rpc: add BlockByHash to Client (#4923)

Ethermint currently has to maintain a map height-> block hash on the store (see here) as it needs to expose the eth_getBlockByHash JSON-RPC query for Web3 compatibility. This query is currently not supported by the tendermint RPC client.

rpc/client/http/http.go

@@ -367,6 +367,18 @@ func (c *baseRPCClient) Block(height *int64) (*ctypes.ResultBlock, error) {
 	return result, nil
 }
 
+func (c *baseRPCClient) BlockByHash(hash []byte) (*ctypes.ResultBlock, error) {
+	result := new(ctypes.ResultBlock)
+	params := map[string]interface{}{
+		"hash": hash,
+	}
+	_, err := c.caller.Call("block_by_hash", params, result)
+	if err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
 func (c *baseRPCClient) BlockResults(height *int64) (*ctypes.ResultBlockResults, error) {
 	result := new(ctypes.ResultBlockResults)
 	params := make(map[string]interface{})

rpc/client/interface.go

@@ -65,6 +65,7 @@ type ABCIClient interface {
 // and prove anything about the chain.
 type SignClient interface {
 	Block(height *int64) (*ctypes.ResultBlock, error)
+	BlockByHash(hash []byte) (*ctypes.ResultBlock, error)
 	BlockResults(height *int64) (*ctypes.ResultBlockResults, error)
 	Commit(height *int64) (*ctypes.ResultCommit, error)
 	Validators(height *int64, page, perPage int) (*ctypes.ResultValidators, error)

rpc/client/local/local.go

@@ -144,6 +144,10 @@ func (c *Local) Block(height *int64) (*ctypes.ResultBlock, error) {
 	return core.Block(c.ctx, height)
 }
 
+func (c *Local) BlockByHash(hash []byte) (*ctypes.ResultBlock, error) {
+	return core.BlockByHash(c.ctx, hash)
+}
+
 func (c *Local) BlockResults(height *int64) (*ctypes.ResultBlockResults, error) {
 	return core.BlockResults(c.ctx, height)
 }

rpc/client/mock/client.go

@@ -150,6 +150,10 @@ func (c Client) Block(height *int64) (*ctypes.ResultBlock, error) {
 	return core.Block(&rpctypes.Context{}, height)
 }
 
+func (c Client) BlockByHash(hash []byte) (*ctypes.ResultBlock, error) {
+	return core.BlockByHash(&rpctypes.Context{}, hash)
+}
+
 func (c Client) Commit(height *int64) (*ctypes.ResultCommit, error) {
 	return core.Commit(&rpctypes.Context{}, height)
 }

rpc/client/rpc_test.go

@@ -249,6 +249,10 @@ func TestAppCalls(t *testing.T) {
 		assert.True(len(appHash) > 0)
 		assert.EqualValues(apph, block.Block.Header.Height)
 
+		blockByHash, err := c.BlockByHash(block.BlockID.Hash)
+		require.NoError(err)
+		require.Equal(block, blockByHash)
+
 		// now check the results
 		blockResults, err := c.BlockResults(&txh)
 		require.Nil(err, "%d: %+v", i, err)