protected boolean isValidAuthority()

in src/main/java/org/apache/commons/validator/UrlValidator.java [293:372]
60 lines of code
18 McCabe index (conditional complexity)

    protected boolean isValidAuthority(final String authority) {
        if (authority == null) {
            return false;
        }

        final InetAddressValidator inetAddressValidator =
                InetAddressValidator.getInstance();

        final Matcher authorityMatcher = AUTHORITY_PATTERN.matcher(authority);
        if (!authorityMatcher.matches()) {
            return false;
        }

        boolean hostname = false;
        // check if authority is IP address or hostname
        String hostIP = authorityMatcher.group(PARSE_AUTHORITY_HOST_IP);
        final boolean ipV4Address = inetAddressValidator.isValid(hostIP);

        if (!ipV4Address) {
            // Domain is hostname name
            hostname = DOMAIN_PATTERN.matcher(hostIP).matches();
        }

        //rightmost hostname will never start with a digit.
        if (hostname) {
            // LOW-TECH FIX FOR VALIDATOR-202
            // TODO: Rewrite to use ArrayList and .add semantics: see VALIDATOR-203
            final char[] chars = hostIP.toCharArray();
            int size = 1;
            for (final char element : chars) {
                if (element == '.') {
                    size++;
                }
            }
            final String[] domainSegment = new String[size];
            boolean match = true;
            int segmentCount = 0;
            int segmentLength = 0;

            while (match) {
                final Matcher atomMatcher = ATOM_PATTERN.matcher(hostIP);
                match = atomMatcher.matches();
                if (match) {
                    domainSegment[segmentCount] = atomMatcher.group(1);
                    segmentLength = domainSegment[segmentCount].length() + 1;
                    hostIP =
                            segmentLength >= hostIP.length()
                            ? ""
                            : hostIP.substring(segmentLength);

                    segmentCount++;
                }
            }
            final String topLevel = domainSegment[segmentCount - 1];


            // First letter of top level must be an alpha
            // Make sure there's a host name preceding the authority.
            if (topLevel.length() < TOP_LEVEL_MIN_LEN || topLevel.length() > TOP_LEVEL_MAX_LEN || !ALPHA_PATTERN.matcher(topLevel.substring(0, 1)).matches()
                    || segmentCount < 2) {
                return false;
            }
        }

        if (!hostname && !ipV4Address) {
            return false;
        }

        final String port = authorityMatcher.group(PARSE_AUTHORITY_PORT);
        if (port != null && !PORT_PATTERN.matcher(port).matches()) {
            return false;
        }

        final String extra = authorityMatcher.group(PARSE_AUTHORITY_EXTRA);
        if (!GenericValidator.isBlankOrNull(extra)) {
            return false;
        }

        return true;
    }