michael@0: /* -*- Mode: JavaScript; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* vim: set ts=8 sts=2 et sw=2 tw=80: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /* dash_detect_stream_switch.sjs
michael@0:  *
michael@0:  * Parses requests for DASH manifests and ensures stream switching takes place
michael@0:  * by verifying the subsegments downloaded and the streams they belong to.
michael@0:  * If unexpected subsegments (byte ranges) are requested, the script will
michael@0:  * will respond with a 404.
michael@0:  */
michael@0: 
michael@0: var DEBUG = false;
michael@0: 
michael@0: function parseQuery(request, key) {
michael@0:   var params = request.queryString.split('&');
michael@0:   if (DEBUG) {
michael@0:     dump("DASH-SJS: request params = \"" + params + "\"\n");
michael@0:   }
michael@0:   for (var j = 0; j < params.length; ++j) {
michael@0:     var p = params[j];
michael@0: 	if (p == key)
michael@0: 	  return true;
michael@0:     if (p.indexOf(key + "=") === 0)
michael@0: 	  return p.substring(key.length + 1);
michael@0: 	if (p.indexOf("=") < 0 && key === "")
michael@0: 	  return p;
michael@0:   }
michael@0:   return false;
michael@0: }
michael@0: 
michael@0: function handleRequest(request, response)
michael@0: {
michael@0:   try {
michael@0:     var name = parseQuery(request, "name");
michael@0:     var range = request.hasHeader("Range") ? request.getHeader("Range")
michael@0:                                            : undefined;
michael@0:     
michael@0:     // Should not get request for 1st subsegment from 2nd stream, nor 2nd
michael@0:     // subsegment from 1st stream.
michael@0:     if (name == "dash-webm-video-320x180.webm" && range == "bytes=25514-32767" ||
michael@0:         name == "dash-webm-video-428x240.webm" && range == "bytes=228-35852") 
michael@0:     {
michael@0:       throw "Should not request " + name + " with byte-range " + range;
michael@0:     } else {
michael@0:       var rangeSplit = range.split("=");
michael@0:       if (rangeSplit.length != 2) {
michael@0:         throw "DASH-SJS: ERROR: invalid number of tokens (" + rangeSplit.length +
michael@0:               ") delimited by \'=\' in \'Range\' header.";
michael@0:       }
michael@0:       var offsets = rangeSplit[1].split("-");
michael@0:       if (offsets.length != 2) {
michael@0:         throw "DASH-SJS: ERROR: invalid number of tokens (" + offsets.length +
michael@0:               ") delimited by \'-\' in \'Range\' header.";
michael@0:       }
michael@0:       var startOffset = parseInt(offsets[0]);
michael@0:       var endOffset = parseInt(offsets[1]);
michael@0:       var file = Components.classes["@mozilla.org/file/directory_service;1"].
michael@0:                             getService(Components.interfaces.nsIProperties).
michael@0:                             get("CurWorkD", Components.interfaces.nsILocalFile);
michael@0:       var fis  = Components.classes['@mozilla.org/network/file-input-stream;1'].
michael@0:                             createInstance(Components.interfaces.nsIFileInputStream);
michael@0:       var bis  = Components.classes["@mozilla.org/binaryinputstream;1"].
michael@0:                             createInstance(Components.interfaces.nsIBinaryInputStream);
michael@0: 
michael@0:       var paths = "tests/content/media/test/" + name;
michael@0:       var split = paths.split("/");
michael@0:       for (var i = 0; i < split.length; ++i) {
michael@0:         file.append(split[i]);
michael@0:       }
michael@0: 
michael@0:       fis.init(file, -1, -1, false);
michael@0:       // Exception: start offset should be within file bounds.
michael@0:       if (startOffset > file.fileSize) {
michael@0:         throw "Starting offset [" + startOffset + "] is after end of file [" +
michael@0:               file.fileSize + "].";
michael@0:       }
michael@0:       // End offset may be too large in the MPD. Real world HTTP servers just
michael@0:       // return what data they can; do the same here - reduce the end offset.
michael@0:       if (endOffset >= file.fileSize) {
michael@0:         if (DEBUG) {
michael@0:           dump("DASH-SJS: reducing endOffset [" + endOffset + "] to fileSize [" +
michael@0:                (file.fileSize-1) + "]\n");
michael@0:         }
michael@0:         endOffset = file.fileSize-1;
michael@0:       }
michael@0:       fis.seek(Components.interfaces.nsISeekableStream.NS_SEEK_SET, startOffset);
michael@0:       bis.setInputStream(fis);
michael@0:       
michael@0:       var byteLengthToRead = endOffset + 1 - startOffset;
michael@0:       var totalBytesExpected = byteLengthToRead + startOffset;
michael@0:       if (DEBUG) {
michael@0:         dump("DASH-SJS: byteLengthToRead = " + byteLengthToRead +
michael@0:              " byteLengthToRead+startOffset = " + totalBytesExpected +
michael@0:              " fileSize = " + file.fileSize + "\n");
michael@0:       }
michael@0: 
michael@0:       var bytes = bis.readBytes(byteLengthToRead);
michael@0:       response.setStatusLine(request.httpVersion, 206, "Partial Content");
michael@0:       response.setHeader("Content-Length", ""+bytes.length, false);
michael@0:       response.setHeader("Content-Type", "application/dash+xml", false);
michael@0:       var contentRange = "bytes " + startOffset + "-" + endOffset + "/" +
michael@0:                          file.fileSize;
michael@0:       response.setHeader("Content-Range", contentRange, false);
michael@0:       response.write(bytes, bytes.length);
michael@0:       bis.close();
michael@0:     }
michael@0:   } catch (e) {
michael@0:     dump ("DASH-SJS-ERROR: " + e + "\n");
michael@0:     response.setStatusLine(request.httpVersion, 404, "Not found");
michael@0:   }
michael@0: }