util.ts

// Copyright 2018-2020 the oak authors. All rights reserved. MIT license.

import { isAbsolute, join, normalize, resolve, sep } from "./deps.ts";
import { createHttpError } from "./httpError.ts";

/** Safely decode a URI component, where if it fails, instead of throwing,
 * just returns the original string
 */
export function decodeComponent(text: string) {
  try {
    return decodeURIComponent(text);
  } catch {
    return text;
  }
}

/** Determines if a string "looks" like HTML */
export function isHtml(value: string): boolean {
  return /^\s*<(?:!DOCTYPE|html|body)/i.test(value);
}

/*!
 * Adapted directly from https://github.com/pillarjs/resolve-path
 * which is licensed as follows:
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2014 Jonathan Ong <me@jongleberry.com>
 * Copyright (c) 2015-2018 Douglas Christopher Wilson <doug@somethingdoug.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * 'Software'), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

const UP_PATH_REGEXP = /(?:^|[\\/])\.\.(?:[\\/]|$)/;

export function resolvePath(relativePath: string): string;
export function resolvePath(rootPath: string, relativePath: string): string;
export function resolvePath(rootPath: string, relativePath?: string): string {
  let path = relativePath;
  let root = rootPath;

  // root is optional, similar to root.resolve
  if (arguments.length === 1) {
    path = rootPath;
    root = Deno.cwd();
  }

  if (path == null) {
    throw new TypeError("Argument relativePath is required.");
  }

  // containing NULL bytes is malicious
  if (path.includes("\0")) {
    throw createHttpError(400, "Malicious Path");
  }

  // path should never be absolute
  if (isAbsolute(path)) {
    throw createHttpError(400, "Malicious Path");
  }

  // path outside root
  if (UP_PATH_REGEXP.test(normalize("." + sep + path))) {
    throw createHttpError(403);
  }

  // join the relative path
  return normalize(join(resolve(root), path));
}