Add very basic subscription server for Synapse module

config/default.yaml

@@ -82,3 +82,14 @@ protectedRooms:
 # Note: the management room is *excluded* from this condition. Add it to the
 # protected rooms to protect it.
 protectAllJoinedRooms: false
+
+# An optional server for the Synapse Mjolnir plugin to connect to. This is
+# recommended if you're running the Synapse module in a worker environment,
+# particularly if you're running a federation reader.
+#
+# It is not recommended to expose this to the wider internet. Connections
+# are over TCP only.
+banListServer:
+  enabled: false
+  bind: "0.0.0.0"
+  port: 24465

src/config.ts

@@ -1,5 +1,5 @@
 /*
-Copyright 2019 The Matrix.org Foundation C.I.C.
+Copyright 2019, 2020 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.
@@ -38,6 +38,11 @@ interface IConfig {
     fasterMembershipChecks: boolean;
     automaticallyRedactForReasons: string[]; // case-insensitive globs
     protectAllJoinedRooms: boolean;
+    banListServer: {
+        enabled: boolean;
+        bind: string;
+        port: number;
+    };
 
     /**
      * Config options only set at runtime. Try to avoid using the objects

src/index.ts

@@ -30,6 +30,7 @@ import BanList from "./models/BanList";
 import { Mjolnir } from "./Mjolnir";
 import { logMessage } from "./LogProxy";
 import { MembershipEvent } from "matrix-bot-sdk/lib/models/events/MembershipEvent";
+import {BanListServer} from "./server/BanListServer";
 
 config.RUNTIME = {client: null};
 
@@ -94,5 +95,11 @@ LogService.info("index", "Starting bot...");
     await logMessage(LogLevel.INFO, "index", "Mjolnir is starting up. Use !mjolnir to query status.");
 
     const bot = new Mjolnir(client, protectedRooms, banLists);
+
+    if (config.banListServer && config.banListServer.enabled) {
+        const server = new BanListServer(bot);
+        await server.start();
+    }
+
     await bot.start();
 })();

src/models/BanList.ts

@@ -67,6 +67,10 @@ export default class BanList {
         return this.rules.filter(r => r.kind === RULE_ROOM);
     }
 
+    public get allRules(): ListRule[] {
+        return [...this.serverRules, ...this.userRules, ...this.roomRules];
+    }
+
     public async updateList() {
         this.rules = [];
 

src/server/BanListServer.ts

@@ -0,0 +1,46 @@
+/*
+Copyright 2020 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 * as net from "net";
+import {Socket} from "net";
+import config from "../config";
+import {LogService} from "matrix-bot-sdk";
+import {Connection} from "./Connection";
+
+export class BanListServer {
+
+    private connections: Connection[] = [];
+
+    constructor(private mjolnir: Mjolnir) {
+    }
+
+    public async start() {
+        LogService.info("BanListServer", `Starting server on ${config.banListServer.bind}:${config.banListServer.port}`);
+        const server = net.createServer(this.onConnect.bind(this));
+        server.listen(config.banListServer.port, config.banListServer.bind);
+    }
+
+    private onDisconnect(connection: Connection): void {
+        const index = this.connections.indexOf(connection);
+        if (index >= 0) this.connections.splice(index, 1);
+    }
+
+    private onConnect(socket: Socket) {
+        LogService.info("BanListServer", `New client connection from ${socket.address().toString()}`);
+        this.connections.push(new Connection(socket, this.mjolnir, this.onDisconnect.bind(this)));
+    }
+}

src/server/Connection.ts

@@ -0,0 +1,78 @@
+/*
+Copyright 2020 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 {Socket} from "net";
+import {Mjolnir} from "../Mjolnir";
+import {LogService} from "matrix-bot-sdk";
+import BanList from "../models/BanList";
+
+const COMMAND_PREFIX = "|C,";
+const COMMAND_SUFFIX = ",C|";
+const SUBSCRIBE_PREFIX = `${COMMAND_PREFIX}SUBSCRIBE,`;
+const RESET_PREFIX = `${COMMAND_PREFIX}RESET,`;
+const RULE_PREFIX = `${COMMAND_PREFIX}RULE,`;
+
+export class Connection {
+
+    private currentCommand = "";
+    private subscribedRooms: string[] = [];
+
+    constructor(private socket: Socket, private mjolnir: Mjolnir, private disconnectFn: (Socket) => void) {
+        socket.on("data", this.onData.bind(this));
+        socket.on("close", this.onClose.bind(this));
+    }
+
+    private onListUpdate(list: BanList) {
+        if (!this.subscribedRooms.includes(list.roomId)) {
+            return; // Ignore list update
+        }
+
+        this.socket.write(`${RESET_PREFIX}${list.roomId}${COMMAND_SUFFIX}`);
+        for (const rule of list.allRules) {
+            this.socket.write(`${RULE_PREFIX}${rule.kind},${rule.entity}${COMMAND_SUFFIX}`);
+        }
+    }
+
+    private onClose() {
+        this.disconnectFn(this);
+    }
+
+    private onData(b: Buffer) {
+        this.currentCommand += b.toString("ascii");
+
+        // Try and parse the command
+        const commandStart = this.currentCommand.indexOf(COMMAND_PREFIX);
+        if (commandStart < 0) return; // No command yet
+
+        let command = this.currentCommand.slice(commandStart);
+        let idx = command.indexOf(COMMAND_SUFFIX);
+        if (idx < 0) return; // incomplete command
+        command = command.substring(0, idx);
+        this.currentCommand = this.currentCommand.substring(commandStart + command.length);
+
+        LogService.info("Running " + command);
+        if (command.startsWith(SUBSCRIBE_PREFIX)) {
+            const roomId = command.substring(SUBSCRIBE_PREFIX.length, (command.length - COMMAND_SUFFIX.length - 1) + SUBSCRIBE_PREFIX.length);
+            const banList = this.mjolnir.lists.find(i => i.roomId === roomId);
+            if (!banList) {
+                LogService.warn("Connection", `Connection tried to subscribe to unknown ban list ${roomId}`);
+            } else {
+                this.subscribedRooms.push(roomId);
+                this.onListUpdate(banList);
+            }
+        } // else unknown command
+    }
+}