Synnefo

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from functools import wraps

from traceback import format_exc

from time import time

from logging import getLogger

from wsgiref.handlers import format_date_time

from django.http import HttpResponse

from django.utils import cache

from django.utils import simplejson as json

from django.template.loader import render_to_string

from django.views.decorators import csrf

from astakosclient import AstakosClient

from astakosclient.errors import AstakosClientException

from django.conf import settings

from snf_django.lib.api import faults

log = getLogger(__name__)

def get_token(request):

    """Get the Authentication Token of a request."""

    token = request.GET.get("X-Auth-Token", None)

    if not token:

        token = request.META.get("HTTP_X_AUTH_TOKEN", None)

    return token

def api_method(http_method=None, token_required=True, user_required=True,

               logger=None, format_allowed=True, astakos_url=None,

               serializations=None, strict_serlization=False):

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

    if not logger:

        logger = log

    serializations = serializations or ['json', 'xml']

    def decorator(func):

        @wraps(func)

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

            try:

                # Get the requested serialization format

                serialization = get_serialization(

                    request, format_allowed, 'json')

                # If guessed serialization is not supported, fallback to

                # the default serialization or return an API error in case

                # strict serialization flag is set.

                if not serialization in serializations:

                    if strict_serlization:

                        raise faults.BadRequest(("%s serialization not "

                                                "supported") % serialization)

                    serialization = serializations[0]

                request.serialization = serialization

                # Check HTTP method

                if http_method and request.method != http_method:

                    raise faults.BadRequest("Method not allowed")

                # Get authentication token

                request.x_auth_token = None

                if token_required or user_required:

                    token = get_token(request)

                    if not token:

                        msg = "Access denied. No authentication token"

                        raise faults.Unauthorized(msg)

                    request.x_auth_token = token

                # Authenticate

                if user_required:

                    assert(token_required), "Can not get user without token"

                    astakos = astakos_url or settings.ASTAKOS_BASE_URL

                    astakos = AstakosClient(astakos,

                                            use_pool=True,

                                            logger=logger)

                    user_info = astakos.get_user_info(token)

                    request.user_uniq = user_info["uuid"]

                    request.user = user_info

                # Get the response object

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

                # Fill in response variables

                update_response_headers(request, response)

                return response

            except faults.Fault, fault:

                if fault.code >= 500:

                    logger.exception("API ERROR")

                return render_fault(request, fault)

            except AstakosClientException as err:

                fault = faults.Fault(message=err.message,

                                     details=err.details,

                                     code=err.status)

                if fault.code >= 500:

                    logger.exception("Astakos ERROR")

                return render_fault(request, fault)

            except:

                logger.exception("Unexpected ERROR")

                fault = faults.InternalServerError("Unexpected error")

                return render_fault(request, fault)

        return csrf.csrf_exempt(wrapper)

    return decorator

def get_serialization(request, format_allowed=True, default_serialization="json"):

    """Return the serialization format requested.

    Valid formats are 'json' and 'xml' and 'text'

    """

    if not format_allowed:

        return "text"

    # Try to get serialization from 'format' parameter

    _format = request.GET.get("format")

    if _format:

        if _format == "json":

            return "json"

        elif _format == "xml":

            return "xml"

    # Try to get serialization from path

    path = request.path

    if path.endswith(".json"):

        return "json"

    elif path.endswith(".xml"):

        return "xml"

    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"

    return default_serialization

def update_response_headers(request, response):

    if not getattr(response, "override_serialization", False):

        serialization = request.serialization

        if serialization == "xml":

            response["Content-Type"] = "application/xml; charset=UTF-8"

        elif serialization == "json":

            response["Content-Type"] = "application/json; charset=UTF-8"

        elif serialization == "text":

            response["Content-Type"] = "text/plain; charset=UTF-8"

        else:

            raise ValueError("Unknown serialization format '%s'" %

                             serialization)

    if settings.DEBUG or getattr(settings, "TEST", False):

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

    if not response.has_header("Content-Length"):

        response["Content-Length"] = len(response.content)

    cache.add_never_cache_headers(response)

    # Fix Vary and Cache-Control Headers. Issue: #3448

    cache.patch_vary_headers(response, ('X-Auth-Token',))

    cache.patch_cache_control(response, no_cache=True, no_store=True,

                              must_revalidate=True)

def render_fault(request, fault):

    """Render an API fault to an HTTP response."""

    # If running in debug mode add exception information to fault details

    if settings.DEBUG or getattr(settings, "TEST", False):

        fault.details = format_exc()

    try:

        serialization = request.serialization

    except AttributeError:

        request.serialization = "json"

        serialization = "json"

    # Serialize the fault data to xml or json

    if 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)

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

    update_response_headers(request, response)

    return response

@api_method(token_required=False, user_required=False)

def api_endpoint_not_found(request):

    raise faults.BadRequest("API endpoint not found")

@api_method(token_required=False, user_required=False)

def api_method_not_allowed(request):

    raise faults.BadRequest('Method not allowed')

def allow_jsonp(key='callback'):

    """

    Wrapper to enable jsonp responses.

    """

    def wrapper(func):

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

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

            if 'content-type' in response._headers and \

               response._headers['content-type'][1] == 'application/json':

                callback_name = request.GET.get(key, None)

                if callback_name:

                    response.content = "%s(%s)" % (callback_name,

                                                   response.content)

                    response._headers['content-type'] = ('Content-Type',

                                                         'text/javascript')

            return response

        return view_wrapper

    return wrapper