DNS query

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Revision as of 16:21, 29 July 2015 by Simple9371 (talk | contribs) (→‎{{header|Batch File}}: Edited so that sites with only one IP will be read also...)
DNS query
You are encouraged to solve this task according to the task description, using any language you may know.

DNS is an internet service that maps domain names, like rosettacode.org, to IP addresses, like

Use DNS to resolve www.kame.net to both IPv4 and IPv6 addresses. Print these addresses.


Works with: GNAT GPL version Any - package Gnat.Sockets supports only IPv4 as of Jun 2011

<lang Ada>with Ada.Text_IO; use Ada.Text_IO; with GNAT.Sockets; use GNAT.Sockets;

procedure DNSQuerying is

  Host         : Host_Entry_Type (1, 1);
  Inet_Addr_V4 : Inet_Addr_Type (Family_Inet);


  Host         := Get_Host_By_Name (Name => "www.kame.net");
  Inet_Addr_V4 := Addresses (Host);
  Put ("IPv4: " & Image (Value => Inet_Addr_V4));

end DNSQuerying;</lang>


This code uses Windows built-in 'nslookup' command (and a temporary file): <lang AutoHotkey>Url := "www.kame.net" , LogFile := "Ping_" A_Now ".log" Runwait, %comspec% /c nslookup %Url%>%LogFile%, , hide FileRead, Contents, %LogFile% FileDelete, %LogFile% RegExMatch(Contents,"Addresses:.+(`r?`n\s+.+)*",Match) MsgBox, % RegExReplace(Match,"(Addresses:|[ `t])")</lang>

Batch File

Uses NSLOOKUP and a temporary file, very similar to the AutoHotKey code. <lang dos>@echo off setlocal enabledelayedexpansion

set "Temp_File=%TMP%\NSLOOKUP_%RANDOM%.TMP" set "Domain=www.kame.net"

echo.Domain: %Domain% echo. echo.IP Addresses:

::The Main Processor nslookup %Domain% >"%Temp_File%" 2>nul for /f "tokens=*" %%A in ( 'findstr /B /C:"Address" "%Temp_File%" ^& findstr /B /C:" " "%Temp_File%"' ) do ( set data=%%A echo.!data:*s: =!|findstr /VBC:"192.168." /VBC:"" ) del /Q "%Temp_File%" echo. pause</lang>

Domain: www.kame.net

IP Addresses:

Press any key to continue . . .


<lang bbcbasic> name$ = "www.kame.net"

     AF_INET = 2
     AF_INET6 = 23
     SYS "LoadLibrary", "WS2_32.DLL" TO ws2%
     SYS "GetProcAddress", ws2%, "WSAStartup"  TO `WSAStartup`
     SYS "GetProcAddress", ws2%, "WSACleanup"  TO `WSACleanup`
     SYS "GetProcAddress", ws2%, "getaddrinfo" TO `getaddrinfo`
     DIM WSAdata{wVersion{l&,h&}, wHighVersion{l&,h&}, \
     \ szDescription&(WSADESCRIPTION_LEN), szSystemStatus&(WSASYS_STATUS_LEN), \
     \ iMaxSockets{l&,h&}, iMaxUdpDg{l&,h&}, lpVendorInfo%}
     DIM addrinfo{ai_flags%, ai_family%, ai_socktype%, ai_protocol%, \
     \      ai_addrlen%, lp_ai_canonname%, lp_ai_addr%, lp_ai_next%}
     DIM ipv4info{} = addrinfo{}, ipv6info{} = addrinfo{}
     DIM sockaddr_in{sin_family{l&,h&}, sin_port{l&,h&}, sin_addr&(3), sin_zero&(7)}
     DIM sockaddr_in6{sin6_family{l&,h&}, sin6_port{l&,h&}, sin6_flowinfo%, \
     \                sin6_addr&(15), sin6_scope_id%}
     SYS `WSAStartup`, &202, WSAdata{} TO res%
     IF res% ERROR 102, "WSAStartup failed"
     addrinfo.ai_family% = AF_INET
     SYS `getaddrinfo`, name$, 0, addrinfo{}, ^ipv4info{}+4 TO res%
     IF res% ERROR 103, "getaddrinfo failed"
     !(^sockaddr_in{}+4) = ipv4info.lp_ai_addr%
     PRINT "IPv4 address = " ;
     PRINT ;sockaddr_in.sin_addr&(0) "." sockaddr_in.sin_addr&(1) "." ;
     PRINT ;sockaddr_in.sin_addr&(2) "." sockaddr_in.sin_addr&(3)
     addrinfo.ai_family% = AF_INET6
     SYS `getaddrinfo`, name$, 0, addrinfo{}, ^ipv6info{}+4 TO res%
     IF res% ERROR 104, "getaddrinfo failed"
     !(^sockaddr_in6{}+4) = ipv6info.lp_ai_addr%
     PRINT "IPv6 address = " ;
     PRINT ;~sockaddr_in6.sin6_addr&(0) * 256 + sockaddr_in6.sin6_addr&(1) ":" ;
     PRINT ;~sockaddr_in6.sin6_addr&(2) * 256 + sockaddr_in6.sin6_addr&(3) ":" ;
     PRINT ;~sockaddr_in6.sin6_addr&(4) * 256 + sockaddr_in6.sin6_addr&(5) ":" ;
     PRINT ;~sockaddr_in6.sin6_addr&(6) * 256 + sockaddr_in6.sin6_addr&(7) ":" ;
     PRINT ;~sockaddr_in6.sin6_addr&(8) * 256 + sockaddr_in6.sin6_addr&(9) ":" ;
     PRINT ;~sockaddr_in6.sin6_addr&(10) * 256 + sockaddr_in6.sin6_addr&(11) ":" ;
     PRINT ;~sockaddr_in6.sin6_addr&(12) * 256 + sockaddr_in6.sin6_addr&(13) ":" ;
     PRINT ;~sockaddr_in6.sin6_addr&(14) * 256 + sockaddr_in6.sin6_addr&(15)
     SYS `WSACleanup`

</lang> Output:

IPv4 address =
IPv6 address = 2001:200:DFF:FFF1:216:3EFF:FEB1:44D7


This solution uses getaddrinfo(), a standard function from RFC 3493. This code resembles an example from getaddrinfo(3), the BSD manual page. Whereas the man page code connects to www.kame.net, this code only prints the numeric addresses.

<lang c>#include <sys/types.h>

  1. include <sys/socket.h>
  2. include <netdb.h> /* getaddrinfo, getnameinfo */
  3. include <stdio.h> /* fprintf, printf */
  4. include <stdlib.h> /* exit */
  5. include <string.h> /* memset */

int main() { struct addrinfo hints, *res, *res0; int error; char host[NI_MAXHOST];

/* * Request only one socket type from getaddrinfo(). Else we * would get both SOCK_DGRAM and SOCK_STREAM, and print two * copies of each numeric address. */ memset(&hints, 0, sizeof hints); hints.ai_family = PF_UNSPEC; /* IPv4, IPv6, or anything */ hints.ai_socktype = SOCK_DGRAM; /* Dummy socket type */

/* * Use getaddrinfo() to resolve "www.kame.net" and allocate * a linked list of addresses. */ error = getaddrinfo("www.kame.net", NULL, &hints, &res0); if (error) { fprintf(stderr, "%s\n", gai_strerror(error)); exit(1); }

/* Iterate the linked list. */ for (res = res0; res; res = res->ai_next) { /* * Use getnameinfo() to convert res->ai_addr to a * printable string. * * NI_NUMERICHOST means to present the numeric address * without doing reverse DNS to get a domain name. */ error = getnameinfo(res->ai_addr, res->ai_addrlen, host, sizeof host, NULL, 0, NI_NUMERICHOST);

if (error) { fprintf(stderr, "%s\n", gai_strerror(error)); } else { /* Print the numeric address. */ printf("%s\n", host); } }

/* Free the linked list. */ freeaddrinfo(res0);

return 0; }</lang>


Implementation takes a host name string as a parameter, and returns the IP addresses in a comma-delimited string. Note that a failed lookup throws a SocketException. <lang csharp>

       private string LookupDns(string s)
               System.Net.IPHostEntry ip = System.Net.Dns.GetHostEntry(s);
               string result = ip.AddressList[0].ToString();
               for (int i = 1; i < ip.AddressList.Length; ++i)
                   result += ", " + ip.AddressList[i].ToString();
               return result;
           catch (System.Net.Sockets.SocketException se)
               return se.Message;


Caché ObjectScript

<lang cos> Class Utils.Net [ Abstract ] {

ClassMethod QueryDNS(pHost As %String, Output ip As %List) As %Status { // some initialisation Set ip=$ListBuild()

// check host operating system and input parameters Set os=$Case($ZVersion(1), 1: "vms", 2: "win", 3: "*nx", : "") If (os="vms")||(os="") Quit $$$ERROR($$$GeneralError, "Not implemented.") If os="win" Set cmd="nslookup "_pHost If os="*nx" Set cmd="host "_pHost If $Match(pHost, "^([a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?\.)+[a-zA-Z]{2,6}$")=0 { Quit $$$ERROR($$$GeneralError, "Invalid host name.") }

// enable end-of-file flagging Do $System.Process.SetZEOF(1)

// invoke command Open cmd:"QR":15 If $Test { For i=1:1 { If i>100 Quit Use cmd Read row If $ZEOF Quit If os="win" Set os=$Select(row["Name:": "", 1: os) Continue Set ipv4=..GetIPAddr("ipv4", row) If $Length(ipv4) Set $List(ip, 4)=ipv4 Set ipv6=..GetIPAddr("ipv6", row) If $Length(ipv6) Set $List(ip, 6)=ipv6 } Close cmd }

// disable end-of-file flagging Do $System.Process.SetZEOF(0)

// finished If $ListData(ip, 4)=0, $ListData(ip, 6)=0 Quit $$$ERROR($$$GeneralError, "Lookup failed.") Quit $$$OK }

ClassMethod GetIPAddr(pType As %String = "", pRow As %String = "") As %String { If pType="ipv4" { Set pos=$Locate(pRow, "((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.|$)){4}") If pos Quit $Piece($Extract(pRow, pos, *), " ") } ElseIf pType="ipv6" { Set pos=$Locate(pRow, "([0-9A-Fa-f]{0,4}:){2,7}([0-9A-Fa-f]{1,4}$|((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.|$)){4})") If pos Quit $Piece($Extract(pRow, pos, *), " ") } Quit "" }

} </lang>

USER>Do ##class(Utils.Net).QueryDNS("www.kame.net", .ip)
USER>Write "IPv4 address = ", $ListGet(ip, 4, "Not found")
IPv4 address =
USER>Write "IPv6 address = ", $ListGet(ip, 6, "Not found")
IPv6 address = 2001:200:dff:fff1:216:3eff:feb1:44d7

USER>Do ##class(Utils.Net).QueryDNS("ipv6.google.com", .ip) 
USER>Write "IPv4 address = ", $ListGet(ip, 4, "Not found")
IPv4 address = Not found
USER>Write "IPv6 address = ", $ListGet(ip, 6, "Not found")
IPv6 address = 2a00:1450:400c:c05::93


<lang clojure>(import java.net.InetAddress java.net.Inet4Address java.net.Inet6Address)

(doseq [addr (InetAddress/getAllByName "www.kame.net")]

   (instance? Inet4Address addr) (println "IPv4:" (.getHostAddress addr))
   (instance? Inet6Address addr) (println "IPv6:" (.getHostAddress addr))))</lang>


IPv6: 2001:200:dff:fff1:216:3eff:feb1:44d7


<lang coffeescript>

  1. runs under node.js

dns = require 'dns'

dns.resolve4 'www.kame.net', (err, addresses) ->

 console.log 'IP4'
 console.log addresses

dns.resolve6 'www.kame.net', (err, addresses) ->

 console.log 'IP6'
 console.log addresses


Common Lisp

common lisp does not have a standard network api. the following examples are using native implementations

Works with: SBCL

<lang lisp>(sb-bsd-sockets:host-ent-addresses

     (sb-bsd-sockets:get-host-by-name "www.rosettacode.org"))

(#(71 19 147 227))</lang>

Works with: CMUCL

<lang lisp>(let ((hostname (extensions:lookup-host-entry "www.rosettacode.org")))

               (print (map 'list #'extensions:ip-string (host-entry-addr-list hostname))))

("")</lang> the usocket library contains a (get-hosts-by-name) function in all of its backends. unfortunately it does not expose the functions in its public interface. but since the license is MIT, it may be a suitable source to copy code for your own use.

Library: iolib
is a portable library that:
Works with: SBCL
Works with: CMUCL
Works with: Clisp
Works with: Clozure

<lang lisp>(iolib:lookup-hostname "www.kame.net" :ipv6 t)


(#/IOLIB.SOCKETS:IP/2001:200:dff:fff1:216:3eff:feb1:44d7) "orange.kame.net" (("orange.kame.net" . #/IOLIB.SOCKETS:IP/

("orange.kame.net" . #/IOLIB.SOCKETS:IP/2001:200:dff:fff1:216:3eff:feb1:44d7))</lang>


<lang d>import std.stdio, std.socket;

void main() {

   auto domain = "www.kame.net", port = "80";
   auto a = getAddressInfo(domain, port);
   writefln("IPv4 address for %s: %s", domain, a[0].address);
   a = getAddressInfo(domain, port, AddressFamily.INET6);
   writefln("IPv6 address for %s: %s", domain, a[0].address);


IPv4 address for www.kame.net:
IPv6 address for www.kame.net: [2001:200:dff:fff1:216:3eff:feb1:44d7]:80


The included Indy components wrap GetAddressInfo.

<lang Delphi>program DNSQuerying;



 IdGlobal, IdStackWindows;


 DOMAIN_NAME = 'www.kame.net';


 lStack: TIdStackWindows;


 lStack := TIdStackWindows.Create;
   Writeln('IPv4: ' + lStack.ResolveHost(DOMAIN_NAME));
   Writeln('IPv6: ' + lStack.ResolveHost(DOMAIN_NAME, Id_IPv6));



IPv6: 2001:200:DFF:FFF1:216:3EFF:FEB1:44D7


<lang go>package main

import (



func main() {

   if addrs, err := net.LookupHost("www.kame.net"); err == nil {
   } else {

}</lang> Output:

[ 2001:200:dff:fff1:216:3eff:feb1:44d7]


<lang groovy>def addresses = InetAddress.getAllByName('www.kame.net') println "IPv4: ${addresses.find { it instanceof Inet4Address }?.hostAddress}" println "IPv6: ${addresses.find { it instanceof Inet6Address }?.hostAddress}"</lang> Output:

IPv6: 2001:200:dff:fff1:216:3eff:feb1:44d7


<lang haskell>module Main where

import Network.Socket

getWebAddresses :: HostName -> IO [SockAddr] getWebAddresses host = do

 results <- getAddrInfo (Just defaultHints) (Just host) (Just "http")
 return [ addrAddress a | a <- results, addrSocketType a == Stream ]

showIPs :: HostName -> IO () showIPs host = do

 putStrLn $ "IP addresses for " ++ host ++ ":"
 addresses <- getWebAddresses host
 mapM_ (putStrLn . ("  "++) . show) addresses

main = showIPs "www.kame.net" </lang> Output:

IP addresses for www.kame.net:

Icon and Unicon

The following was tested only in Unicon:

<lang unicon> procedure main(A)

  host := gethost( A[1] | "www.kame.net") | stop("can't translate")
  write(host.name, ": ", host.addresses)

end </lang>

Sample Run:

--> dns

--> dns www.gogole.com


J currently doesn't have a native DNS implementation, and this task doesn't seem to be asking for us to implement DNS on top of UDP+TCP (a full implementation of DNS has to fall back to TCP for messages which cannot fit in a UDP packet).

Also, there's currently an issue with IPv6 DNS servers not being reachable, so that query did not resolve.


<lang J> 2!:0'dig -4 +short www.kame.net' orange.kame.net.

  2!:0'dig -6 +short www.kame.net'

|interface error | 2!:0'dig -6 +short www.kame.net'</lang>

Put differently: in the IPv4 DNS system, www.kame.net is currently a CNAME record for orange.kame.net which had the address

And, as mentioned above, the IPv6 DNS system was not reachable.


<lang java>import java.net.InetAddress; import java.net.Inet4Address; import java.net.Inet6Address; import java.net.UnknownHostException;

class DnsQuery {

   public static void main(String[] args) {
       try {
           InetAddress[] ipAddr = InetAddress.getAllByName("www.kame.net");
           for(int i=0; i < ipAddr.length ; i++) {
               if (ipAddr[i] instanceof Inet4Address) {
                   System.out.println("IPv4 : " + ipAddr[i].getHostAddress());
               } else if (ipAddr[i] instanceof Inet6Address) {
                   System.out.println("IPv6 : " + ipAddr[i].getHostAddress());
       } catch (UnknownHostException uhe) {
           System.err.println("unknown host");

} </lang> Output:

IPv4 :
IPv6 : 2001:200:dff:fff1:216:3eff:feb1:44d7


The DNS lookup methods in Lasso do not support IPv6 addresses at this time, only IPv4. <lang Lasso>dns_lookup('www.kame.net', -type='A')</lang>


<lang netrexx> /* NetRexx */ options replace format comments java crossref symbols nobinary

ir = InetAddress addresses = InetAddress[] InetAddress.getAllByName('www.kame.net') loop ir over addresses

 if ir <= Inet4Address then do
   say 'IPv4 :' ir.getHostAddress
 if ir <= Inet6Address then do
   say 'IPv6 :' ir.getHostAddress
 end ir


IPv4 :
IPv6 : 2001:200:dff:fff1:216:3eff:feb1:44d7


<lang newLISP>

(define (dnsLookup site , ipv)

   ;; captures current IPv mode
   (set 'ipv (net-ipv))
   ;; IPv mode agnostic lookup
   (println "IPv4: " (begin (net-ipv 4) (net-lookup site)))
   (println "IPv6: " (begin (net-ipv 6) (net-lookup site)))
   ;; returns newLISP to previous IPv mode
   (net-ipv ipv)


(dnsLookup "www.kame.net") </lang>

IPv6: 2001:200:dff:fff1:216:3eff:feb1:44d7


<lang ocaml>let dns_query ~host ~ai_family =

 let opts = [
   Unix.AI_FAMILY ai_family;
 ] in
 let addr_infos = Unix.getaddrinfo host "" opts in
 match addr_infos with
 | [] -> failwith "dns_query"
 | ai :: _ ->
   match ai.Unix.ai_addr with
   | Unix.ADDR_INET (addr, _) -> (Unix.string_of_inet_addr addr)
   | Unix.ADDR_UNIX addr -> failwith "addr_unix"

let () =

 let host = "www.kame.net" in
 Printf.printf "primary addresses of %s are:\n" host;
 Printf.printf " IPv4 address: %s\n" (dns_query host Unix.PF_INET);
 Printf.printf " IPv6 address: %s\n" (dns_query host Unix.PF_INET6);


Unfortunately IPv6 was only added to Perl 5.14, a relatively new version. <lang perl>require 5.014; # Older versions can't resolve IPv6 with just core Socket module

use Socket qw(getaddrinfo getnameinfo); my ($err, @res) = getaddrinfo("www.kame.net", 0,

               { protocol=>Socket::IPPROTO_TCP } );

die "getaddrinfo error: $err" if $err;

print getnameinfo($_->{addr}, Socket::NI_NUMERICHOST), "\n" for @res </lang>


Works for PHP5 (Windows > 5.3.0) <lang php><?php

 $ipv4_record = dns_get_record("www.kame.net",DNS_A);
 $ipv6_record = dns_get_record("www.kame.net",DNS_AAAA);
 print "ipv4: " . $ipv4_record[0]["ip"] . "\n";
 print "ipv6: " . $ipv6_record[0]["ipv6"] . "\n";



<lang PicoLisp>(make

  (in '(host "www.kame.net")
     (while (from "address ")
        (link (till "^J" T)) ) ) )</lang>


-> ("" "2001:200:dff:fff1:216:3eff:feb1:44d7")


<lang python>>>> import socket >>> ips = set(i[4][0] for i in socket.getaddrinfo('www.kame.net', 80)) >>> for ip in ips: print ip ... 2001:200:dff:fff1:216:3eff:feb1:44d7</lang>


<lang ruby>irb(main):001:0> require 'socket' => true irb(main):002:0> Addrinfo.getaddrinfo("www.kame.net", nil, nil, :DGRAM) \ irb(main):003:0* .map! { |ai| ai.ip_address } => ["", "2001:200:dff:fff1:216:3eff:feb1:44d7"]</lang>


R has no built-in function to accomplish the task, but with the help of the Rcpp package, it's possible to implement this functionality.

If the following is saved as dns.cpp:

<lang cpp>

  1. include <Rcpp.h>
  2. include <arpa/inet.h>
  3. include <sys/types.h>
  4. include <sys/socket.h>
  5. include <netdb.h>
  6. include <stdio.h>
  7. include <stdlib.h>
  8. include <string.h>

using namespace Rcpp ;

// export CharacterVector getNameInfo(std::string fqdn) {

 struct addrinfo hints, *res, *res0;

int error; char host[NI_MAXHOST];

 memset(&hints, 0, sizeof hints);

hints.ai_family = PF_UNSPEC; hints.ai_socktype = SOCK_DGRAM;

error = getaddrinfo(fqdn.c_str(), NULL, &hints, &res0); if (error) { return(NA_STRING); }

 int i = 0 ;

for (res = res0; res; res = res->ai_next) {

 	error = getnameinfo(res->ai_addr, res->ai_addrlen,

host, sizeof host, NULL, 0, NI_NUMERICHOST); if (!error) { i++ ; } }

 CharacterVector results(i) ;
 i = 0;
 for (res = res0; res; res = res->ai_next) {

error = getnameinfo(res->ai_addr, res->ai_addrlen, host, sizeof host, NULL, 0, NI_NUMERICHOST); if (!error) { results[i++] = host ; } }

 return(results) ;

} </lang>

It can be used to perform the task in R:

<lang R> library(Rcpp) sourceCpp("dns.cpp") getNameInfo("www.kame.net")

    1. [1] ""
    2. [2] "2001:200:dff:fff1:216:3eff:feb1:44d7"



The following finds an IPv4 address. Currently, the API does not support returning an IPv6 address.

<lang racket>

  1. lang racket

(require net/dns) (dns-get-address "" "www.kame.net") </lang>


This REXX version uses the Windows (DOS) PING command to resolve the domain name.

Execution note:   if the information for     PING   -6   ···     is blank, you may need to install   (on some
Microsoft Windows systems)   the IPV6 interface using the command:     IPV6 install <lang rexx>/*REXX program displays IPv4 and IPv6 addresses for a supplied domain name.*/ trace off /*don't show PING none─zero return code*/ parse arg tar . /*obtain optional domain name from C.L.*/ if tar== then tar='www.kame.net' /*Not specified? Then use the default.*/ tempFID='\TEMP\DNSQUERY.$$$.' /*define temp file to store the IPv4. */ pingOpts='-l 0 -n 1 -w 1' tar /*define options for the PING command. */

 do j=4  to 6  by 2                   /*handle  IPv4  and  IPv6  addresses.  */
 'PING' (-j)  pingOpts  ">"  tempFID  /*restrict PING's output to a minimum. */
 q=charin(tempFID,1,999)              /*read the output file from  PING  cmd.*/
 parse var  q   '['   IPA   ']'       /*parse  IP  address from the output.  */
 say 'IPv'j 'for domain name  '  tar  "  is  "  IPA   /*IPv4 or IPv6 address.*/
 call lineout tmp                     /* ◄──┬─◄  needed by some REXXes to    */
 end   /*j*/                          /*    └─◄         force file integrity.*/

'ERASE' tempFID /*clean up (delete) the temporary file.*/

                                      /*stick a fork in it,  we're all done. */</lang>

output   using the default input:

IPv4 for domain name   www.kame.net   is
IPv6 for domain name   www.kame.net   is   2001:200:dff:fff1:216:3eff:feb1:44d7


Library: Scala

<lang Scala>import java.net.{Inet4Address, Inet6Address, InetAddress}

object DnsQuery extends App {

 InetAddress.getAllByName("google.com").foreach {
   case x: Inet4Address => println(s"IPv4 : ${x.getHostAddress}")
   case x: Inet6Address => println(s"IPv6 : ${x.getHostAddress}")



Works with: Guile

<lang scheme>; Query DNS (define n (car (hostent:addr-list (gethost "www.kame.net"))))

Display address as IPv4 and IPv6

(display (inet-ntoa n))(newline) (display (inet-ntop AF_INET n))(newline) (display (inet-ntop AF_INET6 n))(newline)</lang>



The library socket.s7i defines the function inetSocketAddress, which returns an IPv4 address. It only returns an IPv6 address, when a host has no IPv4 address and the operating system supports IPv6. The function numericAddress is used to get the IP address of the specified host. <lang seed7>$ include "seed7_05.s7i";

 include "socket.s7i";

const proc: main is func

   writeln(numericAddress(inetSocketAddress("www.kame.net", 1024)));
 end func;</lang>



While Tcl does internally do address resolution, it doesn't directly support looking up addresses without actually connecting to them. This is left to support packages to provide. An additional complexity is that while the DNS protocol itself is defined to work with both TCP and UDP as the transport layer, Tcl only supports TCP sockets by default (because they have a stream model) whereas DNS is typically only deployed with UDP enabled.

Library: Tcllib (Package: dns)
Library: udp

<lang tcl>package require udp; # Query by UDP more widely supported, but requires external package package require dns

set host "www.kame.net" set v4 [dns::resolve $host -type A]; # Specifically get IPv4 address set v6 [dns::resolve $host -type AAAA]; # Specifically get IPv6 address while {[dns::status $v4] eq "connect" || [dns::status $v6] eq "connect"} {

   update; # Let queries complete

} puts "primary addresses of $host are:\n\tIPv4» [dns::address $v4]\n\tIPv6» [dns::address $v6]"</lang> Output:

primary addresses of www.kame.net are:
	IPv6» 2001:200:dff:fff1:216:3eff:feb1:44d7


The addrInfo method is just a front end to POSIX getaddrinfo. <lang zkl>zkl: Network.TCPClientSocket.addrInfo("www.kame.net") L("orange.kame.net",L("","2001:200:dff:fff1:216:3eff:feb1:44d7"))</lang>