rewrite middleware: add subdomain redirect example

_examples/routing/rewrite/hosts

@@ -1,3 +1,4 @@
 127.0.0.1	mydomain.com
 127.0.0.1	www.mydomain.com
-127.0.0.1	test.mydomain.com
+127.0.0.1	test.mydomain.com
+127.0.0.1	newtest.mydomain.com

_examples/routing/rewrite/main.go

@@ -13,17 +13,22 @@ func main() {
 
 	app.Subdomain("test").Get("/", testIndex)
 
+	newtest := app.Subdomain("newtest")
+	newtest.Get("/", newTestIndex)
+	newtest.Get("/", newTestAbout)
+
 	redirects := rewrite.Load("redirects.yml")
 	app.WrapRouter(redirects)
 
-	// http://mydomain.com:8080/seo/about     -> http://www.mydomain.com:8080/about
+	// http://mydomain.com:8080/seo/about      -> http://www.mydomain.com:8080/about
-	// http://test.mydomain.com:8080
+	// http://test.mydomain.com:8080           -> http://newtest.mydomain.com:8080
-	// http://localhost:8080/seo              -> http://localhost:8080
+	// http://test.mydomain.com:8080/seo/about -> http://newtest.mydomain.com:8080/about
+	// http://localhost:8080/seo               -> http://localhost:8080
 	// http://localhost:8080/about
-	// http://localhost:8080/docs/v12/hello   -> http://localhost:8080/docs
+	// http://localhost:8080/docs/v12/hello    -> http://localhost:8080/docs
-	// http://localhost:8080/docs/v12some     -> http://localhost:8080/docs
+	// http://localhost:8080/docs/v12some      -> http://localhost:8080/docs
-	// http://localhost:8080/oldsome          -> http://localhost:8080
+	// http://localhost:8080/oldsome           -> http://localhost:8080
-	// http://localhost:8080/oldindex/random  -> http://localhost:8080
+	// http://localhost:8080/oldindex/random   -> http://localhost:8080
 	app.Listen(":8080")
 }
 
@@ -40,7 +45,15 @@ func docs(ctx iris.Context) {
 }
 
 func testIndex(ctx iris.Context) {
-	ctx.WriteString("Test Subdomain Index")
+	ctx.WriteString("Test Subdomain Index (This should never be executed, redirects to newtest subdomain)")
+}
+
+func newTestIndex(ctx iris.Context) {
+	ctx.WriteString("New Test Subdomain Index")
+}
+
+func newTestAbout(ctx iris.Context) {
+	ctx.WriteString("New Test Subdomain About")
 }
 
 /* More...
@@ -49,6 +62,7 @@ rewriteOptions := rewrite.Options{
 		"301 /seo/(.*) /$1",
 		"301 /docs/v12(.*) /docs",
 		"301 /old(.*) /",
+		"301 ^(http|https)://test.(.*) $1://newtest.$2",
 	},
 	PrimarySubdomain: "www",
 }

_examples/routing/rewrite/redirects.yml

@@ -6,5 +6,7 @@ RedirectMatch:
   - 301 /docs/v12(.*) /docs
     # redirects /old(.*) to /
   - 301 /old(.*) /
+    # redirects http or https://test.* to http or https://newtest.*
+  - 301 ^(http|https)://test.(.*) $1://newtest.$2
 # redirects root domain to www.
 PrimarySubdomain: www

middleware/rewrite/rewrite.go

@@ -8,6 +8,7 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+	"text/template"
 
 	"github.com/kataras/iris/v12/context"
 	"github.com/kataras/iris/v12/core/router"
@@ -176,7 +177,8 @@ func (e *Engine) Rewrite(w http.ResponseWriter, r *http.Request, routeHandler ht
 	for _, rd := range e.redirects {
 		src := r.URL.Path
 		if !rd.isRelativePattern {
-			src = r.URL.String()
+			// don't change the request, use a full redirect.
+			src = context.GetScheme(r) + context.GetHost(r) + r.URL.RequestURI()
 		}
 
 		if target, ok := rd.matchAndReplace(src); ok {
@@ -185,7 +187,14 @@ func (e *Engine) Rewrite(w http.ResponseWriter, r *http.Request, routeHandler ht
 				return
 			}
 
-			http.Redirect(w, r, target, rd.code)
+			if !rd.isRelativePattern {
+				// this performs better, no need to check query or host,
+				// the uri already built.
+				redirectAbs(w, r, target, rd.code)
+			} else {
+				http.Redirect(w, r, target, rd.code)
+			}
+
 			return
 		}
 	}
@@ -263,3 +272,22 @@ func getPort(hostport string) string { // returns :port, note that this is only
 
 	return ""
 }
+
+func redirectAbs(w http.ResponseWriter, r *http.Request, url string, code int) {
+	// part of net/http std library.
+	h := w.Header()
+
+	_, hadCT := h[context.ContentTypeHeaderKey]
+
+	h.Set("Location", url)
+	if !hadCT && (r.Method == http.MethodGet || r.Method == http.MethodHead) {
+		h.Set(context.ContentTypeHeaderKey, "text/html; charset=utf-8")
+	}
+	w.WriteHeader(code)
+
+	// Shouldn't send the body for POST or HEAD; that leaves GET.
+	if !hadCT && r.Method == "GET" {
+		body := "<a href=\"" + template.HTMLEscapeString(url) + "\">" + http.StatusText(code) + "</a>.\n"
+		fmt.Fprintln(w, body)
+	}
+}