Introduced a protection which lets the room bans propagate to a defined banlist

src/protections/PropagateRoomBan.ts

@@ -0,0 +1,111 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { StringProtectionSetting } from './ProtectionSettings';
+import { Mjolnir } from '../Mjolnir';
+import { recommendationToStable, RECOMMENDATION_BAN } from '../models/ListRule';
+import { logMessage } from '../LogProxy';
+import { LogLevel } from 'matrix-bot-sdk';
+import { RULE_USER } from '../models/BanList';
+import { Protection } from './IProtection';
+
+export class PropagateRoomBan extends Protection {
+    settings = {
+        banlistShortcode: new StringProtectionSetting(),
+    };
+
+    public get name(): string {
+        return 'PropagateRoomBan';
+    }
+
+    public get description(): string {
+        return (
+            'If a user is banned in a protected room by a room administrator then the ban ' +
+            'will be published to the banlist defined using the banlistShortcode setting.'
+        );
+    }
+
+    public async handleEvent(mjolnir: Mjolnir, roomId: string, event: any): Promise<void> {
+        if (!this.isBanEvent(event)) {
+            // only interested in ban events
+            return;
+        }
+
+        const content = event['content'] || {};
+        const bannedUser = event['state_key'];
+        const banReason = content['reason'] || '<no reason supplied>';
+        const sender = event['sender'];
+        const stateKey = `rule:${bannedUser}`;
+
+        const ruleContent = {
+            entity: bannedUser,
+            recommendation: recommendationToStable(RECOMMENDATION_BAN),
+            reason: banReason,
+        };
+
+        if (this.settings.banlistShortcode.value === '') {
+            await logMessage(
+                LogLevel.WARN,
+                'PropagateRoomBan',
+                `Can not publish to banlist. User ${bannedUser} was banned in ${roomId}, but protection setting banlistShortcode is missing`
+            );
+            return;
+        }
+
+        const banlist = mjolnir.lists.find(
+            (bl) =>
+                bl.listShortcode.toLowerCase() ===
+                this.settings.banlistShortcode.value.toLowerCase()
+        );
+
+        if (!banlist) {
+            await logMessage(
+                LogLevel.WARN,
+                'PropagateRoomBan',
+                `Can not publish to banlist. User ${bannedUser} was banned in ${roomId}, but banlist ${this.settings.banlistShortcode.value} is not found`
+            );
+            return;
+        }
+
+        await mjolnir.client.sendStateEvent(
+            banlist.roomId,
+            RULE_USER,
+            stateKey,
+            ruleContent
+        );
+        await logMessage(
+            LogLevel.INFO,
+            'PropagateRoomBan',
+            `User ${bannedUser} added to banlist ${banlist.listShortcode}, because ${sender} banned him in ${roomId} for: ${banReason}`
+        );
+    }
+
+    private isBanEvent(event: any): boolean {
+        if (event['type'] !== 'm.room.member') {
+            return false;
+        }
+
+        const membership: string = event['content']['membership'];
+        let prevMembership = 'join';
+
+        if (event['unsigned'] && event['unsigned']['prev_content']) {
+            prevMembership =
+                event['unsigned']['prev_content']['membership'] || 'join';
+        }
+
+        return membership === 'ban' && prevMembership !== 'ban';
+    }
+}

src/protections/protections.ts

@@ -21,12 +21,14 @@ import { WordList } from "./WordList";
 import { MessageIsVoice } from "./MessageIsVoice";
 import { MessageIsMedia } from "./MessageIsMedia";
 import { TrustedReporters } from "./TrustedReporters";
+import { PropagateRoomBan } from './PropagateRoomBan';
 
 export const PROTECTIONS: IProtection[] = [
     new FirstMessageIsImage(),
     new BasicFlooding(),
     new WordList(),
     new MessageIsVoice(),
     new MessageIsMedia(),
-    new TrustedReporters()
+    new TrustedReporters(),
+    new PropagateRoomBan()
 ];