gzip: Make it gzip again

config/setup/gzip.go

@@ -31,7 +31,7 @@ func gzipParse(c *Controller) ([]gzip.Config, error) {
 		mimeFilter := gzip.MIMEFilter{make(gzip.Set)}
 		extFilter := gzip.ExtFilter{make(gzip.Set)}
 
-		// no extra args expected
+		// No extra args expected
 		if len(c.RemainingArgs()) > 0 {
 			return configs, c.ArgErr()
 		}
@@ -45,7 +45,7 @@ func gzipParse(c *Controller) ([]gzip.Config, error) {
 				}
 				for _, m := range mimes {
 					if !gzip.ValidMIME(m) {
-						return configs, fmt.Errorf("Invalid MIME %v.", m)
+						return configs, fmt.Errorf("gzip: invalid MIME %v", m)
 					}
 					mimeFilter.Types.Add(m)
 				}
@@ -56,7 +56,7 @@ func gzipParse(c *Controller) ([]gzip.Config, error) {
 				}
 				for _, e := range exts {
 					if !strings.HasPrefix(e, ".") {
-						return configs, fmt.Errorf(`Invalid extension %v. Should start with "."`, e)
+						return configs, fmt.Errorf(`gzip: invalid extension "%v" (must start with dot)`, e)
 					}
 					extFilter.Exts.Add(e)
 				}
@@ -66,14 +66,13 @@ func gzipParse(c *Controller) ([]gzip.Config, error) {
 					return configs, c.ArgErr()
 				}
 				for _, p := range paths {
+					if p == "/" {
+						return configs, fmt.Errorf(`gzip: cannot exclude path "/" - remove directive entirely instead`)
+					}
 					if !strings.HasPrefix(p, "/") {
-						return configs, fmt.Errorf(`Invalid path %v. Should start with "/"`, p)
+						return configs, fmt.Errorf(`gzip: invalid path "%v" (must start with /)`, p)
 					}
 					pathFilter.IgnoredPaths.Add(p)
-					// Warn user if / is used
-					if p == "/" {
-						fmt.Println("Warning: Paths ignored by gzip includes wildcard(/). No request will be gzipped.\nRemoving gzip directive from Caddyfile is preferred if this is intended.")
-					}
 				}
 			case "level":
 				if !c.NextArg() {
@@ -88,22 +87,20 @@ func gzipParse(c *Controller) ([]gzip.Config, error) {
 
 		config.Filters = []gzip.Filter{}
 
-		// if ignored paths are specified, put in front to filter with path first
+		// If ignored paths are specified, put in front to filter with path first
 		if len(pathFilter.IgnoredPaths) > 0 {
 			config.Filters = []gzip.Filter{pathFilter}
 		}
 
-		// if mime types are specified, use it and ignore extensions
-		if len(mimeFilter.Types) > 0 {
-			config.Filters = append(config.Filters, mimeFilter)
-
-			// if extensions are specified, use it
-		} else if len(extFilter.Exts) > 0 {
+		// If extensions specified, use it over MIME types (if any).
+		// Otherwise, if specified, use MIME types.
+		// Otherwise, use default extensions filter.
+		if len(extFilter.Exts) > 0 {
 			config.Filters = append(config.Filters, extFilter)
-
-			// neither is specified, use default mime types
+		} else if len(mimeFilter.Types) > 0 {
+			config.Filters = append(config.Filters, mimeFilter)
 		} else {
-			config.Filters = append(config.Filters, gzip.DefaultMIMEFilter())
+			config.Filters = append(config.Filters, gzip.DefaultExtFilter())
 		}
 
 		configs = append(configs, config)

middleware/gzip/filter.go

@@ -15,6 +15,18 @@ type Filter interface {
 	ShouldCompress(*http.Request) bool
 }
 
+// defaultExtensions is the list of default extensions for which to enable gzipping.
+var defaultExtensions = []string{"", ".txt", ".html", ".css", ".json", ".js", ".md", ".xml"}
+
+// DefaultExtFilter creates an ExtFilter with default extensions.
+func DefaultExtFilter() ExtFilter {
+	m := ExtFilter{Exts: make(Set)}
+	for _, extension := range defaultExtensions {
+		m.Exts.Add(extension)
+	}
+	return m
+}
+
 // ExtFilter is Filter for file name extensions.
 type ExtFilter struct {
 	// Exts is the file name extensions to accept
@@ -72,7 +84,7 @@ func DefaultMIMEFilter() MIMEFilter {
 // matches any of the registered ones. It returns true if
 // found and false otherwise.
 func (m MIMEFilter) ShouldCompress(r *http.Request) bool {
-	return m.Types.Contains(r.Header.Get("Content-Type"))
+	return m.Types.Contains(r.Header.Get("Accept"))
 }
 
 func ValidMIME(mime string) bool {

middleware/gzip/gzip.go

@@ -36,8 +36,7 @@ func (g Gzip) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
 outer:
 	for _, c := range g.Configs {
 
-		// Check filters to determine if gzipping is permitted for this
-		// request
+		// Check filters to determine if gzipping is permitted for this request
 		for _, filter := range c.Filters {
 			if !filter.ShouldCompress(r) {
 				continue outer