express/lib/utils.js

/**
 * Module dependencies.
 */

var mime = require('send').mime;
var crc32 = require('buffer-crc32');
var basename = require('path').basename;
var deprecate = require('util').deprecate;
var proxyaddr = require('proxy-addr');

/**
 * Simple detection of charset parameter in content-type
 */
var charsetRegExp = /;\s*charset\s*=/;

/**
 * Deprecate function, like core `util.deprecate`,
 * but with NODE_ENV and color support.
 *
 * @param {Function} fn
 * @param {String} msg
 * @return {Function}
 * @api private
 */

exports.deprecate = function(fn, msg){
  if (process.env.NODE_ENV === 'test') return fn;

  // prepend module name
  msg = 'express: ' + msg;

  if (process.stderr.isTTY) {
    // colorize
    msg = '\x1b[31;1m' + msg + '\x1b[0m';
  }

  return deprecate(fn, msg);
};

/**
 * Return ETag for `body`.
 *
 * @param {String|Buffer} body
 * @return {String}
 * @api private
 */

exports.etag = function(body){
  return '"' + crc32.signed(body) + '"';
};

/**
 * Check if `path` looks absolute.
 *
 * @param {String} path
 * @return {Boolean}
 * @api private
 */

exports.isAbsolute = function(path){
  if ('/' == path[0]) return true;
  if (':' == path[1] && '\\' == path[2]) return true;
  if ('\\\\' == path.substring(0, 2)) return true; // Microsoft Azure absolute path
};

/**
 * Flatten the given `arr`.
 *
 * @param {Array} arr
 * @return {Array}
 * @api private
 */

exports.flatten = function(arr, ret){
  ret = ret || [];
  var len = arr.length;
  for (var i = 0; i < len; ++i) {
    if (Array.isArray(arr[i])) {
      exports.flatten(arr[i], ret);
    } else {
      ret.push(arr[i]);
    }
  }
  return ret;
};

/**
 * Normalize the given `type`, for example "html" becomes "text/html".
 *
 * @param {String} type
 * @return {Object}
 * @api private
 */

exports.normalizeType = function(type){
  return ~type.indexOf('/')
    ? acceptParams(type)
    : { value: mime.lookup(type), params: {} };
};

/**
 * Normalize `types`, for example "html" becomes "text/html".
 *
 * @param {Array} types
 * @return {Array}
 * @api private
 */

exports.normalizeTypes = function(types){
  var ret = [];

  for (var i = 0; i < types.length; ++i) {
    ret.push(exports.normalizeType(types[i]));
  }

  return ret;
};

/**
 * Generate Content-Disposition header appropriate for the filename.
 * non-ascii filenames are urlencoded and a filename* parameter is added
 *
 * @param {String} filename
 * @return {String}
 * @api private
 */

exports.contentDisposition = function(filename){
  var ret = 'attachment';
  if (filename) {
    filename = basename(filename);
    // if filename contains non-ascii characters, add a utf-8 version ala RFC 5987
    ret = /[^\040-\176]/.test(filename)
      ? 'attachment; filename=' + encodeURI(filename) + '; filename*=UTF-8\'\'' + encodeURI(filename)
      : 'attachment; filename="' + filename + '"';
  }

  return ret;
};

/**
 * Parse accept params `str` returning an
 * object with `.value`, `.quality` and `.params`.
 * also includes `.originalIndex` for stable sorting
 *
 * @param {String} str
 * @return {Object}
 * @api private
 */

function acceptParams(str, index) {
  var parts = str.split(/ *; */);
  var ret = { value: parts[0], quality: 1, params: {}, originalIndex: index };

  for (var i = 1; i < parts.length; ++i) {
    var pms = parts[i].split(/ *= */);
    if ('q' == pms[0]) {
      ret.quality = parseFloat(pms[1]);
    } else {
      ret.params[pms[0]] = pms[1];
    }
  }

  return ret;
}

/**
 * Compile "proxy trust" value to function.
 *
 * @param  {Boolean|String|Number|Array|Function} val
 * @return {Function}
 * @api private
 */

exports.compileTrust = function(val) {
  if (typeof val === 'function') return val;

  if (val === true) {
    // Support plain true/false
    return function(){ return true };
  }

  if (typeof val === 'number') {
    // Support trusting hop count
    return function(a, i){ return i < val };
  }

  if (typeof val === 'string') {
    // Support comma-separated values
    val = val.split(/ *, */);
  }

  return proxyaddr.compile(val || []);
}

/**
 * Set the charset in a given Content-Type string.
 *
 * @param {String} type
 * @param {String} charset
 * @return {String}
 * @api private
 */

exports.setCharset = function(type, charset){
  if (!type || !charset) return type;

  var exists = charsetRegExp.test(type);

  // removing existing charset
  if (exists) {
    var parts = type.split(';');

    for (var i = 1; i < parts.length; i++) {
      if (charsetRegExp.test(';' + parts[i])) {
        parts.splice(i, 1);
        break;
      }
    }

    type = parts.join(';');
  }

  return type + '; charset=' + charset;
};