feat: moderate users with links disabled

This commit will add a new rule to the antispam service that will reject
any message coming from members having the links-disabled role, no
matter where they point to.

package.json

@@ -19,6 +19,7 @@
     "discord.js-commando": "git://github.com/discordjs/Commando.git#198d7604e3725ee88dceab9b5f296edb1b7580a5",
     "dotenv": "^8.2.0",
     "express": "^4.17.1",
+    "get-urls": "^10.0.0",
     "log4js": "^6.3.0",
     "sqlite": "^2.9.3",
     "uws": "^200.0.0",

src/hooks/antispam.ts

@@ -1,4 +1,6 @@
 import { Message } from "discord.js";
+import getUrls from "get-urls";
+
 import Member from "../lib/member";
 import { WastebinModlogEvent } from "../lib/modlog";
 import Server from "../lib/server";
@@ -19,13 +21,32 @@ const ruleset: { [reason: string]: RegExp[] } = {
   ],
 };
 
-function matches(message: string): string | undefined {
+const disabledLinksReason = "el origen está retenido, un mod debería revisar los logs";
+
+function matchesUrlInRuleset(message: string): string | undefined {
   return Object.keys(ruleset).find((rule) => {
     const regexps = ruleset[rule];
     return regexps.some((regexp) => regexp.test(message));
   });
 }
 
+function messageContainsURL(message: string): boolean {
+  return getUrls(message).size > 0;
+}
+
+function testModeration(message: Message): string | undefined {
+  const member = new Member(message.member);
+  const text = normalizeMessageContent(message);
+
+  if (!member.canPostLinks && messageContainsURL(text)) {
+    /* The member cannot post links. */
+    return disabledLinksReason;
+  } else {
+    /* The message may or may not contain a link to an invalid site. */
+    return matchesUrlInRuleset(text);
+  }
+}
+
 function isAllowed(message: Message): boolean {
   if (message.author.bot) {
     return true;
@@ -66,7 +87,7 @@ export default class AntispamService implements Hook {
     if (isAllowed(message)) {
       return; /* trusted member or bot */
     }
-    const match = matches(normalizeMessageContent(message));
+    const match = testModeration(message);
     if (match) {
       const server = new Server(message.guild);
 

src/lib/member.ts

@@ -45,6 +45,10 @@ export default class Member {
     return this.hasRole(this.server.helperRole);
   }
 
+  get canPostLinks(): boolean {
+    return !this.hasRole(this.server.linksDisabledRole);
+  }
+
   get cooldown(): boolean {
     if (!this.guildMember.joinedAt) {
       /* TODO: Investigate why THIS happens. */

src/lib/server.ts

@@ -150,6 +150,11 @@ export default class Server {
     return this.getRoleByName(trustedRoleName);
   }
 
+  get linksDisabledRole(): Role {
+    const linksDisabledRole = process.env.LINKS_DISABLE_ROLE || "links-disabled";
+    return this.getRoleByName(linksDisabledRole);
+  }
+
   get publicModlogChannel(): TextChannel {
     const modlogChannelName = process.env.PUBLIC_MODLOG_CHANNEL || "public-modlog";
     return this.getTextChannelByName(modlogChannelName);