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// Copyright 2019 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
package main
import (
"fmt"
"net"
"sort"
"strings"
"time"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/p2p/discover"
"github.com/ethereum/go-ethereum/p2p/enode"
"github.com/ethereum/go-ethereum/params"
"gopkg.in/urfave/cli.v1"
)
var (
discv4Command = cli.Command{
Name: "discv4",
Usage: "Node Discovery v4 tools",
Subcommands: []cli.Command{
discv4PingCommand,
discv4RequestRecordCommand,
discv4ResolveCommand,
},
}
discv4PingCommand = cli.Command{
Name: "ping",
Usage: "Sends ping to a node",
Action: discv4Ping,
}
discv4RequestRecordCommand = cli.Command{
Name: "requestenr",
Usage: "Requests a node record using EIP-868 enrRequest",
Action: discv4RequestRecord,
}
discv4ResolveCommand = cli.Command{
Name: "resolve",
Usage: "Finds a node in the DHT",
Action: discv4Resolve,
Flags: []cli.Flag{bootnodesFlag},
}
)
var bootnodesFlag = cli.StringFlag{
Name: "bootnodes",
Usage: "Comma separated nodes used for bootstrapping",
}
func discv4Ping(ctx *cli.Context) error {
n, disc, err := getNodeArgAndStartV4(ctx)
if err != nil {
return err
}
defer disc.Close()
start := time.Now()
if err := disc.Ping(n); err != nil {
return fmt.Errorf("node didn't respond: %v", err)
}
fmt.Printf("node responded to ping (RTT %v).\n", time.Since(start))
return nil
}
func discv4RequestRecord(ctx *cli.Context) error {
n, disc, err := getNodeArgAndStartV4(ctx)
if err != nil {
return err
}
defer disc.Close()
respN, err := disc.RequestENR(n)
if err != nil {
return fmt.Errorf("can't retrieve record: %v", err)
}
fmt.Println(respN.String())
return nil
}
func discv4Resolve(ctx *cli.Context) error {
n, disc, err := getNodeArgAndStartV4(ctx)
if err != nil {
return err
}
defer disc.Close()
fmt.Println(disc.Resolve(n).String())
return nil
}
func getNodeArgAndStartV4(ctx *cli.Context) (*enode.Node, *discover.UDPv4, error) {
if ctx.NArg() != 1 {
return nil, nil, fmt.Errorf("missing node as command-line argument")
}
n, err := parseNode(ctx.Args()[0])
if err != nil {
return nil, nil, err
}
var bootnodes []*enode.Node
if commandHasFlag(ctx, bootnodesFlag) {
bootnodes, err = parseBootnodes(ctx)
if err != nil {
return nil, nil, err
}
}
disc, err := startV4(bootnodes)
return n, disc, err
}
func parseBootnodes(ctx *cli.Context) ([]*enode.Node, error) {
s := params.RinkebyBootnodes
if ctx.IsSet(bootnodesFlag.Name) {
s = strings.Split(ctx.String(bootnodesFlag.Name), ",")
}
nodes := make([]*enode.Node, len(s))
var err error
for i, record := range s {
nodes[i], err = parseNode(record)
if err != nil {
return nil, fmt.Errorf("invalid bootstrap node: %v", err)
}
}
return nodes, nil
}
// commandHasFlag returns true if the current command supports the given flag.
func commandHasFlag(ctx *cli.Context, flag cli.Flag) bool {
flags := ctx.FlagNames()
sort.Strings(flags)
i := sort.SearchStrings(flags, flag.GetName())
return i != len(flags) && flags[i] == flag.GetName()
}
// startV4 starts an ephemeral discovery V4 node.
func startV4(bootnodes []*enode.Node) (*discover.UDPv4, error) {
var cfg discover.Config
cfg.Bootnodes = bootnodes
cfg.PrivateKey, _ = crypto.GenerateKey()
db, _ := enode.OpenDB("")
ln := enode.NewLocalNode(db, cfg.PrivateKey)
socket, err := net.ListenUDP("udp4", &net.UDPAddr{IP: net.IP{0, 0, 0, 0}})
if err != nil {
return nil, err
}
addr := socket.LocalAddr().(*net.UDPAddr)
ln.SetFallbackIP(net.IP{127, 0, 0, 1})
ln.SetFallbackUDP(addr.Port)
return discover.ListenUDP(socket, ln, cfg)
}
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