Fix leaking host cookie to all bidders (prebid#1008)

endpoints/openrtb2/auction.go

@@ -894,7 +894,6 @@ func (deps *endpointDeps) setFieldsImplicitly(httpReq *http.Request, bidReq *ope
 	}
 	setImpsImplicitly(httpReq, bidReq.Imp)
 
-	deps.setUserImplicitly(httpReq, bidReq)
 	setAuctionTypeImplicitly(bidReq)
 }
 
@@ -1098,20 +1097,6 @@ func getStoredRequestId(data []byte) (string, bool, error) {
 	return string(value), true, nil
 }
 
-// setUserImplicitly uses implicit info from httpReq to populate bidReq.User
-func (deps *endpointDeps) setUserImplicitly(httpReq *http.Request, bidReq *openrtb.BidRequest) {
-	if bidReq.User == nil || bidReq.User.ID == "" {
-		if id, ok := parseUserID(deps.cfg, httpReq); ok {
-			if bidReq.User == nil {
-				bidReq.User = &openrtb.User{}
-			}
-			if bidReq.User.ID == "" {
-				bidReq.User.ID = id
-			}
-		}
-	}
-}
-
 // setIPImplicitly sets the IP address on bidReq, if it's not explicitly defined and we can figure it out.
 func setIPImplicitly(httpReq *http.Request, bidReq *openrtb.BidRequest) {
 	if bidReq.Device == nil || bidReq.Device.IP == "" {
@@ -1136,15 +1121,6 @@ func setUAImplicitly(httpReq *http.Request, bidReq *openrtb.BidRequest) {
 	}
 }
 
-// parseUserId gets this user's ID  for the host machine, if it exists.
-func parseUserID(cfg *config.Configuration, httpReq *http.Request) (string, bool) {
-	if hostCookie, err := httpReq.Cookie(cfg.HostCookie.CookieName); hostCookie != nil && err == nil {
-		return hostCookie.Value, true
-	} else {
-		return "", false
-	}
-}
-
 // Check if a request comes from a Safari browser
 func checkSafari(r *http.Request) (isSafari bool) {
 	isSafari = false

endpoints/openrtb2/auction_test.go

@@ -112,43 +112,6 @@ func TestExplicitUserId(t *testing.T) {
 	}
 }
 
-// TestImplicitUserId makes sure that that bidrequest.user.id gets populated from the host cookie, if it wasn't sent explicitly.
-func TestImplicitUserId(t *testing.T) {
-	cookieName := "userid"
-	mockId := "12345"
-	cfg := &config.Configuration{
-		MaxRequestSize: maxSize,
-		HostCookie: config.HostCookie{
-			CookieName: cookieName,
-		},
-	}
-	ex := &mockExchange{}
-
-	request := httptest.NewRequest("POST", "/openrtb2/auction", strings.NewReader(validRequest(t, "site.json")))
-	request.AddCookie(&http.Cookie{
-		Name:  cookieName,
-		Value: mockId,
-	})
-	// NewMetrics() will create a new go_metrics MetricsEngine, bypassing the need for a crafted configuration set to support it.
-	// As a side effect this gives us some coverage of the go_metrics piece of the metrics engine.
-	theMetrics := pbsmetrics.NewMetrics(metrics.NewRegistry(), openrtb_ext.BidderList())
-
-	endpoint, _ := NewEndpoint(ex, newParamsValidator(t), empty_fetcher.EmptyFetcher{}, empty_fetcher.EmptyFetcher{}, cfg, theMetrics, analyticsConf.NewPBSAnalytics(&config.Analytics{}), map[string]string{}, []byte{}, openrtb_ext.BidderMap)
-	endpoint(httptest.NewRecorder(), request, nil)
-
-	if ex.lastRequest == nil {
-		t.Fatalf("The request never made it into the Exchange.")
-	}
-
-	if ex.lastRequest.User == nil {
-		t.Fatalf("The exchange should have received a request with a non-nil user.")
-	}
-
-	if ex.lastRequest.User.ID != mockId {
-		t.Errorf("Bad User ID. Expected %s, got %s", mockId, ex.lastRequest.User.ID)
-	}
-}
-
 // TestGoodRequests makes sure we return 200s on good requests.
 func TestGoodRequests(t *testing.T) {
 	exemplary := &getResponseFromDirectory{