Android How to - Check if it is valid IPv4 or IPv6 Address

Question

We would like to know how to check if it is valid IPv4 or IPv6 Address.
Answer

/*from w w  w .  j  av a2  s  .com*/
//package org.bouncycastle.util;

class IPAddress {
  /**
   * Validate the given IPv4 or IPv6 address.
   *
   * @param address
   *          the IP address as a String.
   *
   * @return true if a valid address, false otherwise
   */
  public static boolean isValid(String address) {
    return isValidIPv4(address) || isValidIPv6(address);
  }

  /**
   * Validate the given IPv4 or IPv6 address and netmask.
   *
   * @param address
   *          the IP address as a String.
   *
   * @return true if a valid address with netmask, false otherwise
   */
  public static boolean isValidWithNetMask(String address) {
    return isValidIPv4WithNetmask(address) || isValidIPv6WithNetmask(address);
  }

  /**
   * Validate the given IPv4 address.
   * 
   * @param address
   *          the IP address as a String.
   *
   * @return true if a valid IPv4 address, false otherwise
   */
  public static boolean isValidIPv4(String address) {
    if (address.length() == 0) {
      return false;
    }

    int octet;
    int octets = 0;

    String temp = address + ".";

    int pos;
    int start = 0;
    while (start < temp.length() && (pos = temp.indexOf('.', start)) > start) {
      if (octets == 4) {
        return false;
      }
      try {
        octet = Integer.parseInt(temp.substring(start, pos));
      } catch (NumberFormatException ex) {
        return false;
      }
      if (octet < 0 || octet > 255) {
        return false;
      }
      start = pos + 1;
      octets++;
    }

    return octets == 4;
  }

  public static boolean isValidIPv4WithNetmask(String address) {
    int index = address.indexOf("/");
    String mask = address.substring(index + 1);

    return (index > 0) && isValidIPv4(address.substring(0, index))
        && (isValidIPv4(mask) || isMaskValue(mask, 32));
  }

  public static boolean isValidIPv6WithNetmask(String address) {
    int index = address.indexOf("/");
    String mask = address.substring(index + 1);

    return (index > 0)
        && (isValidIPv6(address.substring(0, index)) && (isValidIPv6(mask) || isMaskValue(
            mask, 128)));
  }

  private static boolean isMaskValue(String component, int size) {
    try {
      int value = Integer.parseInt(component);

      return value >= 0 && value <= size;
    } catch (NumberFormatException e) {
      return false;
    }
  }

  /**
   * Validate the given IPv6 address.
   *
   * @param address
   *          the IP address as a String.
   *
   * @return true if a valid IPv4 address, false otherwise
   */
  public static boolean isValidIPv6(String address) {
    if (address.length() == 0) {
      return false;
    }

    int octet;
    int octets = 0;

    String temp = address + ":";
    boolean doubleColonFound = false;
    int pos;
    int start = 0;
    while (start < temp.length() && (pos = temp.indexOf(':', start)) >= start) {
      if (octets == 8) {
        return false;
      }

      if (start != pos) {
        String value = temp.substring(start, pos);

        if (pos == (temp.length() - 1) && value.indexOf('.') > 0) {
          if (!isValidIPv4(value)) {
            return false;
          }

          octets++; // add an extra one as address covers 2 words.
        } else {
          try {
            octet = Integer.parseInt(temp.substring(start, pos), 16);
          } catch (NumberFormatException ex) {
            return false;
          }
          if (octet < 0 || octet > 0xffff) {
            return false;
          }
        }
      } else {
        if (pos != 1 && pos != temp.length() - 1 && doubleColonFound) {
          return false;
        }
        doubleColonFound = true;
      }
      start = pos + 1;
      octets++;
    }

    return octets == 8 || doubleColonFound;
  }
}