POC levers for deterministic KDC precedence

Kerberos.NET/Client/Transport/ClientDomainService.cs

@@ -71,7 +71,10 @@ public virtual async Task<IEnumerable<DnsRecord>> LocateKdc(string domain, strin
             var results = await this.Query(domain, servicePrefix, DefaultKerberosPort);
 
             results = ParseQuerySrvReply(results);
-
+            if (this.Configuration.Defaults.PrioritizeKdcByConfigurationOrder)
+            {
+                return results;
+            }
             return await WeightResults(results);
         }
 
@@ -266,15 +269,16 @@ private async Task QueryDns(string domain, string servicePrefix, List<DnsRecord>
             }
         }
 
-        private static DnsRecord ParseKdcEntryAsSrvRecord(string kdc, string realm, string servicePrefix, int defaultPort)
+        private DnsRecord ParseKdcEntryAsSrvRecord(string kdc, string realm, string servicePrefix, int defaultPort)
         {
             if (IsUri(kdc))
             {
                 return new DnsRecord
                 {
                     Target = kdc,
                     Type = DnsRecordType.SRV,
-                    Name = realm
+                    Name = realm,
+                    TimeToLive = this.Configuration.Defaults.ConfiguredKdcTimeToLive
                 };
             }
 
@@ -284,7 +288,8 @@ private static DnsRecord ParseKdcEntryAsSrvRecord(string kdc, string realm, stri
             {
                 Target = split[0],
                 Type = DnsRecordType.SRV,
-                Name = $"{servicePrefix}.{realm}"
+                Name = $"{servicePrefix}.{realm}",
+                TimeToLive = this.Configuration.Defaults.ConfiguredKdcTimeToLive
             };
 
             if (split.Length > 1)

Kerberos.NET/Configuration/Krb5ConfigDefaults.cs

@@ -353,5 +353,19 @@ public class Krb5ConfigDefaults : Krb5ConfigObject
         [DefaultValue(true)]
         [DisplayName("prioritize_by_response_time")]
         public bool PrioritizeKdcByPing { get; set; }
+
+        /// <summary>
+        /// Indicates whether the client should try to utilze the order of KDCs as they are listed in the configuration when attempting to contact them, rather than trying to ping them first.
+        /// </summary>
+        [DefaultValue(false)]
+        [DisplayName("prioritize_by_configuration_order")]
+        public bool PrioritizeKdcByConfigurationOrder { get; set; }
+
+        /// <summary>
+        /// When attempting various KDCs this is how long a given KDC can be listed in the negative cache in seconds.
+        /// </summary>
+        [DefaultValue(0)]
+        [DisplayName("configured_kdc_time_to_live")]
+        public int ConfiguredKdcTimeToLive { get; set; }
     }
 }