验证IP地址(带掩码)

首先你要把你的IP地址转换成平面的 int s、 使用起来更容易:

String       s = "10.1.1.99";
Inet4Address a = (Inet4Address) InetAddress.getByName(s);
byte[]       b = a.getAddress();
int          i = ((b[0] & 0xFF) << 24) |
                 ((b[1] & 0xFF) << 16) |
                 ((b[2] & 0xFF) << 8)  |
                 ((b[3] & 0xFF) << 0);

一旦你的IP地址是普通的 内景 您可以做一些位运算来执行检查:

int subnet = 0x0A010100;   // 10.1.1.0/24
int bits   = 24;
int ip     = 0x0A010199;   // 10.1.1.99

// Create bitmask to clear out irrelevant bits. For 10.1.1.0/24 this is
// 0xFFFFFF00 -- the first 24 bits are 1's, the last 8 are 0's.
//
//     -1        == 0xFFFFFFFF
//     32 - bits == 8
//     -1 << 8   == 0xFFFFFF00
mask = -1 << (32 - bits)

if ((subnet & mask) == (ip & mask)) {
    // IP address is in the subnet.
}

public static boolean netMatch(String addr, String addr1){ //addr is subnet address and addr1 is ip address. Function will return true, if addr1 is within addr(subnet)

        String[] parts = addr.split("/");
        String ip = parts[0];
        int prefix;

        if (parts.length < 2) {
            prefix = 0;
        } else {
            prefix = Integer.parseInt(parts[1]);
        }

        Inet4Address a =null;
        Inet4Address a1 =null;
        try {
            a = (Inet4Address) InetAddress.getByName(ip);
            a1 = (Inet4Address) InetAddress.getByName(addr1);
        } catch (UnknownHostException e){}

        byte[] b = a.getAddress();
        int ipInt = ((b[0] & 0xFF) << 24) |
                         ((b[1] & 0xFF) << 16) |
                         ((b[2] & 0xFF) << 8)  |
                         ((b[3] & 0xFF) << 0);

        byte[] b1 = a1.getAddress();
        int ipInt1 = ((b1[0] & 0xFF) << 24) |
                         ((b1[1] & 0xFF) << 16) |
                         ((b1[2] & 0xFF) << 8)  |
                         ((b1[3] & 0xFF) << 0);

        int mask = ~((1 << (32 - prefix)) - 1);

        if ((ipInt & mask) == (ipInt1 & mask)) {
            return true;
        }
        else {
            return false;
        }
}

下面是一个以几种常见方式接受子网描述的版本,包括 IPv6协议 .

基于这里发布的其他代码。 打开 IPv4协议 地址它可能比在裸机上执行二进制操作的方法工作得慢 int 的。

package de.c3oe.tryanderror;
import java.math.BigInteger;
import java.net.InetAddress;
import java.net.UnknownHostException;

/**
 * @author c3oe.de, based on snippets from Scott Plante, John Kugelmann
 */
public class Subnet
{
    final private int bytesSubnetCount;
    final private BigInteger bigMask;
    final private BigInteger bigSubnetMasked;

    /** For use via format "192.168.0.0/24" or "2001:db8:85a3:880:0:0:0:0/57" */
    public Subnet( final InetAddress subnetAddress, final int bits )
    {
        this.bytesSubnetCount = subnetAddress.getAddress().length; // 4 or 16
        this.bigMask = BigInteger.valueOf( -1 ).shiftLeft( this.bytesSubnetCount*8 - bits ); // mask = -1 << 32 - bits
        this.bigSubnetMasked = new BigInteger( subnetAddress.getAddress() ).and( this.bigMask );
    }

    /** For use via format "192.168.0.0/255.255.255.0" or single address */
    public Subnet( final InetAddress subnetAddress, final InetAddress mask )
    {
        this.bytesSubnetCount = subnetAddress.getAddress().length;
        this.bigMask = null == mask ? BigInteger.valueOf( -1 ) : new BigInteger( mask.getAddress() ); // no mask given case is handled here.
        this.bigSubnetMasked = new BigInteger( subnetAddress.getAddress() ).and( this.bigMask );
    }

    /**
     * Subnet factory method.
     * @param subnetMask format: "192.168.0.0/24" or "192.168.0.0/255.255.255.0"
     *      or single address or "2001:db8:85a3:880:0:0:0:0/57"
     * @return a new instance
     * @throws UnknownHostException thrown if unsupported subnet mask.
     */
    public static Subnet createInstance( final String subnetMask )
            throws UnknownHostException
    {
        final String[] stringArr = subnetMask.split("/");
        if ( 2 > stringArr.length )
            return new Subnet( InetAddress.getByName( stringArr[ 0 ] ), (InetAddress)null );
        else if ( stringArr[ 1 ].contains(".") || stringArr[ 1 ].contains(":") )
            return new Subnet( InetAddress.getByName( stringArr[ 0 ] ), InetAddress.getByName( stringArr[ 1 ] ) );
        else
            return new Subnet( InetAddress.getByName( stringArr[ 0 ] ), Integer.parseInt( stringArr[ 1 ] ) );
    }

    public boolean isInNet( final InetAddress address )
    {
        final byte[] bytesAddress = address.getAddress();
        if ( this.bytesSubnetCount != bytesAddress.length )
            return false;
        final BigInteger bigAddress = new BigInteger( bytesAddress );
        return  bigAddress.and( this.bigMask ).equals( this.bigSubnetMasked );
    }

    @Override
    final public boolean equals( Object obj )
    {
        if ( ! (obj instanceof Subnet) )
            return false;
        final Subnet other = (Subnet)obj;
        return  this.bigSubnetMasked.equals( other.bigSubnetMasked ) &&
                this.bigMask.equals( other.bigMask ) &&
                this.bytesSubnetCount == other.bytesSubnetCount;
    }

    @Override
    final public int hashCode()
    {
        return this.bytesSubnetCount;
    }

    @Override
    public String toString()
    {
        final StringBuilder buf = new StringBuilder();
        bigInteger2IpString( buf, this.bigSubnetMasked, this.bytesSubnetCount );
        buf.append( '/' );
        bigInteger2IpString( buf, this.bigMask, this.bytesSubnetCount );
        return buf.toString();
    }

    static private void bigInteger2IpString( final StringBuilder buf, final BigInteger bigInteger, final int displayBytes )
    {
        final boolean isIPv4 = 4 == displayBytes;
        byte[] bytes = bigInteger.toByteArray();
        int diffLen = displayBytes - bytes.length;
        final byte fillByte = 0 > (int)bytes[ 0 ] ? (byte)0xFF : (byte)0x00;

        int integer;
        for ( int i = 0; i < displayBytes; i++ )
        {
            if ( 0 < i && ! isIPv4 && i % 2 == 0 )
                buf.append( ':' );
            else if ( 0 < i && isIPv4 )
                buf.append( '.' );
            integer = 0xFF & (i < diffLen ? fillByte : bytes[ i - diffLen ]);
            if ( ! isIPv4 && 0x10 > integer )
                buf.append( '0' );
            buf.append( isIPv4 ? integer : Integer.toHexString( integer ) );
        }
    }
}

这只是几行代码 open-source IPAddress Java library . 免责声明:我是IPAddress库的项目经理。

String subnetStr = "10.1.1.1/24";
String addrStr = "10.1.1.1";
IPAddress subnetAddress = new IPAddressString(subnetStr).getAddress();
IPAddress subnet = subnetAddress.toPrefixBlock();
IPAddress testAddress = new IPAddressString(addrStr).getAddress();
boolean result = subnet.contains(testAddress);
System.out.println(subnetAddress + " is in subnet " + subnet + " and " +
            (result ? "contains" : "does not contain") + " address " + testAddress);

输出:

10.1.1.1/24 is in subnet 10.1.1.0/24 and contains address 10.1.1.1

感谢John Kugelman——我用他的代码片段创建了这个类。

package bs;

import java.net.Inet4Address;
import java.net.InetAddress;
import java.net.UnknownHostException;

/**
 * Represents an IP range based on an address/mask.
 * @author Scott Plante, using code snippets by John Kugelman.
 */
public class IPMask
{
  public static void main(String args[]) 
      throws UnknownHostException
  {
    IPMask ipmask;

    ipmask = IPMask.getIPMask("192.168.20.32/24");
    System.out.println("Checking "+ipmask+"...");

    test(ipmask, "192.168.20.31 ", true);
    test(ipmask, "192.168.20.32 ", true);
    test(ipmask, "192.168.20.33 ", true);
    test(ipmask, "192.168.20.34 ", true);
    test(ipmask, "192.168.20.35 ", true);
    test(ipmask, "192.168.20.36 ", true);
    test(ipmask, "192.168.20.254", true);
    test(ipmask, "192.168.20.157", true);
    test(ipmask, "192.168.21.1  ", false);
    test(ipmask, "192.168.19.255", false);
    test(ipmask, "192.168.24.1  ", false);

    ipmask = IPMask.getIPMask("192.168.20.32/31");
    System.out.println("Checking "+ipmask+"...");

    test(ipmask, "192.168.20.31 ", false);
    test(ipmask, "192.168.20.32 ", true);
    test(ipmask, "192.168.20.33 ", true);
    test(ipmask, "192.168.20.34 ", false);
    test(ipmask, "192.168.20.35 ", false);
    test(ipmask, "192.168.20.36 ", false);
    test(ipmask, "192.168.20.254", false);
    test(ipmask, "192.168.20.157", false);
    test(ipmask, "192.168.21.1  ", false);
    test(ipmask, "192.168.19.255", false);
    test(ipmask, "192.168.24.1  ", false);

    ipmask = IPMask.getIPMask("192.168.20.32/23");
    System.out.println("Checking "+ipmask+"...");

    test(ipmask, "192.168.20.31 ", true);
    test(ipmask, "192.168.20.32 ", true);
    test(ipmask, "192.168.20.33 ", true);
    test(ipmask, "192.168.20.254", true);
    test(ipmask, "192.168.21.254", true);
    test(ipmask, "192.168.19.255", false);
    test(ipmask, "192.168.24.1  ", false);

  }

  public static void test(IPMask ipmask, String addr, boolean expect) 
      throws UnknownHostException
  {
    boolean got = ipmask.matches(addr);
    System.out.println(addr + "\t(" + expect + ") ?\t"+got
        + "\t" + (got==expect?"":"!!!!!!!!"));
  }

  private Inet4Address i4addr;
  private byte maskCtr;

  private int addrInt;
  private int maskInt;

  public IPMask(Inet4Address i4addr, byte mask)
  {
    this.i4addr = i4addr;
    this.maskCtr = mask;

    this.addrInt = addrToInt(i4addr);
    this.maskInt = ~((1 << (32 - maskCtr)) - 1);
  }

  /** IPMask factory method. 
   * 
   * @param addrSlashMask IP/Mask String in format "nnn.nnn.nnn.nnn/mask". If 
   *    the "/mask" is omitted, "/32" (just the single address) is assumed.
   * @return a new IPMask
   * @throws UnknownHostException if address part cannot be parsed by 
   *    InetAddress
   */
  public static IPMask getIPMask(String addrSlashMask) 
      throws UnknownHostException
  {
    int pos = addrSlashMask.indexOf('/');
    String addr;
    byte maskCtr;
    if (pos==-1)
    {
      addr = addrSlashMask;
      maskCtr = 32;
    }
    else
    { 
      addr = addrSlashMask.substring(0, pos);
      maskCtr = Byte.parseByte(addrSlashMask.substring(pos + 1));
    }
    return new IPMask((Inet4Address) InetAddress.getByName(addr), maskCtr);
  }

 /** Test given IPv4 address against this IPMask object.
   * 
   * @param testAddr address to check.
   * @return true if address is in the IP Mask range, false if not.
   */  
  public boolean matches(Inet4Address testAddr)
  {
    int testAddrInt = addrToInt(testAddr);   
    return ((addrInt & maskInt) == (testAddrInt & maskInt));
  }

/** Convenience method that converts String host to IPv4 address.
   * 
   * @param addr IP address to match in nnn.nnn.nnn.nnn format or hostname.
   * @return true if address is in the IP Mask range, false if not.
   * @throws UnknownHostException if the string cannot be decoded.
   */
  public boolean matches(String addr) 
      throws UnknownHostException
  {
    return matches((Inet4Address)InetAddress.getByName(addr));
  }

/** Converts IPv4 address to integer representation.
   */
  private static int addrToInt(Inet4Address i4addr)
  {
    byte[] ba = i4addr.getAddress();  
    return (ba[0]       << 24) 
        | ((ba[1]&0xFF) << 16) 
        | ((ba[2]&0xFF) << 8) 
        |  (ba[3]&0xFF);
  }

  @Override
  public String toString()
  {
    return "IPMask(" + i4addr.getHostAddress() + "/" + maskCtr + ")";
  }

  @Override
  public boolean equals(Object obj)
  {
    if (obj == null)
      return false;
    if (getClass() != obj.getClass())
      return false;
    final IPMask that = (IPMask) obj;    
    return (this.addrInt == that.addrInt && this.maskInt == that.maskInt);
  }

  @Override
  public int hashCode()
  {
    return this.maskInt + this.addrInt;
  }

}

我确实需要在他的代码中为int转换添加一个掩码:

Inet4Address a = (Inet4Address) InetAddress.getByName("192.192.192.192");
byte[]       b = a.getAddress();
int          i = (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | (b[3] << 0);
System.out.println(Integer.toHexString(i));
System.out.println(Integer.toHexString(addrToInt(a)));

产生:

ffffffc0
c0c0c0c0

在我的系统上:

$> uname -a
Linux guin 2.6.37.6-0.5-desktop #1 SMP PREEMPT 2011-04-25 21:48:33 +0200 x86_64 x86_64 x86_64 GNU/Linux
$> java -version
java version "1.6.0_25"
Java(TM) SE Runtime Environment (build 1.6.0_25-b06)
Java HotSpot(TM) 64-Bit Server VM (build 20.0-b11, mixed mode)
$> 

可以从上述类中删除main和test方法。它们改编自单元测试代码,为了简单起见添加在这里。

有 commons-ip-math 我相信图书馆做得很好。请注意,截至2019年5月,图书馆已有2年没有任何更新(可能是它已经非常成熟的图书馆)。它在上可用 maven-central

它支持同时使用IPv4和IPv6地址。他们的简要文档中有一些示例,说明如何检查地址是否在 IPv4 和 IPv6

IPv4范围检查示例:

        String input1 = "10.1.1.1";
        Ipv4 ipv41 = Ipv4.parse(input1);

        // Using CIDR notation to specify the networkID and netmask
        Ipv4Range range = Ipv4Range.parse("10.1.1.1/32");
        boolean result = range.contains(ipv41);
        System.out.println(result); //true

        String input2 = "10.1.1.1";
        Ipv4 ipv42 = Ipv4.parse(input2);

        // Specifying the range with a start and end.
        Ipv4 start = Ipv4.of("10.1.1.1");
        Ipv4 end = Ipv4.of("10.1.1.1");
        range = Ipv4Range.from(start).to(end);

        result = range.contains(ipv42); //true
        System.out.println(result);