urlskip.js (6331B) - View raw
/******************************************************************************* uBlock Origin - a comprehensive, efficient content blocker Copyright (C) 2022-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 */ /** * @trustedOption urlskip * * @description * Extract a URL from another URL according to one or more transformation steps, * thereby skipping over intermediate network request(s) to remote servers. * Requires a trusted source. * * @param steps * A serie of space-separated directives representing the transformation steps * to perform to extract the final URL to which a network request should be * redirected. * * Supported directives: * * `?name`: extract the value of parameter `name` as the current string. * * `&i`: extract the name of the parameter at position `i` as the current * string. The position is 1-based. * * `#`: extract the hash as the current string. * * `/.../`: extract the first capture group of a regex as the current string. * * `+https`: prepend the current string with `https://`. * * `-base64`: decode the current string as a base64-encoded string. * * `-safebase64`: decode the current string as a safe base64-encoded string. * * `-uricomponent`: decode the current string as a URI encoded string. * * `-blocked`: allow the redirection of blocked requests. By default, blocked * requests can't by urlskip'ed. * * At any given step, the currently extracted string may not necessarily be * a valid URL, and more transformation steps may be needed to obtain a valid * URL once all the steps are applied. * * An unsupported step or a failed step will abort the transformation and no * redirection will be performed. * * The final step is expected to yield a valid URL. If the result is not a * valid URL, no redirection will be performed. * * @example * ||example.com/path/to/tracker$urlskip=?url * ||example.com/path/to/tracker$urlskip=?url ?to * ||pixiv.net/jump.php?$urlskip=&1 * ||podtrac.com/pts/redirect.mp3/$urlskip=/\/redirect\.mp3\/(.*?\.mp3\b)/ +https * * */ export function urlSkip(url, blocked, steps, directive = {}) { try { let redirectBlocked = false; let urlout = url; for ( const step of steps ) { const urlin = urlout; const c0 = step.charCodeAt(0); // Extract from hash if ( c0 === 0x23 && step === '#' ) { // # const pos = urlin.indexOf('#'); urlout = pos !== -1 ? urlin.slice(pos+1) : ''; continue; } // Extract from URL parameter name at position i if ( c0 === 0x26 ) { // & const i = (parseInt(step.slice(1)) || 0) - 1; if ( i < 0 ) { return; } const url = new URL(urlin); if ( i >= url.searchParams.size ) { return; } const params = Array.from(url.searchParams.keys()); urlout = decodeURIComponent(params[i]); continue; } // Enforce https if ( c0 === 0x2B && step === '+https' ) { // + const s = urlin.replace(/^https?:\/\//, ''); if ( /^[\w-]:\/\//.test(s) ) { return; } urlout = `https://${s}`; continue; } // Decode if ( c0 === 0x2D ) { // - // Base64 if ( step === '-base64' ) { urlout = self.atob(urlin); continue; } // Safe Base64 if ( step === '-safebase64' ) { if ( urlSkip.safeBase64Replacer === undefined ) { urlSkip.safeBase64Map = { '-': '+', '_': '/' }; urlSkip.safeBase64Replacer = s => urlSkip.safeBase64Map[s]; } urlout = urlin.replace(/[-_]/g, urlSkip.safeBase64Replacer); urlout = self.atob(urlout); continue; } // URI component if ( step === '-uricomponent' ) { urlout = decodeURIComponent(urlin); continue; } // Enable skip of blocked requests if ( step === '-blocked' ) { redirectBlocked = true; continue; } } // Regex extraction from first capture group if ( c0 === 0x2F ) { // / const re = directive.cache ?? new RegExp(step.slice(1, -1)); if ( directive.cache === null ) { directive.cache = re; } const match = re.exec(urlin); if ( match === null ) { return; } if ( match.length <= 1 ) { return; } urlout = match[1]; continue; } // Extract from URL parameter if ( c0 === 0x3F ) { // ? urlout = (new URL(urlin)).searchParams.get(step.slice(1)); if ( urlout === null ) { return; } if ( urlout.includes(' ') ) { urlout = urlout.replace(/ /g, '%20'); } continue; } // Unknown directive return; } const urlfinal = new URL(urlout); if ( urlfinal.protocol !== 'https:' ) { if ( urlfinal.protocol !== 'http:' ) { return; } } if ( blocked && redirectBlocked !== true ) { return; } return urlout; } catch { } }