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/*******************************************************************************
uBlock - a browser extension to block requests.
Copyright (C) 2015 Raymond Hill
This program 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.
This program 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 this program. If not, see {http://www.gnu.org/licenses/}.
Home: https://github.com/gorhill/uBlock
*/
/* global onmessage, postMessage */
'use strict';
/******************************************************************************/
var listEntries = Object.create(null);
/******************************************************************************/
// Helpers
var rescape = function(s) {
return s.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
};
/******************************************************************************/
var fromNetFilter = function(details) {
var lists = [];
var entry, pos;
for ( var path in listEntries ) {
entry = listEntries[path];
if ( entry === undefined ) {
continue;
}
pos = entry.content.indexOf(details.compiledFilter);
if ( pos === -1 ) {
continue;
}
lists.push({
title: entry.title,
supportURL: entry.supportURL
});
}
var response = {};
response[details.rawFilter] = lists;
postMessage({
id: details.id,
response: response
});
};
/******************************************************************************/
// Looking up filter lists from a cosmetic filter is a bit more complicated
// than with network filters:
//
// The filter is its raw representation, not its compiled version. This is
// because the cosmetic filtering engine can't translate a live cosmetic
// filter into its compiled version. Reason is I do not want to burden
// cosmetic filtering with the resource overhead of being able to re-compile
// live cosmetic filters. I want the cosmetic filtering code to be left
// completely unaffected by reverse lookup requirements.
//
// Mainly, given a CSS selector and a hostname as context, we will derive
// various versions of compiled filters and see if there are matches. This way
// the whole CPU cost is incurred by the reverse lookup code -- in a worker
// thread, and the cosmetic filtering engine incurs no cost at all.
//
// For this though, the reverse lookup code here needs some knowledge of
// the inners of the cosmetic filtering engine.
// FilterContainer.fromCompiledContent() is our reference code to create
// the various compiled versions.
var fromCosmeticFilter = function(details) {
var filter = details.rawFilter;
var exception = filter.lastIndexOf('#@#', 0) === 0;
filter = exception ? filter.slice(3) : filter.slice(2);
var candidates = Object.create(null);
var response = Object.create(null);
// First step: assuming the filter is generic, find out its compiled
// representation.
// Reference: FilterContainer.compileGenericSelector().
var reStr = '';
var matches = rePlainSelector.exec(filter);
if ( matches ) {
if ( matches[0] === filter ) { // simple CSS selector
reStr = rescape('c\vlg\v' + filter);
} else { // complex CSS selector
reStr = rescape('c\vlg+\v' + matches[0] + '\v' + filter);
}
} else if ( reHighLow.test(filter) ) { // [alt] or [title]
reStr = rescape('c\vhlg0\v' + filter);
} else if ( reHighMedium.test(filter) ) { // [href^="..."]
reStr = rescape('c\vhmg0\v') + '[a-z.-]+' + rescape('\v') + '[a-z]*' + rescape(filter);
} else { // all else
reStr = rescape('c\vhhg0\v' + filter);
}
candidates[details.rawFilter] = new RegExp(reStr + '(?:\\n|$)');
// Second step: find hostname-based versions.
// Reference: FilterContainer.compileHostnameSelector().
var pos;
var domain = details.domain;
var hostname = details.hostname;
if ( hostname !== '' ) {
for ( ;; ) {
candidates[hostname + '##' + filter] = new RegExp(
rescape('c\vh\v') +
'\\w+' +
rescape('\v' + hostname + '\v' + filter) +
'(?:\\n|$)'
);
// If there is no valid domain, there won't be any other
// version of this hostname-based filter.
if ( domain === '' ) {
break;
}
if ( hostname === domain ) {
break;
}
pos = hostname.indexOf('.');
if ( pos === -1 ) {
break;
}
hostname = hostname.slice(pos + 1);
}
}
// Last step: find entity-based versions.
// Reference: FilterContainer.compileEntitySelector().
pos = domain.indexOf('.');
if ( pos !== -1 ) {
var entity = domain.slice(0, pos);
candidates[entity + '.*##' + filter] = new RegExp(
rescape('c\ve\v' + entity + '\v' + filter) +
'(?:\\n|$)'
);
}
var re, path, entry;
for ( var candidate in candidates ) {
re = candidates[candidate];
for ( path in listEntries ) {
entry = listEntries[path];
if ( entry === undefined ) {
continue;
}
if ( re.test(entry.content) === false ) {
continue;
}
if ( response[candidate] === undefined ) {
response[candidate] = [];
}
response[candidate].push({
title: entry.title,
supportURL: entry.supportURL
});
}
}
postMessage({
id: details.id,
response: response
});
};
var rePlainSelector = /^([#.][\w-]+)/;
var reHighLow = /^[a-z]*\[(?:alt|title)="[^"]+"\]$/;
var reHighMedium = /^\[href\^="https?:\/\/([^"]{8})[^"]*"\]$/;
/******************************************************************************/
onmessage = function(e) {
var msg = e.data;
switch ( msg.what ) {
case 'resetLists':
listEntries = Object.create(null);
break;
case 'setList':
listEntries[msg.details.path] = msg.details;
break;
case 'fromNetFilter':
fromNetFilter(msg);
break;
case 'fromCosmeticFilter':
fromCosmeticFilter(msg);
break;
}
};
/******************************************************************************/
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