p2p/discover: split out discv4 code
This change restructures the internals of p2p/discover to make room for the discv5 code which will soon be added to this package. - packet type names now have a "V4" suffix. - ListenUDP returns *UDPv4 instead of *Table. This technically breaks the API but the only caller in go-ethereum is package p2p, which uses a compatible interface and doesn't need changes. - The internal transport interface is changed to make Table reusable for v5. - The 'lookup' code moves from table to transport. This required updating the lookup unit test to use udpTest instead of a custom transport.
This commit is contained in:
Felix Lange
870
p2p/discover/v4_udp.go
Normal file
870
p2p/discover/v4_udp.go
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@ -0,0 +1,870 @@
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// 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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crand "crypto/rand"
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"errors"
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"fmt"
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"io"
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"net"
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"sync"
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"time"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/log"
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"github.com/ethereum/go-ethereum/p2p/enode"
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"github.com/ethereum/go-ethereum/p2p/netutil"
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"github.com/ethereum/go-ethereum/rlp"
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)
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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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expiration = 20 * time.Second
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bondExpiration = 24 * time.Hour
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ntpFailureThreshold = 32 // Continuous timeouts after which to check NTP
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ntpWarningCooldown = 10 * time.Minute // Minimum amount of time to pass before repeating NTP warning
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driftThreshold = 10 * time.Second // Allowed clock drift before warning user
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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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maxPacketSize = 1280
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)
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// RPC packet types
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const (
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p_pingV4 = iota + 1 // zero is 'reserved'
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p_pongV4
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p_findnodeV4
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p_neighborsV4
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)
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// RPC request structures
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type (
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pingV4 struct {
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senderKey *ecdsa.PublicKey // filled in by preverify
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Version uint
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From, To rpcEndpoint
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Expiration uint64
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// Ignore additional fields (for forward compatibility).
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Rest []rlp.RawValue `rlp:"tail"`
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}
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// pongV4 is the reply to pingV4.
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pongV4 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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// Ignore additional fields (for forward compatibility).
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Rest []rlp.RawValue `rlp:"tail"`
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}
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// findnodeV4 is a query for nodes close to the given target.
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findnodeV4 struct {
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Target encPubkey
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Expiration uint64
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// Ignore additional fields (for forward compatibility).
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Rest []rlp.RawValue `rlp:"tail"`
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}
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// neighborsV4 is the reply to findnodeV4.
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neighborsV4 struct {
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Nodes []rpcNode
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Expiration uint64
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// Ignore additional fields (for forward compatibility).
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Rest []rlp.RawValue `rlp:"tail"`
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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 encPubkey
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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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// packet is implemented by all v4 protocol messages.
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type packetV4 interface {
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// preverify checks whether the packet is valid and should be handled at all.
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preverify(t *UDPv4, from *net.UDPAddr, fromID enode.ID, fromKey encPubkey) error
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// handle handles the packet.
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handle(t *UDPv4, from *net.UDPAddr, fromID enode.ID, mac []byte)
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// name returns the name of the packet for logging purposes.
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name() string
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}
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func makeEndpoint(addr *net.UDPAddr, tcpPort uint16) rpcEndpoint {
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ip := net.IP{}
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if ip4 := addr.IP.To4(); ip4 != nil {
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ip = ip4
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} else if ip6 := addr.IP.To16(); ip6 != nil {
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ip = ip6
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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 (t *UDPv4) nodeFromRPC(sender *net.UDPAddr, rn rpcNode) (*node, error) {
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if rn.UDP <= 1024 {
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return nil, errors.New("low port")
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}
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if err := netutil.CheckRelayIP(sender.IP, rn.IP); err != nil {
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return nil, err
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}
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if t.netrestrict != nil && !t.netrestrict.Contains(rn.IP) {
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return nil, errors.New("not contained in netrestrict whitelist")
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}
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key, err := decodePubkey(rn.ID)
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if err != nil {
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return nil, err
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}
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n := wrapNode(enode.NewV4(key, rn.IP, int(rn.TCP), int(rn.UDP)))
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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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var key ecdsa.PublicKey
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var ekey encPubkey
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if err := n.Load((*enode.Secp256k1)(&key)); err == nil {
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ekey = encodePubkey(&key)
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}
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return rpcNode{ID: ekey, IP: n.IP(), UDP: uint16(n.UDP()), TCP: uint16(n.TCP())}
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}
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// UDPv4 implements the v4 wire protocol.
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type UDPv4 struct {
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conn UDPConn
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log log.Logger
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netrestrict *netutil.Netlist
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priv *ecdsa.PrivateKey
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localNode *enode.LocalNode
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db *enode.DB
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tab *Table
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closeOnce sync.Once
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wg sync.WaitGroup
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addReplyMatcher chan *replyMatcher
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gotreply chan reply
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closing chan struct{}
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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 callback functions for that node.
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type replyMatcher struct {
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// these fields must match in the reply.
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from enode.ID
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ip net.IP
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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 matched == true, the
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// reply was acceptable. The second return value indicates whether the callback should
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// be removed from the pending reply queue. If it returns false, the reply is considered
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// incomplete and the callback will be invoked again for the next matching reply.
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callback replyMatchFunc
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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 replyMatchFunc func(interface{}) (matched bool, requestDone bool)
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type reply struct {
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from enode.ID
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ip net.IP
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ptype byte
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data packetV4
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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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func ListenV4(c UDPConn, ln *enode.LocalNode, cfg Config) (*UDPv4, error) {
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t := &UDPv4{
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conn: c,
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priv: cfg.PrivateKey,
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netrestrict: cfg.NetRestrict,
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localNode: ln,
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db: ln.Database(),
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closing: make(chan struct{}),
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gotreply: make(chan reply),
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addReplyMatcher: make(chan *replyMatcher),
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log: cfg.Log,
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}
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if t.log == nil {
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t.log = log.Root()
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}
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tab, err := newTable(t, ln.Database(), cfg.Bootnodes, t.log)
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if err != nil {
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return nil, err
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}
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t.tab = tab
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t.wg.Add(2)
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go t.loop()
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go t.readLoop(cfg.Unhandled)
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return t, nil
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}
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// Self returns the local node.
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func (t *UDPv4) Self() *enode.Node {
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return t.localNode.Node()
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}
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// Close shuts down the socket and aborts any running queries.
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func (t *UDPv4) Close() {
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t.closeOnce.Do(func() {
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close(t.closing)
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t.conn.Close()
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t.wg.Wait()
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t.tab.close()
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})
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}
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// ReadRandomNodes reads random nodes from the local table.
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func (t *UDPv4) ReadRandomNodes(buf []*enode.Node) int {
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return t.tab.ReadRandomNodes(buf)
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}
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// LookupRandom finds random nodes in the network.
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func (t *UDPv4) LookupRandom() []*enode.Node {
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if t.tab.len() == 0 {
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// All nodes were dropped, refresh. The very first query will hit this
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// case and run the bootstrapping logic.
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<-t.tab.refresh()
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}
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return t.lookupRandom()
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}
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func (t *UDPv4) LookupPubkey(key *ecdsa.PublicKey) []*enode.Node {
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if t.tab.len() == 0 {
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// All nodes were dropped, refresh. The very first query will hit this
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// case and run the bootstrapping logic.
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<-t.tab.refresh()
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}
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return unwrapNodes(t.lookup(encodePubkey(key)))
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}
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func (t *UDPv4) lookupRandom() []*enode.Node {
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var target encPubkey
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crand.Read(target[:])
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return unwrapNodes(t.lookup(target))
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}
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func (t *UDPv4) lookupSelf() []*enode.Node {
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return unwrapNodes(t.lookup(encodePubkey(&t.priv.PublicKey)))
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}
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// lookup performs a network search for nodes close to the given target. It approaches the
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// target by querying nodes that are closer to it on each iteration. The given target does
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// not need to be an actual node identifier.
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func (t *UDPv4) lookup(targetKey encPubkey) []*node {
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var (
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target = enode.ID(crypto.Keccak256Hash(targetKey[:]))
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asked = make(map[enode.ID]bool)
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seen = make(map[enode.ID]bool)
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reply = make(chan []*node, alpha)
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pendingQueries = 0
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result *nodesByDistance
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)
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// Don't query further if we hit ourself.
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// Unlikely to happen often in practice.
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asked[t.Self().ID()] = true
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// Generate the initial result set.
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t.tab.mutex.Lock()
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result = t.tab.closest(target, bucketSize, false)
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t.tab.mutex.Unlock()
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for {
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// ask the alpha closest nodes that we haven't asked yet
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for i := 0; i < len(result.entries) && pendingQueries < alpha; i++ {
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n := result.entries[i]
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if !asked[n.ID()] {
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asked[n.ID()] = true
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pendingQueries++
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go t.lookupWorker(n, targetKey, reply)
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}
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}
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if pendingQueries == 0 {
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// we have asked all closest nodes, stop the search
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break
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}
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select {
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case nodes := <-reply:
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for _, n := range nodes {
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if n != nil && !seen[n.ID()] {
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seen[n.ID()] = true
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result.push(n, bucketSize)
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}
|
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}
|
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case <-t.tab.closeReq:
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return nil // shutdown, no need to continue.
|
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}
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pendingQueries--
|
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}
|
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return result.entries
|
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}
|
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|
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func (t *UDPv4) lookupWorker(n *node, targetKey encPubkey, reply chan<- []*node) {
|
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fails := t.db.FindFails(n.ID(), n.IP())
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r, err := t.findnode(n.ID(), n.addr(), targetKey)
|
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if err == errClosed {
|
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// Avoid recording failures on shutdown.
|
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reply <- nil
|
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return
|
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} else if len(r) == 0 {
|
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fails++
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t.db.UpdateFindFails(n.ID(), n.IP(), fails)
|
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t.log.Trace("Findnode failed", "id", n.ID(), "failcount", fails, "err", err)
|
||||
if fails >= maxFindnodeFailures {
|
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t.log.Trace("Too many findnode failures, dropping", "id", n.ID(), "failcount", fails)
|
||||
t.tab.delete(n)
|
||||
}
|
||||
} else if fails > 0 {
|
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t.db.UpdateFindFails(n.ID(), n.IP(), fails-1)
|
||||
}
|
||||
|
||||
// Grab as many nodes as possible. Some of them might not be alive anymore, but we'll
|
||||
// just remove those again during revalidation.
|
||||
for _, n := range r {
|
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t.tab.addSeenNode(n)
|
||||
}
|
||||
reply <- r
|
||||
}
|
||||
|
||||
// Resolve searches for a specific node with the given ID.
|
||||
// It returns nil if the node could not be found.
|
||||
func (t *UDPv4) Resolve(n *enode.Node) *enode.Node {
|
||||
// If the node is present in the local table, no
|
||||
// network interaction is required.
|
||||
if intab := t.tab.Resolve(n); intab != nil {
|
||||
return intab
|
||||
}
|
||||
// Otherwise, do a network lookup.
|
||||
hash := n.ID()
|
||||
result := t.LookupPubkey(n.Pubkey())
|
||||
for _, n := range result {
|
||||
if n.ID() == hash {
|
||||
return n
|
||||
}
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func (t *UDPv4) ourEndpoint() rpcEndpoint {
|
||||
n := t.Self()
|
||||
a := &net.UDPAddr{IP: n.IP(), Port: n.UDP()}
|
||||
return makeEndpoint(a, uint16(n.TCP()))
|
||||
}
|
||||
|
||||
// ping sends a ping message to the given node and waits for a reply.
|
||||
func (t *UDPv4) ping(n *enode.Node) error {
|
||||
return <-t.sendPing(n.ID(), &net.UDPAddr{IP: n.IP(), Port: n.UDP()}, nil)
|
||||
}
|
||||
|
||||
// sendPing sends a ping message to the given node and invokes the callback
|
||||
// when the reply arrives.
|
||||
func (t *UDPv4) sendPing(toid enode.ID, toaddr *net.UDPAddr, callback func()) <-chan error {
|
||||
req := &pingV4{
|
||||
Version: 4,
|
||||
From: t.ourEndpoint(),
|
||||
To: makeEndpoint(toaddr, 0), // TODO: maybe use known TCP port from DB
|
||||
Expiration: uint64(time.Now().Add(expiration).Unix()),
|
||||
}
|
||||
packet, hash, err := t.encode(t.priv, p_pingV4, req)
|
||||
if err != nil {
|
||||
errc := make(chan error, 1)
|
||||
errc <- err
|
||||
return errc
|
||||
}
|
||||
// Add a matcher for the reply to the pending reply queue. Pongs are matched if they
|
||||
// reference the ping we're about to send.
|
||||
errc := t.pending(toid, toaddr.IP, p_pongV4, func(p interface{}) (matched bool, requestDone bool) {
|
||||
matched = bytes.Equal(p.(*pongV4).ReplyTok, hash)
|
||||
if matched && callback != nil {
|
||||
callback()
|
||||
}
|
||||
return matched, matched
|
||||
})
|
||||
// Send the packet.
|
||||
t.localNode.UDPContact(toaddr)
|
||||
t.write(toaddr, toid, req.name(), packet)
|
||||
return errc
|
||||
}
|
||||
|
||||
// findnode sends a findnode request to the given node and waits until
|
||||
// the node has sent up to k neighbors.
|
||||
func (t *UDPv4) findnode(toid enode.ID, toaddr *net.UDPAddr, target encPubkey) ([]*node, error) {
|
||||
// If we haven't seen a ping from the destination node for a while, it won't remember
|
||||
// our endpoint proof and reject findnode. Solicit a ping first.
|
||||
if time.Since(t.db.LastPingReceived(toid, toaddr.IP)) > bondExpiration {
|
||||
<-t.sendPing(toid, toaddr, nil)
|
||||
// Wait for them to ping back and process our pong.
|
||||
time.Sleep(respTimeout)
|
||||
}
|
||||
|
||||
// Add a matcher for 'neighbours' replies to the pending reply queue. The matcher is
|
||||
// active until enough nodes have been received.
|
||||
nodes := make([]*node, 0, bucketSize)
|
||||
nreceived := 0
|
||||
errc := t.pending(toid, toaddr.IP, p_neighborsV4, func(r interface{}) (matched bool, requestDone bool) {
|
||||
reply := r.(*neighborsV4)
|
||||
for _, rn := range reply.Nodes {
|
||||
nreceived++
|
||||
n, err := t.nodeFromRPC(toaddr, rn)
|
||||
if err != nil {
|
||||
t.log.Trace("Invalid neighbor node received", "ip", rn.IP, "addr", toaddr, "err", err)
|
||||
continue
|
||||
}
|
||||
nodes = append(nodes, n)
|
||||
}
|
||||
return true, nreceived >= bucketSize
|
||||
})
|
||||
t.send(toaddr, toid, p_findnodeV4, &findnodeV4{
|
||||
Target: target,
|
||||
Expiration: uint64(time.Now().Add(expiration).Unix()),
|
||||
})
|
||||
return nodes, <-errc
|
||||
}
|
||||
|
||||
// pending adds a reply matcher to the pending reply queue.
|
||||
// see the documentation of type replyMatcher for a detailed explanation.
|
||||
func (t *UDPv4) pending(id enode.ID, ip net.IP, ptype byte, callback replyMatchFunc) <-chan error {
|
||||
ch := make(chan error, 1)
|
||||
p := &replyMatcher{from: id, ip: ip, ptype: ptype, callback: callback, errc: ch}
|
||||
select {
|
||||
case t.addReplyMatcher <- p:
|
||||
// loop will handle it
|
||||
case <-t.closing:
|
||||
ch <- errClosed
|
||||
}
|
||||
return ch
|
||||
}
|
||||
|
||||
// handleReply dispatches a reply packet, invoking reply matchers. It returns
|
||||
// whether any matcher considered the packet acceptable.
|
||||
func (t *UDPv4) handleReply(from enode.ID, fromIP net.IP, ptype byte, req packetV4) bool {
|
||||
matched := make(chan bool, 1)
|
||||
select {
|
||||
case t.gotreply <- reply{from, fromIP, ptype, req, matched}:
|
||||
// loop will handle it
|
||||
return <-matched
|
||||
case <-t.closing:
|
||||
return false
|
||||
}
|
||||
}
|
||||
|
||||
// loop runs in its own goroutine. it keeps track of
|
||||
// the refresh timer and the pending reply queue.
|
||||
func (t *UDPv4) loop() {
|
||||
defer t.wg.Done()
|
||||
|
||||
var (
|
||||
plist = list.New()
|
||||
timeout = time.NewTimer(0)
|
||||
nextTimeout *replyMatcher // head of plist when timeout was last reset
|
||||
contTimeouts = 0 // number of continuous timeouts to do NTP checks
|
||||
ntpWarnTime = time.Unix(0, 0)
|
||||
)
|
||||
<-timeout.C // ignore first timeout
|
||||
defer timeout.Stop()
|
||||
|
||||
resetTimeout := func() {
|
||||
if plist.Front() == nil || nextTimeout == plist.Front().Value {
|
||||
return
|
||||
}
|
||||
// Start the timer so it fires when the next pending reply has expired.
|
||||
now := time.Now()
|
||||
for el := plist.Front(); el != nil; el = el.Next() {
|
||||
nextTimeout = el.Value.(*replyMatcher)
|
||||
if dist := nextTimeout.deadline.Sub(now); dist < 2*respTimeout {
|
||||
timeout.Reset(dist)
|
||||
return
|
||||
}
|
||||
// Remove pending replies whose deadline is too far in the
|
||||
// future. These can occur if the system clock jumped
|
||||
// backwards after the deadline was assigned.
|
||||
nextTimeout.errc <- errClockWarp
|
||||
plist.Remove(el)
|
||||
}
|
||||
nextTimeout = nil
|
||||
timeout.Stop()
|
||||
}
|
||||
|
||||
for {
|
||||
resetTimeout()
|
||||
|
||||
select {
|
||||
case <-t.closing:
|
||||
for el := plist.Front(); el != nil; el = el.Next() {
|
||||
el.Value.(*replyMatcher).errc <- errClosed
|
||||
}
|
||||
return
|
||||
|
||||
case p := <-t.addReplyMatcher:
|
||||
p.deadline = time.Now().Add(respTimeout)
|
||||
plist.PushBack(p)
|
||||
|
||||
case r := <-t.gotreply:
|
||||
var matched bool // whether any replyMatcher considered the reply acceptable.
|
||||
for el := plist.Front(); el != nil; el = el.Next() {
|
||||
p := el.Value.(*replyMatcher)
|
||||
if p.from == r.from && p.ptype == r.ptype && p.ip.Equal(r.ip) {
|
||||
ok, requestDone := p.callback(r.data)
|
||||
matched = matched || ok
|
||||
// Remove the matcher if callback indicates that all replies have been received.
|
||||
if requestDone {
|
||||
p.errc <- nil
|
||||
plist.Remove(el)
|
||||
}
|
||||
// Reset the continuous timeout counter (time drift detection)
|
||||
contTimeouts = 0
|
||||
}
|
||||
}
|
||||
r.matched <- matched
|
||||
|
||||
case now := <-timeout.C:
|
||||
nextTimeout = nil
|
||||
|
||||
// Notify and remove callbacks whose deadline is in the past.
|
||||
for el := plist.Front(); el != nil; el = el.Next() {
|
||||
p := el.Value.(*replyMatcher)
|
||||
if now.After(p.deadline) || now.Equal(p.deadline) {
|
||||
p.errc <- errTimeout
|
||||
plist.Remove(el)
|
||||
contTimeouts++
|
||||
}
|
||||
}
|
||||
// If we've accumulated too many timeouts, do an NTP time sync check
|
||||
if contTimeouts > ntpFailureThreshold {
|
||||
if time.Since(ntpWarnTime) >= ntpWarningCooldown {
|
||||
ntpWarnTime = time.Now()
|
||||
go checkClockDrift()
|
||||
}
|
||||
contTimeouts = 0
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
const (
|
||||
macSize = 256 / 8
|
||||
sigSize = 520 / 8
|
||||
headSize = macSize + sigSize // space of packet frame data
|
||||
)
|
||||
|
||||
var (
|
||||
headSpace = make([]byte, headSize)
|
||||
|
||||
// Neighbors replies are sent across multiple packets to
|
||||
// stay below the packet size limit. We compute the maximum number
|
||||
// of entries by stuffing a packet until it grows too large.
|
||||
maxNeighbors int
|
||||
)
|
||||
|
||||
func init() {
|
||||
p := neighborsV4{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 >= maxPacketSize {
|
||||
maxNeighbors = n
|
||||
break
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func (t *UDPv4) send(toaddr *net.UDPAddr, toid enode.ID, ptype byte, req packetV4) ([]byte, error) {
|
||||
packet, hash, err := t.encode(t.priv, ptype, req)
|
||||
if err != nil {
|
||||
return hash, err
|
||||
}
|
||||
return hash, t.write(toaddr, toid, req.name(), packet)
|
||||
}
|
||||
|
||||
func (t *UDPv4) write(toaddr *net.UDPAddr, toid enode.ID, what string, packet []byte) error {
|
||||
_, err := t.conn.WriteToUDP(packet, toaddr)
|
||||
t.log.Trace(">> "+what, "id", toid, "addr", toaddr, "err", err)
|
||||
return err
|
||||
}
|
||||
|
||||
func (t *UDPv4) encode(priv *ecdsa.PrivateKey, ptype byte, req interface{}) (packet, hash []byte, err error) {
|
||||
b := new(bytes.Buffer)
|
||||
b.Write(headSpace)
|
||||
b.WriteByte(ptype)
|
||||
if err := rlp.Encode(b, req); err != nil {
|
||||
t.log.Error("Can't encode discv4 packet", "err", err)
|
||||
return nil, nil, err
|
||||
}
|
||||
packet = b.Bytes()
|
||||
sig, err := crypto.Sign(crypto.Keccak256(packet[headSize:]), priv)
|
||||
if err != nil {
|
||||
t.log.Error("Can't sign discv4 packet", "err", 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. Our public key will be part of this hash in
|
||||
// The future.
|
||||
hash = crypto.Keccak256(packet[macSize:])
|
||||
copy(packet, hash)
|
||||
return packet, hash, nil
|
||||
}
|
||||
|
||||
// readLoop runs in its own goroutine. it handles incoming UDP packets.
|
||||
func (t *UDPv4) readLoop(unhandled chan<- ReadPacket) {
|
||||
defer t.wg.Done()
|
||||
if unhandled != nil {
|
||||
defer close(unhandled)
|
||||
}
|
||||
|
||||
buf := make([]byte, maxPacketSize)
|
||||
for {
|
||||
nbytes, from, err := t.conn.ReadFromUDP(buf)
|
||||
if netutil.IsTemporaryError(err) {
|
||||
// Ignore temporary read errors.
|
||||
t.log.Debug("Temporary UDP read error", "err", err)
|
||||
continue
|
||||
} else if err != nil {
|
||||
// Shut down the loop for permament errors.
|
||||
if err != io.EOF {
|
||||
t.log.Debug("UDP read error", "err", err)
|
||||
}
|
||||
return
|
||||
}
|
||||
if t.handlePacket(from, buf[:nbytes]) != nil && unhandled != nil {
|
||||
select {
|
||||
case unhandled <- ReadPacket{buf[:nbytes], from}:
|
||||
default:
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func (t *UDPv4) handlePacket(from *net.UDPAddr, buf []byte) error {
|
||||
packet, fromKey, hash, err := decodeV4(buf)
|
||||
if err != nil {
|
||||
t.log.Debug("Bad discv4 packet", "addr", from, "err", err)
|
||||
return err
|
||||
}
|
||||
fromID := fromKey.id()
|
||||
if err == nil {
|
||||
err = packet.preverify(t, from, fromID, fromKey)
|
||||
}
|
||||
t.log.Trace("<< "+packet.name(), "id", fromID, "addr", from, "err", err)
|
||||
if err == nil {
|
||||
packet.handle(t, from, fromID, hash)
|
||||
}
|
||||
return err
|
||||
}
|
||||
|
||||
func decodeV4(buf []byte) (packetV4, encPubkey, []byte, error) {
|
||||
if len(buf) < headSize+1 {
|
||||
return nil, encPubkey{}, nil, errPacketTooSmall
|
||||
}
|
||||
hash, sig, sigdata := buf[:macSize], buf[macSize:headSize], buf[headSize:]
|
||||
shouldhash := crypto.Keccak256(buf[macSize:])
|
||||
if !bytes.Equal(hash, shouldhash) {
|
||||
return nil, encPubkey{}, nil, errBadHash
|
||||
}
|
||||
fromKey, err := recoverNodeKey(crypto.Keccak256(buf[headSize:]), sig)
|
||||
if err != nil {
|
||||
return nil, fromKey, hash, err
|
||||
}
|
||||
|
||||
var req packetV4
|
||||
switch ptype := sigdata[0]; ptype {
|
||||
case p_pingV4:
|
||||
req = new(pingV4)
|
||||
case p_pongV4:
|
||||
req = new(pongV4)
|
||||
case p_findnodeV4:
|
||||
req = new(findnodeV4)
|
||||
case p_neighborsV4:
|
||||
req = new(neighborsV4)
|
||||
default:
|
||||
return nil, fromKey, hash, fmt.Errorf("unknown type: %d", ptype)
|
||||
}
|
||||
s := rlp.NewStream(bytes.NewReader(sigdata[1:]), 0)
|
||||
err = s.Decode(req)
|
||||
return req, fromKey, hash, err
|
||||
}
|
||||
|
||||
// Packet Handlers
|
||||
|
||||
func (req *pingV4) preverify(t *UDPv4, from *net.UDPAddr, fromID enode.ID, fromKey encPubkey) error {
|
||||
if expired(req.Expiration) {
|
||||
return errExpired
|
||||
}
|
||||
key, err := decodePubkey(fromKey)
|
||||
if err != nil {
|
||||
return errors.New("invalid public key")
|
||||
}
|
||||
req.senderKey = key
|
||||
return nil
|
||||
}
|
||||
|
||||
func (req *pingV4) handle(t *UDPv4, from *net.UDPAddr, fromID enode.ID, mac []byte) {
|
||||
// Reply.
|
||||
t.send(from, fromID, p_pongV4, &pongV4{
|
||||
To: makeEndpoint(from, req.From.TCP),
|
||||
ReplyTok: mac,
|
||||
Expiration: uint64(time.Now().Add(expiration).Unix()),
|
||||
})
|
||||
|
||||
// Ping back if our last pong on file is too far in the past.
|
||||
n := wrapNode(enode.NewV4(req.senderKey, from.IP, int(req.From.TCP), from.Port))
|
||||
if time.Since(t.db.LastPongReceived(n.ID(), from.IP)) > bondExpiration {
|
||||
t.sendPing(fromID, from, func() {
|
||||
t.tab.addVerifiedNode(n)
|
||||
})
|
||||
} else {
|
||||
t.tab.addVerifiedNode(n)
|
||||
}
|
||||
|
||||
// Update node database and endpoint predictor.
|
||||
t.db.UpdateLastPingReceived(n.ID(), from.IP, time.Now())
|
||||
t.localNode.UDPEndpointStatement(from, &net.UDPAddr{IP: req.To.IP, Port: int(req.To.UDP)})
|
||||
}
|
||||
|
||||
func (req *pingV4) name() string { return "PING/v4" }
|
||||
|
||||
func (req *pongV4) preverify(t *UDPv4, from *net.UDPAddr, fromID enode.ID, fromKey encPubkey) error {
|
||||
if expired(req.Expiration) {
|
||||
return errExpired
|
||||
}
|
||||
if !t.handleReply(fromID, from.IP, p_pongV4, req) {
|
||||
return errUnsolicitedReply
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func (req *pongV4) handle(t *UDPv4, from *net.UDPAddr, fromID enode.ID, mac []byte) {
|
||||
t.localNode.UDPEndpointStatement(from, &net.UDPAddr{IP: req.To.IP, Port: int(req.To.UDP)})
|
||||
t.db.UpdateLastPongReceived(fromID, from.IP, time.Now())
|
||||
}
|
||||
|
||||
func (req *pongV4) name() string { return "PONG/v4" }
|
||||
|
||||
func (req *findnodeV4) preverify(t *UDPv4, from *net.UDPAddr, fromID enode.ID, fromKey encPubkey) error {
|
||||
if expired(req.Expiration) {
|
||||
return errExpired
|
||||
}
|
||||
if time.Since(t.db.LastPongReceived(fromID, from.IP)) > bondExpiration {
|
||||
// No endpoint proof pong 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
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func (req *findnodeV4) handle(t *UDPv4, from *net.UDPAddr, fromID enode.ID, mac []byte) {
|
||||
// Determine closest nodes.
|
||||
target := enode.ID(crypto.Keccak256Hash(req.Target[:]))
|
||||
t.tab.mutex.Lock()
|
||||
closest := t.tab.closest(target, bucketSize, true).entries
|
||||
t.tab.mutex.Unlock()
|
||||
|
||||
// Send neighbors in chunks with at most maxNeighbors per packet
|
||||
// to stay below the packet size limit.
|
||||
p := neighborsV4{Expiration: uint64(time.Now().Add(expiration).Unix())}
|
||||
var sent bool
|
||||
for _, n := range closest {
|
||||
if netutil.CheckRelayIP(from.IP, n.IP()) == nil {
|
||||
p.Nodes = append(p.Nodes, nodeToRPC(n))
|
||||
}
|
||||
if len(p.Nodes) == maxNeighbors {
|
||||
t.send(from, fromID, p_neighborsV4, &p)
|
||||
p.Nodes = p.Nodes[:0]
|
||||
sent = true
|
||||
}
|
||||
}
|
||||
if len(p.Nodes) > 0 || !sent {
|
||||
t.send(from, fromID, p_neighborsV4, &p)
|
||||
}
|
||||
}
|
||||
|
||||
func (req *findnodeV4) name() string { return "FINDNODE/v4" }
|
||||
|
||||
func (req *neighborsV4) preverify(t *UDPv4, from *net.UDPAddr, fromID enode.ID, fromKey encPubkey) error {
|
||||
if expired(req.Expiration) {
|
||||
return errExpired
|
||||
}
|
||||
if !t.handleReply(fromID, from.IP, p_neighborsV4, req) {
|
||||
return errUnsolicitedReply
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func (req *neighborsV4) handle(t *UDPv4, from *net.UDPAddr, fromID enode.ID, mac []byte) {
|
||||
}
|
||||
|
||||
func (req *neighborsV4) name() string { return "NEIGHBORS/v4" }
|
||||
|
||||
func expired(ts uint64) bool {
|
||||
return time.Unix(int64(ts), 0).Before(time.Now())
|
||||
}
|
||||
Reference in New Issue
Block a user