Method isValidHost

lib/java/net/URI.java:569–611

distinguish between IPv4, IPv6, domain name and validate it based on its type

(boolean forceServer, String host)

         * its type
         */
        private boolean isValidHost(boolean forceServer, String host)
                throws URISyntaxException {
            if (host.charAt(0) == '[') {
                // ipv6 address
                if (host.charAt(host.length() - 1) != ']') {
                    throw new URISyntaxException(host,
                            Messages.getString("luni.8D"), 0); //$NON-NLS-1$
                }
                if (!isValidIP6Address(host)) {
                    throw new URISyntaxException(host, Messages.getString("luni.8E")); //$NON-NLS-1$
                }
                return true;
            }

            // '[' and ']' can only be the first char and last char
            // of the host name
            if (host.indexOf('[') != -1 || host.indexOf(']') != -1) {
                throw new URISyntaxException(host, Messages.getString("luni.8F"), 0); //$NON-NLS-1$
            }

            int index = host.lastIndexOf('.');
            if (index < 0 || index == host.length() - 1
                    || !Character.isDigit(host.charAt(index + 1))) {
                // domain name
                if (isValidDomainName(host)) {
                    return true;
                }
                if (forceServer) {
                    throw new URISyntaxException(host,
                            Messages.getString("luni.8F"), 0); //$NON-NLS-1$
                }
                return false;
            }

            // IPv4 address
            if (isValidIPv4Address(host)) {
                return true;
            }
            if (forceServer) {
                throw new URISyntaxException(host, Messages.getString("luni.90"), 0); //$NON-NLS-1$
            }
            return false;
        }

        private boolean isValidDomainName(String host) {
            try {