Merge 9b5737150a into dddbaa4bf3

cmd/devp2p/README.md

@@ -80,6 +80,13 @@ 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.
 
+### Combined Discovery
+
+Run `devp2p discovery listen` to run a node speaking all supported discovery protocol
+versions (currently discv4 and discv5) on a single UDP port. For a single-protocol node, use
+`devp2p discv4 listen` or `devp2p discv5 listen`. Add `--rpc <addr>` to expose the
+per-protocol HTTP API (`discv4_*`, `discv5_*`).
+
 ### Discovery Test Suites
 
 The devp2p command also contains interactive test suites for Discovery v4 and Discovery

cmd/devp2p/discoverycmd.go

@@ -0,0 +1,76 @@
+// Copyright 2026 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"
+	"slices"
+
+	"github.com/ethereum/go-ethereum/p2p/discover"
+	"github.com/urfave/cli/v2"
+)
+
+var (
+	discoveryCommand = &cli.Command{
+		Name:  "discovery",
+		Usage: "Node Discovery tools",
+		Subcommands: []*cli.Command{
+			discoveryListenCommand,
+		},
+	}
+	discoveryListenCommand = &cli.Command{
+		Name:   "listen",
+		Usage:  "Runs a discovery node speaking all supported protocol versions on one UDP port",
+		Action: discoveryListen,
+		Flags: slices.Concat(discoveryNodeFlags, []cli.Flag{
+			httpAddrFlag,
+		}),
+	}
+)
+
+func discoveryListen(ctx *cli.Context) error {
+	ln, config := makeDiscoveryConfig(ctx)
+	socket := listen(ctx, ln)
+
+	// v4 is the primary listener on the real socket and forwards packets it
+	// can't parse to v5 via the unhandled channel.
+	unhandled := make(chan discover.ReadPacket, 100)
+	v4cfg := config
+	v4cfg.Unhandled = unhandled
+	v4, err := discover.ListenV4(socket, ln, v4cfg)
+	if err != nil {
+		exit(err)
+	}
+	v5, err := discover.ListenV5(&discover.SharedUDPConn{UDPConn: socket, Unhandled: unhandled}, ln, config)
+	if err != nil {
+		exit(err)
+	}
+	// Close v4 before v5: when sharing the socket, v5's read loop only unblocks
+	// once v4 closes the underlying socket and the unhandled channel.
+	defer func() {
+		v4.Close()
+		v5.Close()
+	}()
+
+	// v4 and v5 share the same local node, so this is the single record both announce.
+	fmt.Println(ln.Node())
+
+	return runRPCServer(ctx.String(httpAddrFlag.Name), map[string]any{
+		"discv4": &discv4API{v4},
+		"discv5": &discv5API{v5},
+	})
+}

cmd/devp2p/discv4cmd.go

@@ -17,10 +17,10 @@
 package main
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"net"
-	"net/http"
 	"slices"
 	"strconv"
 	"strings"
@@ -29,11 +29,9 @@ import (
 	"github.com/ethereum/go-ethereum/cmd/devp2p/internal/v4test"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
-	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/p2p/discover"
 	"github.com/ethereum/go-ethereum/p2p/enode"
 	"github.com/ethereum/go-ethereum/params"
-	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/urfave/cli/v2"
 )
 
@@ -176,19 +174,7 @@ func discv4Listen(ctx *cli.Context) error {
 
 	fmt.Println(disc.Self())
 
-	httpAddr := ctx.String(httpAddrFlag.Name)
+	return runRPCServer(ctx.String(httpAddrFlag.Name), map[string]any{"discv4": &discv4API{disc}})
-	if httpAddr == "" {
-		// Non-HTTP mode.
-		select {}
-	}
-
-	api := &discv4API{disc}
-	log.Info("Starting RPC API server", "addr", httpAddr)
-	srv := rpc.NewServer()
-	srv.RegisterName("discv4", api)
-	http.DefaultServeMux.Handle("/", srv)
-	httpsrv := http.Server{Addr: httpAddr, Handler: http.DefaultServeMux}
-	return httpsrv.ListenAndServe()
 }
 
 func discv4RequestRecord(ctx *cli.Context) error {
@@ -428,13 +414,14 @@ type discv4API struct {
 	host *discover.UDPv4
 }
 
-func (api *discv4API) LookupRandom(n int) (ns []*enode.Node) {
+func (api *discv4API) LookupRandom(ctx context.Context, n int) []*enode.Node {
 	it := api.host.RandomNodes()
 	defer it.Close()
-	for len(ns) < n && it.Next() {
+	go func() {
-		ns = append(ns, it.Node())
+		<-ctx.Done()
-	}
+		it.Close()
-	return ns
+	}()
+	return enode.ReadNodes(it, n)
 }
 
 func (api *discv4API) Buckets() [][]discover.BucketNode {

cmd/devp2p/discv5cmd.go

@@ -17,6 +17,7 @@
 package main
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"slices"
@@ -25,6 +26,7 @@ import (
 	"github.com/ethereum/go-ethereum/cmd/devp2p/internal/v5test"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/p2p/discover"
+	"github.com/ethereum/go-ethereum/p2p/enode"
 	"github.com/urfave/cli/v2"
 )
 
@@ -76,7 +78,9 @@ var (
 		Name:   "listen",
 		Usage:  "Runs a node",
 		Action: discv5Listen,
-		Flags:  discoveryNodeFlags,
+		Flags: slices.Concat(discoveryNodeFlags, []cli.Flag{
+			httpAddrFlag,
+		}),
 	}
 )
 
@@ -137,7 +141,8 @@ func discv5Listen(ctx *cli.Context) error {
 	defer disc.Close()
 
 	fmt.Println(disc.Self())
-	select {}
+
+	return runRPCServer(ctx.String(httpAddrFlag.Name), map[string]any{"discv5": &discv5API{disc}})
 }
 
 // startV5 starts an ephemeral discovery v5 node.
@@ -150,3 +155,21 @@ func startV5(ctx *cli.Context) (*discover.UDPv5, discover.Config) {
 	}
 	return disc, config
 }
+
+type discv5API struct {
+	host *discover.UDPv5
+}
+
+func (api *discv5API) LookupRandom(ctx context.Context, n int) []*enode.Node {
+	it := api.host.RandomNodes()
+	defer it.Close()
+	go func() {
+		<-ctx.Done()
+		it.Close()
+	}()
+	return enode.ReadNodes(it, n)
+}
+
+func (api *discv5API) Self() *enode.Node {
+	return api.host.Self()
+}

cmd/devp2p/main.go

@@ -18,11 +18,14 @@ package main
 
 import (
 	"fmt"
+	"net/http"
 	"os"
 
 	"github.com/ethereum/go-ethereum/internal/debug"
 	"github.com/ethereum/go-ethereum/internal/flags"
+	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/p2p/enode"
+	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/urfave/cli/v2"
 )
 
@@ -49,6 +52,7 @@ func init() {
 		keyCommand,
 		discv4Command,
 		discv5Command,
+		discoveryCommand,
 		dnsCommand,
 		nodesetCommand,
 		rlpxCommand,
@@ -92,6 +96,22 @@ func getNodeArg(ctx *cli.Context) *enode.Node {
 	return n
 }
 
+// runRPCServer serves the given RPC APIs on httpAddr; if httpAddr is empty, it blocks forever without serving.
+func runRPCServer(httpAddr string, apis map[string]any) error {
+	if httpAddr == "" {
+		select {}
+	}
+	srv := rpc.NewServer()
+	for name, api := range apis {
+		if err := srv.RegisterName(name, api); err != nil {
+			return err
+		}
+	}
+	log.Info("Starting RPC API server", "addr", httpAddr)
+	httpsrv := http.Server{Addr: httpAddr, Handler: srv}
+	return httpsrv.ListenAndServe()
+}
+
 func exit(err interface{}) {
 	if err == nil {
 		os.Exit(0)

p2p/discover/common.go

@@ -21,6 +21,7 @@ import (
 	"crypto/ecdsa"
 	crand "crypto/rand"
 	"encoding/binary"
+	"errors"
 	"iter"
 	"math/rand"
 	"net"
@@ -105,6 +106,30 @@ type ReadPacket struct {
 	Addr netip.AddrPort
 }
 
+// SharedUDPConn implements a shared connection. Write sends messages to the underlying
+// connection while read returns messages that were found unprocessable and sent to the
+// Unhandled channel by the primary listener.
+type SharedUDPConn struct {
+	*net.UDPConn
+	Unhandled chan ReadPacket
+}
+
+// ReadFromUDPAddrPort implements UDPConn.
+func (s *SharedUDPConn) ReadFromUDPAddrPort(b []byte) (n int, addr netip.AddrPort, err error) {
+	packet, ok := <-s.Unhandled
+	if !ok {
+		return 0, netip.AddrPort{}, errors.New("connection was closed")
+	}
+	l := min(len(packet.Data), len(b))
+	copy(b[:l], packet.Data[:l])
+	return l, packet.Addr, nil
+}
+
+// Close implements UDPConn. It does not close the underlying connection.
+func (s *SharedUDPConn) Close() error {
+	return nil
+}
+
 type randomSource interface {
 	Intn(int) int
 	Int63n(int64) int64

p2p/server.go

@@ -330,32 +330,6 @@ func (srv *Server) Stop() {
 	srv.loopWG.Wait()
 }
 
-// sharedUDPConn implements a shared connection. Write sends messages to the underlying connection while read returns
-// messages that were found unprocessable and sent to the unhandled channel by the primary listener.
-type sharedUDPConn struct {
-	*net.UDPConn
-	unhandled chan discover.ReadPacket
-}
-
-// ReadFromUDPAddrPort implements discover.UDPConn
-func (s *sharedUDPConn) ReadFromUDPAddrPort(b []byte) (n int, addr netip.AddrPort, err error) {
-	packet, ok := <-s.unhandled
-	if !ok {
-		return 0, netip.AddrPort{}, errors.New("connection was closed")
-	}
-	l := len(packet.Data)
-	if l > len(b) {
-		l = len(b)
-	}
-	copy(b[:l], packet.Data[:l])
-	return l, packet.Addr, nil
-}
-
-// Close implements discover.UDPConn
-func (s *sharedUDPConn) Close() error {
-	return nil
-}
-
 // Start starts running the server.
 // Servers can not be re-used after stopping.
 func (srv *Server) Start() (err error) {
@@ -463,7 +437,7 @@ func (srv *Server) setupDiscovery() error {
 	// connection, so v5 can read unhandled messages from v4.
 	if srv.Config.DiscoveryV4 && srv.Config.DiscoveryV5 {
 		unhandled = make(chan discover.ReadPacket, 100)
-		sconn = &sharedUDPConn{conn, unhandled}
+		sconn = &discover.SharedUDPConn{UDPConn: conn, Unhandled: unhandled}
 	}
 
 	// Start discovery services.