/
rawsocketpeer.go
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/
rawsocketpeer.go
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package transport
import (
"crypto/tls"
"errors"
"fmt"
"io"
"io/ioutil"
"net"
"time"
"github.com/Anth80/nexus/stdlog"
"github.com/Anth80/nexus/transport/serialize"
"github.com/Anth80/nexus/wamp"
)
// rawSocketPeer implements the Peer interface, connecting the Send and Recv
// methods to a socket.
type rawSocketPeer struct {
conn net.Conn
serializer serialize.Serializer
sendLimit int
recvLimit int
// Used to signal the socket is closed explicitly.
closed chan struct{}
// Channels communicate with router.
rd chan wamp.Message
wr chan wamp.Message
writerDone chan struct{}
log stdlog.StdLog
}
const (
// Serializers
rawsocketJSON = 1
rawsocketMsgpack = 2
// compatibility with crossbar.io router.
rawsocketCBOR = 3
// RawSocket header ID.
magic = 0x7f
)
// ConnectRawSocketPeer creates a new rawSocketPeer with the specified config,
// and connects it to the WAMP router at the specified address. The network
// and address parameters are documented here:
// https://golang.org/pkg/net/#Dial
//
// If recvLimit is > 0, then the client will not receive messages with size
// larger than the nearest power of 2 greater than or equal to recvLimit. If
// recvLimit is <= 0, then the default of 16M is used.
func ConnectRawSocketPeer(network, address string, serialization serialize.Serialization, logger stdlog.StdLog, recvLimit int) (wamp.Peer, error) {
err := checkNetworkType(network)
if err != nil {
return nil, err
}
protocol, err := getProtoByte(serialization)
if err != nil {
return nil, err
}
conn, err := net.Dial(network, address)
if err != nil {
return nil, err
}
peer, err := clientHandshake(conn, logger, protocol, recvLimit)
if err != nil {
conn.Close()
return nil, err
}
return peer, nil
}
// ConnectTlsRawSocketPeer creates a new rawSocketPeer with the specified
// config, and connects it, using TLS, to the WAMP router at the specified
// address. The network, address, and tlscfg parameters are documented here:
// https://golang.org/pkg/crypto/tls/#Dial
//
// If recvLimit is > 0, then the client will not receive messages with size
// larger than the nearest power of 2 greater than or equal to recvLimit. If
// recvLimit is <= 0, then the default of 16M is used.
func ConnectTlsRawSocketPeer(network, address string, serialization serialize.Serialization, tlsConfig *tls.Config, logger stdlog.StdLog, recvLimit int) (wamp.Peer, error) {
err := checkNetworkType(network)
if err != nil {
return nil, err
}
protocol, err := getProtoByte(serialization)
if err != nil {
return nil, err
}
conn, err := tls.Dial(network, address, tlsConfig)
if err != nil {
return nil, err
}
peer, err := clientHandshake(conn, logger, protocol, recvLimit)
if err != nil {
conn.Close()
return nil, err
}
return peer, nil
}
// AcceptRawSocket handles the client handshake and returns a rawSocketPeer.
//
// If recvLimit is > 0, then the client will not receive messages with size
// larger than the nearest power of 2 greater than or equal to recvLimit. If
// recvLimit is <= 0, then the default of 16M is used.
func AcceptRawSocket(conn net.Conn, logger stdlog.StdLog, recvLimit int) (wamp.Peer, error) {
peer, err := serverHandshake(conn, logger, recvLimit)
if err != nil {
conn.Close()
return nil, err
}
return peer, nil
}
// newRawSocketPeer creates a rawsocket peer from an existing socket
// connection. This is used by clients connecting to the WAMP router, and by
// servers to handle connections from clients.
func newRawSocketPeer(conn net.Conn, serializer serialize.Serializer, logger stdlog.StdLog, sendLimit, recvLimit int) *rawSocketPeer {
rs := &rawSocketPeer{
conn: conn,
serializer: serializer,
sendLimit: sendLimit,
recvLimit: recvLimit,
closed: make(chan struct{}),
writerDone: make(chan struct{}),
// The router will read from this channel and immediately dispatch the
// message to the broker or dealer. Therefore this channel can be
// unbuffered.
rd: make(chan wamp.Message),
// The channel for messages being written to the socket should be
// large enough to prevent blocking while waiting for a slow socket
// to send messages. For this reason it may be necessary for these
// messages to be put into an outbound queue that can grow.
wr: make(chan wamp.Message, outQueueSize),
log: logger,
}
// Sending to and receiving from socket is handled concurrently.
go rs.recvHandler()
go rs.sendHandler()
return rs
}
func (rs *rawSocketPeer) Recv() <-chan wamp.Message { return rs.rd }
func (rs *rawSocketPeer) TrySend(msg wamp.Message) error {
select {
case rs.wr <- msg:
return nil
default:
}
select {
case rs.wr <- msg:
case <-time.After(time.Second):
return errors.New("blocked")
}
return nil
}
func (rs *rawSocketPeer) Send(msg wamp.Message) error {
rs.wr <- msg
return nil
}
// Close closes the rawsocket peer. This closes the local send channel, and
// sends a close control message to the socket to tell the other side to
// close.
//
// *** Do not call Send after calling Close. ***
func (rs *rawSocketPeer) Close() {
// Tell sendHandler to exit, allowing it to finish sending any queued
// messages. Do not close wr channel in case there are incoming messages
// during close.
rs.wr <- nil
<-rs.writerDone
// Tell recvHandler to close.
close(rs.closed)
// Ignore errors since socket may have been closed by other side first in
// response to a goodbye message.
rs.conn.Close()
}
// sendHandler pulls messages from the write channel, and pushes them to the
// socket.
func (rs *rawSocketPeer) sendHandler() {
defer close(rs.writerDone)
for msg := range rs.wr {
if msg == nil {
return
}
b, err := rs.serializer.Serialize(msg)
if err != nil {
rs.log.Print(err)
continue
}
if len(b) > rs.sendLimit {
rs.log.Println("Message size", len(b), "exceeds limit of",
rs.sendLimit)
continue
}
lenBytes := intToBytes(len(b))
header := []byte{0x0, lenBytes[0], lenBytes[1], lenBytes[2]}
if _, err = rs.conn.Write(header); err != nil {
if !wamp.IsGoodbyeAck(msg) {
rs.log.Println("Error writing header:", err)
}
continue
}
if _, err = rs.conn.Write(b); err != nil {
if !wamp.IsGoodbyeAck(msg) {
rs.log.Println("Error writing message:", msg, err)
}
continue
}
}
}
// recvHandler pulls messages from the socket and pushes them to the read
// channel.
func (rs *rawSocketPeer) recvHandler() {
// When done, close read channel to cause router to remove session if not
// already removed.
defer close(rs.rd)
MsgLoop:
for {
var header [4]byte
_, err := io.ReadFull(rs.conn, header[:])
if err != nil {
select {
case <-rs.closed:
// Peer was closed explicitly. sendHandler should have already
// been told to exit.
default:
// Peer received control message to close. Cause sendHandler
// to exit without closing the write channel (in case writes
// still happening) and allow it to finish sending any queued
// messages.
rs.wr <- nil
<-rs.writerDone
// Close socket connection.
rs.conn.Close()
}
return
}
length := bytesToInt(header[1:])
if length > rs.recvLimit {
rs.log.Print("Received message that exceeded size limit, closing")
rs.conn.Close()
break
}
var msg wamp.Message
switch header[0] & 0x07 {
case 0: // WAMP message
buf := make([]byte, length)
_, err = io.ReadFull(rs.conn, buf)
if err != nil {
rs.log.Println("Error reading message:", err)
rs.conn.Close()
return
}
msg, err = rs.serializer.Deserialize(buf)
if err != nil {
// TODO: something more than merely logging?
rs.log.Println("Cannot deserialize peer message:", err)
continue MsgLoop
}
case 1: // PING
header[0] = 0x02
if _, err = rs.conn.Write(header[:]); err != nil {
rs.log.Println("Error writing header responding to PING:", err)
rs.conn.Close()
return
}
if _, err = io.CopyN(rs.conn, rs.conn, int64(length)); err != nil {
rs.log.Println("Error responding to PING:", err)
rs.conn.Close()
return
}
continue MsgLoop
case 2: // PONG
_, err = io.CopyN(ioutil.Discard, rs.conn, int64(length))
if err != nil {
rs.log.Println("Error reading PONG:", err)
rs.conn.Close()
return
}
continue MsgLoop
}
// It is OK for the router to block a client since routing should be
// very quick compared to the time to transfer a message over the
// socket, and a blocked client will not block other clients.
//
// Need to wake up on rs.closed so this goroutine can exit in the case
// that messages are not being read from the peer and prevent this
// write from completing.
select {
case rs.rd <- msg:
case <-rs.closed:
// If closed, try for one second to send the last message and then
// exit recvHandler.
select {
case rs.rd <- msg:
case <-time.After(time.Second):
rs.conn.Close()
return
}
}
}
}
// clientHandshake handles the client-side of a RawSocket transport handshake.
func clientHandshake(conn net.Conn, logger stdlog.StdLog, protocol byte, recvLimit int) (*rawSocketPeer, error) {
maxRecvLen := fitRecvLimit(recvLimit)
_, err := conn.Write([]byte{magic, (maxRecvLen&0xf)<<4 | protocol, 0, 0})
if err != nil {
return nil, fmt.Errorf("error sending handshake: %s", err)
}
var buf [4]byte
if _, err = io.ReadFull(conn, buf[:]); err != nil {
return nil, err
}
if buf[0] != magic {
return nil, errors.New("not a rawsocket handshake")
}
repSerializer := buf[1] & 0xf
if repSerializer == 0 {
errCode := buf[1] >> 4
switch errCode {
case 0:
return nil, errors.New("illegal error code")
case 1:
return nil, errors.New("serializer unsupported")
case 2:
return nil, errors.New("maximum message length unacceptable")
case 3:
return nil, errors.New("use of reserved bits (unsupported feature)")
case 4:
return nil, errors.New("maximum connection count reached")
default:
return nil, fmt.Errorf("unknown error: %d", errCode)
}
}
if repSerializer != protocol {
return nil, errors.New("serializer mismatch")
}
var serializer serialize.Serializer
switch protocol {
case rawsocketJSON:
serializer = &serialize.JSONSerializer{}
case rawsocketMsgpack:
serializer = &serialize.MessagePackSerializer{}
case rawsocketCBOR:
serializer = &serialize.CBORSerializer{}
}
sendLimit := byteToLength(buf[1] >> 4)
recvLimit = byteToLength(maxRecvLen)
return newRawSocketPeer(conn, serializer, logger, sendLimit, recvLimit), nil
}
// serverHandshake handles the server-side of a RawSocket transport handshake.
func serverHandshake(conn net.Conn, logger stdlog.StdLog, recvLimit int) (*rawSocketPeer, error) {
var buf [4]byte
if _, err := io.ReadFull(conn, buf[:]); err != nil {
return nil, err
}
if buf[0] != magic {
return nil, errors.New("not a rawsocket handshake")
}
if buf[2] != 0 || buf[3] != 0 {
conn.Write([]byte{magic, byte(0x3 << 4), 0, 0})
return nil, errors.New("use of reserved bits (unsupported feature)")
}
serialization := buf[1] & 0xf
var serializer serialize.Serializer
switch serialization {
case 0:
return nil, errors.New("illegal serializer value")
case rawsocketJSON:
serializer = &serialize.JSONSerializer{}
case rawsocketMsgpack:
serializer = &serialize.MessagePackSerializer{}
case rawsocketCBOR:
serializer = &serialize.CBORSerializer{}
default:
conn.Write([]byte{magic, byte(0x1 << 4), 0, 0})
return nil, errors.New("serializer unsupported")
}
maxRecvLen := fitRecvLimit(recvLimit)
_, err := conn.Write([]byte{magic, maxRecvLen<<4 | serialization, 0, 0})
if err != nil {
return nil, fmt.Errorf("error sending handshake: %s", err)
}
sendLimit := byteToLength(buf[1] >> 4)
recvLimit = byteToLength(maxRecvLen)
return newRawSocketPeer(conn, serializer, logger, sendLimit, recvLimit), nil
}
// fitRecvLimit finds the power of 2 that is greater than or equal to the specified receive limit. This value is returned as the RawSocket transport byte representation of this value.
func fitRecvLimit(recvLimit int) byte {
if recvLimit > 0 {
for b := byte(0); b < 0xf; b++ {
if byteToLength(b) >= recvLimit {
return b
}
}
}
return 0xf
}
// intToBytes encodes a 24-bit integer into 3 bytes.
func intToBytes(i int) [3]byte {
return [3]byte{
byte((i >> 16) & 0xff),
byte((i >> 8) & 0xff),
byte(i & 0xff),
}
}
// bytesToInt decodes a slice of bytes into an int value.
func bytesToInt(b []byte) int {
var n, shift uint
for i := len(b) - 1; i >= 0; i-- {
n |= uint(b[i]) << shift
shift += 8
}
return int(n)
}
// byteToLength returns the value corresponding to a RawSocket lenght byte.
func byteToLength(b byte) int {
return int(1 << (b + 9))
}
// checkNetworkType checks for acceptable network type.
func checkNetworkType(network string) error {
switch network {
case "tcp", "tcp4", "tcp6", "unix":
default:
return errors.New("unsupported network type: " + network)
}
return nil
}
// getProtoByte returns the RawSocket byte value for a serialization protocol.
func getProtoByte(serialization serialize.Serialization) (byte, error) {
switch serialization {
case serialize.JSON:
return rawsocketJSON, nil
case serialize.MSGPACK:
return rawsocketMsgpack, nil
case serialize.CBOR:
return rawsocketCBOR, nil
default:
return 0, errors.New("serialization not supported by rawsocket")
}
}