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stream.go
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stream.go
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package rpc
import (
"bytes"
"context"
"encoding/json"
"io"
"net/http"
"strings"
"time"
"github.com/asim/go-micro/v3/api"
"github.com/asim/go-micro/v3/client"
raw "github.com/asim/go-micro/v3/codec/bytes"
"github.com/asim/go-micro/v3/logger"
"github.com/asim/go-micro/v3/selector"
"github.com/gobwas/httphead"
"github.com/gobwas/ws"
"github.com/gobwas/ws/wsutil"
)
// serveWebsocket will stream rpc back over websockets assuming json
func serveWebsocket(ctx context.Context, w http.ResponseWriter, r *http.Request, service *api.Service, c client.Client) {
var op ws.OpCode
ct := r.Header.Get("Content-Type")
// Strip charset from Content-Type (like `application/json; charset=UTF-8`)
if idx := strings.IndexRune(ct, ';'); idx >= 0 {
ct = ct[:idx]
}
// check proto from request
switch ct {
case "application/json":
op = ws.OpText
default:
op = ws.OpBinary
}
hdr := make(http.Header)
if proto, ok := r.Header["Sec-Websocket-Protocol"]; ok {
for _, p := range proto {
switch p {
case "binary":
hdr["Sec-WebSocket-Protocol"] = []string{"binary"}
op = ws.OpBinary
}
}
}
payload, err := requestPayload(r)
if err != nil {
if logger.V(logger.ErrorLevel, logger.DefaultLogger) {
logger.Error(err)
}
return
}
upgrader := ws.HTTPUpgrader{Timeout: 5 * time.Second,
Protocol: func(proto string) bool {
if strings.Contains(proto, "binary") {
return true
}
// fallback to support all protocols now
return true
},
Extension: func(httphead.Option) bool {
// disable extensions for compatibility
return false
},
Header: hdr,
}
conn, rw, _, err := upgrader.Upgrade(r, w)
if err != nil {
if logger.V(logger.ErrorLevel, logger.DefaultLogger) {
logger.Error(err)
}
return
}
defer func() {
if err := conn.Close(); err != nil {
if logger.V(logger.ErrorLevel, logger.DefaultLogger) {
logger.Error(err)
}
return
}
}()
var request interface{}
if !bytes.Equal(payload, []byte(`{}`)) {
switch ct {
case "application/json", "":
m := json.RawMessage(payload)
request = &m
default:
request = &raw.Frame{Data: payload}
}
}
// we always need to set content type for message
if ct == "" {
ct = "application/json"
}
req := c.NewRequest(
service.Name,
service.Endpoint.Name,
request,
client.WithContentType(ct),
client.StreamingRequest(),
)
so := selector.WithStrategy(strategy(service.Services))
// create a new stream
stream, err := c.Stream(ctx, req, client.WithSelectOption(so))
if err != nil {
if logger.V(logger.ErrorLevel, logger.DefaultLogger) {
logger.Error(err)
}
return
}
if request != nil {
if err = stream.Send(request); err != nil {
if logger.V(logger.ErrorLevel, logger.DefaultLogger) {
logger.Error(err)
}
return
}
}
go writeLoop(rw, stream)
rsp := stream.Response()
// receive from stream and send to client
for {
select {
case <-ctx.Done():
return
case <-stream.Context().Done():
return
default:
// read backend response body
buf, err := rsp.Read()
if err != nil {
// wants to avoid import grpc/status.Status
if strings.Contains(err.Error(), "context canceled") {
return
}
if logger.V(logger.ErrorLevel, logger.DefaultLogger) {
logger.Error(err)
}
return
}
// write the response
if err := wsutil.WriteServerMessage(rw, op, buf); err != nil {
if logger.V(logger.ErrorLevel, logger.DefaultLogger) {
logger.Error(err)
}
return
}
if err = rw.Flush(); err != nil {
if logger.V(logger.ErrorLevel, logger.DefaultLogger) {
logger.Error(err)
}
return
}
}
}
}
// writeLoop
func writeLoop(rw io.ReadWriter, stream client.Stream) {
// close stream when done
defer stream.Close()
for {
select {
case <-stream.Context().Done():
return
default:
buf, op, err := wsutil.ReadClientData(rw)
if err != nil {
if wserr, ok := err.(wsutil.ClosedError); ok {
switch wserr.Code {
case ws.StatusGoingAway:
// this happens when user leave the page
return
case ws.StatusNormalClosure, ws.StatusNoStatusRcvd:
// this happens when user close ws connection, or we don't get any status
return
}
}
if logger.V(logger.ErrorLevel, logger.DefaultLogger) {
logger.Error(err)
}
return
}
switch op {
default:
// not relevant
continue
case ws.OpText, ws.OpBinary:
break
}
// send to backend
// default to trying json
// if the extracted payload isn't empty lets use it
request := &raw.Frame{Data: buf}
if err := stream.Send(request); err != nil {
if logger.V(logger.ErrorLevel, logger.DefaultLogger) {
logger.Error(err)
}
return
}
}
}
}
func isStream(r *http.Request, srv *api.Service) bool {
// check if it's a web socket
if !isWebSocket(r) {
return false
}
// check if the endpoint supports streaming
for _, service := range srv.Services {
for _, ep := range service.Endpoints {
// skip if it doesn't match the name
if ep.Name != srv.Endpoint.Name {
continue
}
// matched if the name
if v := ep.Metadata["stream"]; v == "true" {
return true
}
}
}
return false
}
func isWebSocket(r *http.Request) bool {
contains := func(key, val string) bool {
vv := strings.Split(r.Header.Get(key), ",")
for _, v := range vv {
if val == strings.ToLower(strings.TrimSpace(v)) {
return true
}
}
return false
}
if contains("Connection", "upgrade") && contains("Upgrade", "websocket") {
return true
}
return false
}