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, 20 insertions, 71 deletions

diff --git a/node/config.go b/node/config.go
index b060b05f2..7c17e707d 100644
--- a/node/config.go
+++ b/node/config.go
@@ -20,7 +20,6 @@ import (
 	"crypto/ecdsa"
 	"fmt"
 	"io/ioutil"
-	"net"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -32,10 +31,8 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/discover"
-	"github.com/ethereum/go-ethereum/p2p/discv5"
-	"github.com/ethereum/go-ethereum/p2p/nat"
-	"github.com/ethereum/go-ethereum/p2p/netutil"
 )
 
 var (
@@ -53,14 +50,14 @@ type Config struct {
 	// Name sets the instance name of the node. It must not contain the / character and is
 	// used in the devp2p node identifier. The instance name of geth is "geth". If no
 	// value is specified, the basename of the current executable is used.
-	Name string
+	Name string `toml:"-"`
 
 	// UserIdent, if set, is used as an additional component in the devp2p node identifier.
-	UserIdent string
+	UserIdent string `toml:",omitempty"`
 
 	// Version should be set to the version number of the program. It is used
 	// in the devp2p node identifier.
-	Version string
+	Version string `toml:"-"`
 
 	// DataDir is the file system folder the node should use for any data storage
 	// requirements. The configured data directory will not be directly shared with
@@ -69,6 +66,9 @@ type Config struct {
 	// in memory.
 	DataDir string
 
+	// Configuration of peer-to-peer networking.
+	P2P p2p.Config
+
 	// KeyStoreDir is the file system folder that contains private keys. The directory can
 	// be specified as a relative path, in which case it is resolved relative to the
 	// current directory.
@@ -76,106 +76,55 @@ type Config struct {
 	// If KeyStoreDir is empty, the default location is the "keystore" subdirectory of
 	// DataDir. If DataDir is unspecified and KeyStoreDir is empty, an ephemeral directory
 	// is created by New and destroyed when the node is stopped.
-	KeyStoreDir string
+	KeyStoreDir string `toml:",omitempty"`
 
 	// UseLightweightKDF lowers the memory and CPU requirements of the key store
 	// scrypt KDF at the expense of security.
-	UseLightweightKDF bool
+	UseLightweightKDF bool `toml:",omitempty"`
 
 	// IPCPath is the requested location to place the IPC endpoint. If the path is
 	// a simple file name, it is placed inside the data directory (or on the root
 	// pipe path on Windows), whereas if it's a resolvable path name (absolute or
 	// relative), then that specific path is enforced. An empty path disables IPC.
-	IPCPath string
-
-	// This field should be a valid secp256k1 private key that will be used for both
-	// remote peer identification as well as network traffic encryption. If no key
-	// is configured, the preset one is loaded from the data dir, generating it if
-	// needed.
-	PrivateKey *ecdsa.PrivateKey
-
-	// NoDiscovery specifies whether the peer discovery mechanism should be started
-	// or not. Disabling is usually useful for protocol debugging (manual topology).
-	NoDiscovery bool
-
-	// DiscoveryV5 specifies whether the the new topic-discovery based V5 discovery
-	// protocol should be started or not.
-	DiscoveryV5 bool
-
-	// Listener address for the V5 discovery protocol UDP traffic.
-	DiscoveryV5Addr string
-
-	// Restrict communication to white listed IP networks.
-	// The whitelist only applies when non-nil.
-	NetRestrict *netutil.Netlist
-
-	// BootstrapNodes used to establish connectivity with the rest of the network.
-	BootstrapNodes []*discover.Node
-
-	// BootstrapNodesV5 used to establish connectivity with the rest of the network
-	// using the V5 discovery protocol.
-	BootstrapNodesV5 []*discv5.Node
-
-	// Network interface address on which the node should listen for inbound peers.
-	ListenAddr string
-
-	// If set to a non-nil value, the given NAT port mapper is used to make the
-	// listening port available to the Internet.
-	NAT nat.Interface
-
-	// If Dialer is set to a non-nil value, the given Dialer is used to dial outbound
-	// peer connections.
-	Dialer *net.Dialer
-
-	// If NoDial is true, the node will not dial any peers.
-	NoDial bool
-
-	// MaxPeers is the maximum number of peers that can be connected. If this is
-	// set to zero, then only the configured static and trusted peers can connect.
-	MaxPeers int
-
-	// MaxPendingPeers is the maximum number of peers that can be pending in the
-	// handshake phase, counted separately for inbound and outbound connections.
-	// Zero defaults to preset values.
-	MaxPendingPeers int
+	IPCPath string `toml:",omitempty"`
 
 	// HTTPHost is the host interface on which to start the HTTP RPC server. If this
 	// field is empty, no HTTP API endpoint will be started.
-	HTTPHost string
+	HTTPHost string `toml:",omitempty"`
 
 	// HTTPPort is the TCP port number on which to start the HTTP RPC server. The
 	// default zero value is/ valid and will pick a port number randomly (useful
 	// for ephemeral nodes).
-	HTTPPort int
+	HTTPPort int `toml:",omitempty"`
 
 	// HTTPCors is the Cross-Origin Resource Sharing header to send to requesting
 	// clients. Please be aware that CORS is a browser enforced security, it's fully
 	// useless for custom HTTP clients.
-	HTTPCors string
+	HTTPCors string `toml:",omitempty"`
 
 	// HTTPModules is a list of API modules to expose via the HTTP RPC interface.
 	// If the module list is empty, all RPC API endpoints designated public will be
 	// exposed.
-	HTTPModules []string
+	HTTPModules []string `toml:",omitempty"`
 
 	// WSHost is the host interface on which to start the websocket RPC server. If
 	// this field is empty, no websocket API endpoint will be started.
-	WSHost string
+	WSHost string `toml:",omitempty"`
 
 	// WSPort is the TCP port number on which to start the websocket RPC server. The
 	// default zero value is/ valid and will pick a port number randomly (useful for
 	// ephemeral nodes).
-	WSPort int
+	WSPort int `toml:",omitempty"`
 
 	// WSOrigins is the list of domain to accept websocket requests from. Please be
 	// aware that the server can only act upon the HTTP request the client sends and
 	// cannot verify the validity of the request header.
-	WSOrigins string
+	WSOrigins string `toml:",omitempty"`
 
 	// WSModules is a list of API modules to expose via the websocket RPC interface.
 	// If the module list is empty, all RPC API endpoints designated public will be
 	// exposed.
-	WSModules []string
+	WSModules []string `toml:",omitempty"`
 }
 
 // IPCEndpoint resolves an IPC endpoint based on a configured value, taking into
@@ -326,8 +275,8 @@ func (c *Config) instanceDir() string {
 // data folder. If no key can be found, a new one is generated.
 func (c *Config) NodeKey() *ecdsa.PrivateKey {
 	// Use any specifically configured key.
-	if c.PrivateKey != nil {
-		return c.PrivateKey
+	if c.P2P.PrivateKey != nil {
+		return c.P2P.PrivateKey
 	}
 	// Generate ephemeral key if no datadir is being used.
 	if c.DataDir == "" {