avoid stack overflow and div by zero

eth/main.cpp

@@ -1115,13 +1115,33 @@ int main(int argc, char** argv)
 			else if (c && cmd == "setblockfees")
 			{
 				iss >> blockFees;
-				gasPricer->setRefBlockFees(u256(blockFees * 1000));
+				try
+				{
+					gasPricer->setRefBlockFees(u256(blockFees * 1000));
+				}
+				catch(Overflow const& _e)
+				{
+					cout << boost::diagnostic_information(_e);
+				}
+
 				cout << "Block fees: " << blockFees << endl;
 			}
 			else if (c && cmd == "setetherprice")
 			{
 				iss >> etherPrice;
-				gasPricer->setRefPrice(u256(double(ether / 1000) / etherPrice));
+				if (etherPrice == 0)
+					cout << "ether price can not be set to zero" << endl;
+				else
+				{
+					try
+					{
+						gasPricer->setRefPrice(u256(double(ether / 1000) / etherPrice));
+					}
+					catch(Overflow const& _e)
+					{
+						cout << boost::diagnostic_information(_e);
+					}
+				}
 				cout << "ether Price: " << etherPrice << endl;
 			}
 			else if (c && cmd == "setpriority")

libdevcore/Exceptions.h

@@ -51,6 +51,7 @@ struct NoUPnPDevice: virtual Exception {};
 struct RootNotFound: virtual Exception {};
 struct BadRoot: virtual Exception {};
 struct FileError: virtual Exception {};
+struct Overflow: virtual Exception {};
 struct InterfaceNotSupported: virtual Exception { public: InterfaceNotSupported(std::string _f): Exception("Interface " + _f + " not supported.") {} };
 
 // error information to be added to exceptions

libethereum/Client.h

@@ -77,8 +77,8 @@ class BasicGasPricer: public GasPricer
 public:
 	explicit BasicGasPricer(u256 _weiPerRef, u256 _refsPerBlock): m_weiPerRef(_weiPerRef), m_refsPerBlock(_refsPerBlock) {}
 
-	void setRefPrice(u256 _weiPerRef) { m_weiPerRef = _weiPerRef; }
-	void setRefBlockFees(u256 _refsPerBlock) { m_refsPerBlock = _refsPerBlock; }
+	void setRefPrice(u256 _weiPerRef) { if ((bigint)m_refsPerBlock * _weiPerRef > std::numeric_limits<u256>::max() ) BOOST_THROW_EXCEPTION(Overflow() << errinfo_comment("ether price * block fees is larger than 2**256-1, choose a smaller number.") ); else m_weiPerRef = _weiPerRef; }
+	void setRefBlockFees(u256 _refsPerBlock) { if ((bigint)m_weiPerRef * _refsPerBlock > std::numeric_limits<u256>::max() ) BOOST_THROW_EXCEPTION(Overflow() << errinfo_comment("ether price * block fees is larger than 2**256-1, choose a smaller number.") ); else m_refsPerBlock = _refsPerBlock; }
 
 	u256 ask(State const&) const override { return m_weiPerRef * m_refsPerBlock / m_gasPerBlock; }
 	u256 bid(TransactionPriority _p = TransactionPriority::Medium) const override { return m_octiles[(int)_p] > 0 ? m_octiles[(int)_p] : (m_weiPerRef * m_refsPerBlock / m_gasPerBlock); }

neth/main.cpp

@@ -718,13 +718,33 @@ int main(int argc, char** argv)
 		else if (c && cmd == "setblockfees")
 		{
 			iss >> blockFees;
-			gasPricer->setRefBlockFees(u256(blockFees * 1000));
+			try
+			{
+				gasPricer->setRefBlockFees(u256(blockFees * 1000));
+			}
+			catch(Overflow const& _e)
+			{
+				cout << boost::diagnostic_information(_e);
+			}
+
 			cout << "Block fees: " << blockFees << endl;
 		}
 		else if (c && cmd == "setetherprice")
 		{
 			iss >> etherPrice;
-			gasPricer->setRefPrice(u256(double(ether / 1000) / etherPrice));
+			if (etherPrice == 0)
+				cout << "ether price can not be set to zero" << endl;
+			else
+			{
+				try
+				{
+					gasPricer->setRefPrice(u256(double(ether / 1000) / etherPrice));
+				}
+				catch(Overflow const& _e)
+				{
+					cout << boost::diagnostic_information(_e);
+				}
+			}
 			cout << "ether Price: " << etherPrice << endl;
 		}
 		else if (c && cmd == "setpriority")

test/libethereum/gaspricer.cpp

@@ -0,0 +1 @@
+