Method parseSubnet0

core/src/main/java/io/questdb/std/Numbers.java:2103–2173

(CharSequence sequence, final int p, int lim, int netmaskLength)

    // test whether the subnet matches the netmaskLength (according to postgres rules)
    // throws NumericException if sequence is not a valid subnet OR the subnet doesn't match the netmaskLength
    public static int parseSubnet0(CharSequence sequence, final int p, int lim, int netmaskLength) throws NumericException {
        int hi;
        int lo = p;
        int num;
        int ipv4 = 0;
        int count = 0;
        int checker = 0xffffffff;
        int bits = 32 - netmaskLength;
        int i = 1;

        if (lim == 0) {
            throw NumericException.instance().put("empty IPv4 subnet string");
        }

        final char sign = sequence.charAt(0);

        if (notDigit(sign)) {
            throw NumericException.instance().put("invalid IPv4 subnet format: ").put(sequence);
        }

        while ((hi = Chars.indexOf(sequence, lo, '.')) > -1) {
            num = parseInt(sequence, lo, hi);

            if (num > 255) {
                throw NumericException.instance().put("IPv4 octet out of range [0-255]: ").put(num);
            }
            // each byte goes to left-most pos in int - accounts for issues that arise from parsing variable length subnets
            ipv4 = ipv4 | (num << ((4 - i) * 8));
            count++;
            i++;
            lo = hi + 1;
        }

        if (count > 3) {
            throw NumericException.instance().put("too many octets in IPv4 subnet: ").put(sequence);
        }

        num = parseInt(sequence, lo, lim);

        if (num > 255) {
            throw NumericException.instance().put("IPv4 octet out of range [0-255]: ").put(num);
        }

        //if netmaskLength is full byte longer than subnet
        if (count == 0) {
            if (netmaskLength >= 16) {
                throw NumericException.instance().put("netmask length too long for single octet subnet: ").put(netmaskLength);
            }
            checker = (checker << bits);
            num = (num << 24) & checker;
            return num;
        }
        //if netmaskLength is a full byte longer than subnet
        else if (count == 1 && netmaskLength >= 24) {
            throw NumericException.instance().put("netmask length too long for two octet subnet: ").put(netmaskLength);
        }
        //if netmaskLength is a full byte longer than subnet
        else if (count == 2 && netmaskLength >= 32) {