p2p, p2p/discover, p2p/discv5: implement UDP port sharing (ethereum#1…

…5200) This commit affects p2p/discv5 "topic discovery" by running it on the same UDP port where the old discovery works. This is realized by giving an "unhandled" packet channel to the old v4 discovery packet handler where all invalid packets are sent. These packets are then processed by v5. v5 packets are always invalid when interpreted by v4 and vice versa. This is ensured by adding one to the first byte of the packet hash in v5 packets. DiscoveryV5Bootnodes is also changed to point to new bootnodes that are implementing the changed packet format with modified hash. Existing and new v5 bootnodes are both running on different ports ATM.
KennyWZhang · Jan 22, 2018 · 92580d6 · 92580d6
1 parent 02aeb3d
commit 92580d6
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Showing 17 changed files with 150 additions and 91 deletions.
diff --git a/cmd/bootnode/main.go b/cmd/bootnode/main.go
@@ -21,6 +21,7 @@ import (
 	"crypto/ecdsa"
 	"flag"
 	"fmt"
+	"net"
 	"os"
 
 	"github.com/ethereum/go-ethereum/cmd/utils"
@@ -96,12 +97,32 @@ func main() {
 		}
 	}
 
+	addr, err := net.ResolveUDPAddr("udp", *listenAddr)
+	if err != nil {
+		utils.Fatalf("-ResolveUDPAddr: %v", err)
+	}
+	conn, err := net.ListenUDP("udp", addr)
+	if err != nil {
+		utils.Fatalf("-ListenUDP: %v", err)
+	}
+
+	realaddr := conn.LocalAddr().(*net.UDPAddr)
+	if natm != nil {
+		if !realaddr.IP.IsLoopback() {
+			go nat.Map(natm, nil, "udp", realaddr.Port, realaddr.Port, "ethereum discovery")
+		}
+		// TODO: react to external IP changes over time.
+		if ext, err := natm.ExternalIP(); err == nil {
+			realaddr = &net.UDPAddr{IP: ext, Port: realaddr.Port}
+		}
+	}
+
 	if *runv5 {
-		if _, err := discv5.ListenUDP(nodeKey, *listenAddr, natm, "", restrictList); err != nil {
+		if _, err := discv5.ListenUDP(nodeKey, conn, realaddr, "", restrictList); err != nil {
 			utils.Fatalf("%v", err)
 		}
 	} else {
-		if _, err := discover.ListenUDP(nodeKey, *listenAddr, natm, "", restrictList); err != nil {
+		if _, err := discover.ListenUDP(nodeKey, conn, realaddr, nil, "", restrictList); err != nil {
 			utils.Fatalf("%v", err)
 		}
 	}

diff --git a/cmd/faucet/faucet.go b/cmd/faucet/faucet.go
@@ -223,7 +223,6 @@ func newFaucet(genesis *core.Genesis, port int, enodes []*discv5.Node, network u
 			NoDiscovery:      true,
 			DiscoveryV5:      true,
 			ListenAddr:       fmt.Sprintf(":%d", port),
-			DiscoveryV5Addr:  fmt.Sprintf(":%d", port+1),
 			MaxPeers:         25,
 			BootstrapNodesV5: enodes,
 		},

diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
@@ -636,14 +636,6 @@ func setListenAddress(ctx *cli.Context, cfg *p2p.Config) {
 	}
 }
 
-// setDiscoveryV5Address creates a UDP listening address string from set command
-// line flags for the V5 discovery protocol.
-func setDiscoveryV5Address(ctx *cli.Context, cfg *p2p.Config) {
-	if ctx.GlobalIsSet(ListenPortFlag.Name) {
-		cfg.DiscoveryV5Addr = fmt.Sprintf(":%d", ctx.GlobalInt(ListenPortFlag.Name)+1)
-	}
-}
-
 // setNAT creates a port mapper from command line flags.
 func setNAT(ctx *cli.Context, cfg *p2p.Config) {
 	if ctx.GlobalIsSet(NATFlag.Name) {
@@ -794,7 +786,6 @@ func SetP2PConfig(ctx *cli.Context, cfg *p2p.Config) {
 	setNodeKey(ctx, cfg)
 	setNAT(ctx, cfg)
 	setListenAddress(ctx, cfg)
-	setDiscoveryV5Address(ctx, cfg)
 	setBootstrapNodes(ctx, cfg)
 	setBootstrapNodesV5(ctx, cfg)
 
@@ -830,7 +821,6 @@ func SetP2PConfig(ctx *cli.Context, cfg *p2p.Config) {
 		// --dev mode can't use p2p networking.
 		cfg.MaxPeers = 0
 		cfg.ListenAddr = ":0"
-		cfg.DiscoveryV5Addr = ":0"
 		cfg.NoDiscovery = true
 		cfg.DiscoveryV5 = false
 	}

diff --git a/les/backend.go b/les/backend.go
@@ -221,9 +221,8 @@ func (s *LightEthereum) Start(srvr *p2p.Server) error {
 	s.startBloomHandlers()
 	log.Warn("Light client mode is an experimental feature")
 	s.netRPCService = ethapi.NewPublicNetAPI(srvr, s.networkId)
-	// search the topic belonging to the oldest supported protocol because
-	// servers always advertise all supported protocols
-	protocolVersion := ClientProtocolVersions[len(ClientProtocolVersions)-1]
+	// clients are searching for the first advertised protocol in the list
+	protocolVersion := AdvertiseProtocolVersions[0]
 	s.serverPool.start(srvr, lesTopic(s.blockchain.Genesis().Hash(), protocolVersion))
 	s.protocolManager.Start()
 	return nil

diff --git a/les/protocol.go b/les/protocol.go
@@ -41,8 +41,9 @@ const (
 
 // Supported versions of the les protocol (first is primary)
 var (
-	ClientProtocolVersions = []uint{lpv2, lpv1}
-	ServerProtocolVersions = []uint{lpv2, lpv1}
+	ClientProtocolVersions    = []uint{lpv2, lpv1}
+	ServerProtocolVersions    = []uint{lpv2, lpv1}
+	AdvertiseProtocolVersions = []uint{lpv2} // clients are searching for the first advertised protocol in the list
 )
 
 // Number of implemented message corresponding to different protocol versions.

diff --git a/les/server.go b/les/server.go
@@ -56,8 +56,8 @@ func NewLesServer(eth *eth.Ethereum, config *eth.Config) (*LesServer, error) {
 		return nil, err
 	}
 
-	lesTopics := make([]discv5.Topic, len(ServerProtocolVersions))
-	for i, pv := range ServerProtocolVersions {
+	lesTopics := make([]discv5.Topic, len(AdvertiseProtocolVersions))
+	for i, pv := range AdvertiseProtocolVersions {
 		lesTopics[i] = lesTopic(eth.BlockChain().Genesis().Hash(), pv)
 	}
 

diff --git a/mobile/geth.go b/mobile/geth.go
@@ -116,7 +116,6 @@ func NewNode(datadir string, config *NodeConfig) (stack *Node, _ error) {
 		P2P: p2p.Config{
 			NoDiscovery:      true,
 			DiscoveryV5:      true,
-			DiscoveryV5Addr:  ":0",
 			BootstrapNodesV5: config.BootstrapNodes.nodes,
 			ListenAddr:       ":0",
 			NAT:              nat.Any(),

diff --git a/node/defaults.go b/node/defaults.go
@@ -41,10 +41,9 @@ var DefaultConfig = Config{
 	WSPort:      DefaultWSPort,
 	WSModules:   []string{"net", "web3"},
 	P2P: p2p.Config{
-		ListenAddr:      ":30303",
-		DiscoveryV5Addr: ":30304",
-		MaxPeers:        25,
-		NAT:             nat.Any(),
+		ListenAddr: ":30303",
+		MaxPeers:   25,
+		NAT:        nat.Any(),
 	},
 }
 

diff --git a/p2p/discover/udp.go b/p2p/discover/udp.go
@@ -210,25 +210,23 @@ type reply struct {
 	matched chan<- bool
 }
 
+// ReadPacket is sent to the unhandled channel when it could not be processed
+type ReadPacket struct {
+	Data []byte
+	Addr *net.UDPAddr
+}
+
 // ListenUDP returns a new table that listens for UDP packets on laddr.
-func ListenUDP(priv *ecdsa.PrivateKey, laddr string, natm nat.Interface, nodeDBPath string, netrestrict *netutil.Netlist) (*Table, error) {
-	addr, err := net.ResolveUDPAddr("udp", laddr)
-	if err != nil {
-		return nil, err
-	}
-	conn, err := net.ListenUDP("udp", addr)
-	if err != nil {
-		return nil, err
-	}
-	tab, _, err := newUDP(priv, conn, natm, nodeDBPath, netrestrict)
+func ListenUDP(priv *ecdsa.PrivateKey, conn conn, realaddr *net.UDPAddr, unhandled chan ReadPacket, nodeDBPath string, netrestrict *netutil.Netlist) (*Table, error) {
+	tab, _, err := newUDP(priv, conn, realaddr, unhandled, nodeDBPath, netrestrict)
 	if err != nil {
 		return nil, err
 	}
 	log.Info("UDP listener up", "self", tab.self)
 	return tab, nil
 }
 
-func newUDP(priv *ecdsa.PrivateKey, c conn, natm nat.Interface, nodeDBPath string, netrestrict *netutil.Netlist) (*Table, *udp, error) {
+func newUDP(priv *ecdsa.PrivateKey, c conn, realaddr *net.UDPAddr, unhandled chan ReadPacket, nodeDBPath string, netrestrict *netutil.Netlist) (*Table, *udp, error) {
 	udp := &udp{
 		conn:        c,
 		priv:        priv,
@@ -237,16 +235,6 @@ func newUDP(priv *ecdsa.PrivateKey, c conn, natm nat.Interface, nodeDBPath strin
 		gotreply:    make(chan reply),
 		addpending:  make(chan *pending),
 	}
-	realaddr := c.LocalAddr().(*net.UDPAddr)
-	if natm != nil {
-		if !realaddr.IP.IsLoopback() {
-			go nat.Map(natm, udp.closing, "udp", realaddr.Port, realaddr.Port, "ethereum discovery")
-		}
-		// TODO: react to external IP changes over time.
-		if ext, err := natm.ExternalIP(); err == nil {
-			realaddr = &net.UDPAddr{IP: ext, Port: realaddr.Port}
-		}
-	}
 	// TODO: separate TCP port
 	udp.ourEndpoint = makeEndpoint(realaddr, uint16(realaddr.Port))
 	tab, err := newTable(udp, PubkeyID(&priv.PublicKey), realaddr, nodeDBPath)
@@ -256,7 +244,7 @@ func newUDP(priv *ecdsa.PrivateKey, c conn, natm nat.Interface, nodeDBPath strin
 	udp.Table = tab
 
 	go udp.loop()
-	go udp.readLoop()
+	go udp.readLoop(unhandled)
 	return udp.Table, udp, nil
 }
 
@@ -492,8 +480,11 @@ func encodePacket(priv *ecdsa.PrivateKey, ptype byte, req interface{}) ([]byte,
 }
 
 // readLoop runs in its own goroutine. it handles incoming UDP packets.
-func (t *udp) readLoop() {
+func (t *udp) readLoop(unhandled chan ReadPacket) {
 	defer t.conn.Close()
+	if unhandled != nil {
+		defer close(unhandled)
+	}
 	// Discovery packets are defined to be no larger than 1280 bytes.
 	// Packets larger than this size will be cut at the end and treated
 	// as invalid because their hash won't match.
@@ -509,7 +500,12 @@ func (t *udp) readLoop() {
 			log.Debug("UDP read error", "err", err)
 			return
 		}
-		t.handlePacket(from, buf[:nbytes])
+		if t.handlePacket(from, buf[:nbytes]) != nil && unhandled != nil {
+			select {
+			case unhandled <- ReadPacket{buf[:nbytes], from}:
+			default:
+			}
+		}
 	}
 }
 

diff --git a/p2p/discover/udp_test.go b/p2p/discover/udp_test.go
@@ -70,7 +70,8 @@ func newUDPTest(t *testing.T) *udpTest {
 		remotekey:  newkey(),
 		remoteaddr: &net.UDPAddr{IP: net.IP{10, 0, 1, 99}, Port: 30303},
 	}
-	test.table, test.udp, _ = newUDP(test.localkey, test.pipe, nil, "", nil)
+	realaddr := test.pipe.LocalAddr().(*net.UDPAddr)
+	test.table, test.udp, _ = newUDP(test.localkey, test.pipe, realaddr, nil, "", nil)
 	return test
 }
 

diff --git a/p2p/discv5/net.go b/p2p/discv5/net.go
@@ -29,7 +29,6 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/crypto/sha3"
 	"github.com/ethereum/go-ethereum/log"
-	"github.com/ethereum/go-ethereum/p2p/nat"
 	"github.com/ethereum/go-ethereum/p2p/netutil"
 	"github.com/ethereum/go-ethereum/rlp"
 )
@@ -134,7 +133,7 @@ type timeoutEvent struct {
 	node *Node
 }
 
-func newNetwork(conn transport, ourPubkey ecdsa.PublicKey, natm nat.Interface, dbPath string, netrestrict *netutil.Netlist) (*Network, error) {
+func newNetwork(conn transport, ourPubkey ecdsa.PublicKey, dbPath string, netrestrict *netutil.Netlist) (*Network, error) {
 	ourID := PubkeyID(&ourPubkey)
 
 	var db *nodeDB

diff --git a/p2p/discv5/net_test.go b/p2p/discv5/net_test.go
@@ -28,7 +28,7 @@ import (
 
 func TestNetwork_Lookup(t *testing.T) {
 	key, _ := crypto.GenerateKey()
-	network, err := newNetwork(lookupTestnet, key.PublicKey, nil, "", nil)
+	network, err := newNetwork(lookupTestnet, key.PublicKey, "", nil)
 	if err != nil {
 		t.Fatal(err)
 	}

diff --git a/p2p/discv5/sim_test.go b/p2p/discv5/sim_test.go
@@ -282,7 +282,7 @@ func (s *simulation) launchNode(log bool) *Network {
 	addr := &net.UDPAddr{IP: ip, Port: 30303}
 
 	transport := &simTransport{joinTime: time.Now(), sender: id, senderAddr: addr, sim: s, priv: key}
-	net, err := newNetwork(transport, key.PublicKey, nil, "<no database>", nil)
+	net, err := newNetwork(transport, key.PublicKey, "<no database>", nil)
 	if err != nil {
 		panic("cannot launch new node: " + err.Error())
 	}

diff --git a/p2p/discv5/ticket.go b/p2p/discv5/ticket.go
@@ -642,7 +642,7 @@ func (s *ticketStore) gotTopicNodes(from *Node, hash common.Hash, nodes []rpcNod
 		if ip.IsUnspecified() || ip.IsLoopback() {
 			ip = from.IP
 		}
-		n := NewNode(node.ID, ip, node.UDP-1, node.TCP-1) // subtract one from port while discv5 is running in test mode on UDPport+1
+		n := NewNode(node.ID, ip, node.UDP, node.TCP)
 		select {
 		case chn <- n:
 		default:

diff --git a/p2p/discv5/udp.go b/p2p/discv5/udp.go
@@ -37,7 +37,7 @@ const Version = 4
 // Errors
 var (
 	errPacketTooSmall   = errors.New("too small")
-	errBadHash          = errors.New("bad hash")
+	errBadPrefix        = errors.New("bad prefix")
 	errExpired          = errors.New("expired")
 	errUnsolicitedReply = errors.New("unsolicited reply")
 	errUnknownNode      = errors.New("unknown node")
@@ -145,10 +145,11 @@ type (
 	}
 )
 
-const (
-	macSize  = 256 / 8
-	sigSize  = 520 / 8
-	headSize = macSize + sigSize // space of packet frame data
+var (
+	versionPrefix     = []byte("temporary discovery v5")
+	versionPrefixSize = len(versionPrefix)
+	sigSize           = 520 / 8
+	headSize          = versionPrefixSize + sigSize // space of packet frame data
 )
 
 // Neighbors replies are sent across multiple packets to
@@ -237,12 +238,12 @@ type udp struct {
 }
 
 // ListenUDP returns a new table that listens for UDP packets on laddr.
-func ListenUDP(priv *ecdsa.PrivateKey, laddr string, natm nat.Interface, nodeDBPath string, netrestrict *netutil.Netlist) (*Network, error) {
-	transport, err := listenUDP(priv, laddr)
+func ListenUDP(priv *ecdsa.PrivateKey, conn conn, realaddr *net.UDPAddr, nodeDBPath string, netrestrict *netutil.Netlist) (*Network, error) {
+	transport, err := listenUDP(priv, conn, realaddr)
 	if err != nil {
 		return nil, err
 	}
-	net, err := newNetwork(transport, priv.PublicKey, natm, nodeDBPath, netrestrict)
+	net, err := newNetwork(transport, priv.PublicKey, nodeDBPath, netrestrict)
 	if err != nil {
 		return nil, err
 	}
@@ -251,16 +252,8 @@ func ListenUDP(priv *ecdsa.PrivateKey, laddr string, natm nat.Interface, nodeDBP
 	return net, nil
 }
 
-func listenUDP(priv *ecdsa.PrivateKey, laddr string) (*udp, error) {
-	addr, err := net.ResolveUDPAddr("udp", laddr)
-	if err != nil {
-		return nil, err
-	}
-	conn, err := net.ListenUDP("udp", addr)
-	if err != nil {
-		return nil, err
-	}
-	return &udp{conn: conn, priv: priv, ourEndpoint: makeEndpoint(addr, uint16(addr.Port))}, nil
+func listenUDP(priv *ecdsa.PrivateKey, conn conn, realaddr *net.UDPAddr) (*udp, error) {
+	return &udp{conn: conn, priv: priv, ourEndpoint: makeEndpoint(realaddr, uint16(realaddr.Port))}, nil
 }
 
 func (t *udp) localAddr() *net.UDPAddr {
@@ -372,11 +365,9 @@ func encodePacket(priv *ecdsa.PrivateKey, ptype byte, req interface{}) (p, hash
 		log.Error(fmt.Sprint("could not sign packet:", err))
 		return nil, nil, err
 	}
-	copy(packet[macSize:], sig)
-	// add the hash to the front. Note: this doesn't protect the
-	// packet in any way.
-	hash = crypto.Keccak256(packet[macSize:])
-	copy(packet, hash)
+	copy(packet, versionPrefix)
+	copy(packet[versionPrefixSize:], sig)
+	hash = crypto.Keccak256(packet[versionPrefixSize:])
 	return packet, hash, nil
 }
 
@@ -420,17 +411,16 @@ func decodePacket(buffer []byte, pkt *ingressPacket) error {
 	}
 	buf := make([]byte, len(buffer))
 	copy(buf, buffer)
-	hash, sig, sigdata := buf[:macSize], buf[macSize:headSize], buf[headSize:]
-	shouldhash := crypto.Keccak256(buf[macSize:])
-	if !bytes.Equal(hash, shouldhash) {
-		return errBadHash
+	prefix, sig, sigdata := buf[:versionPrefixSize], buf[versionPrefixSize:headSize], buf[headSize:]
+	if !bytes.Equal(prefix, versionPrefix) {
+		return errBadPrefix
 	}
 	fromID, err := recoverNodeID(crypto.Keccak256(buf[headSize:]), sig)
 	if err != nil {
 		return err
 	}
 	pkt.rawData = buf
-	pkt.hash = hash
+	pkt.hash = crypto.Keccak256(buf[versionPrefixSize:])
 	pkt.remoteID = fromID
 	switch pkt.ev = nodeEvent(sigdata[0]); pkt.ev {
 	case pingPacket: