Synnefo » Pithos

# Copyright 2011 GRNET S.A. All rights reserved.

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#      disclaimer.

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#      disclaimer in the documentation and/or other materials

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from functools import wraps

from time import time

from traceback import format_exc

from wsgiref.handlers import format_date_time

from binascii import hexlify

from django.conf import settings

from django.http import HttpResponse

from django.utils.http import http_date, parse_etags

from pithos.api.compat import parse_http_date_safe

from pithos.api.faults import (Fault, NotModified, BadRequest, ItemNotFound, LengthRequired,

                                PreconditionFailed, RangeNotSatisfiable, ServiceUnavailable)

from pithos.backends import backend

import datetime

import logging

import re

import hashlib

import uuid

logger = logging.getLogger(__name__)

def printable_meta_dict(d):

    """Format a meta dictionary for printing out json/xml.

    Convert all keys to lower case and replace dashes to underscores.

    Change 'modified' key from backend to 'last_modified' and format date.

    """

    if 'modified' in d:

        d['last_modified'] = datetime.datetime.fromtimestamp(int(d['modified'])).isoformat()

        del(d['modified'])

    return dict([(k.lower().replace('-', '_'), v) for k, v in d.iteritems()])

def format_meta_key(k):

    """Convert underscores to dashes and capitalize intra-dash strings."""

    return '-'.join([x.capitalize() for x in k.replace('_', '-').split('-')])

def get_meta_prefix(request, prefix):

    """Get all prefix-* request headers in a dict. Reformat keys with format_meta_key()."""

    prefix = 'HTTP_' + prefix.upper().replace('-', '_')

    return dict([(format_meta_key(k[5:]), v) for k, v in request.META.iteritems() if k.startswith(prefix)])

def get_account_meta(request):

    """Get metadata from an account request."""

    meta = get_meta_prefix(request, 'X-Account-Meta-')    

    return meta

def put_account_meta(response, meta):

    """Put metadata in an account response."""

    response['X-Account-Container-Count'] = meta['count']

    response['X-Account-Bytes-Used'] = meta['bytes']

    if 'modified' in meta:

        response['Last-Modified'] = http_date(int(meta['modified']))

    for k in [x for x in meta.keys() if x.startswith('X-Account-Meta-')]:

        response[k.encode('utf-8')] = meta[k].encode('utf-8')

    if 'until_timestamp' in meta:

        response['X-Account-Until-Timestamp'] = http_date(int(meta['until_timestamp']))

def get_container_meta(request):

    """Get metadata from a container request."""

    meta = get_meta_prefix(request, 'X-Container-Meta-')

    return meta

def put_container_meta(response, meta):

    """Put metadata in a container response."""

    response['X-Container-Object-Count'] = meta['count']

    response['X-Container-Bytes-Used'] = meta['bytes']

    response['Last-Modified'] = http_date(int(meta['modified']))

    for k in [x for x in meta.keys() if x.startswith('X-Container-Meta-')]:

        response[k.encode('utf-8')] = meta[k].encode('utf-8')

    response['X-Container-Object-Meta'] = [x[14:] for x in meta['object_meta'] if x.startswith('X-Object-Meta-')]

    response['X-Container-Block-Size'] = backend.block_size

    response['X-Container-Block-Hash'] = backend.hash_algorithm

    if 'until_timestamp' in meta:

        response['X-Container-Until-Timestamp'] = http_date(int(meta['until_timestamp']))

def get_object_meta(request):

    """Get metadata from an object request."""

    meta = get_meta_prefix(request, 'X-Object-Meta-')

    if request.META.get('CONTENT_TYPE'):

        meta['Content-Type'] = request.META['CONTENT_TYPE']

    if request.META.get('HTTP_CONTENT_ENCODING'):

        meta['Content-Encoding'] = request.META['HTTP_CONTENT_ENCODING']

    if request.META.get('HTTP_CONTENT_DISPOSITION'):

        meta['Content-Disposition'] = request.META['HTTP_CONTENT_DISPOSITION']

    if request.META.get('HTTP_X_OBJECT_MANIFEST'):

        meta['X-Object-Manifest'] = request.META['HTTP_X_OBJECT_MANIFEST']

    if request.META.get('HTTP_X_OBJECT_PUBLIC'):

        meta['X-Object-Public'] = request.META['HTTP_X_OBJECT_PUBLIC']

    return meta

def put_object_meta(response, meta, public=False):

    """Put metadata in an object response."""

    response['ETag'] = meta['hash']

    response['Content-Length'] = meta['bytes']

    response['Content-Type'] = meta.get('Content-Type', 'application/octet-stream')

    response['Last-Modified'] = http_date(int(meta['modified']))

    if not public:

        response['X-Object-Version'] = meta['version']

        response['X-Object-Version-Timestamp'] = meta['version_timestamp']

        for k in [x for x in meta.keys() if x.startswith('X-Object-Meta-')]:

            response[k.encode('utf-8')] = meta[k].encode('utf-8')

        for k in ('Content-Encoding', 'Content-Disposition', 'X-Object-Manifest', 'X-Object-Public'):

            if k in meta:

                response[k] = meta[k]

    else:

        for k in ('Content-Encoding', 'Content-Disposition', 'X-Object-Manifest'):

            if k in meta:

                response[k] = meta[k]

def validate_modification_preconditions(request, meta):

    """Check that the modified timestamp conforms with the preconditions set."""

    if 'modified' not in meta:

        return # TODO: Always return?

    if_modified_since = request.META.get('HTTP_IF_MODIFIED_SINCE')

    if if_modified_since is not None:

        if_modified_since = parse_http_date_safe(if_modified_since)

    if if_modified_since is not None and int(meta['modified']) <= if_modified_since:

        raise NotModified('Resource has not been modified')

    if_unmodified_since = request.META.get('HTTP_IF_UNMODIFIED_SINCE')

    if if_unmodified_since is not None:

        if_unmodified_since = parse_http_date_safe(if_unmodified_since)

    if if_unmodified_since is not None and int(meta['modified']) > if_unmodified_since:

        raise PreconditionFailed('Resource has been modified')

def validate_matching_preconditions(request, meta):

    """Check that the ETag conforms with the preconditions set."""

    if 'hash' not in meta:

        return # TODO: Always return?

    if_match = request.META.get('HTTP_IF_MATCH')

    if if_match is not None and if_match != '*':

        if meta['hash'] not in [x.lower() for x in parse_etags(if_match)]:

            raise PreconditionFailed('Resource Etag does not match')

    if_none_match = request.META.get('HTTP_IF_NONE_MATCH')

    if if_none_match is not None:

        if if_none_match == '*' or meta['hash'] in [x.lower() for x in parse_etags(if_none_match)]:

            raise NotModified('Resource Etag matches')

def split_container_object_string(s):

    parts = s.split('/')

    if len(parts) < 3 or parts[0] != '':

        raise ValueError

    return parts[1], '/'.join(parts[2:])

def copy_or_move_object(request, v_account, src_container, src_name, dest_container, dest_name, move=False):

    """Copy or move an object."""

    meta = get_object_meta(request)

    # Keep previous values of 'Content-Type' (if a new one is absent) and 'hash'.

    try:

        src_meta = backend.get_object_meta(request.user, v_account, src_container, src_name)

    except NameError:

        raise ItemNotFound('Container or object does not exist')

    if 'Content-Type' in meta and 'Content-Type' in src_meta:

        del(src_meta['Content-Type'])

    for k in ('Content-Type', 'hash'):

        if k in src_meta:

            meta[k] = src_meta[k]

    src_version = request.META.get('HTTP_X_SOURCE_VERSION')

    try:

        if move:

            backend.move_object(request.user, v_account, src_container, src_name, dest_container, dest_name, meta, True, src_version)

        else:

            backend.copy_object(request.user, v_account, src_container, src_name, dest_container, dest_name, meta, True, src_version)

    except NameError:

        raise ItemNotFound('Container or object does not exist')

def get_int_parameter(request, name):

    p = request.GET.get(name)

    if p is not None:

        try:

            p = int(p)

        except ValueError:

            return None

        if p < 0:

            return None

    return p

def get_content_length(request):

    content_length = request.META.get('CONTENT_LENGTH')

    if not content_length:

        raise LengthRequired('Missing Content-Length header')

    try:

        content_length = int(content_length)

        if content_length < 0:

            raise ValueError

    except ValueError:

        raise BadRequest('Invalid Content-Length header')

    return content_length

def get_range(request, size):

    """Parse a Range header from the request.

    Either returns None, when the header is not existent or should be ignored,

    or a list of (offset, length) tuples - should be further checked.

    """

    ranges = request.META.get('HTTP_RANGE', '').replace(' ', '')

    if not ranges.startswith('bytes='):

        return None

    ret = []

    for r in (x.strip() for x in ranges[6:].split(',')):

        p = re.compile('^(?P<offset>\d*)-(?P<upto>\d*)$')

        m = p.match(r)

        if not m:

            return None

        offset = m.group('offset')

        upto = m.group('upto')

        if offset == '' and upto == '':

            return None

        if offset != '':

            offset = int(offset)

            if upto != '':

                upto = int(upto)

                if offset > upto:

                    return None

                ret.append((offset, upto - offset + 1))

            else:

                ret.append((offset, size - offset))

        else:

            length = int(upto)

            ret.append((size - length, length))

    return ret

def get_content_range(request):

    """Parse a Content-Range header from the request.

    Either returns None, when the header is not existent or should be ignored,

    or an (offset, length, total) tuple - check as length, total may be None.

    Returns (None, None, None) if the provided range is '*/*'.

    """

    ranges = request.META.get('HTTP_CONTENT_RANGE', '')

    if not ranges:

        return None

    p = re.compile('^bytes (?P<offset>\d+)-(?P<upto>\d*)/(?P<total>(\d+|\*))$')

    m = p.match(ranges)

    if not m:

        if ranges == 'bytes */*':

            return (None, None, None)

        return None

    offset = int(m.group('offset'))

    upto = m.group('upto')

    total = m.group('total')

    if upto != '':

        upto = int(upto)

    else:

        upto = None

    if total != '*':

        total = int(total)

    else:

        total = None

    if (upto is not None and offset > upto) or \

        (total is not None and offset >= total) or \

        (total is not None and upto is not None and upto >= total):

        return None

    if upto is None:

        length = None

    else:

        length = upto - offset + 1

    return (offset, length, total)

def raw_input_socket(request):

    """Return the socket for reading the rest of the request."""

    server_software = request.META.get('SERVER_SOFTWARE')

    if not server_software:

        if 'wsgi.input' in request.environ:

            return request.environ['wsgi.input']

        raise ServiceUnavailable('Unknown server software')

    if server_software.startswith('WSGIServer'):

        return request.environ['wsgi.input']

    elif server_software.startswith('mod_python'):

        return request._req

    raise ServiceUnavailable('Unknown server software')

MAX_UPLOAD_SIZE = 10 * (1024 * 1024) # 10MB

def socket_read_iterator(sock, length=0, blocksize=4096):

    """Return a maximum of blocksize data read from the socket in each iteration.

    Read up to 'length'. If 'length' is negative, will attempt a chunked read.

    The maximum ammount of data read is controlled by MAX_UPLOAD_SIZE.

    """

    if length < 0: # Chunked transfers

        data = ''

        while length < MAX_UPLOAD_SIZE:

            # Get chunk size.

            if hasattr(sock, 'readline'):

                chunk_length = sock.readline()

            else:

                chunk_length = ''

                while chunk_length[-1:] != '\n':

                    chunk_length += sock.read(1)

                chunk_length.strip()

            pos = chunk_length.find(';')

            if pos >= 0:

                chunk_length = chunk_length[:pos]

            try:

                chunk_length = int(chunk_length, 16)

            except Exception, e:

                raise BadRequest('Bad chunk size') # TODO: Change to something more appropriate.

            # Check if done.

            if chunk_length == 0:

                if len(data) > 0:

                    yield data

                return

            # Get the actual data.

            while chunk_length > 0:

                chunk = sock.read(min(chunk_length, blocksize))

                chunk_length -= len(chunk)

                length += len(chunk)

                data += chunk

                if len(data) >= blocksize:

                    ret = data[:blocksize]

                    data = data[blocksize:]

                    yield ret

            sock.read(2) # CRLF

        # TODO: Raise something to note that maximum size is reached.

    else:

        if length > MAX_UPLOAD_SIZE:

            # TODO: Raise something to note that maximum size is reached.

            pass

        while length > 0:

            data = sock.read(min(length, blocksize))

            length -= len(data)

            yield data

class ObjectWrapper(object):

    """Return the object's data block-per-block in each iteration.

    Read from the object using the offset and length provided in each entry of the range list.

    """

    def __init__(self, ranges, size, hashmap, boundary):

        self.ranges = ranges

        self.size = size

        self.hashmap = hashmap

        self.boundary = boundary

        self.block_index = -1

        self.block = ''

        self.range_index = -1

        self.offset, self.length = self.ranges[0]

    def __iter__(self):

        return self

    def part_iterator(self):

        if self.length > 0:

            # Get the block for the current offset.

            bi = int(self.offset / backend.block_size)

            if self.block_index != bi:

                try:

                    self.block = backend.get_block(self.hashmap[bi])

                except NameError:

                    raise ItemNotFound('Block does not exist')

                self.block_index = bi

            # Get the data from the block.

            bo = self.offset % backend.block_size

            bl = min(self.length, backend.block_size - bo)

            data = self.block[bo:bo + bl]

            self.offset += bl

            self.length -= bl

            return data

        else:

            raise StopIteration

    def next(self):

        if len(self.ranges) == 1:

            return self.part_iterator()

        if self.range_index == len(self.ranges):

            raise StopIteration

        try:

            if self.range_index == -1:

                raise StopIteration

            return self.part_iterator()

        except StopIteration:

            self.range_index += 1

            out = []

            if self.range_index < len(self.ranges):

                # Part header.

                self.offset, self.length = self.ranges[self.range_index]

                if self.range_index > 0:

                    out.append('')

                out.append('--' + self.boundary)

                out.append('Content-Range: bytes %d-%d/%d' % (self.offset, self.offset + self.length - 1, self.size))

                out.append('Content-Transfer-Encoding: binary')

                out.append('')

                out.append('')

                return '\r\n'.join(out)

            else:

                # Footer.

                out.append('')

                out.append('--' + self.boundary + '--')

                out.append('')

                return '\r\n'.join(out)

def object_data_response(request, size, hashmap, meta, public=False):

    """Get the HttpResponse object for replying with the object's data."""

    # Range handling.

    ranges = get_range(request, size)

    if ranges is None:

        ranges = [(0, size)]

        ret = 200

    else:

        check = [True for offset, length in ranges if

                    length <= 0 or length > size or

                    offset < 0 or offset >= size or

                    offset + length > size]

        if len(check) > 0:

            raise RangeNotSatisfiable('Requested range exceeds object limits')        

        ret = 206

    if ret == 206 and len(ranges) > 1:

        boundary = uuid.uuid4().hex

    else:

        boundary = ''

    wrapper = ObjectWrapper(ranges, size, hashmap, boundary)

    response = HttpResponse(wrapper, status=ret)

    put_object_meta(response, meta, public)

    if ret == 206:

        if len(ranges) == 1:

            offset, length = ranges[0]

            response['Content-Length'] = length # Update with the correct length.

            response['Content-Range'] = 'bytes %d-%d/%d' % (offset, offset + length - 1, size)

        else:

            del(response['Content-Length'])

            response['Content-Type'] = 'multipart/byteranges; boundary=%s' % (boundary,)

    return response

def hashmap_hash(hashmap):

    """Produce the root hash, treating the hashmap as a Merkle-like tree."""

    def subhash(d):

        h = hashlib.new(backend.hash_algorithm)

        h.update(d)

        return h.digest()

    if len(hashmap) == 0:

        return hexlify(subhash(''))

    if len(hashmap) == 1:

        return hexlify(subhash(hashmap[0]))

    s = 2

    while s < len(hashmap):

        s = s * 2

    h = hashmap + ([('\x00' * len(hashmap[0]))] * (s - len(hashmap)))

    h = [subhash(h[x] + (h[x + 1] if x + 1 < len(h) else '')) for x in range(0, len(h), 2)]

    while len(h) > 1:

        h = [subhash(h[x] + (h[x + 1] if x + 1 < len(h) else '')) for x in range(0, len(h), 2)]

    return hexlify(h[0])

def update_response_headers(request, response):

    if request.serialization == 'xml':

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

    elif request.serialization == 'json':

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

    elif not response['Content-Type']:

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

    if settings.TEST:

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

def render_fault(request, fault):

    if settings.DEBUG or settings.TEST:

        fault.details = format_exc(fault)

    request.serialization = 'text'

    data = '\n'.join((fault.message, fault.details)) + '\n'

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

    update_response_headers(request, response)

    return response

def request_serialization(request, format_allowed=False):

    """Return the serialization format requested.

    Valid formats are 'text' and 'json', 'xml' if 'format_allowed' is True.

    """

    if not format_allowed:

        return 'text'

    format = request.GET.get('format')

    if format == 'json':

        return 'json'

    elif format == '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' or accept == 'text/xml':

            return 'xml'

    return 'text'

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

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

    def decorator(func):

        @wraps(func)

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

            try:

                if http_method and request.method != http_method:

                    raise BadRequest('Method not allowed.')

                # The args variable may contain up to (account, container, object).

                if len(args) > 1 and len(args[1]) > 256:

                    raise BadRequest('Container name too large.')

                if len(args) > 2 and len(args[2]) > 1024:

                    raise BadRequest('Object name too large.')

                # Fill in custom request variables.

                request.serialization = request_serialization(request, format_allowed)

                # TODO: Authenticate.

                request.user = "test"

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

                update_response_headers(request, response)

                return response

            except Fault, fault:

                return render_fault(request, fault)

            except BaseException, e:

                logger.exception('Unexpected error: %s' % e)

                fault = ServiceUnavailable('Unexpected error')

                return render_fault(request, fault)

        return wrapper

    return decorator