Extend the genesis.json to include clique initial signers (#37)

cmd/utils/flags.go

@@ -31,6 +31,7 @@ import (
 	"os"
 	"path/filepath"
 	godebug "runtime/debug"
+	"sort"
 	"strconv"
 	"strings"
 	"time"
@@ -2258,16 +2259,69 @@ func MakeConsolePreloads(ctx *cli.Context) []string {
 	return preloads
 }
 
+// jsonGenesis is an extension over the traditional Geth genesis file
+type jsonGenesis struct {
+	core *core.Genesis `json:"-"`
+
+	Config struct {
+		Clique struct {
+			// Signers is the list of initial validators of the clique protocol
+			InitialSigners []string `json:"initial_signers"`
+		} `json:"clique,omitempty"`
+	} `json:"config"`
+}
+
+func readJSONGenesis(genesisPath string) (*jsonGenesis, error) {
+	genesisRaw, err := os.ReadFile(genesisPath)
+	if err != nil {
+		return nil, err
+	}
+
+	coreGenesis := new(core.Genesis)
+	if err := json.Unmarshal(genesisRaw, coreGenesis); err != nil {
+		return nil, fmt.Errorf("invalid genesis file: %v", err)
+	}
+
+	genesis := new(jsonGenesis)
+	if err := json.Unmarshal(genesisRaw, genesis); err != nil {
+		return nil, fmt.Errorf("invalid genesis file: %v", err)
+	}
+
+	genesis.core = coreGenesis
+	return genesis, nil
+}
+
 // initCustomGenesis is a simplified version of the initGenesis command
 func initCustomGenesis(ctx *cli.Context, stack *node.Node, genesisPath string) (*core.Genesis, common.Hash, error) {
-	genesisRaw, err := os.ReadFile(genesisPath)
+	genesis, err := readJSONGenesis(genesisPath)
 	if err != nil {
 		return nil, common.Hash{}, err
 	}
 
-	genesis := new(core.Genesis)
-	if err := json.Unmarshal(genesisRaw, genesis); err != nil {
-		return nil, common.Hash{}, fmt.Errorf("invalid genesis file: %v", err)
+	// if we are running Clique, read the initial validator set from the Config.Clique.Signers path
+	// and build the extra genesis data as [(32 byte), signer1, signer2, (65 byte)] where the
+	// signers are sorted by their address
+	if genesis.core.Config.Clique != nil {
+		signersStr := genesis.Config.Clique.InitialSigners
+		if len(signersStr) == 0 {
+			return nil, common.Hash{}, fmt.Errorf("no initial signers for Clique")
+		}
+
+		signers := make([]common.Address, len(signersStr))
+		for i, signerStr := range signersStr {
+			signers[i] = common.HexToAddress(signerStr)
+		}
+
+		sort.Slice(signers, func(i, j int) bool {
+			return bytes.Compare(signers[i][:], signers[j][:]) < 0
+		})
+
+		extra := make([]byte, 32)
+		for _, addr := range signers {
+			extra = append(extra, addr.Bytes()...)
+		}
+		extra = append(extra, make([]byte, 65)...)
+		genesis.core.ExtraData = extra
 	}
 
 	chaindb, err := stack.OpenDatabaseWithFreezer("chaindata", 0, 0, ctx.String(AncientFlag.Name), "", false)
@@ -2277,12 +2331,12 @@ func initCustomGenesis(ctx *cli.Context, stack *node.Node, genesisPath string) (
 	triedb := trie.NewDatabaseWithConfig(chaindb, &trie.Config{
 		Preimages: false,
 	})
-	_, hash, err := core.SetupGenesisBlock(chaindb, triedb, genesis)
+	_, hash, err := core.SetupGenesisBlock(chaindb, triedb, genesis.core)
 	if err != nil {
 		return nil, common.Hash{}, err
 	}
 	chaindb.Close()
 
 	log.Info("Successfully wrote genesis state", "database", "chaindata", "hash", hash)
-	return genesis, hash, nil
+	return genesis.core, hash, nil
 }