From 27a696d650e1e3fb99e6f60e143723494345a6a5 Mon Sep 17 00:00:00 2001
From: linux019 <anode.dev@gmail.com>
Date: Tue, 9 Dec 2025 04:57:26 +0200
Subject: [PATCH] Warn in auction response for bidders blocked by privacy
 settings (#4537)

Co-authored-by: oleksandr <oleksandr@assertive.ai>
---
 errortypes/code.go     |  1 +
 exchange/utils.go      |  4 ++++
 exchange/utils_test.go | 16 +++++++++++++---
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/errortypes/code.go b/errortypes/code.go
index 2e20f8ff9..07b472772 100644
--- a/errortypes/code.go
+++ b/errortypes/code.go
@@ -40,6 +40,7 @@ const (
 	InvalidUserUIDsWarningCode
 	TooLongTargetingPrefixWarningCode
 	TooShortTargetingPrefixWarningCode
+	BidderBlockedByPrivacySettings
 )
 
 // Coder provides an error or warning code with severity.
diff --git a/exchange/utils.go b/exchange/utils.go
index 08ea0186d..37521b3ec 100644
--- a/exchange/utils.go
+++ b/exchange/utils.go
@@ -195,6 +195,10 @@ func (rs *requestSplitter) cleanOpenRTBRequests(ctx context.Context,
 
 		// privacy blocking
 		if rs.isBidderBlockedByPrivacy(reqWrapperCopy, auctionReq.Activities, auctionPermissions, coreBidder, openrtb_ext.BidderName(bidder)) {
+			errs = append(errs, &errortypes.Warning{
+				Message:     fmt.Sprintf("bidder %q blocked by privacy settings", coreBidder),
+				WarningCode: errortypes.BidderBlockedByPrivacySettings,
+			})
 			continue
 		}
 
diff --git a/exchange/utils_test.go b/exchange/utils_test.go
index 1b08ee1a3..cde4566c0 100644
--- a/exchange/utils_test.go
+++ b/exchange/utils_test.go
@@ -2454,6 +2454,7 @@ func TestCleanOpenRTBRequestsGDPRBlockBidRequest(t *testing.T) {
 		gdprAllowedBidders     []openrtb_ext.BidderName
 		expectedBidders        []openrtb_ext.BidderName
 		expectedBlockedBidders []openrtb_ext.BidderName
+		expectedErrors         []error
 	}{
 		{
 			description:            "gdpr enforced, one request allowed and one request blocked",
@@ -2461,6 +2462,10 @@ func TestCleanOpenRTBRequestsGDPRBlockBidRequest(t *testing.T) {
 			gdprAllowedBidders:     []openrtb_ext.BidderName{openrtb_ext.BidderAppnexus},
 			expectedBidders:        []openrtb_ext.BidderName{openrtb_ext.BidderAppnexus},
 			expectedBlockedBidders: []openrtb_ext.BidderName{openrtb_ext.BidderRubicon},
+			expectedErrors: []error{&errortypes.Warning{
+				Message:     `bidder "rubicon" blocked by privacy settings`,
+				WarningCode: errortypes.BidderBlockedByPrivacySettings,
+			}},
 		},
 		{
 			description:            "gdpr enforced, two requests allowed and no requests blocked",
@@ -2528,7 +2533,7 @@ func TestCleanOpenRTBRequestsGDPRBlockBidRequest(t *testing.T) {
 			bidders = append(bidders, req.BidderName)
 		}
 
-		assert.Empty(t, errs, test.description)
+		assert.Equal(t, test.expectedErrors, errs, test.description)
 		assert.ElementsMatch(t, bidders, test.expectedBidders, test.description)
 
 		for _, blockedBidder := range test.expectedBlockedBidders {
@@ -5121,6 +5126,7 @@ func TestCleanOpenRTBRequestsActivities(t *testing.T) {
 		expectedDevice    openrtb2.Device
 		expectedSource    openrtb2.Source
 		expectedImpExt    json.RawMessage
+		expectedErrors    []error
 	}{
 		{
 			name:              "fetch_bids_request_with_one_bidder_allowed",
@@ -5140,6 +5146,10 @@ func TestCleanOpenRTBRequestsActivities(t *testing.T) {
 			expectedUser:      expectedUserDefault,
 			expectedDevice:    expectedDeviceDefault,
 			expectedSource:    expectedSourceDefault,
+			expectedErrors: []error{&errortypes.Warning{
+				Message:     `bidder "appnexus" blocked by privacy settings`,
+				WarningCode: errortypes.BidderBlockedByPrivacySettings,
+			}},
 		},
 		{
 			name:              "transmit_ufpd_allowed",
@@ -5283,8 +5293,8 @@ func TestCleanOpenRTBRequestsActivities(t *testing.T) {
 				bidderInfo:        config.BidderInfos{"appnexus": config.BidderInfo{OpenRTB: &config.OpenRTBInfo{Version: test.ortbVersion}}},
 			}
 
-			bidderRequests, _, errs := reqSplitter.cleanOpenRTBRequests(context.Background(), auctionReq, nil, gdpr.SignalNo, false, map[string]float64{})
-			assert.Empty(t, errs)
+			bidderRequests, _, errs := reqSplitter.cleanOpenRTBRequests(context.Background(), auctionReq, nil, map[string]float64{})
+			assert.Equal(t, test.expectedErrors, errs)
 			assert.Len(t, bidderRequests, test.expectedReqNumber)
 
 			if test.expectedReqNumber == 1 {