The ultimate URL purifier
As of
This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://update.greasyfork.org/scripts/492078/1360585/pURLfy.js
class Purlfy extends EventTarget {
redirectEnabled = false;
lambdaEnabled = false;
maxIterations = 5;
#log = console.log.bind(console, "\x1b[38;2;220;20;60m[pURLfy]\x1b[0m");
#paramDecoders = {
"url": decodeURIComponent,
"base64": s => decodeURIComponent(escape(atob(s.replaceAll('_', '/').replaceAll('-', '+')))),
"slice": (s, start, end) => s.slice(parseInt(start), end ? parseInt(end) : undefined),
};
#zeroStatistics = {
url: 0,
param: 0,
decoded: 0,
redirected: 0,
char: 0
};
#statistics = { ...this.#zeroStatistics };
#rules = {};
#AsyncFunction = async function() {}.constructor;
constructor(options) {
super();
this.redirectEnabled = options?.redirectEnabled ?? this.redirectEnabled;
this.lambdaEnabled = options?.lambdaEnabled ?? this.lambdaEnabled;
this.maxIterations = options?.maxIterations ?? this.maxIterations;
Object.assign(this.#statistics, options?.statistics);
this.#log = options?.log ?? this.#log;
}
clearStatistics() {
const increment = {};
for (const [key, value] of Object.entries(this.#statistics)) {
increment[key] = -value;
}
this.#incrementStatistics(increment);
}
clearRules() {
this.#rules = {};
}
getStatistics() {
return { ...this.#statistics };
}
importRules(rules) {
Object.assign(this.#rules, rules);
}
#udfOrType(value, type) { // If the given value is of the given type or undefined
return value === undefined || typeof value === type;
}
#validRule(rule) { // Check if the given rule is valid
if (!rule || !rule.mode || !rule.description || !rule.author) return false;
switch (rule.mode) {
case "white":
case "black":
return Array.isArray(rule.params);
case "param":
return Array.isArray(rule.params) && (rule.decode === undefined || Array.isArray(rule.decode)) && this.#udfOrType(rule.continue, "boolean");
case "regex":
return false; // Not implemented yet
case "redirect":
return this.redirectEnabled && this.#udfOrType(rule.continue, "boolean");
case "lambda":
return this.lambdaEnabled && typeof rule.lambda === "string" && this.#udfOrType(rule.continue, "boolean");
default:
return false;
}
}
#matchRule(parts) { // Iteratively match the longest rule for the given URL parts
let fallbackRule = null; // Most precise fallback rule
let currentRules = this.#rules;
for (const part of parts) {
if (currentRules.hasOwnProperty("")) {
fallbackRule = currentRules[""];
}
if (currentRules.hasOwnProperty(part + "/")) {
currentRules = currentRules[part + "/"];
} else if (currentRules.hasOwnProperty(part)) {
const rule = currentRules[part];
if (this.#validRule(rule)) {
return rule;
}
}
}
if (this.#validRule(fallbackRule)) {
return fallbackRule;
}
return null;
}
async #applyRule(urlObj, rule, logFunc) { // Apply the given rule to the given URL object, returning the new URL object, whether to continue and the mode-specific incremental statistics
const mode = rule.mode;
const increment = { ...this.#zeroStatistics }; // Incremental statistics
const lengthBefore = urlObj.href.length;
const paramsCntBefore = urlObj.searchParams.size;
let shallContinue = false;
switch (mode) { // Purifies `urlObj` based on the rule
case "white": { // Whitelist mode
const newParams = new URLSearchParams();
for (const param of rule.params) {
if (urlObj.searchParams.has(param)) {
newParams.set(param, urlObj.searchParams.get(param));
}
}
urlObj.search = newParams.toString();
break;
}
case "black": { // Blacklist mode
for (const param of rule.params) {
urlObj.searchParams.delete(param);
}
break;
}
case "param": { // Specific param mode
// Decode given parameter to be used as a new URL
let paramValue = null;
for (const param of rule.params) { // Find the first available parameter value
if (urlObj.searchParams.has(param)) {
paramValue = urlObj.searchParams.get(param);
break;
}
}
if (!paramValue) {
logFunc("Parameter(s) not found:", rule.params.join(", "));
break;
}
let dest = paramValue;
let success = true;
for (const cmd of (rule.decode ?? ["url"])) {
const args = cmd.split(":");
const name = args[0];
const decoder = this.#paramDecoders[name];
if (!decoder) {
logFunc("Invalid decoder:", cmd);
success = false;
break;
}
try {
dest = decoder(dest, ...args.slice(1));
} catch (e) {
logFunc(`Error decoding parameter with decoder "${name}":`, e);
break;
}
}
if (!success) break;
if (URL.canParse(dest)) { // Valid URL
urlObj = new URL(dest);
} else { // Invalid URL
logFunc("Invalid URL:", dest);
break;
}
shallContinue = rule.continue ?? true;
increment.decoded++;
break;
}
case "regex": { // Regex mode
logFunc("Regex mode not implemented yet");
break;
}
case "redirect": { // Redirect mode
if (!this.redirectEnabled) {
logFunc("Redirect mode is disabled.");
break;
}
let r = null;
try {
r = await fetch(urlObj.href, {
method: "HEAD",
redirect: "manual"
});
} catch (e) {
logFunc("Error fetching URL:", e);
break;
}
if ((r.status === 301 || r.status === 302) && r.headers.has("location")) {
let dest = r.headers.get("location");
urlObj = new URL(dest);
shallContinue = rule.continue ?? true;
increment.redirected++;
}
break;
}
case "lambda": {
if (!this.lambdaEnabled) {
logFunc("Lambda mode is disabled.");
break;
}
try {
const lambda = new this.#AsyncFunction("url", rule.lambda);
urlObj = await lambda(urlObj);
shallContinue = rule.continue ?? true;
} catch (e) {
logFunc("Error executing lambda:", e);
}
break;
}
default: {
logFunc("Invalid mode:", mode);
break;
}
}
const paramsCntAfter = urlObj.searchParams.size;
increment.param += (["white", "black"].includes(mode)) ? (paramsCntBefore - paramsCntAfter) : 0;
increment.char += Math.max(lengthBefore - urlObj.href.length, 0); // Prevent negative char count
return [urlObj, shallContinue, increment];
}
#incrementStatistics(increment) {
for (const [key, value] of Object.entries(increment)) {
this.#statistics[key] += value;
}
if (typeof CustomEvent === "function") {
this.dispatchEvent(new CustomEvent("statisticschange", {
detail: increment
}));
} else {
this.dispatchEvent(new Event("statisticschange"));
}
}
async purify(originalUrl) { // Purify the given URL based on `rules`
let increment = { ...this.#zeroStatistics }; // Incremental statistics of a single purification
let shallContinue = true;
let firstRule = null;
let iteration = 0;
let urlObj;
this.#log("Purifying URL:", originalUrl);
if (URL.canParse(originalUrl)) {
urlObj = new URL(originalUrl);
} else {
this.#log(`Cannot parse URL ${originalUrl}`);
return {
url: originalUrl,
rule: "N/A"
}
}
while (shallContinue && iteration++ < this.maxIterations) {
const logi = (...args) => this.#log(`[#${iteration}]`, ...args);
const protocol = urlObj.protocol;
if (protocol !== "http:" && protocol !== "https:") { // Not a valid HTTP URL
logi(`Not a HTTP URL: ${urlObj.href}`);
break;
}
const hostAndPath = urlObj.host + urlObj.pathname;
const parts = hostAndPath.split("/").filter(part => part !== "");
const rule = this.#matchRule(parts);
if (!rule) { // No matching rule found
logi(`No matching rule found for ${urlObj.href}.`);
break;
}
firstRule ??= rule;
logi(`Matching rule: ${rule.description} by ${rule.author}`);
let singleIncrement; // Incremental statistics for the current iteration
[urlObj, shallContinue, singleIncrement] = await this.#applyRule(urlObj, rule, logi);
for (const [key, value] of Object.entries(singleIncrement)) {
increment[key] += value;
}
logi("Purified URL:", urlObj.href);
}
if (firstRule && originalUrl !== urlObj.href) { // Increment statistics only if a rule was applied and URL has been changed
increment.url++;
this.#incrementStatistics(increment);
}
return {
url: urlObj.href,
rule: firstRule ? `${firstRule.description} by ${firstRule.author}` : "N/A"
};
}
}
if (typeof module !== "undefined" && module.exports) {
module.exports = Purlfy; // Export for Node.js
} else {
this.Purlfy = Purlfy; // Export for browser
}