uBlock/src/js/url-net-filtering.js

/*******************************************************************************

    uBlock Origin - a browser extension to black/white list requests.
    Copyright (C) 2015-present 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
*/

'use strict';

/******************************************************************************/

// The purpose of log filtering is to create ad hoc filtering rules, to
// diagnose and assist in the creation of custom filters.

µBlock.URLNetFiltering = (( ) => {

/*******************************************************************************

buckets: map of [hostname + type]
     bucket: array of rule entries, sorted from shorter to longer url
rule entry: { url, action }

*******************************************************************************/

/******************************************************************************/

const actionToNameMap = {
    1: 'block',
    2: 'allow',
    3: 'noop'
};

const nameToActionMap = {
    'block': 1,
    'allow': 2,
     'noop': 3
};

const knownInvalidTypes = new Set([
    'doc',
    'main_frame',
]);

/******************************************************************************/

const RuleEntry = function(url, action) {
    this.url = url;
    this.action = action;
};

/******************************************************************************/

const indexOfURL = function(entries, url) {
    // TODO: binary search -- maybe, depends on common use cases
    const urlLen = url.length;
    // URLs must be ordered by increasing length.
    for ( let i = 0; i < entries.length; i++ ) {
        const entry = entries[i];
        if ( entry.url.length > urlLen ) { break; }
        if ( entry.url === url ) { return i; }
    }
    return -1;
};

/******************************************************************************/

const indexOfMatch = function(entries, url) {
    const urlLen = url.length;
    let i = entries.length;
    while ( i-- ) {
        if ( entries[i].url.length <= urlLen ) {
            break;
        }
    }
    if ( i !== -1 ) {
        do {
            if ( url.startsWith(entries[i].url) ) {
                return i;
            }
        } while ( i-- );
    }
    return -1;
};

/******************************************************************************/

const indexFromLength = function(entries, len) {
    // TODO: binary search -- maybe, depends on common use cases
    // URLs must be ordered by increasing length.
    for ( let i = 0; i < entries.length; i++ ) {
        if ( entries[i].url.length > len ) { return i; }
    }
    return -1;
};

/******************************************************************************/

const addRuleEntry = function(entries, url, action) {
    const entry = new RuleEntry(url, action);
    const i = indexFromLength(entries, url.length);
    if ( i === -1 ) {
        entries.push(entry);
    } else {
        entries.splice(i, 0, entry);
    }
};

/******************************************************************************/

const URLNetFiltering = function() {
    this.reset();
};

/******************************************************************************/

URLNetFiltering.prototype.reset = function() {
    this.rules = new Map();
    // registers, filled with result of last evaluation
    this.context = '';
    this.url = '';
    this.type = '';
    this.r = 0;
    this.changed = false;
    this.decomposedSource = [];
};

/******************************************************************************/

URLNetFiltering.prototype.assign = function(other) {
    // Remove rules not in other
    for ( const key of this.rules.keys() ) {
        if ( other.rules.has(key) === false ) {
            this.rules.delete(key);
        }
    }
    // Add/change rules in other
    for ( const entry of other.rules ) {
        this.rules.set(entry[0], entry[1].slice());
    }
    this.changed = true;
};

/******************************************************************************/

URLNetFiltering.prototype.setRule = function(srcHostname, url, type, action) {
    if ( action === 0 ) {
        return this.removeRule(srcHostname, url, type);
    }
    const bucketKey = srcHostname + ' ' + type;
    let entries = this.rules.get(bucketKey);
    if ( entries === undefined ) {
        entries = [];
        this.rules.set(bucketKey, entries);
    }
    const i = indexOfURL(entries, url);
    if ( i !== -1 ) {
        const entry = entries[i];
        if ( entry.action === action ) { return false; }
        entry.action = action;
    } else {
        addRuleEntry(entries, url, action);
    }
    this.changed = true;
    return true;
};

/******************************************************************************/

URLNetFiltering.prototype.removeRule = function(srcHostname, url, type) {
    const bucketKey = srcHostname + ' ' + type;
    const entries = this.rules.get(bucketKey);
    if ( entries === undefined ) { return false; }
    const i = indexOfURL(entries, url);
    if ( i === -1 ) { return false; }
    entries.splice(i, 1);
    if ( entries.length === 0 ) {
        this.rules.delete(bucketKey);
    }
    this.changed = true;
    return true;
};

/******************************************************************************/

URLNetFiltering.prototype.evaluateZ = function(context, target, type) {
    this.r = 0;
    if ( this.rules.size === 0 ) {
        return 0;
    }
    µBlock.decomposeHostname(context, this.decomposedSource);
    for ( let shn of this.decomposedSource ) {
        this.context = shn;
        let entries = this.rules.get(shn + ' ' + type);
        if ( entries !== undefined ) {
            let i = indexOfMatch(entries, target);
            if ( i !== -1 ) {
                let entry = entries[i];
                this.url = entry.url;
                this.type = type;
                this.r = entry.action;
                return this.r;
            }
        }
        entries = this.rules.get(shn + ' *');
        if ( entries !== undefined ) {
            let i = indexOfMatch(entries, target);
            if ( i !== -1 ) {
                let entry = entries[i];
                this.url = entry.url;
                this.type = '*';
                this.r = entry.action;
                return this.r;
            }
        }
    }
    return 0;
};

/******************************************************************************/

URLNetFiltering.prototype.mustAllowCellZ = function(context, target, type) {
    return this.evaluateZ(context, target, type).r === 2;
};

/******************************************************************************/

URLNetFiltering.prototype.mustBlockOrAllow = function() {
    return this.r === 1 || this.r === 2;
};

/******************************************************************************/

URLNetFiltering.prototype.toLogData = function() {
    if ( this.r === 0 ) { return; }
    return {
        source: 'dynamicUrl',
        result: this.r,
        rule: [
            this.context,
            this.url,
            this.type,
            this.intToActionMap.get(this.r)
        ],
        raw: this.context + ' ' +
             this.url + ' ' +
             this.type + ' ' +
             this.intToActionMap.get(this.r)
    };
};

URLNetFiltering.prototype.intToActionMap = new Map([
    [ 1, ' block' ],
    [ 2, ' allow' ],
    [ 3, ' noop' ]
]);

/******************************************************************************/

URLNetFiltering.prototype.copyRules = function(other, context, urls, type) {
    let i = urls.length;
    while ( i-- ) {
        const url = urls[i];
        other.evaluateZ(context, url, type);
        const otherOwn = other.r !== 0 &&
                         other.context === context &&
                         other.url === url &&
                         other.type === type;
        this.evaluateZ(context, url, type);
        const  thisOwn = this.r !== 0 &&
                         this.context === context &&
                         this.url === url &&
                         this.type === type;
        if ( otherOwn && !thisOwn ) {
            this.setRule(context, url, type, other.r);
            this.changed = true;
        }
        if ( !otherOwn && thisOwn ) {
            this.removeRule(context, url, type);
            this.changed = true;
        }
    }
    return this.changed;
};

/******************************************************************************/

// "url-filtering:" hostname url type action

URLNetFiltering.prototype.toArray = function() {
    const out = [];
    for ( var item of this.rules ) {
        const key = item[0];
        let pos = key.indexOf(' ');
        const hn = key.slice(0, pos);
        pos = key.lastIndexOf(' ');
        const type = key.slice(pos + 1);
        const entries = item[1];
        for ( let i = 0; i < entries.length; i++ ) {
            const entry = entries[i];
            out.push(
                hn + ' ' +
                entry.url + ' ' +
                type + ' ' +
                actionToNameMap[entry.action]
            );
        }
    }
    return out;
};

URLNetFiltering.prototype.toString = function() {
    return this.toArray().sort().join('\n');
};

/******************************************************************************/

URLNetFiltering.prototype.fromString = function(text) {
    this.reset();
    const lineIter = new µBlock.LineIterator(text);
    while ( lineIter.eot() === false ) {
        this.addFromRuleParts(lineIter.next().trim().split(/\s+/));
    }
};

/******************************************************************************/

URLNetFiltering.prototype.validateRuleParts = function(parts) {
    if ( parts.length !== 4 ) { return; }
    if ( parts[1].indexOf('://') === -1 ) { return; }
    if ( /[^a-z_-]+/.test(parts[2]) || knownInvalidTypes.has(parts[2]) ) {
        return;
    }
    if ( nameToActionMap.hasOwnProperty(parts[3]) === false ) { return; }
    return parts;
};

/******************************************************************************/

URLNetFiltering.prototype.addFromRuleParts = function(parts) {
    if ( this.validateRuleParts(parts) !== undefined ) {
        this.setRule(parts[0], parts[1], parts[2], nameToActionMap[parts[3]]);
        return true;
    }
    return false;
};

URLNetFiltering.prototype.removeFromRuleParts = function(parts) {
    if ( this.validateRuleParts(parts) !== undefined ) {
        this.removeRule(parts[0], parts[1], parts[2]);
        return true;
    }
    return false;
};

/******************************************************************************/

return URLNetFiltering;

/******************************************************************************/

})();

/******************************************************************************/

µBlock.sessionURLFiltering = new µBlock.URLNetFiltering();
µBlock.permanentURLFiltering = new µBlock.URLNetFiltering();

/******************************************************************************/