Add support for HTTP rate limiting

Closes #16

cmd/stepd/main.go

@@ -51,6 +51,10 @@ func main () {
 		0, "http-directory-document",
 		"The document to use for displaying directory listings over http",
 		"", cli.ValString)
+	flagHTTPRateLimit := cli.NewInputFlag (
+		0, "http-rate-limit",
+		"Seconds an HTTP client must wait per request",
+		"", cli.ValString)
 	flagDirectories := cli.NewFlag (
 		'd', "directories",
 		"Serve the contents of directories")
@@ -149,6 +153,9 @@ func main () {
 	if flagHTTPErrorDocument.Value != "" {
 		config.Set("http.error-document", flagHTTPErrorDocument.Value)
 	}
+	if flagHTTPRateLimit.Value != "" {
+		config.Set("http.rate-limit", flagHTTPRateLimit.Value)
+	}
 	if flagDirectories.Value != "" {
 		config.Set("http.serve-directories", flagDirectories.Value)
 	}
@@ -181,17 +188,25 @@ func main () {
 
 	// initialize the environment
 	err = environment.Init(context.Background())
-	if err != nil { log.Fatal(err) }
+	if err != nil { log.Fatal("XXX:", err) }
 
 	// set up the HTTP handler
+	rateLimit := 0.0
+	if rateLimitStr := config.Get("http.rate-limit"); rateLimitStr != "" {
+		rateLimit, err = strconv.ParseFloat(rateLimitStr, 64)
+		if err != nil { log.Fatal("XXX bad value for rate limit", err) }
+	}
 	handler := stephttp.Handler {
-		Environment:       &environment,
-		Directories:       config.Get("http.serve-directories") == "true",
-		StepExt:           ucontainer.NewSet(slices.Clone(config["http.step-extension"])...),
-		Index:             slices.Clone(config["http.index-file"]),
-		ErrorDocument:     config.Get("http.error-document"),
-		DirectoryDocument: config.Get("http.directory-document"),
-		DenyAll:           ucontainer.NewSet(configFileName),
+		Environment:         &environment,
+		Directories:         config.Get("http.serve-directories") == "true",
+		StepExt:             ucontainer.NewSet(slices.Clone(config["http.step-extension"])...),
+		Index:               slices.Clone(config["http.index-file"]),
+		ErrorDocument:       config.Get("http.error-document"),
+		DirectoryDocument:   config.Get("http.directory-document"),
+		DenyAll:             ucontainer.NewSet(configFileName),
+		RateLimit:           time.Duration(rateLimit * float64(time.Second)),
+		TrustXForwardedFor:  config.Get("http.trust-x-forwarded-for") == "true",
+		TrustCFConnectingIP: config.Get("http.trust-cf-connecting-ip") == "true",
 	}
 	if len(handler.StepExt) == 0 {
 		handler.StepExt.Add(".step")
@@ -199,6 +214,8 @@ func main () {
 	if len(handler.Index) == 0 {
 		handler.Index = []string { "index.step", "index.html", "index" }
 	}
+	err = handler.Init(ctx)
+	if err != nil { log.Println("XXX", err) }
 
 	// set up the HTTP server
 	httpServer := httpServerRoutine {
@@ -206,10 +223,16 @@ func main () {
 		Handler: &handler,
 	}
 
+	// set up the trimming routine
+	trimmer := trimmerRoutine {
+		HTTPHandler: &handler,
+	}
+
 	// set up the routine manager
 	manager := routines.Manager {
 		Routines: []routines.Routine {
 			&httpServer,
+			&trimmer,
 		},
 	}
 	
@@ -242,6 +265,23 @@ func (this *httpServerRoutine) Run (ctx context.Context) error {
 	return err
 }
 
+type trimmerRoutine struct {
+	HTTPHandler *stephttp.Handler
+}
+
+func (this *trimmerRoutine) Run (ctx context.Context) error {
+	ticker := time.NewTicker(1 * time.Minute)
+	defer ticker.Stop()
+	for {
+		select {
+		case <- ticker.C:
+			this.HTTPHandler.Trim()
+		case <- ctx.Done():
+			return ctx.Err()
+		}
+	}
+}
+
 func logProviders (providers []step.Provider) {
 	output := "providers: "
 	x := utf8.RuneCountInString(output)