cmd/geth: add --config file flag (#13875)

* p2p/discover, p2p/discv5: add marshaling methods to Node

* p2p/netutil: make Netlist decodable from TOML

* common/math: encode nil HexOrDecimal256 as 0x0

* cmd/geth: add --config file flag

* cmd/geth: add missing license header

* eth: prettify Config again, fix tests

* eth: use gasprice.Config instead of duplicating its fields

* eth/gasprice: hide nil default from dumpconfig output

* cmd/geth: hide genesis block in dumpconfig output

* node: make tests compile

* console: fix tests

* cmd/geth: make TOML keys look exactly like Go struct fields

* p2p: use discovery by default

This makes the zero Config slightly more useful. It also fixes package
node tests because Node detects reuse of the datadir through the
NodeDatabase.

* cmd/geth: make ethstats URL settable through config file

* cmd/faucet: fix configuration

* cmd/geth: dedup attach tests

* eth: add comment for DefaultConfig

* eth: pass downloader.SyncMode in Config

This removes the FastSync, LightSync flags in favour of a more
general SyncMode flag.

* cmd/utils: remove jitvm flags

* cmd/utils: make mutually exclusive flag error prettier

It now reads:

   Fatal: flags --dev, --testnet can't be used at the same time

* p2p: fix typo

* node: add DefaultConfig, use it for geth

* mobile: add missing NoDiscovery option

* cmd/utils: drop MakeNode

This exposed a couple of places that needed to be updated to use
node.DefaultConfig.

* node: fix typo

* eth: make fast sync the default mode

* cmd/utils: remove IPCApiFlag (unused)

* node: remove default IPC path

Set it in the frontends instead.

* cmd/geth: add --syncmode

* cmd/utils: make --ipcdisable and --ipcpath mutually exclusive

* cmd/utils: don't enable WS, HTTP when setting addr

* cmd/utils: fix --identity

mobile/geth.go

@@ -22,15 +22,16 @@ package geth
 import (
 	"encoding/json"
 	"fmt"
-	"math/big"
 	"path/filepath"
 
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/eth"
+	"github.com/ethereum/go-ethereum/eth/downloader"
 	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/ethereum/go-ethereum/ethstats"
 	"github.com/ethereum/go-ethereum/les"
 	"github.com/ethereum/go-ethereum/node"
+	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/nat"
 	"github.com/ethereum/go-ethereum/params"
 	whisper "github.com/ethereum/go-ethereum/whisper/whisperv2"
@@ -108,17 +109,19 @@ func NewNode(datadir string, config *NodeConfig) (stack *Node, _ error) {
 	}
 	// Create the empty networking stack
 	nodeConf := &node.Config{
-		Name:             clientIdentifier,
-		Version:          params.Version,
-		DataDir:          datadir,
-		KeyStoreDir:      filepath.Join(datadir, "keystore"), // Mobile should never use internal keystores!
-		NoDiscovery:      true,
-		DiscoveryV5:      true,
-		DiscoveryV5Addr:  ":0",
-		BootstrapNodesV5: config.BootstrapNodes.nodes,
-		ListenAddr:       ":0",
-		NAT:              nat.Any(),
-		MaxPeers:         config.MaxPeers,
+		Name:        clientIdentifier,
+		Version:     params.Version,
+		DataDir:     datadir,
+		KeyStoreDir: filepath.Join(datadir, "keystore"), // Mobile should never use internal keystores!
+		P2P: p2p.Config{
+			NoDiscovery:      true,
+			DiscoveryV5:      true,
+			DiscoveryV5Addr:  ":0",
+			BootstrapNodesV5: config.BootstrapNodes.nodes,
+			ListenAddr:       ":0",
+			NAT:              nat.Any(),
+			MaxPeers:         config.MaxPeers,
+		},
 	}
 	rawStack, err := node.New(nodeConf)
 	if err != nil {
@@ -142,20 +145,13 @@ func NewNode(datadir string, config *NodeConfig) (stack *Node, _ error) {
 	}
 	// Register the Ethereum protocol if requested
 	if config.EthereumEnabled {
-		ethConf := &eth.Config{
-			Genesis:            genesis,
-			LightMode:          true,
-			DatabaseCache:      config.EthereumDatabaseCache,
-			NetworkId:          config.EthereumNetworkID,
-			GasPrice:           new(big.Int).SetUint64(20 * params.Shannon),
-			GpoBlocks:          10,
-			GpoPercentile:      50,
-			EthashCacheDir:     "ethash",
-			EthashCachesInMem:  2,
-			EthashCachesOnDisk: 3,
-		}
+		ethConf := eth.DefaultConfig
+		ethConf.Genesis = genesis
+		ethConf.SyncMode = downloader.LightSync
+		ethConf.NetworkId = config.EthereumNetworkID
+		ethConf.DatabaseCache = config.EthereumDatabaseCache
 		if err := rawStack.Register(func(ctx *node.ServiceContext) (node.Service, error) {
-			return les.New(ctx, ethConf)
+			return les.New(ctx, &ethConf)
 		}); err != nil {
 			return nil, fmt.Errorf("ethereum init: %v", err)
 		}