mcs/class/System/System.Net/Dns.cs

   1 // System.Net.Dns.cs
   2 //
   3 // Author: Mads Pultz (mpultz@diku.dk)
   4 // Author: Lawrence Pit (loz@cable.a2000.nl)
   5 //
   6 // (C) Mads Pultz, 2001
   7
   8 using System;
   9 using System.Net.Sockets;
  10 using System.Text;
  11 using System.Collections;
  12 using System.Threading;
  13 using System.Runtime.CompilerServices;
  14 using System.Runtime.Remoting.Messaging;
  15
  16 namespace System.Net {
  17         public sealed class Dns {
  18
  19                 private Dns () {}
  20                 static Dns ()
  21                 {
  22                         System.Net.Sockets.Socket.CheckProtocolSupport();
  23                 }
  24
  25                 private delegate IPHostEntry GetHostByNameCallback (string hostName);
  26                 private delegate IPHostEntry ResolveCallback (string hostName);
  27
  28                 public static IAsyncResult BeginGetHostByName (string hostName,
  29                         AsyncCallback requestCallback, object stateObject)
  30                 {
  31                         if (hostName == null)
  32                                 throw new ArgumentNullException();
  33
  34                         GetHostByNameCallback c = new GetHostByNameCallback (GetHostByName);
  35                         return c.BeginInvoke (hostName, requestCallback, stateObject);
  36                 }
  37
  38                 public static IAsyncResult BeginResolve (string hostName,
  39                         AsyncCallback requestCallback, object stateObject)
  40                 {
  41                         if (hostName == null)
  42                                 throw new ArgumentNullException();
  43                         ResolveCallback c = new ResolveCallback (Resolve);
  44                         return c.BeginInvoke (hostName, requestCallback, stateObject);
  45                 }
  46
  47                 public static IPHostEntry EndGetHostByName (IAsyncResult asyncResult) \r
  48                 {
  49                         if (asyncResult == null)
  50                                 throw new ArgumentNullException ("asyncResult");
  51                         AsyncResult async = (AsyncResult) asyncResult;
  52                         GetHostByNameCallback cb = (GetHostByNameCallback) async.AsyncDelegate;
  53                         asyncResult.AsyncWaitHandle.WaitOne ();
  54                         return cb.EndInvoke(asyncResult);
  55                 }
  56
  57                 public static IPHostEntry EndResolve (IAsyncResult asyncResult) \r
  58                 {
  59                         if (asyncResult == null)
  60                                 throw new ArgumentNullException ("asyncResult");
  61                         AsyncResult async = (AsyncResult) asyncResult;
  62                         ResolveCallback cb = (ResolveCallback) async.AsyncDelegate;
  63                         asyncResult.AsyncWaitHandle.WaitOne ();
  64                         return cb.EndInvoke(asyncResult);
  65                 }
  66
  67                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
  68                 private extern static bool GetHostByName_internal(string host, out string h_name, out string[] h_aliases, out string[] h_addr_list);
  69
  70                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
  71                 private extern static bool GetHostByAddr_internal(string addr, out string h_name, out string[] h_aliases, out string[] h_addr_list);
  72
  73                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
  74                 private extern static bool GetHostName_internal(out string h_name);
  75
  76                 private static IPHostEntry hostent_to_IPHostEntry(string h_name, string[] h_aliases, string[] h_addrlist) \r
  77                 {
  78                         IPHostEntry he = new IPHostEntry();
  79                         ArrayList addrlist = new ArrayList();
  80
  81                         he.HostName = h_name;
  82                         he.Aliases = h_aliases;
  83                         for(int i=0; i<h_addrlist.Length; i++) {
  84                                 IPAddress newAddress = IPAddress.Parse(h_addrlist[i]);
  85
  86                                 if( (Socket.SupportsIPv6 && newAddress.AddressFamily == AddressFamily.InterNetworkV6) ||
  87                                         (Socket.SupportsIPv4 && newAddress.AddressFamily == AddressFamily.InterNetwork) )
  88                                         addrlist.Add(newAddress);
  89                         }
  90
  91                         if(addrlist.Count == 0)
  92                                 throw new SocketException(11001);
  93
  94                         he.AddressList = addrlist.ToArray(typeof(IPAddress)) as IPAddress[];
  95                         return he;
  96                 }
  97
  98                 public static IPHostEntry GetHostByAddress(IPAddress address) \r
  99                 {
 100                         if (address == null)
 101                                 throw new ArgumentNullException();
 102                         return GetHostByAddress (address.ToString());
 103                 }
 104 \r
 105                 public static IPHostEntry GetHostByAddress(string address) \r
 106                 {
 107                         if (address == null)
 108                                 throw new ArgumentNullException();
 109
 110                         // Undocumented MS behavior: when called with IF_ANY,
 111                         // this should return the local host
 112                         if (address.Equals ("0.0.0.0"))
 113                                 return GetHostByAddress ("127.0.0.1");
 114
 115                         /// Must check the IP format, might send an exception if
 116                         /// invalid string.
 117                         IPAddress.Parse(address);
 118
 119                         string h_name;
 120                         string[] h_aliases, h_addrlist;
 121
 122                         bool ret = GetHostByAddr_internal(address, out h_name,
 123                                 out h_aliases,
 124                                 out h_addrlist);
 125                         if (!ret)
 126                                 throw new SocketException(11001);
 127
 128                         return(hostent_to_IPHostEntry(h_name, h_aliases,
 129                                 h_addrlist));
 130                 }
 131
 132                 public static IPHostEntry GetHostByName(string hostName) \r
 133                 {
 134                         if (hostName == null)
 135                                 throw new ArgumentNullException();
 136
 137                         string h_name;
 138                         string[] h_aliases, h_addrlist;
 139
 140                         bool ret = GetHostByName_internal(hostName, out h_name,
 141                                 out h_aliases,
 142                                 out h_addrlist);
 143                         if (ret == false)
 144                                 throw new SocketException(11001);
 145
 146                         return(hostent_to_IPHostEntry(h_name, h_aliases,
 147                                 h_addrlist));
 148                 }
 149
 150                 /// <summary>
 151                 /// This method returns the host name associated with the local host.
 152                 /// </summary>
 153                 public static string GetHostName() \r
 154                 {
 155                         string hostName;
 156
 157                         bool ret = GetHostName_internal(out hostName);
 158
 159                         if (ret == false)
 160                                 throw new SocketException(11001);
 161
 162                         return hostName;
 163                 }
 164
 165                 /// <summary>
 166                 /// This method resolves a DNS-style host name or IP
 167                 /// address.
 168                 /// </summary>
 169                 /// <param name=hostName>
 170                 /// A string containing either a DNS-style host name (e.g.
 171                 /// www.go-mono.com) or IP address (e.g. 129.250.184.233).
 172                 /// </param>
 173                 public static IPHostEntry Resolve(string hostName) \r
 174                 {
 175                         if (hostName == null)
 176                                 throw new ArgumentNullException();
 177
 178                         IPHostEntry ret = null;
 179
 180                         try {\r
 181                                 ret =  GetHostByAddress(hostName);\r
 182                         }
 183                         catch{}
 184
 185                         if(ret == null)\r
 186                                 ret =  GetHostByName(hostName);\r
 187
 188                         return ret;
 189                 }
 190         }
 191 }
 192