Update caching logic/headers (#184)

* Improve caching by adding etags and reducing the max-age

* Move caching into middleware. Set cache headers on segments

controllers/index.go

@@ -37,21 +37,29 @@ func IndexHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// For search engine bots and social scrapers return a special
+	// server-rendered page.
 	if utils.IsUserAgentABot(r.UserAgent()) && isIndexRequest {
 		handleScraperMetadataPage(w, r)
 		return
 	}
 
+	// If the ETags match then return a StatusNotModified
+	if responseCode := middleware.ProcessEtags(w, r); responseCode != 0 {
+		w.WriteHeader(responseCode)
+		return
+	}
+
 	if path.Ext(r.URL.Path) == ".m3u8" {
 		middleware.DisableCache(w)
 
 		clientID := utils.GenerateClientIDFromRequest(r)
 		core.SetClientActive(clientID)
-	} else {
-		// Set a cache control header of one day
-		middleware.SetCache(1, w)
 	}
 
+	// Set a cache control max-age header
+	middleware.SetCachingHeaders(w, r)
+
 	http.ServeFile(w, r, path.Join("webroot", r.URL.Path))
 }
 

go.mod

@@ -4,6 +4,7 @@ go 1.14
 
 require (
 	github.com/StackExchange/wmi v0.0.0-20190523213315-cbe66965904d // indirect
+	github.com/amalfra/etag v0.0.0-20190921100247-cafc8de96bc5
 	github.com/aws/aws-sdk-go v1.34.0
 	github.com/go-ole/go-ole v1.2.4 // indirect
 	github.com/mattn/go-sqlite3 v1.14.0

go.sum

@@ -1,6 +1,8 @@
 github.com/PuerkitoBio/goquery v1.5.1/go.mod h1:GsLWisAFVj4WgDibEWF4pvYnkVQBpKBKeU+7zCJoLcc=
 github.com/StackExchange/wmi v0.0.0-20190523213315-cbe66965904d h1:G0m3OIz70MZUWq3EgK3CesDbo8upS2Vm9/P3FtgI+Jk=
 github.com/StackExchange/wmi v0.0.0-20190523213315-cbe66965904d/go.mod h1:3eOhrUMpNV+6aFIbp5/iudMxNCF27Vw2OZgy4xEx0Fg=
+github.com/amalfra/etag v0.0.0-20190921100247-cafc8de96bc5 h1:+ty4KYpIDUhjzsVsV+HiTeYEfufBc/4FLNiqIGU1A1U=
+github.com/amalfra/etag v0.0.0-20190921100247-cafc8de96bc5/go.mod h1:Qk51jPgvIaO549MR+IvLP/uMZbZGs05QJSzEhDVZ1jc=
 github.com/andybalholm/cascadia v1.1.0/go.mod h1:GsXiBklL0woXo1j/WYWtSYYC4ouU9PqHO0sqidkEA4Y=
 github.com/aws/aws-sdk-go v1.34.0 h1:brux2dRrlwCF5JhTL7MUT3WUwo9zfDHZZp3+g3Mvlmo=
 github.com/aws/aws-sdk-go v1.34.0/go.mod h1:5zCpMtNQVjRREroY7sYe8lOMRSxkhG6MZveU8YkpAk0=

router/middleware/caching.go

@@ -0,0 +1,64 @@
+package middleware
+
+import (
+	"net/http"
+	"os"
+	"path"
+	"path/filepath"
+	"strconv"
+
+	"github.com/amalfra/etag"
+)
+
+//DisableCache writes the disable cache header on the responses
+func DisableCache(w http.ResponseWriter) {
+	w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
+	w.Header().Set("Expires", "Thu, 1 Jan 1970 00:00:00 GMT")
+}
+
+func setCacheSeconds(seconds int, w http.ResponseWriter) {
+	secondsStr := strconv.Itoa(seconds)
+	w.Header().Set("Cache-Control", "public, max-age="+secondsStr)
+}
+
+// ProcessEtags gets and sets ETags for caching purposes
+func ProcessEtags(w http.ResponseWriter, r *http.Request) int {
+	info, err := os.Stat(filepath.Join("webroot", r.URL.Path))
+	if err != nil {
+		return 0
+	}
+
+	localContentEtag := etag.Generate(info.ModTime().String(), true)
+	if remoteEtagHeader := r.Header.Get("If-None-Match"); remoteEtagHeader != "" {
+		if remoteEtagHeader == localContentEtag {
+			return http.StatusNotModified
+		}
+	}
+
+	w.Header().Set("Etag", localContentEtag)
+
+	return 0
+}
+
+// SetCachingHeaders will set the cache control header of a response
+func SetCachingHeaders(w http.ResponseWriter, r *http.Request) {
+	setCacheSeconds(getCacheDurationSecondsForPath(r.URL.Path), w)
+}
+
+func getCacheDurationSecondsForPath(filePath string) int {
+	if path.Base(filePath) == "thumbnail.jpg" {
+		// Thumbnails re-generate during live
+		return 20
+	} else if path.Ext(filePath) == ".js" || path.Ext(filePath) == ".css" {
+		// Cache javascript & CSS
+		return 60
+	} else if path.Ext(filePath) == ".ts" {
+		// Cache video segments as long as you want. They can't change.
+		// This matters most for local hosting of segments for recordings
+		// and not for live or 3rd party storage.
+		return 31557600
+	}
+
+	// Default cache length in seconds
+	return 30 * 60
+}

router/middleware/disableCache.go

@@ -1,19 +0,0 @@
-package middleware
-
-import (
-	"net/http"
-	"strconv"
-)
-
-//DisableCache writes the disable cache header on the responses
-func DisableCache(w http.ResponseWriter) {
-	w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
-	w.Header().Set("Expires", "0")
-}
-
-//SetCache will set the cache control header of a response
-func SetCache(days int, w http.ResponseWriter) {
-	seconds := strconv.Itoa(days * 86400)
-	w.Header().Set("Cache-Control", "max-age="+seconds)
-	w.Header().Set("Expires", seconds)
-}