cmd/faucet: enable DNS discovery for known networks (#21636)

cmd/faucet/faucet.go

@@ -43,6 +43,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/accounts/keystore"
+	"github.com/ethereum/go-ethereum/cmd/utils"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -241,6 +242,7 @@ func newFaucet(genesis *core.Genesis, port int, enodes []*discv5.Node, network u
 	cfg.SyncMode = downloader.LightSync
 	cfg.NetworkId = network
 	cfg.Genesis = genesis
+	utils.SetDNSDiscoveryDefaults(&cfg, genesis.ToBlock(nil).Hash())
 	lesBackend, err := les.New(stack, &cfg)
 	if err != nil {
 		return nil, fmt.Errorf("Failed to register the Ethereum service: %w", err)

cmd/utils/flags.go

@@ -1590,19 +1590,19 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *eth.Config) {
 			cfg.NetworkId = 3
 		}
 		cfg.Genesis = core.DefaultRopstenGenesisBlock()
-		setDNSDiscoveryDefaults(cfg, params.RopstenGenesisHash)
+		SetDNSDiscoveryDefaults(cfg, params.RopstenGenesisHash)
 	case ctx.GlobalBool(RinkebyFlag.Name):
 		if !ctx.GlobalIsSet(NetworkIdFlag.Name) {
 			cfg.NetworkId = 4
 		}
 		cfg.Genesis = core.DefaultRinkebyGenesisBlock()
-		setDNSDiscoveryDefaults(cfg, params.RinkebyGenesisHash)
+		SetDNSDiscoveryDefaults(cfg, params.RinkebyGenesisHash)
 	case ctx.GlobalBool(GoerliFlag.Name):
 		if !ctx.GlobalIsSet(NetworkIdFlag.Name) {
 			cfg.NetworkId = 5
 		}
 		cfg.Genesis = core.DefaultGoerliGenesisBlock()
-		setDNSDiscoveryDefaults(cfg, params.GoerliGenesisHash)
+		SetDNSDiscoveryDefaults(cfg, params.GoerliGenesisHash)
 	case ctx.GlobalBool(YoloV1Flag.Name):
 		if !ctx.GlobalIsSet(NetworkIdFlag.Name) {
 			cfg.NetworkId = 133519467574833 // "yolov1"
@@ -1656,14 +1656,14 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *eth.Config) {
 		}
 	default:
 		if cfg.NetworkId == 1 {
-			setDNSDiscoveryDefaults(cfg, params.MainnetGenesisHash)
+			SetDNSDiscoveryDefaults(cfg, params.MainnetGenesisHash)
 		}
 	}
 }
 
-// setDNSDiscoveryDefaults configures DNS discovery with the given URL if
+// SetDNSDiscoveryDefaults configures DNS discovery with the given URL if
 // no URLs are set.
-func setDNSDiscoveryDefaults(cfg *eth.Config, genesis common.Hash) {
+func SetDNSDiscoveryDefaults(cfg *eth.Config, genesis common.Hash) {
 	if cfg.DiscoveryURLs != nil {
 		return // already set through flags/config
 	}