thread safe rand (#1157)

* thread safe InsecureRand class

* remove GetInsecureRand, use GetRandInt for performance non-critical parts

src/darksend.cpp

@@ -664,7 +664,7 @@ void CDarksendPool::ChargeFees()
     if(!fMasterNode) return;
 
     //we don't need to charge collateral for every offence.
-    if(GetInsecureRand(100) > 33) return;
+    if(GetRandInt(100) > 33) return;
 
     std::vector<CTransaction> vecOffendersCollaterals;
 
@@ -699,7 +699,7 @@ void CDarksendPool::ChargeFees()
     if(vecOffendersCollaterals.empty()) return;
 
     //mostly offending? Charge sometimes
-    if((int)vecOffendersCollaterals.size() >= Params().PoolMaxTransactions() - 1 && GetInsecureRand(100) > 33) return;
+    if((int)vecOffendersCollaterals.size() >= Params().PoolMaxTransactions() - 1 && GetRandInt(100) > 33) return;
 
     //everyone is an offender? That's not right
     if((int)vecOffendersCollaterals.size() >= Params().PoolMaxTransactions()) return;
@@ -740,7 +740,7 @@ void CDarksendPool::ChargeRandomFees()
 
     BOOST_FOREACH(const CTransaction& txCollateral, vecSessionCollaterals) {
 
-        if(GetInsecureRand(100) > 10) return;
+        if(GetRandInt(100) > 10) return;
 
         LogPrintf("CDarksendPool::ChargeRandomFees -- charging random fees, txCollateral=%s", txCollateral.ToString());
 
@@ -1480,7 +1480,7 @@ bool CDarksendPool::DoAutomaticDenominating(bool fDryRun)
         LogPrint("privatesend", "  vecMasternodesUsed: new size: %d, threshold: %d\n", (int)vecMasternodesUsed.size(), nThreshold_high);
     }
 
-    bool fUseQueue = insecure_rand()%100 > 33;
+    bool fUseQueue = GetRandInt(100) > 33;
     // don't use the queues all of the time for mixing unless we are a liquidity provider
     if(nLiquidityProvider || fUseQueue) {
 
@@ -2014,7 +2014,7 @@ bool CDarksendPool::CreateNewSession(int nDenom, CTransaction txCollateral, Pool
 
     // start new session
     nMessageIDRet = MSG_NOERR;
-    nSessionID = GetInsecureRand(999999)+1;
+    nSessionID = GetRandInt(999999)+1;
     nSessionDenom = nDenom;
 
     SetState(POOL_STATE_QUEUE);
@@ -2145,7 +2145,7 @@ int CDarksendPool::GetDenominations(const std::vector<CTxOut>& vecTxOut, bool fS
     int c = 0;
     // if the denomination is used, shift the bit on
     BOOST_FOREACH (PAIRTYPE(CAmount, int)& s, vecDenomUsed) {
-        int bit = (fSingleRandomDenom ? insecure_rand()%2 : 1) & s.second;
+        int bit = (fSingleRandomDenom ? GetRandInt(2) : 1) & s.second;
         nDenom |= bit << c++;
         if(fSingleRandomDenom && bit) break; // use just one random denomination
     }
@@ -2462,7 +2462,7 @@ void ThreadCheckDarkSendPool()
 
             if(nDoAutoNextRun == nTick) {
                 darkSendPool.DoAutomaticDenominating();
-                nDoAutoNextRun = nTick + PRIVATESEND_AUTO_TIMEOUT_MIN + GetInsecureRand(PRIVATESEND_AUTO_TIMEOUT_MAX - PRIVATESEND_AUTO_TIMEOUT_MIN);
+                nDoAutoNextRun = nTick + PRIVATESEND_AUTO_TIMEOUT_MIN + GetRandInt(PRIVATESEND_AUTO_TIMEOUT_MAX - PRIVATESEND_AUTO_TIMEOUT_MIN);
             }
         }
     }

src/masternodeman.cpp

@@ -543,8 +543,9 @@ CMasternode* CMasternodeMan::FindRandomNotInVec(const std::vector<CTxIn> &vecToE
         vpMasternodesShuffled.push_back(&mn);
     }
 
+    InsecureRand insecureRand;
     // shuffle pointers
-    std::random_shuffle(vpMasternodesShuffled.begin(), vpMasternodesShuffled.end(), GetInsecureRand);
+    std::random_shuffle(vpMasternodesShuffled.begin(), vpMasternodesShuffled.end(), insecureRand);
     bool fExclude;
 
     // loop through
@@ -969,7 +970,7 @@ bool CMasternodeMan::SendVerifyRequest(const CAddress& addr, const std::vector<C
     if(pnode != NULL) {
         netfulfilledman.AddFulfilledRequest(addr, strprintf("%s", NetMsgType::MNVERIFY)+"-request");
         // use random nonce, store it and require node to reply with correct one later
-        CMasternodeVerification mnv(addr, GetInsecureRand(999999), pCurrentBlockIndex->nHeight - 1);
+        CMasternodeVerification mnv(addr, GetRandInt(999999), pCurrentBlockIndex->nHeight - 1);
         mWeAskedForVerification[addr] = mnv;
         LogPrintf("CMasternodeMan::SendVerifyRequest -- verifying using nonce %d addr=%s\n", mnv.nonce, addr.ToString());
         pnode->PushMessage(NetMsgType::MNVERIFY, mnv);

src/random.cpp

@@ -137,3 +137,21 @@ void seed_insecure_rand(bool fDeterministic)
         insecure_rand_Rw = tmp;
     }
 }
+
+InsecureRand::InsecureRand(bool _fDeterministic)
+    : nRz(11),
+      nRw(11),
+      fDeterministic(_fDeterministic)
+{
+    // The seed values have some unlikely fixed points which we avoid.
+    if(fDeterministic) return;
+    uint32_t nTmp;
+    do {
+        GetRandBytes((unsigned char*)&nTmp, 4);
+    } while (nTmp == 0 || nTmp == 0x9068ffffU);
+    nRz = nTmp;
+    do {
+        GetRandBytes((unsigned char*)&nTmp, 4);
+    } while (nTmp == 0 || nTmp == 0x464fffffU);
+    nRw = nTmp;
+}

src/random.h

@@ -47,10 +47,31 @@ static inline uint32_t insecure_rand(void)
 }
 
 /**
- * Function for std::random_shuffle
+ * PRNG initialized from secure entropy based RNG
  */
-static inline uint32_t GetInsecureRand(uint32_t i){
-    return insecure_rand() % i;
-}
+class InsecureRand
+{
+private:
+    uint32_t nRz;
+    uint32_t nRw;
+    bool fDeterministic;
+
+public:
+    InsecureRand(bool _fDeterministic = false);
+
+   /**
+    * MWC RNG of George Marsaglia
+    * This is intended to be fast. It has a period of 2^59.3, though the
+    * least significant 16 bits only have a period of about 2^30.1.
+    *
+    * @return random value < nMax
+    */
+    int64_t operator()(int64_t nMax)
+    {
+        nRz = 36969 * (nRz & 65535) + (nRz >> 16);
+        nRw = 18000 * (nRw & 65535) + (nRw >> 16);
+        return ((nRw << 16) + nRz) % nMax;
+    }
+};
 
 #endif // BITCOIN_RANDOM_H

src/wallet/wallet.cpp

@@ -2501,6 +2501,7 @@ bool CWallet::SelectCoinsByDenominations(int nDenom, CAmount nValueMin, CAmount
 
     int nDenomResult = 0;
 
+    InsecureRand insecureRand;
     BOOST_FOREACH(const COutput& out, vCoins)
     {
         // masternode-like input should not be selected by AvailableCoins now anyway
@@ -2517,9 +2518,9 @@ bool CWallet::SelectCoinsByDenominations(int nDenom, CAmount nValueMin, CAmount
                 if(out.tx->vout[out.i].nValue == vecPrivateSendDenominations[nBit]) {
                     if(nValueRet >= nValueMin) {
                         //randomly reduce the max amount we'll submit (for anonymity)
-                        nValueMax -= (GetInsecureRand(nValueMax/5));
+                        nValueMax -= insecureRand(nValueMax/5);
                         //on average use 50% of the inputs or less
-                        int r = GetInsecureRand((int)vCoins.size());
+                        int r = insecureRand(vCoins.size());
                         if((int)vecTxInRet.size() > r) return true;
                     }
                     txin.prevPubKey = out.tx->vout[out.i].scriptPubKey; // the inputs PubKey