http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5. 
public class org.bouncycastle.util.IPAddress
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: org.bouncycastle.util.IPAddress
  super_class: java.lang.Object
{
  public void <init>();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.bouncycastle.util.IPAddress this
         0: .line 3
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // org.bouncycastle.util.IPAddress this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/bouncycastle/util/IPAddress;

  public static boolean isValid(java.lang.String);
    descriptor: (Ljava/lang/String;)Z
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // java.lang.String address
         0: .line 15
            aload 0 /* address */
            invokestatic org.bouncycastle.util.IPAddress.isValidIPv4:(Ljava/lang/String;)Z
            ifne 1
            aload 0 /* address */
            invokestatic org.bouncycastle.util.IPAddress.isValidIPv6:(Ljava/lang/String;)Z
            ifne 1
            iconst_0
            ireturn
      StackMap locals:
      StackMap stack:
         1: iconst_1
            ireturn
        end local 0 // java.lang.String address
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    2     0  address  Ljava/lang/String;
    MethodParameters:
         Name  Flags
      address  

  public static boolean isValidWithNetMask(java.lang.String);
    descriptor: (Ljava/lang/String;)Z
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // java.lang.String address
         0: .line 28
            aload 0 /* address */
            invokestatic org.bouncycastle.util.IPAddress.isValidIPv4WithNetmask:(Ljava/lang/String;)Z
            ifne 1
            aload 0 /* address */
            invokestatic org.bouncycastle.util.IPAddress.isValidIPv6WithNetmask:(Ljava/lang/String;)Z
            ifne 1
            iconst_0
            ireturn
      StackMap locals:
      StackMap stack:
         1: iconst_1
            ireturn
        end local 0 // java.lang.String address
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    2     0  address  Ljava/lang/String;
    MethodParameters:
         Name  Flags
      address  

  public static boolean isValidIPv4(java.lang.String);
    descriptor: (Ljava/lang/String;)Z
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=3, locals=6, args_size=1
        start local 0 // java.lang.String address
         0: .line 41
            aload 0 /* address */
            invokevirtual java.lang.String.length:()I
            ifne 2
         1: .line 43
            iconst_0
            ireturn
         2: .line 47
      StackMap locals:
      StackMap stack:
            iconst_0
            istore 2 /* octets */
        start local 2 // int octets
         3: .line 49
            new java.lang.StringBuilder
            dup
            aload 0 /* address */
            invokestatic java.lang.String.valueOf:(Ljava/lang/Object;)Ljava/lang/String;
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            ldc "."
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
            astore 3 /* temp */
        start local 3 // java.lang.String temp
         4: .line 52
            iconst_0
            istore 5 /* start */
        start local 5 // int start
         5: .line 53
            goto 16
        start local 4 // int pos
         6: .line 56
      StackMap locals: java.lang.String top int java.lang.String int int
      StackMap stack:
            iload 2 /* octets */
            iconst_4
            if_icmpne 8
         7: .line 58
            iconst_0
            ireturn
         8: .line 62
      StackMap locals:
      StackMap stack:
            aload 3 /* temp */
            iload 5 /* start */
            iload 4 /* pos */
            invokevirtual java.lang.String.substring:(II)Ljava/lang/String;
            invokestatic java.lang.Integer.parseInt:(Ljava/lang/String;)I
            istore 1 /* octet */
        start local 1 // int octet
         9: .line 63
            goto 12
        end local 1 // int octet
        10: .line 64
      StackMap locals:
      StackMap stack: java.lang.NumberFormatException
            pop
        11: .line 66
            iconst_0
            ireturn
        start local 1 // int octet
        12: .line 68
      StackMap locals: java.lang.String int int java.lang.String int int
      StackMap stack:
            iload 1 /* octet */
            iflt 13
            iload 1 /* octet */
            sipush 255
            if_icmple 14
        13: .line 70
      StackMap locals:
      StackMap stack:
            iconst_0
            ireturn
        14: .line 72
      StackMap locals:
      StackMap stack:
            iload 4 /* pos */
            iconst_1
            iadd
            istore 5 /* start */
        15: .line 73
            iinc 2 /* octets */ 1
        end local 4 // int pos
        end local 1 // int octet
        16: .line 53
      StackMap locals: java.lang.String top int java.lang.String top int
      StackMap stack:
            iload 5 /* start */
            aload 3 /* temp */
            invokevirtual java.lang.String.length:()I
            if_icmpge 20
        17: .line 54
            aload 3 /* temp */
            bipush 46
            iload 5 /* start */
            invokevirtual java.lang.String.indexOf:(II)I
            dup
            istore 4 /* pos */
        start local 4 // int pos
        18: iload 5 /* start */
        19: .line 53
            if_icmpgt 6
        end local 4 // int pos
        20: .line 76
      StackMap locals:
      StackMap stack:
            iload 2 /* octets */
            iconst_4
            if_icmpne 21
            iconst_1
            ireturn
      StackMap locals:
      StackMap stack:
        21: iconst_0
            ireturn
        end local 5 // int start
        end local 3 // java.lang.String temp
        end local 2 // int octets
        end local 0 // java.lang.String address
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0   22     0  address  Ljava/lang/String;
            9   10     1    octet  I
           12   16     1    octet  I
            3   22     2   octets  I
            4   22     3     temp  Ljava/lang/String;
            6   16     4      pos  I
           18   20     4      pos  I
            5   22     5    start  I
      Exception table:
        from    to  target  type
           8     9      10  Class java.lang.NumberFormatException
    MethodParameters:
         Name  Flags
      address  

  public static boolean isValidIPv4WithNetmask(java.lang.String);
    descriptor: (Ljava/lang/String;)Z
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=3, locals=3, args_size=1
        start local 0 // java.lang.String address
         0: .line 82
            aload 0 /* address */
            ldc "/"
            invokevirtual java.lang.String.indexOf:(Ljava/lang/String;)I
            istore 1 /* index */
        start local 1 // int index
         1: .line 83
            aload 0 /* address */
            iload 1 /* index */
            iconst_1
            iadd
            invokevirtual java.lang.String.substring:(I)Ljava/lang/String;
            astore 2 /* mask */
        start local 2 // java.lang.String mask
         2: .line 85
            iload 1 /* index */
            ifle 5
            aload 0 /* address */
            iconst_0
            iload 1 /* index */
            invokevirtual java.lang.String.substring:(II)Ljava/lang/String;
            invokestatic org.bouncycastle.util.IPAddress.isValidIPv4:(Ljava/lang/String;)Z
            ifeq 5
         3: .line 86
            aload 2 /* mask */
            invokestatic org.bouncycastle.util.IPAddress.isValidIPv4:(Ljava/lang/String;)Z
            ifne 4
            aload 2 /* mask */
            bipush 32
            invokestatic org.bouncycastle.util.IPAddress.isMaskValue:(Ljava/lang/String;I)Z
            ifeq 5
         4: .line 85
      StackMap locals: int java.lang.String
      StackMap stack:
            iconst_1
            ireturn
      StackMap locals:
      StackMap stack:
         5: iconst_0
            ireturn
        end local 2 // java.lang.String mask
        end local 1 // int index
        end local 0 // java.lang.String address
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    6     0  address  Ljava/lang/String;
            1    6     1    index  I
            2    6     2     mask  Ljava/lang/String;
    MethodParameters:
         Name  Flags
      address  

  public static boolean isValidIPv6WithNetmask(java.lang.String);
    descriptor: (Ljava/lang/String;)Z
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=3, locals=3, args_size=1
        start local 0 // java.lang.String address
         0: .line 92
            aload 0 /* address */
            ldc "/"
            invokevirtual java.lang.String.indexOf:(Ljava/lang/String;)I
            istore 1 /* index */
        start local 1 // int index
         1: .line 93
            aload 0 /* address */
            iload 1 /* index */
            iconst_1
            iadd
            invokevirtual java.lang.String.substring:(I)Ljava/lang/String;
            astore 2 /* mask */
        start local 2 // java.lang.String mask
         2: .line 95
            iload 1 /* index */
            ifle 5
            aload 0 /* address */
            iconst_0
            iload 1 /* index */
            invokevirtual java.lang.String.substring:(II)Ljava/lang/String;
            invokestatic org.bouncycastle.util.IPAddress.isValidIPv6:(Ljava/lang/String;)Z
            ifeq 5
         3: .line 96
            aload 2 /* mask */
            invokestatic org.bouncycastle.util.IPAddress.isValidIPv6:(Ljava/lang/String;)Z
            ifne 4
            aload 2 /* mask */
            sipush 128
            invokestatic org.bouncycastle.util.IPAddress.isMaskValue:(Ljava/lang/String;I)Z
            ifeq 5
         4: .line 95
      StackMap locals: int java.lang.String
      StackMap stack:
            iconst_1
            ireturn
      StackMap locals:
      StackMap stack:
         5: iconst_0
            ireturn
        end local 2 // java.lang.String mask
        end local 1 // int index
        end local 0 // java.lang.String address
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    6     0  address  Ljava/lang/String;
            1    6     1    index  I
            2    6     2     mask  Ljava/lang/String;
    MethodParameters:
         Name  Flags
      address  

  private static boolean isMaskValue(java.lang.String, int);
    descriptor: (Ljava/lang/String;I)Z
    flags: (0x000a) ACC_PRIVATE, ACC_STATIC
    Code:
      stack=2, locals=3, args_size=2
        start local 0 // java.lang.String component
        start local 1 // int size
         0: .line 103
            aload 0 /* component */
            invokestatic java.lang.Integer.parseInt:(Ljava/lang/String;)I
            istore 2 /* value */
        start local 2 // int value
         1: .line 105
            iload 2 /* value */
            iflt 2
            iload 2 /* value */
            iload 1 /* size */
            if_icmpgt 2
            iconst_1
            ireturn
      StackMap locals: int
      StackMap stack:
         2: iconst_0
         3: ireturn
        end local 2 // int value
         4: .line 107
      StackMap locals: java.lang.String int
      StackMap stack: java.lang.NumberFormatException
            pop
         5: .line 109
            iconst_0
            ireturn
        end local 1 // int size
        end local 0 // java.lang.String component
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    6     0  component  Ljava/lang/String;
            0    6     1       size  I
            1    4     2      value  I
      Exception table:
        from    to  target  type
           0     3       4  Class java.lang.NumberFormatException
    MethodParameters:
           Name  Flags
      component  
      size       

  public static boolean isValidIPv6(java.lang.String);
    descriptor: (Ljava/lang/String;)Z
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=3, locals=8, args_size=1
        start local 0 // java.lang.String address
         0: .line 123
            aload 0 /* address */
            invokevirtual java.lang.String.length:()I
            ifne 2
         1: .line 125
            iconst_0
            ireturn
         2: .line 129
      StackMap locals:
      StackMap stack:
            iconst_0
            istore 2 /* octets */
        start local 2 // int octets
         3: .line 131
            new java.lang.StringBuilder
            dup
            aload 0 /* address */
            invokestatic java.lang.String.valueOf:(Ljava/lang/Object;)Ljava/lang/String;
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            ldc ":"
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
            astore 3 /* temp */
        start local 3 // java.lang.String temp
         4: .line 132
            iconst_0
            istore 4 /* doubleColonFound */
        start local 4 // boolean doubleColonFound
         5: .line 134
            iconst_0
            istore 6 /* start */
        start local 6 // int start
         6: .line 135
            goto 27
        start local 5 // int pos
         7: .line 138
      StackMap locals: java.lang.String top int java.lang.String int int int
      StackMap stack:
            iload 2 /* octets */
            bipush 8
            if_icmpne 9
         8: .line 140
            iconst_0
            ireturn
         9: .line 143
      StackMap locals:
      StackMap stack:
            iload 6 /* start */
            iload 5 /* pos */
            if_icmpeq 22
        10: .line 145
            aload 3 /* temp */
            iload 6 /* start */
            iload 5 /* pos */
            invokevirtual java.lang.String.substring:(II)Ljava/lang/String;
            astore 7 /* value */
        start local 7 // java.lang.String value
        11: .line 147
            iload 5 /* pos */
            aload 3 /* temp */
            invokevirtual java.lang.String.length:()I
            iconst_1
            isub
            if_icmpne 16
            aload 7 /* value */
            bipush 46
            invokevirtual java.lang.String.indexOf:(I)I
            ifle 16
        12: .line 149
            aload 7 /* value */
            invokestatic org.bouncycastle.util.IPAddress.isValidIPv4:(Ljava/lang/String;)Z
            ifne 14
        13: .line 151
            iconst_0
            ireturn
        14: .line 154
      StackMap locals: java.lang.String
      StackMap stack:
            iinc 2 /* octets */ 1
        15: .line 155
            goto 25
        16: .line 160
      StackMap locals:
      StackMap stack:
            aload 3 /* temp */
            iload 6 /* start */
            iload 5 /* pos */
            invokevirtual java.lang.String.substring:(II)Ljava/lang/String;
            bipush 16
            invokestatic java.lang.Integer.parseInt:(Ljava/lang/String;I)I
            istore 1 /* octet */
        start local 1 // int octet
        17: .line 161
            goto 20
        end local 1 // int octet
        18: .line 162
      StackMap locals:
      StackMap stack: java.lang.NumberFormatException
            pop
        19: .line 164
            iconst_0
            ireturn
        start local 1 // int octet
        20: .line 166
      StackMap locals: java.lang.String int int java.lang.String int int int java.lang.String
      StackMap stack:
            iload 1 /* octet */
            iflt 21
            iload 1 /* octet */
            ldc 65535
            if_icmple 25
        21: .line 168
      StackMap locals:
      StackMap stack:
            iconst_0
            ireturn
        end local 7 // java.lang.String value
        end local 1 // int octet
        22: .line 174
      StackMap locals: java.lang.String top int java.lang.String int int int
      StackMap stack:
            iload 5 /* pos */
            iconst_1
            if_icmpeq 24
            iload 5 /* pos */
            aload 3 /* temp */
            invokevirtual java.lang.String.length:()I
            iconst_1
            isub
            if_icmpeq 24
            iload 4 /* doubleColonFound */
            ifeq 24
        23: .line 176
            iconst_0
            ireturn
        24: .line 178
      StackMap locals:
      StackMap stack:
            iconst_1
            istore 4 /* doubleColonFound */
        25: .line 180
      StackMap locals:
      StackMap stack:
            iload 5 /* pos */
            iconst_1
            iadd
            istore 6 /* start */
        26: .line 181
            iinc 2 /* octets */ 1
        end local 5 // int pos
        27: .line 135
      StackMap locals: java.lang.String top int java.lang.String int top int
      StackMap stack:
            iload 6 /* start */
            aload 3 /* temp */
            invokevirtual java.lang.String.length:()I
            if_icmpge 31
        28: .line 136
            aload 3 /* temp */
            bipush 58
            iload 6 /* start */
            invokevirtual java.lang.String.indexOf:(II)I
            dup
            istore 5 /* pos */
        start local 5 // int pos
        29: iload 6 /* start */
        30: .line 135
            if_icmpge 7
        end local 5 // int pos
        31: .line 184
      StackMap locals:
      StackMap stack:
            iload 2 /* octets */
            bipush 8
            if_icmpeq 32
            iload 4 /* doubleColonFound */
            ifne 32
            iconst_0
            ireturn
      StackMap locals:
      StackMap stack:
        32: iconst_1
            ireturn
        end local 6 // int start
        end local 4 // boolean doubleColonFound
        end local 3 // java.lang.String temp
        end local 2 // int octets
        end local 0 // java.lang.String address
      LocalVariableTable:
        Start  End  Slot              Name  Signature
            0   33     0           address  Ljava/lang/String;
           17   18     1             octet  I
           20   22     1             octet  I
            3   33     2            octets  I
            4   33     3              temp  Ljava/lang/String;
            5   33     4  doubleColonFound  Z
            7   27     5               pos  I
           29   31     5               pos  I
            6   33     6             start  I
           11   22     7             value  Ljava/lang/String;
      Exception table:
        from    to  target  type
          16    17      18  Class java.lang.NumberFormatException
    MethodParameters:
         Name  Flags
      address  
}
SourceFile: "IPAddress.java"