codekingpro/portable-devtools

1"""The match_hostname() function from Python 3.5, essential when using SSL."""2 3# Note: This file is under the PSF license as the code comes from the python4# stdlib.   http://docs.python.org/3/license.html5# It is modified to remove commonName support.6 7from __future__ import annotations8 9import ipaddress10import re11import typing12from ipaddress import IPv4Address, IPv6Address13 14if typing.TYPE_CHECKING:15    from .ssl_ import _TYPE_PEER_CERT_RET_DICT16 17__version__ = "3.5.0.1"18 19 20class CertificateError(ValueError):21    pass22 23 24def _dnsname_match(25    dn: typing.Any, hostname: str, max_wildcards: int = 126) -> typing.Match[str] | None | bool:27    """Matching according to RFC 6125, section 6.4.328 29    http://tools.ietf.org/html/rfc6125#section-6.4.330    """31    pats = []32    if not dn:33        return False34 35    # Ported from python3-syntax:36    # leftmost, *remainder = dn.split(r'.')37    parts = dn.split(r".")38    leftmost = parts[0]39    remainder = parts[1:]40 41    wildcards = leftmost.count("*")42    if wildcards > max_wildcards:43        # Issue #17980: avoid denials of service by refusing more44        # than one wildcard per fragment.  A survey of established45        # policy among SSL implementations showed it to be a46        # reasonable choice.47        raise CertificateError(48            "too many wildcards in certificate DNS name: " + repr(dn)49        )50 51    # speed up common case w/o wildcards52    if not wildcards:53        return bool(dn.lower() == hostname.lower())54 55    # RFC 6125, section 6.4.3, subitem 1.56    # The client SHOULD NOT attempt to match a presented identifier in which57    # the wildcard character comprises a label other than the left-most label.58    if leftmost == "*":59        # When '*' is a fragment by itself, it matches a non-empty dotless60        # fragment.61        pats.append("[^.]+")62    elif leftmost.startswith("xn--") or hostname.startswith("xn--"):63        # RFC 6125, section 6.4.3, subitem 3.64        # The client SHOULD NOT attempt to match a presented identifier65        # where the wildcard character is embedded within an A-label or66        # U-label of an internationalized domain name.67        pats.append(re.escape(leftmost))68    else:69        # Otherwise, '*' matches any dotless string, e.g. www*70        pats.append(re.escape(leftmost).replace(r"\*", "[^.]*"))71 72    # add the remaining fragments, ignore any wildcards73    for frag in remainder:74        pats.append(re.escape(frag))75 76    pat = re.compile(r"\A" + r"\.".join(pats) + r"\Z", re.IGNORECASE)77    return pat.match(hostname)78 79 80def _ipaddress_match(ipname: str, host_ip: IPv4Address | IPv6Address) -> bool:81    """Exact matching of IP addresses.82 83    RFC 9110 section 4.3.5: "A reference identity of IP-ID contains the decoded84    bytes of the IP address. An IP version 4 address is 4 octets, and an IP85    version 6 address is 16 octets. [...] A reference identity of type IP-ID86    matches if the address is identical to an iPAddress value of the87    subjectAltName extension of the certificate."88    """89    # OpenSSL may add a trailing newline to a subjectAltName's IP address90    # Divergence from upstream: ipaddress can't handle byte str91    ip = ipaddress.ip_address(ipname.rstrip())92    return bool(ip.packed == host_ip.packed)93 94 95def match_hostname(96    cert: _TYPE_PEER_CERT_RET_DICT | None,97    hostname: str,98    hostname_checks_common_name: bool = False,99) -> None:100    """Verify that *cert* (in decoded format as returned by101    SSLSocket.getpeercert()) matches the *hostname*.  RFC 2818 and RFC 6125102    rules are followed, but IP addresses are not accepted for *hostname*.103 104    CertificateError is raised on failure. On success, the function105    returns nothing.106    """107    if not cert:108        raise ValueError(109            "empty or no certificate, match_hostname needs a "110            "SSL socket or SSL context with either "111            "CERT_OPTIONAL or CERT_REQUIRED"112        )113 114    try:115        host_ip = ipaddress.ip_address(hostname)116    except ValueError:117        # Not an IP address (common case)118        host_ip = None119    dnsnames = []120    san: tuple[tuple[str, str], ...] = cert.get("subjectAltName", ())121    key: str122    value: str123    for key, value in san:124        if key == "DNS":125            if host_ip is None and _dnsname_match(value, hostname):126                return127            dnsnames.append(value)128        elif key == "IP Address":129            if host_ip is not None and _ipaddress_match(value, host_ip):130                return131            dnsnames.append(value)132 133    # We only check 'commonName' if it's enabled and we're not verifying134    # an IP address. IP addresses aren't valid within 'commonName'.135    if hostname_checks_common_name and host_ip is None and not dnsnames:136        for sub in cert.get("subject", ()):137            for key, value in sub:138                if key == "commonName":139                    if _dnsname_match(value, hostname):140                        return141                    dnsnames.append(142                        value143                    )  # Defensive: for older PyPy and OpenSSL versions144 145    if len(dnsnames) > 1:146        raise CertificateError(147            "hostname %r "148            "doesn't match either of %s" % (hostname, ", ".join(map(repr, dnsnames)))149        )150    elif len(dnsnames) == 1:151        raise CertificateError(f"hostname {hostname!r} doesn't match {dnsnames[0]!r}")152    else:153        raise CertificateError("no appropriate subjectAltName fields were found")154