Adding upstream version 1.0.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

server.go

@@ -0,0 +1,84 @@
+// 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"
+	"time"
+)
+
+type captchaHandler struct {
+	imgWidth  int
+	imgHeight int
+}
+
+// Server returns a handler that serves HTTP requests with image
+// 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 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")
+		if err := WriteImage(&content, id, h.imgWidth, h.imgHeight); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+		}
+	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)
+	}
+	download := path.Base(dir) == "download"
+	if h.serve(w, r, id, ext, download) == ErrNotFound {
+		http.NotFound(w, r)
+	}
+	// Ignore other errors.
+}