fix: preserve user-defined boundary in multipart/mixed Content-Type header (#7531)

* fix: preserve user-defined boundary in multipart/mixed Content-Type header

When users specify a boundary parameter in their Content-Type header for
multipart/mixed requests with TEXT body mode, Bruno now preserves the
user-defined boundary instead of generating a new one.

Fixes: https://github.com/usebruno/bruno/issues/7523

* updated the test to use local server and changed the request method to GET

* fix: handle quoted boundary values in Content-Type header extraction

---------

Co-authored-by: Chirag Chandrashekhar <cchirag85@gmail.com>

packages/bruno-cli/src/runner/run-single-request.js

@@ -26,7 +26,7 @@ const { addDigestInterceptor, getHttpHttpsAgents, makeAxiosInstance: makeAxiosIn
 const { getCACertificates, transformProxyConfig, getOrCreateHttpsAgent, getOrCreateHttpAgent } = require('@usebruno/requests');
 const { getOAuth2Token, getFormattedOauth2Credentials } = require('../utils/oauth2');
 const tokenStore = require('../store/tokenStore');
-const { encodeUrl, buildFormUrlEncodedPayload, extractPromptVariables, isFormData } = require('@usebruno/common').utils;
+const { encodeUrl, buildFormUrlEncodedPayload, extractPromptVariables, isFormData, extractBoundaryFromContentType } = require('@usebruno/common').utils;
 
 const onConsoleLog = (type, args) => {
   console[type](...args);
@@ -570,7 +570,12 @@ const runSingleRequest = async function (
         if (contentType !== 'multipart/form-data') {
           // Patch: Axios leverages getHeaders method to get the headers so FormData should be monkey patched
           const formHeaders = form.getHeaders();
-          formHeaders['content-type'] = `${contentType}; boundary=${form.getBoundary()}`;
+          const existingBoundary = extractBoundaryFromContentType(contentType);
+          if (existingBoundary) {
+            formHeaders['content-type'] = contentType;
+          } else {
+            formHeaders['content-type'] = `${contentType}; boundary=${form.getBoundary()}`;
+          }
           form.getHeaders = function () {
             return formHeaders;
           };

packages/bruno-common/src/utils/form-data.spec.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from '@jest/globals';
-import { buildFormUrlEncodedPayload, isFormData } from './form-data';
+import { buildFormUrlEncodedPayload, isFormData, extractBoundaryFromContentType } from './form-data';
 import FormData from 'form-data';
 
 describe('buildFormUrlEncodedPayload', () => {
@@ -161,3 +161,51 @@ describe('isFormData', () => {
     expect(isFormData(formData)).toBe(true);
   });
 });
+
+describe('extractBoundaryFromContentType', () => {
+  it('should extract boundary from Content-Type header', () => {
+    expect(extractBoundaryFromContentType('multipart/mixed; boundary=my-boundary')).toBe('my-boundary');
+  });
+
+  it('should extract boundary with dashes', () => {
+    expect(extractBoundaryFromContentType('multipart/mixed; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW')).toBe('----WebKitFormBoundary7MA4YWxkTrZu0gW');
+  });
+
+  it('should extract boundary case-insensitively', () => {
+    expect(extractBoundaryFromContentType('multipart/mixed; BOUNDARY=my-boundary')).toBe('my-boundary');
+    expect(extractBoundaryFromContentType('multipart/mixed; Boundary=my-boundary')).toBe('my-boundary');
+  });
+
+  it('should extract boundary when other params exist', () => {
+    expect(extractBoundaryFromContentType('multipart/mixed; charset=utf-8; boundary=my-boundary')).toBe('my-boundary');
+    expect(extractBoundaryFromContentType('multipart/mixed; boundary=my-boundary; charset=utf-8')).toBe('my-boundary');
+  });
+
+  it('should return null when no boundary exists', () => {
+    expect(extractBoundaryFromContentType('multipart/mixed')).toBeNull();
+    expect(extractBoundaryFromContentType('application/json')).toBeNull();
+  });
+
+  it('should return null for non-string input', () => {
+    expect(extractBoundaryFromContentType(null)).toBeNull();
+    expect(extractBoundaryFromContentType(undefined)).toBeNull();
+    expect(extractBoundaryFromContentType(123)).toBeNull();
+    expect(extractBoundaryFromContentType({})).toBeNull();
+  });
+
+  it('should handle empty string', () => {
+    expect(extractBoundaryFromContentType('')).toBeNull();
+  });
+
+  it('should extract boundary from quoted value', () => {
+    expect(extractBoundaryFromContentType('multipart/mixed; boundary="my-boundary"')).toBe('my-boundary');
+  });
+
+  it('should extract quoted boundary with spaces', () => {
+    expect(extractBoundaryFromContentType('multipart/mixed; boundary="my boundary value"')).toBe('my boundary value');
+  });
+
+  it('should extract quoted boundary when other params exist', () => {
+    expect(extractBoundaryFromContentType('multipart/mixed; charset=utf-8; boundary="my-boundary"')).toBe('my-boundary');
+  });
+});

packages/bruno-common/src/utils/form-data.ts

@@ -43,3 +43,16 @@ export const isFormData = (obj: unknown): boolean => {
   // todo: checking constructor.name can produce false positives for objects that have a constructor.name property set to 'FormData', but this is rare.
   return obj?.constructor?.name === 'FormData';
 };
+
+/**
+ * Extracts boundary parameter from a Content-Type header value.
+ * @param contentType - The Content-Type header value (e.g., "multipart/mixed; boundary=my-boundary")
+ * @returns The boundary value if found, or null if not present
+ */
+export const extractBoundaryFromContentType = (contentType: unknown): string | null => {
+  if (typeof contentType !== 'string') {
+    return null;
+  }
+  const match = contentType.match(/boundary="([^"]+)"|boundary=([^;\s]+)/i);
+  return match ? (match[1] || match[2]) : null;
+};

packages/bruno-common/src/utils/index.ts

@@ -7,7 +7,8 @@ export {
 
 export {
   buildFormUrlEncodedPayload,
-  isFormData
+  isFormData,
+  extractBoundaryFromContentType
 } from './form-data';
 
 export {

packages/bruno-electron/src/ipc/network/index.js

@@ -35,7 +35,7 @@ const { cookiesStore } = require('../../store/cookies');
 const registerGrpcEventHandlers = require('./grpc-event-handlers');
 const { registerWsEventHandlers } = require('./ws-event-handlers');
 const { getCertsAndProxyConfig, buildCertsAndProxyConfig } = require('./cert-utils');
-const { buildFormUrlEncodedPayload, isFormData } = require('@usebruno/common').utils;
+const { buildFormUrlEncodedPayload, isFormData, extractBoundaryFromContentType } = require('@usebruno/common').utils;
 
 const ERROR_OCCURRED_WHILE_EXECUTING_REQUEST = 'Error occurred while executing the request!';
 
@@ -609,7 +609,12 @@ const registerNetworkIpc = (mainWindow) => {
         if (contentType !== 'multipart/form-data') {
           // Patch: Axios leverages getHeaders method to get the headers so FormData should be monkey patched
           const formHeaders = form.getHeaders();
-          formHeaders['content-type'] = `${contentType}; boundary=${form.getBoundary()}`;
+          const existingBoundary = extractBoundaryFromContentType(contentType);
+          if (existingBoundary) {
+            formHeaders['content-type'] = contentType;
+          } else {
+            formHeaders['content-type'] = `${contentType}; boundary=${form.getBoundary()}`;
+          }
           form.getHeaders = function () {
             return formHeaders;
           };

packages/bruno-tests/src/echo/index.js

@@ -5,6 +5,15 @@ router.get('/path/*', (req, res) => {
   return res.json({ url: req.url });
 });
 
+// Echo back request headers - useful for testing header manipulation
+router.all('/headers', (req, res) => {
+  return res.json({
+    method: req.method,
+    headers: req.headers,
+    url: req.url
+  });
+});
+
 router.post('/json', (req, res) => {
   return res.json(req.body);
 });