public static boolean isValidIP6Address()

in modules/luni/src/main/java/org/apache/harmony/luni/util/Inet6Util.java [308:448]
113 lines of code
39 McCabe index (conditional complexity)

	public static boolean isValidIP6Address(String ipAddress) {
		int length = ipAddress.length();
		boolean doubleColon = false;
		int numberOfColons = 0;
		int numberOfPeriods = 0;
		int numberOfPercent = 0;
		String word = "";
		char c = 0;
		char prevChar = 0;
		int offset = 0; // offset for [] IP addresses

		if (length < 2) {
            return false;
        }

		for (int i = 0; i < length; i++) {
			prevChar = c;
			c = ipAddress.charAt(i);
			switch (c) {

			// case for an open bracket [x:x:x:...x]
			case '[':
				if (i != 0) {
                    return false; // must be first character
                }
				if (ipAddress.charAt(length - 1) != ']') {
                    return false; // must have a close ]
                }
				offset = 1;
				if (length < 4) {
                    return false;
                }
				break;

			// case for a closed bracket at end of IP [x:x:x:...x]
			case ']':
				if (i != length - 1) {
                    return false; // must be last character
                }
				if (ipAddress.charAt(0) != '[') {
                    return false; // must have a open [
                }
				break;

			// case for the last 32-bits represented as IPv4 x:x:x:x:x:x:d.d.d.d
			case '.':
				numberOfPeriods++;
				if (numberOfPeriods > 3) {
                    return false;
                }
				if (!isValidIP4Word(word)) {
                    return false;
                }
				if (numberOfColons != 6 && !doubleColon) {
                    return false;
                }
				// a special case ::1:2:3:4:5:d.d.d.d allows 7 colons with an
				// IPv4 ending, otherwise 7 :'s is bad
				if (numberOfColons == 7 && ipAddress.charAt(0 + offset) != ':'
						&& ipAddress.charAt(1 + offset) != ':') {
                    return false;
                }
				word = "";
				break;

			case ':':
				numberOfColons++;
				if (numberOfColons > 7) {
                    return false;
                }
				if (numberOfPeriods > 0) {
                    return false;
                }
				if (prevChar == ':') {
					if (doubleColon) {
                        return false;
                    }
					doubleColon = true;
				}
				word = "";
				break;
			case '%':
				if (numberOfColons == 0) {
                    return false;
                }
				numberOfPercent++;

				// validate that the stuff after the % is valid
				if ((i + 1) >= length) {
					// in this case the percent is there but no number is
					// available
					return false;
				}
				try {
					Integer.parseInt(ipAddress.substring(i + 1));
				} catch (NumberFormatException e) {
					// right now we just support an integer after the % so if
					// this is not
					// what is there then return
					return false;
				}
				break;

			default:
				if (numberOfPercent == 0) {
					if (word.length() > 3) {
                        return false;
                    }
					if (!isValidHexChar(c)) {
                        return false;
                    }
				}
				word += c;
			}
		}

		// Check if we have an IPv4 ending
		if (numberOfPeriods > 0) {
			if (numberOfPeriods != 3 || !isValidIP4Word(word)) {
                return false;
            }
		} else {
			// If we're at then end and we haven't had 7 colons then there is a
			// problem unless we encountered a doubleColon
			if (numberOfColons != 7 && !doubleColon) {
				return false;
			}

			// If we have an empty word at the end, it means we ended in either
			// a : or a .
			// If we did not end in :: then this is invalid
			if (numberOfPercent == 0) {
				if (word == "" && ipAddress.charAt(length - 1 - offset) == ':'
						&& ipAddress.charAt(length - 2 - offset) != ':') {
					return false;
				}
			}
		}

		return true;
	}