Validate Ip Address

To solve this coding challenge, we need to determine whether a given string

queryIP

represents a valid IPv4 or IPv6 address, or whether it is not a valid IP address of either type. Below, you'll find a step-by-step explanation of how to approach this problem, followed by pseudocode with comments to guide the implementation.

# Explanation

1. Problem Understanding :
• We are given a string
  queryIP
  and need to categorize it as either "IPv4", "IPv6", or "Neither".
• An IPv4 address consists of four decimal numbers separated by dots. Each of these numbers (called "octets") ranges from 0 to 255, and must not have leading zeros.
• An IPv6 address consists of eight groups of four hexadecimal digits separated by colons. Each group (called "hextet") can contain digits from 0-9 and letters from a-f (either upper or lower case). Leading zeros are allowed but empty groups are not.
2. Solution Outline :
• First, check whether the given IP address contains either a dot (
  .
  ) or a colon (
  :
  ) to determine whether it is an IPv4 or IPv6 address.
• For IPv4:
• Split the address by dots.
• Verify that there are exactly four parts.
• Ensure each part is a valid decimal number without leading zeros, and within the range [0, 255].
• For IPv6:
• Split the address by colons.
• Verify that there are exactly eight parts.
• Ensure each part is a valid hexadecimal number, with a length between 1 and 4 characters.
• If neither condition satisfies, return "Neither".

Detailed Steps in Pseudocode

3. Initial Check :
• Check if the string contains a dot
  .
  :
• If true, check for IPv4 validity.
• Check if the string contains a colon
  :
  :
• If true, check for IPv6 validity.
• If neither, return "Neither".
4. IPv4 Validity Check :
• Split the string by
  .
  into parts.
• Verify that there are exactly 4 parts.
• For each part:
• Check if it consists only of digits.
• Convert it to an integer and check if it is within the range [0, 255].
• Ensure it does not have leading zeros.
• If all parts satisfy the conditions, return "IPv4".
5. IPv6 Validity Check :
• Split the string by
  :
  into parts.
• Verify that there are exactly 8 parts.
• For each part:
• Check if it consists only of valid hexadecimal digits (0-9, a-f, A-F).
• Ensure the length is between 1 and 4 characters.
• If all parts satisfy the conditions, return "IPv6".
6. Return Neither :
• If none of the above conditions are satisfied, return "Neither".

Pseudocode #1

                                            
# Function to determine the type of IP address
Function validIPAddress(queryIP):
    # Check if the IP is in IPv4 format by looking for a dot '.'
    If '.' in queryIP:
        # Split the string by dots
        parts = queryIP.split('.')
        
        # IPv4 addresses must have exactly 4 parts
        If length of parts is not 4:
            Return "Neither"
        
        # Check each part of the IPv4 address
        For part in parts:
            # Each part must be composed solely of digits
            If not part.isdigit():
                Return "Neither"
            
            # Convert the part to an integer
            intPart = integer(part)
            
            # Validate the range [0, 255]
            If intPart is not in the range 0 to 255:
                Return "Neither"
            
            # Check for leading zeros
            If length of part > 1 and part[0] is '0':
                Return "Neither"
        
        # If all checks pass, it is a valid IPv4 address
        Return "IPv4"
    
    # Check if the IP is in IPv6 format by looking for a colon ':'
    If ':' in queryIP:
        # Split the string by colons
        parts = queryIP.split(':')
        
        # IPv6 addresses must have exactly 8 parts
        If length of parts is not 8:
            Return "Neither"
        
        # Check each part of the IPv6 address
        For part in parts:
            # Each part must be 1-4 characters long and composed of valid hex digits
            If length of part is not in the range 1 to 4 or not isHexadecimal(part):
                Return "Neither"
        
        # If all checks pass, it is a valid IPv6 address
        Return "IPv6"
    
    # If neither format is detected, return "Neither"
    Return "Neither"

                                        

Pseudocode #2: Helper Functions

                                            
# Helper function to check if a string is a valid hexadecimal number
Function isHexadecimal(string):
    validChars = "0123456789abcdefABCDEF"
    
    # Iterate over each character in the string
    For char in string:
        # Each character must be a valid hexadecimal digit
        If char not in validChars:
            Return False
    
    # If all characters are valid, return True
    Return True

                                        

# Conclusion

In conclusion, the pseudocode provides a robust method to validate whether a given IP address conforms to either IPv4 or IPv6 standards, or if it does not fit into either category, returning "Neither." Each step of the validation process checks strict conditions to ensure accuracy, including splitting the input on appropriate delimiters, checking the count and format of each segment, and validating numerical and hexadecimal ranges.