From c60c40c65d2e19531c047ca2736f3206199249a8 Mon Sep 17 00:00:00 2001
From: Oleg Gordienko <admin@gordio.pp.ua>
Date: Wed, 28 Sep 2016 16:28:27 +0000
Subject: [PATCH] Check that client can accept gzip, check if '.gz' file exist
 and serve it.

---
 domain.go | 58 +++++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 48 insertions(+), 10 deletions(-)

diff --git a/domain.go b/domain.go
index 46f57ed02..ce92c2834 100644
--- a/domain.go
+++ b/domain.go
@@ -22,12 +22,31 @@ type domain struct {
 }
 
 func (d *domain) serveFile(w http.ResponseWriter, r *http.Request, fullPath string) error {
-	// Open and serve content of file
-	file, err := os.Open(fullPath)
-	if err != nil {
-		return err
+	// gzipped file exist and readable
+	file, err := os.Open(fullPath + ".gz")
+	if err == nil {
+		defer file.Close()
+
+		// Client accept gzip
+		if strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
+			// Add response header about compression
+			w.Header().Set("Content-Encoding", "gzip")
+		} else {
+			// Open and serve content of file
+			file, err := os.Open(fullPath)
+			if err != nil {
+				return err
+			}
+			defer file.Close()
+		}
+	} else {
+		// Open and serve content of file
+		file, err := os.Open(fullPath)
+		if err != nil {
+			return err
+		}
+		defer file.Close()
 	}
-	defer file.Close()
 
 	fi, err := file.Stat()
 	if err != nil {
@@ -40,12 +59,31 @@ func (d *domain) serveFile(w http.ResponseWriter, r *http.Request, fullPath stri
 }
 
 func (d *domain) serveCustomFile(w http.ResponseWriter, r *http.Request, code int, fullPath string) error {
-	// Open and serve content of file
-	file, err := os.Open(fullPath)
-	if err != nil {
-		return err
+	// gzipped file exist and readable
+	file, err := os.Open(fullPath + ".gz")
+	if err == nil {
+		defer file.Close()
+
+		// Client accept gzip
+		if strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
+			// Add response header about compression
+			w.Header().Set("Content-Encoding", "gzip")
+		} else {
+			// Open and serve content of file
+			file, err := os.Open(fullPath)
+			if err != nil {
+				return err
+			}
+			defer file.Close()
+		}
+	} else {
+		// Open and serve content of file
+		file, err := os.Open(fullPath)
+		if err != nil {
+			return err
+		}
+		defer file.Close()
 	}
-	defer file.Close()
 
 	fi, err := file.Stat()
 	if err != nil {
-- 
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