auth.py

"""
requests.auth
~~~~~~~~~~~~~

This module contains the authentication handlers for Requests.
"""

import hashlib
import os
import re
import threading
import time
import warnings
from base64 import b64encode

from ._internal_utils import to_native_string
from .compat import basestring, str, urlparse
from .cookies import extract_cookies_to_jar
from .utils import parse_dict_header

CONTENT_TYPE_FORM_URLENCODED = "application/x-www-form-urlencoded"
CONTENT_TYPE_MULTI_PART = "multipart/form-data"


def _basic_auth_str(username, password):
    """Returns a Basic Auth string."""

    # "I want us to put a big-ol' comment on top of it that
    # says that this behaviour is dumb but we need to preserve
    # it because people are relying on it."
    #    - Lukasa
    #
    # These are here solely to maintain backwards compatibility
    # for things like ints. This will be removed in 3.0.0.
    if not isinstance(username, basestring):
        warnings.warn(
            "Non-string usernames will no longer be supported in Requests "
            "3.0.0. Please convert the object you've passed in ({!r}) to "
            "a string or bytes object in the near future to avoid "
            "problems.".format(username),
            category=DeprecationWarning,
        )
        username = str(username)

    if not isinstance(password, basestring):
        warnings.warn(
            "Non-string passwords will no longer be supported in Requests "
            "3.0.0. Please convert the object you've passed in ({!r}) to "
            "a string or bytes object in the near future to avoid "
            "problems.".format(type(password)),
            category=DeprecationWarning,
        )
        password = str(password)
    # -- End Removal --

    if isinstance(username, str):
        username = username.encode("latin1")

    if isinstance(password, str):
        password = password.encode("latin1")

    authstr = "Basic " + to_native_string(
        b64encode(b":".join((username, password))).strip()
    )

    return authstr


class AuthBase:
    """Base class that all auth implementations derive from"""

    def __call__(self, r):
        raise NotImplementedError("Auth hooks must be callable.")


class HTTPBasicAuth(AuthBase):
    """Attaches HTTP Basic Authentication to the given Request object."""

    def __init__(self, username, password):
        self.username = username
        self.password = password

    def __eq__(self, other):
        return all(
            [
                self.username == getattr(other, "username", None),
                self.password == getattr(other, "password", None),
            ]
        )

    def __ne__(self, other):
        return not self == other

    def __call__(self, r):
        r.headers["Authorization"] = _basic_auth_str(self.username, self.password)
        return r


class HTTPProxyAuth(HTTPBasicAuth):
    """Attaches HTTP Proxy Authentication to a given Request object."""

    def __call__(self, r):
        r.headers["Proxy-Authorization"] = _basic_auth_str(self.username, self.password)
        return r


class HTTPDigestAuth(AuthBase):
    """Attaches HTTP Digest Authentication to the given Request object."""

    def __init__(self, username, password):
        self.username = username
        self.password = password
        # Keep state in per-thread local storage
        self._thread_local = threading.local()

    def init_per_thread_state(self):
        # Ensure state is initialized just once per-thread
        if not hasattr(self._thread_local, "init"):
            self._thread_local.init = True
            self._thread_local.last_nonce = ""
            self._thread_local.nonce_count = 0
            self._thread_local.chal = {}
            self._thread_local.pos = None
            self._thread_local.num_401_calls = None

    def build_digest_header(self, method, url):
        """
        :rtype: str
        """

        realm = self._thread_local.chal["realm"]
        nonce = self._thread_local.chal["nonce"]
        qop = self._thread_local.chal.get("qop")
        algorithm = self._thread_local.chal.get("algorithm")
        opaque = self._thread_local.chal.get("opaque")
        hash_utf8 = None

        if algorithm is None:
            _algorithm = "MD5"
        else:
            _algorithm = algorithm.upper()
        # lambdas assume digest modules are imported at the top level
        if _algorithm == "MD5" or _algorithm == "MD5-SESS":

            def md5_utf8(x):
                if isinstance(x, str):
                    x = x.encode("utf-8")
                return hashlib.md5(x).hexdigest()

            hash_utf8 = md5_utf8
        elif _algorithm == "SHA":

            def sha_utf8(x):
                if isinstance(x, str):
                    x = x.encode("utf-8")
                return hashlib.sha1(x).hexdigest()

            hash_utf8 = sha_utf8
        elif _algorithm == "SHA-256":

            def sha256_utf8(x):
                if isinstance(x, str):
                    x = x.encode("utf-8")
                return hashlib.sha256(x).hexdigest()

            hash_utf8 = sha256_utf8
        elif _algorithm == "SHA-512":

            def sha512_utf8(x):
                if isinstance(x, str):
                    x = x.encode("utf-8")
                return hashlib.sha512(x).hexdigest()

            hash_utf8 = sha512_utf8

        KD = lambda s, d: hash_utf8(f"{s}:{d}")  # noqa:E731

        if hash_utf8 is None:
            return None

        # XXX not implemented yet
        entdig = None
        p_parsed = urlparse(url)
        #: path is request-uri defined in RFC 2616 which should not be empty
        path = p_parsed.path or "/"
        if p_parsed.query:
            path += f"?{p_parsed.query}"

        A1 = f"{self.username}:{realm}:{self.password}"
        A2 = f"{method}:{path}"

        HA1 = hash_utf8(A1)
        HA2 = hash_utf8(A2)

        if nonce == self._thread_local.last_nonce:
            self._thread_local.nonce_count += 1
        else:
            self._thread_local.nonce_count = 1
        ncvalue = f"{self._thread_local.nonce_count:08x}"
        s = str(self._thread_local.nonce_count).encode("utf-8")
        s += nonce.encode("utf-8")
        s += time.ctime().encode("utf-8")
        s += os.urandom(8)

        cnonce = hashlib.sha1(s).hexdigest()[:16]
        if _algorithm == "MD5-SESS":
            HA1 = hash_utf8(f"{HA1}:{nonce}:{cnonce}")

        if not qop:
            respdig = KD(HA1, f"{nonce}:{HA2}")
        elif qop == "auth" or "auth" in qop.split(","):
            noncebit = f"{nonce}:{ncvalue}:{cnonce}:auth:{HA2}"
            respdig = KD(HA1, noncebit)
        else:
            # XXX handle auth-int.
            return None

        self._thread_local.last_nonce = nonce

        # XXX should the partial digests be encoded too?
        base = (
            f'username="{self.username}", realm="{realm}", nonce="{nonce}", '
            f'uri="{path}", response="{respdig}"'
        )
        if opaque:
            base += f', opaque="{opaque}"'
        if algorithm:
            base += f', algorithm="{algorithm}"'
        if entdig:
            base += f', digest="{entdig}"'
        if qop:
            base += f', qop="auth", nc={ncvalue}, cnonce="{cnonce}"'

        return f"Digest {base}"

    def handle_redirect(self, r, **kwargs):
        """Reset num_401_calls counter on redirects."""
        if r.is_redirect:
            self._thread_local.num_401_calls = 1

    def handle_401(self, r, **kwargs):
        """
        Takes the given response and tries digest-auth, if needed.

        :rtype: requests.Response
        """

        # If response is not 4xx, do not auth
        # See https://github.com/psf/requests/issues/3772
        if not 400 <= r.status_code < 500:
            self._thread_local.num_401_calls = 1
            return r

        if self._thread_local.pos is not None:
            # Rewind the file position indicator of the body to where
            # it was to resend the request.
            r.request.body.seek(self._thread_local.pos)
        s_auth = r.headers.get("www-authenticate", "")

        if "digest" in s_auth.lower() and self._thread_local.num_401_calls < 2:

            self._thread_local.num_401_calls += 1
            pat = re.compile(r"digest ", flags=re.IGNORECASE)
            self._thread_local.chal = parse_dict_header(pat.sub("", s_auth, count=1))

            # Consume content and release the original connection
            # to allow our new request to reuse the same one.
            r.content
            r.close()
            prep = r.request.copy()
            extract_cookies_to_jar(prep._cookies, r.request, r.raw)
            prep.prepare_cookies(prep._cookies)

            prep.headers["Authorization"] = self.build_digest_header(
                prep.method, prep.url
            )
            _r = r.connection.send(prep, **kwargs)
            _r.history.append(r)
            _r.request = prep

            return _r

        self._thread_local.num_401_calls = 1
        return r

    def __call__(self, r):
        # Initialize per-thread state, if needed
        self.init_per_thread_state()
        # If we have a saved nonce, skip the 401
        if self._thread_local.last_nonce:
            r.headers["Authorization"] = self.build_digest_header(r.method, r.url)
        try:
            self._thread_local.pos = r.body.tell()
        except AttributeError:
            # In the case of HTTPDigestAuth being reused and the body of
            # the previous request was a file-like object, pos has the
            # file position of the previous body. Ensure it's set to
            # None.
            self._thread_local.pos = None
        r.register_hook("response", self.handle_401)
        r.register_hook("response", self.handle_redirect)
        self._thread_local.num_401_calls = 1

        return r

    def __eq__(self, other):
        return all(
            [
                self.username == getattr(other, "username", None),
                self.password == getattr(other, "password", None),
            ]
        )

    def __ne__(self, other):
        return not self == other