feat: reject events with long content field

Signed-off-by: Ricardo Arturo Cabral Mejía <me@ricardocabral.io>

src/handlers/event-message-handler.ts

@@ -63,6 +63,10 @@ export class EventMessageHandler implements IMessageHandler {
   protected canAcceptEvent(event: Event): string | undefined {
     const now = Math.floor(Date.now()/1000)
     const limits = this.settings().limits.event
+    if (limits.content?.maxLength > 0 && event.content.length > limits.content.maxLength) {
+      return `rejected: content is longer than ${limits.content.maxLength} bytes`
+    }
+
     if (limits.createdAt.maxPositiveDelta > 0 && event.created_at > now + limits.createdAt.maxPositiveDelta) {
       return `rejected: created_at is more than ${limits.createdAt.maxPositiveDelta} seconds in the future`
     }

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

@@ -177,6 +177,9 @@ describe('EventMessageHandler', () => {
           blacklist: [],
           whitelist: [],
         },
+        content: {
+          maxLength: 0,
+        },
       }
       settings = {
         limits: {
@@ -235,6 +238,55 @@ describe('EventMessageHandler', () => {
       })
     })
 
+    describe('content', () => {
+      describe('maxLength', () => {
+        it('returns undefined if maxLength is zero', () => {
+          eventLimits.content.maxLength = 0
+
+          expect(
+            (handler as any).canAcceptEvent(event)
+          ).to.be.undefined
+        })
+
+        it('returns undefned if content is not too long', () => {
+          eventLimits.content.maxLength = 100
+          event.content = 'x'.repeat(100)
+
+          expect(
+            (handler as any).canAcceptEvent(event)
+          ).to.be.undefined
+        })
+
+        it('returns reason if content is too long', () => {
+          eventLimits.content.maxLength = 100
+          event.content = 'x'.repeat(101)
+
+          expect(
+            (handler as any).canAcceptEvent(event)
+          ).to.equal('rejected: content is longer than 100 bytes')
+        })
+      })
+
+      describe('maxNegativeDelta', () => {
+        it('returns undefined if maxNegativeDelta is zero', () => {
+          eventLimits.createdAt.maxNegativeDelta = 0
+
+          expect(
+            (handler as any).canAcceptEvent(event)
+          ).to.be.undefined
+        })
+
+        it('returns reason if createdDate is too far in the past', () => {
+          eventLimits.createdAt.maxNegativeDelta = 100
+          event.created_at -= 101
+
+          expect(
+            (handler as any).canAcceptEvent(event)
+          ).to.equal('rejected: created_at is more than 100 seconds in the past')
+        })
+      })
+    })
+
     describe('eventId', () => {
       describe('minLeadingZeroBits', () => {
         it('returns undefined if minLeadingZeroBits is zero', () => {