chaincmd: correctly create consortium engine in import chain

Currently, when import chain is used, we don't recognize the chain config to
create the consortium engine. This commit creates the consortium engine when it
is set in the chain config.

cmd/utils/flags.go

@@ -39,6 +39,7 @@ import (
 	"github.com/ethereum/go-ethereum/common/fdlimit"
 	"github.com/ethereum/go-ethereum/consensus"
 	"github.com/ethereum/go-ethereum/consensus/clique"
+	"github.com/ethereum/go-ethereum/consensus/consortium"
 	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/rawdb"
@@ -2036,9 +2037,17 @@ func MakeChain(ctx *cli.Context, stack *node.Node) (chain *core.BlockChain, chai
 	if err != nil {
 		Fatalf("%v", err)
 	}
-	var engine consensus.Engine
+	var (
+		engine        consensus.Engine
+		setBlockChain func(chain *core.BlockChain)
+		ethApiBackend *eth.EthAPIBackend
+	)
 	if config.Clique != nil {
 		engine = clique.New(config.Clique, chainDb)
+	} else if config.Consortium != nil {
+		ethApiBackend, setBlockChain = eth.MakeEthApiBackend(chainDb)
+		ethApi := ethapi.NewPublicBlockChainAPI(ethApiBackend)
+		engine = consortium.New(config, chainDb, ethApi)
 	} else {
 		engine = ethash.NewFaker()
 		if !ctx.GlobalBool(FakePoWFlag.Name) {
@@ -2087,6 +2096,7 @@ func MakeChain(ctx *cli.Context, stack *node.Node) (chain *core.BlockChain, chai
 	if err != nil {
 		Fatalf("Can't create BlockChain: %v", err)
 	}
+	setBlockChain(chain)
 	return chain, chainDb
 }
 

eth/backend.go

@@ -351,6 +351,22 @@ func New(stack *node.Node, config *ethconfig.Config) (*Ethereum, error) {
 	return eth, nil
 }
 
+// MakeEthApiBackend is used by MakeChain to create a minimal eth API backend for consortium
+// engine.
+// This code looks hacky as it returns a function to set the private blockchain field. This is
+// due to the circular dependency as blockchain needs consortium engine which requires
+// eth API backend. As the eth API backend is not used right after being created, we create a
+// eth API backend without blockchain here and set that field later when blockchain is available.
+func MakeEthApiBackend(chainDb ethdb.Database) (*EthAPIBackend, func(chain *core.BlockChain)) {
+	eth := &Ethereum{
+		chainDb: chainDb,
+	}
+	apiBackend := &EthAPIBackend{eth: eth}
+	return apiBackend, func(chain *core.BlockChain) {
+		eth.blockchain = chain
+	}
+}
+
 func makeExtraData(extra []byte) []byte {
 	if len(extra) == 0 {
 		// create default extradata