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