fix: ensure binary events can handle no content-type header (#134)

* fix: ensure binary events can handle no content-type header

The fix provided in #118
only included tests for `receiver.check()`, and the change in that
case was to add the `application/json` content type to the cleansed
headers if to type was specified.

However, `receiver.parse()` did not receive the benefit of this change. It
calls `this.check()` but then sanitizes the original headers again, and the
missing content-type was not re-inserted into the newly sanitized headers.

This commit, modifies the code so that `receiver.check()` does not insert
the content-type, but does allow the validation check to pass if no
content-type header exists. When `receiver.parse()` is called, and the
headers are sanitized again - and this time used to look up parser implementation,
the default `application/json` content-is applied if no content-type header
exists.

I've also removed a redundant call to `receiver.check()` in receiver_binary_1.js
and simplified the usage of `Constants` in the test.

Signed-off-by: Lance Ball <lball@redhat.com>

* chore: clean up header sniffing

Signed-off-by: Lance Ball <lball@redhat.com>

lib/bindings/http/receiver_binary.js

@@ -1,4 +1,5 @@
-const Constants = require("./constants.js");
+const { HEADER_CONTENT_TYPE, MIME_JSON, DEFAULT_SPEC_VERSION_HEADER } =
+  require("./constants.js");
 const Commons = require("./commons.js");
 const CloudEvent = require("../../cloudevent.js");
 
@@ -52,16 +53,13 @@ BinaryHTTPReceiver.prototype.check = function(payload, headers) {
   // Clone and low case all headers names
   const sanityHeaders = Commons.sanityAndClone(headers);
 
-  // If no content type is provided, default to application/json
-  if (!sanityHeaders[Constants.HEADER_CONTENT_TYPE]) {
-    sanityHeaders[Constants.HEADER_CONTENT_TYPE] = Constants.MIME_JSON;
-  }
-
-  // Validation Level 1
-  if (!this.allowedContentTypes
-    .includes(sanityHeaders[Constants.HEADER_CONTENT_TYPE])) {
+  // Validation Level 1 - if content-type exists, be sure it's
+  // an allowed type
+  const contentTypeHeader = sanityHeaders[HEADER_CONTENT_TYPE];
+  const noContentType = !this.allowedContentTypes.includes(contentTypeHeader);
+  if (contentTypeHeader && noContentType) {
     const err = new TypeError("invalid content type");
-    err.errors = [sanityHeaders[Constants.HEADER_CONTENT_TYPE]];
+    err.errors = [sanityHeaders[HEADER_CONTENT_TYPE]];
     throw err;
   }
 
@@ -71,10 +69,10 @@ BinaryHTTPReceiver.prototype.check = function(payload, headers) {
       throw new TypeError(`header '${required}' not found`);
     });
 
-  if (sanityHeaders[Constants.DEFAULT_SPEC_VERSION_HEADER] !==
+  if (sanityHeaders[DEFAULT_SPEC_VERSION_HEADER] !==
     this.specversion) {
     const err = new TypeError("invalid spec version");
-    err.errors = [sanityHeaders[Constants.DEFAULT_SPEC_VERSION_HEADER]];
+    err.errors = [sanityHeaders[DEFAULT_SPEC_VERSION_HEADER]];
     throw err;
   }
 
@@ -83,14 +81,17 @@ BinaryHTTPReceiver.prototype.check = function(payload, headers) {
 
 function parserFor(parsersByEncoding, cloudevent, headers) {
   const encoding = cloudevent.spec.payload.datacontentencoding;
-  return parsersByEncoding[encoding][headers[Constants.HEADER_CONTENT_TYPE]];
+  return parsersByEncoding[encoding][headers[HEADER_CONTENT_TYPE]];
 }
 
 BinaryHTTPReceiver.prototype.parse = function(payload, headers) {
   this.check(payload, headers);
 
   // Clone and low case all headers names
   const sanityHeaders = Commons.sanityAndClone(headers);
+  if (!sanityHeaders[HEADER_CONTENT_TYPE]) {
+    sanityHeaders[HEADER_CONTENT_TYPE] = MIME_JSON;
+  }
 
   const processedHeaders = [];
   const cloudevent = new CloudEvent(this.Spec);

lib/bindings/http/receiver_binary_1.js

@@ -101,9 +101,6 @@ Receiver.prototype.check = function(payload, headers) {
 };
 
 Receiver.prototype.parse = function(payload, headers) {
-  // firstly specific local checks
-  this.check(payload, headers);
-
   payload = isString(payload) && isBase64(payload)
     ? Buffer.from(payload, "base64").toString()
     : payload;

test/bindings/http/promiscuous_receiver_test.js

@@ -1,6 +1,13 @@
 const { expect } = require("chai");
 const { CloudEvent, HTTPReceiver } = require("../../../index.js");
-const constants = require("../../../lib/bindings/http/constants.js");
+const {
+  HEADER_CONTENT_TYPE,
+  DEFAULT_CONTENT_TYPE,
+  MIME_CE_JSON,
+  DEFAULT_SPEC_VERSION_HEADER,
+  BINARY_HEADERS_03,
+  BINARY_HEADERS_1
+} = require("../../../lib/bindings/http/constants.js");
 
 const receiver = new HTTPReceiver();
 const id = "1234";
@@ -24,7 +31,7 @@ describe("HTTP Transport Binding Receiver for CloudEvents", () => {
       };
 
       const headers = {
-        [constants.HEADER_CONTENT_TYPE]: constants.MIME_CE_JSON
+        [HEADER_CONTENT_TYPE]: MIME_CE_JSON
       };
 
       const event = receiver.accept(headers, payload);
@@ -33,11 +40,11 @@ describe("HTTP Transport Binding Receiver for CloudEvents", () => {
 
     it("Binary data returns a CloudEvent", () => {
       const headers = {
-        [constants.HEADER_CONTENT_TYPE]: constants.DEFAULT_CONTENT_TYPE,
-        [constants.DEFAULT_SPEC_VERSION_HEADER]: specversion,
-        [constants.BINARY_HEADERS_1.ID]: id,
-        [constants.BINARY_HEADERS_1.TYPE]: type,
-        [constants.BINARY_HEADERS_1.SOURCE]: source
+        [HEADER_CONTENT_TYPE]: DEFAULT_CONTENT_TYPE,
+        [DEFAULT_SPEC_VERSION_HEADER]: specversion,
+        [BINARY_HEADERS_1.ID]: id,
+        [BINARY_HEADERS_1.TYPE]: type,
+        [BINARY_HEADERS_1.SOURCE]: source
       };
 
       const event = receiver.accept(headers, data);
@@ -58,7 +65,7 @@ describe("HTTP Transport Binding Receiver for CloudEvents", () => {
       };
 
       const headers = {
-        [constants.HEADER_CONTENT_TYPE]: constants.MIME_CE_JSON
+        [HEADER_CONTENT_TYPE]: MIME_CE_JSON
       };
 
       const event = receiver.accept(headers, payload);
@@ -67,17 +74,53 @@ describe("HTTP Transport Binding Receiver for CloudEvents", () => {
 
     it("Binary data returns a CloudEvent", () => {
       const headers = {
-        [constants.HEADER_CONTENT_TYPE]: constants.DEFAULT_CONTENT_TYPE,
-        [constants.DEFAULT_SPEC_VERSION_HEADER]: specversion,
-        [constants.BINARY_HEADERS_03.ID]: id,
-        [constants.BINARY_HEADERS_03.TYPE]: type,
-        [constants.BINARY_HEADERS_03.SOURCE]: source
+        [HEADER_CONTENT_TYPE]: DEFAULT_CONTENT_TYPE,
+        [DEFAULT_SPEC_VERSION_HEADER]: specversion,
+        [BINARY_HEADERS_03.ID]: id,
+        [BINARY_HEADERS_03.TYPE]: type,
+        [BINARY_HEADERS_03.SOURCE]: source
       };
 
       const event = receiver.accept(headers, data);
       validateEvent(event, specversion);
     });
   });
+
+  describe("Kafka-Knative event source", () => {
+    const specversion = "1.0";
+    const id = "partition:1/offset:23";
+    const type = "dev.knative.kafka.event";
+    const source =
+      "/apis/v1/namespaces/kafka/kafkasources/kafka-source#knative-demo-topic";
+
+    it("Should be parsable", () => {
+      const headers = {
+        host: "event-display.kafka.svc.cluster.local",
+        "user-agent": "Go-http-client/1.1",
+        "content-length": "59",
+        "accept-encoding": "gzip",
+        "ce-id": id,
+        "ce-source": source,
+        "ce-specversion": "1.0",
+        "ce-subject": "partition:1#23",
+        "ce-time": "2020-05-07T14:16:30.245Z",
+        "ce-type": type,
+        forwarded: "for=10.131.0.72;proto=http",
+        "k-proxy-request": "activator",
+        "x-envoy-expected-rq-timeout-ms": "600000",
+        "x-forwarded-for": "10.131.0.72, 10.128.2.99",
+        "x-forwarded-proto": "http",
+        "x-request-id": "d3649c1b-a968-40bf-a9da-3e853abc0c8b"
+      };
+      const event = receiver.accept(headers, data);
+      expect(event instanceof CloudEvent).to.equal(true);
+      expect(event.getId()).to.equal(id);
+      expect(event.getType()).to.equal(type);
+      expect(event.getSource()).to.equal(source);
+      expect(event.getData()).to.deep.equal(data);
+      expect(event.getSpecversion()).to.equal(specversion);
+    });
+  });
 });
 
 function validateEvent(event, specversion) {