Add a redact command

README.md

@@ -15,7 +15,7 @@ Phase 1:
 Phase 2:
 * [x] Pantalaimon support
 * [x] No-op mode (for verifying behaviour)
-* [ ] Redact messages on ban (optionally)
+* [x] Redact messages on ban (optionally)
 * [x] More useful spam in management room
 * [ ] Command to import ACLs, etc from rooms
 * [x] Vet rooms on startup option

src/commands/CommandHandler.ts

@@ -24,6 +24,7 @@ import { execSyncCommand } from "./SyncCommand";
 import { execPermissionCheckCommand } from "./PermissionCheckCommand";
 import { execCreateListCommand } from "./CreateBanListCommand";
 import { execUnwatchCommand, execWatchCommand } from "./WatchUnwatchCommand";
+import { execRedactCommand } from "./RedactCommand";
 
 export const COMMAND_PREFIX = "!mjolnir";
 
@@ -50,6 +51,8 @@ export async function handleCommand(roomId: string, event: any, mjolnir: Mjolnir
             return await execWatchCommand(roomId, event, mjolnir, parts);
         } else if (parts[1] === 'unwatch' && parts.length > 1) {
             return await execUnwatchCommand(roomId, event, mjolnir, parts);
+        } else if (parts[1] === 'redact' && parts.length > 1) {
+            return await execRedactCommand(roomId, event, mjolnir, parts);
         } else {
             // Help menu
             const menu = "" +
@@ -57,6 +60,7 @@ export async function handleCommand(roomId: string, event: any, mjolnir: Mjolnir
                 "!mjolnir status                                                     - Print status information\n" +
                 "!mjolnir ban <list_shortcode> <user|room|server> <glob> [reason]    - Adds an entity to the ban list\n" +
                 "!mjolnir unban <list_shortcode> <user|room|server> <glob>           - Removes an entity from the ban list\n" +
+                "!mjolnir redact <user_id> [room alias/ID]                           - Redacts messages by the sender in the target room (or all rooms)\n" +
                 "!mjolnir rules                                                      - Lists the rules currently in use by Mjolnir\n" +
                 "!mjolnir sync                                                       - Force updates of all lists and re-apply rules\n" +
                 "!mjolnir verify                                                     - Ensures Mjolnir can moderate all your rooms\n" +

src/commands/RedactCommand.ts

@@ -0,0 +1,47 @@
+/*
+Copyright 2019 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 { Mjolnir } from "../Mjolnir";
+import { getMessagesByUserSinceLastJoin } from "../utils";
+import config from "../config";
+
+// !mjolnir redact <user ID> [room alias]
+export async function execRedactCommand(roomId: string, event: any, mjolnir: Mjolnir, parts: string[]) {
+    const userId = parts[2];
+    let roomAlias = null;
+    if (parts.length > 3) {
+        roomAlias = await mjolnir.client.resolveRoom(parts[3]);
+    }
+
+    const targetRoomIds = roomAlias ? [roomAlias] : Object.keys(mjolnir.protectedRooms);
+    for (const targetRoomId of targetRoomIds) {
+        if (config.verboseLogging) {
+            await mjolnir.client.sendNotice(mjolnir.managementRoomId, `Fetching sent messages for ${userId} in ${targetRoomId} to redact...`);
+        }
+
+        const eventsToRedact = await getMessagesByUserSinceLastJoin(mjolnir.client, userId, targetRoomId);
+        for (const event of eventsToRedact) {
+            if (config.verboseLogging) {
+                await mjolnir.client.sendNotice(mjolnir.managementRoomId, `Redacting ${event['event_id']} in ${targetRoomId}`);
+            }
+            if (!config.noop) {
+                await mjolnir.client.redactEvent(targetRoomId, event['event_id']);
+            }
+        }
+    }
+
+    await mjolnir.client.unstableApis.addReactionToEvent(roomId, event['event_id'], '✅');
+}

src/utils.ts

@@ -14,6 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+import { MatrixClient } from "matrix-bot-sdk";
+
 export function setToArray<T>(set: Set<T>): T[] {
     const arr: T[] = [];
     for (const v of set) {
@@ -21,3 +23,87 @@ export function setToArray<T>(set: Set<T>): T[] {
     }
     return arr;
 }
+
+export async function getMessagesByUserSinceLastJoin(client: MatrixClient, sender: string, roomId: string): Promise<any[]> {
+    const filter = {
+        room: {
+            rooms: [roomId],
+            state: {
+                types: ["m.room.member"],
+                rooms: [roomId],
+            },
+            timeline: {
+                senders: [sender],
+                rooms: [roomId],
+            },
+            ephemeral: {
+                limit: 0,
+                types: [],
+            },
+            account_data: {
+                limit: 0,
+                types: [],
+            },
+        },
+        presence: {
+            limit: 0,
+            types: [],
+        },
+        account_data: {
+            limit: 0,
+            types: [],
+        },
+    };
+
+    function initialSync() {
+        const qs = {
+            filter: JSON.stringify(filter),
+        };
+        return client.doRequest("GET", "/_matrix/client/r0/sync", qs);
+    }
+
+    function backfill(from: string) {
+        const qs = {
+            filter: JSON.stringify(filter),
+            from: from,
+            dir: "b",
+        };
+        return client.doRequest("GET", `/_matrix/client/r0/rooms/${encodeURIComponent(roomId)}/messages`, qs);
+    }
+
+    // Do an initial sync first to get the batch token
+    const response = await initialSync();
+    if (!response) return [];
+
+    let token = response['next_batch'];
+
+    const messages = [];
+
+    const timeline = (((response['rooms'] || {})['join'] || {})[roomId] || {})['timeline'] || {};
+    const syncedMessages = timeline['events'] || [];
+    token = timeline['prev_batch'] || token;
+    for (const event of syncedMessages) {
+        if (event['sender'] === sender) messages.push(event);
+        if (event['type'] === 'm.room.member' && event['state_key'] === sender) {
+            if (event['content'] && event['content']['membership'] === 'join') {
+                return messages; // we're done!
+            }
+        }
+    }
+
+    while (token) {
+        const bfMessages = await backfill(token);
+        token = bfMessages['end'];
+
+        for (const event of (bfMessages['chunk'] || [])) {
+            if (event['sender'] === sender) messages.push(event);
+            if (event['type'] === 'm.room.member' && event['state_key'] === sender) {
+                if (event['content'] && event['content']['membership'] === 'join') {
+                    return messages; // we're done!
+                }
+            }
+        }
+    }
+
+    return messages;
+}