www.pudn.com > jnp-src.rar > DNS.java

/*
 * Java Network Programming, Second Edition
 * Merlin Hughes, Michael Shoffner, Derek Hamner
 * Manning Publications Company; ISBN 188477749X
 *
 * http://nitric.com/jnp/
 *
 * Copyright (c) 1997-1999 Merlin Hughes, Michael Shoffner, Derek Hamner;
 * all rights reserved; see license.txt for details.
 */

public final class DNS { 
  public static final int 
    DEFAULT_PORT = 53; 
 
  public static final int 
    TYPE_A = 1, // address 
    TYPE_NS = 2, // nameserver 
    TYPE_MD = 3, // mail domain 
    TYPE_MF = 4, // mail forwarder 
    TYPE_CNAME = 5, // canonical name 
    TYPE_SOA = 6, // start of authority 
    TYPE_MB = 7, // mail box 
    TYPE_MG = 8, // mail group 
    TYPE_MR = 9, // mail rename 
    TYPE_NULL = 10, // null 
    TYPE_WKS = 11, // well-known services 
    TYPE_PTR = 12, // pointer 
    TYPE_HINFO = 13, // host info 
    TYPE_MINFO = 14, // mail info 
    TYPE_MX = 15, // mail exchanger 
    TYPE_TXT = 16, // text 
    TYPE_AXFR = 252, // zone transfer request 
    TYPE_MAILB = 253, // mailbox request 
    TYPE_MAILA = 254, // mail agent request 
    TYPE_ANY = 255; // request any 
 
  public static final int 
    CLASS_IN = 1, // internet 
    CLASS_CS = 2, // csnet 
    CLASS_CH = 3, // chaos 
    CLASS_HS = 4, // hesiod 
    CLASS_ANY = 255; // request any 
 
  public static final int 
    SHIFT_QUERY = 15, 
    SHIFT_OPCODE = 11, 
    SHIFT_AUTHORITATIVE = 10, 
    SHIFT_TRUNCATED = 9, 
    SHIFT_RECURSE_PLEASE = 8, 
    SHIFT_RECURSE_AVAILABLE = 7, 
    SHIFT_RESERVED = 4, 
    SHIFT_RESPONSE_CODE = 0; 
 
  public static final int 
    OPCODE_QUERY = 0, 
    OPCODE_IQUERY = 1, 
    OPCODE_STATUS = 2; 
 
  private static final String[] typeNames = { 
    "Address", "NameServer", "MailDomain", "MailForwarder", 
    "CanonicalName", "StartOfAuthority", "MailBox", "MailGroup", 
    "MailRename", "Null", "WellKnownServices", "Pointer", 
    "HostInfo", "MailInfo", "MailExchanger", "Text" 
  }; 
   
  public static String typeName (int type) { 
    return ((type >= 1) && (type <= 16)) ? typeNames[type - 1] : "Unknown"; 
  } 
   
  private static final String[] codeNames = { 
    "Format error", "Server failure", "Name not known", 
    "Not implemented", "Refused" 
  }; 
   
  public static String codeName (int code) { 
    return ((code >= 1) && (code <= 5)) ? 
      codeNames[code - 1] : "Unknown error"; 
  } 
}