent;
 			}
 			else {
 				client->close();
@@ -763,7 +768,7 @@ void StratumServer::on_blobs_ready()
 		}
 	}
 
-	LOGINFO(3, "sent new job to " << extra_nonce << '/' << numClientsProcessed << " clients");
+	LOGINFO(3, "sent new job to " << num_sent << '/' << numClientsProcessed << " clients");
 }
 
 void StratumServer::update_hashrate_data(uint64_t hashes, uint64_t timestamp)

src/stratum_server.h

@@ -103,6 +103,7 @@ private:
 
 	struct BlobsData
 	{
+		uint32_t m_extraNonceStart;
 		std::vector<uint8_t> m_blobs;
 		size_t m_blobSize;
 		uint64_t m_target;