rounds/redirectHTML.go

   1 /*
   2 tofuproxy -- HTTP proxy with TLS certificates management
   3 Copyright (C) 2021 Sergey Matveev <stargrave@stargrave.org>
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation, version 3 of the License.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 package rounds
  19
  20 import (
  21         "fmt"
  22         "net/http"
  23         "path/filepath"
  24         "strings"
  25
  26         "go.stargrave.org/tofuproxy/fifos"
  27 )
  28
  29 var imageExts = map[string]struct{}{
  30         ".apng": {},
  31         ".avif": {},
  32         ".gif":  {},
  33         ".heic": {},
  34         ".jp2":  {},
  35         ".jpeg": {},
  36         ".jpg":  {},
  37         ".jxl":  {},
  38         ".mng":  {},
  39         ".png":  {},
  40         ".svg":  {},
  41         ".tif":  {},
  42         ".tiff": {},
  43         ".webp": {},
  44 }
  45
  46 func isNewsboat(req *http.Request) bool {
  47         return strings.Contains(req.Header.Get("User-Agent"), "newsboat/")
  48 }
  49
  50 func RoundRedirectHTML(
  51         host string,
  52         resp *http.Response,
  53         w http.ResponseWriter,
  54         req *http.Request,
  55 ) (bool, error) {
  56         if req.Method != http.MethodGet {
  57                 return true, nil
  58         }
  59         var redirType string
  60         switch resp.StatusCode {
  61         case http.StatusMovedPermanently, http.StatusPermanentRedirect:
  62                 redirType = "permanent"
  63         case http.StatusFound, http.StatusSeeOther, http.StatusTemporaryRedirect:
  64                 if isNewsboat(req) {
  65                         return true, nil
  66                 }
  67                 if _, ok := imageExts[filepath.Ext(req.URL.Path)]; ok {
  68                         return true, nil
  69                 }
  70                 redirType = "temporary"
  71         default:
  72                 return true, nil
  73         }
  74         resp.Body.Close()
  75         w.Header().Add("Content-Type", "text/html")
  76         w.WriteHeader(http.StatusOK)
  77         location := resp.Header.Get("Location")
  78         w.Write([]byte(
  79                 fmt.Sprintf(
  80                         `<html><head><title>%d %s: %s redirection</title></head>
  81 <body>Redirection to <a href="%s">%s</a></body></html>`,
  82                         resp.StatusCode, http.StatusText(resp.StatusCode),
  83                         redirType, location, location,
  84                 )))
  85         fifos.LogRedir <- fmt.Sprintf(
  86                 "%s %s\t%s\t%s", req.Method, req.URL, resp.Status, location,
  87         )
  88         return false, nil
  89 }