Add ASN field to DMARC events

dmarc.go

@@ -153,6 +153,9 @@ func (h *DMARCHandler) eventFromRecord(report *dmarcReport, rec *dmarcRecord) Ev
 	e.Set("report_id", report.Metadata.ReportID)
 	e.Set("report_organization", report.Metadata.Organization)
 
+	if asn, ok := lookupASN(rec.Row.SourceIP); ok {
+		e.Set("asn", asn)
+	}
 	e.Set("policy_evaluated_disposition", rec.Row.PolicyEvaluated.Disposition)
 	e.Set("policy_evaluated_dkim", rec.Row.PolicyEvaluated.DKIM)
 	e.Set("policy_evaluated_spf", rec.Row.PolicyEvaluated.SPF)

ip.go

@@ -34,7 +34,11 @@ func lookupASN(addr string) (string, bool) {
 	geodbInit.Do(initGeoIP)
 
 	if geodb != nil {
-		asn, err := geodb.ASN(net.ParseIP(addr))
+		ip := net.ParseIP(addr)
+		if ip == nil {
+			return "", false
+		}
+		asn, err := geodb.ASN(ip)
 		if err == nil {
 			return fmt.Sprintf("AS%d", asn.AutonomousSystemNumber), true
 		}