Fix content-length calculation

Use byte length instead of character length

Author: mredele

src/request.js

@@ -2,6 +2,17 @@ const ReadableStream = require('stream').Readable;
 const accepts = require('accepts');
 const typeis = require('type-is');
 
+function byteLength(str) {
+  // returns the byte length of an utf8 string
+  let s = str.length
+  for (let i=str.length-1; i>=0; i--) {
+    const code = str.charCodeAt(i)
+    if (code > 0x7f && code <= 0x7ff) s++
+    else if (code > 0x7ff && code <= 0xffff) s+=2
+  }
+  return s
+}
+
 /**
  *
  */
@@ -43,7 +54,7 @@ class Request extends ReadableStream {
     this.params = event.pathParameters;
 
     if (!this.get('Content-Length') && event.body) {
-      this.headers['content-length'] = event.body.length;
+      this.headers['content-length'] = byteLength (event.body);
     }
 
     this.protocol = this.get('X-Forwarded-Proto')

src/request.spec.js

@@ -141,11 +141,22 @@ describe('Request object', () => {
   });
 
   it('should handle content-length header if its not provided', () => {
-    delete event.headers['content-length'];
-    delete event.multiValueHeaders['content-length'];
+    delete event.headers['Content-Length'];
+    delete event.multiValueHeaders['Content-Length'];
+    const body = JSON.stringify(requestObject);
+    event.body = body
 
     const request = new Request(event);
-    const body = JSON.stringify(requestObject);
     expect(request.get('content-length')).toBe(body.length);
   })
+
+  it('should handle non-ascii content-length if header is not provided', () => {
+    delete event.headers['Content-Length'];
+    delete event.multiValueHeaders['Content-Length'];
+    const body = JSON.stringify({text:"árvíztűrőtükörfúrógép"});
+    event.body = body
+
+    const request = new Request(event);
+    expect(request.get('content-length')).toBe(41);
+  })
 });