178 lines
3.2 KiB
Go
178 lines
3.2 KiB
Go
// Package web contains the web handler including websocket support
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package web
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import (
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"errors"
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"fmt"
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"io"
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"net"
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"net/http"
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"net/http/httputil"
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"net/url"
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"strings"
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"github.com/micro/go-micro/api"
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"github.com/micro/go-micro/api/handler"
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"github.com/micro/go-micro/selector"
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)
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const (
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Handler = "web"
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)
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type webHandler struct {
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opts handler.Options
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s *api.Service
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}
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func (wh *webHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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service, err := wh.getService(r)
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if err != nil {
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w.WriteHeader(500)
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return
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}
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if len(service) == 0 {
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w.WriteHeader(404)
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return
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}
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rp, err := url.Parse(service)
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if err != nil {
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w.WriteHeader(500)
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return
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}
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if isWebSocket(r) {
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wh.serveWebSocket(rp.Host, w, r)
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return
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}
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httputil.NewSingleHostReverseProxy(rp).ServeHTTP(w, r)
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}
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// getService returns the service for this request from the selector
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func (wh *webHandler) getService(r *http.Request) (string, error) {
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var service *api.Service
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if wh.s != nil {
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// we were given the service
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service = wh.s
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} else if wh.opts.Router != nil {
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// try get service from router
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s, err := wh.opts.Router.Route(r)
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if err != nil {
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return "", err
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}
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service = s
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} else {
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// we have no way of routing the request
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return "", errors.New("no route found")
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}
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// create a random selector
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next := selector.Random(service.Services)
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// get the next node
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s, err := next()
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if err != nil {
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return "", nil
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}
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return fmt.Sprintf("http://%s:%d", s.Address, s.Port), nil
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}
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// serveWebSocket used to serve a web socket proxied connection
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func (wh *webHandler) serveWebSocket(host string, w http.ResponseWriter, r *http.Request) {
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req := new(http.Request)
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*req = *r
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if len(host) == 0 {
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http.Error(w, "invalid host", 500)
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return
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}
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// set x-forward-for
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if clientIP, _, err := net.SplitHostPort(r.RemoteAddr); err == nil {
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if ips, ok := req.Header["X-Forwarded-For"]; ok {
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clientIP = strings.Join(ips, ", ") + ", " + clientIP
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}
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req.Header.Set("X-Forwarded-For", clientIP)
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}
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// connect to the backend host
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conn, err := net.Dial("tcp", host)
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if err != nil {
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http.Error(w, err.Error(), 500)
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return
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}
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// hijack the connection
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hj, ok := w.(http.Hijacker)
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if !ok {
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http.Error(w, "failed to connect", 500)
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return
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}
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nc, _, err := hj.Hijack()
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if err != nil {
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return
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}
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defer nc.Close()
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defer conn.Close()
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if err = req.Write(conn); err != nil {
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return
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}
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errCh := make(chan error, 2)
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cp := func(dst io.Writer, src io.Reader) {
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_, err := io.Copy(dst, src)
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errCh <- err
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}
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go cp(conn, nc)
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go cp(nc, conn)
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<-errCh
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}
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func isWebSocket(r *http.Request) bool {
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contains := func(key, val string) bool {
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vv := strings.Split(r.Header.Get(key), ",")
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for _, v := range vv {
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if val == strings.ToLower(strings.TrimSpace(v)) {
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return true
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}
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}
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return false
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}
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if contains("Connection", "upgrade") && contains("Upgrade", "websocket") {
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return true
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}
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return false
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}
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func (wh *webHandler) String() string {
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return "web"
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}
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func NewHandler(opts ...handler.Option) handler.Handler {
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return &webHandler{
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opts: handler.NewOptions(opts...),
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}
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}
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func WithService(s *api.Service, opts ...handler.Option) handler.Handler {
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options := handler.NewOptions(opts...)
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return &webHandler{
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opts: options,
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s: s,
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}
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}
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