regexes/url.py

import re

URL_REGEX = re.compile(
    r"(?:^|(?<![\w\/\.]))"
    # protocol identifier
    # r"(?:(?:https?|ftp)://)"  <-- alt?
    r"(?:(?:https?:\/\/|ftp:\/\/|www\d{0,3}\.))"
    # user:pass authentication
    r"(?:\S+(?::\S*)?@)?" r"(?:"
    # IP address exclusion
    # private & local networks
    r"(?!(?:10|127)(?:\.\d{1,3}){3})"
    r"(?!(?:169\.254|192\.168)(?:\.\d{1,3}){2})"
    r"(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})"
    # IP address dotted notation octets
    # excludes loopback network 0.0.0.0
    # excludes reserved space >= 224.0.0.0
    # excludes network & broadcast addresses
    # (first & last IP address of each class)
    r"(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])"
    r"(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}"
    r"(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))"
    r"|"
    # host name
    r"(?:(?:[a-z\\u00a1-\\uffff0-9]-?)*[a-z\\u00a1-\\uffff0-9]+)"
    # domain name
    r"(?:\.(?:[a-z\\u00a1-\\uffff0-9]-?)*[a-z\\u00a1-\\uffff0-9]+)*"
    # TLD identifier
    r"(?:\.(?:[a-z\\u00a1-\\uffff]{2,}))" r"|" r"(?:(localhost))" r")"
    # port number
    r"(?::\d{2,5})?"
    # resource path
    r"(?:\/[^\)\]\}\s]*)?",
    # r"(?:$|(?![\w?!+&\/\)]))",
    # @jfilter: I removed the line above from the regex because I don't understand what it is used for, maybe it was useful?
    # But I made sure that it does not include ), ] and } in the URL.
    flags=re.UNICODE | re.IGNORECASE,
)