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-rw-r--r--p2p/discv5/udp.go456
1 files changed, 456 insertions, 0 deletions
diff --git a/p2p/discv5/udp.go b/p2p/discv5/udp.go
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+++ b/p2p/discv5/udp.go
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+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library 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 Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package discv5
+
+import (
+ "bytes"
+ "crypto/ecdsa"
+ "errors"
+ "fmt"
+ "net"
+ "time"
+
+ "github.com/ethereum/go-ethereum/common"
+ "github.com/ethereum/go-ethereum/crypto"
+ "github.com/ethereum/go-ethereum/logger"
+ "github.com/ethereum/go-ethereum/logger/glog"
+ "github.com/ethereum/go-ethereum/p2p/nat"
+ "github.com/ethereum/go-ethereum/rlp"
+)
+
+const Version = 4
+
+// Errors
+var (
+ errPacketTooSmall = errors.New("too small")
+ errBadHash = errors.New("bad hash")
+ errExpired = errors.New("expired")
+ errUnsolicitedReply = errors.New("unsolicited reply")
+ errUnknownNode = errors.New("unknown node")
+ errTimeout = errors.New("RPC timeout")
+ errClockWarp = errors.New("reply deadline too far in the future")
+ errClosed = errors.New("socket closed")
+)
+
+// Timeouts
+const (
+ respTimeout = 500 * time.Millisecond
+ sendTimeout = 500 * time.Millisecond
+ expiration = 20 * time.Second
+
+ ntpFailureThreshold = 32 // Continuous timeouts after which to check NTP
+ ntpWarningCooldown = 10 * time.Minute // Minimum amount of time to pass before repeating NTP warning
+ driftThreshold = 10 * time.Second // Allowed clock drift before warning user
+)
+
+// RPC request structures
+type (
+ ping struct {
+ Version uint
+ From, To rpcEndpoint
+ Expiration uint64
+
+ // v5
+ Topics []Topic
+
+ // Ignore additional fields (for forward compatibility).
+ Rest []rlp.RawValue `rlp:"tail"`
+ }
+
+ // pong is the reply to ping.
+ pong struct {
+ // This field should mirror the UDP envelope address
+ // of the ping packet, which provides a way to discover the
+ // the external address (after NAT).
+ To rpcEndpoint
+
+ ReplyTok []byte // This contains the hash of the ping packet.
+ Expiration uint64 // Absolute timestamp at which the packet becomes invalid.
+
+ // v5
+ TopicHash common.Hash
+ TicketSerial uint32
+ WaitPeriods []uint32
+
+ // Ignore additional fields (for forward compatibility).
+ Rest []rlp.RawValue `rlp:"tail"`
+ }
+
+ // findnode is a query for nodes close to the given target.
+ findnode struct {
+ Target NodeID // doesn't need to be an actual public key
+ Expiration uint64
+ // Ignore additional fields (for forward compatibility).
+ Rest []rlp.RawValue `rlp:"tail"`
+ }
+
+ // findnode is a query for nodes close to the given target.
+ findnodeHash struct {
+ Target common.Hash
+ Expiration uint64
+ // Ignore additional fields (for forward compatibility).
+ Rest []rlp.RawValue `rlp:"tail"`
+ }
+
+ // reply to findnode
+ neighbors struct {
+ Nodes []rpcNode
+ Expiration uint64
+ // Ignore additional fields (for forward compatibility).
+ Rest []rlp.RawValue `rlp:"tail"`
+ }
+
+ topicRegister struct {
+ Topics []Topic
+ Idx uint
+ Pong []byte
+ }
+
+ topicQuery struct {
+ Topic Topic
+ Expiration uint64
+ }
+
+ // reply to topicQuery
+ topicNodes struct {
+ Echo common.Hash
+ Nodes []rpcNode
+ }
+
+ rpcNode struct {
+ IP net.IP // len 4 for IPv4 or 16 for IPv6
+ UDP uint16 // for discovery protocol
+ TCP uint16 // for RLPx protocol
+ ID NodeID
+ }
+
+ rpcEndpoint struct {
+ IP net.IP // len 4 for IPv4 or 16 for IPv6
+ UDP uint16 // for discovery protocol
+ TCP uint16 // for RLPx protocol
+ }
+)
+
+const (
+ macSize = 256 / 8
+ sigSize = 520 / 8
+ headSize = macSize + sigSize // space of packet frame data
+)
+
+// Neighbors replies are sent across multiple packets to
+// stay below the 1280 byte limit. We compute the maximum number
+// of entries by stuffing a packet until it grows too large.
+var maxNeighbors = func() int {
+ p := neighbors{Expiration: ^uint64(0)}
+ maxSizeNode := rpcNode{IP: make(net.IP, 16), UDP: ^uint16(0), TCP: ^uint16(0)}
+ for n := 0; ; n++ {
+ p.Nodes = append(p.Nodes, maxSizeNode)
+ size, _, err := rlp.EncodeToReader(p)
+ if err != nil {
+ // If this ever happens, it will be caught by the unit tests.
+ panic("cannot encode: " + err.Error())
+ }
+ if headSize+size+1 >= 1280 {
+ return n
+ }
+ }
+}()
+
+var maxTopicNodes = func() int {
+ p := topicNodes{}
+ maxSizeNode := rpcNode{IP: make(net.IP, 16), UDP: ^uint16(0), TCP: ^uint16(0)}
+ for n := 0; ; n++ {
+ p.Nodes = append(p.Nodes, maxSizeNode)
+ size, _, err := rlp.EncodeToReader(p)
+ if err != nil {
+ // If this ever happens, it will be caught by the unit tests.
+ panic("cannot encode: " + err.Error())
+ }
+ if headSize+size+1 >= 1280 {
+ return n
+ }
+ }
+}()
+
+func makeEndpoint(addr *net.UDPAddr, tcpPort uint16) rpcEndpoint {
+ ip := addr.IP.To4()
+ if ip == nil {
+ ip = addr.IP.To16()
+ }
+ return rpcEndpoint{IP: ip, UDP: uint16(addr.Port), TCP: tcpPort}
+}
+
+func (e1 rpcEndpoint) equal(e2 rpcEndpoint) bool {
+ return e1.UDP == e2.UDP && e1.TCP == e2.TCP && bytes.Equal(e1.IP, e2.IP)
+}
+
+func nodeFromRPC(rn rpcNode) (*Node, error) {
+ // TODO: don't accept localhost, LAN addresses from internet hosts
+ n := NewNode(rn.ID, rn.IP, rn.UDP, rn.TCP)
+ err := n.validateComplete()
+ return n, err
+}
+
+func nodeToRPC(n *Node) rpcNode {
+ return rpcNode{ID: n.ID, IP: n.IP, UDP: n.UDP, TCP: n.TCP}
+}
+
+type ingressPacket struct {
+ remoteID NodeID
+ remoteAddr *net.UDPAddr
+ ev nodeEvent
+ hash []byte
+ data interface{} // one of the RPC structs
+ rawData []byte
+}
+
+type conn interface {
+ ReadFromUDP(b []byte) (n int, addr *net.UDPAddr, err error)
+ WriteToUDP(b []byte, addr *net.UDPAddr) (n int, err error)
+ Close() error
+ LocalAddr() net.Addr
+}
+
+// udp implements the RPC protocol.
+type udp struct {
+ conn conn
+ priv *ecdsa.PrivateKey
+ ourEndpoint rpcEndpoint
+ nat nat.Interface
+ net *Network
+}
+
+// ListenUDP returns a new table that listens for UDP packets on laddr.
+func ListenUDP(priv *ecdsa.PrivateKey, laddr string, natm nat.Interface, nodeDBPath string) (*Network, error) {
+ transport, err := listenUDP(priv, laddr)
+ if err != nil {
+ return nil, err
+ }
+ net, err := newNetwork(transport, priv.PublicKey, natm, nodeDBPath)
+ if err != nil {
+ return nil, err
+ }
+ transport.net = net
+ go transport.readLoop()
+ 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 (t *udp) localAddr() *net.UDPAddr {
+ return t.conn.LocalAddr().(*net.UDPAddr)
+}
+
+func (t *udp) Close() {
+ t.conn.Close()
+}
+
+func (t *udp) send(remote *Node, ptype nodeEvent, data interface{}) (hash []byte) {
+ hash, _ = t.sendPacket(remote.ID, remote.addr(), byte(ptype), data)
+ return hash
+}
+
+func (t *udp) sendPing(remote *Node, toaddr *net.UDPAddr, topics []Topic) (hash []byte) {
+ hash, _ = t.sendPacket(remote.ID, toaddr, byte(pingPacket), ping{
+ Version: Version,
+ From: t.ourEndpoint,
+ To: makeEndpoint(toaddr, uint16(toaddr.Port)), // TODO: maybe use known TCP port from DB
+ Expiration: uint64(time.Now().Add(expiration).Unix()),
+ Topics: topics,
+ })
+ return hash
+}
+
+func (t *udp) sendFindnode(remote *Node, target NodeID) {
+ t.sendPacket(remote.ID, remote.addr(), byte(findnodePacket), findnode{
+ Target: target,
+ Expiration: uint64(time.Now().Add(expiration).Unix()),
+ })
+}
+
+func (t *udp) sendNeighbours(remote *Node, results []*Node) {
+ // Send neighbors in chunks with at most maxNeighbors per packet
+ // to stay below the 1280 byte limit.
+ p := neighbors{Expiration: uint64(time.Now().Add(expiration).Unix())}
+ for i, result := range results {
+ p.Nodes = append(p.Nodes, nodeToRPC(result))
+ if len(p.Nodes) == maxNeighbors || i == len(results)-1 {
+ t.sendPacket(remote.ID, remote.addr(), byte(neighborsPacket), p)
+ p.Nodes = p.Nodes[:0]
+ }
+ }
+}
+
+func (t *udp) sendFindnodeHash(remote *Node, target common.Hash) {
+ t.sendPacket(remote.ID, remote.addr(), byte(findnodeHashPacket), findnodeHash{
+ Target: target,
+ Expiration: uint64(time.Now().Add(expiration).Unix()),
+ })
+}
+
+func (t *udp) sendTopicRegister(remote *Node, topics []Topic, idx int, pong []byte) {
+ t.sendPacket(remote.ID, remote.addr(), byte(topicRegisterPacket), topicRegister{
+ Topics: topics,
+ Idx: uint(idx),
+ Pong: pong,
+ })
+}
+
+func (t *udp) sendTopicNodes(remote *Node, queryHash common.Hash, nodes []*Node) {
+ p := topicNodes{Echo: queryHash}
+ if len(nodes) == 0 {
+ t.sendPacket(remote.ID, remote.addr(), byte(topicNodesPacket), p)
+ return
+ }
+ for i, result := range nodes {
+ p.Nodes = append(p.Nodes, nodeToRPC(result))
+ if len(p.Nodes) == maxTopicNodes || i == len(nodes)-1 {
+ t.sendPacket(remote.ID, remote.addr(), byte(topicNodesPacket), p)
+ p.Nodes = p.Nodes[:0]
+ }
+ }
+}
+
+func (t *udp) sendPacket(toid NodeID, toaddr *net.UDPAddr, ptype byte, req interface{}) (hash []byte, err error) {
+ packet, hash, err := encodePacket(t.priv, ptype, req)
+ if err != nil {
+ return hash, err
+ }
+ glog.V(logger.Detail).Infof(">>> %v to %x@%v\n", nodeEvent(ptype), toid[:8], toaddr)
+ if _, err = t.conn.WriteToUDP(packet, toaddr); err != nil {
+ glog.V(logger.Detail).Infoln("UDP send failed:", err)
+ }
+ return hash, err
+}
+
+// zeroed padding space for encodePacket.
+var headSpace = make([]byte, headSize)
+
+func encodePacket(priv *ecdsa.PrivateKey, ptype byte, req interface{}) (p, hash []byte, err error) {
+ b := new(bytes.Buffer)
+ b.Write(headSpace)
+ b.WriteByte(ptype)
+ if err := rlp.Encode(b, req); err != nil {
+ glog.V(logger.Error).Infoln("error encoding packet:", err)
+ return nil, nil, err
+ }
+ packet := b.Bytes()
+ sig, err := crypto.Sign(crypto.Keccak256(packet[headSize:]), priv)
+ if err != nil {
+ glog.V(logger.Error).Infoln("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)
+ return packet, hash, nil
+}
+
+// readLoop runs in its own goroutine. it injects ingress UDP packets
+// into the network loop.
+func (t *udp) readLoop() {
+ defer t.conn.Close()
+ // 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.
+ buf := make([]byte, 1280)
+ for {
+ nbytes, from, err := t.conn.ReadFromUDP(buf)
+ if isTemporaryError(err) {
+ // Ignore temporary read errors.
+ glog.V(logger.Debug).Infof("Temporary read error: %v", err)
+ continue
+ } else if err != nil {
+ // Shut down the loop for permament errors.
+ glog.V(logger.Debug).Infof("Read error: %v", err)
+ return
+ }
+ t.handlePacket(from, buf[:nbytes])
+ }
+}
+
+func isTemporaryError(err error) bool {
+ tempErr, ok := err.(interface {
+ Temporary() bool
+ })
+ return ok && tempErr.Temporary() || isPacketTooBig(err)
+}
+
+func (t *udp) handlePacket(from *net.UDPAddr, buf []byte) error {
+ pkt := ingressPacket{remoteAddr: from}
+ if err := decodePacket(buf, &pkt); err != nil {
+ glog.V(logger.Debug).Infof("Bad packet from %v: %v\n", from, err)
+ return err
+ }
+ t.net.reqReadPacket(pkt)
+ return nil
+}
+
+func decodePacket(buffer []byte, pkt *ingressPacket) error {
+ if len(buffer) < headSize+1 {
+ return errPacketTooSmall
+ }
+ 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
+ }
+ fromID, err := recoverNodeID(crypto.Keccak256(buf[headSize:]), sig)
+ if err != nil {
+ return err
+ }
+ pkt.rawData = buf
+ pkt.hash = hash
+ pkt.remoteID = fromID
+ switch pkt.ev = nodeEvent(sigdata[0]); pkt.ev {
+ case pingPacket:
+ pkt.data = new(ping)
+ case pongPacket:
+ pkt.data = new(pong)
+ case findnodePacket:
+ pkt.data = new(findnode)
+ case neighborsPacket:
+ pkt.data = new(neighbors)
+ case findnodeHashPacket:
+ pkt.data = new(findnodeHash)
+ case topicRegisterPacket:
+ pkt.data = new(topicRegister)
+ case topicQueryPacket:
+ pkt.data = new(topicQuery)
+ case topicNodesPacket:
+ pkt.data = new(topicNodes)
+ default:
+ return fmt.Errorf("unknown packet type: %d", sigdata[0])
+ }
+ s := rlp.NewStream(bytes.NewReader(sigdata[1:]), 0)
+ err = s.Decode(pkt.data)
+ return err
+}
generated by cgit (git 2.34.1) at 2024-11-15 12:12:38 +0800