Implement eth_pendingTransactions, bump sdk version (#124)

* Update sdk version, implement pending txs, fix nonce check

* Bump cached dependencies in circleCI

* bump circleci go version

* updated linter and fixed bugs relating to go version 1.13

x/evm/handler.go

@@ -64,7 +64,7 @@ func handleETHTxMsg(ctx sdk.Context, keeper Keeper, msg types.EthereumTxMsg) sdk
 		Recipient:    msg.Data.Recipient,
 		Amount:       msg.Data.Amount,
 		Payload:      msg.Data.Payload,
-		Csdb:         keeper.csdb,
+		Csdb:         keeper.csdb.WithContext(ctx),
 		ChainID:      intChainID,
 		THash:        &ethHash,
 	}
@@ -95,7 +95,7 @@ func handleEmintMsg(ctx sdk.Context, keeper Keeper, msg types.EmintMsg) sdk.Resu
 		GasLimit:     msg.GasLimit,
 		Amount:       msg.Amount.BigInt(),
 		Payload:      msg.Payload,
-		Csdb:         keeper.csdb,
+		Csdb:         keeper.csdb.WithContext(ctx),
 		ChainID:      intChainID,
 	}
 

x/evm/types/state_transition.go

@@ -31,6 +31,10 @@ type StateTransition struct {
 func (st StateTransition) TransitionCSDB(ctx sdk.Context) (sdk.Result, *big.Int) {
 	contractCreation := st.Recipient == nil
 
+	if res := st.checkNonce(); !res.IsOK() {
+		return res, nil
+	}
+
 	// This gas limit the the transaction gas limit with intrinsic gas subtracted
 	gasLimit := ctx.GasMeter().Limit()
 
@@ -97,3 +101,15 @@ func (st StateTransition) TransitionCSDB(ctx sdk.Context) (sdk.Result, *big.Int)
 
 	return sdk.Result{Data: returnData, GasUsed: st.GasLimit - leftOverGas}, bloomInt
 }
+
+func (st *StateTransition) checkNonce() sdk.Result {
+	// Make sure this transaction's nonce is correct.
+	nonce := st.Csdb.GetNonce(st.Sender)
+	if nonce < st.AccountNonce {
+		return emint.ErrInvalidNonce("nonce too high").Result()
+	} else if nonce > st.AccountNonce {
+		return emint.ErrInvalidNonce("nonce too low").Result()
+	}
+
+	return sdk.Result{}
+}