url.py

from __future__ import absolute_import
import re
from collections import namedtuple

from ..exceptions import LocationParseError
from ..packages import six


url_attrs = ["scheme", "auth", "host", "port", "path", "query", "fragment"]

# We only want to normalize urls with an HTTP(S) scheme.
# urllib3 infers URLs without a scheme (None) to be http.
NORMALIZABLE_SCHEMES = ("http", "https", None)

# Almost all of these patterns were derived from the
# 'rfc3986' module: https://github.com/python-hyper/rfc3986
PERCENT_RE = re.compile(r"%[a-fA-F0-9]{2}")
SCHEME_RE = re.compile(r"^(?:[a-zA-Z][a-zA-Z0-9+-]*:|/)")
URI_RE = re.compile(
    r"^(?:([a-zA-Z][a-zA-Z0-9+.-]*):)?"
    r"(?://([^\\/?#]*))?"
    r"([^?#]*)"
    r"(?:\?([^#]*))?"
    r"(?:#(.*))?$",
    re.UNICODE | re.DOTALL,
)

IPV4_PAT = r"(?:[0-9]{1,3}\.){3}[0-9]{1,3}"
HEX_PAT = "[0-9A-Fa-f]{1,4}"
LS32_PAT = "(?:{hex}:{hex}|{ipv4})".format(hex=HEX_PAT, ipv4=IPV4_PAT)
_subs = {"hex": HEX_PAT, "ls32": LS32_PAT}
_variations = [
    #                            6( h16 ":" ) ls32
    "(?:%(hex)s:){6}%(ls32)s",
    #                       "::" 5( h16 ":" ) ls32
    "::(?:%(hex)s:){5}%(ls32)s",
    # [               h16 ] "::" 4( h16 ":" ) ls32
    "(?:%(hex)s)?::(?:%(hex)s:){4}%(ls32)s",
    # [ *1( h16 ":" ) h16 ] "::" 3( h16 ":" ) ls32
    "(?:(?:%(hex)s:)?%(hex)s)?::(?:%(hex)s:){3}%(ls32)s",
    # [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32
    "(?:(?:%(hex)s:){0,2}%(hex)s)?::(?:%(hex)s:){2}%(ls32)s",
    # [ *3( h16 ":" ) h16 ] "::"    h16 ":"   ls32
    "(?:(?:%(hex)s:){0,3}%(hex)s)?::%(hex)s:%(ls32)s",
    # [ *4( h16 ":" ) h16 ] "::"              ls32
    "(?:(?:%(hex)s:){0,4}%(hex)s)?::%(ls32)s",
    # [ *5( h16 ":" ) h16 ] "::"              h16
    "(?:(?:%(hex)s:){0,5}%(hex)s)?::%(hex)s",
    # [ *6( h16 ":" ) h16 ] "::"
    "(?:(?:%(hex)s:){0,6}%(hex)s)?::",
]

UNRESERVED_PAT = r"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789._!\-~"
IPV6_PAT = "(?:" + "|".join([x % _subs for x in _variations]) + ")"
ZONE_ID_PAT = "(?:%25|%)(?:[" + UNRESERVED_PAT + "]|%[a-fA-F0-9]{2})+"
IPV6_ADDRZ_PAT = r"\[" + IPV6_PAT + r"(?:" + ZONE_ID_PAT + r")?\]"
REG_NAME_PAT = r"(?:[^\[\]%:/?#]|%[a-fA-F0-9]{2})*"
TARGET_RE = re.compile(r"^(/[^?#]*)(?:\?([^#]*))?(?:#.*)?$")

IPV4_RE = re.compile("^" + IPV4_PAT + "$")
IPV6_RE = re.compile("^" + IPV6_PAT + "$")
IPV6_ADDRZ_RE = re.compile("^" + IPV6_ADDRZ_PAT + "$")
BRACELESS_IPV6_ADDRZ_RE = re.compile("^" + IPV6_ADDRZ_PAT[2:-2] + "$")
ZONE_ID_RE = re.compile("(" + ZONE_ID_PAT + r")\]$")

SUBAUTHORITY_PAT = (u"^(?:(.*)@)?(%s|%s|%s)(?::([0-9]{0,5}))?$") % (
    REG_NAME_PAT,
    IPV4_PAT,
    IPV6_ADDRZ_PAT,
)
SUBAUTHORITY_RE = re.compile(SUBAUTHORITY_PAT, re.UNICODE | re.DOTALL)

UNRESERVED_CHARS = set(
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789._-~"
)
SUB_DELIM_CHARS = set("!$&'()*+,;=")
USERINFO_CHARS = UNRESERVED_CHARS | SUB_DELIM_CHARS | {":"}
PATH_CHARS = USERINFO_CHARS | {"@", "/"}
QUERY_CHARS = FRAGMENT_CHARS = PATH_CHARS | {"?"}


class Url(namedtuple("Url", url_attrs)):
    """
    Data structure for representing an HTTP URL. Used as a return value for
    :func:`parse_url`. Both the scheme and host are normalized as they are
    both case-insensitive according to RFC 3986.
    """

    __slots__ = ()

    def __new__(
        cls,
        scheme=None,
        auth=None,
        host=None,
        port=None,
        path=None,
        query=None,
        fragment=None,
    ):
        if path and not path.startswith("/"):
            path = "/" + path
        if scheme is not None:
            scheme = scheme.lower()
        return super(Url, cls).__new__(
            cls, scheme, auth, host, port, path, query, fragment
        )

    @property
    def hostname(self):
        """For backwards-compatibility with urlparse. We're nice like that."""
        return self.host

    @property
    def request_uri(self):
        """Absolute path including the query string."""
        uri = self.path or "/"

        if self.query is not None:
            uri += "?" + self.query

        return uri

    @property
    def netloc(self):
        """Network location including host and port"""
        if self.port:
            return "%s:%d" % (self.host, self.port)
        return self.host

    @property
    def url(self):
        """
        Convert self into a url

        This function should more or less round-trip with :func:`.parse_url`. The
        returned url may not be exactly the same as the url inputted to
        :func:`.parse_url`, but it should be equivalent by the RFC (e.g., urls
        with a blank port will have : removed).

        Example: ::

            >>> U = parse_url('http://google.com/mail/')
            >>> U.url
            'http://google.com/mail/'
            >>> Url('http', 'username:password', 'host.com', 80,
            ... '/path', 'query', 'fragment').url
            'http://username:[email protected]:80/path?query#fragment'
        """
        scheme, auth, host, port, path, query, fragment = self
        url = u""

        # We use "is not None" we want things to happen with empty strings (or 0 port)
        if scheme is not None:
            url += scheme + u"://"
        if auth is not None:
            url += auth + u"@"
        if host is not None:
            url += host
        if port is not None:
            url += u":" + str(port)
        if path is not None:
            url += path
        if query is not None:
            url += u"?" + query
        if fragment is not None:
            url += u"#" + fragment

        return url

    def __str__(self):
        return self.url


def split_first(s, delims):
    """
    .. deprecated:: 1.25

    Given a string and an iterable of delimiters, split on the first found
    delimiter. Return two split parts and the matched delimiter.

    If not found, then the first part is the full input string.

    Example::

        >>> split_first('foo/bar?baz', '?/=')
        ('foo', 'bar?baz', '/')
        >>> split_first('foo/bar?baz', '123')
        ('foo/bar?baz', '', None)

    Scales linearly with number of delims. Not ideal for large number of delims.
    """
    min_idx = None
    min_delim = None
    for d in delims:
        idx = s.find(d)
        if idx < 0:
            continue

        if min_idx is None or idx < min_idx:
            min_idx = idx
            min_delim = d

    if min_idx is None or min_idx < 0:
        return s, "", None

    return s[:min_idx], s[min_idx + 1 :], min_delim


def _encode_invalid_chars(component, allowed_chars, encoding="utf-8"):
    """Percent-encodes a URI component without reapplying
    onto an already percent-encoded component.
    """
    if component is None:
        return component

    component = six.ensure_text(component)

    # Normalize existing percent-encoded bytes.
    # Try to see if the component we're encoding is already percent-encoded
    # so we can skip all '%' characters but still encode all others.
    component, percent_encodings = PERCENT_RE.subn(
        lambda match: match.group(0).upper(), component
    )

    uri_bytes = component.encode("utf-8", "surrogatepass")
    is_percent_encoded = percent_encodings == uri_bytes.count(b"%")
    encoded_component = bytearray()

    for i in range(0, len(uri_bytes)):
        # Will return a single character bytestring on both Python 2 & 3
        byte = uri_bytes[i : i + 1]
        byte_ord = ord(byte)
        if (is_percent_encoded and byte == b"%") or (
            byte_ord < 128 and byte.decode() in allowed_chars
        ):
            encoded_component += byte
            continue
        encoded_component.extend(b"%" + (hex(byte_ord)[2:].encode().zfill(2).upper()))

    return encoded_component.decode(encoding)


def _remove_path_dot_segments(path):
    # See http://tools.ietf.org/html/rfc3986#section-5.2.4 for pseudo-code
    segments = path.split("/")  # Turn the path into a list of segments
    output = []  # Initialize the variable to use to store output

    for segment in segments:
        # '.' is the current directory, so ignore it, it is superfluous
        if segment == ".":
            continue
        # Anything other than '..', should be appended to the output
        elif segment != "..":
            output.append(segment)
        # In this case segment == '..', if we can, we should pop the last
        # element
        elif output:
            output.pop()

    # If the path starts with '/' and the output is empty or the first string
    # is non-empty
    if path.startswith("/") and (not output or output[0]):
        output.insert(0, "")

    # If the path starts with '/.' or '/..' ensure we add one more empty
    # string to add a trailing '/'
    if path.endswith(("/.", "/..")):
        output.append("")

    return "/".join(output)


def _normalize_host(host, scheme):
    if host:
        if isinstance(host, six.binary_type):
            host = six.ensure_str(host)

        if scheme in NORMALIZABLE_SCHEMES:
            is_ipv6 = IPV6_ADDRZ_RE.match(host)
            if is_ipv6:
                match = ZONE_ID_RE.search(host)
                if match:
                    start, end = match.span(1)
                    zone_id = host[start:end]

                    if zone_id.startswith("%25") and zone_id != "%25":
                        zone_id = zone_id[3:]
                    else:
                        zone_id = zone_id[1:]
                    zone_id = "%" + _encode_invalid_chars(zone_id, UNRESERVED_CHARS)
                    return host[:start].lower() + zone_id + host[end:]
                else:
                    return host.lower()
            elif not IPV4_RE.match(host):
                return six.ensure_str(
                    b".".join([_idna_encode(label) for label in host.split(".")])
                )
    return host


def _idna_encode(name):
    if name and any([ord(x) > 128 for x in name]):
        try:
            import idna
        except ImportError:
            six.raise_from(
                LocationParseError("Unable to parse URL without the 'idna' module"),
                None,
            )
        try:
            return idna.encode(name.lower(), strict=True, std3_rules=True)
        except idna.IDNAError:
            six.raise_from(
                LocationParseError(u"Name '%s' is not a valid IDNA label" % name), None
            )
    return name.lower().encode("ascii")


def _encode_target(target):
    """Percent-encodes a request target so that there are no invalid characters"""
    path, query = TARGET_RE.match(target).groups()
    target = _encode_invalid_chars(path, PATH_CHARS)
    query = _encode_invalid_chars(query, QUERY_CHARS)
    if query is not None:
        target += "?" + query
    return target


def parse_url(url):
    """
    Given a url, return a parsed :class:`.Url` namedtuple. Best-effort is
    performed to parse incomplete urls. Fields not provided will be None.
    This parser is RFC 3986 compliant.

    The parser logic and helper functions are based heavily on
    work done in the ``rfc3986`` module.

    :param str url: URL to parse into a :class:`.Url` namedtuple.

    Partly backwards-compatible with :mod:`urlparse`.

    Example::

        >>> parse_url('http://google.com/mail/')
        Url(scheme='http', host='google.com', port=None, path='/mail/', ...)
        >>> parse_url('google.com:80')
        Url(scheme=None, host='google.com', port=80, path=None, ...)
        >>> parse_url('/foo?bar')
        Url(scheme=None, host=None, port=None, path='/foo', query='bar', ...)
    """
    if not url:
        # Empty
        return Url()

    source_url = url
    if not SCHEME_RE.search(url):
        url = "//" + url

    try:
        scheme, authority, path, query, fragment = URI_RE.match(url).groups()
        normalize_uri = scheme is None or scheme.lower() in NORMALIZABLE_SCHEMES

        if scheme:
            scheme = scheme.lower()

        if authority:
            auth, host, port = SUBAUTHORITY_RE.match(authority).groups()
            if auth and normalize_uri:
                auth = _encode_invalid_chars(auth, USERINFO_CHARS)
            if port == "":
                port = None
        else:
            auth, host, port = None, None, None

        if port is not None:
            port = int(port)
            if not (0 <= port <= 65535):
                raise LocationParseError(url)

        host = _normalize_host(host, scheme)

        if normalize_uri and path:
            path = _remove_path_dot_segments(path)
            path = _encode_invalid_chars(path, PATH_CHARS)
        if normalize_uri and query:
            query = _encode_invalid_chars(query, QUERY_CHARS)
        if normalize_uri and fragment:
            fragment = _encode_invalid_chars(fragment, FRAGMENT_CHARS)

    except (ValueError, AttributeError):
        return six.raise_from(LocationParseError(source_url), None)

    # For the sake of backwards compatibility we put empty
    # string values for path if there are any defined values
    # beyond the path in the URL.
    # TODO: Remove this when we break backwards compatibility.
    if not path:
        if query is not None or fragment is not None:
            path = ""
        else:
            path = None

    # Ensure that each part of the URL is a `str` for
    # backwards compatibility.
    if isinstance(url, six.text_type):
        ensure_func = six.ensure_text
    else:
        ensure_func = six.ensure_str

    def ensure_type(x):
        return x if x is None else ensure_func(x)

    return Url(
        scheme=ensure_type(scheme),
        auth=ensure_type(auth),
        host=ensure_type(host),
        port=port,
        path=ensure_type(path),
        query=ensure_type(query),
        fragment=ensure_type(fragment),
    )


def get_host(url):
    """
    Deprecated. Use :func:`parse_url` instead.
    """
    p = parse_url(url)
    return p.scheme or "http", p.hostname, p.port