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

1 files changed, 117 insertions, 0 deletions

diff --git a/eth/config.go b/eth/config.go
new file mode 100644
index 000000000..9c3f8b0fb
--- /dev/null
+++ b/eth/config.go
@@ -0,0 +1,117 @@
+// Copyright 2014 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package eth
+
+import (
+	"math/big"
+	"os"
+	"os/user"
+	"path/filepath"
+	"runtime"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/eth/downloader"
+	"github.com/ethereum/go-ethereum/eth/gasprice"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+// DefaultConfig contains default settings for use on the Ethereum main net.
+var DefaultConfig = Config{
+	SyncMode:             downloader.FastSync,
+	EthashCachesInMem:    2,
+	EthashCachesOnDisk:   3,
+	EthashDatasetsInMem:  1,
+	EthashDatasetsOnDisk: 2,
+	NetworkId:            1,
+	LightPeers:           20,
+	DatabaseCache:        128,
+	GasPrice:             big.NewInt(20 * params.Shannon),
+
+	GPO: gasprice.Config{
+		Blocks:     10,
+		Percentile: 50,
+	},
+}
+
+func init() {
+	home := os.Getenv("HOME")
+	if home == "" {
+		if user, err := user.Current(); err == nil {
+			home = user.HomeDir
+		}
+	}
+	if runtime.GOOS == "windows" {
+		DefaultConfig.EthashDatasetDir = filepath.Join(home, "AppData", "Ethash")
+	} else {
+		DefaultConfig.EthashDatasetDir = filepath.Join(home, ".ethash")
+	}
+}
+
+//go:generate gencodec -type Config -field-override configMarshaling -formats toml -out gen_config.go
+
+type Config struct {
+	// The genesis block, which is inserted if the database is empty.
+	// If nil, the Ethereum main net block is used.
+	Genesis *core.Genesis `toml:",omitempty"`
+
+	// Protocol options
+	NetworkId int // Network ID to use for selecting peers to connect to
+	SyncMode  downloader.SyncMode
+
+	// Light client options
+	LightServ  int `toml:",omitempty"` // Maximum percentage of time allowed for serving LES requests
+	LightPeers int `toml:",omitempty"` // Maximum number of LES client peers
+	MaxPeers   int `toml:"-"`          // Maximum number of global peers
+
+	// Database options
+	SkipBcVersionCheck bool `toml:"-"`
+	DatabaseHandles    int  `toml:"-"`
+	DatabaseCache      int
+
+	// Mining-related options
+	Etherbase    common.Address `toml:",omitempty"`
+	MinerThreads int            `toml:",omitempty"`
+	ExtraData    []byte         `toml:",omitempty"`
+	GasPrice     *big.Int
+
+	// Ethash options
+	EthashCacheDir       string
+	EthashCachesInMem    int
+	EthashCachesOnDisk   int
+	EthashDatasetDir     string
+	EthashDatasetsInMem  int
+	EthashDatasetsOnDisk int
+
+	// Gas Price Oracle options
+	GPO gasprice.Config
+
+	// Enables tracking of SHA3 preimages in the VM
+	EnablePreimageRecording bool
+
+	// Miscellaneous options
+	SolcPath  string
+	DocRoot   string `toml:"-"`
+	PowFake   bool   `toml:"-"`
+	PowTest   bool   `toml:"-"`
+	PowShared bool   `toml:"-"`
+}
+
+type configMarshaling struct {
+	ExtraData hexutil.Bytes
+}