Add DomainRedirectHandler

domain_redirect.go

@@ -0,0 +1,68 @@
+// Copyright (c) 2016, Janoš Guljaš <[email protected]>
+// All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package web
+
+import (
+	"net"
+	"net/http"
+	"strconv"
+	"strings"
+)
+
+// DomainRedirectHandler responds with redirect url based on
+// domain and httpsPort, othervise it executes the handler.
+func DomainRedirectHandler(h http.Handler, domain, httpsPort string) http.Handler {
+	if domain == "" && httpsPort == "" {
+		return h
+	}
+
+	scheme := "http"
+	port := ""
+	if httpsPort != "" {
+		if _, err := strconv.Atoi(httpsPort); err == nil {
+			scheme = "https"
+			port = httpsPort
+		}
+		if _, p, err := net.SplitHostPort(httpsPort); err == nil {
+			scheme = "https"
+			port = p
+		}
+	}
+	if port == "443" {
+		port = ""
+	}
+	var altDomain string
+	if strings.HasPrefix("www.", domain) {
+		altDomain = strings.TrimPrefix(domain, "www.")
+	} else {
+		altDomain = "www." + domain
+	}
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		d, p, err := net.SplitHostPort(r.Host)
+		if err != nil {
+			d = r.Host
+		}
+		if d == domain && r.URL.Scheme == scheme {
+			h.ServeHTTP(w, r)
+			return
+		}
+		switch {
+		case scheme == "http" && p == "80":
+			p = ""
+		case scheme == "https" && p == "443":
+			p = ""
+		case port != "":
+			p = ":" + port
+		default:
+			p = ":" + p
+		}
+		if d == altDomain {
+			http.Redirect(w, r, strings.Join([]string{scheme, "://", domain, p, r.RequestURI}, ""), http.StatusMovedPermanently)
+			return
+		}
+		http.Redirect(w, r, strings.Join([]string{scheme, "://", domain, p, r.RequestURI}, ""), http.StatusFound)
+	})
+}