p2p/discover: implement v5.1 wire protocol (ethereum#21647)

This change implements the Discovery v5.1 wire protocol and
also adds an interactive test suite for this protocol.

cmd/devp2p/README.md

@@ -0,0 +1,86 @@
+# The devp2p command
+
+The devp2p command line tool is a utility for low-level peer-to-peer debugging and
+protocol development purposes. It can do many things.
+
+### ENR Decoding
+
+Use `devp2p enrdump <base64>` to verify and display an Ethereum Node Record.
+
+### Node Key Management
+
+The `devp2p key ...` command family deals with node key files.
+
+Run `devp2p key generate mynode.key` to create a new node key in the `mynode.key` file.
+
+Run `devp2p key to-enode mynode.key -ip 127.0.0.1 -tcp 30303` to create an enode:// URL
+corresponding to the given node key and address information.
+
+### Maintaining DNS Discovery Node Lists
+
+The devp2p command can create and publish DNS discovery node lists.
+
+Run `devp2p dns sign <directory>` to update the signature of a DNS discovery tree.
+
+Run `devp2p dns sync <enrtree-URL>` to download a complete DNS discovery tree.
+
+Run `devp2p dns to-cloudflare <directory>` to publish a tree to CloudFlare DNS.
+
+Run `devp2p dns to-route53 <directory>` to publish a tree to Amazon Route53.
+
+You can find more information about these commands in the [DNS Discovery Setup Guide][dns-tutorial].
+
+### Discovery v4 Utilities
+
+The `devp2p discv4 ...` command family deals with the [Node Discovery v4][discv4]
+protocol.
+
+Run `devp2p discv4 ping <enode/ENR>` to ping a node.
+
+Run `devp2p discv4 resolve <enode/ENR>` to find the most recent node record of a node in
+the DHT.
+
+Run `devp2p discv4 crawl <nodes.json path>` to create or update a JSON node set.
+
+### Discovery v5 Utilities
+
+The `devp2p discv5 ...` command family deals with the [Node Discovery v5][discv5]
+protocol. This protocol is currently under active development.
+
+Run `devp2p discv5 ping <ENR>` to ping a node.
+
+Run `devp2p discv5 resolve <ENR>` to find the most recent node record of a node in
+the discv5 DHT.
+
+Run `devp2p discv5 listen` to run a Discovery v5 node.
+
+Run `devp2p discv5 crawl <nodes.json path>` to create or update a JSON node set containing
+discv5 nodes.
+
+### Discovery Test Suites
+
+The devp2p command also contains interactive test suites for Discovery v4 and Discovery
+v5.
+
+To run these tests against your implementation, you need to set up a networking
+environment where two separate UDP listening addresses are available on the same machine.
+The two listening addresses must also be routed such that they are able to reach the node
+you want to test.
+
+For example, if you want to run the test on your local host, and the node under test is
+also on the local host, you need to assign two IP addresses (or a larger range) to your
+loopback interface. On macOS, this can be done by executing the following command:
+
+    sudo ifconfig lo0 add 127.0.0.2
+
+You can now run either test suite as follows: Start the node under test first, ensuring
+that it won't talk to the Internet (i.e. disable bootstrapping). An easy way to prevent
+unintended connections to the global DHT is listening on `127.0.0.1`.
+
+Now get the ENR of your node and store it in the `NODE` environment variable.
+
+Start the test by running `devp2p discv5 test -listen1 127.0.0.1 -listen2 127.0.0.2 $NODE`.
+
+[dns-tutorial]: https://geth.ethereum.org/docs/developers/dns-discovery-setup
+[discv4]: https://github.com/ethereum/devp2p/tree/master/discv4.md
+[discv5]: https://github.com/ethereum/devp2p/tree/master/discv5/discv5.md

cmd/devp2p/discv4cmd.go

@@ -286,15 +286,23 @@ func listen(ln *enode.LocalNode, addr string) *net.UDPConn {
 	}
 	usocket := socket.(*net.UDPConn)
 	uaddr := socket.LocalAddr().(*net.UDPAddr)
-	ln.SetFallbackIP(net.IP{127, 0, 0, 1})
+	if uaddr.IP.IsUnspecified() {
+		ln.SetFallbackIP(net.IP{127, 0, 0, 1})
+	} else {
+		ln.SetFallbackIP(uaddr.IP)
+	}
 	ln.SetFallbackUDP(uaddr.Port)
 	return usocket
 }
 
 func parseBootnodes(ctx *cli.Context) ([]*enode.Node, error) {
 	s := params.RinkebyBootnodes
 	if ctx.IsSet(bootnodesFlag.Name) {
-		s = strings.Split(ctx.String(bootnodesFlag.Name), ",")
+		input := ctx.String(bootnodesFlag.Name)
+		if input == "" {
+			return nil, nil
+		}
+		s = strings.Split(input, ",")
 	}
 	nodes := make([]*enode.Node, len(s))
 	var err error

cmd/devp2p/discv5cmd.go

@@ -18,9 +18,13 @@ package main
 
 import (
 	"fmt"
+	"os"
 	"time"
 
+	"github.com/ethereum/go-ethereum/cmd/devp2p/internal/v5test"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/internal/utesting"
+	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/p2p/discover"
 	"gopkg.in/urfave/cli.v1"
 )
@@ -33,6 +37,7 @@ var (
 			discv5PingCommand,
 			discv5ResolveCommand,
 			discv5CrawlCommand,
+			discv5TestCommand,
 			discv5ListenCommand,
 		},
 	}
@@ -53,6 +58,12 @@ var (
 		Action: discv5Crawl,
 		Flags:  []cli.Flag{bootnodesFlag, crawlTimeoutFlag},
 	}
+	discv5TestCommand = cli.Command{
+		Name:   "test",
+		Usage:  "Runs protocol tests against a node",
+		Action: discv5Test,
+		Flags:  []cli.Flag{testPatternFlag, testListen1Flag, testListen2Flag},
+	}
 	discv5ListenCommand = cli.Command{
 		Name:   "listen",
 		Usage:  "Runs a node",
@@ -103,6 +114,30 @@ func discv5Crawl(ctx *cli.Context) error {
 	return nil
 }
 
+func discv5Test(ctx *cli.Context) error {
+	// Disable logging unless explicitly enabled.
+	if !ctx.GlobalIsSet("verbosity") && !ctx.GlobalIsSet("vmodule") {
+		log.Root().SetHandler(log.DiscardHandler())
+	}
+
+	// Filter and run test cases.
+	suite := &v5test.Suite{
+		Dest:    getNodeArg(ctx),
+		Listen1: ctx.String(testListen1Flag.Name),
+		Listen2: ctx.String(testListen2Flag.Name),
+	}
+	tests := suite.AllTests()
+	if ctx.IsSet(testPatternFlag.Name) {
+		tests = utesting.MatchTests(tests, ctx.String(testPatternFlag.Name))
+	}
+	results := utesting.RunTests(tests, os.Stdout)
+	if fails := utesting.CountFailures(results); fails > 0 {
+		return fmt.Errorf("%v/%v tests passed.", len(tests)-fails, len(tests))
+	}
+	fmt.Printf("%v/%v passed\n", len(tests), len(tests))
+	return nil
+}
+
 func discv5Listen(ctx *cli.Context) error {
 	disc := startV5(ctx)
 	defer disc.Close()