cmd/geth: add some DNS flags

cmd/geth/main.go

@@ -131,6 +131,7 @@ var (
 		utils.NetrestrictFlag,
 		utils.NodeKeyFileFlag,
 		utils.NodeKeyHexFlag,
+		utils.DisableDNSFlag,
 		utils.DeveloperFlag,
 		utils.DeveloperPeriodFlag,
 		utils.TestnetFlag,

cmd/geth/usage.go

@@ -191,6 +191,7 @@ var AppHelpFlagGroups = []flagGroup{
 			utils.NetrestrictFlag,
 			utils.NodeKeyFileFlag,
 			utils.NodeKeyHexFlag,
+			utils.DisableDNSFlag,
 		},
 	},
 	{

cmd/utils/flags.go

@@ -658,6 +658,10 @@ var (
 		Name:  "netrestrict",
 		Usage: "Restricts network communication to the given IP networks (CIDR masks)",
 	}
+	DisableDNSFlag = cli.BoolFlag{
+		Name:  "nodns",
+		Usage: "disables DNS-based node discovery",
+	}
 
 	// ATM the url is left to the user and deployment to
 	JSpathFlag = cli.StringFlag{
@@ -1477,6 +1481,9 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *eth.Config) {
 	if ctx.GlobalIsSet(RPCGlobalGasCap.Name) {
 		cfg.RPCGasCap = new(big.Int).SetUint64(ctx.GlobalUint64(RPCGlobalGasCap.Name))
 	}
+	if ctx.GlobalIsSet(DisableDNSFlag.Name) {
+		cfg.DisableDNSDiscovery = ctx.GlobalBool(DisableDNSFlag.Name)
+	}
 
 	// Override any default configs for hard coded networks.
 	switch {