88 lines
2.7 KiB
Go
88 lines
2.7 KiB
Go
// Copyright 2011 Dmitry Chestnykh. All rights reserved.
|
|
// Use of this source code is governed by a MIT-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package captcha
|
|
|
|
import (
|
|
"bytes"
|
|
"net/http"
|
|
"path"
|
|
"strings"
|
|
"time"
|
|
)
|
|
|
|
type captchaHandler struct {
|
|
imgWidth int
|
|
imgHeight int
|
|
}
|
|
|
|
// Server returns a handler that serves HTTP requests with image or
|
|
// audio representations of captchas. Image dimensions are accepted as
|
|
// arguments. The server decides which captcha to serve based on the last URL
|
|
// path component: file name part must contain a captcha id, file extension —
|
|
// its format (PNG or WAV).
|
|
//
|
|
// For example, for file name "LBm5vMjHDtdUfaWYXiQX.png" it serves an image captcha
|
|
// with id "LBm5vMjHDtdUfaWYXiQX", and for "LBm5vMjHDtdUfaWYXiQX.wav" it serves the
|
|
// same captcha in audio format.
|
|
//
|
|
// To serve a captcha as a downloadable file, the URL must be constructed in
|
|
// such a way as if the file to serve is in the "download" subdirectory:
|
|
// "/download/LBm5vMjHDtdUfaWYXiQX.wav".
|
|
//
|
|
// To reload captcha (get a different solution for the same captcha id), append
|
|
// "?reload=x" to URL, where x may be anything (for example, current time or a
|
|
// random number to make browsers refetch an image instead of loading it from
|
|
// cache).
|
|
//
|
|
// By default, the Server serves audio in English language. To serve audio
|
|
// captcha in one of the other supported languages, append "lang" value, for
|
|
// example, "?lang=ru".
|
|
func Server(imgWidth, imgHeight int) http.Handler {
|
|
return &captchaHandler{imgWidth, imgHeight}
|
|
}
|
|
|
|
func (h *captchaHandler) serve(w http.ResponseWriter, r *http.Request, id, ext, lang string, download bool) error {
|
|
w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
|
|
w.Header().Set("Pragma", "no-cache")
|
|
w.Header().Set("Expires", "0")
|
|
|
|
var content bytes.Buffer
|
|
switch ext {
|
|
case ".png":
|
|
w.Header().Set("Content-Type", "image/png")
|
|
WriteImage(&content, id, h.imgWidth, h.imgHeight)
|
|
case ".wav":
|
|
w.Header().Set("Content-Type", "audio/x-wav")
|
|
WriteAudio(&content, id, lang)
|
|
default:
|
|
return ErrNotFound
|
|
}
|
|
|
|
if download {
|
|
w.Header().Set("Content-Type", "application/octet-stream")
|
|
}
|
|
http.ServeContent(w, r, id+ext, time.Time{}, bytes.NewReader(content.Bytes()))
|
|
return nil
|
|
}
|
|
|
|
func (h *captchaHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
|
|
dir, file := path.Split(r.URL.Path)
|
|
ext := path.Ext(file)
|
|
id := file[:len(file)-len(ext)]
|
|
if ext == "" || id == "" {
|
|
http.NotFound(w, r)
|
|
return
|
|
}
|
|
if r.FormValue("reload") != "" {
|
|
Reload(id)
|
|
}
|
|
lang := strings.ToLower(r.FormValue("lang"))
|
|
download := path.Base(dir) == "download"
|
|
if h.serve(w, r, id, ext, lang, download) == ErrNotFound {
|
|
http.NotFound(w, r)
|
|
}
|
|
// Ignore other errors.
|
|
}
|