lib/display/content_disposition.js

/**
 * @licstart The following is the entire license notice for the
 * Javascript code in this page
 *
 * Copyright 2020 Mozilla Foundation
 *
 * Licensed 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 CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @licend The above is the entire license notice for the
 * Javascript code in this page
 */
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.getFilenameFromContentDispositionHeader = getFilenameFromContentDispositionHeader;

function getFilenameFromContentDispositionHeader(contentDisposition) {
  let needsEncodingFixup = true;
  let tmp = toParamRegExp("filename\\*", "i").exec(contentDisposition);

  if (tmp) {
    tmp = tmp[1];
    let filename = rfc2616unquote(tmp);
    filename = unescape(filename);
    filename = rfc5987decode(filename);
    filename = rfc2047decode(filename);
    return fixupEncoding(filename);
  }

  tmp = rfc2231getparam(contentDisposition);

  if (tmp) {
    const filename = rfc2047decode(tmp);
    return fixupEncoding(filename);
  }

  tmp = toParamRegExp("filename", "i").exec(contentDisposition);

  if (tmp) {
    tmp = tmp[1];
    let filename = rfc2616unquote(tmp);
    filename = rfc2047decode(filename);
    return fixupEncoding(filename);
  }

  function toParamRegExp(attributePattern, flags) {
    return new RegExp("(?:^|;)\\s*" + attributePattern + "\\s*=\\s*" + "(" + '[^";\\s][^;\\s]*' + "|" + '"(?:[^"\\\\]|\\\\"?)+"?' + ")", flags);
  }

  function textdecode(encoding, value) {
    if (encoding) {
      if (!/^[\x00-\xFF]+$/.test(value)) {
        return value;
      }

      try {
        const decoder = new TextDecoder(encoding, {
          fatal: true
        });
        const bytes = Array.from(value, function (ch) {
          return ch.charCodeAt(0) & 0xff;
        });
        value = decoder.decode(new Uint8Array(bytes));
        needsEncodingFixup = false;
      } catch (e) {
        if (/^utf-?8$/i.test(encoding)) {
          try {
            value = decodeURIComponent(escape(value));
            needsEncodingFixup = false;
          } catch (err) {}
        }
      }
    }

    return value;
  }

  function fixupEncoding(value) {
    if (needsEncodingFixup && /[\x80-\xff]/.test(value)) {
      value = textdecode("utf-8", value);

      if (needsEncodingFixup) {
        value = textdecode("iso-8859-1", value);
      }
    }

    return value;
  }

  function rfc2231getparam(contentDispositionStr) {
    const matches = [];
    let match;
    const iter = toParamRegExp("filename\\*((?!0\\d)\\d+)(\\*?)", "ig");

    while ((match = iter.exec(contentDispositionStr)) !== null) {
      let [, n, quot, part] = match;
      n = parseInt(n, 10);

      if (n in matches) {
        if (n === 0) {
          break;
        }

        continue;
      }

      matches[n] = [quot, part];
    }

    const parts = [];

    for (let n = 0; n < matches.length; ++n) {
      if (!(n in matches)) {
        break;
      }

      let [quot, part] = matches[n];
      part = rfc2616unquote(part);

      if (quot) {
        part = unescape(part);

        if (n === 0) {
          part = rfc5987decode(part);
        }
      }

      parts.push(part);
    }

    return parts.join("");
  }

  function rfc2616unquote(value) {
    if (value.startsWith('"')) {
      const parts = value.slice(1).split('\\"');

      for (let i = 0; i < parts.length; ++i) {
        const quotindex = parts[i].indexOf('"');

        if (quotindex !== -1) {
          parts[i] = parts[i].slice(0, quotindex);
          parts.length = i + 1;
        }

        parts[i] = parts[i].replace(/\\(.)/g, "$1");
      }

      value = parts.join('"');
    }

    return value;
  }

  function rfc5987decode(extvalue) {
    const encodingend = extvalue.indexOf("'");

    if (encodingend === -1) {
      return extvalue;
    }

    const encoding = extvalue.slice(0, encodingend);
    const langvalue = extvalue.slice(encodingend + 1);
    const value = langvalue.replace(/^[^']*'/, "");
    return textdecode(encoding, value);
  }

  function rfc2047decode(value) {
    if (!value.startsWith("=?") || /[\x00-\x19\x80-\xff]/.test(value)) {
      return value;
    }

    return value.replace(/=\?([\w-]*)\?([QqBb])\?((?:[^?]|\?(?!=))*)\?=/g, function (matches, charset, encoding, text) {
      if (encoding === "q" || encoding === "Q") {
        text = text.replace(/_/g, " ");
        text = text.replace(/=([0-9a-fA-F]{2})/g, function (match, hex) {
          return String.fromCharCode(parseInt(hex, 16));
        });
        return textdecode(charset, text);
      }

      try {
        text = atob(text);
      } catch (e) {}

      return textdecode(charset, text);
    });
  }

  return "";
}