Fix reverse domain resolving

intel/entity.go

@@ -43,6 +43,10 @@ type Entity struct {
 	// Domain is the target domain of the connection.
 	Domain string
 
+	// ReverseDomain is the domain the IP address points to. This is only
+	// resolved and populated when needed.
+	ReverseDomain string
+
 	// CNAME is a list of domain names that have been
 	// resolved for Domain.
 	CNAME []string
@@ -150,11 +154,6 @@ func (e *Entity) EnableReverseResolving() {
 
 func (e *Entity) reverseResolve(ctx context.Context) {
 	e.reverseResolveOnce.Do(func() {
-		// check if we should resolve
-		if !e.reverseResolveEnabled {
-			return
-		}
-
 		// need IP!
 		if e.IP == nil {
 			return
@@ -170,13 +169,20 @@ func (e *Entity) reverseResolve(ctx context.Context) {
 			log.Tracer(ctx).Warningf("intel: failed to resolve IP %s: %s", e.IP, err)
 			return
 		}
-		e.Domain = domain
+		e.ReverseDomain = domain
 	})
 }
 
 // GetDomain returns the domain and whether it is set.
-func (e *Entity) GetDomain() (string, bool) {
-	e.reverseResolve()
+func (e *Entity) GetDomain(ctx context.Context, mayUseReverseDomain bool) (string, bool) {
+	if mayUseReverseDomain && e.reverseResolveEnabled {
+		e.reverseResolve(ctx)
+
+		if e.ReverseDomain == "" {
+			return "", false
+		}
+		return e.ReverseDomain, true
+	}
 
 	if e.Domain == "" {
 		return "", false
@@ -268,7 +274,7 @@ func (e *Entity) getDomainLists(ctx context.Context) {
 		return
 	}
 
-	domain, ok := e.GetDomain()
+	domain, ok := e.GetDomain(ctx, false /* mayUseReverseDomain */)
 	if !ok {
 		return
 	}