def _dnsname_match(dn, hostname, max_wildcards=1):
        pats = []
        if not dn:
            return False

        # Ported from python3-syntax:
        # leftmost, *remainder = dn.split(r'.')
        parts = dn.split(r'.')
        leftmost = parts[0]
        remainder = parts[1:]

        wildcards = leftmost.count('*')
        if wildcards > max_wildcards:
            # Issue #17980: avoid denials of service by refusing more
            # than one wildcard per fragment.  A survey of established
            # policy among SSL implementations showed it to be a
            # reasonable choice.
            raise CertificateError(
                "too many wildcards in certificate DNS name: " + repr(dn))

        # speed up common case w/o wildcards
        if not wildcards:
            return dn.lower() == hostname.lower()

        # RFC 6125, section 6.4.3, subitem 1.
        # The client SHOULD NOT attempt to match a presented identifier in which
        # the wildcard character comprises a label other than the left-most label.
        if leftmost == '*':
            # When '*' is a fragment by itself, it matches a non-empty dotless
            # fragment.
            pats.append('[^.]+')
        elif leftmost.startswith('xn--') or hostname.startswith('xn--'):
            # RFC 6125, section 6.4.3, subitem 3.
            # The client SHOULD NOT attempt to match a presented identifier
            # where the wildcard character is embedded within an A-label or
            # U-label of an internationalized domain name.
            pats.append(re.escape(leftmost))
        else:
            # Otherwise, '*' matches any dotless string, e.g. www*
            pats.append(re.escape(leftmost).replace(r'\*', '[^.]*'))

        # add the remaining fragments, ignore any wildcards
        for frag in remainder:
            pats.append(re.escape(frag))

        pat = re.compile(r'\A' + r'\.'.join(pats) + r'\Z', re.IGNORECASE)
        return pat.match(hostname)
Matching according to RFC 6125, section 6.4.3
dataset/ETHPy150Open GeekTrainer/Flask/Work/Trivia - Module 5/env/Lib/site-packages/setuptools/ssl_support.py/_dnsname_match