switch from gethostbyname to getaddrinfo on POSIX systems

gethostbyname may return any combination of IPv4 and IPv6 addresses,
and it's not safe to assume the first address is IPv4, which is all
our code is currently prepared to handle.  In contrast, getaddrinfo
allows us to specify whether we want IPv4, IPv6, or both.

We should eventually make this switch on Windows as well, but the
status of getaddrinfo in Windows 2000 is not clear, and MinGW's
ws2tcpip.h only declares it for XP and above.

This commit also adds InetAddress.getByName for explicit DNS lookups.

classpath/java/net/InetAddress.java

@@ -0,0 +1,53 @@
+/* Copyright (c) 2010, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.net;
+
+import java.io.IOException;
+
+public class InetAddress {
+  private final String address;
+
+  private InetAddress(String address) {
+    this.address = address;
+  }
+
+  public String getHostAddress() {
+    return address;
+  }
+
+  public static InetAddress getByName(String name)
+    throws UnknownHostException
+  {
+    try {
+      Socket.init();
+    } catch (IOException e) {
+      UnknownHostException uhe = new UnknownHostException(name);
+      uhe.initCause(e);
+      throw uhe;
+    }
+
+    int address = ipv4AddressForName(name);
+    if (address == 0) {
+      throw new UnknownHostException(name);
+    } else {
+      return new InetAddress(ipv4AddressToString(address));
+    }
+  }
+
+  private static String ipv4AddressToString(int address) {
+    return (((address >>> 24)       ) + "." +
+            ((address >>> 16) & 0xFF) + "." +
+            ((address >>> 8 ) & 0xFF) + "." +
+            ((address       ) & 0xFF));
+  }
+
+  private static native int ipv4AddressForName(String name);
+}

classpath/java/net/Socket.java

@@ -10,6 +10,10 @@
 
 package java.net;
 
+import java.io.IOException;
+
 public abstract class Socket {
+  public static native void init() throws IOException;
+
   public abstract void setTcpNoDelay(boolean on) throws SocketException;
 }

classpath/java/net/UnknownHostException.java

@@ -0,0 +1,21 @@
+/* Copyright (c) 2010, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.net;
+
+import java.io.IOException;
+
+public class UnknownHostException extends IOException {
+  public UnknownHostException(String host) {
+    super(host);
+  }
+
+  public UnknownHostException() { }
+}

classpath/java/nio/channels/Selector.java

@@ -18,7 +18,7 @@ public abstract class Selector {
   protected final Set<SelectionKey> keys = new HashSet();
   protected final Set<SelectionKey> selectedKeys = new HashSet();
 
-  public static Selector open() {
+  public static Selector open() throws IOException {
     return new SocketSelector();
   }
   

classpath/java/nio/channels/ServerSocketChannel.java

@@ -15,11 +15,16 @@ import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
 import java.net.ServerSocket;
+import java.net.Socket;
 
 public class ServerSocketChannel extends SelectableChannel {
-  private final SocketChannel channel = new SocketChannel();
+  private final SocketChannel channel;
 
-  public static ServerSocketChannel open() {
+  private ServerSocketChannel() throws IOException {
+    channel = new SocketChannel();
+  }
+
+  public static ServerSocketChannel open() throws IOException {
     return new ServerSocketChannel();
   }
 
@@ -58,6 +63,8 @@ public class ServerSocketChannel extends SelectableChannel {
   }
 
   private int doListen(String host, int port) throws IOException {
+    Socket.init();
+
     return natDoListen(host, port);
   }
 

classpath/java/nio/channels/SocketChannel.java

@@ -26,7 +26,9 @@ public class SocketChannel extends SelectableChannel
   boolean connected = false;
   boolean blocking = true;
 
-  public static SocketChannel open() {
+  public static SocketChannel open() throws IOException {
+    Socket.init();
+
     return new SocketChannel();
   }
 

classpath/java/nio/channels/SocketSelector.java

@@ -12,13 +12,16 @@ package java.nio.channels;
 
 import java.io.IOException;
 import java.util.Iterator;
+import java.net.Socket;
 
 class SocketSelector extends Selector {
   protected long state;
   protected final Object lock = new Object();
   protected boolean woken = false;
 
-  public SocketSelector() {
+  public SocketSelector() throws IOException {
+    Socket.init();
+
     state = natInit();
   }