rounds/redirectHTML.go

   1 // tofuproxy -- flexible HTTP/HTTPS proxy, TLS terminator, X.509 TOFU
   2 //              manager, WARC/geminispace browser
   3 // Copyright (C) 2021-2024 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 package rounds
  18
  19 import (
  20         "fmt"
  21         "net/http"
  22         "path/filepath"
  23         "strings"
  24
  25         "go.stargrave.org/tofuproxy/fifos"
  26 )
  27
  28 var imageExts = map[string]struct{}{
  29         ".apng": {},
  30         ".avif": {},
  31         ".gif":  {},
  32         ".heic": {},
  33         ".jp2":  {},
  34         ".jpeg": {},
  35         ".jpg":  {},
  36         ".jxl":  {},
  37         ".mng":  {},
  38         ".png":  {},
  39         ".svg":  {},
  40         ".tif":  {},
  41         ".tiff": {},
  42         ".webp": {},
  43 }
  44
  45 func isFeeder(req *http.Request) bool {
  46         if strings.Contains(req.Header.Get("User-Agent"), "newsboat/") {
  47                 return true
  48         }
  49         if strings.Contains(req.Header.Get("User-Agent"), "stargrave.org-feeder/") {
  50                 return true
  51         }
  52         return false
  53 }
  54
  55 func RoundRedirectHTML(
  56         host string,
  57         resp *http.Response,
  58         w http.ResponseWriter,
  59         req *http.Request,
  60 ) (bool, error) {
  61         if req.Method != http.MethodGet {
  62                 return true, nil
  63         }
  64         var redirType string
  65         switch resp.StatusCode {
  66         case http.StatusMovedPermanently, http.StatusPermanentRedirect:
  67                 redirType = "permanent"
  68         case http.StatusFound, http.StatusSeeOther, http.StatusTemporaryRedirect:
  69                 if isFeeder(req) {
  70                         return true, nil
  71                 }
  72                 if _, ok := imageExts[filepath.Ext(req.URL.Path)]; ok {
  73                         return true, nil
  74                 }
  75                 redirType = "temporary"
  76         default:
  77                 return true, nil
  78         }
  79         resp.Body.Close()
  80         w.Header().Add("Content-Type", "text/html")
  81         w.WriteHeader(http.StatusOK)
  82         location := resp.Header.Get("Location")
  83         fmt.Fprintf(
  84                 w, `<!DOCTYPE html>
  85 <html><head><title>%d %s: %s redirection</title></head>
  86 <body><a href="%s">%s</a></body></html>`,
  87                 resp.StatusCode, http.StatusText(resp.StatusCode),
  88                 redirType, location, location,
  89         )
  90         fifos.LogRedir <- fmt.Sprintf(
  91                 "%s %s\t%s\t%s", req.Method, req.URL, resp.Status, location,
  92         )
  93         return false, nil
  94 }