From 988ee53a59311c4d436188853e7d1ff3c57bc19f Mon Sep 17 00:00:00 2001
From: Federico Kunze <31522760+fedekunze@users.noreply.github.com>
Date: Mon, 8 Jun 2020 18:43:37 +0200
Subject: [PATCH] rpc: implement eth_coinbase (#325)

* rpc: implement eth_coinbase

* changelog

* address comments from review

* changelog
---
 CHANGELOG.md      |  1 +
 rpc/backend.go    |  4 +++-
 rpc/eth_api.go    | 16 +++++++++++++---
 tests/rpc_test.go | 12 ++++++++++++
 4 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5ee10056..d091783f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -61,6 +61,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
   * Remove evm `CodeKey` and `BlockKey`in favor of a prefix `Store`.
   * Set `BlockBloom` during `EndBlock` instead of `BeginBlock`.
   * `Commit` state object and `Finalize` storage after `InitGenesis` setup.
+* (rpc) [\#325](https://github.com/ChainSafe/ethermint/pull/325) `eth_coinbase` JSON-RPC query now returns the node's validator address.
 
 ### Features
 
diff --git a/rpc/backend.go b/rpc/backend.go
index 9362745c..41a1b7a3 100644
--- a/rpc/backend.go
+++ b/rpc/backend.go
@@ -47,13 +47,15 @@ func NewEthermintBackend(cliCtx context.CLIContext) *EthermintBackend {
 
 // BlockNumber returns the current block number.
 func (e *EthermintBackend) BlockNumber() (hexutil.Uint64, error) {
-	res, _, err := e.cliCtx.QueryWithData(fmt.Sprintf("custom/%s/blockNumber", types.ModuleName), nil)
+	res, height, err := e.cliCtx.QueryWithData(fmt.Sprintf("custom/%s/blockNumber", types.ModuleName), nil)
 	if err != nil {
 		return hexutil.Uint64(0), err
 	}
 
 	var out types.QueryResBlockNumber
 	e.cliCtx.Codec.MustUnmarshalJSON(res, &out)
+
+	e.cliCtx.WithHeight(height)
 	return hexutil.Uint64(out.Number), nil
 }
 
diff --git a/rpc/eth_api.go b/rpc/eth_api.go
index fc783714..170b12e5 100644
--- a/rpc/eth_api.go
+++ b/rpc/eth_api.go
@@ -90,9 +90,19 @@ func (e *PublicEthAPI) Syncing() (interface{}, error) {
 	}, nil
 }
 
-// Coinbase returns this node's coinbase address. Not used in Ethermint.
-func (e *PublicEthAPI) Coinbase() (addr common.Address) {
-	return
+// Coinbase is the address that staking rewards will be send to (alias for Etherbase).
+func (e *PublicEthAPI) Coinbase() (common.Address, error) {
+	node, err := e.cliCtx.GetNode()
+	if err != nil {
+		return common.Address{}, err
+	}
+
+	status, err := node.Status()
+	if err != nil {
+		return common.Address{}, err
+	}
+
+	return common.BytesToAddress(status.ValidatorInfo.Address.Bytes()), nil
 }
 
 // Mining returns whether or not this node is currently mining. Always false.
diff --git a/tests/rpc_test.go b/tests/rpc_test.go
index 8ccfe46e..7b556292 100644
--- a/tests/rpc_test.go
+++ b/tests/rpc_test.go
@@ -139,6 +139,18 @@ func TestEth_blockNumber(t *testing.T) {
 	t.Logf("Got block number: %s\n", res.String())
 }
 
+func TestEth_coinbase(t *testing.T) {
+	zeroAddress := hexutil.Bytes(ethcmn.Address{}.Bytes())
+	rpcRes := call(t, "eth_coinbase", []string{})
+
+	var res hexutil.Bytes
+	err := res.UnmarshalJSON(rpcRes.Result)
+	require.NoError(t, err)
+
+	t.Logf("Got coinbase block proposer: %s\n", res.String())
+	require.NotEqual(t, zeroAddress.String(), res.String(), "expected: %s got: %s\n", zeroAddress.String(), res.String())
+}
+
 func TestEth_GetBalance(t *testing.T) {
 	rpcRes := call(t, "eth_getBalance", []string{addrA, zeroString})