Run user-supplied regexes in worker threads with a timeout

backend/package-lock.json

@@ -3402,6 +3402,11 @@
       "resolved": "https://registry.npmjs.org/regexp-tree/-/regexp-tree-0.1.14.tgz",
       "integrity": "sha512-59v5A90TAh4cAMyDQEOzcnsu4q7Wb10RsyTjngEnJIZsWYM4siVGu+JmLT1WsxHvOWhiu4YS20XiTuxWMeVoHQ=="
     },
+    "regexp-worker": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/regexp-worker/-/regexp-worker-1.1.0.tgz",
+      "integrity": "sha512-IDDOhDlI972T7bexYwyw+JKdqFsBtJvX8RA+ChVwjhgcK/gv4eG3oZu8Rbidnamh2U2b0ZWdawKksjzY2dmVFw=="
+    },
     "registry-auth-token": {
       "version": "4.1.1",
       "resolved": "https://registry.npmjs.org/registry-auth-token/-/registry-auth-token-4.1.1.tgz",

backend/package.json

@@ -53,6 +53,7 @@
     "passport-custom": "^1.0.5",
     "passport-oauth2": "^1.5.0",
     "reflect-metadata": "^0.1.12",
+    "regexp-worker": "^1.1.0",
     "safe-regex": "^2.0.2",
     "seedrandom": "^3.0.1",
     "sharp": "^0.23.4",

backend/src/RegExpRunner.ts

@@ -0,0 +1,96 @@
+import { RegExpWorker, TimeoutError } from "regexp-worker";
+import { CooldownManager } from "knub";
+import { MINUTES } from "./utils";
+import { EventEmitter } from "events";
+
+const isTimeoutError = (a): a is TimeoutError => {
+  return a.message != null && a.elapsedTimeMs != null;
+};
+
+export class RegExpTimeoutError extends Error {
+  constructor(message: string, public elapsedTimeMs: number) {
+    super(message);
+  }
+}
+
+export function allowTimeout(err: RegExpTimeoutError | Error) {
+  if (err instanceof RegExpTimeoutError) {
+    return null;
+  }
+
+  throw err;
+}
+
+const REGEX_TIMEOUT = 100; // ms
+
+const REGEX_FAIL_TO_COOLDOWN_COUNT = 3; // If a regex fails this many times, it goes on cooldown...
+const REGEX_FAIL_COOLDOWN = 5 * MINUTES; // ...for this long
+
+export interface RegExpRunner {
+  on(event: "timeout", listener: (regexSource: string, timeoutMs: number) => void);
+  on(event: "repeatedTimeout", listener: (regexSource: string, timeoutMs: number, failTimes: number) => void);
+}
+
+/**
+ * Leverages RegExpWorker to run regular expressions in worker threads with a timeout.
+ * Repeatedly failing regexes are put on a cooldown where requests to execute them are ignored.
+ */
+export class RegExpRunner extends EventEmitter {
+  private _worker: RegExpWorker;
+
+  private cooldown: CooldownManager;
+  private failedTimes: Map<string, number>;
+
+  constructor() {
+    super();
+    this.cooldown = new CooldownManager();
+    this.failedTimes = new Map();
+  }
+
+  private get worker(): RegExpWorker {
+    if (!this._worker) {
+      this._worker = new RegExpWorker(REGEX_TIMEOUT);
+    }
+
+    return this._worker;
+  }
+
+  public async exec(regex: RegExp, str: string): Promise<null | RegExpExecArray[]> {
+    if (this.cooldown.isOnCooldown(regex.source)) {
+      return null;
+    }
+
+    try {
+      const result = await this.worker.execRegExp(regex, str);
+      return result.matches.length || regex.global ? result.matches : null;
+    } catch (e) {
+      if (isTimeoutError(e)) {
+        if (this.failedTimes.has(regex.source)) {
+          // Regex has failed before, increment fail counter
+          this.failedTimes.set(regex.source, this.failedTimes.get(regex.source) + 1);
+        } else {
+          // This is the first time this regex failed, init fail counter
+          this.failedTimes.set(regex.source, 1);
+        }
+
+        if (this.failedTimes.get(regex.source) >= REGEX_FAIL_TO_COOLDOWN_COUNT) {
+          // Regex has failed too many times, set it on cooldown
+          this.cooldown.setCooldown(regex.source, REGEX_FAIL_COOLDOWN);
+          this.failedTimes.delete(regex.source);
+          this.emit("repeatedTimeout", regex.source, REGEX_TIMEOUT, REGEX_FAIL_TO_COOLDOWN_COUNT);
+        }
+
+        this.emit("timeout", regex.source, REGEX_TIMEOUT);
+
+        throw new RegExpTimeoutError(e.message, e.elapsedTimeMs);
+      }
+
+      throw e;
+    }
+  }
+
+  public async dispose() {
+    await this.worker.dispose();
+    this._worker = null;
+  }
+}

backend/src/plugins/Automod/AutomodPlugin.ts

@@ -11,7 +11,7 @@ import { StrictValidationError } from "../../validatorUtils";
 import { ConfigPreprocessorFn } from "knub/dist/config/configTypes";
 import { availableActions } from "./actions/availableActions";
 import { clearOldRecentActions } from "./functions/clearOldRecentActions";
-import { MINUTES, SECONDS } from "../../utils";
+import { disableCodeBlocks, MINUTES, SECONDS } from "../../utils";
 import { clearOldRecentSpam } from "./functions/clearOldRecentSpam";
 import { GuildAntiraidLevels } from "../../data/GuildAntiraidLevels";
 import { GuildArchives } from "../../data/GuildArchives";
@@ -23,6 +23,10 @@ import { AntiraidClearCmd } from "./commands/AntiraidClearCmd";
 import { SetAntiraidCmd } from "./commands/SetAntiraidCmd";
 import { ViewAntiraidCmd } from "./commands/ViewAntiraidCmd";
 import { pluginInfo } from "./info";
+import { RegExpRunner } from "../../RegExpRunner";
+import { LogType } from "../../data/LogType";
+import { logger } from "../../logger";
+import { discardRegExpRunner, getRegExpRunner } from "../../regExpRunners";
 
 const defaultOptions = {
   config: {
@@ -161,6 +165,8 @@ export const AutomodPlugin = zeppelinPlugin<AutomodPluginType>()("automod", {
   async onLoad(pluginData) {
     pluginData.state.queue = new Queue();
 
+    pluginData.state.regexRunner = getRegExpRunner(`guild-${pluginData.guild.id}`);
+
     pluginData.state.recentActions = [];
     pluginData.state.clearRecentActionsInterval = setInterval(() => clearOldRecentActions(pluginData), 1 * MINUTES);
 
@@ -189,9 +195,11 @@ export const AutomodPlugin = zeppelinPlugin<AutomodPluginType>()("automod", {
     pluginData.state.cachedAntiraidLevel = await pluginData.state.antiraidLevels.get();
   },
 
-  onUnload(pluginData) {
+  async onUnload(pluginData) {
     pluginData.state.queue.clear();
 
+    discardRegExpRunner(`guild-${pluginData.guild.id}`);
+
     clearInterval(pluginData.state.clearRecentActionsInterval);
 
     clearInterval(pluginData.state.clearRecentSpamInterval);

backend/src/plugins/Automod/triggers/matchLinks.ts

@@ -10,8 +10,9 @@ import {
   verboseChannelMention,
 } from "../../../utils";
 import { MatchableTextType, matchMultipleTextTypesOnMessage } from "../functions/matchMultipleTextTypesOnMessage";
-import { TSafeRegex } from "../../../validatorUtils";
+import { TRegex } from "../../../validatorUtils";
 import { getTextMatchPartialSummary } from "../functions/getTextMatchPartialSummary";
+import { allowTimeout } from "../../../RegExpRunner";
 
 interface MatchResultType {
   type: MatchableTextType;
@@ -25,8 +26,8 @@ export const MatchLinksTrigger = automodTrigger<MatchResultType>()({
     include_subdomains: t.boolean,
     include_words: tNullable(t.array(t.string)),
     exclude_words: tNullable(t.array(t.string)),
-    include_regex: tNullable(t.array(TSafeRegex)),
-    exclude_regex: tNullable(t.array(TSafeRegex)),
+    include_regex: tNullable(t.array(TRegex)),
+    exclude_regex: tNullable(t.array(TRegex)),
     only_real_links: t.boolean,
     match_messages: t.boolean,
     match_embeds: t.boolean,
@@ -67,16 +68,18 @@ export const MatchLinksTrigger = automodTrigger<MatchResultType>()({
         // In order of specificity, regex > word > domain
 
         if (trigger.exclude_regex) {
-          for (const pattern of trigger.exclude_regex) {
-            if (pattern.test(link.input)) {
+          for (const sourceRegex of trigger.exclude_regex) {
+            const matches = await pluginData.state.regexRunner.exec(sourceRegex, link.input).catch(allowTimeout);
+            if (matches) {
               continue typeLoop;
             }
           }
         }
 
         if (trigger.include_regex) {
-          for (const pattern of trigger.include_regex) {
-            if (pattern.test(link.input)) {
+          for (const sourceRegex of trigger.include_regex) {
+            const matches = await pluginData.state.regexRunner.exec(sourceRegex, link.input).catch(allowTimeout);
+            if (matches) {
               return { extra: { type, link: link.input } };
             }
           }

backend/src/plugins/Automod/triggers/matchRegex.ts

@@ -3,8 +3,9 @@ import { transliterate } from "transliteration";
 import { automodTrigger } from "../helpers";
 import { disableInlineCode, verboseChannelMention } from "../../../utils";
 import { MatchableTextType, matchMultipleTextTypesOnMessage } from "../functions/matchMultipleTextTypesOnMessage";
-import { TSafeRegex } from "../../../validatorUtils";
 import { getTextMatchPartialSummary } from "../functions/getTextMatchPartialSummary";
+import { allowTimeout } from "../../../RegExpRunner";
+import { TRegex } from "../../../validatorUtils";
 
 interface MatchResultType {
   pattern: string;
@@ -13,7 +14,7 @@ interface MatchResultType {
 
 export const MatchRegexTrigger = automodTrigger<MatchResultType>()({
   configType: t.type({
-    patterns: t.array(TSafeRegex),
+    patterns: t.array(TRegex),
     case_sensitive: t.boolean,
     normalize: t.boolean,
     match_messages: t.boolean,
@@ -46,9 +47,9 @@ export const MatchRegexTrigger = automodTrigger<MatchResultType>()({
       }
 
       for (const sourceRegex of trigger.patterns) {
-        const regex = new RegExp(sourceRegex.source, trigger.case_sensitive ? "" : "i");
-        const test = regex.test(str);
-        if (test) {
+        const regex = new RegExp(sourceRegex.source, trigger.case_sensitive && !sourceRegex.ignoreCase ? "" : "i");
+        const matches = await pluginData.state.regexRunner.exec(regex, str).catch(allowTimeout);
+        if (matches?.length) {
           return {
             extra: {
               pattern: sourceRegex.source,

backend/src/plugins/Automod/types.ts

@@ -12,6 +12,7 @@ import { GuildAntiraidLevels } from "../../data/GuildAntiraidLevels";
 import { GuildArchives } from "../../data/GuildArchives";
 import { RecentActionType } from "./constants";
 import Timeout = NodeJS.Timeout;
+import { RegExpRunner } from "../../RegExpRunner";
 
 export const Rule = t.type({
   enabled: t.boolean,
@@ -45,6 +46,11 @@ export interface AutomodPluginType extends BasePluginType {
      */
     queue: Queue;
 
+    /**
+     * Per-server regex runner
+     */
+    regexRunner: RegExpRunner;
+
     /**
      * Recent actions are used for spam triggers
      */

backend/src/plugins/Censor/CensorPlugin.ts

@@ -6,6 +6,8 @@ import { GuildSavedMessages } from "src/data/GuildSavedMessages";
 import { onMessageCreate } from "./util/onMessageCreate";
 import { onMessageUpdate } from "./util/onMessageUpdate";
 import { trimPluginDescription } from "../../utils";
+import { discardRegExpRunner, getRegExpRunner } from "../../regExpRunners";
+import { LogsPlugin } from "../Logs/LogsPlugin";
 
 const defaultOptions: PluginOptions<CensorPluginType> = {
   config: {
@@ -51,6 +53,7 @@ export const CensorPlugin = zeppelinPlugin<CensorPluginType>()("censor", {
     `),
   },
 
+  dependencies: [LogsPlugin],
   configSchema: ConfigSchema,
   defaultOptions,
 
@@ -60,6 +63,8 @@ export const CensorPlugin = zeppelinPlugin<CensorPluginType>()("censor", {
     state.serverLogs = new GuildLogs(guild.id);
     state.savedMessages = GuildSavedMessages.getGuildInstance(guild.id);
 
+    state.regexRunner = getRegExpRunner(`guild-${pluginData.guild.id}`);
+
     state.onMessageCreateFn = msg => onMessageCreate(pluginData, msg);
     state.savedMessages.events.on("create", state.onMessageCreateFn);
 
@@ -68,6 +73,8 @@ export const CensorPlugin = zeppelinPlugin<CensorPluginType>()("censor", {
   },
 
   onUnload(pluginData) {
+    discardRegExpRunner(`guild-${pluginData.guild.id}`);
+
     pluginData.state.savedMessages.events.off("create", pluginData.state.onMessageCreateFn);
     pluginData.state.savedMessages.events.off("update", pluginData.state.onMessageUpdateFn);
   },

backend/src/plugins/Censor/types.ts

@@ -1,9 +1,10 @@
 import * as t from "io-ts";
 import { BasePluginType, eventListener } from "knub";
 import { tNullable } from "src/utils";
-import { TSafeRegex } from "src/validatorUtils";
+import { TRegex } from "src/validatorUtils";
 import { GuildLogs } from "src/data/GuildLogs";
 import { GuildSavedMessages } from "src/data/GuildSavedMessages";
+import { RegExpRunner } from "../../RegExpRunner";
 
 export const ConfigSchema = t.type({
   filter_zalgo: t.boolean,
@@ -18,7 +19,7 @@ export const ConfigSchema = t.type({
   domain_blacklist: tNullable(t.array(t.string)),
   blocked_tokens: tNullable(t.array(t.string)),
   blocked_words: tNullable(t.array(t.string)),
-  blocked_regex: tNullable(t.array(TSafeRegex)),
+  blocked_regex: tNullable(t.array(TRegex)),
 });
 export type TConfigSchema = t.TypeOf<typeof ConfigSchema>;
 
@@ -28,6 +29,8 @@ export interface CensorPluginType extends BasePluginType {
     serverLogs: GuildLogs;
     savedMessages: GuildSavedMessages;
 
+    regexRunner: RegExpRunner;
+
     onMessageCreateFn;
     onMessageUpdateFn;
   };

backend/src/plugins/Censor/util/applyFiltersToMsg.ts

@@ -8,6 +8,7 @@ import cloneDeep from "lodash.clonedeep";
 import { censorMessage } from "./censorMessage";
 import escapeStringRegexp from "escape-string-regexp";
 import { logger } from "src/logger";
+import { allowTimeout } from "../../../RegExpRunner";
 
 export async function applyFiltersToMsg(
   pluginData: PluginData<CensorPluginType>,
@@ -137,17 +138,13 @@ export async function applyFiltersToMsg(
   }
 
   // Filter regex
-  const blockedRegex: RegExp[] = config.blocked_regex || [];
-  for (const [i, regex] of blockedRegex.entries()) {
-    if (typeof regex.test !== "function") {
-      logger.info(
-        `[DEBUG] Regex <${regex}> was not a regex; index ${i} of censor.blocked_regex for guild ${pluginData.guild.name} (${pluginData.guild.id})`,
-      );
-      continue;
-    }
-
+  for (const regex of config.blocked_regex || []) {
     // We're testing both the original content and content + attachments/embeds here so regexes that use ^ and $ still match the regular content properly
-    if (regex.test(savedMessage.data.content) || regex.test(messageContent)) {
+    const matches =
+      (await pluginData.state.regexRunner.exec(regex, savedMessage.data.content).catch(allowTimeout)) ||
+      (await pluginData.state.regexRunner.exec(regex, messageContent).catch(allowTimeout));
+
+    if (matches) {
       censorMessage(pluginData, savedMessage, `blocked regex (\`${regex.source}\`) found`);
       return true;
     }

backend/src/plugins/Logs/LogsPlugin.ts

@@ -19,6 +19,9 @@ import { LogsVoiceJoinEvt, LogsVoiceLeaveEvt, LogsVoiceSwitchEvt } from "./event
 import { log } from "./util/log";
 import { LogType } from "../../data/LogType";
 import { getLogMessage } from "./util/getLogMessage";
+import { discardRegExpRunner, getRegExpRunner } from "../../regExpRunners";
+import { disableCodeBlocks } from "../../utils";
+import { logger } from "../../logger";
 
 const defaultOptions: PluginOptions<LogsPluginType> = {
   config: {
@@ -100,6 +103,24 @@ export const LogsPlugin = zeppelinPlugin<LogsPluginType>()("logs", {
 
     state.onMessageUpdateFn = (newMsg, oldMsg) => onMessageUpdate(pluginData, newMsg, oldMsg);
     state.savedMessages.events.on("update", state.onMessageUpdateFn);
+
+    state.regexRunner = getRegExpRunner(`guild-${pluginData.guild.id}`);
+    state.regexRunnerTimeoutListener = (regexSource, timeoutMs) => {
+      logger.warn(`Heavy regex (${timeoutMs}): ${regexSource}`);
+    };
+    state.regexRunnerRepeatedTimeoutListener = (regexSource, timeoutMs, failedTimes) => {
+      log(pluginData, LogType.BOT_ALERT, {
+        body:
+          `
+            The following regex has taken longer than ${timeoutMs}ms for ${failedTimes} times and has been temporarily disabled:
+          `.trim() +
+          "\n```" +
+          disableCodeBlocks(regexSource) +
+          "```",
+      });
+    };
+    state.regexRunner.on("timeout", state.regexRunnerTimeoutListener);
+    state.regexRunner.on("repeatedTimeout", state.regexRunnerRepeatedTimeoutListener);
   },
 
   onUnload(pluginData) {
@@ -108,5 +129,9 @@ export const LogsPlugin = zeppelinPlugin<LogsPluginType>()("logs", {
     pluginData.state.savedMessages.events.off("delete", pluginData.state.onMessageDeleteFn);
     pluginData.state.savedMessages.events.off("deleteBulk", pluginData.state.onMessageDeleteBulkFn);
     pluginData.state.savedMessages.events.off("update", pluginData.state.onMessageUpdateFn);
+
+    pluginData.state.regexRunner.off("timeout", pluginData.state.regexRunnerTimeoutListener);
+    pluginData.state.regexRunner.off("repeatedTimeout", pluginData.state.regexRunnerRepeatedTimeoutListener);
+    discardRegExpRunner(`guild-${pluginData.guild.id}`);
   },
 });

backend/src/plugins/Logs/types.ts

@@ -1,11 +1,12 @@
 import * as t from "io-ts";
 import { BasePluginType, eventListener } from "knub";
-import { TSafeRegex } from "src/validatorUtils";
+import { TRegex } from "src/validatorUtils";
 import { GuildLogs } from "src/data/GuildLogs";
 import { GuildSavedMessages } from "src/data/GuildSavedMessages";
 import { GuildArchives } from "src/data/GuildArchives";
 import { GuildCases } from "src/data/GuildCases";
 import { tMessageContent, tNullable } from "../../utils";
+import { RegExpRunner } from "../../RegExpRunner";
 
 export const tLogFormats = t.record(t.string, t.union([t.string, tMessageContent]));
 export type TLogFormats = t.TypeOf<typeof tLogFormats>;
@@ -16,7 +17,7 @@ const LogChannel = t.partial({
   batched: t.boolean,
   batch_time: t.number,
   excluded_users: t.array(t.string),
-  excluded_message_regexes: t.array(TSafeRegex),
+  excluded_message_regexes: t.array(TRegex),
   excluded_channels: t.array(t.string),
   format: tNullable(tLogFormats),
 });
@@ -45,6 +46,10 @@ export interface LogsPluginType extends BasePluginType {
     archives: GuildArchives;
     cases: GuildCases;
 
+    regexRunner: RegExpRunner;
+    regexRunnerTimeoutListener;
+    regexRunnerRepeatedTimeoutListener;
+
     logListener;
 
     batches: Map<string, string[]>;

backend/src/plugins/Logs/util/log.ts

@@ -4,6 +4,7 @@ import { LogType } from "src/data/LogType";
 import { TextChannel } from "eris";
 import { createChunkedMessage, noop } from "src/utils";
 import { getLogMessage } from "./getLogMessage";
+import { allowTimeout } from "../../../RegExpRunner";
 
 const excludedUserProps = ["user", "member", "mod"];
 
@@ -45,7 +46,8 @@ export async function log(pluginData: PluginData<LogsPluginType>, type: LogType,
       // If this entry contains a message with an excluded regex, skip it
       if (type === LogType.MESSAGE_DELETE && opts.excluded_message_regexes && data.message.data.content) {
         for (const regex of opts.excluded_message_regexes) {
-          if (regex.test(data.message.data.content)) {
+          const matches = await pluginData.state.regexRunner.exec(regex, data.message.data.content).catch(allowTimeout);
+          if (matches) {
             continue logChannelLoop;
           }
         }
@@ -53,7 +55,8 @@ export async function log(pluginData: PluginData<LogsPluginType>, type: LogType,
 
       if (type === LogType.MESSAGE_EDIT && opts.excluded_message_regexes && data.before.data.content) {
         for (const regex of opts.excluded_message_regexes) {
-          if (regex.test(data.before.data.content)) {
+          const matches = await pluginData.state.regexRunner.exec(regex, data.message.data.content).catch(allowTimeout);
+          if (matches) {
             continue logChannelLoop;
           }
         }

backend/src/regExpRunners.ts

@@ -0,0 +1,37 @@
+import { RegExpRunner } from "./RegExpRunner";
+
+interface RunnerInfo {
+  users: number;
+  runner: RegExpRunner;
+}
+
+const runners: Map<string, RunnerInfo> = new Map();
+
+export function getRegExpRunner(key: string) {
+  if (!runners.has(key)) {
+    const runner = new RegExpRunner();
+    runners.set(key, {
+      users: 0,
+      runner,
+    });
+  }
+
+  const info = runners.get(key);
+  info.users++;
+
+  return info.runner;
+}
+
+export function discardRegExpRunner(key: string) {
+  if (!runners.has(key)) {
+    throw new Error(`No runners with key ${key}, cannot discard`);
+  }
+
+  const info = runners.get(key);
+  info.users--;
+
+  if (info.users <= 0) {
+    info.runner.dispose();
+    runners.delete(key);
+  }
+}

backend/src/validatorUtils.ts

@@ -8,23 +8,20 @@ import safeRegex from "safe-regex";
 const regexWithFlags = /^\/(.*?)\/([i]*)$/;
 
 /**
- * The TSafeRegex type supports two syntaxes for regexes: /<regex>/<flags> and just <regex>
- * The value is then checked for "catastrophic exponential-time regular expressions" by
- * https://www.npmjs.com/package/safe-regex
+ * This function supports two input syntaxes for regexes: /<pattern>/<flags> and just <pattern>
  */
-const safeRegexAllowedFlags = ["i"];
-export const TSafeRegex = new t.Type<RegExp, string>(
-  "TSafeRegex",
+export function inputPatternToRegExp(pattern: string) {
+  const advancedSyntaxMatch = pattern.match(regexWithFlags);
+  const [finalPattern, flags] = advancedSyntaxMatch ? [advancedSyntaxMatch[1], advancedSyntaxMatch[2]] : [pattern, ""];
+  return new RegExp(finalPattern, flags);
+}
+
+export const TRegex = new t.Type<RegExp, string>(
+  "TRegex",
   (s): s is RegExp => s instanceof RegExp,
   (from, to) =>
     either.chain(t.string.validate(from, to), s => {
-      const advancedSyntaxMatch = s.match(regexWithFlags);
-      const [regexStr, flags] = advancedSyntaxMatch ? [advancedSyntaxMatch[1], advancedSyntaxMatch[2]] : [s, ""];
-      const finalFlags = flags
-        .split("")
-        .filter(flag => safeRegexAllowedFlags.includes(flag))
-        .join("");
-      return safeRegex(regexStr) ? t.success(new RegExp(regexStr, finalFlags)) : t.failure(from, to, "Unsafe regex");
+      return t.success(inputPatternToRegExp(s));
     }),
   s => `/${s.source}/${s.flags}`,
 );