fix: Make CloudEvent data field immutable and enumerable using Object.keys() (#515) (#516)

Signed-off-by: Philip Sanetra <code@psanetra.de>

.gitignore

@@ -91,3 +91,6 @@ typings/
 
 # Package lock
 package-lock.json
+
+# Jetbrains IDE directories
+.idea

examples/express-ex/index.js

@@ -28,11 +28,11 @@ app.post("/", (req, res) => {
     const responseEventMessage = new CloudEvent({
       source: '/',
       type: 'event:response',
-      ...event
+      ...event,
+      data: {
+        hello: 'world'
+      }
     });
-    responseEventMessage.data = {
-      hello: 'world'
-    };
 
     // const message = HTTP.binary(responseEventMessage)
     const message = HTTP.structured(responseEventMessage)

src/event/cloudevent.ts

@@ -9,7 +9,7 @@ import { Emitter } from "..";
 
 import { CloudEventV1 } from "./interfaces";
 import { validateCloudEvent } from "./spec";
-import { ValidationError, isBinary, asBase64, isValidType } from "./validation";
+import { ValidationError, isBinary, asBase64, isValidType, base64AsBinary } from "./validation";
 
 /**
  * An enum representing the CloudEvent specification version
@@ -33,7 +33,7 @@ export class CloudEvent<T = undefined> implements CloudEventV1<T> {
   dataschema?: string;
   subject?: string;
   time?: string;
-  #_data?: T;
+  data?: T;
   data_base64?: string;
 
   // Extensions should not exist as it's own object, but instead
@@ -85,12 +85,21 @@ export class CloudEvent<T = undefined> implements CloudEventV1<T> {
     delete properties.dataschema;
 
     this.data_base64 = properties.data_base64 as string;
+
+    if (this.data_base64) {
+      this.data = base64AsBinary(this.data_base64) as unknown as T;
+    }
+
     delete properties.data_base64;
 
     this.schemaurl = properties.schemaurl as string;
     delete properties.schemaurl;
 
-    this.data = properties.data;
+    if (isBinary(properties.data)) {
+      this.data_base64 = asBase64(properties.data as unknown as Buffer);
+    }
+
+    this.data = typeof properties.data !== "undefined" ? properties.data : this.data;
     delete properties.data;
 
     // sanity checking
@@ -127,17 +136,6 @@ See: https://github.com/cloudevents/spec/blob/v1.0/spec.md#type-system`);
     Object.freeze(this);
   }
 
-  get data(): T | undefined {
-    return this.#_data;
-  }
-
-  set data(value: T | undefined) {
-    if (isBinary(value)) {
-      this.data_base64 = asBase64(value as unknown as Buffer);
-    }
-    this.#_data = value;
-  }
-
   /**
    * Used by JSON.stringify(). The name is confusing, but this method is called by
    * JSON.stringify() when converting this object to JSON.
@@ -147,7 +145,11 @@ See: https://github.com/cloudevents/spec/blob/v1.0/spec.md#type-system`);
   toJSON(): Record<string, unknown> {
     const event = { ...this };
     event.time = new Date(this.time as string).toISOString();
-    event.data = this.#_data;
+
+    if (event.data_base64 && event.data) {
+      delete event.data;
+    }
+
     return event;
   }
 
@@ -230,9 +232,6 @@ See: https://github.com/cloudevents/spec/blob/v1.0/spec.md#type-system`);
     event: CloudEventV1<any>,
     options: Partial<CloudEventV1<any>>,
     strict = true): CloudEvent<any> {
-      if (event instanceof CloudEvent) {
-        event = event.toJSON() as CloudEventV1<any>;
-      }
       return new CloudEvent(Object.assign({}, event, options), strict);
     }
 }

src/event/validation.ts

@@ -8,6 +8,19 @@ import { ErrorObject } from "ajv";
 export type TypeArray = Int8Array | Uint8Array | Int16Array | Uint16Array | 
   Int32Array | Uint32Array | Uint8ClampedArray | Float32Array | Float64Array;
 
+const globalThisPolyfill = (function() {
+  try {
+    return globalThis;
+  }
+  catch (e) {
+    try {
+      return self;
+    }
+    catch (e) {
+      return global;
+    }
+  }
+}());
 
 /**
  * An Error class that will be thrown when a CloudEvent
@@ -86,6 +99,14 @@ export const asBuffer = (value: string | Buffer | TypeArray): Buffer =>
         throw new TypeError("is not buffer or a valid binary");
       })();
 
+export const base64AsBinary = (base64String: string): Uint8Array => {
+  const toBinaryString = (base64Str: string): string => globalThisPolyfill.atob
+    ? globalThisPolyfill.atob(base64Str)
+    : Buffer.from(base64Str, "base64").toString("binary");
+
+  return Uint8Array.from(toBinaryString(base64String), (c) => c.charCodeAt(0));
+};
+
 export const asBase64 = 
 (value: string | Buffer | TypeArray): string => asBuffer(value).toString("base64");
 

src/message/mqtt/index.ts

@@ -4,6 +4,7 @@
 */
 
 import { Binding, Deserializer, CloudEvent, CloudEventV1, CONSTANTS, Message, ValidationError, Headers } from "../..";
+import { base64AsBinary } from "../../event/validation";
 
 export {
   MQTT, MQTTMessageFactory
@@ -50,14 +51,16 @@ const MQTT: Binding = {
  * @implements {Serializer}
  */
 function binary<T>(event: CloudEventV1<T>): MQTTMessage<T> {
-  let properties;
-  if (event instanceof CloudEvent) {
-    properties = event.toJSON();
-  } else {
-    properties = event;
+  const properties = { ...event };
+
+  let body = properties.data as T;
+
+  if (!body && properties.data_base64) {
+    body = base64AsBinary(properties.data_base64) as unknown as T;
   }
-  const body = properties.data as T;
+
   delete properties.data;
+  delete properties.data_base64;
 
   return MQTTMessageFactory(event.datacontenttype as string, properties, body);
 }

test/integration/cloud_event_test.ts

@@ -7,24 +7,39 @@ import path from "path";
 import fs from "fs";
 
 import { expect } from "chai";
-import { CloudEvent, ValidationError, Version } from "../../src";
+import { CloudEvent, CloudEventV1, ValidationError, Version } from "../../src";
 import { asBase64 } from "../../src/event/validation";
 
 const type = "org.cncf.cloudevents.example";
 const source = "http://unit.test";
 const id = "b46cf653-d48a-4b90-8dfa-355c01061361";
 
-const fixture = {
+const fixture = Object.freeze({
   id,
   specversion: Version.V1,
   source,
   type,
-  data: `"some data"`,
-};
+  data: `"some data"`
+});
 
 const imageData = new Uint32Array(fs.readFileSync(path.join(process.cwd(), "test", "integration", "ce.png")));
 const image_base64 = asBase64(imageData);
 
+// Do not replace this with the assignment of a class instance
+// as we just want to test if we can enumerate all explicitly defined fields!
+const cloudEventV1InterfaceFields: (keyof CloudEventV1<unknown>)[] = Object.keys({
+  id: "",
+  type: "",
+  data: undefined,
+  data_base64: "",
+  source: "",
+  time: "",
+  datacontenttype: "",
+  dataschema: "",
+  specversion: "",
+  subject: ""
+} as Required<CloudEventV1<unknown>>);
+
 describe("A CloudEvent", () => {
   it("Can be constructed with a typed Message", () => {
     const ce = new CloudEvent(fixture);
@@ -78,6 +93,58 @@ describe("A CloudEvent", () => {
       new CloudEvent({ ExtensionWithCaps: "extension value", ...fixture });
     }).throw("invalid extension name");
   });
+
+  it("CloudEventV1 interface fields should be enumerable", () => {
+    const classInstanceKeys = Object.keys(new CloudEvent({ ...fixture }));
+
+    for (const key of cloudEventV1InterfaceFields) {
+      expect(classInstanceKeys).to.contain(key);
+    }
+  });
+
+  it("throws TypeError on trying to set any field value", () => {
+    const ce = new CloudEvent({
+      ...fixture,
+      mycustomfield: "initialValue"
+    });
+
+    const keySet = new Set([...cloudEventV1InterfaceFields, ...Object.keys(ce)]);
+
+    expect(keySet).not.to.be.empty;
+
+    for (const cloudEventKey of keySet) {
+      let threw = false;
+
+      try {
+        ce[cloudEventKey] = "newValue";
+      } catch (err) {
+        threw = true;
+        expect(err).to.be.instanceOf(TypeError);
+        expect((err as TypeError).message).to.include("Cannot assign to read only property");
+      }
+
+      if (!threw) {
+        expect.fail(`Assigning a value to ${cloudEventKey} did not throw`);
+      }
+    }
+  });
+
+  describe("toJSON()", () => {
+    it("does not return data field if data_base64 field is set to comply with JSON format spec 3.1.1", () => {
+      const binaryData = new Uint8Array([1,2,3]);
+
+      const ce = new CloudEvent({
+        ...fixture,
+        data: binaryData
+      });
+
+      expect(ce.data).to.be.equal(binaryData);
+
+      const json = ce.toJSON();
+      expect(json.data).to.not.exist;
+      expect(json.data_base64).to.be.equal("AQID");
+    });
+  });
 });
 
 describe("A 1.0 CloudEvent", () => {

test/integration/mqtt_tests.ts

@@ -32,12 +32,12 @@ const ext2Name = "extension2";
 const ext2Value = "acme";
 
 // Binary data as base64
-const dataBinary = Uint32Array.from(JSON.stringify(data), (c) => c.codePointAt(0) as number);
+const dataBinary = Uint8Array.from(JSON.stringify(data), (c) => c.codePointAt(0) as number);
 const data_base64 = asBase64(dataBinary);
 
 // Since the above is a special case (string as binary), let's test
 // with a real binary file one is likely to encounter in the wild
-const imageData = new Uint32Array(fs.readFileSync(path.join(process.cwd(), "test", "integration", "ce.png")));
+const imageData = new Uint8Array(fs.readFileSync(path.join(process.cwd(), "test", "integration", "ce.png")));
 const image_base64 = asBase64(imageData);
 
 const PUBLISH = {"Content Type": "application/json; charset=utf-8"};
@@ -281,14 +281,14 @@ describe("MQTT transport", () => {
 
   it("Converts base64 encoded data to binary when deserializing structured messages", () => {
     const message = MQTT.structured(fixture.cloneWith({ data: imageData, datacontenttype: "image/png" }));
-    const eventDeserialized = MQTT.toEvent(message) as CloudEvent<Uint32Array>;
+    const eventDeserialized = MQTT.toEvent(message) as CloudEvent<Uint8Array>;
     expect(eventDeserialized.data).to.deep.equal(imageData);
     expect(eventDeserialized.data_base64).to.equal(image_base64);
   });
 
   it("Converts base64 encoded data to binary when deserializing binary messages", () => {
     const message = MQTT.binary(fixture.cloneWith({ data: imageData, datacontenttype: "image/png" }));
-    const eventDeserialized = MQTT.toEvent(message) as CloudEvent<Uint32Array>;
+    const eventDeserialized = MQTT.toEvent(message) as CloudEvent<Uint8Array>;
     expect(eventDeserialized.data).to.deep.equal(imageData);
     expect(eventDeserialized.data_base64).to.equal(image_base64);
   });
@@ -302,7 +302,7 @@ describe("MQTT transport", () => {
 
   it("Does not parse binary data from binary messages with content type application/json", () => {
     const message = MQTT.binary(fixture.cloneWith({ data: dataBinary }));
-    const eventDeserialized = MQTT.toEvent(message) as CloudEvent<Uint32Array>;
+    const eventDeserialized = MQTT.toEvent(message) as CloudEvent<Uint8Array>;
     expect(eventDeserialized.data).to.deep.equal(dataBinary);
     expect(eventDeserialized.data_base64).to.equal(data_base64);
   });

test/integration/spec_1_tests.ts

@@ -19,7 +19,7 @@ const data = {
 };
 const subject = "subject-x0";
 
-let cloudevent = new CloudEvent({
+const cloudevent = new CloudEvent({
   specversion: Version.V1,
   id,
   source,
@@ -120,8 +120,8 @@ describe("CloudEvents Spec v1.0", () => {
       });
 
       it("defaut ID create when an empty string", () => {
-        cloudevent = cloudevent.cloneWith({ id: "" });
-        expect(cloudevent.id.length).to.be.greaterThan(0);
+        const testEvent = cloudevent.cloneWith({ id: "" });
+        expect(testEvent.id.length).to.be.greaterThan(0);
       });
     });
 
@@ -160,11 +160,11 @@ describe("CloudEvents Spec v1.0", () => {
     describe("'time'", () => {
       it("must adhere to the format specified in RFC 3339", () => {
         const d = new Date();
-        cloudevent = cloudevent.cloneWith({ time: d.toString() }, false);
+        const testEvent = cloudevent.cloneWith({ time: d.toString() }, false);
         // ensure that we always get back the same thing we passed in
-        expect(cloudevent.time).to.equal(d.toString());
+        expect(testEvent.time).to.equal(d.toString());
         // ensure that when stringified, the timestamp is in RFC3339 format
-        expect(JSON.parse(JSON.stringify(cloudevent)).time).to.equal(new Date(d.toString()).toISOString());
+        expect(JSON.parse(JSON.stringify(testEvent)).time).to.equal(new Date(d.toString()).toISOString());
       });
     });
   });