Moved bid validation into some adapter middleware. (prebid#772)

* Moved bidd validation into some adapter middleware.

* Ran gofmt -s to fix the build.

exchange/adapter_map.go

@@ -75,6 +75,8 @@ func newAdapterMap(client *http.Client, cfg *config.Configuration, infos adapter
 
 	allBidders := make(map[openrtb_ext.BidderName]adaptedBidder, len(ortbBidders)+len(legacyBidders))
 
+	// Wrap legacy and openrtb Bidders behind a common interface, so that the Exchange doesn't need to concern
+	// itself with the differences.
 	for name, bidder := range legacyBidders {
 		// Clean out any disabled bidders
 		if isEnabledBidder(cfg.Adapters, string(name)) {
@@ -87,6 +89,12 @@ func newAdapterMap(client *http.Client, cfg *config.Configuration, infos adapter
 			allBidders[name] = adaptBidder(adapters.EnforceBidderInfo(bidder, infos[string(name)]), client)
 		}
 	}
+
+	// Apply any middleware used for global Bidder logic.
+	for name, bidder := range allBidders {
+		allBidders[name] = ensureValidBids(bidder)
+	}
+
 	return allBidders
 }
 

exchange/bidder_validate_bids.go

@@ -0,0 +1,119 @@
+package exchange
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/mxmCherry/openrtb"
+	"github.com/prebid/prebid-server/openrtb_ext"
+	"golang.org/x/text/currency"
+)
+
+// ensureValidBids returns a bidder that removes invalid bids from the argument bidder's response.
+// These will be converted into errors instead.
+//
+// The goal here is to make sure that the response contains Bids which are valid given the initial Request,
+// so that Publishers can trust the Bids they get from Prebid Server.
+func ensureValidBids(bidder adaptedBidder) adaptedBidder {
+	return &validatedBidder{
+		bidder: bidder,
+	}
+}
+
+type validatedBidder struct {
+	bidder adaptedBidder
+}
+
+func (v *validatedBidder) requestBid(ctx context.Context, request *openrtb.BidRequest, name openrtb_ext.BidderName, bidAdjustment float64) (*pbsOrtbSeatBid, []error) {
+	seatBid, errs := v.bidder.requestBid(ctx, request, name, bidAdjustment)
+	if validationErrors := removeInvalidBids(request, seatBid); len(validationErrors) > 0 {
+		errs = append(errs, validationErrors...)
+	}
+	return seatBid, errs
+}
+
+// validateBids will run some validation checks on the returned bids and excise any invalid bids
+func removeInvalidBids(request *openrtb.BidRequest, seatBid *pbsOrtbSeatBid) []error {
+	// Exit early if there is nothing to do.
+	if seatBid == nil || len(seatBid.bids) == 0 {
+		return nil
+	}
+
+	// By design, default currency is USD.
+	if cerr := validateCurrency(request.Cur, seatBid.currency); cerr != nil {
+		seatBid.bids = nil
+		return []error{cerr}
+	}
+
+	errs := make([]error, 0, len(seatBid.bids))
+	validBids := make([]*pbsOrtbBid, 0, len(seatBid.bids))
+	for _, bid := range seatBid.bids {
+		if ok, berr := validateBid(bid); ok {
+			validBids = append(validBids, bid)
+		} else {
+			errs = append(errs, berr)
+		}
+	}
+	seatBid.bids = validBids
+	return errs
+}
+
+// validateCurrency will run currency validation checks and return true if it passes, false otherwise.
+func validateCurrency(requestAllowedCurrencies []string, bidCurrency string) error {
+	// Default currency is `USD` by design.
+	defaultCurrency := "USD"
+	// Make sure bid currency is a valid ISO currency code
+	if bidCurrency == "" {
+		// If bid currency is not set, then consider it's default currency.
+		bidCurrency = defaultCurrency
+	}
+	currencyUnit, cerr := currency.ParseISO(bidCurrency)
+	if cerr != nil {
+		return cerr
+	}
+	// Make sure the bid currency is allowed from bid request via `cur` field.
+	// If `cur` field array from bid request is empty, then consider it accepts the default currency.
+	currencyAllowed := false
+	if len(requestAllowedCurrencies) == 0 {
+		requestAllowedCurrencies = []string{defaultCurrency}
+	}
+	for _, allowedCurrency := range requestAllowedCurrencies {
+		if strings.ToUpper(allowedCurrency) == currencyUnit.String() {
+			currencyAllowed = true
+			break
+		}
+	}
+	if currencyAllowed == false {
+		return fmt.Errorf(
+			"Bid currency is not allowed. Was '%s', wants: ['%s']",
+			currencyUnit.String(),
+			strings.Join(requestAllowedCurrencies, "', '"),
+		)
+	}
+
+	return nil
+}
+
+// validateBid will run the supplied bid through validation checks and return true if it passes, false otherwise.
+func validateBid(bid *pbsOrtbBid) (bool, error) {
+	if bid.bid == nil {
+		return false, errors.New("Empty bid object submitted.")
+	}
+
+	if bid.bid.ID == "" {
+		return false, errors.New("Bid missing required field 'id'")
+	}
+	if bid.bid.ImpID == "" {
+		return false, fmt.Errorf("Bid \"%s\" missing required field 'impid'", bid.bid.ID)
+	}
+	if bid.bid.Price <= 0.0 {
+		return false, fmt.Errorf("Bid \"%s\" does not contain a positive 'price'", bid.bid.ID)
+	}
+	if bid.bid.CrID == "" {
+		return false, fmt.Errorf("Bid \"%s\" missing creative ID", bid.bid.ID)
+	}
+
+	return true, nil
+}