Implement eth_sendTransaction (#104)

* Set up framework for sending transaction with correct args and nonce mutex locking

* Set up printing ethereum address through emintkeys and getting chainid from flags

* Implemented defaults for eth_sendTransaction

* Fix bug with no data provided

* Updated comments and error, as well as RLP encoded tx bytes for return instead of amino encoded

x/evm/types/msg.go

@@ -1,6 +1,7 @@
 package types
 
 import (
+	"bytes"
 	"crypto/ecdsa"
 	"errors"
 	"fmt"
@@ -10,8 +11,11 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
+	"github.com/cosmos/ethermint/rpc/args"
 	"github.com/cosmos/ethermint/types"
 
+	"github.com/cosmos/cosmos-sdk/client/context"
 	ethcmn "github.com/ethereum/go-ethereum/common"
 	ethtypes "github.com/ethereum/go-ethereum/core/types"
 	ethcrypto "github.com/ethereum/go-ethereum/crypto"
@@ -355,3 +359,60 @@ func recoverEthSig(R, S, Vb *big.Int, sigHash ethcmn.Hash) (ethcmn.Address, erro
 
 	return addr, nil
 }
+
+// PopulateFromArgs populates tx message with args (used in RPC API)
+func GenerateFromArgs(args args.SendTxArgs, ctx context.CLIContext) (msg *EthereumTxMsg, err error) {
+	var nonce uint64
+
+	var gasLimit uint64
+
+	amount := (*big.Int)(args.Value)
+
+	gasPrice := (*big.Int)(args.GasPrice)
+
+	if args.GasPrice == nil {
+		// Set default gas price
+		// TODO: Change to min gas price from context once available through server/daemon
+		gasPrice = big.NewInt(20)
+	}
+
+	if args.Nonce == nil {
+		// Get nonce (sequence) from account
+		from := sdk.AccAddress(args.From.Bytes())
+		_, nonce, err = authtypes.NewAccountRetriever(ctx).GetAccountNumberSequence(from)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		nonce = (uint64)(*args.Nonce)
+	}
+
+	if args.Data != nil && args.Input != nil && !bytes.Equal(*args.Data, *args.Input) {
+		return nil, fmt.Errorf(`both "data" and "input" are set and not equal. Please use "input" to pass transaction call data`)
+	}
+
+	// Sets input to either Input or Data, if both are set and not equal error above returns
+	var input []byte
+	if args.Input != nil {
+		input = *args.Input
+	} else if args.Data != nil {
+		input = *args.Data
+	}
+
+	if args.To == nil {
+		// Contract creation
+		if len(input) == 0 {
+			return nil, fmt.Errorf("contract creation without any data provided")
+		}
+	}
+
+	if args.Gas == nil {
+		// Estimate the gas usage if necessary.
+		// TODO: Set gas based on estimate when simulating txs are setup
+		gasLimit = 22000
+	} else {
+		gasLimit = (uint64)(*args.Gas)
+	}
+
+	return newEthereumTxMsg(nonce, args.To, amount, gasLimit, gasPrice, input), nil
+}