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702 lines
20 KiB
702 lines
20 KiB
package pex
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import (
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"fmt"
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"reflect"
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"sort"
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"sync"
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"time"
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amino "github.com/tendermint/go-amino"
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cmn "github.com/tendermint/tmlibs/common"
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"github.com/tendermint/tendermint/p2p"
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"github.com/tendermint/tendermint/p2p/conn"
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)
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type Peer = p2p.Peer
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const (
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// PexChannel is a channel for PEX messages
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PexChannel = byte(0x00)
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// over-estimate of max NetAddress size
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// hexID (40) + IP (16) + Port (2) + Name (100) ...
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// NOTE: dont use massive DNS name ..
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maxAddressSize = 256
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// NOTE: amplificaiton factor!
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// small request results in up to maxMsgSize response
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maxMsgSize = maxAddressSize * maxGetSelection
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// ensure we have enough peers
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defaultEnsurePeersPeriod = 30 * time.Second
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defaultMinNumOutboundPeers = p2p.DefaultMinNumOutboundPeers
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// Seed/Crawler constants
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// We want seeds to only advertise good peers. Therefore they should wait at
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// least as long as we expect it to take for a peer to become good before
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// disconnecting.
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// see consensus/reactor.go: blocksToContributeToBecomeGoodPeer
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// 10000 blocks assuming 1s blocks ~ 2.7 hours.
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defaultSeedDisconnectWaitPeriod = 3 * time.Hour
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defaultCrawlPeerInterval = 2 * time.Minute // don't redial for this. TODO: back-off. what for?
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defaultCrawlPeersPeriod = 30 * time.Second // check some peers every this
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maxAttemptsToDial = 16 // ~ 35h in total (last attempt - 18h)
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// if node connects to seed, it does not have any trusted peers.
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// Especially in the beginning, node should have more trusted peers than
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// untrusted.
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biasToSelectNewPeers = 30 // 70 to select good peers
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)
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// PEXReactor handles PEX (peer exchange) and ensures that an
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// adequate number of peers are connected to the switch.
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//
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// It uses `AddrBook` (address book) to store `NetAddress`es of the peers.
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//
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// ## Preventing abuse
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//
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// Only accept pexAddrsMsg from peers we sent a corresponding pexRequestMsg too.
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// Only accept one pexRequestMsg every ~defaultEnsurePeersPeriod.
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type PEXReactor struct {
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p2p.BaseReactor
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book AddrBook
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config *PEXReactorConfig
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ensurePeersPeriod time.Duration // TODO: should go in the config
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// maps to prevent abuse
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requestsSent *cmn.CMap // ID->struct{}: unanswered send requests
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lastReceivedRequests *cmn.CMap // ID->time.Time: last time peer requested from us
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attemptsToDial sync.Map // address (string) -> {number of attempts (int), last time dialed (time.Time)}
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}
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func (r *PEXReactor) minReceiveRequestInterval() time.Duration {
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// NOTE: must be less than ensurePeersPeriod, otherwise we'll request
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// peers too quickly from others and they'll think we're bad!
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return r.ensurePeersPeriod / 3
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}
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// PEXReactorConfig holds reactor specific configuration data.
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type PEXReactorConfig struct {
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// Seed/Crawler mode
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SeedMode bool
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// Seeds is a list of addresses reactor may use
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// if it can't connect to peers in the addrbook.
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Seeds []string
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// PrivatePeerIDs is a list of peer IDs, which must not be gossiped to other
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// peers.
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PrivatePeerIDs []string
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}
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type _attemptsToDial struct {
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number int
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lastDialed time.Time
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}
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// NewPEXReactor creates new PEX reactor.
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func NewPEXReactor(b AddrBook, config *PEXReactorConfig) *PEXReactor {
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r := &PEXReactor{
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book: b,
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config: config,
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ensurePeersPeriod: defaultEnsurePeersPeriod,
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requestsSent: cmn.NewCMap(),
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lastReceivedRequests: cmn.NewCMap(),
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}
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r.BaseReactor = *p2p.NewBaseReactor("PEXReactor", r)
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return r
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}
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// OnStart implements BaseService
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func (r *PEXReactor) OnStart() error {
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if err := r.BaseReactor.OnStart(); err != nil {
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return err
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}
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err := r.book.Start()
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if err != nil && err != cmn.ErrAlreadyStarted {
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return err
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}
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// return err if user provided a bad seed address
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// or a host name that we cant resolve
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if err := r.checkSeeds(); err != nil {
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return err
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}
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// Check if this node should run
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// in seed/crawler mode
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if r.config.SeedMode {
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go r.crawlPeersRoutine()
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} else {
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go r.ensurePeersRoutine()
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}
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return nil
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}
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// OnStop implements BaseService
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func (r *PEXReactor) OnStop() {
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r.BaseReactor.OnStop()
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r.book.Stop()
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}
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// GetChannels implements Reactor
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func (r *PEXReactor) GetChannels() []*conn.ChannelDescriptor {
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return []*conn.ChannelDescriptor{
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{
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ID: PexChannel,
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Priority: 1,
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SendQueueCapacity: 10,
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},
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}
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}
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// AddPeer implements Reactor by adding peer to the address book (if inbound)
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// or by requesting more addresses (if outbound).
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func (r *PEXReactor) AddPeer(p Peer) {
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if p.IsOutbound() {
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// For outbound peers, the address is already in the books -
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// either via DialPeersAsync or r.Receive.
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// Ask it for more peers if we need.
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if r.book.NeedMoreAddrs() {
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r.RequestAddrs(p)
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}
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} else {
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// inbound peer is its own source
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addr := p.NodeInfo().NetAddress()
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src := addr
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// ignore private addrs
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if isAddrPrivate(addr, r.config.PrivatePeerIDs) {
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return
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}
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// add to book. dont RequestAddrs right away because
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// we don't trust inbound as much - let ensurePeersRoutine handle it.
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err := r.book.AddAddress(addr, src)
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r.logErrAddrBook(err)
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}
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}
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func (r *PEXReactor) logErrAddrBook(err error) {
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if err != nil {
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switch err.(type) {
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case ErrAddrBookNilAddr:
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r.Logger.Error("Failed to add new address", "err", err)
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default:
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// non-routable, self, full book, etc.
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r.Logger.Debug("Failed to add new address", "err", err)
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}
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}
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}
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// RemovePeer implements Reactor.
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func (r *PEXReactor) RemovePeer(p Peer, reason interface{}) {
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id := string(p.ID())
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r.requestsSent.Delete(id)
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r.lastReceivedRequests.Delete(id)
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}
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// Receive implements Reactor by handling incoming PEX messages.
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func (r *PEXReactor) Receive(chID byte, src Peer, msgBytes []byte) {
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msg, err := DecodeMessage(msgBytes)
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if err != nil {
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r.Logger.Error("Error decoding message", "src", src, "chId", chID, "msg", msg, "err", err, "bytes", msgBytes)
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r.Switch.StopPeerForError(src, err)
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return
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}
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r.Logger.Debug("Received message", "src", src, "chId", chID, "msg", msg)
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switch msg := msg.(type) {
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case *pexRequestMessage:
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// Check we're not receiving too many requests
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if err := r.receiveRequest(src); err != nil {
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r.Switch.StopPeerForError(src, err)
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return
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}
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// Seeds disconnect after sending a batch of addrs
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// NOTE: this is a prime candidate for amplification attacks
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// so it's important we
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// 1) restrict how frequently peers can request
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// 2) limit the output size
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if r.config.SeedMode {
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r.SendAddrs(src, r.book.GetSelectionWithBias(biasToSelectNewPeers))
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r.Switch.StopPeerGracefully(src)
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} else {
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r.SendAddrs(src, r.book.GetSelection())
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}
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case *pexAddrsMessage:
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// If we asked for addresses, add them to the book
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if err := r.ReceiveAddrs(msg.Addrs, src); err != nil {
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r.Switch.StopPeerForError(src, err)
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return
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}
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default:
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r.Logger.Error(fmt.Sprintf("Unknown message type %v", reflect.TypeOf(msg)))
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}
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}
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// enforces a minimum amount of time between requests
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func (r *PEXReactor) receiveRequest(src Peer) error {
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id := string(src.ID())
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v := r.lastReceivedRequests.Get(id)
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if v == nil {
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// initialize with empty time
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lastReceived := time.Time{}
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r.lastReceivedRequests.Set(id, lastReceived)
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return nil
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}
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lastReceived := v.(time.Time)
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if lastReceived.Equal(time.Time{}) {
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// first time gets a free pass. then we start tracking the time
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lastReceived = time.Now()
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r.lastReceivedRequests.Set(id, lastReceived)
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return nil
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}
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now := time.Now()
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minInterval := r.minReceiveRequestInterval()
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if now.Sub(lastReceived) < minInterval {
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return fmt.Errorf("Peer (%v) sent next PEX request too soon. lastReceived: %v, now: %v, minInterval: %v. Disconnecting",
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src.ID(),
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lastReceived,
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now,
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minInterval,
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)
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}
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r.lastReceivedRequests.Set(id, now)
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return nil
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}
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// RequestAddrs asks peer for more addresses if we do not already
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// have a request out for this peer.
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func (r *PEXReactor) RequestAddrs(p Peer) {
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r.Logger.Debug("Request addrs", "from", p)
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id := string(p.ID())
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if r.requestsSent.Has(id) {
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return
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}
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r.requestsSent.Set(id, struct{}{})
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p.Send(PexChannel, cdc.MustMarshalBinary(&pexRequestMessage{}))
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}
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// ReceiveAddrs adds the given addrs to the addrbook if theres an open
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// request for this peer and deletes the open request.
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// If there's no open request for the src peer, it returns an error.
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func (r *PEXReactor) ReceiveAddrs(addrs []*p2p.NetAddress, src Peer) error {
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id := string(src.ID())
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if !r.requestsSent.Has(id) {
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return cmn.NewError("Received unsolicited pexAddrsMessage")
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}
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r.requestsSent.Delete(id)
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srcAddr := src.NodeInfo().NetAddress()
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for _, netAddr := range addrs {
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// NOTE: GetSelection methods should never return nil addrs
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if netAddr == nil {
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return cmn.NewError("received nil addr")
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}
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// ignore private peers
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// TODO: give private peers to AddrBook so it can enforce this on AddAddress.
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// We'd then have to check for ErrPrivatePeer on AddAddress here, which is
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// an error we just ignore (maybe peer is probing us for our private peers :P)
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if isAddrPrivate(netAddr, r.config.PrivatePeerIDs) {
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continue
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}
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err := r.book.AddAddress(netAddr, srcAddr)
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r.logErrAddrBook(err)
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}
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return nil
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}
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// SendAddrs sends addrs to the peer.
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func (r *PEXReactor) SendAddrs(p Peer, netAddrs []*p2p.NetAddress) {
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p.Send(PexChannel, cdc.MustMarshalBinary(&pexAddrsMessage{Addrs: netAddrs}))
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}
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// SetEnsurePeersPeriod sets period to ensure peers connected.
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func (r *PEXReactor) SetEnsurePeersPeriod(d time.Duration) {
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r.ensurePeersPeriod = d
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}
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// Ensures that sufficient peers are connected. (continuous)
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func (r *PEXReactor) ensurePeersRoutine() {
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var (
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seed = cmn.NewRand()
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jitter = seed.Int63n(r.ensurePeersPeriod.Nanoseconds())
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)
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// Randomize first round of communication to avoid thundering herd.
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// If no potential peers are present directly start connecting so we guarantee
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// swift setup with the help of configured seeds.
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if r.hasPotentialPeers() {
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time.Sleep(time.Duration(jitter))
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}
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// fire once immediately.
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// ensures we dial the seeds right away if the book is empty
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r.ensurePeers()
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// fire periodically
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ticker := time.NewTicker(r.ensurePeersPeriod)
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for {
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select {
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case <-ticker.C:
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r.ensurePeers()
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case <-r.Quit():
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ticker.Stop()
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return
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}
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}
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}
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// ensurePeers ensures that sufficient peers are connected. (once)
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//
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// heuristic that we haven't perfected yet, or, perhaps is manually edited by
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// the node operator. It should not be used to compute what addresses are
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// already connected or not.
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func (r *PEXReactor) ensurePeers() {
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var (
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out, in, dial = r.Switch.NumPeers()
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numToDial = defaultMinNumOutboundPeers - (out + dial)
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)
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r.Logger.Info(
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"Ensure peers",
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"numOutPeers", out,
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"numInPeers", in,
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"numDialing", dial,
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"numToDial", numToDial,
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)
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if numToDial <= 0 {
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return
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}
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// bias to prefer more vetted peers when we have fewer connections.
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// not perfect, but somewhate ensures that we prioritize connecting to more-vetted
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// NOTE: range here is [10, 90]. Too high ?
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newBias := cmn.MinInt(out, 8)*10 + 10
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toDial := make(map[p2p.ID]*p2p.NetAddress)
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// Try maxAttempts times to pick numToDial addresses to dial
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maxAttempts := numToDial * 3
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for i := 0; i < maxAttempts && len(toDial) < numToDial; i++ {
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try := r.book.PickAddress(newBias)
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if try == nil {
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continue
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}
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if _, selected := toDial[try.ID]; selected {
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continue
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}
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if dialling := r.Switch.IsDialing(try.ID); dialling {
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continue
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}
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if connected := r.Switch.Peers().Has(try.ID); connected {
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continue
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}
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// TODO: consider moving some checks from toDial into here
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// so we don't even consider dialing peers that we want to wait
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// before dialling again, or have dialed too many times already
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r.Logger.Info("Will dial address", "addr", try)
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toDial[try.ID] = try
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}
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// Dial picked addresses
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for _, addr := range toDial {
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go r.dialPeer(addr)
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}
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// If we need more addresses, pick a random peer and ask for more.
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if r.book.NeedMoreAddrs() {
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peers := r.Switch.Peers().List()
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peersCount := len(peers)
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if peersCount > 0 {
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peer := peers[cmn.RandInt()%peersCount] // nolint: gas
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r.Logger.Info("We need more addresses. Sending pexRequest to random peer", "peer", peer)
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r.RequestAddrs(peer)
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}
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}
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// If we are not connected to nor dialing anybody, fallback to dialing a seed.
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if out+in+dial+len(toDial) == 0 {
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r.Logger.Info("No addresses to dial nor connected peers. Falling back to seeds")
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r.dialSeeds()
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}
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}
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func (r *PEXReactor) dialAttemptsInfo(addr *p2p.NetAddress) (attempts int, lastDialed time.Time) {
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_attempts, ok := r.attemptsToDial.Load(addr.DialString())
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if !ok {
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return
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}
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atd := _attempts.(_attemptsToDial)
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return atd.number, atd.lastDialed
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}
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func (r *PEXReactor) dialPeer(addr *p2p.NetAddress) {
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attempts, lastDialed := r.dialAttemptsInfo(addr)
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if attempts > maxAttemptsToDial {
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r.Logger.Error("Reached max attempts to dial", "addr", addr, "attempts", attempts)
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r.book.MarkBad(addr)
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return
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}
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// exponential backoff if it's not our first attempt to dial given address
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if attempts > 0 {
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jitterSeconds := time.Duration(cmn.RandFloat64() * float64(time.Second)) // 1s == (1e9 ns)
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backoffDuration := jitterSeconds + ((1 << uint(attempts)) * time.Second)
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sinceLastDialed := time.Since(lastDialed)
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if sinceLastDialed < backoffDuration {
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r.Logger.Debug("Too early to dial", "addr", addr, "backoff_duration", backoffDuration, "last_dialed", lastDialed, "time_since", sinceLastDialed)
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return
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}
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}
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err := r.Switch.DialPeerWithAddress(addr, false)
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if err != nil {
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r.Logger.Error("Dialing failed", "addr", addr, "err", err, "attempts", attempts)
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// TODO: detect more "bad peer" scenarios
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if _, ok := err.(p2p.ErrSwitchAuthenticationFailure); ok {
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r.book.MarkBad(addr)
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r.attemptsToDial.Delete(addr.DialString())
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} else {
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r.book.MarkAttempt(addr)
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// FIXME: if the addr is going to be removed from the addrbook (hard to
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// tell at this point), we need to Delete it from attemptsToDial, not
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// record another attempt.
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// record attempt
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r.attemptsToDial.Store(addr.DialString(), _attemptsToDial{attempts + 1, time.Now()})
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}
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} else {
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// cleanup any history
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r.attemptsToDial.Delete(addr.DialString())
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}
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}
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// check seed addresses are well formed
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func (r *PEXReactor) checkSeeds() error {
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lSeeds := len(r.config.Seeds)
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if lSeeds == 0 {
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return nil
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}
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_, errs := p2p.NewNetAddressStrings(r.config.Seeds)
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for _, err := range errs {
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if err != nil {
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return err
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}
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}
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return nil
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}
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// randomly dial seeds until we connect to one or exhaust them
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func (r *PEXReactor) dialSeeds() {
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lSeeds := len(r.config.Seeds)
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if lSeeds == 0 {
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return
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}
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|
seedAddrs, _ := p2p.NewNetAddressStrings(r.config.Seeds)
|
|
|
|
perm := cmn.RandPerm(lSeeds)
|
|
// perm := r.Switch.rng.Perm(lSeeds)
|
|
for _, i := range perm {
|
|
// dial a random seed
|
|
seedAddr := seedAddrs[i]
|
|
err := r.Switch.DialPeerWithAddress(seedAddr, false)
|
|
if err == nil {
|
|
return
|
|
}
|
|
r.Switch.Logger.Error("Error dialing seed", "err", err, "seed", seedAddr)
|
|
}
|
|
r.Switch.Logger.Error("Couldn't connect to any seeds")
|
|
}
|
|
|
|
// AttemptsToDial returns the number of attempts to dial specific address. It
|
|
// returns 0 if never attempted or successfully connected.
|
|
func (r *PEXReactor) AttemptsToDial(addr *p2p.NetAddress) int {
|
|
lAttempts, attempted := r.attemptsToDial.Load(addr.DialString())
|
|
if attempted {
|
|
return lAttempts.(_attemptsToDial).number
|
|
}
|
|
return 0
|
|
}
|
|
|
|
//----------------------------------------------------------
|
|
|
|
// Explores the network searching for more peers. (continuous)
|
|
// Seed/Crawler Mode causes this node to quickly disconnect
|
|
// from peers, except other seed nodes.
|
|
func (r *PEXReactor) crawlPeersRoutine() {
|
|
// Do an initial crawl
|
|
r.crawlPeers()
|
|
|
|
// Fire periodically
|
|
ticker := time.NewTicker(defaultCrawlPeersPeriod)
|
|
|
|
for {
|
|
select {
|
|
case <-ticker.C:
|
|
r.attemptDisconnects()
|
|
r.crawlPeers()
|
|
case <-r.Quit():
|
|
return
|
|
}
|
|
}
|
|
}
|
|
|
|
// hasPotentialPeers indicates if there is a potential peer to connect to, by
|
|
// consulting the Switch as well as the AddrBook.
|
|
func (r *PEXReactor) hasPotentialPeers() bool {
|
|
out, in, dial := r.Switch.NumPeers()
|
|
|
|
return out+in+dial > 0 && len(r.book.ListOfKnownAddresses()) > 0
|
|
}
|
|
|
|
// crawlPeerInfo handles temporary data needed for the
|
|
// network crawling performed during seed/crawler mode.
|
|
type crawlPeerInfo struct {
|
|
// The listening address of a potential peer we learned about
|
|
Addr *p2p.NetAddress
|
|
|
|
// The last time we attempt to reach this address
|
|
LastAttempt time.Time
|
|
|
|
// The last time we successfully reached this address
|
|
LastSuccess time.Time
|
|
}
|
|
|
|
// oldestFirst implements sort.Interface for []crawlPeerInfo
|
|
// based on the LastAttempt field.
|
|
type oldestFirst []crawlPeerInfo
|
|
|
|
func (of oldestFirst) Len() int { return len(of) }
|
|
func (of oldestFirst) Swap(i, j int) { of[i], of[j] = of[j], of[i] }
|
|
func (of oldestFirst) Less(i, j int) bool { return of[i].LastAttempt.Before(of[j].LastAttempt) }
|
|
|
|
// getPeersToCrawl returns addresses of potential peers that we wish to validate.
|
|
// NOTE: The status information is ordered as described above.
|
|
func (r *PEXReactor) getPeersToCrawl() []crawlPeerInfo {
|
|
var of oldestFirst
|
|
|
|
// TODO: be more selective
|
|
addrs := r.book.ListOfKnownAddresses()
|
|
for _, addr := range addrs {
|
|
if len(addr.ID()) == 0 {
|
|
continue // dont use peers without id
|
|
}
|
|
|
|
of = append(of, crawlPeerInfo{
|
|
Addr: addr.Addr,
|
|
LastAttempt: addr.LastAttempt,
|
|
LastSuccess: addr.LastSuccess,
|
|
})
|
|
}
|
|
sort.Sort(of)
|
|
return of
|
|
}
|
|
|
|
// crawlPeers will crawl the network looking for new peer addresses. (once)
|
|
func (r *PEXReactor) crawlPeers() {
|
|
peerInfos := r.getPeersToCrawl()
|
|
|
|
now := time.Now()
|
|
// Use addresses we know of to reach additional peers
|
|
for _, pi := range peerInfos {
|
|
// Do not attempt to connect with peers we recently dialed
|
|
if now.Sub(pi.LastAttempt) < defaultCrawlPeerInterval {
|
|
continue
|
|
}
|
|
// Otherwise, attempt to connect with the known address
|
|
err := r.Switch.DialPeerWithAddress(pi.Addr, false)
|
|
if err != nil {
|
|
r.book.MarkAttempt(pi.Addr)
|
|
continue
|
|
}
|
|
// Ask for more addresses
|
|
peer := r.Switch.Peers().Get(pi.Addr.ID)
|
|
if peer != nil {
|
|
r.RequestAddrs(peer)
|
|
}
|
|
}
|
|
}
|
|
|
|
// attemptDisconnects checks if we've been with each peer long enough to disconnect
|
|
func (r *PEXReactor) attemptDisconnects() {
|
|
for _, peer := range r.Switch.Peers().List() {
|
|
if peer.Status().Duration < defaultSeedDisconnectWaitPeriod {
|
|
continue
|
|
}
|
|
if peer.IsPersistent() {
|
|
continue
|
|
}
|
|
r.Switch.StopPeerGracefully(peer)
|
|
}
|
|
}
|
|
|
|
// isAddrPrivate returns true if addr.ID is a private ID.
|
|
func isAddrPrivate(addr *p2p.NetAddress, privatePeerIDs []string) bool {
|
|
for _, id := range privatePeerIDs {
|
|
if string(addr.ID) == id {
|
|
return true
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
//-----------------------------------------------------------------------------
|
|
// Messages
|
|
|
|
// PexMessage is a primary type for PEX messages. Underneath, it could contain
|
|
// either pexRequestMessage, or pexAddrsMessage messages.
|
|
type PexMessage interface{}
|
|
|
|
func RegisterPexMessage(cdc *amino.Codec) {
|
|
cdc.RegisterInterface((*PexMessage)(nil), nil)
|
|
cdc.RegisterConcrete(&pexRequestMessage{}, "tendermint/p2p/PexRequestMessage", nil)
|
|
cdc.RegisterConcrete(&pexAddrsMessage{}, "tendermint/p2p/PexAddrsMessage", nil)
|
|
}
|
|
|
|
// DecodeMessage implements interface registered above.
|
|
func DecodeMessage(bz []byte) (msg PexMessage, err error) {
|
|
if len(bz) > maxMsgSize {
|
|
return msg, fmt.Errorf("Msg exceeds max size (%d > %d)",
|
|
len(bz), maxMsgSize)
|
|
}
|
|
err = cdc.UnmarshalBinary(bz, &msg)
|
|
return
|
|
}
|
|
|
|
/*
|
|
A pexRequestMessage requests additional peer addresses.
|
|
*/
|
|
type pexRequestMessage struct {
|
|
}
|
|
|
|
func (m *pexRequestMessage) String() string {
|
|
return "[pexRequest]"
|
|
}
|
|
|
|
/*
|
|
A message with announced peer addresses.
|
|
*/
|
|
type pexAddrsMessage struct {
|
|
Addrs []*p2p.NetAddress
|
|
}
|
|
|
|
func (m *pexAddrsMessage) String() string {
|
|
return fmt.Sprintf("[pexAddrs %v]", m.Addrs)
|
|
}
|