IPv6 validation

Question

I used IPAddressUtil.isIPv6LiteralAddress (ipAddress) method to validate IPv6, but this method fails for ipv6-address/prefix-length format (format is mentioned

Answer 1

My idea is to split it into two part, prefix address and prefix len.

1. validate prefix address use the some regex to validate IPv6 address
2. validate the prefix len that must be an integer
3. prefix address can only have ':' s less than the result ofprefix len divided by 16
4. other logic must be considered as well, leave TODOs here, sorry:(

  private int validateIPv6AddrWithPrefix(String address) {
        int occurCount = 0;
        for(char c : address) {
            if(c=='/'){
                occurCount++;
            }
        }
        if(occurCount != 1){
         //not good, to much / character
            return -1;
        }
        /* 2nd element should be an integer */
        String[] ss = pool.getAddress().split("/");
        Integer prefixLen = null;
        try{
            prefixLen = Integer.valueOf(ss[1]);
                    // TODO validate the prefix range(1, 128)

        }catch(NumberFormatException e) {
            /* not a Integer */
            return -1;
        }
        /* 1st element should be ipv6 address */
        if(!IPaddrUtilities.isIPv6Address(ss[0])) {
            return -1;
        }
        /* validate ':' character logic */
        occurCount = 0;
        for(char c : ss[0].toCharArray()){
            if(c==':') {
                occurCount++;
            }
        }
        if(occurCount >= prefixLen/16) {
            // to much ':' character
            return -1;
        }
        return 0;
    }