rpc: configure gas cap (#457)

* rpc: configure gas cap

* c++

* rm old const

* docs

CHANGELOG.md

@@ -71,6 +71,7 @@ the Tracer type used to collect execution traces from the EVM transaction execut
 
 ### Improvements
 
+* (rpc) [tharsis#457](https://github.com/tharsis/ethermint/pull/457) Configure RPC gas cap through app config.
 * (evm) [tharsis#434](https://github.com/tharsis/ethermint/pull/434) Support different `Tracer` types for the EVM.
 * (deps) [tharsis#427](https://github.com/tharsis/ethermint/pull/427) Bump ibc-go to [`v1.0.0`](https://github.com/cosmos/ibc-go/releases/tag/v1.0.0)
 * (gRPC) [tharsis#239](https://github.com/tharsis/ethermint/pull/239) Query `ChainConfig` via gRPC.

docs/api/json-rpc/running_server.md

@@ -22,7 +22,19 @@ ethermintd start --json-rpc.enable
 ethermintd start --json-rpc.api eth,txpool,personal,net,debug,web3,miner
 ```
 
-### CORS
+## Set a Gas Cap
+
+`eth_call` and `eth_estimateGas` define a global gas cap over rpc for DoS protection. You can override the default gas cap value of 25,000,000 by passing a custom value when starting the node:
+
+```bash
+# set gas cap to 85M
+ethermintd start --json-rpc.gas-cap 85000000000
+
+# set gas cap to infinite (=0)
+ethermintd start --json-rpc.gas-cap 0
+```
+
+## CORS
 
 If accessing the RPC from a browser, CORS will need to be enabled with the appropriate domain set. Otherwise, JavaScript calls are limit by the same-origin policy and requests will fail:
 

ethereum/rpc/apis.go

@@ -36,7 +36,7 @@ const (
 // GetRPCAPIs returns the list of all APIs
 func GetRPCAPIs(ctx *server.Context, clientCtx client.Context, tmWSClient *rpcclient.WSClient, selectedAPIs []string) []rpc.API {
 	nonceLock := new(types.AddrLocker)
-	evmBackend := backend.NewEVMBackend(ctx.Logger, clientCtx)
+	evmBackend := backend.NewEVMBackend(ctx, ctx.Logger, clientCtx)
 
 	var apis []rpc.API
 	// remove duplicates

ethereum/rpc/backend/backend.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/client/flags"
 	codectypes "github.com/cosmos/cosmos-sdk/codec/types"
+	"github.com/cosmos/cosmos-sdk/server"
 	authtx "github.com/cosmos/cosmos-sdk/x/auth/tx"
 	"github.com/ethereum/go-ethereum/accounts/keystore"
 
@@ -28,6 +29,7 @@ import (
 	ethtypes "github.com/ethereum/go-ethereum/core/types"
 
 	"github.com/tharsis/ethermint/ethereum/rpc/types"
+	"github.com/tharsis/ethermint/server/config"
 	ethermint "github.com/tharsis/ethermint/types"
 	evmtypes "github.com/tharsis/ethermint/x/evm/types"
 )
@@ -48,6 +50,7 @@ type Backend interface {
 	BloomStatus() (uint64, uint64)
 	GetCoinbase() (sdk.AccAddress, error)
 	EstimateGas(args evmtypes.CallArgs, blockNrOptional *types.BlockNumber) (hexutil.Uint64, error)
+	RPCGasCap() uint64
 }
 
 var _ Backend = (*EVMBackend)(nil)
@@ -59,20 +62,28 @@ type EVMBackend struct {
 	queryClient *types.QueryClient // gRPC query client
 	logger      log.Logger
 	chainID     *big.Int
+	cfg         config.Config
 }
 
 // NewEVMBackend creates a new EVMBackend instance
-func NewEVMBackend(logger log.Logger, clientCtx client.Context) *EVMBackend {
+func NewEVMBackend(ctx *server.Context, logger log.Logger, clientCtx client.Context) *EVMBackend {
 	chainID, err := ethermint.ParseChainID(clientCtx.ChainID)
 	if err != nil {
 		panic(err)
 	}
+
+	appConf, err := config.ParseConfig(ctx.Viper)
+	if err != nil {
+		panic(err)
+	}
+
 	return &EVMBackend{
 		ctx:         context.Background(),
 		clientCtx:   clientCtx,
 		queryClient: types.NewQueryClient(clientCtx),
 		logger:      logger.With("module", "evm-backend"),
 		chainID:     chainID,
+		cfg:         *appConf,
 	}
 }
 
@@ -547,7 +558,8 @@ func (e *EVMBackend) EstimateGas(args evmtypes.CallArgs, blockNrOptional *types.
 	if err != nil {
 		return 0, err
 	}
-	req := evmtypes.EthCallRequest{Args: bz, GasCap: ethermint.DefaultRPCGasLimit}
+
+	req := evmtypes.EthCallRequest{Args: bz, GasCap: e.RPCGasCap()}
 
 	// From ContextWithHeight: if the provided height is 0,
 	// it will return an empty context and the gRPC query will use
@@ -581,3 +593,8 @@ func (e *EVMBackend) GetTransactionCount(address common.Address, blockNum types.
 	n := hexutil.Uint64(nonce)
 	return &n, nil
 }
+
+// RPCGasCap is the global gas cap for eth-call variants.
+func (e *EVMBackend) RPCGasCap() uint64 {
+	return e.cfg.JSONRPC.GasCap
+}

ethereum/rpc/backend/utils.go

@@ -12,7 +12,6 @@ import (
 
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/tharsis/ethermint/ethereum/rpc/types"
-	ethermint "github.com/tharsis/ethermint/types"
 	evmtypes "github.com/tharsis/ethermint/x/evm/types"
 )
 
@@ -21,10 +20,8 @@ import (
 func (e *EVMBackend) setTxDefaults(args types.SendTxArgs) (types.SendTxArgs, error) {
 
 	if args.GasPrice == nil {
-		// TODO: Change to either:
+		// TODO: Suggest a gas price based on the previous included txs
-		// - min gas price from context once available through server/daemon, or
+		args.GasPrice = (*hexutil.Big)(new(big.Int).SetUint64(e.RPCGasCap()))
-		// - suggest a gas price based on the previous included txs
-		args.GasPrice = (*hexutil.Big)(big.NewInt(ethermint.DefaultGasPrice))
 	}
 
 	if args.Nonce == nil {

ethereum/rpc/namespaces/eth/api.go

@@ -167,8 +167,7 @@ func (e *PublicAPI) Hashrate() hexutil.Uint64 {
 // GasPrice returns the current gas price based on Ethermint's gas price oracle.
 func (e *PublicAPI) GasPrice() *hexutil.Big {
 	e.logger.Debug("eth_gasPrice")
-	// TODO: use minimum value defined in config instead of default or implement oracle
+	out := new(big.Int).SetUint64(e.backend.RPCGasCap())
-	out := big.NewInt(ethermint.DefaultGasPrice)
 	return (*hexutil.Big)(out)
 }
 
@@ -438,7 +437,7 @@ func (e *PublicAPI) doCall(
 	if err != nil {
 		return nil, err
 	}
-	req := evmtypes.EthCallRequest{Args: bz, GasCap: ethermint.DefaultRPCGasLimit}
+	req := evmtypes.EthCallRequest{Args: bz, GasCap: e.backend.RPCGasCap()}
 
 	// From ContextWithHeight: if the provided height is 0,
 	// it will return an empty context and the gRPC query will use

ethereum/rpc/namespaces/miner/api.go

@@ -9,7 +9,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/client/flags"
 	"github.com/cosmos/cosmos-sdk/client/tx"
 	"github.com/cosmos/cosmos-sdk/server"
-	"github.com/cosmos/cosmos-sdk/server/config"
+	sdkconfig "github.com/cosmos/cosmos-sdk/server/config"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 
 	authtx "github.com/cosmos/cosmos-sdk/x/auth/tx"
@@ -23,6 +23,7 @@ import (
 
 	"github.com/tharsis/ethermint/ethereum/rpc/backend"
 	rpctypes "github.com/tharsis/ethermint/ethereum/rpc/types"
+	"github.com/tharsis/ethermint/server/config"
 )
 
 // API is the miner prefixed set of APIs in the Miner JSON-RPC spec.
@@ -186,7 +187,7 @@ func (api *API) SetGasPrice(gasPrice hexutil.Big) bool {
 	c := sdk.NewDecCoin(unit, sdk.NewIntFromBigInt(gasPrice.ToInt()))
 
 	appConf.SetMinGasPrices(sdk.DecCoins{c})
-	config.WriteConfigFile(api.ctx.Viper.ConfigFileUsed(), appConf)
+	sdkconfig.WriteConfigFile(api.ctx.Viper.ConfigFileUsed(), appConf)
 	api.logger.Info("Your configuration file was modified. Please RESTART your node.", "gas-price", c.String())
 	return true
 }

server/config/config.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"errors"
 	"fmt"
 
 	"github.com/spf13/viper"
@@ -24,6 +25,8 @@ const (
 
 	// DefaultEVMTracer is the default vm.Tracer type
 	DefaultEVMTracer = "json"
+
+	DefaultGasCap uint64 = 25000000
 )
 
 var (
@@ -113,6 +116,27 @@ type JSONRPCConfig struct {
 	Enable bool `mapstructure:"enable"`
 	// EnableUnsafeCORS defines if CORS should be enabled (unsafe - use it at your own risk)
 	EnableUnsafeCORS bool `mapstructure:"enable-unsafe-cors"`
+	// GasCap is the global gas cap for eth-call variants.
+	GasCap uint64 `mapstructure:"gas-cap"`
+}
+
+// Validate returns an error if the JSON-RPC configuration fields are invalid.
+func (c JSONRPCConfig) Validate() error {
+	if c.Enable && len(c.API) == 0 {
+		return errors.New("cannot enable JSON-RPC without defining any API namespace")
+	}
+
+	// TODO: validate APIs
+	seenAPIs := make(map[string]bool)
+	for _, api := range c.API {
+		if seenAPIs[api] {
+			return fmt.Errorf("repeated API namespace '%s'", api)
+		}
+
+		seenAPIs[api] = true
+	}
+
+	return nil
 }
 
 // DefaultJSONRPCConfig returns an EVM config with the JSON-RPC API enabled by default
@@ -123,6 +147,7 @@ func DefaultJSONRPCConfig() *JSONRPCConfig {
 		Address:          DefaultJSONRPCAddress,
 		WsAddress:        DefaultJSONRPCWsAddress,
 		EnableUnsafeCORS: false,
+		GasCap:           DefaultGasCap,
 	}
 }
 
@@ -150,17 +175,29 @@ func GetConfig(v *viper.Viper) Config {
 			Address:          v.GetString("json-rpc.address"),
 			WsAddress:        v.GetString("json-rpc.ws-address"),
 			EnableUnsafeCORS: v.GetBool("json-rpc.enable-unsafe-cors"),
+			GasCap:           v.GetUint64("json-rpc.gas-cap"),
 		},
 	}
 }
 
+// ParseConfig retrieves the default environment configuration for the
+// application.
+func ParseConfig(v *viper.Viper) (*Config, error) {
+	conf := DefaultConfig()
+	err := v.Unmarshal(conf)
+
+	return conf, err
+}
+
 // ValidateBasic returns an error any of the application configuration fields are invalid
 func (c Config) ValidateBasic() error {
 	if err := c.EVM.Validate(); err != nil {
 		return sdkerrors.Wrapf(sdkerrors.ErrAppConfig, "invalid evm config value: %s", err.Error())
 	}
 
-	// TODO: validate JSON-RPC APIs
+	if err := c.JSONRPC.Validate(); err != nil {
+		return sdkerrors.Wrapf(sdkerrors.ErrAppConfig, "invalid json-rpc config value: %s", err.Error())
+	}
 
 	return c.Config.ValidateBasic()
 }

server/config/toml.go

@@ -34,4 +34,7 @@ api = "{{range $index, $elmt := .JSONRPC.API}}{{if $index}},{{$elmt}}{{else}}{{$
 
 # EnableUnsafeCORS defines if CORS should be enabled (unsafe - use it at your own risk)
 enable-unsafe-cors = "{{ .JSONRPC.EnableUnsafeCORS }}"
+
+# GasCap sets a cap on gas that can be used in eth_call/estimateGas (0=infinite). Default: 25,000,000.
+gas-cap = {{ .JSONRPC.GasCap }}
 `

server/flags/flags.go

@@ -31,6 +31,7 @@ const (
 	JSONRPCAddress       = "json-rpc.address"
 	JSONWsAddress        = "json-rpc.ws-address"
 	JSONEnableUnsafeCORS = "json-rpc.enable-unsafe-cors"
+	JSONRPCGasCap        = "json-rpc.gas-cap"
 )
 
 // EVM flags

server/start.go

@@ -143,6 +143,7 @@ which accepts a path for the resulting pprof file.
 	cmd.Flags().String(srvflags.JSONRPCAddress, config.DefaultJSONRPCAddress, "the JSON-RPC server address to listen on")
 	cmd.Flags().String(srvflags.JSONWsAddress, config.DefaultJSONRPCWsAddress, "the JSON-RPC WS server address to listen on")
 	cmd.Flags().Bool(srvflags.JSONEnableUnsafeCORS, false, "Define if the JSON-RPC server should enabled CORS (unsafe - use it at your own risk)")
+	cmd.Flags().Uint64(srvflags.JSONRPCGasCap, config.DefaultGasCap, "Sets a cap on gas that can be used in eth_call/estimateGas (0=infinite)")
 
 	cmd.Flags().String(srvflags.EVMTracer, config.DefaultEVMTracer, "the EVM tracer type to collect execution traces from the EVM transaction execution (json|struct|access_list|markdown)")
 

types/params.go

@@ -1,8 +0,0 @@
-package types
-
-const (
-	// DefaultGasPrice is default gas price for evm transactions
-	DefaultGasPrice = 20
-	// DefaultRPCGasLimit is default gas limit for RPC call operations
-	DefaultRPCGasLimit = 10000000
-)

x/evm/keeper/grpc_query_test.go

@@ -724,7 +724,7 @@ func (suite *KeeperTestSuite) deployTestContract(owner common.Address, supply *b
 
 	res, err := suite.queryClient.EstimateGas(ctx, &types.EthCallRequest{
 		Args:   args,
-		GasCap: uint64(ethermint.DefaultRPCGasLimit),
+		GasCap: 25_000_000,
 	})
 	suite.Require().NoError(err)
 
@@ -805,7 +805,7 @@ func (suite *KeeperTestSuite) TestEstimateGas() {
 	for _, tc := range testCases {
 		suite.Run(fmt.Sprintf("Case %s", tc.msg), func() {
 			suite.SetupTest()
-			gasCap = ethermint.DefaultRPCGasLimit
+			gasCap = 25_000_000
 			tc.malleate()
 
 			args, err := json.Marshal(&args)