Rename to StyleSheet and precache CSS bytes

If there is a custom CSS file specified and usable (it exists and is
readable), we precache it on server startup (for every host). This
increase the request performance and reduce IO-load slightly.

CONFIGURATION.md

@@ -81,9 +81,9 @@ Set this option to `true` to disable this feature.
 
 Pages are converted automatically by [gmitohtml](https://code.rocketnine.space/tslocum/gmitohtml).
 
-## Styles
+## StyleSheet
 
-Specify a custom CSS styles file if you want to override the default. This only
+Specify a custom CSS stylesheet file if you want to override the default. This only
 affects the `HTTPS` protocol (obviously).
 
 ### DisableSize
@@ -228,7 +228,7 @@ hosts:
   gemini.rocks:
     cert: /srv/gemini.rocks/data/cert.crt
     key: /srv/gemini.rocks/data/cert.key
-    styles: /srv/gemini.rocks/styles.css # Custom CSS styles
+    stylesheet: /srv/gemini.rocks/styles.css # Custom CSS stylesheet
     paths:
       -
         path: ^/.*\.php$

config.go

@@ -67,7 +67,7 @@ type hostConfig struct {
 	Paths []*pathConfig
 
 	// Custom CSS styles. If specified, it will be used for all paths in that host/domain.
-	Styles string
+	StyleSheet string
 
 	cert *tls.Certificate
 }
@@ -87,6 +87,8 @@ type serverConfig struct {
 
 const cacheUnset = -1965
 
+var customCSS = make(map[string][]byte)
+
 var config *serverConfig
 
 func readconfig(configPath string) error {
@@ -213,6 +215,21 @@ func readconfig(configPath string) error {
 		}
 		host.cert = &cert
 
+		// Custom CSS stylesheets are precached in customCSS and used on HTTPS requests.
+		if host.StyleSheet != "" {
+			_, err := os.Stat(host.StyleSheet)
+			if os.IsNotExist(err) {
+				log.Printf("custom stylesheet '%v' not found, ignore it.", host.StyleSheet)
+			} else {
+				cssBytes, err := ioutil.ReadFile(host.StyleSheet)
+				if err != nil {
+					log.Printf("problems with stylesheet '%v': %v", host.StyleSheet, err.Error())
+				} else {
+					customCSS[hostname] = cssBytes
+				}
+			}
+		}
+
 		for _, serve := range host.Paths {
 			if serve.Path == "" {
 				log.Fatal("a path must be specified in each serve entry")

serve_https.go

@@ -31,22 +31,6 @@ func serveHTTPS(w http.ResponseWriter, r *http.Request) (int, int64, string) {
 		http.Redirect(w, r, u.String(), status)
 		return status, -1, ""
 	} else if r.URL.Path == "/assets/style.css" {
-		// Do we have a custom CSS file? If so, we use this instead.
-		styleFilepath := config.Hosts[r.URL.Hostname()].Styles
-		if styleFilepath != "" {
-			_, err := os.Stat(styleFilepath)
-			if os.IsNotExist(err) {
-				http.Error(w, "Custom styles not found", http.StatusNotFound)
-				return http.StatusNotFound, -1, ""
-			}
-
-			cssBytes, err = ioutil.ReadFile(styleFilepath)
-			if err != nil {
-				http.Error(w, "Cannot process custom styles", http.StatusInternalServerError)
-				return http.StatusInternalServerError, -1, ""
-			}
-		}
-
 		status := http.StatusOK
 		w.Header().Set("Content-Type", cssType)
 		w.WriteHeader(status)
@@ -55,6 +39,13 @@ func serveHTTPS(w http.ResponseWriter, r *http.Request) (int, int64, string) {
 			return status, 0, ""
 		}
 
+		// Do we have a custom CSS file? If so, we use this instead.
+		if css, found := customCSS[r.URL.Hostname()]; found {
+				w.Write(css)
+				return status, int64(len(css)), ""
+		}
+
+		// Default CSS
 		w.Write(cssBytes)
 		return status, int64(len(cssBytes)), ""
 	}