def _dnsname_match(dn, hostname, max_wildcards=1):
    """Matching according to RFC 6125, section 6.4.3

    http://tools.ietf.org/html/rfc6125#section-6.4.3
    """
    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

    http://tools.ietf.org/html/rfc6125#section-6.4.3
    
product/gradle-plugin/src/main/python/pip/_vendor/urllib3/packages/ssl_match_hostname/_implementation.py