Synnefo

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import datetime

from base64 import b64encode

from datetime import timedelta, tzinfo

from functools import wraps

from hashlib import sha256

from logging import getLogger

from random import choice

from string import digits, lowercase, uppercase

from time import time

from traceback import format_exc

from wsgiref.handlers import format_date_time

import dateutil.parser

from Crypto.Cipher import AES

from django.conf import settings

from django.http import HttpResponse

from django.template.loader import render_to_string

from django.utils import simplejson as json

from django.utils.cache import add_never_cache_headers

from synnefo.api.faults import (Fault, BadRequest, BuildInProgress,

                                ItemNotFound, ServiceUnavailable, Unauthorized)

from synnefo.db.models import (Flavor, VirtualMachine, VirtualMachineMetadata,

                               Network, NetworkInterface)

from synnefo.plankton.backend import ImageBackend

log = getLogger('synnefo.api')

class UTC(tzinfo):

    def utcoffset(self, dt):

        return timedelta(0)

    def tzname(self, dt):

        return 'UTC'

    def dst(self, dt):

        return timedelta(0)

def isoformat(d):

    """Return an ISO8601 date string that includes a timezone."""

    return d.replace(tzinfo=UTC()).isoformat()

def isoparse(s):

    """Parse an ISO8601 date string into a datetime object."""

    if not s:

        return None

    try:

        since = dateutil.parser.parse(s)

        utc_since = since.astimezone(UTC()).replace(tzinfo=None)

    except ValueError:

        raise BadRequest('Invalid changes-since parameter.')

    now = datetime.datetime.now()

    if utc_since > now:

        raise BadRequest('changes-since value set in the future.')

    if now - utc_since > timedelta(seconds=settings.POLL_LIMIT):

        raise BadRequest('Too old changes-since value.')

    return utc_since

def random_password():

    """Generates a random password

    We generate a windows compliant password: it must contain at least

    one charachter from each of the groups: upper case, lower case, digits.

    """

    pool = lowercase + uppercase + digits

    lowerset = set(lowercase)

    upperset = set(uppercase)

    digitset = set(digits)

    length = 10

    password = ''.join(choice(pool) for i in range(length - 2))

    # Make sure the password is compliant

    chars = set(password)

    if not chars & lowerset:

        password += choice(lowercase)

    if not chars & upperset:

        password += choice(uppercase)

    if not chars & digitset:

        password += choice(digits)

    # Pad if necessary to reach required length

    password += ''.join(choice(pool) for i in range(length - len(password)))

    return password

def zeropad(s):

    """Add zeros at the end of a string in order to make its length

       a multiple of 16."""

    npad = 16 - len(s) % 16

    return s + '\x00' * npad

def encrypt(plaintext):

    # Make sure key is 32 bytes long

    key = sha256(settings.SECRET_KEY).digest()

    aes = AES.new(key)

    enc = aes.encrypt(zeropad(plaintext))

    return b64encode(enc)

def get_vm(server_id, user_id):

    """Return a VirtualMachine instance or raise ItemNotFound."""

    try:

        server_id = int(server_id)

        return VirtualMachine.objects.get(id=server_id, userid=user_id)

    except ValueError:

        raise BadRequest('Invalid server ID.')

    except VirtualMachine.DoesNotExist:

        raise ItemNotFound('Server not found.')

def get_vm_meta(vm, key):

    """Return a VirtualMachineMetadata instance or raise ItemNotFound."""

    try:

        return VirtualMachineMetadata.objects.get(meta_key=key, vm=vm)

    except VirtualMachineMetadata.DoesNotExist:

        raise ItemNotFound('Metadata key not found.')

def get_image(image_id, user_id):

    """Return an Image instance or raise ItemNotFound."""

    backend = ImageBackend(user_id)

    try:

        image = backend.get_image(image_id)

        if not image:

            raise ItemNotFound('Image not found.')

        return image

    finally:

        backend.close()

def get_flavor(flavor_id):

    """Return a Flavor instance or raise ItemNotFound."""

    try:

        flavor_id = int(flavor_id)

        return Flavor.objects.get(id=flavor_id)

    except (ValueError, Flavor.DoesNotExist):

        raise ItemNotFound('Flavor not found.')

def get_network(network_id, user_id):

    """Return a Network instance or raise ItemNotFound."""

    try:

        if network_id == 'public':

            return Network.objects.get(public=True)

        else:

            network_id = int(network_id)

            return Network.objects.get(id=network_id, userid=user_id)

    except (ValueError, Network.DoesNotExist):

        raise ItemNotFound('Network not found.')

def get_nic(machine, network):

    try:

        return NetworkInterface.objects.get(machine=machine, network=network)

    except NetworkInterface.DoesNotExist:

        raise ItemNotFound('Server not connected to this network.')

def get_request_dict(request):

    """Returns data sent by the client as a python dict."""

    data = request.raw_post_data

    if request.META.get('CONTENT_TYPE').startswith('application/json'):

        try:

            return json.loads(data)

        except ValueError:

            raise BadRequest('Invalid JSON data.')

    else:

        raise BadRequest('Unsupported Content-Type.')

def update_response_headers(request, response):

    if request.serialization == 'xml':

        response['Content-Type'] = 'application/xml'

    elif request.serialization == 'atom':

        response['Content-Type'] = 'application/atom+xml'

    else:

        response['Content-Type'] = 'application/json'

    if settings.TEST:

        response['Date'] = format_date_time(time())

    add_never_cache_headers(response)

def render_metadata(request, metadata, use_values=False, status=200):

    if request.serialization == 'xml':

        data = render_to_string('metadata.xml', {'metadata': metadata})

    else:

        if use_values:

            d = {'metadata': {'values': metadata}}

        else:

            d = {'metadata': metadata}

        data = json.dumps(d)

    return HttpResponse(data, status=status)

def render_meta(request, meta, status=200):

    if request.serialization == 'xml':

        data = render_to_string('meta.xml', dict(key=key, val=val))

    else:

        data = json.dumps(dict(meta=meta))

    return HttpResponse(data, status=status)

def render_fault(request, fault):

    if settings.DEBUG or settings.TEST:

        fault.details = format_exc(fault)

    if request.serialization == 'xml':

        data = render_to_string('fault.xml', {'fault': fault})

    else:

        d = {fault.name: {

                'code': fault.code,

                'message': fault.message,

                'details': fault.details}}

        data = json.dumps(d)

    resp = HttpResponse(data, status=fault.code)

    update_response_headers(request, resp)

    return resp

def request_serialization(request, atom_allowed=False):

    """Return the serialization format requested.

    Valid formats are 'json', 'xml' and 'atom' if `atom_allowed` is True.

    """

    path = request.path

    if path.endswith('.json'):

        return 'json'

    elif path.endswith('.xml'):

        return 'xml'

    elif atom_allowed and path.endswith('.atom'):

        return 'atom'

    for item in request.META.get('HTTP_ACCEPT', '').split(','):

        accept, sep, rest = item.strip().partition(';')

        if accept == 'application/json':

            return 'json'

        elif accept == 'application/xml':

            return 'xml'

        elif atom_allowed and accept == 'application/atom+xml':

            return 'atom'

    return 'json'

def api_method(http_method=None, atom_allowed=False):

    """Decorator function for views that implement an API method."""

    def decorator(func):

        @wraps(func)

        def wrapper(request, *args, **kwargs):

            try:

                request.serialization = request_serialization(request,

                                                              atom_allowed)

                if not request.user:

                    raise Unauthorized('No user found.')

                if http_method and request.method != http_method:

                    raise BadRequest('Method not allowed.')

                resp = func(request, *args, **kwargs)

                update_response_headers(request, resp)

                return resp

            except VirtualMachine.DeletedError:

                fault = BadRequest('Server has been deleted.')

                return render_fault(request, fault)

            except VirtualMachine.BuildingError:

                fault = BuildInProgress('Server is being built.')

                return render_fault(request, fault)

            except Fault, fault:

                return render_fault(request, fault)

            except BaseException, e:

                log.exception('Unexpected error')

                fault = ServiceUnavailable('Unexpected error.')

                return render_fault(request, fault)

        return wrapper

    return decorator