keystone/keystone/common/utils.py

# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# Copyright 2011 Justin Santa Barbara
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

import base64
import hashlib
import hmac
import json
import subprocess
import sys
import urllib

from keystone import logging


def import_class(import_str):
    """Returns a class from a string including module and class."""
    mod_str, _sep, class_str = import_str.rpartition('.')
    try:
        __import__(mod_str)
        return getattr(sys.modules[mod_str], class_str)
    except (ImportError, ValueError, AttributeError), exc:
        logging.debug('Inner Exception: %s', exc)
        raise


def import_object(import_str, *args, **kw):
    """Returns an object including a module or module and class."""
    try:
        __import__(import_str)
        return sys.modules[import_str]
    except ImportError:
        cls = import_class(import_str)
        return cls(*args, **kw)


class SmarterEncoder(json.JSONEncoder):
    """Help for JSON encoding dict-like objects."""
    def default(self, obj):
        if not isinstance(obj, dict) and hasattr(obj, 'iteritems'):
            return dict(obj.iteritems())
        return super(SmarterEncoder, self).default(obj)


class Ec2Signer(object):
    """Hacked up code from boto/connection.py"""

    def __init__(self, secret_key):
        secret_key = secret_key.encode()
        self.hmac = hmac.new(secret_key, digestmod=hashlib.sha1)
        if hashlib.sha256:
            self.hmac_256 = hmac.new(secret_key, digestmod=hashlib.sha256)

    def generate(self, credentials):
        """Generate auth string according to what SignatureVersion is given."""
        if credentials.params['SignatureVersion'] == '0':
            return self._calc_signature_0(credentials.params)
        if credentials.params['SignatureVersion'] == '1':
            return self._calc_signature_1(credentials.params)
        if credentials.params['SignatureVersion'] == '2':
            return self._calc_signature_2(credentials.params,
                                          credentials.verb,
                                          credentials.host,
                                          credentials.path)
        raise Exception('Unknown Signature Version: %s' %
                        credentials.params['SignatureVersion'])

    @staticmethod
    def _get_utf8_value(value):
        """Get the UTF8-encoded version of a value."""
        if not isinstance(value, str) and not isinstance(value, unicode):
            value = str(value)
        if isinstance(value, unicode):
            return value.encode('utf-8')
        else:
            return value

    def _calc_signature_0(self, params):
        """Generate AWS signature version 0 string."""
        s = params['Action'] + params['Timestamp']
        self.hmac.update(s)
        return base64.b64encode(self.hmac.digest())

    def _calc_signature_1(self, params):
        """Generate AWS signature version 1 string."""
        keys = params.keys()
        keys.sort(cmp=lambda x, y: cmp(x.lower(), y.lower()))
        for key in keys:
            self.hmac.update(key)
            val = self._get_utf8_value(params[key])
            self.hmac.update(val)
        return base64.b64encode(self.hmac.digest())

    def _calc_signature_2(self, params, verb, server_string, path):
        """Generate AWS signature version 2 string."""
        LOG.debug('using _calc_signature_2')
        string_to_sign = '%s\n%s\n%s\n' % (verb, server_string, path)
        if self.hmac_256:
            current_hmac = self.hmac_256
            params['SignatureMethod'] = 'HmacSHA256'
        else:
            current_hmac = self.hmac
            params['SignatureMethod'] = 'HmacSHA1'
        keys = params.keys()
        keys.sort()
        pairs = []
        for key in keys:
            val = self._get_utf8_value(params[key])
            val = urllib.quote(val, safe='-_~')
            pairs.append(urllib.quote(key, safe='') + '=' + val)
        qs = '&'.join(pairs)
        LOG.debug('query string: %s', qs)
        string_to_sign += qs
        LOG.debug('string_to_sign: %s', string_to_sign)
        current_hmac.update(string_to_sign)
        b64 = base64.b64encode(current_hmac.digest())
        LOG.debug('len(b64)=%d', len(b64))
        LOG.debug('base64 encoded digest: %s', b64)
        return b64


# From python 2.7
def check_output(*popenargs, **kwargs):
  r"""Run command with arguments and return its output as a byte string.

  If the exit code was non-zero it raises a CalledProcessError.  The
  CalledProcessError object will have the return code in the returncode
  attribute and output in the output attribute.

  The arguments are the same as for the Popen constructor.  Example:

  >>> check_output(["ls", "-l", "/dev/null"])
  'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null\n'

  The stdout argument is not allowed as it is used internally.
  To capture standard error in the result, use stderr=STDOUT.

  >>> check_output(["/bin/sh", "-c",
  ...               "ls -l non_existent_file ; exit 0"],
  ...              stderr=STDOUT)
  'ls: non_existent_file: No such file or directory\n'
  """
  if 'stdout' in kwargs:
    raise ValueError('stdout argument not allowed, it will be overridden.')
  logging.debug(' '.join(popenargs[0]))
  process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
  output, unused_err = process.communicate()
  retcode = process.poll()
  if retcode:
    cmd = kwargs.get("args")
    if cmd is None:
      cmd = popenargs[0]
    raise subprocess.CalledProcessError(retcode, cmd)
  return output


def git(*args):
  return check_output(['git'] + list(args))