# -*- coding: utf-8 -*-

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

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

import os
import re
import time
import hashlib
import logging

from base64 import b64encode

from .compat import urlparse, str
from .cookies import extract_cookies_to_jar
from .utils import parse_dict_header

log = logging.getLogger(__name__)

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."""

return 'Basic ' + b64encode(('%s:%s' % (username, password)).encode('latin1')).strip().decode('latin1')


class AuthBase(object):
"""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 __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
self.last_nonce = ''
self.nonce_count = 0
self.chal = {}
self.pos = None

def build_digest_header(self, method, url):

realm = self.chal['realm']
nonce = self.chal['nonce']
qop = self.chal.get('qop')
algorithm = self.chal.get('algorithm')
opaque = self.chal.get('opaque')

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

KD = lambda s, d: hash_utf8("%s:%s" % (s, d))

if hash_utf8 is None:
return None

# XXX not implemented yet
entdig = None
p_parsed = urlparse(url)
path = p_parsed.path
if p_parsed.query:
path += '?' + p_parsed.query

A1 = '%s:%s:%s' % (self.username, realm, self.password)
A2 = '%s:%s' % (method, path)

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

if nonce == self.last_nonce:
self.nonce_count += 1
else:
self.nonce_count = 1
ncvalue = '%08x' % self.nonce_count
s = str(self.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])
noncebit = "%s:%s:%s:%s:%s" % (nonce, ncvalue, cnonce, qop, HA2)
if _algorithm == 'MD5-SESS':
HA1 = hash_utf8('%s:%s:%s' % (HA1, nonce, cnonce))

if qop is None:
respdig = KD(HA1, "%s:%s" % (nonce, HA2))
elif qop == 'auth' or 'auth' in qop.split(','):
respdig = KD(HA1, noncebit)
else:
# XXX handle auth-int.
return None

self.last_nonce = nonce

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

return 'Digest %s' % (base)

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

if self.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.pos)
num_401_calls = getattr(self, 'num_401_calls', 1)
s_auth = r.headers.get('www-authenticate', '')

if 'digest' in s_auth.lower() and num_401_calls < 2:

setattr(self, 'num_401_calls', num_401_calls + 1)
pat = re.compile(r'digest ', flags=re.IGNORECASE)
self.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.raw.release_conn()
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

setattr(self, 'num_401_calls', 1)
return r

def __call__(self, r):
# If we have a saved nonce, skip the 401
if self.last_nonce:
r.headers['Authorization'] = self.build_digest_header(r.method, r.url)
try:
self.pos = r.body.tell()
except AttributeError:
pass
r.register_hook('response', self.handle_401)
return r