cmd/utils: fix disabling discovery through config file (ethereum#33279)

No matter what value of P2P.DiscoveryV4 or DiscoveryV5 is set in config file,
it will be overwritten by the CLI flag, even if the flag is not set. This fixes it
to apply the flag only if set.

Author: cuiweixie

cmd/utils/flags.go

@@ -864,14 +864,14 @@ var (
 		Aliases:  []string{"discv4"},
 		Usage:    "Enables the V4 discovery mechanism",
 		Category: flags.NetworkingCategory,
-		Value:    true,
+		Value:    node.DefaultConfig.P2P.DiscoveryV4,
 	}
 	DiscoveryV5Flag = &cli.BoolFlag{
 		Name:     "discovery.v5",
 		Aliases:  []string{"discv5"},
 		Usage:    "Enables the V5 discovery mechanism",
 		Category: flags.NetworkingCategory,
-		Value:    true,
+		Value:    node.DefaultConfig.P2P.DiscoveryV5,
 	}
 	NetrestrictFlag = &cli.StringFlag{
 		Name:     "netrestrict",
@@ -1373,8 +1373,12 @@ func SetP2PConfig(ctx *cli.Context, cfg *p2p.Config) {
 
 	flags.CheckExclusive(ctx, DiscoveryV4Flag, NoDiscoverFlag)
 	flags.CheckExclusive(ctx, DiscoveryV5Flag, NoDiscoverFlag)
-	cfg.DiscoveryV4 = ctx.Bool(DiscoveryV4Flag.Name)
-	cfg.DiscoveryV5 = ctx.Bool(DiscoveryV5Flag.Name)
+	if ctx.IsSet(DiscoveryV4Flag.Name) {
+		cfg.DiscoveryV4 = ctx.Bool(DiscoveryV4Flag.Name)
+	}
+	if ctx.IsSet(DiscoveryV5Flag.Name) {
+		cfg.DiscoveryV5 = ctx.Bool(DiscoveryV5Flag.Name)
+	}
 
 	if netrestrict := ctx.String(NetrestrictFlag.Name); netrestrict != "" {
 		list, err := netutil.ParseNetlist(netrestrict)

node/defaults.go

@@ -69,9 +69,11 @@ var DefaultConfig = Config{
 	BatchResponseMaxSize: 25 * 1000 * 1000,
 	GraphQLVirtualHosts:  []string{"localhost"},
 	P2P: p2p.Config{
-		ListenAddr: ":30303",
-		MaxPeers:   50,
-		NAT:        nat.Any(),
+		ListenAddr:  ":30303",
+		MaxPeers:    50,
+		NAT:         nat.Any(),
+		DiscoveryV4: true,
+		DiscoveryV5: true,
 	},
 	DBEngine: "", // Use whatever exists, will default to Pebble if non-existent and supported
 }