// Copyright 2015 Light Code Labs, LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package redirect is middleware for redirecting certain requests
// to other locations.
package redirect
import (
"fmt"
"html"
"net/http"
"github.com/mholt/caddy/caddyhttp/httpserver"
)
// Redirect is middleware to respond with HTTP redirects
type Redirect struct {
Next httpserver.Handler
Rules []Rule
}
// ServeHTTP implements the httpserver.Handler interface.
func (rd Redirect) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
for _, rule := range rd.Rules {
if (rule.FromPath == "/" || r.URL.Path == rule.FromPath) && schemeMatches(rule, r) && rule.Match(r) {
to := httpserver.NewReplacer(r, nil, "").Replace(rule.To)
if rule.Meta {
safeTo := html.EscapeString(to)
fmt.Fprintf(w, metaRedir, safeTo, safeTo)
} else {
http.Redirect(w, r, to, rule.Code)
}
return 0, nil
}
}
return rd.Next.ServeHTTP(w, r)
}
func schemeMatches(rule Rule, req *http.Request) bool {
return (rule.FromScheme() == "https" && req.TLS != nil) ||
(rule.FromScheme() != "https" && req.TLS == nil)
}
// Rule describes an HTTP redirect rule.
type Rule struct {
FromScheme func() string
FromPath, To string
Code int
Meta bool
httpserver.RequestMatcher
}
// Script tag comes first since that will better imitate a redirect in the browser's
// history, but the meta tag is a fallback for most non-JS clients.
const metaRedir = `<!DOCTYPE html>
<html>
<head>
<script>window.location.replace("%s");</script>
<meta http-equiv="refresh" content="0; URL='%s'">
</head>
<body>Redirecting...</body>
</html>
`