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/**
* GNU LibreJS - A browser add-on to block nonfree nontrivial JavaScript.
*
* Copyright (C) 2018 Giorgio Maone <giorgio@maone.net>
*
* This file is part of GNU LibreJS.
*
* GNU LibreJS is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GNU LibreJS is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU LibreJS. If not, see <http://www.gnu.org/licenses/>.
*/
/**
This class parses HTTP response headers to extract both the
MIME Content-type and the character set to be used, if specified,
to parse textual data through a decoder.
*/
const BOM = [0xEF, 0xBB, 0xBF];
const DECODER_PARAMS = { stream: true };
class ResponseMetaData {
constructor(request) {
let { responseHeaders } = request;
this.headers = {};
for (let h of responseHeaders) {
if (/^\s*Content-(Type|Disposition)\s*$/i.test(h.name)) {
let propertyName = h.name.split('-')[1].trim();
propertyName = `content${propertyName.charAt(0).toUpperCase()}${propertyName.substring(1).toLowerCase()}`;
this[propertyName] = h.value;
this.headers[propertyName] = h;
}
}
this.computedCharset = '';
}
get charset() {
let charset = '';
if (this.contentType) {
let m = this.contentType.match(/;\s*charset\s*=\s*(\S+)/);
if (m) {
charset = m[1];
}
}
Object.defineProperty(this, 'charset', { value: charset, writable: false, configurable: true });
return this.computedCharset = charset;
}
decode(data) {
let charset = this.charset;
let decoder = this.createDecoder();
let text = decoder.decode(data, DECODER_PARAMS);
if (!charset && /html/i.test(this.contentType)) {
// missing HTTP charset, sniffing in content...
if (data[0] === BOM[0] && data[1] === BOM[1] && data[2] === BOM[2]) {
// forced UTF-8, nothing to do
return text;
}
// let's try figuring out the charset from <meta> tags
let parser = new DOMParser();
let doc = parser.parseFromString(text, 'text/html');
let meta = doc.querySelectorAll('meta[charset], meta[http-equiv="content-type"], meta[content*="charset"]');
for (let m of meta) {
charset = m.getAttribute('charset');
if (!charset) {
let match = m.getAttribute('content').match(/;\s*charset\s*=\s*([\w-]+)/i)
if (match) charset = match[1];
}
if (charset) {
decoder = this.createDecoder(charset, null);
if (decoder) {
this.computedCharset = charset;
return decoder.decode(data, DECODER_PARAMS);
}
}
}
}
return text;
}
createDecoder(charset = this.charset, def = 'latin1') {
if (charset) {
try {
return new TextDecoder(charset);
} catch (e) {
console.error(e);
}
}
return def ? new TextDecoder(def) : null;
}
}
ResponseMetaData.UTF8BOM = new Uint8Array(BOM);
module.exports = { ResponseMetaData };
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