node-smb-server/lib/utils.js

A Pure JavaScript SMB Server Implementation

/*
 *  Copyright 2015 Adobe Systems Incorporated. All rights reserved.
 *  This file is licensed to you under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License. You may obtain a copy
 *  of the License at http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software distributed under
 *  the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
 *  OF ANY KIND, either express or implied. See the License for the specific language
 *  governing permissions and limitations under the License.
 */

'use strict';

var crypto = require('crypto');
var Path = require('path');

var Long = require('long');
var mime = require('mime');
var unorm = require('unorm');

// register (unofficial) mime type for InDesign files (.indd)
mime.define({ 'application/x-indesign': ['indd' ] });

/**
 * Lookup a mime type based on file extension.
 *
 * @param {String} path resource path
 * @param {String} [fallback] fallback mime type if none is found
 * @return {String} mime type associated with the specified file type
 */
function lookupMimeType(path, fallback) {
  return mime.lookup(path, fallback);
}

/**
 * Number of milliseconds between Jan 1, 1601, 00:00:00 UTC and Jan 1, 1970, 00:00:00.0.
 */
var DELTA_EPOCH_MS = 11644473600000;

/**
 * indicates that extended attribute (EA) support is required on this file
 */
var FILE_NEED_EA = 0x80;

/**
 * Converts the system time (number of milliseconds since Jan 1, 1970, 00:00:00 UTC)
 * to the SMB format time (number of 100ns since Jan 1, 1601, 00:00:00 UTC).
 *
 * @param {Number} ms number of milliseconds since Jan 1, 1970, 00:00:00 UTC.
 * @return {Long} a 64bit signed integer representing the number of 100ns since Jan 1, 1601, 00:00:00 UTC.
 */
function systemToSMBTime(ms) {
  var l = Long.fromNumber(ms);
  return l.add(DELTA_EPOCH_MS).multiply(10000);
}

/**
 * Converts the SMB format time (number of 100ns since Jan 1, 1601, 00:00:00 UTC)
 * to the number of milliseconds since Jan 1, 1970, 00:00:00 UTC.
 *
 * @param {Long} l a 64bit signed integer representing the number of 100ns since Jan 1, 1601, 00:00:00 UTC.
 * @return {Number} number of milliseconds since Jan 1, 1970, 00:00:00 UTC.
 */
function smbToSystemTime(l) {
  return l.div(10000).subtract(DELTA_EPOCH_MS).toNumber();
}

/**
 * Converts the system time (number of milliseconds since Jan 1, 1970, 00:00:00 UTC)
 * to the legacy 16bit SMB_DATE representation.
 *
 * @param {Number} ms number of milliseconds since Jan 1, 1970, 00:00:00 UTC.
 * @return {Number} a 16bit integer SMB_DATE value.
 */
function systemToLegacySMBDate(ms) {
  var date = new Date(ms);
  var result = date.getDate();
  result += (date.getMonth() + 1) << 5;
  result += (date.getFullYear() - 1980) << 9;
  return result;
}

/**
 * Converts the system time (number of milliseconds since Jan 1, 1970, 00:00:00 UTC)
 * to the legacy 16bit SMB_TIME representation.
 *
 * @param {Number} ms number of milliseconds since Jan 1, 1970, 00:00:00 UTC.
 * @return {Number} a 16bit integer SMB_TIME value.
 */
function systemToLegacySMBTime(ms) {
  var date = new Date(ms);
  var result = Math.floor(date.getSeconds() / 2);
  result += date.getMinutes() << 5;
  result += date.getHours() << 11;
  return result;
}

/**
 * Converts the legacy 16bit SMB_DATE and SMB_TIME representation to system time (number of milliseconds since Jan 1, 1970, 00:00:00 UTC).
 *
 * @param {Number} smbDate 16bit integer SMB_DATE
 * @param {Number} smbTime 16bit integer SMB_TIME
 * @return {Number} number of milliseconds since Jan 1, 1970, 00:00:00 UTC.
 */
function legacySMBToSystemDateTime(smbDate, smbTime) {
  var year = ((smbDate & 0xfe00) >> 9) + 1980;
  var month = ((smbDate & 0x01e0) >> 5) - 1;
  var day = smbDate & 0x001f;
  var hour = (smbTime & 0xf800) >> 11;
  var minutes = (smbTime & 0x07e0) >> 5;
  var seconds = (smbTime & 0x001f) * 2;
  return new Date(year, month, day, hour, minutes, seconds).getTime();
}

/**
 * Reads the 8 byte SMB format time and returns the
 * milliseconds since 1 January 1970 00:00:00 UTC (Unix Epoch).
 *
 * The following rules apply:
 * If the read 64bit value is -1 (0xFFFFFFFFFFFFFFFF) the return value is -1;
 * If the read 64bit value is 0 (0x0000000000000000) the return value is 0;
 * All other values are converted to the Unix Epoch.
 *
 * @param {Buffer} buf
 * @param {Number} pos
 * @return {Number} milliseconds since 1 January 1970 00:00:00 UTC (Unix Epoch)
 */
function readTimestamp(buf, pos) {
  var timeLow = buf.readUInt32LE(pos);
  var timeHigh = buf.readUInt32LE(pos + 4);
  if (timeLow === 0xffffffff && timeHigh === 0xffffffff) {
    return -1;
  } else if (!timeHigh && !timeLow) {
    return 0;
  } else {
    return new Date(smbToSystemTime(new Long(timeLow, timeHigh))).getTime();
  }
}

/**
 * Parses an encoded FEA (full extended attribute) list.
 *
 * @param {Buffer} buf
 * @param {Number} pos
 * @return {Object[]} array of objects representing the extended attributes
 */
function parseFEAList(buf, pos) {
  if (buf.length - pos < 4) {
    return null;
  }
  var result = [];
  var sizeOfListInBytes = buf.readUInt32LE(pos);
  if (sizeOfListInBytes <= 4) {
    return result;
  }
  pos += 4;
  buf = buf.slice(pos, pos + sizeOfListInBytes - 4);
  pos = 0;
  var flag, nameLength, valueLenght;
  while (pos < buf.length - 5) {
    var ea = {};
    ea.offset = pos;
    flag = buf.readUInt8(pos);
    pos += 1;
    nameLength = buf.readUInt8(pos);
    pos += 1;
    valueLenght = buf.readUInt32LE(pos);
    pos += 2;
    // zero-terminated ascii string
    ea.name = buf.slice(pos, pos + nameLength).toString('ascii');
    pos += nameLength + 1;
    // non-zero-terminated ascii string
    ea.value = buf.slice(pos, pos + valueLenght).toString('ascii');
    pos += valueLenght;
    ea.needEA = !!(flag & FILE_NEED_EA);
    result.push(ea);
  }
  return result;
}

/**
 * Extracts the bytes of an 0x0000-delimited utf16le encoded string (excluding the delimiter)
 * @param buf
 * @param pos
 * @return {Buffer} bytes of a utf16le encoded string (excluding the 0x0000 delimiter)
 */
function extractUnicodeBytes(buf, pos) {
  var off = pos;
  while (buf.readUInt16LE(off)) {
    off += 2;
  }

  return buf.slice(pos, off);
}

/**
 * Extracts the bytes of an 0x00-delimited ascii encoded string (excluding the delimiter)
 * @param buf
 * @param pos
 * @return {Buffer} bytes of an ascii encoded string (excluding the 0x00 delimiter)
 */
function extractAsciiBytes(buf, pos) {
  var off = pos;
  while (buf.readUInt8(off)) {
    off += 1;
  }

  return buf.slice(pos, off);
}

function calculatePadLength(offset, alignment) {
  var pad = alignment - (offset % alignment);
  return pad < alignment ? pad : 0;
}

/**
 * Normalize a SMB file path or pattern. Converts backslashes to slashes, makes sure
 * the path name is absolute, and removes a trailing slash.
 *
 * @param {String} name name to normalize
 * @returns {String} normalized name
 */
function normalizeSMBFileName(name) {
  name = name.replace(/\\/g, '/');
  if (!name.length || (name.length && name.charAt(0) !== '/')) {
    name = '/' + name;
  }
  if (name.length > 1 && name.substr(-1) === '/') {
    name = name.substr(0, name.length - 1);
  }
  return name;
}

function bufferEquals(a, b) {
  if (!Buffer.isBuffer(a) || !Buffer.isBuffer(b)) {
    return undefined;
  }
  if (typeof a.equals === 'function') {
    // node >= v0.12
    return a.equals(b);
  }

  if (a.length !== b.length) {
    return false;
  }

  for (var i = 0; i < a.length; i++) {
    if (a[i] !== b[i]) {
      return false;
    }
  }

  return true;
}

/**
 * Returns the last segment of a path
 *
 * @param {String} path
 * @return {String} last segment of path
 */
function getPathName(path) {
  var pos = path.lastIndexOf(Path.sep);
  if (pos === -1) {
    return path;
  }
  return path.slice(pos + 1);
}

/**
 * Returns the file extension
 *
 * @param {String} name path or file name
 * @returns {String} file extension
 */
function getFileExtension(name) {
  var pos = name.lastIndexOf('.');
  if (pos === -1) {
    return name;
  }
  return name.slice(pos + 1);
}

/**
 * Returns the parent path
 *
 * @param {String} path
 * @return {String} parent path
 */
function getParentPath(path) {
  var pos = path.lastIndexOf(Path.sep);
  if (pos === -1) {
    return null;
  }
  if (pos === 0) {
    return Path.sep;
  }
  return path.slice(0, pos);
}

/**
 * Strips the specified parent path
 *
 * @param {String} path
 * @param {String} parentPath
 * @return {String} stripped path
 */
function stripParentPath(path, parentPath) {
  if (path === parentPath) {
    return '';
  }
  if (path.indexOf(parentPath) === 0) {
    path = path.substr(parentPath.length);
    if (path.length > 1 && path.substr(-1) === Path.sep) {
      // strip trailing slash
      path = path.substr(0, path.length - 1);
    }
  }
  return path;
}

function getRandomInt(min, max) {
  return Math.floor(Math.random() * (max - min + 1)) + min;
}

function generateRawUUID() {
  var timeLow, timeMid, timeHiAndVersion, clockSeqHiAndReserved, clockSeqLow, node;

  timeLow = getRandomInt(0, Math.pow(2, 32) - 1);
  timeMid = getRandomInt(0, Math.pow(2, 16) - 1);
  timeHiAndVersion = 0x4000 | getRandomInt(0, Math.pow(2, 12) - 1);
  clockSeqHiAndReserved = 0x80 | getRandomInt(0, Math.pow(2, 6) - 1);
  clockSeqLow = getRandomInt(0, Math.pow(2, 8) - 1);
  node = crypto.randomBytes(6);

  var buf = new Buffer(16);
  var off = 0;
  buf.writeUInt32LE(timeLow, off);
  off += 4;
  buf.writeUInt16LE(timeMid, off);
  off += 2;
  buf.writeUInt16LE(timeHiAndVersion, off);
  off += 2;
  buf.writeUInt8(clockSeqHiAndReserved, off);
  off += 1;
  buf.writeUInt8(clockSeqLow, off);
  off += 1;
  node.copy(buf, off);

  return buf;
}

function rawUUIDToString(buf) {
  var uuid = parseRawUUID(buf);
  return decimalToHex(uuid.timeLow, 8)
    + '-' + decimalToHex(uuid.timeMid, 4)
    + '-' + decimalToHex(uuid.timeHiAndVersion, 4)
    + '-' + decimalToHex(uuid.clockSeqHiAndReserved, 2) + decimalToHex(uuid.clockSeqLow, 2)
    + '-' + uuid.node.toString('hex');
}

function parseRawUUID(buf) {
  var uuid = {};
  var off = 0;
  uuid.timeLow = buf.readUInt32LE(off);
  off += 4;
  uuid.timeMid = buf.readUInt16LE(off);
  off += 2;
  uuid.timeHiAndVersion = buf.readUInt16LE(off);
  off += 2;
  uuid.clockSeqHiAndReserved = buf.readUInt8(off);
  off += 1;
  uuid.clockSeqLow = buf.readUInt8(off);
  off += 1;
  uuid.node = buf.slice(off, off + 6);
  return uuid;
}

function rawUUIDFromString(str) {
  // todo validation / error handling
  var parts = str.split('-');
  // parts.length === 5
  var b1 = new Buffer(parts[0], 'hex');
  var b2 = new Buffer(parts[1], 'hex');
  var b3 = new Buffer(parts[2], 'hex');
  var b4 = new Buffer(parts[3].substr(0, 2), 'hex');
  var b5 = new Buffer(parts[3].substr(2), 'hex');
  var b6 = new Buffer(parts[4], 'hex');
  return Buffer.concat([ b1, b2, b3, b4, b5, b6 ]);
}

function decimalToHex(d, padding) {
  var hex = Number(d).toString(16);
  padding = typeof (padding) === 'undefined' || padding === null ? 2 : padding;
  while (hex.length < padding) {
    hex = '0' + hex;
  }
  return hex;
}

function unicodeNormalize(str) {
  // need to normalize unicode strings in order to avoid issues related to different code points (e.g. 'caf\u00E9' vs 'cafe\u0301').
  // note that using the builtin string.normalize('NFKD') does not work...
  return unorm.nfkd(str);
}

function unicodeEquals(str1, str2) {
  return unicodeNormalize(str1) === unicodeNormalize(str2);
}

module.exports.EMPTY_BUFFER = new Buffer(0);

module.exports.ZERO_GUID = new Buffer(16);
module.exports.ZERO_GUID.fill(0);

module.exports.lookupMimeType = lookupMimeType;
module.exports.systemToSMBTime = systemToSMBTime;
module.exports.smbToSystemTime = smbToSystemTime;
module.exports.systemToLegacySMBDate = systemToLegacySMBDate;
module.exports.systemToLegacySMBTime = systemToLegacySMBTime;
module.exports.legacySMBToSystemDateTime = legacySMBToSystemDateTime;
module.exports.readTimestamp = readTimestamp;
module.exports.parseFEAList = parseFEAList;
module.exports.extractUnicodeBytes = extractUnicodeBytes;
module.exports.extractAsciiBytes = extractAsciiBytes;
module.exports.calculatePadLength = calculatePadLength;
module.exports.normalizeSMBFileName = normalizeSMBFileName;
module.exports.bufferEquals = bufferEquals;
module.exports.getParentPath = getParentPath;
module.exports.stripParentPath = stripParentPath;
module.exports.getPathName = getPathName;
module.exports.getFileExtension = getFileExtension;
module.exports.generateRawUUID = generateRawUUID;
module.exports.rawUUIDToString = rawUUIDToString;
module.exports.rawUUIDFromString = rawUUIDFromString;
module.exports.unicodeNormalize = unicodeNormalize;
module.exports.unicodeEquals = unicodeEquals;