p2p/discover: add initial discovery v5 implementation (#20750)

This adds an implementation of the current discovery v5 spec.

There is full integration with cmd/devp2p and enode.Iterator in this
version. In theory we could enable the new protocol as a replacement of
discovery v4 at any time. In practice, there will likely be a few more
changes to the spec and implementation before this can happen.

cmd/devp2p/discv5cmd.go

@@ -0,0 +1,123 @@
+// 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"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/p2p/discover"
+	"gopkg.in/urfave/cli.v1"
+)
+
+var (
+	discv5Command = cli.Command{
+		Name:  "discv5",
+		Usage: "Node Discovery v5 tools",
+		Subcommands: []cli.Command{
+			discv5PingCommand,
+			discv5ResolveCommand,
+			discv5CrawlCommand,
+			discv5ListenCommand,
+		},
+	}
+	discv5PingCommand = cli.Command{
+		Name:   "ping",
+		Usage:  "Sends ping to a node",
+		Action: discv5Ping,
+	}
+	discv5ResolveCommand = cli.Command{
+		Name:   "resolve",
+		Usage:  "Finds a node in the DHT",
+		Action: discv5Resolve,
+		Flags:  []cli.Flag{bootnodesFlag},
+	}
+	discv5CrawlCommand = cli.Command{
+		Name:   "crawl",
+		Usage:  "Updates a nodes.json file with random nodes found in the DHT",
+		Action: discv5Crawl,
+		Flags:  []cli.Flag{bootnodesFlag, crawlTimeoutFlag},
+	}
+	discv5ListenCommand = cli.Command{
+		Name:   "listen",
+		Usage:  "Runs a node",
+		Action: discv5Listen,
+		Flags: []cli.Flag{
+			bootnodesFlag,
+			nodekeyFlag,
+			nodedbFlag,
+			listenAddrFlag,
+		},
+	}
+)
+
+func discv5Ping(ctx *cli.Context) error {
+	n := getNodeArg(ctx)
+	disc := startV5(ctx)
+	defer disc.Close()
+
+	fmt.Println(disc.Ping(n))
+	return nil
+}
+
+func discv5Resolve(ctx *cli.Context) error {
+	n := getNodeArg(ctx)
+	disc := startV5(ctx)
+	defer disc.Close()
+
+	fmt.Println(disc.Resolve(n))
+	return nil
+}
+
+func discv5Crawl(ctx *cli.Context) error {
+	if ctx.NArg() < 1 {
+		return fmt.Errorf("need nodes file as argument")
+	}
+	nodesFile := ctx.Args().First()
+	var inputSet nodeSet
+	if common.FileExist(nodesFile) {
+		inputSet = loadNodesJSON(nodesFile)
+	}
+
+	disc := startV5(ctx)
+	defer disc.Close()
+	c := newCrawler(inputSet, disc, disc.RandomNodes())
+	c.revalidateInterval = 10 * time.Minute
+	output := c.run(ctx.Duration(crawlTimeoutFlag.Name))
+	writeNodesJSON(nodesFile, output)
+	return nil
+}
+
+func discv5Listen(ctx *cli.Context) error {
+	disc := startV5(ctx)
+	defer disc.Close()
+
+	fmt.Println(disc.Self())
+	select {}
+}
+
+// startV5 starts an ephemeral discovery v5 node.
+func startV5(ctx *cli.Context) *discover.UDPv5 {
+	ln, config := makeDiscoveryConfig(ctx)
+	socket := listen(ln, ctx.String(listenAddrFlag.Name))
+	disc, err := discover.ListenV5(socket, ln, config)
+	if err != nil {
+		exit(err)
+	}
+	return disc
+}