WURFL RTD: Remove fingerprinting APIs from LCE detection (prebid#14251)

* WURFL RTD: send beacon on no bids

* WURFL RTD: allow to not apply abtest to LCE bids (#4)

* WURFL RTD: remove fingerprinting APIs from LCE detection

Remove screen.availWidth usage from LCE device detection to comply with
fingerprinting API restrictions.

* WURFL RTD: remove setting of `device.w` and `device.h` in LCE enrichment

LCE enrichment no longer sets `device.w` and `device.h` as these fields
are already populated by Prebid.

Author: lucor

modules/wurflRtdProvider.js

@@ -13,7 +13,7 @@ import { getGlobal } from '../src/prebidGlobal.js';
 // Constants
 const REAL_TIME_MODULE = 'realTimeData';
 const MODULE_NAME = 'wurfl';
-const MODULE_VERSION = '2.1.0';
+const MODULE_VERSION = '2.3.0';
 
 // WURFL_JS_HOST is the host for the WURFL service endpoints
 const WURFL_JS_HOST = 'https://prebid.wurflcloud.com';
@@ -53,8 +53,7 @@ const ENRICHMENT_TYPE = {
   LCE: 'lce',
   LCE_ERROR: 'lcefailed',
   WURFL_PUB: 'wurfl_pub',
-  WURFL_SSP: 'wurfl_ssp',
-  WURFL_PUB_SSP: 'wurfl_pub_ssp'
+  WURFL_SSP: 'wurfl_ssp'
 };
 
 // Consent class constants
@@ -76,7 +75,9 @@ const AB_TEST = {
   CONTROL_GROUP: 'control',
   TREATMENT_GROUP: 'treatment',
   DEFAULT_SPLIT: 0.5,
-  DEFAULT_NAME: 'unknown'
+  DEFAULT_NAME: 'unknown',
+  ENRICHMENT_TYPE_LCE: 'lce',
+  ENRICHMENT_TYPE_WURFL: 'wurfl'
 };
 
 const logger = prefixLog('[WURFL RTD Submodule]');
@@ -105,9 +106,6 @@ let tier;
 // overQuota stores the over_quota flag from wurfl_pbjs data (possible values: 0, 1)
 let overQuota;
 
-// abTest stores A/B test configuration and variant (set by init)
-let abTest;
-
 /**
  * Safely gets an object from localStorage with JSON parsing
  * @param {string} key The storage key
@@ -322,21 +320,6 @@ function shouldSample(rate) {
   return randomValue < rate;
 }
 
-/**
- * getABVariant determines A/B test variant assignment based on split
- * @param {number} split Treatment group split from 0-1 (float, e.g., 0.5 = 50% treatment)
- * @returns {string} AB_TEST.TREATMENT_GROUP or AB_TEST.CONTROL_GROUP
- */
-function getABVariant(split) {
-  if (split >= 1) {
-    return AB_TEST.TREATMENT_GROUP;
-  }
-  if (split <= 0) {
-    return AB_TEST.CONTROL_GROUP;
-  }
-  return Math.random() < split ? AB_TEST.TREATMENT_GROUP : AB_TEST.CONTROL_GROUP;
-}
-
 /**
  * getConsentClass calculates the consent classification level
  * @param {Object} userConsent User consent data
@@ -942,26 +925,9 @@ const WurflLCEDevice = {
       return window.screen.deviceXDPI / window.screen.logicalXDPI;
     }
 
-    const screenWidth = window.screen.availWidth;
-    const docWidth = window.document?.documentElement?.clientWidth;
-
-    if (screenWidth && docWidth && docWidth > 0) {
-      return Math.round(screenWidth / docWidth);
-    }
-
     return undefined;
   },
 
-  _getScreenWidth(pixelRatio) {
-    // Assumes window.screen exists (caller checked)
-    return Math.round(window.screen.width * pixelRatio);
-  },
-
-  _getScreenHeight(pixelRatio) {
-    // Assumes window.screen exists (caller checked)
-    return Math.round(window.screen.height * pixelRatio);
-  },
-
   _getMake(ua) {
     for (const [makeToken, brandName] of this._makeMapping) {
       if (ua.includes(makeToken)) {
@@ -1039,16 +1005,6 @@ const WurflLCEDevice = {
       const pixelRatio = this._getDevicePixelRatioValue();
       if (pixelRatio !== undefined) {
         device.pxratio = pixelRatio;
-
-        const width = this._getScreenWidth(pixelRatio);
-        if (width !== undefined) {
-          device.w = width;
-        }
-
-        const height = this._getScreenHeight(pixelRatio);
-        if (height !== undefined) {
-          device.h = height;
-        }
       }
     }
 
@@ -1066,6 +1022,105 @@ const WurflLCEDevice = {
 };
 // ==================== END WURFL LCE DEVICE MODULE ====================
 
+// ==================== A/B TEST MANAGER  ====================
+
+const ABTestManager = {
+  _enabled: false,
+  _name: null,
+  _variant: null,
+  _excludeLCE: true,
+  _enrichmentType: null,
+
+  /**
+   * Initializes A/B test configuration
+   * @param {Object} params Configuration params from config.params
+   */
+  init(params) {
+    this._enabled = false;
+    this._name = null;
+    this._variant = null;
+    this._excludeLCE = true;
+    this._enrichmentType = null;
+
+    const abTestEnabled = params?.abTest ?? false;
+    if (!abTestEnabled) {
+      return;
+    }
+
+    this._enabled = true;
+    this._name = params?.abName ?? AB_TEST.DEFAULT_NAME;
+    this._excludeLCE = params?.abExcludeLCE ?? true;
+
+    const split = params?.abSplit ?? AB_TEST.DEFAULT_SPLIT;
+    this._variant = this._computeVariant(split);
+
+    logger.logMessage(`A/B test "${this._name}": user in ${this._variant} group (exclude_lce: ${this._excludeLCE})`);
+  },
+
+  /**
+   * _computeVariant determines A/B test variant assignment based on split
+   * @param {number} split Treatment group split from 0-1 (float, e.g., 0.5 = 50% treatment)
+   * @returns {string} AB_TEST.TREATMENT_GROUP or AB_TEST.CONTROL_GROUP
+   */
+  _computeVariant(split) {
+    if (split >= 1) {
+      return AB_TEST.TREATMENT_GROUP;
+    }
+    if (split <= 0) {
+      return AB_TEST.CONTROL_GROUP;
+    }
+    return Math.random() < split ? AB_TEST.TREATMENT_GROUP : AB_TEST.CONTROL_GROUP;
+  },
+
+  /**
+   * Sets the enrichment type encountered in current auction
+   * @param {string} enrichmentType 'lce' or 'wurfl'
+   */
+  setEnrichmentType(enrichmentType) {
+    this._enrichmentType = enrichmentType;
+  },
+
+  /**
+   * Checks if A/B test is enabled for current auction
+   * @returns {boolean} True if A/B test should be applied
+   */
+  isEnabled() {
+    if (!this._enabled) return false;
+    if (this._enrichmentType === AB_TEST.ENRICHMENT_TYPE_LCE && this._excludeLCE) {
+      return false;
+    }
+    return true;
+  },
+
+  /**
+   * Checks if enrichment should be skipped (control group)
+   * @returns {boolean} True if enrichment should be skipped
+   */
+  isInControlGroup() {
+    if (!this.isEnabled()) {
+      return false;
+    }
+    return (this._variant === AB_TEST.CONTROL_GROUP)
+  },
+
+  /**
+   * Gets beacon payload fields (returns null if not active for auction)
+   * @returns {Object|null}
+   */
+  getBeaconPayload() {
+    if (!this.isEnabled()) {
+      return null;
+    }
+
+    return {
+      ab_name: this._name,
+      ab_variant: this._variant
+    };
+  }
+};
+
+// ==================== END A/B TEST MANAGER MODULE ====================
+
 // ==================== EXPORTED FUNCTIONS ====================
 
 /**
@@ -1084,22 +1139,12 @@ const init = (config, userConsent) => {
   samplingRate = DEFAULT_SAMPLING_RATE;
   tier = '';
   overQuota = DEFAULT_OVER_QUOTA;
-  abTest = null;
-
-  // A/B testing: set if enabled
-  const abTestEnabled = config?.params?.abTest ?? false;
-  if (abTestEnabled) {
-    const abName = config?.params?.abName ?? AB_TEST.DEFAULT_NAME;
-    const abSplit = config?.params?.abSplit ?? AB_TEST.DEFAULT_SPLIT;
-    const abVariant = getABVariant(abSplit);
-    abTest = { ab_name: abName, ab_variant: abVariant };
-    logger.logMessage(`A/B test "${abName}": user in ${abVariant} group`);
-  }
 
-  logger.logMessage('initialized', {
-    version: MODULE_VERSION,
-    abTest: abTest ? `${abTest.ab_name}:${abTest.ab_variant}` : 'disabled'
-  });
+  logger.logMessage('initialized', { version: MODULE_VERSION });
+
+  // A/B testing: initialize ABTestManager
+  ABTestManager.init(config?.params);
+
   return true;
 }
 
@@ -1123,8 +1168,16 @@ const getBidRequestData = (reqBidsConfigObj, callback, config, userConsent) => {
     });
   });
 
-  // A/B test: Skip enrichment for control group but allow beacon sending
-  if (abTest && abTest.ab_variant === AB_TEST.CONTROL_GROUP) {
+  // Determine enrichment type based on cache availability
+  WurflDebugger.cacheReadStart();
+  const cachedWurflData = getObjectFromStorage(WURFL_RTD_STORAGE_KEY);
+  WurflDebugger.cacheReadStop();
+
+  const abEnrichmentType = cachedWurflData ? AB_TEST.ENRICHMENT_TYPE_WURFL : AB_TEST.ENRICHMENT_TYPE_LCE;
+  ABTestManager.setEnrichmentType(abEnrichmentType);
+
+  // A/B test: Skip enrichment for control group
+  if (ABTestManager.isInControlGroup()) {
     logger.logMessage('A/B test control group: skipping enrichment');
     enrichmentType = ENRICHMENT_TYPE.NONE;
     bidders.forEach(bidder => bidderEnrichment.set(bidder, ENRICHMENT_TYPE.NONE));
@@ -1134,10 +1187,6 @@ const getBidRequestData = (reqBidsConfigObj, callback, config, userConsent) => {
   }
 
   // Priority 1: Check if WURFL.js response is cached
-  WurflDebugger.cacheReadStart();
-  const cachedWurflData = getObjectFromStorage(WURFL_RTD_STORAGE_KEY);
-  WurflDebugger.cacheReadStop();
-
   if (cachedWurflData) {
     const isExpired = cachedWurflData.expire_at && Date.now() > cachedWurflData.expire_at;
 
@@ -1248,8 +1297,14 @@ function onAuctionEndEvent(auctionDetails, config, userConsent) {
     host = statsHost;
   }
 
-  const url = new URL(host);
-  url.pathname = STATS_ENDPOINT_PATH;
+  let url;
+  try {
+    url = new URL(host);
+    url.pathname = STATS_ENDPOINT_PATH;
+  } catch (e) {
+    logger.logError('Invalid stats host URL:', host);
+    return;
+  }
 
   // Calculate consent class
   let consentClass;
@@ -1261,12 +1316,6 @@ function onAuctionEndEvent(auctionDetails, config, userConsent) {
     consentClass = CONSENT_CLASS.ERROR;
   }
 
-  // Only send beacon if there are bids to report
-  if (!auctionDetails.bidsReceived || auctionDetails.bidsReceived.length === 0) {
-    logger.logMessage('auction completed - no bids received');
-    return;
-  }
-
   // Build a lookup object for winning bid request IDs
   const winningBids = getGlobal().getHighestCpmBids() || [];
   const winningBidIds = {};
@@ -1277,8 +1326,9 @@ function onAuctionEndEvent(auctionDetails, config, userConsent) {
 
   // Build a lookup object for bid responses: "adUnitCode:bidderCode" -> bid
   const bidResponseMap = {};
-  for (let i = 0; i < auctionDetails.bidsReceived.length; i++) {
-    const bid = auctionDetails.bidsReceived[i];
+  const bidsReceived = auctionDetails.bidsReceived || [];
+  for (let i = 0; i < bidsReceived.length; i++) {
+    const bid = bidsReceived[i];
     const adUnitCode = bid.adUnitCode;
     const bidderCode = bid.bidderCode || bid.bidder;
     const key = adUnitCode + ':' + bidderCode;
@@ -1295,8 +1345,9 @@ function onAuctionEndEvent(auctionDetails, config, userConsent) {
       const bidders = [];
 
       // Check each bidder configured for this ad unit
-      for (let j = 0; j < adUnit.bids.length; j++) {
-        const bidConfig = adUnit.bids[j];
+      const bids = adUnit.bids || [];
+      for (let j = 0; j < bids.length; j++) {
+        const bidConfig = bids[j];
         const bidderCode = bidConfig.bidder;
         const key = adUnitCode + ':' + bidderCode;
         const bidResponse = bidResponseMap[key];
@@ -1329,7 +1380,7 @@ function onAuctionEndEvent(auctionDetails, config, userConsent) {
   }
 
   logger.logMessage('auction completed', {
-    bidsReceived: auctionDetails.bidsReceived.length,
+    bidsReceived: auctionDetails.bidsReceived ? auctionDetails.bidsReceived.length : 0,
     bidsWon: winningBids.length,
     adUnits: adUnits.length
   });
@@ -1349,16 +1400,19 @@ function onAuctionEndEvent(auctionDetails, config, userConsent) {
   };
 
   // Add A/B test fields if enabled
-  if (abTest) {
-    payloadData.ab_name = abTest.ab_name;
-    payloadData.ab_variant = abTest.ab_variant;
+  const abPayload = ABTestManager.getBeaconPayload();
+  if (abPayload) {
+    payloadData.ab_name = abPayload.ab_name;
+    payloadData.ab_variant = abPayload.ab_variant;
   }
 
   const payload = JSON.stringify(payloadData);
 
+  // Both sendBeacon and fetch send as text/plain to avoid CORS preflight requests.
+  // Server must parse body as JSON regardless of Content-Type header.
   const sentBeacon = sendBeacon(url.toString(), payload);
   if (sentBeacon) {
-    WurflDebugger.setBeaconPayload(JSON.parse(payload));
+    WurflDebugger.setBeaconPayload(payloadData);
     return;
   }
 
@@ -1367,9 +1421,11 @@ function onAuctionEndEvent(auctionDetails, config, userConsent) {
     body: payload,
     mode: 'no-cors',
     keepalive: true
+  }).catch((e) => {
+    logger.logError('Failed to send beacon via fetch:', e);
   });
 
-  WurflDebugger.setBeaconPayload(JSON.parse(payload));
+  WurflDebugger.setBeaconPayload(payloadData);
 }
 
 // ==================== MODULE EXPORT ====================

modules/wurflRtdProvider.md

@@ -49,15 +49,16 @@ pbjs.setConfig({
 
 ### Parameters
 
-| Name           | Type    | Description                                                      | Default        |
-| :------------- | :------ | :--------------------------------------------------------------- | :------------- |
-| name           | String  | Real time data module name                                       | Always 'wurfl' |
-| waitForIt      | Boolean | Should be `true` if there's an `auctionDelay` defined (optional) | `false`        |
-| params         | Object  |                                                                  |                |
-| params.altHost | String  | Alternate host to connect to WURFL.js                            |                |
-| params.abTest  | Boolean | Enable A/B testing mode                                          | `false`        |
-| params.abName  | String  | A/B test name identifier                                         | `'unknown'`    |
-| params.abSplit | Number  | Fraction of users in treatment group (0-1)                       | `0.5`          |
+| Name                | Type    | Description                                                      | Default        |
+| :------------------ | :------ | :--------------------------------------------------------------- | :------------- |
+| name                | String  | Real time data module name                                       | Always 'wurfl' |
+| waitForIt           | Boolean | Should be `true` if there's an `auctionDelay` defined (optional) | `false`        |
+| params              | Object  |                                                                  |                |
+| params.altHost      | String  | Alternate host to connect to WURFL.js                            |                |
+| params.abTest       | Boolean | Enable A/B testing mode                                          | `false`        |
+| params.abName       | String  | A/B test name identifier                                         | `'unknown'`    |
+| params.abSplit      | Number  | Fraction of users in treatment group (0-1)                       | `0.5`          |
+| params.abExcludeLCE | Boolean | Don't apply A/B testing to LCE bids                              | `true`         |
 
 ### A/B Testing