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server.go
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server.go
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package server
import (
"container/list"
"net"
"strings"
"sync"
"time"
"google.golang.org/protobuf/proto"
"github.com/iotaledger/hive.go/autopeering/netutil"
"github.com/iotaledger/hive.go/autopeering/peer"
pb "github.com/iotaledger/hive.go/autopeering/server/proto"
"github.com/iotaledger/hive.go/crypto/identity"
"github.com/iotaledger/hive.go/lo"
"github.com/iotaledger/hive.go/logger"
"github.com/iotaledger/hive.go/runtime/timeutil"
)
const (
// ResponseTimeout specifies the time limit after which a response must have been received.
ResponseTimeout = 500 * time.Millisecond
)
// NetConn defines the interface required for a connection.
type NetConn interface {
// Close closes the connection.
Close() error
// LocalAddr returns the local network address.
LocalAddr() net.Addr
// ReadFromUDP acts like ReadFrom but returns a UDPAddr.
ReadFromUDP([]byte) (int, *net.UDPAddr, error)
// WriteToUDP acts like WriteTo but takes a UDPAddr.
WriteToUDP([]byte, *net.UDPAddr) (int, error)
}
// Server offers the functionality to start a server that handles requests and responses from peers.
type Server struct {
local *peer.Local
conn NetConn
handlers []Handler
log *logger.Logger
network string
closeOnce sync.Once
wg sync.WaitGroup
addReplyMatcher chan *replyMatcher
replyReceived chan reply
closing chan struct{} // if this channel gets closed all pending waits should terminate
}
// a replyMatcher stores the information required to identify and react to an expected replay.
type replyMatcher struct {
// fromIP must match the sender of the reply
fromIP net.IP
// fromID must match the sender ID
fromID identity.ID
// mtype must match the type of the reply
mtype MType
// deadline when the request must complete
deadline time.Time
// callback is called when a matching reply arrives
// If it returns true, the reply is acceptable.
callback func(msg Message) bool
// errc receives nil when the callback indicates completion or an
// error if no further reply is received within the timeout
errc chan error
}
// reply is a reply packet from a certain peer.
type reply struct {
fromIP net.IP
fromID identity.ID
msg Message // the actual reply message
matchedRequest chan<- bool // a matching request is indicated via this channel
}
// Serve starts a new peer server using the given transport layer for communication.
// Sent data is signed using the identity of the local peer,
// received data with a valid peer signature is handled according to the provided Handler.
func Serve(local *peer.Local, conn NetConn, log *logger.Logger, h ...Handler) *Server {
srv := &Server{
local: local,
conn: conn,
handlers: h,
log: log,
network: local.Network(),
addReplyMatcher: make(chan *replyMatcher),
replyReceived: make(chan reply),
closing: make(chan struct{}),
}
srv.wg.Add(2)
go srv.replyLoop()
go srv.readLoop()
log.Debugw("server started",
"network", srv.LocalAddr().Network(),
"address", srv.LocalAddr().String(),
"#handlers", len(h))
return srv
}
// Close shuts down the server.
func (s *Server) Close() {
s.closeOnce.Do(func() {
close(s.closing)
s.conn.Close()
s.wg.Wait()
})
}
// Local returns the the local peer.
func (s *Server) Local() *peer.Local {
return s.local
}
// LocalAddr returns the address of the local peer in string form.
func (s *Server) LocalAddr() *net.UDPAddr {
return s.conn.LocalAddr().(*net.UDPAddr)
}
// Send sends a message to the given address.
func (s *Server) Send(toAddr *net.UDPAddr, data []byte) {
pkt := s.encode(data)
s.write(pkt, toAddr)
}
// SendExpectingReply sends a message to the given address and tells the Server
// to expect a reply message with the given specifications.
// If eventually nil is returned, a matching message was received.
func (s *Server) SendExpectingReply(toAddr *net.UDPAddr, toID identity.ID, data []byte, replyType MType, callback func(Message) bool) <-chan error {
errc := s.expectReply(toAddr.IP, toID, replyType, callback)
s.Send(toAddr, data)
return errc
}
// expectReply tells the Server to expect a reply message with the given specifications.
// If eventually nil is returned, a matching message was received.
func (s *Server) expectReply(fromIP net.IP, fromID identity.ID, mtype MType, callback func(Message) bool) <-chan error {
ch := make(chan error, 1)
m := &replyMatcher{fromIP: fromIP, fromID: fromID, mtype: mtype, callback: callback, errc: ch}
select {
case s.addReplyMatcher <- m:
case <-s.closing:
ch <- ErrClosed
}
return ch
}
// IsExpectedReply checks whether the given testMessage matches an expected reply added with SendExpectingReply.
func (s *Server) IsExpectedReply(fromIP net.IP, fromID identity.ID, msg Message) bool {
matched := make(chan bool, 1)
select {
case s.replyReceived <- reply{fromIP, fromID, msg, matched}:
// wait for matcher and return whether a matching request was found
return <-matched
case <-s.closing:
return false
}
}
// Loop checking for matching replies.
func (s *Server) replyLoop() {
defer s.wg.Done()
var (
matcherList = list.New()
timeout = time.NewTimer(0)
)
defer timeutil.CleanupTimer(timeout)
<-timeout.C // ignore first timeout
for {
// Set the timer so that it fires when the next reply expires
if e := matcherList.Front(); e != nil {
// the first element always has the closest deadline
m := e.Value.(*replyMatcher)
timeout.Reset(time.Until(m.deadline))
} else {
timeout.Stop()
}
select {
// add a new matcher to the list
case s := <-s.addReplyMatcher:
s.deadline = time.Now().Add(ResponseTimeout)
matcherList.PushBack(s)
// on reply received, check all matchers for fits
case r := <-s.replyReceived:
matched := false
for e := matcherList.Front(); e != nil; e = e.Next() {
m := e.Value.(*replyMatcher)
if m.mtype == r.msg.Type() && m.fromID == r.fromID && m.fromIP.Equal(r.fromIP) {
if m.callback(r.msg) {
// request has been matched
matched = true
m.errc <- nil
matcherList.Remove(e)
}
}
}
r.matchedRequest <- matched
// on timeout, check for expired matchers
case <-timeout.C:
now := time.Now()
// notify and remove any expired matchers
for e := matcherList.Front(); e != nil; e = e.Next() {
m := e.Value.(*replyMatcher)
if now.After(m.deadline) || now.Equal(m.deadline) {
m.errc <- ErrTimeout
matcherList.Remove(e)
}
}
// on close, notice all the matchers
case <-s.closing:
for e := matcherList.Front(); e != nil; e = e.Next() {
e.Value.(*replyMatcher).errc <- ErrClosed
}
return
}
}
}
func (s *Server) write(pkt *pb.Packet, toAddr *net.UDPAddr) {
b, err := proto.Marshal(pkt)
if err != nil {
s.log.Error("marshal error", "err", err)
return
}
if l := len(b); l > MaxPacketSize {
s.log.Error("packet too large", "size", l, "max", MaxPacketSize)
return
}
_, err = s.conn.WriteToUDP(b, toAddr)
if err != nil {
s.log.Debugw("failed to write packet", "addr", toAddr, "err", err)
}
}
// encodes a message as a data packet that can be written.
func (s *Server) encode(data []byte) *pb.Packet {
if len(data) == 0 {
panic("server: no data")
}
return &pb.Packet{
PublicKey: lo.PanicOnErr(s.local.PublicKey().Bytes()),
Signature: lo.PanicOnErr(s.local.Sign(data).Bytes()),
Data: append([]byte(nil), data...),
}
}
func (s *Server) readLoop() {
defer s.wg.Done()
buffer := make([]byte, MaxPacketSize)
for {
n, fromAddr, err := s.conn.ReadFromUDP(buffer)
if netutil.IsTemporaryError(err) {
// ignore temporary read errors.
s.log.Debugw("temporary read error", "err", err)
continue
}
// return from the loop on all other errors
if err != nil {
// The error that is returned for an operation on a closed network connection is not exported.
// This is the only way to check for the error. See issues #4373 and #19252.
if !strings.Contains(err.Error(), "use of closed network connection") {
s.log.Warnw("read error", "err", err)
}
s.log.Debug("reading stopped")
return
}
pkt := new(pb.Packet)
if err := proto.Unmarshal(buffer[:n], pkt); err != nil {
s.log.Debugw("bad packet", "from", fromAddr, "err", err)
continue
}
if err := s.handlePacket(pkt, fromAddr); err != nil {
s.log.Debugw("failed to handle packet", "from", fromAddr, "err", err)
}
}
}
func (s *Server) handlePacket(pkt *pb.Packet, fromAddr *net.UDPAddr) error {
data, from, err := decode(pkt)
if err != nil {
return err
}
for _, handler := range s.handlers {
ok, err := handler.HandleMessage(s, fromAddr, from, data)
if ok {
return err
}
}
return ErrInvalidMessage
}
func decode(pkt *pb.Packet) ([]byte, *identity.Identity, error) {
if len(pkt.GetData()) == 0 {
return nil, nil, ErrNoMessage
}
key, err := peer.RecoverKeyFromSignedData(pkt)
if err != nil {
return nil, nil, err
}
return pkt.GetData(), identity.New(key), nil
}