common rng for random shuffle

libi2pd/TunnelPool.h

@@ -15,6 +15,7 @@
 #include <utility>
 #include <mutex>
 #include <memory>
+#include <random>
 #include "Identity.h"
 #include "LeaseSet.h"
 #include "RouterInfo.h"
@@ -115,6 +116,8 @@ namespace tunnel
 			std::shared_ptr<const i2p::data::RouterInfo> SelectNextHop (std::shared_ptr<const i2p::data::RouterInfo> prevHop, bool reverse, bool endpoint) const;
 			bool StandardSelectPeers(Path & path, int numHops, bool inbound, SelectHopFunc nextHop);
 
+			std::mt19937& GetRng () { return m_Rng; }
+			
 		private:
 
 			void TestTunnels ();
@@ -148,6 +151,9 @@ namespace tunnel
 			uint64_t m_MinLatency = 0; // if > 0 this tunnel pool will try building tunnels with minimum latency by ms
 			uint64_t m_MaxLatency = 0; // if > 0 this tunnel pool will try building tunnels with maximum latency by ms
 
+			std::random_device m_Rd;
+			std::mt19937 m_Rng;
+			
 		public:
 
 			// for HTTP only