[Fix] validate boundary type in setBoundary() method

Mallikarjun-0 · ljharb · commit 131ae5efa30b · 2025-04-12T20:13:44.000+05:30
diff --git a/lib/form_data.js b/lib/form_data.js
@@ -315,6 +315,13 @@ FormData.prototype.getHeaders = function (userHeaders) {
   return formHeaders;
 };
 
+FormData.prototype.setBoundary = function (boundary) {
+  if (typeof boundary !== 'string') {
+    throw new TypeError('FormData boundary must be a string');
+  }
+  this._boundary = boundary;
+};
+
 FormData.prototype.getBoundary = function () {
   if (!this._boundary) {
     this._generateBoundary();
diff --git a/test/integration/test-set-boundary.js b/test/integration/test-set-boundary.js
@@ -0,0 +1,37 @@
+'use strict';
+
+var common = require('../common');
+var assert = common.assert;
+
+var FormData = require(common.dir.lib + '/form_data');
+
+(function testSetBoundary() {
+  var userBoundary = '---something';
+  var form = new FormData();
+  form.setBoundary(userBoundary);
+
+  assert.equal(form.getBoundary(), userBoundary);
+}());
+
+(function testUniqueBoundaryPerFormAfterSet() {
+  var userBoundary = '---something';
+  var formA = new FormData();
+  formA.setBoundary(userBoundary);
+
+  var formB = new FormData();
+
+  assert.equal(formA.getBoundary(), userBoundary);
+  assert.notEqual(formA.getBoundary(), formB.getBoundary());
+}());
+
+(function testSetBoundaryWithNonString() {
+  var form = new FormData();
+
+  var invalidValues = [123, null, undefined, { value: 123 }, ['---something']];
+
+  invalidValues.forEach(function (value) {
+    assert.throws(function () {
+      form.setBoundary(value);
+    }, TypeError);
+  });
+}());
