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, 21 insertions, 5 deletions

diff --git a/node/defaults.go b/node/defaults.go
index bfe257c8e..d4e148683 100644
--- a/node/defaults.go
+++ b/node/defaults.go
@@ -21,16 +21,32 @@ import (
 	"os/user"
 	"path/filepath"
 	"runtime"
+
+	"github.com/ethereum/go-ethereum/p2p"
+	"github.com/ethereum/go-ethereum/p2p/nat"
 )
 
 const (
-	DefaultIPCSocket = "geth.ipc"  // Default (relative) name of the IPC RPC socket
-	DefaultHTTPHost  = "localhost" // Default host interface for the HTTP RPC server
-	DefaultHTTPPort  = 8545        // Default TCP port for the HTTP RPC server
-	DefaultWSHost    = "localhost" // Default host interface for the websocket RPC server
-	DefaultWSPort    = 8546        // Default TCP port for the websocket RPC server
+	DefaultHTTPHost = "localhost" // Default host interface for the HTTP RPC server
+	DefaultHTTPPort = 8545        // Default TCP port for the HTTP RPC server
+	DefaultWSHost   = "localhost" // Default host interface for the websocket RPC server
+	DefaultWSPort   = 8546        // Default TCP port for the websocket RPC server
 )
 
+// DefaultConfig contains reasonable default settings.
+var DefaultConfig = Config{
+	DataDir:     DefaultDataDir(),
+	HTTPPort:    DefaultHTTPPort,
+	HTTPModules: []string{"net", "web3"},
+	WSPort:      DefaultWSPort,
+	WSModules:   []string{"net", "web3"},
+	P2P: p2p.Config{
+		ListenAddr: ":30303",
+		MaxPeers:   25,
+		NAT:        nat.Any(),
+	},
+}
+
 // DefaultDataDir is the default data directory to use for the databases and other
 // persistence requirements.
 func DefaultDataDir() string {