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server.go
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server.go
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package p2p
import (
"bytes"
"errors"
"fmt"
"net"
"sync"
"time"
"github.com/ethereum/go-ethereum/logger"
)
const (
outboundAddressPoolSize = 500
defaultDialTimeout = 10 * time.Second
portMappingUpdateInterval = 15 * time.Minute
portMappingTimeout = 20 * time.Minute
)
var srvlog = logger.NewLogger("P2P Server")
// Server manages all peer connections.
//
// The fields of Server are used as configuration parameters.
// You should set them before starting the Server. Fields may not be
// modified while the server is running.
type Server struct {
// This field must be set to a valid client identity.
Identity ClientIdentity
// MaxPeers is the maximum number of peers that can be
// connected. It must be greater than zero.
MaxPeers int
// Protocols should contain the protocols supported
// by the server. Matching protocols are launched for
// each peer.
Protocols []Protocol
// If Blacklist is set to a non-nil value, the given Blacklist
// is used to verify peer connections.
Blacklist Blacklist
// If ListenAddr is set to a non-nil address, the server
// will listen for incoming connections.
//
// If the port is zero, the operating system will pick a port. The
// ListenAddr field will be updated with the actual address when
// the server is started.
ListenAddr string
// If set to a non-nil value, the given NAT port mapper
// is used to make the listening port available to the
// Internet.
NAT NAT
// If Dialer is set to a non-nil value, the given Dialer
// is used to dial outbound peer connections.
Dialer *net.Dialer
// If NoDial is true, the server will not dial any peers.
NoDial bool
// Hook for testing. This is useful because we can inhibit
// the whole protocol stack.
newPeerFunc peerFunc
lock sync.RWMutex
running bool
listener net.Listener
laddr *net.TCPAddr // real listen addr
peers []*Peer
peerSlots chan int
peerCount int
quit chan struct{}
wg sync.WaitGroup
peerConnect chan *peerAddr
peerDisconnect chan *Peer
}
// NAT is implemented by NAT traversal methods.
type NAT interface {
GetExternalAddress() (net.IP, error)
AddPortMapping(protocol string, extport, intport int, name string, lifetime time.Duration) error
DeletePortMapping(protocol string, extport, intport int) error
// Should return name of the method.
String() string
}
type peerFunc func(srv *Server, c net.Conn, dialAddr *peerAddr) *Peer
// Peers returns all connected peers.
func (srv *Server) Peers() (peers []*Peer) {
srv.lock.RLock()
defer srv.lock.RUnlock()
for _, peer := range srv.peers {
if peer != nil {
peers = append(peers, peer)
}
}
return
}
// PeerCount returns the number of connected peers.
func (srv *Server) PeerCount() int {
srv.lock.RLock()
defer srv.lock.RUnlock()
return srv.peerCount
}
// SuggestPeer injects an address into the outbound address pool.
func (srv *Server) SuggestPeer(ip net.IP, port int, nodeID []byte) {
select {
case srv.peerConnect <- &peerAddr{ip, uint64(port), nodeID}:
default: // don't block
}
}
// Broadcast sends an RLP-encoded message to all connected peers.
// This method is deprecated and will be removed later.
func (srv *Server) Broadcast(protocol string, code uint64, data ...interface{}) {
var payload []byte
if data != nil {
payload = encodePayload(data...)
}
srv.lock.RLock()
defer srv.lock.RUnlock()
for _, peer := range srv.peers {
if peer != nil {
var msg = Msg{Code: code}
if data != nil {
msg.Payload = bytes.NewReader(payload)
msg.Size = uint32(len(payload))
}
peer.writeProtoMsg(protocol, msg)
}
}
}
// Start starts running the server.
// Servers can be re-used and started again after stopping.
func (srv *Server) Start() (err error) {
srv.lock.Lock()
defer srv.lock.Unlock()
if srv.running {
return errors.New("server already running")
}
srvlog.Infoln("Starting Server")
// initialize fields
if srv.Identity == nil {
return fmt.Errorf("Server.Identity must be set to a non-nil identity")
}
if srv.MaxPeers <= 0 {
return fmt.Errorf("Server.MaxPeers must be > 0")
}
srv.quit = make(chan struct{})
srv.peers = make([]*Peer, srv.MaxPeers)
srv.peerSlots = make(chan int, srv.MaxPeers)
srv.peerConnect = make(chan *peerAddr, outboundAddressPoolSize)
srv.peerDisconnect = make(chan *Peer)
if srv.newPeerFunc == nil {
srv.newPeerFunc = newServerPeer
}
if srv.Blacklist == nil {
srv.Blacklist = NewBlacklist()
}
if srv.Dialer == nil {
srv.Dialer = &net.Dialer{Timeout: defaultDialTimeout}
}
if srv.ListenAddr != "" {
if err := srv.startListening(); err != nil {
return err
}
}
if !srv.NoDial {
srv.wg.Add(1)
go srv.dialLoop()
}
if srv.NoDial && srv.ListenAddr == "" {
srvlog.Warnln("I will be kind-of useless, neither dialing nor listening.")
}
// make all slots available
for i := range srv.peers {
srv.peerSlots <- i
}
// note: discLoop is not part of WaitGroup
go srv.discLoop()
srv.running = true
return nil
}
func (srv *Server) startListening() error {
listener, err := net.Listen("tcp", srv.ListenAddr)
if err != nil {
return err
}
srv.ListenAddr = listener.Addr().String()
srv.laddr = listener.Addr().(*net.TCPAddr)
srv.listener = listener
srv.wg.Add(1)
go srv.listenLoop()
if !srv.laddr.IP.IsLoopback() && srv.NAT != nil {
srv.wg.Add(1)
go srv.natLoop(srv.laddr.Port)
}
return nil
}
// Stop terminates the server and all active peer connections.
// It blocks until all active connections have been closed.
func (srv *Server) Stop() {
srv.lock.Lock()
if !srv.running {
srv.lock.Unlock()
return
}
srv.running = false
srv.lock.Unlock()
srvlog.Infoln("Stopping server")
if srv.listener != nil {
// this unblocks listener Accept
srv.listener.Close()
}
close(srv.quit)
for _, peer := range srv.Peers() {
peer.Disconnect(DiscQuitting)
}
srv.wg.Wait()
// wait till they actually disconnect
// this is checked by claiming all peerSlots.
// slots become available as the peers disconnect.
for i := 0; i < cap(srv.peerSlots); i++ {
<-srv.peerSlots
}
// terminate discLoop
close(srv.peerDisconnect)
}
func (srv *Server) discLoop() {
for peer := range srv.peerDisconnect {
// peer has just disconnected. free up its slot.
srvlog.Infof("%v is gone", peer)
srv.peerSlots <- peer.slot
srv.lock.Lock()
srv.peers[peer.slot] = nil
srv.lock.Unlock()
}
}
// main loop for adding connections via listening
func (srv *Server) listenLoop() {
defer srv.wg.Done()
srvlog.Infoln("Listening on", srv.listener.Addr())
for {
select {
case slot := <-srv.peerSlots:
conn, err := srv.listener.Accept()
if err != nil {
srv.peerSlots <- slot
return
}
srvlog.Debugf("Accepted conn %v (slot %d)\n", conn.RemoteAddr(), slot)
srv.addPeer(conn, nil, slot)
case <-srv.quit:
return
}
}
}
func (srv *Server) natLoop(port int) {
defer srv.wg.Done()
for {
srv.updatePortMapping(port)
select {
case <-time.After(portMappingUpdateInterval):
// one more round
case <-srv.quit:
srv.removePortMapping(port)
return
}
}
}
func (srv *Server) updatePortMapping(port int) {
srvlog.Infoln("Attempting to map port", port, "with", srv.NAT)
err := srv.NAT.AddPortMapping("tcp", port, port, "ethereum p2p", portMappingTimeout)
if err != nil {
srvlog.Errorln("Port mapping error:", err)
return
}
extip, err := srv.NAT.GetExternalAddress()
if err != nil {
srvlog.Errorln("Error getting external IP:", err)
return
}
srv.lock.Lock()
extaddr := *(srv.listener.Addr().(*net.TCPAddr))
extaddr.IP = extip
srvlog.Infoln("Mapped port, external addr is", &extaddr)
srv.laddr = &extaddr
srv.lock.Unlock()
}
func (srv *Server) removePortMapping(port int) {
srvlog.Infoln("Removing port mapping for", port, "with", srv.NAT)
srv.NAT.DeletePortMapping("tcp", port, port)
}
func (srv *Server) dialLoop() {
defer srv.wg.Done()
var (
suggest chan *peerAddr
slot *int
slots = srv.peerSlots
)
for {
select {
case i := <-slots:
// we need a peer in slot i, slot reserved
slot = &i
// now we can watch for candidate peers in the next loop
suggest = srv.peerConnect
// do not consume more until candidate peer is found
slots = nil
case desc := <-suggest:
// candidate peer found, will dial out asyncronously
// if connection fails slot will be released
go srv.dialPeer(desc, *slot)
// we can watch if more peers needed in the next loop
slots = srv.peerSlots
// until then we dont care about candidate peers
suggest = nil
case <-srv.quit:
// give back the currently reserved slot
if slot != nil {
srv.peerSlots <- *slot
}
return
}
}
}
// connect to peer via dial out
func (srv *Server) dialPeer(desc *peerAddr, slot int) {
srvlog.Debugf("Dialing %v (slot %d)\n", desc, slot)
conn, err := srv.Dialer.Dial(desc.Network(), desc.String())
if err != nil {
srvlog.Errorf("Dial error: %v", err)
srv.peerSlots <- slot
return
}
go srv.addPeer(conn, desc, slot)
}
// creates the new peer object and inserts it into its slot
func (srv *Server) addPeer(conn net.Conn, desc *peerAddr, slot int) *Peer {
srv.lock.Lock()
defer srv.lock.Unlock()
if !srv.running {
conn.Close()
srv.peerSlots <- slot // release slot
return nil
}
peer := srv.newPeerFunc(srv, conn, desc)
peer.slot = slot
srv.peers[slot] = peer
srv.peerCount++
go func() { peer.loop(); srv.peerDisconnect <- peer }()
return peer
}
// removes peer: sending disconnect msg, stop peer, remove rom list/table, release slot
func (srv *Server) removePeer(peer *Peer) {
srv.lock.Lock()
defer srv.lock.Unlock()
srvlog.Debugf("Removing peer %v %v (slot %v)\n", peer, peer.slot)
if srv.peers[peer.slot] != peer {
srvlog.Warnln("Invalid peer to remove:", peer)
return
}
// remove from list and index
srv.peerCount--
srv.peers[peer.slot] = nil
// release slot to signal need for a new peer, last!
srv.peerSlots <- peer.slot
}
func (srv *Server) verifyPeer(addr *peerAddr) error {
if srv.Blacklist.Exists(addr.Pubkey) {
return errors.New("blacklisted")
}
if bytes.Equal(srv.Identity.Pubkey()[1:], addr.Pubkey) {
return newPeerError(errPubkeyForbidden, "not allowed to connect to srv")
}
srv.lock.RLock()
defer srv.lock.RUnlock()
for _, peer := range srv.peers {
if peer != nil {
id := peer.Identity()
if id != nil && bytes.Equal(id.Pubkey(), addr.Pubkey) {
return errors.New("already connected")
}
}
}
return nil
}
type Blacklist interface {
Get([]byte) (bool, error)
Put([]byte) error
Delete([]byte) error
Exists(pubkey []byte) (ok bool)
}
type BlacklistMap struct {
blacklist map[string]bool
lock sync.RWMutex
}
func NewBlacklist() *BlacklistMap {
return &BlacklistMap{
blacklist: make(map[string]bool),
}
}
func (self *BlacklistMap) Get(pubkey []byte) (bool, error) {
self.lock.RLock()
defer self.lock.RUnlock()
v, ok := self.blacklist[string(pubkey)]
var err error
if !ok {
err = fmt.Errorf("not found")
}
return v, err
}
func (self *BlacklistMap) Exists(pubkey []byte) (ok bool) {
self.lock.RLock()
defer self.lock.RUnlock()
_, ok = self.blacklist[string(pubkey)]
return
}
func (self *BlacklistMap) Put(pubkey []byte) error {
self.lock.RLock()
defer self.lock.RUnlock()
self.blacklist[string(pubkey)] = true
return nil
}
func (self *BlacklistMap) Delete(pubkey []byte) error {
self.lock.RLock()
defer self.lock.RUnlock()
delete(self.blacklist, string(pubkey))
return nil
}