superagent: fix multipart form-data

src/superagent.js

@@ -82,7 +82,7 @@ class Request {
                 if (error) reject(error); else resolve(result);
             });
 
-            if (this.body) request.write(this.body, 'utf8');
+            if (this.body) request.write(this.body);
 
             request.end();
         });
@@ -134,11 +134,11 @@ class Request {
         const contentType = this.options.headers['content-type'];
         if (!contentType || contentType === 'application/json') {
             this.options.headers['content-type'] = 'application/json';
-            this.body = JSON.stringify(data);
+            this.body = Buffer.from(JSON.stringify(data), 'utf8');
-            this.options.headers['content-length'] = Buffer.byteLength(this.body, 'utf8');
+            this.options.headers['content-length'] = this.body.byteLength;
         } else if (contentType === 'application/x-www-form-urlencoded') {
-            this.body = (new URLSearchParams(data)).toString();
+            this.body = Buffer.from((new URLSearchParams(data)).toString(), 'utf8');
-            this.options.headers['content-length'] = Buffer.byteLength(this.body, 'utf8');
+            this.options.headers['content-length'] = this.body.byteLength;
         }
         return this;
     }
@@ -169,11 +169,17 @@ class Request {
         return this;
     }
 
-    attach(name, filepath) {
+    attach(name, filepath) { // this is only used in tests and thus simplistic
-        if (!(this.options.body instanceof FormData)) this.options.body = new FormData();
+        const boundary = '----WebKitFormBoundary' + Math.random().toString(36).substring(2);
-        const data = fs.readFileSync(filepath);
+
-        this.options.body.append(name, new Blob([data]), path.basename(filepath));
+        const partHeader = Buffer.from(`--${boundary}\r\nContent-Disposition: form-data; name="${name}" filename="${path.basename(filepath)}"\r\n\r\n`, 'utf8');
-        delete this.options.headers['content-type']; // explicitly remove it. without it boundary won't make it to the header!
+        const partData = fs.readFileSync(filepath);
+        const partTrailer = Buffer.from(`\r\n--${boundary}--\r\n`, 'utf8');
+        this.body = Buffer.concat([partHeader, partData, partTrailer]);
+
+        this.options.headers['content-type'] = `multipart/form-data; boundary=${boundary}`;
+        this.options.headers['content-length'] = this.body.byteLength;
+
         return this;
     }