var getdns = require("getdns");

var options = {
    // Option for stub resolver context, deferring lookups to the upstream recursive servers.
    resolution_type: getdns.RESOLUTION_STUB,
    // Upstream recursive servers.
    upstream_recursive_servers: [
        // Example: Google Public DNS.
        "8.8.8.8",
        // Example: Your local DNS server.
        ["127.0.0.1", 53],
    ],
    // Request timeout time in milliseconds.
    timeout: 1000,
    // Always return DNSSEC status.
    return_dnssec_status: true
};

// Contexts can be reused for several lookups, but must be explicitly destroyed.
var context = getdns.createContext(options);

var callback = function(err, result) {
    if (err) {
        // If not null, err is an object with msg and code.
        // Code maps to a getdns.CALLBACK_XXXX (CANCEL, TIMEOUT, ERROR).
        console.error(err);
    } else {
        // Result is a response dictionary, see below for the format.
        // For context.address() simply use result.just_address_answers.
        // NOTE: optionally check if each reply is secured with DNSSEC.
        console.log(result.canonical_name, result.just_address_answers);
    }

    // When done with a context, it must be explicitly destroyed.
    // Can be done after all lookups/transactions have finished or beforeExit.
    context.destroy();
};

// NOTE: the extensions parameter is optional.
var extensions = {
  // NOTE: enforce DNSSEC security validation and return only secure replies.
  //dnssec_return_only_secure: true,
};

// Simple domain name-to-ip address lookup.
// Always returns both IPv4 and IPv6 results, if available.
var transactionId = context.address("wikipedia.org", extensions, callback);

{
  "answer_type": 800,
  "canonical_name": "getdnsapi.net.",
  "just_address_answers": [
    "2a04:b900:0:100::37",
    "185.49.141.37"
  ],
  "replies_full": [
    "<Buffer length 677>",
    "<Buffer length 677>"
  ],
  "replies_tree": [
    {
      "additional": [
        "<Removed lines 39>"
      ],
      "answer": [
        {
          "class": 1,
          "name": "getdnsapi.net.",
          "rdata": {
            "ipv6_address": "2a04:b900:0:100::37",
            "rdata_raw": "<Buffer length 16>"
          },
          "ttl": 450,
          "type": 28
        },
        {
          "class": 1,
          "name": "getdnsapi.net.",
          "rdata": {
            "algorithm": 7,
            "key_tag": 32852,
            "labels": 2,
            "original_ttl": 450,
            "rdata_raw": "<Buffer length 161>",
            "signature": "<Buffer length 128>",
            "signature_expiration": 1491862518,
            "signature_inception": 1490027744,
            "signers_name": "getdnsapi.net.",
            "type_covered": 28
          },
          "ttl": 450,
          "type": 46
        }
      ],
      "answer_type": 800,
      "authority": [
        "<Removed lines 48>"
      ],
      "canonical_name": "getdnsapi.net.",
      "dnssec_status": 400,
      "header": {
        "aa": 0,
        "ad": 1,
        "ancount": 2,
        "arcount": 3,
        "cd": 0,
        "id": 0,
        "nscount": 4,
        "opcode": 0,
        "qdcount": 1,
        "qr": 1,
        "ra": 1,
        "rcode": 0,
        "rd": 1,
        "tc": 0,
        "z": 0
      },
      "question": {
        "qclass": 1,
        "qname": "getdnsapi.net.",
        "qtype": 28
      }
    },
    {
      "additional": [
        "<Removed lines 69>"
      ],
      "answer_type": 800,
      "authority": [
        "<Removed lines 48>"
      ],
      "canonical_name": "getdnsapi.net.",
      "dnssec_status": 400,
      "header": {
        "aa": 0,
        "ad": 1,
        "ancount": 2,
        "arcount": 3,
        "cd": 0,
        "id": 0,
        "nscount": 4,
        "opcode": 0,
        "qdcount": 1,
        "qr": 1,
        "ra": 1,
        "rcode": 0,
        "rd": 1,
        "tc": 0,
        "z": 0
      },
      "question": {
        "qclass": 1,
        "qname": "getdnsapi.net.",
        "qtype": 1
      }
    }
  ],
  "status": 900
}

var dnssecSecureReplies = result.replies_tree.filter(function(reply) {
    return reply.dnssec_status === getdns.DNSSEC_SECURE;
});

// See also https://getdnsapi.net/documentation/spec/

// Contexts can be reused for several lookups, but must be explicitly destroyed.
// See context options below.
var context = getdns.createContext(options);

// When done with a context, it must be explicitly destroyed.
// Can be done after all lookups/transactions have finished or beforeExit.
context.destroy();

// Cancel a request before the callback has been called.
context.cancel(transactionId);

// Method parameter formats.
var domainName = "subdomain.example.org";
var ipAddress = "111.222.33.44";
var ipAddress = "2620:0:862:ed1a::1";

// https://getdnsapi.net/documentation/spec/#3-extensions
// Extensions are optional in the below method calls.
var extensions = {
  dnssec_return_only_secure: true
};

// There are 80+ predefined `RRTYPE_XXXX` constants.
// Examples: A, AAAA, CNAME, MX, TXT, TLSA, SSHFP, OPENPGPKEY, ...
var request_type = getdns.RRTYPE_MX;
var request_type = getdns.RRTYPE_SSHFP;

function callback(err, result, transactionId) {
  // err is either null (good result) or an object: { msg: "...", code: getdns.CALLBACK_XXXX (CANCEL, TIMEOUT, ERROR) }
  // result is null (bad result) or an object with the response dictionary format shown elsewhere in this documentation.
  // transactionId matches the one given when the lookup was initialized.
}

// For looking up any type of DNS record.
var transactionId = context.general(domainName, request_type, extensions, callback);

// For doing getaddrinfo()-like address lookups.
// Always returns both IPv4 and IPv6 results, if available.
var transactionId = context.address(domainName, extensions, callback);

// For getting results from SRV lookups.
var transactionId = context.service(domainName, extensions, callback);

// For doing getnameinfo()-like name lookups.
var transactionId = context.hostname(ipAddress, extensions, callback);

// Setting context properties.
// See also https://getdnsapi.net/documentation/spec/
// The following properties are available to set directly and can also
// be set in the options object passed to the constructor.
//
// Context objects support setting properties via similar to the C API.
// Example: this C function call would map to that JS context property:
getdns_context_set_timeout(context, 1000);
context.timeout = 1000;

// Switch DNS resolution/lookup mode:
//   - Recursive: all lookups performed locally directly to relevant nameservers.
//   - Stub: all lookups deferred to upstream resolvers.
// For backwards compatibility the deprecated context.stub is still supported.
context.resolution_type = getdns.RESOLUTION_RECURSING;
context.resolution_type = getdns.RESOLUTION_STUB;

// If acting as a stub resolver, provide an array of DNS servers:
//   - IP addresses as strings (assuming DNS port is 53).
//   - An array with an IP address as a string and a port number as an integer.
// For backwards compatibility the deprecated context.upstreams is still supported.
context.upstream_recursive_servers = [
  // Example: Google Public DNS.
  "8.8.8.8",
  // Example: Your local DNS server.
  ["127.0.0.1", 53],
];

// If acting as recursive resolver, enable or disable following CNAME/DNAME redirects.
context.follow_redirects = getdns.REDIRECTS_FOLLOW;
context.follow_redirects = getdns.REDIRECTS_DO_NOT_FOLLOW;

// Integer in milliseconds. The default is undefined.
context.timeout = 1000;

// Boolean. Switch between thread or forking mode in the underlying libunbound.
context.use_threads = false;

// Enable looking up DNSSEC status of each response.
// The status is stored in each result.replies_tree[...].dnssec_status with
// values from getdns.DNSSEC_XXXX (SECURE, BOGUS, INDETERMINATE, INSECURE, NOT_PERFORMED).
context.return_dnssec_status = true;

// DNS uses UDP by default, but can use TCP or TLS as well.
// Values from getdns.TRANSPORT_XXXX (UDP_FIRST_AND_FALL_BACK_TO_TCP, UDP_ONLY, TCP_ONLY, TCP_ONLY_KEEP_CONNECTIONS_OPEN, TLS_ONLY_KEEP_CONNECTIONS_OPEN, TLS_FIRST_AND_FALL_BACK_TO_TCP_KEEP_CONNECTIONS_OPEN, UDP, TCP, TLS).
context.dns_transport = getdns.TRANSPORT_TLS_FIRST_AND_FALL_BACK_TO_TCP_KEEP_CONNECTIONS_OPEN;

// The transports array contains an ordered list of transports that will be used for DNS lookups.
// Values from getdns.TRANSPORT_XXXX (UDP, TCP, TLS)
// The default is a list containing getdns.TRANSPORT_UDP then getdns.TRANSPORT_TCP.
context.dns_transport_list = [
  getdns.TRANSPORT_TLS,
  getdns.TRANSPORT_TCP,
  getdns.TRANSPORT_UDP
]

// Specifies number of milliseconds the API will leave an idle TCP or TLS connection open for.
// Idle means no outstanding responses and no pending queries. The default is 0.
context.idle_timeout = ...;

// Related to  Extension mechanisms for DNS (EDNS).
// The value is between 0 and 255; the default is 0.
context.edns_extended_rcode = 0;

// The value is between 0 and 255; the default is 0.
context.edns_version = 0;

// The value is between 0 and 1; the default is 0.
context.edns_do_bit = 0;

// The value is between 512 and 65535; when not set, outgoing values will adhere to the suggestions in RFC 6891 and may follow a scheme that uses multiple values to maximize receptivity..
context.edns_maximum_udp_payloadSize = ...;

// Specifies limit the number of outstanding DNS queries.
// The API will block itself from sending more queries if it is about to exceed this value, and instead keep those queries in an internal queue.
// The a value of 0 indicates that the number of outstanding DNS queries is unlimited.
context.limit_outstanding_queries = ...;

// The namespaces array contains an ordered list of namespaces that will be queried.
// Important: this context setting is ignored for the context.general() function; it is used for the other functions.
// Values from getdns.NAMESPACE_XXXX (DNS, LOCALNAMES, NETBIOS, MDNS, NIS).
// The default is determined by the OS.
context.namespaces = [
  getdns.NAMESPACE_XXXX,
  getdns.NAMESPACE_XXXX
];