Add "partitioned" option for CHIPS support

HISTORY.md

@@ -1,6 +1,7 @@
 unreleased
 ==========
 
+  * Add `partitioned` option for CHIPS support
   * Add `priority` option for Priority cookie support
   * Fix accidental cookie name/value truncation when given invalid chars
   * Fix `maxAge` option to reject invalid values

README.md

@@ -71,6 +71,7 @@ If the _options_ object is provided, it will be used to generate the outbound co
 * `domain`: a string indicating the domain of the cookie (no default).
 * `secure`: a boolean indicating whether the cookie is only to be sent over HTTPS (`false` by default for HTTP, `true` by default for HTTPS). [Read more about this option below](#secure-cookies).
 * `httpOnly`: a boolean indicating whether the cookie is only to be sent over HTTP(S), and not made available to client JavaScript (`true` by default).
+* `partitioned`: a boolean indicating whether to partition the cookie in Chrome for the [CHIPS Update](https://developers.google.com/privacy-sandbox/3pcd/chips) (`false` by default). If this is true, Cookies from embedded sites will be partitioned and only readable from the same top level site from which it was created.
 * `priority`: a string indicating the cookie priority. This can be set to `'low'`, `'medium'`, or `'high'`.
 * `sameSite`: a boolean or string indicating whether the cookie is a "same site" cookie (`false` by default). This can be set to `'strict'`, `'lax'`, `'none'`, or `true` (which maps to `'strict'`).
 * `signed`: a boolean indicating whether the cookie is to be signed (`false` by default). If this is true, another cookie of the same name with the `.sig` suffix appended will also be sent, with a 27-byte url-safe base64 SHA1 value representing the hash of _cookie-name_=_cookie-value_ against the first [Keygrip](https://www.npmjs.com/package/keygrip) key. This signature key is used to detect tampering the next time a cookie is received.

index.js

@@ -189,6 +189,7 @@ Cookie.prototype.path = "/";
 Cookie.prototype.expires = undefined;
 Cookie.prototype.domain = undefined;
 Cookie.prototype.httpOnly = true;
+Cookie.prototype.partitioned = false
 Cookie.prototype.priority = undefined
 Cookie.prototype.sameSite = false;
 Cookie.prototype.secure = false;
@@ -210,6 +211,7 @@ Cookie.prototype.toHeader = function() {
   if (this.sameSite ) header += "; samesite=" + (this.sameSite === true ? 'strict' : this.sameSite.toLowerCase())
   if (this.secure   ) header += "; secure"
   if (this.httpOnly ) header += "; httponly"
+  if (this.partitioned) header += '; partitioned'
 
   return header
 };

test/cookie.js

@@ -81,6 +81,32 @@ describe('new Cookie(name, value, [options])', function () {
       })
     })
 
+    describe('partitioned', function () {
+      it('should set the .partitioned property', function () {
+        var cookie = new cookies.Cookie('foo', 'bar', { partitioned: true })
+        assert.strictEqual(cookie.partitioned, true)
+      })
+
+      it('should default to false', function () {
+        var cookie = new cookies.Cookie('foo', 'bar')
+        assert.strictEqual(cookie.partitioned, false)
+      })
+
+      describe('when set to false', function () {
+        it('should not set partitioned attribute in header', function () {
+          var cookie = new cookies.Cookie('foo', 'bar', { partitioned: false })
+          assert.strictEqual(cookie.toHeader(), 'foo=bar; path=/; httponly')
+        })
+      })
+
+      describe('when set to true', function () {
+        it('should set partitioned attribute in header', function () {
+          var cookie = new cookies.Cookie('foo', 'bar', { partitioned: true })
+          assert.strictEqual(cookie.toHeader(), 'foo=bar; path=/; httponly; partitioned')
+        })
+      })
+    })
+
     describe('priority', function () {
       it('should set the .priority property', function () {
         var cookie = new cookies.Cookie('foo', 'bar', { priority: 'low' })

test/test.js

@@ -339,6 +339,32 @@ describe('new Cookies(req, res, [options])', function () {
       })
     })
 
+    describe('"partitioned" option', function () {
+      it('should not be set by default', function (done) {
+        request(createServer(setCookieHandler('foo', 'bar')))
+          .get('/')
+          .expect(200)
+          .expect(shouldSetCookieWithoutAttribute('foo', 'partitioned'))
+          .end(done)
+      })
+
+      it('should set to true', function (done) {
+        request(createServer(setCookieHandler('foo', 'bar', { partitioned: true })))
+          .get('/')
+          .expect(200)
+          .expect(shouldSetCookieWithAttribute('foo', 'partitioned'))
+          .end(done)
+      })
+
+      it('should set to false', function (done) {
+        request(createServer(setCookieHandler('foo', 'bar', { partitioned: false })))
+          .get('/')
+          .expect(200)
+          .expect(shouldSetCookieWithoutAttribute('foo', 'partitioned'))
+          .end(done)
+      })
+    })
+
     describe('"path" option', function () {
       it('should default to "/"', function (done) {
         request(createServer(setCookieHandler('foo', 'bar')))