web-apps/apps/common/checkExtendedPDF.js

/*
 * (c) Copyright Ascensio System SIA 2010-2023
 *
 * This program is a free software product. You can redistribute it and/or
 * modify it under the terms of the GNU Affero General Public License (AGPL)
 * version 3 as published by the Free Software Foundation. In accordance with
 * Section 7(a) of the GNU AGPL its Section 15 shall be amended to the effect
 * that Ascensio System SIA expressly excludes the warranty of non-infringement
 * of any third-party rights.
 *
 * This program is distributed WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR  PURPOSE. For
 * details, see the GNU AGPL at: http://www.gnu.org/licenses/agpl-3.0.html
 *
 * You can contact Ascensio System SIA at 20A-6 Ernesta Birznieka-Upish
 * street, Riga, Latvia, EU, LV-1050.
 *
 * The  interactive user interfaces in modified source and object code versions
 * of the Program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU AGPL version 3.
 *
 * Pursuant to Section 7(b) of the License you must retain the original Product
 * logo when distributing the program. Pursuant to Section 7(e) we decline to
 * grant you any rights under trademark law for use of our trademarks.
 *
 * All the Product's GUI elements, including illustrations and icon sets, as
 * well as technical writing content are licensed under the terms of the
 * Creative Commons Attribution-ShareAlike 4.0 International. See the License
 * terms at http://creativecommons.org/licenses/by-sa/4.0/legalcode
 *
 */
function checkExtendedPDF(directUrl, key, url, token, callback) {
    var limit = 110;
    if (directUrl) {
        downloadPartialy(directUrl, limit, {}, function(text) {
            callback(isExtendedPDFFile(text))
        });
    } else {
        var headers = {
            'Authorization': 'Bearer ' + token,
            'x-url': encodeURI(url)
        }
        var handlerUrl = "../../../../downloadfile/"+encodeURIComponent(key);
        downloadPartialy(handlerUrl, limit, headers, function(text) {
            callback(isExtendedPDFFile(text))
        });
    }
}
function isExtendedPDFFile(text) {
    if (!text) {
        return false;
    }
    const indexFirst = text.indexOf('%\xCD\xCA\xD2\xA9\x0D');
    if (indexFirst === -1) {
        return false;
    }

    let pFirst = text.substring(indexFirst + 6);

    if (!pFirst.startsWith('1 0 obj\x0A<<\x0A')) {
        return false;
    }

    pFirst = pFirst.substring(11);

    let signature = 'ONLYOFFICEFORM';
    const indexStream = pFirst.indexOf('stream\x0D\x0A');
    const indexMeta = pFirst.indexOf(signature);

    if (indexStream === -1 || indexMeta === -1 || indexStream < indexMeta) {
        return false;
    }

    let pMeta = pFirst.substring(indexMeta);
    pMeta = pMeta.substring(signature.length + 3);

    let indexMetaLast = pMeta.indexOf(' ');
    if (indexMetaLast === -1) {
        return false;
    }

    pMeta = pMeta.substring(indexMetaLast + 1);

    indexMetaLast = pMeta.indexOf(' ');
    if (indexMetaLast === -1) {
        return false;
    }

    return true;
}
function downloadPartialy(url, limit, headers, callback) {
    var callbackCalled = false;
    var xhr = new XMLHttpRequest();
    //value of responseText always has the current content received from the server, even if it's incomplete
    xhr.responseType = "text";
    xhr.overrideMimeType('text/xml; charset=iso-8859-1');
    xhr.onreadystatechange = function () {
        if (callbackCalled) {
            return;
        }
        if (xhr.readyState === 4 && (xhr.status === 200 || xhr.status === 206 || xhr.status === 1223)) {
            callbackCalled = true;
            callback(xhr.responseText);
        } else if (xhr.readyState === 3 && xhr.responseText.length >= limit) {
            callbackCalled = true;
            var res = xhr.responseText;
            xhr.abort();
            callback(res);
        }
    };
    xhr.open('GET', url, true);
    xhr.setRequestHeader('Range', 'bytes=0-' + limit); // the bytes (incl.) you request
    for (var header in headers) {
        if (headers.hasOwnProperty(header)) {
            xhr.setRequestHeader(header, headers[header]);
        }
    }
    xhr.send();
}