1/* -*- Mode: JavaScript; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2/* vim: set ts=8 sts=2 et sw=2 tw=80: */
3/* This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6
7/* dash_detect_stream_switch.sjs
8 *
9 * Parses requests for DASH manifests and ensures stream switching takes place
10 * by verifying the subsegments downloaded and the streams they belong to.
11 * If unexpected subsegments (byte ranges) are requested, the script will
12 * will respond with a 404.
13 */
14
15var DEBUG = false;
16
17function parseQuery(request, key) {
18  var params = request.queryString.split('&');
19  if (DEBUG) {
20    dump("DASH-SJS: request params = \"" + params + "\"\n");
21  }
22  for (var j = 0; j < params.length; ++j) {
23    var p = params[j];
24	if (p == key)
25	  return true;
26    if (p.indexOf(key + "=") === 0)
27	  return p.substring(key.length + 1);
28	if (p.indexOf("=") < 0 && key === "")
29	  return p;
30  }
31  return false;
32}
33
34function handleRequest(request, response)
35{
36  try {
37    var name = parseQuery(request, "name");
38    var range = request.hasHeader("Range") ? request.getHeader("Range")
39                                           : undefined;
40
41    // Should not get request for 1st subsegment from 2nd stream, nor 2nd
42    // subsegment from 1st stream.
43    if (name == "dash-webm-video-320x180.webm" && range == "bytes=25514-32767" ||
44        name == "dash-webm-video-428x240.webm" && range == "bytes=228-35852")
45    {
46      throw "Should not request " + name + " with byte-range " + range;
47    } else {
48      var rangeSplit = range.split("=");
49      if (rangeSplit.length != 2) {
50        throw "DASH-SJS: ERROR: invalid number of tokens (" + rangeSplit.length +
51              ") delimited by \'=\' in \'Range\' header.";
52      }
53      var offsets = rangeSplit[1].split("-");
54      if (offsets.length != 2) {
55        throw "DASH-SJS: ERROR: invalid number of tokens (" + offsets.length +
56              ") delimited by \'-\' in \'Range\' header.";
57      }
58      var startOffset = parseInt(offsets[0]);
59      var endOffset = parseInt(offsets[1]);
60      var file = Components.classes["@mozilla.org/file/directory_service;1"].
61                            getService(Components.interfaces.nsIProperties).
62                            get("CurWorkD", Components.interfaces.nsIFile);
63      var fis  = Components.classes['@mozilla.org/network/file-input-stream;1'].
64                            createInstance(Components.interfaces.nsIFileInputStream);
65      var bis  = Components.classes["@mozilla.org/binaryinputstream;1"].
66                            createInstance(Components.interfaces.nsIBinaryInputStream);
67
68      var paths = "tests/dom/media/test/" + name;
69      var split = paths.split("/");
70      for (var i = 0; i < split.length; ++i) {
71        file.append(split[i]);
72      }
73
74      fis.init(file, -1, -1, false);
75      // Exception: start offset should be within file bounds.
76      if (startOffset > file.fileSize) {
77        throw "Starting offset [" + startOffset + "] is after end of file [" +
78              file.fileSize + "].";
79      }
80      // End offset may be too large in the MPD. Real world HTTP servers just
81      // return what data they can; do the same here - reduce the end offset.
82      if (endOffset >= file.fileSize) {
83        if (DEBUG) {
84          dump("DASH-SJS: reducing endOffset [" + endOffset + "] to fileSize [" +
85               (file.fileSize-1) + "]\n");
86        }
87        endOffset = file.fileSize-1;
88      }
89      fis.seek(Components.interfaces.nsISeekableStream.NS_SEEK_SET, startOffset);
90      bis.setInputStream(fis);
91
92      var byteLengthToRead = endOffset + 1 - startOffset;
93      var totalBytesExpected = byteLengthToRead + startOffset;
94      if (DEBUG) {
95        dump("DASH-SJS: byteLengthToRead = " + byteLengthToRead +
96             " byteLengthToRead+startOffset = " + totalBytesExpected +
97             " fileSize = " + file.fileSize + "\n");
98      }
99
100      var bytes = bis.readBytes(byteLengthToRead);
101      response.setStatusLine(request.httpVersion, 206, "Partial Content");
102      response.setHeader("Content-Length", ""+bytes.length, false);
103      response.setHeader("Content-Type", "application/dash+xml", false);
104      var contentRange = "bytes " + startOffset + "-" + endOffset + "/" +
105                         file.fileSize;
106      response.setHeader("Content-Range", contentRange, false);
107      response.write(bytes, bytes.length);
108      bis.close();
109    }
110  } catch (e) {
111    dump ("DASH-SJS-ERROR: " + e + "\n");
112    response.setStatusLine(request.httpVersion, 404, "Not found");
113  }
114}
115