syntax = "proto3";

package envoy.data.dns.v4alpha;

import "envoy/type/matcher/v4alpha/string.proto";

import "google/protobuf/duration.proto";

import "udpa/annotations/status.proto";
import "udpa/annotations/versioning.proto";
import "validate/validate.proto";

option java_package = "io.envoyproxy.envoy.data.dns.v4alpha";
option java_outer_classname = "DnsTableProto";
option java_multiple_files = true;
option (udpa.annotations.file_status).package_version_status = NEXT_MAJOR_VERSION_CANDIDATE;

// [#protodoc-title: DNS Filter Table Data]
// :ref:`DNS Filter config overview <config_udp_listener_filters_dns_filter>`.

// This message contains the configuration for the DNS Filter if populated
// from the control plane
message DnsTable {
  option (udpa.annotations.versioning).previous_message_type = "envoy.data.dns.v3.DnsTable";

  // This message contains a list of IP addresses returned for a query for a known name
  message AddressList {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.data.dns.v3.DnsTable.AddressList";

    // This field contains a well formed IP address that is returned in the answer for a
    // name query. The address field can be an IPv4 or IPv6 address. Address family
    // detection is done automatically when Envoy parses the string. Since this field is
    // repeated, Envoy will return as many entries from this list in the DNS response while
    // keeping the response under 512 bytes
    repeated string address = 1 [(validate.rules).repeated = {
      min_items: 1
      items {string {min_len: 3}}
    }];
  }

  // This message type is extensible and can contain a list of addresses, clusters or
  // dictate a different method for resolving the addresses for an endpoint
  message DnsEndpoint {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.data.dns.v3.DnsTable.DnsEndpoint";

    oneof endpoint_config {
      option (validate.required) = true;

      AddressList address_list = 1;

      string cluster_name = 2;
    }
  }

  message DnsVirtualDomain {
    option (udpa.annotations.versioning).previous_message_type =
        "envoy.data.dns.v3.DnsTable.DnsVirtualDomain";

    // A domain name for which Envoy will respond to query requests
    string name = 1 [(validate.rules).string = {min_len: 1 well_known_regex: HTTP_HEADER_NAME}];

    // The configuration containing the method to determine the address of this endpoint
    DnsEndpoint endpoint = 2;

    // Sets the TTL in DNS answers from Envoy returned to the client. The default TTL is 300s
    google.protobuf.Duration answer_ttl = 3 [(validate.rules).duration = {gte {seconds: 30}}];
  }

  // Control how many times Envoy makes an attempt to forward a query to an external DNS server
  uint32 external_retry_count = 1 [(validate.rules).uint32 = {lte: 3}];

  // Fully qualified domain names for which Envoy will respond to DNS queries. By leaving this
  // list empty, Envoy will forward all queries to external resolvers
  repeated DnsVirtualDomain virtual_domains = 2;

  // This field serves to help Envoy determine whether it can authoritatively answer a query
  // for a name matching a suffix in this list. If the query name does not match a suffix in
  // this list, Envoy will forward the query to an upstream DNS server
  repeated type.matcher.v4alpha.StringMatcher known_suffixes = 3;
}