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package centrifuge
import (
"fmt"
"net/http"
"net/url"
"strings"
"sync"
"time"
"github.com/centrifugal/centrifuge/internal/cancelctx"
"github.com/centrifugal/centrifuge/internal/timers"
"github.com/gorilla/websocket"
)
const (
transportWebsocket = "websocket"
)
// websocketTransport is a wrapper struct over websocket connection to fit session
// interface so client will accept it.
type websocketTransport struct {
mu sync.RWMutex
conn *websocket.Conn
closed bool
closeCh chan struct{}
graceCh chan struct{}
opts websocketTransportOptions
pingTimer *time.Timer
}
type websocketTransportOptions struct {
encType EncodingType
protoType ProtocolType
pingInterval time.Duration
writeTimeout time.Duration
compressionMinSize int
}
func newWebsocketTransport(conn *websocket.Conn, opts websocketTransportOptions, graceCh chan struct{}) *websocketTransport {
transport := &websocketTransport{
conn: conn,
closeCh: make(chan struct{}),
graceCh: graceCh,
opts: opts,
}
if opts.pingInterval > 0 {
transport.addPing()
}
return transport
}
func (t *websocketTransport) ping() {
select {
case <-t.closeCh:
return
default:
deadline := time.Now().Add(t.opts.pingInterval / 2)
err := t.conn.WriteControl(websocket.PingMessage, []byte("ping"), deadline)
if err != nil {
_ = t.Close(DisconnectServerError)
return
}
t.addPing()
}
}
func (t *websocketTransport) addPing() {
t.mu.Lock()
if t.closed {
t.mu.Unlock()
return
}
t.pingTimer = time.AfterFunc(t.opts.pingInterval, t.ping)
t.mu.Unlock()
}
// Name returns name of transport.
func (t *websocketTransport) Name() string {
return transportWebsocket
}
// Protocol returns transport protocol.
func (t *websocketTransport) Protocol() ProtocolType {
return t.opts.protoType
}
// Encoding returns transport encoding.
func (t *websocketTransport) Encoding() EncodingType {
return t.opts.encType
}
// Write data to transport.
func (t *websocketTransport) Write(data []byte) error {
select {
case <-t.closeCh:
return nil
default:
if t.opts.compressionMinSize > 0 {
t.conn.EnableWriteCompression(len(data) > t.opts.compressionMinSize)
}
if t.opts.writeTimeout > 0 {
_ = t.conn.SetWriteDeadline(time.Now().Add(t.opts.writeTimeout))
}
var messageType = websocket.TextMessage
if t.Protocol() == ProtocolTypeProtobuf {
messageType = websocket.BinaryMessage
}
err := t.conn.WriteMessage(messageType, data)
if err != nil {
return err
}
if t.opts.writeTimeout > 0 {
_ = t.conn.SetWriteDeadline(time.Time{})
}
return nil
}
}
const closeFrameWait = 5 * time.Second
// Close closes transport.
func (t *websocketTransport) Close(disconnect *Disconnect) error {
t.mu.Lock()
if t.closed {
t.mu.Unlock()
return nil
}
t.closed = true
if t.pingTimer != nil {
t.pingTimer.Stop()
}
close(t.closeCh)
t.mu.Unlock()
if disconnect != nil {
msg := websocket.FormatCloseMessage(int(disconnect.Code), disconnect.CloseText())
err := t.conn.WriteControl(websocket.CloseMessage, msg, time.Now().Add(time.Second))
if err != nil {
return t.conn.Close()
}
select {
case <-t.graceCh:
default:
// Wait for closing handshake completion.
tm := timers.AcquireTimer(closeFrameWait)
select {
case <-t.graceCh:
case <-tm.C:
}
timers.ReleaseTimer(tm)
}
return t.conn.Close()
}
return t.conn.Close()
}
// Defaults.
const (
DefaultWebsocketPingInterval = 25 * time.Second
DefaultWebsocketWriteTimeout = 1 * time.Second
DefaultWebsocketMessageSizeLimit = 65536 // 64KB
)
// WebsocketConfig represents config for WebsocketHandler.
type WebsocketConfig struct {
// CompressionLevel sets a level for websocket compression.
// See possible value description at https://golang.org/pkg/compress/flate/#NewWriter
CompressionLevel int
// CompressionMinSize allows to set minimal limit in bytes for
// message to use compression when writing it into client connection.
// By default it's 0 - i.e. all messages will be compressed when
// WebsocketCompression enabled and compression negotiated with client.
CompressionMinSize int
// ReadBufferSize is a parameter that is used for raw websocket Upgrader.
// If set to zero reasonable default value will be used.
ReadBufferSize int
// WriteBufferSize is a parameter that is used for raw websocket Upgrader.
// If set to zero reasonable default value will be used.
WriteBufferSize int
// MessageSizeLimit sets the maximum size in bytes of allowed message from client.
// By default DefaultWebsocketMaxMessageSize will be used.
MessageSizeLimit int
// CheckOrigin func to provide custom origin check logic.
// nil means allow all origins.
CheckOrigin func(r *http.Request) bool
// PingInterval sets interval server will send ping messages to clients.
// By default DefaultPingInterval will be used.
PingInterval time.Duration
// WriteTimeout is maximum time of write message operation.
// Slow client will be disconnected.
// By default DefaultWebsocketWriteTimeout will be used.
WriteTimeout time.Duration
// Compression allows to enable websocket permessage-deflate
// compression support for raw websocket connections. It does
// not guarantee that compression will be used - i.e. it only
// says that server will try to negotiate it with client.
Compression bool
// UseWriteBufferPool enables using buffer pool for writes.
UseWriteBufferPool bool
}
// WebsocketHandler handles WebSocket client connections. WebSocket protocol
// is a bidirectional connection between a client an a server for low-latency
// communication.
type WebsocketHandler struct {
node *Node
upgrade *websocket.Upgrader
config WebsocketConfig
}
var writeBufferPool = &sync.Pool{}
// NewWebsocketHandler creates new WebsocketHandler.
func NewWebsocketHandler(n *Node, c WebsocketConfig) *WebsocketHandler {
upgrade := &websocket.Upgrader{
ReadBufferSize: c.ReadBufferSize,
EnableCompression: c.Compression,
}
if c.UseWriteBufferPool {
upgrade.WriteBufferPool = writeBufferPool
} else {
upgrade.WriteBufferSize = c.WriteBufferSize
}
if c.CheckOrigin != nil {
upgrade.CheckOrigin = c.CheckOrigin
} else {
upgrade.CheckOrigin = sameHostOriginCheck(n)
}
return &WebsocketHandler{
node: n,
config: c,
upgrade: upgrade,
}
}
func (s *WebsocketHandler) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
incTransportConnect(transportWebsocket)
compression := s.config.Compression
compressionLevel := s.config.CompressionLevel
compressionMinSize := s.config.CompressionMinSize
conn, err := s.upgrade.Upgrade(rw, r, nil)
if err != nil {
s.node.logger.log(newLogEntry(LogLevelDebug, "websocket upgrade error", map[string]interface{}{"error": err.Error()}))
return
}
if compression {
err := conn.SetCompressionLevel(compressionLevel)
if err != nil {
s.node.logger.log(newLogEntry(LogLevelError, "websocket error setting compression level", map[string]interface{}{"error": err.Error()}))
}
}
pingInterval := s.config.PingInterval
if pingInterval == 0 {
pingInterval = DefaultWebsocketPingInterval
}
writeTimeout := s.config.WriteTimeout
if writeTimeout == 0 {
writeTimeout = DefaultWebsocketWriteTimeout
}
messageSizeLimit := s.config.MessageSizeLimit
if messageSizeLimit == 0 {
messageSizeLimit = DefaultWebsocketMessageSizeLimit
}
if messageSizeLimit > 0 {
conn.SetReadLimit(int64(messageSizeLimit))
}
if pingInterval > 0 {
pongWait := pingInterval * 10 / 9
_ = conn.SetReadDeadline(time.Now().Add(pongWait))
conn.SetPongHandler(func(string) error {
_ = conn.SetReadDeadline(time.Now().Add(pongWait))
return nil
})
}
var protocol = ProtocolTypeJSON
if r.URL.Query().Get("format") == "protobuf" || r.URL.Query().Get("protocol") == "protobuf" {
protocol = ProtocolTypeProtobuf
}
var enc = EncodingTypeJSON
if r.URL.Query().Get("encoding") == "binary" {
enc = EncodingTypeBinary
}
// Separate goroutine for better GC of caller's data.
go func() {
opts := websocketTransportOptions{
pingInterval: pingInterval,
writeTimeout: writeTimeout,
compressionMinSize: compressionMinSize,
encType: enc,
protoType: protocol,
}
graceCh := make(chan struct{})
transport := newWebsocketTransport(conn, opts, graceCh)
select {
case <-s.node.NotifyShutdown():
_ = transport.Close(DisconnectShutdown)
return
default:
}
ctxCh := make(chan struct{})
defer close(ctxCh)
c, closeFn, err := NewClient(cancelctx.New(r.Context(), ctxCh), s.node, transport)
if err != nil {
s.node.logger.log(newLogEntry(LogLevelError, "error creating client", map[string]interface{}{"transport": transportWebsocket}))
return
}
defer func() { _ = closeFn() }()
s.node.logger.log(newLogEntry(LogLevelDebug, "client connection established", map[string]interface{}{"client": c.ID(), "transport": transportWebsocket}))
defer func(started time.Time) {
s.node.logger.log(newLogEntry(LogLevelDebug, "client connection completed", map[string]interface{}{"client": c.ID(), "transport": transportWebsocket, "duration": time.Since(started)}))
}(time.Now())
for {
_, data, err := conn.ReadMessage()
if err != nil {
break
}
closed := !c.Handle(data)
if closed {
break
}
}
// https://github.com/gorilla/websocket/issues/448
conn.SetPingHandler(nil)
conn.SetPongHandler(nil)
conn.SetCloseHandler(nil)
_ = conn.SetReadDeadline(time.Now().Add(closeFrameWait))
for {
if _, _, err := conn.NextReader(); err != nil {
close(graceCh)
break
}
}
}()
}
func sameHostOriginCheck(n *Node) func(r *http.Request) bool {
return func(r *http.Request) bool {
err := checkSameHost(r)
if err != nil {
n.logger.log(newLogEntry(LogLevelInfo, "origin check failure", map[string]interface{}{"error": err.Error()}))
return false
}
return true
}
}
func checkSameHost(r *http.Request) error {
origin := r.Header.Get("Origin")
if origin == "" {
return nil
}
u, err := url.Parse(origin)
if err != nil {
return fmt.Errorf("failed to parse Origin header %q: %w", origin, err)
}
if strings.EqualFold(r.Host, u.Host) {
return nil
}
return fmt.Errorf("request Origin %q is not authorized for Host %q", origin, r.Host)
}
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