Function for check if input is an ipv4 address.

check_if_ipv4.py

# regex to match ipv4
# (?:[0-9]{1,3}\.){3}[0-9]{1,3}

# v1
def check_if_ipv4(ip):
	quad = ip.split(".")
	quadinteger = []
	try:
		quadinteger = [int(num) for num in quad]
	except ValueError:
		#print('ERROR: Must be an ipv4 address')
		return
	while len(quadinteger) != 4:
		#print('ERROR: Must be four octects')
		return
	for octect in quadinteger:
		if octect > 255 or octect < 0:
			#print('ERROR: Each octects must be beetween 0 and 255')
			return
	return ip

# v2
import re

ip_pattern = re.compile(r'(?:(?:25[0-5]|2[0-4][0-9]|1?[0-9]?[0-9])\.){3}'
                            r'(?:25[0-5]|2[0-4][0-9]|1?[0-9]?[0-9])')

def validate_ip(s):
    if ip_pattern.match(s):
        return True
    return False

assert validate_ip(ip), 'Invalid IP Address'