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package websocket_test
import (
"context"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"log"
"net"
"net/http"
"time"
"golang.org/x/time/rate"
"golang.org/x/xerrors"
"nhooyr.io/websocket"
)
func Example_echo() {
l, err := net.Listen("tcp", "localhost:0")
if err != nil {
log.Fatalf("failed to listen: %v", err)
return
}
defer l.Close()
s := &http.Server{
Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
err := echoServer(w, r)
if err != nil {
log.Printf("echo server: %v", err)
}
}),
ReadTimeout: time.Second * 15,
WriteTimeout: time.Second * 15,
}
defer s.Close()
go func() {
err := s.Serve(l)
if err != http.ErrServerClosed {
log.Fatalf("failed to listen and serve: %v", err)
}
}()
err = client("ws://" + l.Addr().String())
if err != nil {
log.Fatalf("client failed: %v", err)
}
// Output:
// {"i":0}
// {"i":1}
// {"i":2}
// {"i":3}
// {"i":4}
}
func echoServer(w http.ResponseWriter, r *http.Request) error {
c, err := websocket.Accept(w, r, websocket.AcceptOptions{
Subprotocols: []string{"echo"},
})
if err != nil {
return err
}
defer c.Close(websocket.StatusInternalError, "")
if c.Subprotocol() == "" {
c.Close(websocket.StatusPolicyViolation, "cannot communicate with the default protocol")
return xerrors.Errorf("client does not speak echo sub protocol")
}
ctx := r.Context()
l := rate.NewLimiter(rate.Every(time.Millisecond*100), 10)
for {
err = echo(ctx, c, l)
if err != nil {
return xerrors.Errorf("failed to echo: %w", err)
}
}
}
func echo(ctx context.Context, c *websocket.Conn, l *rate.Limiter) error {
ctx, cancel := context.WithTimeout(ctx, time.Minute)
defer cancel()
err := l.Wait(ctx)
if err != nil {
return err
}
typ, r, err := c.Reader(ctx)
if err != nil {
return err
}
r = io.LimitReader(r, 32768)
w, err := c.Writer(ctx, typ)
if err != nil {
return err
}
_, err = io.Copy(w, r)
if err != nil {
return err
}
err = w.Close()
return err
}
func client(url string) error {
ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
defer cancel()
c, _, err := websocket.Dial(ctx, url, websocket.DialOptions{
Subprotocols: []string{"echo"},
})
if err != nil {
return err
}
defer c.Close(websocket.StatusInternalError, "")
for i := 0; i < 5; i++ {
w, err := c.Writer(ctx, websocket.MessageText)
if err != nil {
return err
}
e := json.NewEncoder(w)
err = e.Encode(map[string]int{
"i": i,
})
if err != nil {
return err
}
err = w.Close()
if err != nil {
return err
}
typ, r, err := c.Reader(ctx)
if err != nil {
return err
}
if typ != websocket.MessageText {
return xerrors.Errorf("expected text message but got %v", typ)
}
msg2, err := ioutil.ReadAll(r)
if err != nil {
return err
}
fmt.Printf("%s", msg2)
}
c.Close(websocket.StatusNormalClosure, "")
return nil
}