1 files changed, 133 insertions, 0 deletions
diff --git a/netwerk/dns/mdns/libmdns/fallback/DataReader.jsm b/netwerk/dns/mdns/libmdns/fallback/DataReader.jsm
new file mode 100644
index 000000000..a20c1dc32
--- /dev/null
+++ b/netwerk/dns/mdns/libmdns/fallback/DataReader.jsm
@@ -0,0 +1,133 @@
+/* -*- Mode: js; js-indent-level: 2; indent-tabs-mode: nil; tab-width: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+/* jshint esnext: true, moz: true */
+
+'use strict';
+
+this.EXPORTED_SYMBOLS = ['DataReader'];
+
+class DataReader {
+  // `data` is `Uint8Array`
+  constructor(data, startByte = 0) {
+    this._data = data;
+    this._cursor = startByte;
+  }
+
+  get buffer() {
+    return this._data.buffer;
+  }
+
+  get data() {
+    return this._data;
+  }
+
+  get eof() {
+    return this._cursor >= this._data.length;
+  }
+
+  getBytes(length = 1) {
+    if (!length) {
+      return new Uint8Array();
+    }
+
+    let end = this._cursor + length;
+    if (end > this._data.length) {
+      return new Uint8Array();
+    }
+
+    let uint8Array = new Uint8Array(this.buffer.slice(this._cursor, end));
+    this._cursor += length;
+
+    return uint8Array;
+  }
+
+  getString(length) {
+    let uint8Array = this.getBytes(length);
+    return _uint8ArrayToString(uint8Array);
+  }
+
+  getValue(length) {
+    let uint8Array = this.getBytes(length);
+    return _uint8ArrayToValue(uint8Array);
+  }
+
+  getLabel(decompressData) {
+    let parts = [];
+    let partLength;
+
+    while ((partLength = this.getValue(1))) {
+      // If a length has been specified instead of a pointer,
+      // read the string of the specified length.
+      if (partLength !== 0xc0) {
+        parts.push(this.getString(partLength));
+        continue;
+      }
+
+      // TODO: Handle case where we have a pointer to the label
+      parts.push(String.fromCharCode(0xc0) + this.getString(1));
+      break;
+    }
+
+    let label = parts.join('.');
+
+    return _decompressLabel(label, decompressData || this._data);
+  }
+}
+
+/**
+ * @private
+ */
+function _uint8ArrayToValue(uint8Array) {
+  let length = uint8Array.length;
+  if (length === 0) {
+    return null;
+  }
+
+  let value = 0;
+  for (let i = 0; i < length; i++) {
+    value = value << 8;
+    value += uint8Array[i];
+  }
+
+  return value;
+}
+
+/**
+ * @private
+ */
+function _uint8ArrayToString(uint8Array) {
+  let length = uint8Array.length;
+  if (length === 0) {
+    return '';
+  }
+
+  let results = [];
+  for (let i = 0; i < length; i += 1024) {
+    results.push(String.fromCharCode.apply(null, uint8Array.subarray(i, i + 1024)));
+  }
+
+  return results.join('');
+}
+
+/**
+ * @private
+ */
+function _decompressLabel(label, decompressData) {
+  let result = '';
+
+  for (let i = 0, length = label.length; i < length; i++) {
+    if (label.charCodeAt(i) !== 0xc0) {
+      result += label.charAt(i);
+      continue;
+    }
+
+    i++;
+
+    let reader = new DataReader(decompressData, label.charCodeAt(i));
+    result += _decompressLabel(reader.getLabel(), decompressData);
+  }
+
+  return result;
+}