mirror of https://github.com/poanetwork/quorum.git
600 lines
16 KiB
Go
600 lines
16 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package discover
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import (
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"bytes"
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"container/list"
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"crypto/ecdsa"
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"errors"
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"fmt"
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"net"
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"time"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/logger"
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"github.com/ethereum/go-ethereum/logger/glog"
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"github.com/ethereum/go-ethereum/p2p/nat"
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"github.com/ethereum/go-ethereum/rlp"
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)
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const Version = 4
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// Errors
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var (
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errPacketTooSmall = errors.New("too small")
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errBadHash = errors.New("bad hash")
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errExpired = errors.New("expired")
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errUnsolicitedReply = errors.New("unsolicited reply")
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errUnknownNode = errors.New("unknown node")
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errTimeout = errors.New("RPC timeout")
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errClockWarp = errors.New("reply deadline too far in the future")
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errClosed = errors.New("socket closed")
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)
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// Timeouts
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const (
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respTimeout = 500 * time.Millisecond
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sendTimeout = 500 * time.Millisecond
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expiration = 20 * time.Second
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)
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// RPC packet types
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const (
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pingPacket = iota + 1 // zero is 'reserved'
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pongPacket
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findnodePacket
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neighborsPacket
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)
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// RPC request structures
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type (
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ping struct {
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Version uint
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From, To rpcEndpoint
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Expiration uint64
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}
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// pong is the reply to ping.
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pong struct {
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// This field should mirror the UDP envelope address
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// of the ping packet, which provides a way to discover the
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// the external address (after NAT).
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To rpcEndpoint
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ReplyTok []byte // This contains the hash of the ping packet.
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Expiration uint64 // Absolute timestamp at which the packet becomes invalid.
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}
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// findnode is a query for nodes close to the given target.
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findnode struct {
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Target NodeID // doesn't need to be an actual public key
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Expiration uint64
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}
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// reply to findnode
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neighbors struct {
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Nodes []rpcNode
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Expiration uint64
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}
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rpcNode struct {
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IP net.IP // len 4 for IPv4 or 16 for IPv6
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UDP uint16 // for discovery protocol
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TCP uint16 // for RLPx protocol
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ID NodeID
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}
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rpcEndpoint struct {
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IP net.IP // len 4 for IPv4 or 16 for IPv6
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UDP uint16 // for discovery protocol
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TCP uint16 // for RLPx protocol
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}
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)
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func makeEndpoint(addr *net.UDPAddr, tcpPort uint16) rpcEndpoint {
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ip := addr.IP.To4()
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if ip == nil {
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ip = addr.IP.To16()
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}
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return rpcEndpoint{IP: ip, UDP: uint16(addr.Port), TCP: tcpPort}
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}
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func nodeFromRPC(rn rpcNode) (*Node, error) {
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// TODO: don't accept localhost, LAN addresses from internet hosts
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n := NewNode(rn.ID, rn.IP, rn.UDP, rn.TCP)
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err := n.validateComplete()
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return n, err
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}
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func nodeToRPC(n *Node) rpcNode {
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return rpcNode{ID: n.ID, IP: n.IP, UDP: n.UDP, TCP: n.TCP}
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}
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type packet interface {
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handle(t *udp, from *net.UDPAddr, fromID NodeID, mac []byte) error
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}
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type conn interface {
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ReadFromUDP(b []byte) (n int, addr *net.UDPAddr, err error)
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WriteToUDP(b []byte, addr *net.UDPAddr) (n int, err error)
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Close() error
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LocalAddr() net.Addr
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}
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// udp implements the RPC protocol.
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type udp struct {
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conn conn
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priv *ecdsa.PrivateKey
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ourEndpoint rpcEndpoint
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addpending chan *pending
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gotreply chan reply
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closing chan struct{}
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nat nat.Interface
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*Table
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}
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// pending represents a pending reply.
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//
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// some implementations of the protocol wish to send more than one
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// reply packet to findnode. in general, any neighbors packet cannot
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// be matched up with a specific findnode packet.
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//
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// our implementation handles this by storing a callback function for
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// each pending reply. incoming packets from a node are dispatched
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// to all the callback functions for that node.
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type pending struct {
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// these fields must match in the reply.
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from NodeID
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ptype byte
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// time when the request must complete
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deadline time.Time
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// callback is called when a matching reply arrives. if it returns
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// true, the callback is removed from the pending reply queue.
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// if it returns false, the reply is considered incomplete and
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// the callback will be invoked again for the next matching reply.
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callback func(resp interface{}) (done bool)
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// errc receives nil when the callback indicates completion or an
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// error if no further reply is received within the timeout.
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errc chan<- error
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}
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type reply struct {
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from NodeID
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ptype byte
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data interface{}
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// loop indicates whether there was
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// a matching request by sending on this channel.
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matched chan<- bool
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}
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// ListenUDP returns a new table that listens for UDP packets on laddr.
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func ListenUDP(priv *ecdsa.PrivateKey, laddr string, natm nat.Interface, nodeDBPath string) (*Table, error) {
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addr, err := net.ResolveUDPAddr("udp", laddr)
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if err != nil {
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return nil, err
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}
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conn, err := net.ListenUDP("udp", addr)
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if err != nil {
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return nil, err
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}
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tab, _, err := newUDP(priv, conn, natm, nodeDBPath)
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if err != nil {
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return nil, err
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}
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glog.V(logger.Info).Infoln("Listening,", tab.self)
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return tab, nil
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}
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func newUDP(priv *ecdsa.PrivateKey, c conn, natm nat.Interface, nodeDBPath string) (*Table, *udp, error) {
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udp := &udp{
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conn: c,
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priv: priv,
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closing: make(chan struct{}),
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gotreply: make(chan reply),
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addpending: make(chan *pending),
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}
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realaddr := c.LocalAddr().(*net.UDPAddr)
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if natm != nil {
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if !realaddr.IP.IsLoopback() {
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go nat.Map(natm, udp.closing, "udp", realaddr.Port, realaddr.Port, "ethereum discovery")
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}
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// TODO: react to external IP changes over time.
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if ext, err := natm.ExternalIP(); err == nil {
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realaddr = &net.UDPAddr{IP: ext, Port: realaddr.Port}
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}
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}
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// TODO: separate TCP port
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udp.ourEndpoint = makeEndpoint(realaddr, uint16(realaddr.Port))
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tab, err := newTable(udp, PubkeyID(&priv.PublicKey), realaddr, nodeDBPath)
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if err != nil {
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return nil, nil, err
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}
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udp.Table = tab
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go udp.loop()
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go udp.readLoop()
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return udp.Table, udp, nil
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}
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func (t *udp) close() {
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close(t.closing)
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t.conn.Close()
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// TODO: wait for the loops to end.
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}
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// ping sends a ping message to the given node and waits for a reply.
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func (t *udp) ping(toid NodeID, toaddr *net.UDPAddr) error {
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// TODO: maybe check for ReplyTo field in callback to measure RTT
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errc := t.pending(toid, pongPacket, func(interface{}) bool { return true })
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t.send(toaddr, pingPacket, ping{
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Version: Version,
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From: t.ourEndpoint,
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To: makeEndpoint(toaddr, 0), // TODO: maybe use known TCP port from DB
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Expiration: uint64(time.Now().Add(expiration).Unix()),
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})
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return <-errc
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}
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func (t *udp) waitping(from NodeID) error {
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return <-t.pending(from, pingPacket, func(interface{}) bool { return true })
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}
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// findnode sends a findnode request to the given node and waits until
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// the node has sent up to k neighbors.
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func (t *udp) findnode(toid NodeID, toaddr *net.UDPAddr, target NodeID) ([]*Node, error) {
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nodes := make([]*Node, 0, bucketSize)
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nreceived := 0
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errc := t.pending(toid, neighborsPacket, func(r interface{}) bool {
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reply := r.(*neighbors)
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for _, rn := range reply.Nodes {
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nreceived++
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if n, err := nodeFromRPC(rn); err == nil {
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nodes = append(nodes, n)
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}
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}
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return nreceived >= bucketSize
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})
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t.send(toaddr, findnodePacket, findnode{
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Target: target,
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Expiration: uint64(time.Now().Add(expiration).Unix()),
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})
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err := <-errc
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return nodes, err
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}
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// pending adds a reply callback to the pending reply queue.
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// see the documentation of type pending for a detailed explanation.
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func (t *udp) pending(id NodeID, ptype byte, callback func(interface{}) bool) <-chan error {
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ch := make(chan error, 1)
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p := &pending{from: id, ptype: ptype, callback: callback, errc: ch}
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select {
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case t.addpending <- p:
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// loop will handle it
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case <-t.closing:
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ch <- errClosed
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}
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return ch
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}
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func (t *udp) handleReply(from NodeID, ptype byte, req packet) bool {
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matched := make(chan bool, 1)
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select {
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case t.gotreply <- reply{from, ptype, req, matched}:
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// loop will handle it
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return <-matched
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case <-t.closing:
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return false
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}
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}
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// loop runs in its own goroutin. it keeps track of
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// the refresh timer and the pending reply queue.
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func (t *udp) loop() {
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var (
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plist = list.New()
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timeout = time.NewTimer(0)
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nextTimeout *pending // head of plist when timeout was last reset
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)
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<-timeout.C // ignore first timeout
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defer timeout.Stop()
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resetTimeout := func() {
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if plist.Front() == nil || nextTimeout == plist.Front().Value {
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return
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}
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// Start the timer so it fires when the next pending reply has expired.
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now := time.Now()
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for el := plist.Front(); el != nil; el = el.Next() {
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nextTimeout = el.Value.(*pending)
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if dist := nextTimeout.deadline.Sub(now); dist < 2*respTimeout {
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timeout.Reset(dist)
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return
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}
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// Remove pending replies whose deadline is too far in the
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// future. These can occur if the system clock jumped
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// backwards after the deadline was assigned.
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nextTimeout.errc <- errClockWarp
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plist.Remove(el)
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}
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nextTimeout = nil
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timeout.Stop()
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}
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for {
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resetTimeout()
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select {
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case <-t.closing:
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for el := plist.Front(); el != nil; el = el.Next() {
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el.Value.(*pending).errc <- errClosed
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}
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return
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case p := <-t.addpending:
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p.deadline = time.Now().Add(respTimeout)
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plist.PushBack(p)
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case r := <-t.gotreply:
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var matched bool
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for el := plist.Front(); el != nil; el = el.Next() {
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p := el.Value.(*pending)
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if p.from == r.from && p.ptype == r.ptype {
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matched = true
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// Remove the matcher if its callback indicates
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// that all replies have been received. This is
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// required for packet types that expect multiple
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// reply packets.
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if p.callback(r.data) {
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p.errc <- nil
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plist.Remove(el)
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}
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}
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}
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r.matched <- matched
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case now := <-timeout.C:
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nextTimeout = nil
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// Notify and remove callbacks whose deadline is in the past.
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for el := plist.Front(); el != nil; el = el.Next() {
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p := el.Value.(*pending)
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if now.After(p.deadline) || now.Equal(p.deadline) {
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p.errc <- errTimeout
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plist.Remove(el)
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}
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}
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}
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}
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}
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const (
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macSize = 256 / 8
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sigSize = 520 / 8
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headSize = macSize + sigSize // space of packet frame data
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)
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var (
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headSpace = make([]byte, headSize)
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// Neighbors replies are sent across multiple packets to
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// stay below the 1280 byte limit. We compute the maximum number
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// of entries by stuffing a packet until it grows too large.
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maxNeighbors int
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)
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func init() {
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p := neighbors{Expiration: ^uint64(0)}
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maxSizeNode := rpcNode{IP: make(net.IP, 16), UDP: ^uint16(0), TCP: ^uint16(0)}
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for n := 0; ; n++ {
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p.Nodes = append(p.Nodes, maxSizeNode)
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size, _, err := rlp.EncodeToReader(p)
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if err != nil {
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// If this ever happens, it will be caught by the unit tests.
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panic("cannot encode: " + err.Error())
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}
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if headSize+size+1 >= 1280 {
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maxNeighbors = n
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break
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}
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}
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}
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func (t *udp) send(toaddr *net.UDPAddr, ptype byte, req interface{}) error {
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packet, err := encodePacket(t.priv, ptype, req)
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if err != nil {
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return err
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}
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glog.V(logger.Detail).Infof(">>> %v %T\n", toaddr, req)
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if _, err = t.conn.WriteToUDP(packet, toaddr); err != nil {
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glog.V(logger.Detail).Infoln("UDP send failed:", err)
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}
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return err
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}
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func encodePacket(priv *ecdsa.PrivateKey, ptype byte, req interface{}) ([]byte, error) {
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b := new(bytes.Buffer)
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b.Write(headSpace)
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b.WriteByte(ptype)
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if err := rlp.Encode(b, req); err != nil {
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glog.V(logger.Error).Infoln("error encoding packet:", err)
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return nil, err
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}
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packet := b.Bytes()
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sig, err := crypto.Sign(crypto.Sha3(packet[headSize:]), priv)
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if err != nil {
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glog.V(logger.Error).Infoln("could not sign packet:", err)
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return nil, err
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}
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copy(packet[macSize:], sig)
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// add the hash to the front. Note: this doesn't protect the
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// packet in any way. Our public key will be part of this hash in
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// The future.
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copy(packet, crypto.Sha3(packet[macSize:]))
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return packet, nil
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}
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func isTemporaryError(err error) bool {
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tempErr, ok := err.(interface {
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Temporary() bool
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})
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return ok && tempErr.Temporary() || isPacketTooBig(err)
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}
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// readLoop runs in its own goroutine. it handles incoming UDP packets.
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func (t *udp) readLoop() {
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defer t.conn.Close()
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// Discovery packets are defined to be no larger than 1280 bytes.
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// Packets larger than this size will be cut at the end and treated
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// as invalid because their hash won't match.
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buf := make([]byte, 1280)
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for {
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nbytes, from, err := t.conn.ReadFromUDP(buf)
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if isTemporaryError(err) {
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// Ignore temporary read errors.
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glog.V(logger.Debug).Infof("Temporary read error: %v", err)
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continue
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} else if err != nil {
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// Shut down the loop for permament errors.
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glog.V(logger.Debug).Infof("Read error: %v", err)
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return
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}
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t.handlePacket(from, buf[:nbytes])
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}
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}
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func (t *udp) handlePacket(from *net.UDPAddr, buf []byte) error {
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packet, fromID, hash, err := decodePacket(buf)
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if err != nil {
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glog.V(logger.Debug).Infof("Bad packet from %v: %v\n", from, err)
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return err
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}
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status := "ok"
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if err = packet.handle(t, from, fromID, hash); err != nil {
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status = err.Error()
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}
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glog.V(logger.Detail).Infof("<<< %v %T: %s\n", from, packet, status)
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return err
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}
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func decodePacket(buf []byte) (packet, NodeID, []byte, error) {
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if len(buf) < headSize+1 {
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return nil, NodeID{}, nil, errPacketTooSmall
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}
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hash, sig, sigdata := buf[:macSize], buf[macSize:headSize], buf[headSize:]
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shouldhash := crypto.Sha3(buf[macSize:])
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if !bytes.Equal(hash, shouldhash) {
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return nil, NodeID{}, nil, errBadHash
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}
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fromID, err := recoverNodeID(crypto.Sha3(buf[headSize:]), sig)
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if err != nil {
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return nil, NodeID{}, hash, err
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}
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var req packet
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switch ptype := sigdata[0]; ptype {
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case pingPacket:
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req = new(ping)
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case pongPacket:
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req = new(pong)
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case findnodePacket:
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req = new(findnode)
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case neighborsPacket:
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req = new(neighbors)
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default:
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return nil, fromID, hash, fmt.Errorf("unknown type: %d", ptype)
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}
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err = rlp.DecodeBytes(sigdata[1:], req)
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return req, fromID, hash, err
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}
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|
|
|
func (req *ping) handle(t *udp, from *net.UDPAddr, fromID NodeID, mac []byte) error {
|
|
if expired(req.Expiration) {
|
|
return errExpired
|
|
}
|
|
t.send(from, pongPacket, pong{
|
|
To: makeEndpoint(from, req.From.TCP),
|
|
ReplyTok: mac,
|
|
Expiration: uint64(time.Now().Add(expiration).Unix()),
|
|
})
|
|
if !t.handleReply(fromID, pingPacket, req) {
|
|
// Note: we're ignoring the provided IP address right now
|
|
go t.bond(true, fromID, from, req.From.TCP)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (req *pong) handle(t *udp, from *net.UDPAddr, fromID NodeID, mac []byte) error {
|
|
if expired(req.Expiration) {
|
|
return errExpired
|
|
}
|
|
if !t.handleReply(fromID, pongPacket, req) {
|
|
return errUnsolicitedReply
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (req *findnode) handle(t *udp, from *net.UDPAddr, fromID NodeID, mac []byte) error {
|
|
if expired(req.Expiration) {
|
|
return errExpired
|
|
}
|
|
if t.db.node(fromID) == nil {
|
|
// No bond exists, we don't process the packet. This prevents
|
|
// an attack vector where the discovery protocol could be used
|
|
// to amplify traffic in a DDOS attack. A malicious actor
|
|
// would send a findnode request with the IP address and UDP
|
|
// port of the target as the source address. The recipient of
|
|
// the findnode packet would then send a neighbors packet
|
|
// (which is a much bigger packet than findnode) to the victim.
|
|
return errUnknownNode
|
|
}
|
|
target := crypto.Sha3Hash(req.Target[:])
|
|
t.mutex.Lock()
|
|
closest := t.closest(target, bucketSize).entries
|
|
t.mutex.Unlock()
|
|
|
|
p := neighbors{Expiration: uint64(time.Now().Add(expiration).Unix())}
|
|
// Send neighbors in chunks with at most maxNeighbors per packet
|
|
// to stay below the 1280 byte limit.
|
|
for i, n := range closest {
|
|
p.Nodes = append(p.Nodes, nodeToRPC(n))
|
|
if len(p.Nodes) == maxNeighbors || i == len(closest)-1 {
|
|
t.send(from, neighborsPacket, p)
|
|
p.Nodes = p.Nodes[:0]
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (req *neighbors) handle(t *udp, from *net.UDPAddr, fromID NodeID, mac []byte) error {
|
|
if expired(req.Expiration) {
|
|
return errExpired
|
|
}
|
|
if !t.handleReply(fromID, neighborsPacket, req) {
|
|
return errUnsolicitedReply
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func expired(ts uint64) bool {
|
|
return time.Unix(int64(ts), 0).Before(time.Now())
|
|
}
|