feat(#707): secure Discord service ingress (#716)

apps/gateway/src/plugin/discord-ingress.security.spec.ts

@@ -0,0 +1,89 @@
+import { describe, expect, it } from 'vitest';
+import {
+  createDiscordIngressEnvelope,
+  verifyDiscordIngressEnvelope,
+  type DiscordIngressPayload,
+} from '@mosaicstack/discord-plugin';
+import { validateDiscordServiceToken } from '../chat/chat.gateway-auth.js';
+import { DiscordReplayProtector } from './discord-replay-protector.js';
+
+const SERVICE_TOKEN = 'test-service-token';
+
+function createPayload(overrides: Partial<DiscordIngressPayload> = {}): DiscordIngressPayload {
+  return {
+    correlationId: 'correlation-001',
+    messageId: 'discord-message-001',
+    guildId: 'guild-001',
+    channelId: 'channel-001',
+    userId: 'user-001',
+    conversationId: 'discord-channel-001',
+    content: 'hello Tess',
+    ...overrides,
+  };
+}
+
+describe('Discord ingress security', () => {
+  it('accepts only the configured Discord service identity', () => {
+    expect(validateDiscordServiceToken(SERVICE_TOKEN, SERVICE_TOKEN)).toBe(true);
+    expect(validateDiscordServiceToken('wrong-service-token', SERVICE_TOKEN)).toBe(false);
+    expect(validateDiscordServiceToken(undefined, SERVICE_TOKEN)).toBe(false);
+  });
+
+  it('rejects unauthenticated or tampered service envelopes', () => {
+    const envelope = createDiscordIngressEnvelope(createPayload(), SERVICE_TOKEN);
+
+    expect(verifyDiscordIngressEnvelope(envelope, SERVICE_TOKEN)).toEqual(createPayload());
+    expect(verifyDiscordIngressEnvelope(envelope, 'wrong-service-token')).toBeNull();
+    expect(
+      verifyDiscordIngressEnvelope(
+        { ...envelope, payload: { ...envelope.payload, content: 'forged command' } },
+        SERVICE_TOKEN,
+      ),
+    ).toBeNull();
+  });
+
+  it.each([
+    ['guild', { guildId: 'unlisted-guild' }],
+    ['channel', { channelId: 'unlisted-channel' }],
+    ['user', { userId: 'unlisted-user' }],
+  ])(
+    'rejects an unallowlisted Discord %s',
+    (_kind: string, overrides: Partial<DiscordIngressPayload>) => {
+      const envelope = createDiscordIngressEnvelope(createPayload(overrides), SERVICE_TOKEN);
+
+      expect(
+        verifyDiscordIngressEnvelope(envelope, SERVICE_TOKEN, {
+          guildIds: ['guild-001'],
+          channelIds: ['channel-001'],
+          userIds: ['user-001'],
+        }),
+      ).toBeNull();
+    },
+  );
+
+  it('retains Discord message and correlation IDs after authenticated allowlisted validation', () => {
+    const payload = createPayload({
+      correlationId: 'correlation-trace-123',
+      messageId: 'discord-snowflake-987',
+    });
+    const envelope = createDiscordIngressEnvelope(payload, SERVICE_TOKEN);
+
+    expect(
+      verifyDiscordIngressEnvelope(envelope, SERVICE_TOKEN, {
+        guildIds: ['guild-001'],
+        channelIds: ['channel-001'],
+        userIds: ['user-001'],
+      }),
+    ).toEqual(payload);
+  });
+
+  it('rejects a replayed Discord message ID while retaining bounded replay state', () => {
+    const replayProtector = new DiscordReplayProtector(60_000, 2);
+
+    expect(replayProtector.claim('discord-message-001')).toBe(true);
+    expect(replayProtector.claim('discord-message-001')).toBe(false);
+    expect(replayProtector.claim('discord-message-002')).toBe(true);
+    expect(replayProtector.claim('discord-message-003')).toBe(true);
+    expect(replayProtector.size).toBe(2);
+  });
+});

apps/gateway/src/plugin/discord-replay-protector.ts

@@ -0,0 +1,40 @@
+/**
+ * Bounded replay cache for Discord's globally unique native message IDs.
+ * Durable ingress idempotency is added with Tess's canonical inbox/outbox work.
+ */
+export class DiscordReplayProtector {
+  private readonly claimedAt = new Map<string, number>();
+
+  constructor(
+    private readonly ttlMs = 15 * 60 * 1000,
+    private readonly maxEntries = 10_000,
+  ) {}
+
+  get size(): number {
+    return this.claimedAt.size;
+  }
+
+  /** Claims an ID exactly once within its bounded retention window. */
+  claim(messageId: string, now = Date.now()): boolean {
+    this.prune(now);
+    if (this.claimedAt.has(messageId)) return false;
+
+    this.claimedAt.set(messageId, now);
+    this.evictOverflow();
+    return true;
+  }
+
+  private prune(now: number): void {
+    for (const [messageId, claimedAt] of this.claimedAt) {
+      if (now - claimedAt >= this.ttlMs) this.claimedAt.delete(messageId);
+    }
+  }
+
+  private evictOverflow(): void {
+    while (this.claimedAt.size > this.maxEntries) {
+      const oldestMessageId = this.claimedAt.keys().next().value;
+      if (oldestMessageId === undefined) return;
+      this.claimedAt.delete(oldestMessageId);
+    }
+  }
+}

apps/gateway/src/plugin/plugin.module.ts

@@ -50,19 +50,41 @@ class TelegramChannelPluginAdapter implements IChannelPlugin {
 
 const DEFAULT_GATEWAY_URL = 'http://localhost:14242';
 
+function requiredDiscordAllowlist(name: string): string[] {
+  const value = process.env[name]
+    ?.split(',')
+    .map((id: string): string => id.trim())
+    .filter((id: string): boolean => id.length > 0);
+  if (!value || value.length === 0) {
+    throw new Error(`${name} is required when DISCORD_BOT_TOKEN is configured`);
+  }
+  return value;
+}
+
 function createPluginRegistry(): IChannelPlugin[] {
   const plugins: IChannelPlugin[] = [];
   const discordToken = process.env['DISCORD_BOT_TOKEN'];
   const discordGuildId = process.env['DISCORD_GUILD_ID'];
   const discordGatewayUrl = process.env['DISCORD_GATEWAY_URL'] ?? DEFAULT_GATEWAY_URL;
+  const discordServiceToken = process.env['DISCORD_SERVICE_TOKEN'];
+  const discordServiceUserId = process.env['DISCORD_SERVICE_USER_ID'];
 
   if (discordToken) {
+    if (!discordServiceToken || !discordServiceUserId) {
+      throw new Error(
+        'DISCORD_SERVICE_TOKEN and DISCORD_SERVICE_USER_ID are required when DISCORD_BOT_TOKEN is configured',
+      );
+    }
     plugins.push(
       new DiscordChannelPluginAdapter(
         new DiscordPlugin({
           token: discordToken,
           guildId: discordGuildId,
           gatewayUrl: discordGatewayUrl,
+          serviceToken: discordServiceToken,
+          allowedGuildIds: requiredDiscordAllowlist('DISCORD_ALLOWED_GUILD_IDS'),
+          allowedChannelIds: requiredDiscordAllowlist('DISCORD_ALLOWED_CHANNEL_IDS'),
+          allowedUserIds: requiredDiscordAllowlist('DISCORD_ALLOWED_USER_IDS'),
         }),
       ),
     );