Refactored RNG usage across the code

src/common.h

@@ -54,6 +54,7 @@
 #include <atomic>
 #include <chrono>
 #include <iostream>
+#include <random>
 
 #include <signal.h>
 

src/crypto.cpp

@@ -19,7 +19,6 @@
 #include "crypto.h"
 #include "keccak.h"
 #include "uv_util.h"
-#include <random>
 
 extern "C" {
 #include "crypto-ops.h"
@@ -32,7 +31,7 @@ namespace {
 class RandomBytes
 {
 public:
-	RandomBytes() : rng(s), dist(0, 255)
+	RandomBytes() : rng(RandomDeviceSeed::instance), dist(0, 255)
 	{
 		uv_mutex_init_checked(&m);
 
@@ -57,22 +56,6 @@ public:
 private:
 	uv_mutex_t m;
 
-	// Fills the whole initial MT19937-64 state with non-deterministic random numbers
-	struct SeedSequence
-	{
-		using result_type = std::random_device::result_type;
-
-		template<typename T>
-		static void generate(T begin, T end)
-		{
-			std::random_device rd;
-			for (T i = begin; i != end; ++i) {
-				*i = rd();
-			}
-		}
-	};
-
-	SeedSequence s;
 	std::mt19937_64 rng;
 	std::uniform_int_distribution<> dist;
 };

src/p2p_server.cpp

@@ -47,15 +47,18 @@ P2PServer::P2PServer(p2pool* pool)
 	, m_cache(pool->params().m_blockCache ? new BlockCache() : nullptr)
 	, m_cacheLoaded(false)
 	, m_initialPeerList(pool->params().m_p2pPeerList)
-	, m_rd{}
-	, m_rng(m_rd())
+	, m_rng(RandomDeviceSeed::instance)
 	, m_block(new PoolBlock())
 	, m_timer{}
 	, m_timerCounter(0)
 	, m_timerInterval(2)
-	, m_peerId(m_rng())
 	, m_peerListLastSaved(0)
 {
+	// Diffuse the initial state in case it has low quality
+	m_rng.discard(10000);
+
+	m_peerId = m_rng();
+
 	set_max_outgoing_peers(pool->params().m_maxOutgoingPeers);
 	set_max_incoming_peers(pool->params().m_maxIncomingPeers);
 

src/p2p_server.h

@@ -18,7 +18,6 @@
 #pragma once
 
 #include "tcp_server.h"
-#include <random>
 
 namespace p2pool {
 
@@ -170,7 +169,6 @@ private:
 	void remove_peer_from_list(const raw_ip& ip);
 
 	uv_mutex_t m_rngLock;
-	std::random_device m_rd;
 	std::mt19937_64 m_rng;
 
 	uv_mutex_t m_blockLock;

src/stratum_server.cpp

@@ -39,8 +39,7 @@ StratumServer::StratumServer(p2pool* pool)
 	: TCPServer(StratumClient::allocate)
 	, m_pool(pool)
 	, m_extraNonce(0)
-	, m_rd{}
-	, m_rng(m_rd())
+	, m_rng(RandomDeviceSeed::instance)
 	, m_cumulativeHashes(0)
 	, m_cumulativeHashesAtLastShare(0)
 	, m_hashrateDataHead(0)
@@ -51,6 +50,9 @@ StratumServer::StratumServer(p2pool* pool)
 	, m_totalFoundShares(0)
 	, m_apiLastUpdateTime(0)
 {
+	// Diffuse the initial state in case it has low quality
+	m_rng.discard(10000);
+
 	m_hashrateData[0] = { time(nullptr), 0 };
 
 	uv_mutex_init_checked(&m_blobsQueueLock);

src/stratum_server.h

@@ -19,7 +19,6 @@
 
 #include "tcp_server.h"
 #include <rapidjson/document.h>
-#include <random>
 
 namespace p2pool {
 
@@ -109,7 +108,6 @@ private:
 	std::atomic<uint32_t> m_extraNonce;
 
 	uv_mutex_t m_rngLock;
-	std::random_device m_rd;
 	std::mt19937_64 m_rng;
 
 	struct SubmittedShare

src/util.cpp

@@ -382,4 +382,6 @@ bool resolve_host(std::string& host, bool& is_v6)
 	return true;
 }
 
+RandomDeviceSeed RandomDeviceSeed::instance;
+
 } // namespace p2pool

src/util.h

@@ -145,6 +145,24 @@ using unordered_map = robin_hood::detail::Table<false, 80, Key, T, robin_hood::h
 template <typename Key>
 using unordered_set = robin_hood::detail::Table<false, 80, Key, void, robin_hood::hash<Key>, std::equal_to<Key>>;
 
+// Fills the whole initial MT19937-64 state with non-deterministic random numbers
+struct RandomDeviceSeed
+{
+	using result_type = std::random_device::result_type;
+	static_assert(sizeof(result_type) >= 4, "result_type must have at least 32 bits");
+
+	template<typename T>
+	static void generate(T begin, T end)
+	{
+		std::random_device rd;
+		for (T i = begin; i != end; ++i) {
+			*i = rd();
+		}
+	}
+
+	static RandomDeviceSeed instance;
+};
+
 } // namespace p2pool
 
 namespace robin_hood {

src/zmq_reader.cpp

@@ -19,7 +19,6 @@
 #include "zmq_reader.h"
 #include "json_parsers.h"
 #include <rapidjson/document.h>
-#include <random>
 
 static constexpr char log_category_prefix[] = "ZMQReader ";