fix: apply Content-Length header when missing

* Certain requests (e.g. GET and DELETE) would fail when they included a body due to missing content-length header. See #147, #106, #130

__tests__/unit.js

@@ -69,6 +69,7 @@ test('mapApiGatewayEventToHttpRequest: with headers', () => {
     path: '/foo',
     headers: {
       'x-foo': 'foo',
+      'Content-Length': Buffer.byteLength('Hello serverless!'),
       'x-apigateway-event': encodeURIComponent(JSON.stringify(r.eventClone)),
       'x-apigateway-context': encodeURIComponent(JSON.stringify(r.context))
     },
@@ -83,6 +84,7 @@ test('mapApiGatewayEventToHttpRequest: without headers', () => {
     method: 'GET',
     path: '/foo',
     headers: {
+      'Content-Length': Buffer.byteLength('Hello serverless!'),
       'x-apigateway-event': encodeURIComponent(JSON.stringify(r.eventClone)),
       'x-apigateway-context': encodeURIComponent(JSON.stringify(r.context))
     },

package.json

@@ -73,10 +73,7 @@
     "examples/*/node_modules"
   ],
   "jest": {
-    "collectCoverageFrom": [
-      "index.js",
-      "middleware.js"
-    ]
+    "collectCoverageFrom": ["src/*"]
   },
   "devDependencies": {
     "@commitlint/config-conventional": "^6.1.0",
@@ -101,7 +98,7 @@
   },
   "scripts": {
     "test": "jest",
-    "test-watch": "jest --watch",
+    "test:watch": "jest --watch",
     "coverage": "jest --coverage",
     "cz": "git-cz",
     "release": "semantic-release",

src/index.js

@@ -21,6 +21,13 @@ const isType = require('type-is')
 function getPathWithQueryStringParams (event) {
   return url.format({ pathname: event.path, query: event.queryStringParameters })
 }
+function getEventBody (event) {
+  return Buffer.from(event.body, event.isBase64Encoded ? 'base64' : 'utf8')
+}
+
+function clone (json) {
+  return JSON.parse(JSON.stringify(json))
+}
 
 function getContentType (params) {
   // only compare mime type; ignore encoding part
@@ -32,11 +39,18 @@ function isContentTypeBinaryMimeType (params) {
 }
 
 function mapApiGatewayEventToHttpRequest (event, context, socketPath) {
-  const headers = event.headers || {} // NOTE: Mutating event.headers; prefer deep clone of event.headers
-  const eventWithoutBody = Object.assign({}, event)
-  delete eventWithoutBody.body
+  const headers = Object.assign({}, event.headers)
+
+  // NOTE: API Gateway is not setting Content-Length header on requests even when they have a body
+  if (event.body && !headers['Content-Length']) {
+    const body = getEventBody(event)
+    headers['Content-Length'] = Buffer.byteLength(body)
+  }
+
+  const clonedEventWithoutBody = clone(event)
+  delete clonedEventWithoutBody.body
 
-  headers['x-apigateway-event'] = encodeURIComponent(JSON.stringify(eventWithoutBody))
+  headers['x-apigateway-event'] = encodeURIComponent(JSON.stringify(clonedEventWithoutBody))
   headers['x-apigateway-context'] = encodeURIComponent(JSON.stringify(context))
 
   return {
@@ -119,13 +133,12 @@ function forwardLibraryErrorResponseToApiGateway (server, error, context) {
 function forwardRequestToNodeServer (server, event, context) {
   try {
     const requestOptions = mapApiGatewayEventToHttpRequest(event, context, getSocketPath(server._socketPathSuffix))
-    const req = http.request(requestOptions, (response, body) => forwardResponseToApiGateway(server, response, context))
+    const req = http.request(requestOptions, (response) => forwardResponseToApiGateway(server, response, context))
+
     if (event.body) {
-      if (event.isBase64Encoded) {
-        event.body = Buffer.from(event.body, 'base64')
-      }
+      const body = getEventBody(event)
 
-      req.write(event.body)
+      req.write(body)
     }
 
     req.on('error', (error) => forwardConnectionErrorResponseToApiGateway(server, error, context))