Add MUD-Visualizer to page

README.md

@@ -13,6 +13,8 @@ The access control policies described in a MUD File allow network controllers to
 * Improve README.md
 * Add 'Use' to commands
 * Add tests
+* Customize / improve the MUD Visualizer?
+* Add logging (with levels)
 * Replace calls to fmt with proper logging / output
 * Allow the tool to be chained (i.e. use STDIN/STDOUT, pipes, etc.)
 * A command for generating MUD files (from pcap or some different way)

cmd/view.go

@@ -16,14 +16,19 @@ limitations under the License.
 package cmd
 
 import (
+	"context"
 	"log"
 	"net/http"
+	"strconv"
 	"time"
 
 	"github.com/hslatman/mud-cli/internal"
 	"github.com/hslatman/mud-cli/web"
+	"github.com/pkg/browser"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
+
+	"github.com/antage/eventsource"
 )
 
 // viewCmd represents the view command
@@ -44,31 +49,55 @@ var viewCmd = &cobra.Command{
 			return errors.Wrap(err, "getting JSON representation of MUD file failed")
 		}
 
-		// TODO: open browser; show MUD Visualizer with the chosen MUD file
-		// TODO: provide option to show it in terminal?
+		// TODO: provide option to show it in terminal with some ASCII art?
+		// TODO: provide option to show it in a Wails UI (instead of default browser)?
+
+		closeChan := make(chan struct{}, 1)
+		stopChan := make(chan error, 1)
 
 		mudHandler := newMUDHandler(json)
+		streamHandler := newStreamHandler(closeChan)
 
 		// Strip / and prepend build, so that a file `a/b.js` would be
 		// found in web/build/a/b.js, but served from localhost:8080/a/b.js.
 		webHandler := web.AssetHandler("/", "build")
 
 		mux := http.NewServeMux()
 		mux.Handle("/mud", mudHandler)
+		mux.Handle("/heartbeat", streamHandler)
 		mux.Handle("/", webHandler)
 		mux.Handle("/*filepath", webHandler)
 
 		s := &http.Server{
-			Addr:           ":8080",
+			Addr:           "localhost:8080",
 			Handler:        mux,
 			ReadTimeout:    10 * time.Second,
 			WriteTimeout:   10 * time.Second,
 			MaxHeaderBytes: 1 << 20,
 		}
 
-		log.Fatal(s.ListenAndServe()) // TODO: add some logging?
+		s.RegisterOnShutdown(streamHandler.Close)
+
+		go func() {
+			<-closeChan
+			log.Println("closing server ...")
+			ctx := context.Background()
+			ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
+			defer cancel()
+			stopChan <- s.Shutdown(ctx)
+		}()
+
+		// TODO: add some more logging?
+
+		log.Println("serving at ...")
+		go s.ListenAndServe()
+
+		log.Println("go to ...")
+		go browser.OpenURL("http://localhost:8080/")
 
-		return nil
+		err = <-stopChan
+
+		return err
 	},
 }
 
@@ -86,6 +115,65 @@ func newMUDHandler(json string) http.Handler {
 	}
 }
 
+type streamHandler struct {
+	es eventsource.EventSource
+	c  chan struct{}
+}
+
+func newStreamHandler(c chan struct{}) *streamHandler {
+	es := eventsource.New(
+		&eventsource.Settings{
+			Timeout:        2 * time.Second,
+			CloseOnTimeout: true,
+			IdleTimeout:    2 * time.Second,
+			Gzip:           true,
+		},
+		func(req *http.Request) [][]byte {
+			return [][]byte{
+				[]byte("X-Accel-Buffering: no"),
+				[]byte("Access-Control-Allow-Origin: *"),
+			}
+		},
+	)
+	return &streamHandler{
+		es: es,
+		c:  c,
+	}
+}
+
+func (s *streamHandler) Close() {
+	s.es.Close()
+}
+
+func (s *streamHandler) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
+
+	numberOfConsumers := s.es.ConsumersCount()
+
+	// serve sse to the (new) connection
+	s.es.ServeHTTP(resp, req)
+
+	// the routine for pings should only be started once
+	if numberOfConsumers > 0 {
+		return
+	}
+
+	// send a ping to all consumers every second
+	go func() {
+		var id int
+		for {
+			id++
+			time.Sleep(1 * time.Second)
+			s.es.SendEventMessage("ping", "message", strconv.Itoa(id))
+			// break out of the loop when 0 consumers are reached again
+			if s.es.ConsumersCount() == 0 {
+				break
+			}
+		}
+		s.c <- struct{}{}
+	}()
+
+}
+
 func init() {
 	rootCmd.AddCommand(viewCmd)
 }

go.mod

@@ -3,9 +3,11 @@ module github.com/hslatman/mud-cli
 go 1.16
 
 require (
+	github.com/antage/eventsource v0.0.0-20190412115600-84b661236871
 	github.com/github/ietf-cms v0.1.0
 	github.com/hslatman/mud.yang.go v0.0.0-20201016091044-991f3fbb23d0
 	github.com/openconfig/ygot v0.11.2
+	github.com/pkg/browser v0.0.0-20210706143420-7d21f8c997e2
 	github.com/pkg/errors v0.9.1
 	github.com/spf13/cobra v1.2.1
 	go.step.sm/crypto v0.9.0

go.sum

@@ -45,6 +45,8 @@ github.com/Masterminds/sprig/v3 v3.1.0/go.mod h1:ONGMf7UfYGAbMXCZmQLy8x3lCDIPrEZ
 github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
 github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
+github.com/antage/eventsource v0.0.0-20190412115600-84b661236871 h1:CU/EFaNIixooGaewG9cX4BShXURU/ejdC/r0Ly0jESo=
+github.com/antage/eventsource v0.0.0-20190412115600-84b661236871/go.mod h1:WOB/cuaphqWnO64ntuJ3CbpM+kDsKaQp1aeIB4AuXGI=
 github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
 github.com/armon/circbuf v0.0.0-20150827004946-bbbad097214e/go.mod h1:3U/XgcO3hCbHZ8TKRvWD2dDTCfh9M9ya+I9JpbB7O8o=
 github.com/armon/consul-api v0.0.0-20180202201655-eb2c6b5be1b6/go.mod h1:grANhF5doyWs3UAsr3K4I6qtAmlQcZDesFNEHPZAzj8=
@@ -262,6 +264,8 @@ github.com/pborman/getopt v0.0.0-20190409184431-ee0cd42419d3/go.mod h1:85jBQOZwp
 github.com/pborman/getopt v1.1.0/go.mod h1:FxXoW1Re00sQG/+KIkuSqRL/LwQgSkv7uyac+STFsbk=
 github.com/pelletier/go-toml v1.2.0/go.mod h1:5z9KED0ma1S8pY6P1sdut58dfprrGBbd/94hg7ilaic=
 github.com/pelletier/go-toml v1.9.3/go.mod h1:u1nR/EPcESfeI/szUZKdtJ0xRNbUoANCkoOuaOx1Y+c=
+github.com/pkg/browser v0.0.0-20210706143420-7d21f8c997e2 h1:acNfDZXmm28D2Yg/c3ALnZStzNaZMSagpbr96vY6Zjc=
+github.com/pkg/browser v0.0.0-20210706143420-7d21f8c997e2/go.mod h1:HKlIX3XHQyzLZPlr7++PzdhaXEj94dEiJgZDTsxEqUI=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
@@ -502,8 +506,9 @@ golang.org/x/sys v0.0.0-20210315160823-c6e025ad8005/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210320140829-1e4c9ba3b0c4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210403161142-5e06dd20ab57/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210510120138-977fb7262007 h1:gG67DSER+11cZvqIMb8S8bt0vZtiN6xWYARwirrOSfE=
 golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20210616045830-e2b7044e8c71 h1:X/2sJAybVknnUnV7AD2HdT6rm2p5BP6eH2j+igduWgk=
+golang.org/x/sys v0.0.0-20210616045830-e2b7044e8c71/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=