Support automatically redacting users for certain ban reasons

config/default.yaml

@@ -57,6 +57,14 @@ noop: false
 # server struggles with /state requests then set this to true.
 fasterMembershipChecks: false
 
+# A case-insensitive list of ban reasons to automatically redact a user's
+# messages for. Typically this is useful to avoid having to type two commands
+# to the bot. Use asterisks to represent globs (ie: "spam*testing" would match
+# "spam for testing" as well as "spamtesting").
+automaticallyRedactForReasons:
+  - "spam"
+  - "advertising"
+
 # A list of rooms to protect (matrix.to URLs)
 protectedRooms:
   - "https://matrix.to/#/#yourroom:example.org"

src/Mjolnir.ts

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import { LogLevel, LogService, MatrixClient, Permalinks } from "matrix-bot-sdk";
+import { LogLevel, LogService, MatrixClient, MatrixGlob, Permalinks } from "matrix-bot-sdk";
 import BanList, { ALL_RULE_TYPES } from "./models/BanList";
 import { applyServerAcls } from "./actions/ApplyAcl";
 import { RoomUpdateError } from "./models/RoomUpdateError";
@@ -42,12 +42,17 @@ export class Mjolnir {
     private currentState: string = STATE_NOT_STARTED;
     private protections: IProtection[] = [];
     private redactionQueue = new AutomaticRedactionQueue();
+    private automaticRedactionReasons: MatrixGlob[] = [];
 
     constructor(
         public readonly client: MatrixClient,
         public readonly protectedRooms: { [roomId: string]: string },
         private banLists: BanList[],
     ) {
+        for (const reason of config.automaticallyRedactForReasons) {
+            this.automaticRedactionReasons.push(new MatrixGlob(reason.toLowerCase()));
+        }
+
         client.on("room.event", this.handleEvent.bind(this));
 
         client.on("room.message", async (roomId, event) => {
@@ -95,6 +100,10 @@ export class Mjolnir {
         return this.redactionQueue;
     }
 
+    public get automaticRedactGlobs(): MatrixGlob[] {
+        return this.automaticRedactionReasons;
+    }
+
     public start() {
         return this.client.start().then(async () => {
             this.currentState = STATE_CHECKING_PERMISSIONS;

src/actions/ApplyBan.ts

@@ -21,6 +21,7 @@ import config from "../config";
 import { logMessage } from "../LogProxy";
 import { LogLevel } from "matrix-bot-sdk";
 import { ERROR_KIND_FATAL, ERROR_KIND_PERMISSION } from "../ErrorCache";
+import { redactUserMessagesIn } from "../utils";
 
 /**
  * Applies the member bans represented by the ban lists to the provided rooms, returning the
@@ -67,6 +68,11 @@ export async function applyUserBans(lists: BanList[], roomIds: string[], mjolnir
                             await logMessage(LogLevel.DEBUG, "ApplyBan", `Banning ${member.userId} in ${roomId} for: ${userRule.reason}`);
 
                             if (!config.noop) {
+                                // Always prioritize redactions above bans
+                                if (mjolnir.automaticRedactGlobs.find(g => g.test(userRule.reason.toLowerCase()))) {
+                                    await redactUserMessagesIn(mjolnir.client, member.userId, [roomId]);
+                                }
+
                                 await mjolnir.client.banUser(member.userId, roomId, userRule.reason);
                             } else {
                                 await logMessage(LogLevel.WARN, "ApplyBan", `Tried to ban ${member.userId} in ${roomId} but Mjolnir is running in no-op mode`);

src/commands/RedactCommand.ts

@@ -15,10 +15,7 @@ limitations under the License.
 */
 
 import { Mjolnir } from "../Mjolnir";
-import { getMessagesByUserSinceLastJoin } from "../utils";
-import config from "../config";
-import { logMessage } from "../LogProxy";
-import { LogLevel } from "matrix-bot-sdk";
+import { redactUserMessagesIn } from "../utils";
 
 // !mjolnir redact <user ID> [room alias]
 export async function execRedactCommand(roomId: string, event: any, mjolnir: Mjolnir, parts: string[]) {
@@ -29,19 +26,7 @@ export async function execRedactCommand(roomId: string, event: any, mjolnir: Mjo
     }
 
     const targetRoomIds = roomAlias ? [roomAlias] : Object.keys(mjolnir.protectedRooms);
-    for (const targetRoomId of targetRoomIds) {
-        await logMessage(LogLevel.DEBUG, "RedactCommand", `Fetching sent messages for ${userId} in ${targetRoomId} to redact...`);
-
-        const eventsToRedact = await getMessagesByUserSinceLastJoin(mjolnir.client, userId, targetRoomId);
-        for (const victimEvent of eventsToRedact) {
-            await logMessage(LogLevel.DEBUG, "RedactCommand", `Redacting ${victimEvent['event_id']} in ${targetRoomId}`);
-            if (!config.noop) {
-                await mjolnir.client.redactEvent(targetRoomId, victimEvent['event_id']);
-            } else {
-                await logMessage(LogLevel.WARN, "RedactCommand", `Tried to redact ${victimEvent['event_id']} in ${targetRoomId} but Mjolnir is running in no-op mode`);
-            }
-        }
-    }
+    await redactUserMessagesIn(mjolnir.client, userId, targetRoomIds);
 
     await mjolnir.client.unstableApis.addReactionToEvent(roomId, event['event_id'], '✅');
 }

src/config.ts

@@ -35,6 +35,7 @@ interface IConfig {
     noop: boolean;
     protectedRooms: string[]; // matrix.to urls
     fasterMembershipChecks: boolean;
+    automaticallyRedactForReasons: string[]; // case-insensitive globs
 
     /**
      * Config options only set at runtime. Try to avoid using the objects

src/utils.ts

@@ -14,7 +14,9 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import { LogService, MatrixClient, MatrixGlob } from "matrix-bot-sdk";
+import { LogLevel, LogService, MatrixClient, MatrixGlob } from "matrix-bot-sdk";
+import { logMessage } from "./LogProxy";
+import config from "./config";
 
 export function setToArray<T>(set: Set<T>): T[] {
     const arr: T[] = [];
@@ -35,6 +37,22 @@ export function isTrueJoinEvent(event: any): boolean {
     return membership === 'join' && prevMembership !== "join";
 }
 
+export async function redactUserMessagesIn(client: MatrixClient, userIdOrGlob: string, targetRoomIds: string[]) {
+    for (const targetRoomId of targetRoomIds) {
+        await logMessage(LogLevel.DEBUG, "utils#redactUserMessagesIn", `Fetching sent messages for ${userIdOrGlob} in ${targetRoomId} to redact...`);
+
+        const eventsToRedact = await getMessagesByUserSinceLastJoin(client, userIdOrGlob, targetRoomId);
+        for (const victimEvent of eventsToRedact) {
+            await logMessage(LogLevel.DEBUG, "utils#redactUserMessagesIn", `Redacting ${victimEvent['event_id']} in ${targetRoomId}`);
+            if (!config.noop) {
+                await client.redactEvent(targetRoomId, victimEvent['event_id']);
+            } else {
+                await logMessage(LogLevel.WARN, "utils#redactUserMessagesIn", `Tried to redact ${victimEvent['event_id']} in ${targetRoomId} but Mjolnir is running in no-op mode`);
+            }
+        }
+    }
+}
+
 /**
  * Gets all the events sent by a user (or users if using wildcards) in a given room ID, since
  * the time they joined.