rounds/redirectHTML.go

   1 /*
   2 tofuproxy -- flexible HTTP/HTTPS proxy, TLS terminator, X.509 TOFU
   3              manager, WARC/geminispace browser
   4 Copyright (C) 2021-2023 Sergey Matveev <stargrave@stargrave.org>
   5
   6 This program is free software: you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation, version 3 of the License.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19 package rounds
  20
  21 import (
  22         "fmt"
  23         "net/http"
  24         "path/filepath"
  25         "strings"
  26
  27         "go.stargrave.org/tofuproxy/fifos"
  28 )
  29
  30 var imageExts = map[string]struct{}{
  31         ".apng": {},
  32         ".avif": {},
  33         ".gif":  {},
  34         ".heic": {},
  35         ".jp2":  {},
  36         ".jpeg": {},
  37         ".jpg":  {},
  38         ".jxl":  {},
  39         ".mng":  {},
  40         ".png":  {},
  41         ".svg":  {},
  42         ".tif":  {},
  43         ".tiff": {},
  44         ".webp": {},
  45 }
  46
  47 func isFeeder(req *http.Request) bool {
  48         if strings.Contains(req.Header.Get("User-Agent"), "newsboat/") {
  49                 return true
  50         }
  51         if strings.Contains(req.Header.Get("User-Agent"), "stargrave.org-feeder/") {
  52                 return true
  53         }
  54         return false
  55 }
  56
  57 func RoundRedirectHTML(
  58         host string,
  59         resp *http.Response,
  60         w http.ResponseWriter,
  61         req *http.Request,
  62 ) (bool, error) {
  63         if req.Method != http.MethodGet {
  64                 return true, nil
  65         }
  66         var redirType string
  67         switch resp.StatusCode {
  68         case http.StatusMovedPermanently, http.StatusPermanentRedirect:
  69                 redirType = "permanent"
  70         case http.StatusFound, http.StatusSeeOther, http.StatusTemporaryRedirect:
  71                 if isFeeder(req) {
  72                         return true, nil
  73                 }
  74                 if _, ok := imageExts[filepath.Ext(req.URL.Path)]; ok {
  75                         return true, nil
  76                 }
  77                 redirType = "temporary"
  78         default:
  79                 return true, nil
  80         }
  81         resp.Body.Close()
  82         w.Header().Add("Content-Type", "text/html")
  83         w.WriteHeader(http.StatusOK)
  84         location := resp.Header.Get("Location")
  85         fmt.Fprintf(
  86                 w, `<!DOCTYPE html>
  87 <html><head><title>%d %s: %s redirection</title></head>
  88 <body><a href="%s">%s</a></body></html>`,
  89                 resp.StatusCode, http.StatusText(resp.StatusCode),
  90                 redirType, location, location,
  91         )
  92         fifos.LogRedir <- fmt.Sprintf(
  93                 "%s %s\t%s\t%s", req.Method, req.URL, resp.Status, location,
  94         )
  95         return false, nil
  96 }