Enabled discrimination on target namespace

Generalized ResourcePolicyRule in API Priority and Fairness to be able
to discriminate on the target namespace (if any) specified in the
request.

pkg/apis/flowcontrol/validation/validation.go

@@ -245,9 +245,31 @@ func ValidateFlowSchemaResourcePolicyRule(rule *flowcontrol.ResourcePolicyRule,
 		allErrs = append(allErrs, field.Invalid(fldPath.Child("resources"), rule.Resources, "if '*' is present, must not specify other resources"))
 	}
 
+	if len(rule.Namespaces) == 0 {
+		allErrs = append(allErrs, field.Required(fldPath.Child("namespaces"), "resource rules must supply at least one namespace"))
+	} else if memberInList(flowcontrol.NamespaceEvery, rule.Namespaces...) {
+		for _, tgtNS := range rule.Namespaces {
+			if tgtNS != flowcontrol.NamespaceEvery && tgtNS != flowcontrol.NamespaceClusterScope {
+				allErrs = append(allErrs, field.Invalid(fldPath.Child("namespaces"), rule.Namespaces, "'*' may be accompanied only by 'Cluster Scope'"))
+				break
+			}
+		}
+	} else {
+		for idx, tgtNS := range rule.Namespaces {
+			if tgtNS == flowcontrol.NamespaceClusterScope {
+				continue
+			}
+			for _, msg := range apimachineryvalidation.ValidateNamespaceName(tgtNS, false) {
+				allErrs = append(allErrs, field.Invalid(fldPath.Child("namespaces").Index(idx), tgtNS, nsErrIntro+msg))
+			}
+		}
+	}
+
 	return allErrs
 }
 
+const nsErrIntro = "each member of this list must be '*', 'Cluster Scope', or a DNS-1123 label; "
+
 // ValidateFlowSchemaStatus validates status for the flow-schema.
 func ValidateFlowSchemaStatus(status *flowcontrol.FlowSchemaStatus, fldPath *field.Path) field.ErrorList {
 	var allErrs field.ErrorList
@@ -424,8 +446,12 @@ func ValidateNonResourceURLPath(path string, fldPath *field.Path) *field.Error {
 }
 
 func hasWildcard(operations []string) bool {
-	for _, o := range operations {
-		if o == "*" {
+	return memberInList("*", operations...)
+}
+
+func memberInList(seek string, a ...string) bool {
+	for _, ai := range a {
+		if ai == seek {
 			return true
 		}
 	}