Set cookie domain in pubcid / userid on main domain, not subdomain

modules/pubCommonIdSystem.js

@@ -7,11 +7,14 @@
 
 import * as utils from '../src/utils.js';
 import {submodule} from '../src/hook.js';
+import {getCoreStorageManager} from '../src/storageManager.js';
 
 const PUB_COMMON_ID = 'PublisherCommonId';
 
 const MODULE_NAME = 'pubCommonId';
 
+const coreStorage = getCoreStorageManager('userid');
+
 /** @type {Submodule} */
 export const pubCommonIdSubmodule = {
   /**
@@ -90,6 +93,33 @@ export const pubCommonIdSubmodule = {
       const callback = this.makeCallback(pixelUrl, storedId);
       return callback ? {callback: callback} : {id: storedId};
     }
+  },
+
+  /**
+   * @param {string} domain
+   * @param {HTMLDocument} document
+   * @return {(string|undefined)}
+   */
+  domainOverride: function () {
+    const domainElements = document.domain.split('.');
+    const cookieName = `_gd${Date.now()}`;
+    for (let i = 0, topDomain; i < domainElements.length; i++) {
+      const nextDomain = domainElements.slice(i).join('.');
+
+      // write test cookie
+      coreStorage.setCookie(cookieName, '1', undefined, undefined, nextDomain);
+
+      // read test cookie to verify domain was valid
+      if (coreStorage.getCookie(cookieName) === '1') {
+        // delete test cookie
+        coreStorage.setCookie(cookieName, '', 'Thu, 01 Jan 1970 00:00:01 GMT', undefined, nextDomain);
+        // cookie was written successfully using test domain so the topDomain is updated
+        topDomain = nextDomain;
+      } else {
+        // cookie failed to write using test domain so exit by returning the topDomain
+        return topDomain;
+      }
+    }
   }
 };
 

modules/userId/index.js

@@ -159,17 +159,23 @@ export function setSubmoduleRegistry(submodules) {
 }
 
 /**
- * @param {SubmoduleStorage} storage
+ * @param {SubmoduleContainer} submodule
  * @param {(Object|string)} value
  */
-function setStoredValue(storage, value) {
+function setStoredValue(submodule, value) {
+  /**
+   * @type {SubmoduleStorage}
+   */
+  const storage = submodule.config.storage;
+  const domainOverride = (typeof submodule.submodule.domainOverride === 'function') ? submodule.submodule.domainOverride() : null;
+
   try {
     const valueStr = utils.isPlainObject(value) ? JSON.stringify(value) : value;
     const expiresStr = (new Date(Date.now() + (storage.expires * (60 * 60 * 24 * 1000)))).toUTCString();
     if (storage.type === COOKIE) {
-      coreStorage.setCookie(storage.name, valueStr, expiresStr, 'Lax');
+      coreStorage.setCookie(storage.name, valueStr, expiresStr, 'Lax', domainOverride);
       if (typeof storage.refreshInSeconds === 'number') {
-        coreStorage.setCookie(`${storage.name}_last`, new Date().toUTCString(), expiresStr);
+        coreStorage.setCookie(`${storage.name}_last`, new Date().toUTCString(), expiresStr, 'Lax', domainOverride);
       }
     } else if (storage.type === LOCAL_STORAGE) {
       coreStorage.setDataInLocalStorage(`${storage.name}_exp`, expiresStr);
@@ -246,7 +252,7 @@ function processSubmoduleCallbacks(submodules, cb) {
       // if valid, id data should be saved to cookie/html storage
       if (idObj) {
         if (submodule.config.storage) {
-          setStoredValue(submodule.config.storage, idObj);
+          setStoredValue(submodule, idObj);
         }
         // cache decoded value (this is copied to every adUnit bid)
         submodule.idObj = submodule.submodule.decode(idObj);
@@ -437,7 +443,7 @@ function initSubmodules(submodules, consentData) {
       if (utils.isPlainObject(response)) {
         if (response.id) {
           // A getId/extendId result assumed to be valid user id data, which should be saved to users local storage or cookies
-          setStoredValue(submodule.config.storage, response.id);
+          setStoredValue(submodule, response.id);
           storedId = response.id;
         }