feat: reject NIP-70 protected events

.changeset/nip70-reject-protected-events.md

@@ -0,0 +1,5 @@
+---
+"nostream": minor
+---
+
+feat: reject NIP-70 protected events and reposts embedding them

src/handlers/event-message-handler.ts

@@ -1,4 +1,4 @@
-import { ContextMetadataKey, EventExpirationTimeMetadataKey, EventKinds } from '../constants/base'
+import { ContextMetadataKey, EventExpirationTimeMetadataKey, EventKinds, EventTags } from '../constants/base'
 import {
   DEFAULT_NIP05_VERIFY_EXPIRATION_MS,
   extractNip05FromEvent,
@@ -21,6 +21,7 @@ import {
   isEventSignatureValid,
   isExpiredEvent,
   isFileMessageEvent,
+  isProtectedEvent,
   isRequestToVanishEvent,
   isSealEvent,
   isWelcomeRumorEvent,
@@ -88,6 +89,13 @@ export class EventMessageHandler implements IMessageHandler {
       return
     }
 
+    reason = this.isProtectedEventBlocked(event)
+    if (reason) {
+      logger('event %s rejected: %s', event.id, reason)
+      this.webSocket.emit(WebSocketAdapterEvent.Message, createCommandResult(event.id, false, reason))
+      return
+    }
+
     reason = await this.isBlockedByRequestToVanish(event)
     if (reason) {
       logger('event %s rejected: %s', event.id, reason)
@@ -224,6 +232,26 @@ export class EventMessageHandler implements IMessageHandler {
     }
   }
 
+  protected isProtectedEventBlocked(event: Event): string | undefined {
+    if (isProtectedEvent(event)) {
+      return 'auth-required: this event may only be published by its author'
+    }
+
+    if (event.kind === EventKinds.REPOST && event.content.length > 0) {
+      try {
+        const embedded = JSON.parse(event.content)
+        if (
+          Array.isArray(embedded?.tags) &&
+          embedded.tags.some((tag: string[]) => Array.isArray(tag) && tag[0] === EventTags.Protected)
+        ) {
+          return 'blocked: reposts must not embed protected events'
+        }
+      } catch (_e) {
+        // Ignore invalid JSON: repost content is not a valid embedded event
+      }
+    }
+  }
+
   protected async isEventValid(event: Event): Promise<string | undefined> {
     if (!(await isEventIdValid(event))) {
       return 'invalid: event id does not match'

test/unit/handlers/event-message-handler.spec.ts

@@ -2120,4 +2120,116 @@ describe('EventMessageHandler', () => {
       expect(nip05VerificationRepository.upsert).to.have.been.calledOnce
     })
   })
+
+  describe('isProtectedEventBlocked', () => {
+    beforeEach(() => {
+      handler = new EventMessageHandler(
+        {} as any,
+        () => null,
+        {} as any,
+        userRepository,
+        () =>
+          ({
+            info: { relay_url: 'relay_url' },
+          }) as any,
+        {} as any,
+        { hasKey: async () => false, setKey: async () => true } as any,
+        () => ({ hit: async () => false }),
+      )
+    })
+
+    it('returns reason if event has a protected tag', () => {
+      event.tags = [['-']] as any
+      expect((handler as any).isProtectedEventBlocked(event)).to.equal(
+        'auth-required: this event may only be published by its author',
+      )
+    })
+
+    it('returns undefined if event has no protected tag', () => {
+      event.tags = [['e', 'abc']]
+      expect((handler as any).isProtectedEventBlocked(event)).to.be.undefined
+    })
+
+    it('returns undefined if event has no tags', () => {
+      event.tags = []
+      expect((handler as any).isProtectedEventBlocked(event)).to.be.undefined
+    })
+
+    it('returns reason if kind 6 repost embeds a protected event', () => {
+      event.kind = EventKinds.REPOST
+      event.content = JSON.stringify({
+        id: 'a'.repeat(64),
+        pubkey: 'b'.repeat(64),
+        kind: 1,
+        tags: [['-']],
+        content: 'secret',
+        sig: 'c'.repeat(128),
+        created_at: 1000,
+      })
+      event.tags = []
+      expect((handler as any).isProtectedEventBlocked(event)).to.equal(
+        'blocked: reposts must not embed protected events',
+      )
+    })
+
+    it('returns undefined if kind 6 repost embeds a non-protected event', () => {
+      event.kind = EventKinds.REPOST
+      event.content = JSON.stringify({
+        id: 'a'.repeat(64),
+        pubkey: 'b'.repeat(64),
+        kind: 1,
+        tags: [],
+        content: 'public',
+        sig: 'c'.repeat(128),
+        created_at: 1000,
+      })
+      event.tags = []
+      expect((handler as any).isProtectedEventBlocked(event)).to.be.undefined
+    })
+
+    it('returns undefined if kind 6 repost has empty content', () => {
+      event.kind = EventKinds.REPOST
+      event.content = ''
+      event.tags = []
+      expect((handler as any).isProtectedEventBlocked(event)).to.be.undefined
+    })
+
+    it('returns undefined if kind 6 repost has invalid JSON content', () => {
+      event.kind = EventKinds.REPOST
+      event.content = 'not json'
+      event.tags = []
+      expect((handler as any).isProtectedEventBlocked(event)).to.be.undefined
+    })
+
+    it('returns undefined for non-repost event kinds with JSON content', () => {
+      event.kind = EventKinds.TEXT_NOTE
+      event.content = JSON.stringify({ tags: [['-']] })
+      event.tags = []
+      expect((handler as any).isProtectedEventBlocked(event)).to.be.undefined
+    })
+
+    it('rejects on the protected tag before checking embedded repost content', () => {
+      event.kind = EventKinds.REPOST
+      event.content = JSON.stringify({
+        id: 'a'.repeat(64),
+        pubkey: 'b'.repeat(64),
+        kind: 1,
+        tags: [['-']],
+        content: 'secret',
+        sig: 'c'.repeat(128),
+        created_at: 1000,
+      })
+      event.tags = [['-']] as any
+      expect((handler as any).isProtectedEventBlocked(event)).to.equal(
+        'auth-required: this event may only be published by its author',
+      )
+    })
+
+    it('returns undefined if kind 6 repost has non-array embedded tags', () => {
+      event.kind = EventKinds.REPOST
+      event.content = JSON.stringify({ tags: 'not-an-array' })
+      event.tags = []
+      expect((handler as any).isProtectedEventBlocked(event)).to.be.undefined
+    })
+  })
 })