rc: add --rc-files flag to serve files on the rc http server

This enables building a browser based UI for rclone

fs/rc/rc.go

@@ -10,6 +10,7 @@ package rc
 import (
 	"encoding/json"
 	"io"
+	"mime"
 	"net/http"
 	_ "net/http/pprof" // install the pprof http handlers
 	"strings"
@@ -17,12 +18,14 @@ import (
 	"github.com/ncw/rclone/cmd/serve/httplib"
 	"github.com/ncw/rclone/fs"
 	"github.com/pkg/errors"
+	"github.com/skratchdot/open-golang/open"
 )
 
 // Options contains options for the remote control server
 type Options struct {
 	HTTPOptions httplib.Options
-	Enabled     bool
+	Enabled     bool   // set to enable the server
+	Files       string // set to enable serving files
 }
 
 // DefaultOpt is the default values used for Options
@@ -46,6 +49,7 @@ func Start(opt *Options) {
 // server contains everything to run the server
 type server struct {
 	srv   *httplib.Server
+	files http.Handler
 }
 
 func newServer(opt *Options) *server {
@@ -55,6 +59,17 @@ func newServer(opt *Options) *server {
 		srv: httplib.NewServer(mux, &opt.HTTPOptions),
 	}
 	mux.HandleFunc("/", s.handler)
+
+	// Add some more mime types which are often missing
+	mime.AddExtensionType(".wasm", "application/wasm")
+	mime.AddExtensionType(".js", "application/javascript")
+
+	// File handling
+	s.files = http.NewServeMux()
+	if opt.Files != "" {
+		fs.Logf(nil, "Serving files from %q", opt.Files)
+		s.files = http.FileServer(http.Dir(opt.Files))
+	}
 	return s
 }
 
@@ -65,6 +80,10 @@ func (s *server) serve() {
 		fs.Errorf(nil, "Opening listener: %v", err)
 	}
 	fs.Logf(nil, "Serving remote control on %s", s.srv.URL())
+	// Open the files in the browser if set
+	if s.files != nil {
+		_ = open.Start(s.srv.URL())
+	}
 	s.srv.Wait()
 }
 
@@ -75,65 +94,8 @@ func WriteJSON(w io.Writer, out Params) error {
 	return enc.Encode(out)
 }
 
-// handler reads incoming requests and dispatches them
-func (s *server) handler(w http.ResponseWriter, r *http.Request) {
-	path := strings.Trim(r.URL.Path, "/")
-	in := make(Params)
-
-	writeError := func(err error, status int) {
-		fs.Errorf(nil, "rc: %q: error: %v", path, err)
-		w.WriteHeader(status)
-		err = WriteJSON(w, Params{
-			"error": err.Error(),
-			"input": in,
-		})
-		if err != nil {
-			// can't return the error at this point
-			fs.Errorf(nil, "rc: failed to write JSON output: %v", err)
-		}
-	}
-
-	// Parse the POST and URL parameters into r.Form, for others r.Form will be empty value
-	err := r.ParseForm()
-	if err != nil {
-		writeError(errors.Wrap(err, "failed to parse form/URL parameters"), http.StatusBadRequest)
-		return
-	}
-
-	// Read the POST and URL parameters into in
-	for k, vs := range r.Form {
-		if len(vs) > 0 {
-			in[k] = vs[len(vs)-1]
-		}
-	}
-
-	// Parse a JSON blob from the input
-	if r.Header.Get("Content-Type") == "application/json" {
-		err := json.NewDecoder(r.Body).Decode(&in)
-		if err != nil {
-			writeError(errors.Wrap(err, "failed to read input JSON"), http.StatusBadRequest)
-			return
-		}
-	}
-
-	w.Header().Add("Access-Control-Allow-Origin", "*")
-	//echo back headers client needs
-	reqAccessHeaders := r.Header.Get("Access-Control-Request-Headers")
-	w.Header().Add("Access-Control-Allow-Headers", reqAccessHeaders)
-
-	switch r.Method {
-	case "POST":
-		s.handlePost(w, r, path, in)
-	case "OPTIONS":
-		s.handleOptions(w, r, in)
-	default:
-		writeError(errors.Errorf("method %q not allowed - POST or OPTIONS required", r.Method), http.StatusMethodNotAllowed)
-		return
-	}
-}
-
-func (s *server) handlePost(w http.ResponseWriter, r *http.Request, path string, in Params) {
-	writeError := func(err error, status int) {
+// writeError writes a formatted error to the output
+func writeError(path string, in Params, w http.ResponseWriter, err error, status int) {
 	fs.Errorf(nil, "rc: %q: error: %v", path, err)
 	// Adjust the error return for some well known errors
 	switch errors.Cause(err) {
@@ -151,17 +113,65 @@ func (s *server) handlePost(w http.ResponseWriter, r *http.Request, path string,
 	}
 }
 
+// handler reads incoming requests and dispatches them
+func (s *server) handler(w http.ResponseWriter, r *http.Request) {
+	path := strings.Trim(r.URL.Path, "/")
+
+	w.Header().Add("Access-Control-Allow-Origin", "*")
+
+	// echo back access control headers client needs
+	reqAccessHeaders := r.Header.Get("Access-Control-Request-Headers")
+	w.Header().Add("Access-Control-Allow-Headers", reqAccessHeaders)
+
+	switch r.Method {
+	case "POST":
+		s.handlePost(w, r, path)
+	case "OPTIONS":
+		s.handleOptions(w, r, path)
+	case "GET":
+		s.handleGet(w, r, path)
+	default:
+		writeError(path, nil, w, errors.Errorf("method %q not allowed", r.Method), http.StatusMethodNotAllowed)
+		return
+	}
+}
+
+func (s *server) handlePost(w http.ResponseWriter, r *http.Request, path string) {
+	// Parse the POST and URL parameters into r.Form, for others r.Form will be empty value
+	err := r.ParseForm()
+	if err != nil {
+		writeError(path, nil, w, errors.Wrap(err, "failed to parse form/URL parameters"), http.StatusBadRequest)
+		return
+	}
+
+	// Read the POST and URL parameters into in
+	in := make(Params)
+	for k, vs := range r.Form {
+		if len(vs) > 0 {
+			in[k] = vs[len(vs)-1]
+		}
+	}
+
+	// Parse a JSON blob from the input
+	if r.Header.Get("Content-Type") == "application/json" {
+		err := json.NewDecoder(r.Body).Decode(&in)
+		if err != nil {
+			writeError(path, in, w, errors.Wrap(err, "failed to read input JSON"), http.StatusBadRequest)
+			return
+		}
+	}
+
 	// Find the call
 	call := registry.get(path)
 	if call == nil {
-		writeError(errors.Errorf("couldn't find method %q", path), http.StatusMethodNotAllowed)
+		writeError(path, in, w, errors.Errorf("couldn't find method %q", path), http.StatusMethodNotAllowed)
 		return
 	}
 
 	// Check to see if it is async or not
 	isAsync, err := in.GetBool("_async")
 	if err != nil {
-		writeError(err, http.StatusBadRequest)
+		writeError(path, in, w, err, http.StatusBadRequest)
 		return
 	}
 
@@ -173,7 +183,7 @@ func (s *server) handlePost(w http.ResponseWriter, r *http.Request, path string,
 		out, err = call.Fn(in)
 	}
 	if err != nil {
-		writeError(err, http.StatusInternalServerError)
+		writeError(path, in, w, err, http.StatusInternalServerError)
 		return
 	}
 	if out == nil {
@@ -187,6 +197,15 @@ func (s *server) handlePost(w http.ResponseWriter, r *http.Request, path string,
 		fs.Errorf(nil, "rc: failed to write JSON output: %v", err)
 	}
 }
-func (s *server) handleOptions(w http.ResponseWriter, r *http.Request, in Params) {
+
+func (s *server) handleOptions(w http.ResponseWriter, r *http.Request, path string) {
 	w.WriteHeader(http.StatusOK)
 }
+
+func (s *server) handleGet(w http.ResponseWriter, r *http.Request, path string) {
+	if s.files == nil {
+		w.WriteHeader(http.StatusNotFound)
+		return
+	}
+	s.files.ServeHTTP(w, r)
+}

fs/rc/rcflags/rcflags.go

@@ -16,5 +16,6 @@ var (
 // AddFlags adds the remote control flags to the flagSet
 func AddFlags(flagSet *pflag.FlagSet) {
 	flags.BoolVarP(flagSet, &Opt.Enabled, "rc", "", false, "Enable the remote control server.")
+	flags.StringVarP(flagSet, &Opt.Files, "rc-files", "", "", "Serve these files on the HTTP server.")
 	httpflags.AddFlagsPrefix(flagSet, "rc-", &Opt.HTTPOptions)
 }