zulip/zerver/lib/upload.py

from __future__ import absolute_import
from typing import Optional, Tuple, Mapping, Any

from django.utils.translation import ugettext as _
from django.conf import settings
from django.template.defaultfilters import slugify
from django.utils.encoding import force_text
from django.core.files import File
from django.http import HttpRequest
from jinja2 import Markup as mark_safe
import unicodedata

from zerver.lib.avatar import user_avatar_hash
from zerver.lib.request import JsonableError

from boto.s3.bucket import Bucket
from boto.s3.key import Key
from boto.s3.connection import S3Connection
from mimetypes import guess_type, guess_extension

from zerver.models import get_user_profile_by_id
from zerver.models import Attachment
from zerver.models import Realm, UserProfile

from six.moves import urllib
import base64
import os
import re
import six
from PIL import Image, ImageOps
from six import binary_type, text_type
from six.moves import cStringIO as StringIO
import random
import logging

# Performance Note:
#
# For writing files to S3, the file could either be stored in RAM
# (if it is less than 2.5MiB or so) or an actual temporary file on disk.
#
# Because we set FILE_UPLOAD_MAX_MEMORY_SIZE to 0, only the latter case
# should occur in practice.
#
# This is great, because passing the pseudofile object that Django gives
# you to boto would be a pain.

# To come up with a s3 key we randomly generate a "directory". The
# "file name" is the original filename provided by the user run
# through a sanitization function.

def sanitize_name(value):
    # type: (six.text_type) -> str
    """
    Sanitizes a value to be safe to store in a Linux filesystem, in
    S3, and in a URL.  So unicode is allowed, but not special
    characters other than ".", "-", and "_".

    This implementation is based on django.utils.text.slugify; it is
    modified by:
    * hardcoding allow_unicode=True.
    * adding '.' and '_' to the list of allowed characters.
    * preserving the case of the value.
    """
    value = force_text(value)
    value = unicodedata.normalize('NFKC', value)
    value = re.sub('[^\w\s._-]', '', value, flags=re.U).strip()
    return mark_safe(re.sub('[-\s]+', '-', value, flags=re.U))

def random_name(bytes=60):
    # type: (int) -> str
    return base64.urlsafe_b64encode(os.urandom(bytes))

class BadImageError(JsonableError):
    pass

def resize_avatar(image_data):
    # type: (str) -> str
    AVATAR_SIZE = 100
    try:
        im = Image.open(StringIO(image_data))
        im = ImageOps.fit(im, (AVATAR_SIZE, AVATAR_SIZE), Image.ANTIALIAS)
    except IOError:
        raise BadImageError("Could not decode avatar image; did you upload an image file?")
    out = StringIO()
    im.save(out, format='png')
    return out.getvalue()

### Common

class ZulipUploadBackend(object):
    def upload_message_image(self, uploaded_file_name, content_type, file_data, user_profile, target_realm=None):
        # type: (str, str, str, UserProfile, Optional[Realm]) -> str
        raise NotImplementedError()

    def upload_avatar_image(self, user_file, user_profile, email):
        # type: (File, UserProfile, text_type) -> None
        raise NotImplementedError()

    def delete_message_image(self, path_id):
        # type: (text_type) -> bool
        raise NotImplementedError()

### S3

def get_bucket(conn, bucket_name):
    # type: (S3Connection, text_type) -> Bucket
    # Calling get_bucket() with validate=True can apparently lead
    # to expensive S3 bills:
    #    http://www.appneta.com/blog/s3-list-get-bucket-default/
    # The benefits of validation aren't completely clear to us, and
    # we want to save on our bills, so we set the validate flag to False.
    # (We think setting validate to True would cause us to fail faster
    #  in situations where buckets don't exist, but that shouldn't be
    #  an issue for us.)
    bucket = conn.get_bucket(bucket_name, validate=False)
    return bucket

def upload_image_to_s3(
        bucket_name,
        file_name,
        content_type,
        user_profile,
        contents,
    ):
    # type: (text_type, text_type, text_type, UserProfile, text_type) -> None

    conn = S3Connection(settings.S3_KEY, settings.S3_SECRET_KEY)
    bucket = get_bucket(conn, bucket_name)
    key = Key(bucket)
    key.key = file_name
    key.set_metadata("user_profile_id", str(user_profile.id))
    key.set_metadata("realm_id", str(user_profile.realm.id))

    if content_type:
        headers = {'Content-Type': content_type}
    else:
        headers = None

    key.set_contents_from_string(contents, headers=headers)

def get_file_info(request, user_file):
    # type: (HttpRequest, File) -> Tuple[str, str]

    # `user_file.name` is a unicode whereas it should be an ascii
    # so convert it into an ascii.
    uploaded_file_name = user_file.name.encode('ascii')
    content_type = request.GET.get('mimetype')
    if content_type is None:
        content_type = guess_type(uploaded_file_name)[0]
    else:
        uploaded_file_name = uploaded_file_name + guess_extension(content_type)

    uploaded_file_name = urllib.parse.unquote(uploaded_file_name).decode('utf-8')
    return uploaded_file_name, content_type


def get_signed_upload_url(path):
    # type: (str) -> str
    conn = S3Connection(settings.S3_KEY, settings.S3_SECRET_KEY)
    return conn.generate_url(15, 'GET', bucket=settings.S3_AUTH_UPLOADS_BUCKET, key=path)

def get_realm_for_filename(path):
    # type: (str) -> int
    conn = S3Connection(settings.S3_KEY, settings.S3_SECRET_KEY)
    key = get_bucket(conn, settings.S3_AUTH_UPLOADS_BUCKET).get_key(path)
    if key is None:
        # This happens if the key does not exist.
        return None
    return get_user_profile_by_id(key.metadata["user_profile_id"]).realm.id

class S3UploadBackend(ZulipUploadBackend):
    def upload_message_image(self, uploaded_file_name, content_type, file_data, user_profile, target_realm=None):
        # type: (str, str, str, UserProfile, Optional[Realm]) -> str
        bucket_name = settings.S3_AUTH_UPLOADS_BUCKET
        s3_file_name = "/".join([
            str(target_realm.id if target_realm is not None else user_profile.realm.id),
            random_name(18),
            sanitize_name(uploaded_file_name)
        ])
        url = "/user_uploads/%s" % (s3_file_name)

        upload_image_to_s3(
                bucket_name,
                s3_file_name,
                content_type,
                user_profile,
                file_data
        )

        create_attachment(uploaded_file_name, s3_file_name, user_profile)
        return url

    def delete_message_image(self, path_id):
        # type: (text_type) -> bool
        conn = S3Connection(settings.S3_KEY, settings.S3_SECRET_KEY)
        bucket = get_bucket(conn, settings.S3_AUTH_UPLOADS_BUCKET)

        # check if file exists
        key = bucket.get_key(path_id)
        if key is not None:
            bucket.delete_key(key)
            return True

        file_name = path_id.split("/")[-1]
        logging.warning("%s does not exist. Its entry in the database will be removed." % (file_name,))
        return False

    def upload_avatar_image(self, user_file, user_profile, email):
        # type: (File, UserProfile, text_type) -> None
        content_type = guess_type(user_file.name)[0]
        bucket_name = settings.S3_AVATAR_BUCKET
        s3_file_name = user_avatar_hash(email)

        image_data = user_file.read()
        upload_image_to_s3(
            bucket_name,
            s3_file_name + ".original",
            content_type,
            user_profile,
            image_data,
        )

        resized_data = resize_avatar(image_data)
        upload_image_to_s3(
            bucket_name,
            s3_file_name,
            'image/png',
            user_profile,
            resized_data,
        )
        # See avatar_url in avatar.py for URL.  (That code also handles the case
        # that users use gravatar.)

### Local

def mkdirs(path):
    # type: (str) -> None
    dirname = os.path.dirname(path)
    if not os.path.isdir(dirname):
        os.makedirs(dirname)

def write_local_file(type, path, file_data):
    # type: (text_type, text_type, binary_type) -> None
    file_path = os.path.join(settings.LOCAL_UPLOADS_DIR, type, path)
    mkdirs(file_path)
    with open(file_path, 'wb') as f:
        f.write(file_data)

def get_local_file_path(path_id):
    local_path = os.path.join(settings.LOCAL_UPLOADS_DIR, 'files', path_id)
    if os.path.isfile(local_path):
        return local_path
    else:
        return None

class LocalUploadBackend(ZulipUploadBackend):
    def upload_message_image(self, uploaded_file_name, content_type, file_data, user_profile, target_realm=None):
        # type: (str, str, str, UserProfile, Optional[Realm]) -> str
        # Split into 256 subdirectories to prevent directories from getting too big
        path = "/".join([
            str(user_profile.realm.id),
            format(random.randint(0, 255), 'x'),
            random_name(18),
            sanitize_name(uploaded_file_name)
        ])

        write_local_file('files', path, file_data)
        create_attachment(uploaded_file_name, path, user_profile)
        return '/user_uploads/' + path

    def delete_message_image(self, path_id):
        # type: (text_type) -> bool
        file_path = os.path.join(settings.LOCAL_UPLOADS_DIR, 'files', path_id)
        if os.path.isfile(file_path):
            # This removes the file but the empty folders still remain.
            os.remove(file_path)
            return True

        file_name = path_id.split("/")[-1]
        logging.warning("%s does not exist. Its entry in the database will be removed." % (file_name,))
        return False

    def upload_avatar_image(self, user_file, user_profile, email):
        # type: (File, UserProfile, text_type) -> None
        email_hash = user_avatar_hash(email)

        image_data = user_file.read()
        write_local_file('avatars', email_hash+'.original', image_data)

        resized_data = resize_avatar(image_data)
        write_local_file('avatars', email_hash+'.png', resized_data)

# Common and wrappers
if settings.LOCAL_UPLOADS_DIR is not None:
    upload_backend = LocalUploadBackend() # type: ZulipUploadBackend
else:
    upload_backend = S3UploadBackend()

def delete_message_image(path_id):
    # type: (text_type) -> bool
    return upload_backend.delete_message_image(path_id)

def upload_avatar_image(user_file, user_profile, email):
    # type: (File, UserProfile, text_type) -> None
    upload_backend.upload_avatar_image(user_file, user_profile, email)

def upload_message_image(uploaded_file_name, content_type, file_data, user_profile, target_realm=None):
    # type: (str, str, str, UserProfile, Optional[Realm]) -> str
    return upload_backend.upload_message_image(uploaded_file_name, content_type, file_data,
                                               user_profile, target_realm=target_realm)

def claim_attachment(user_profile, path_id, message, is_message_realm_public):
    # type: (UserProfile, text_type, Mapping[str, Any], bool) -> bool
    try:
        attachment = Attachment.objects.get(path_id=path_id)
        attachment.messages.add(message['message'])
        # Only the owner of the file has the right to elevate the permissions of a file.
        # This makes sure that a private file is not accidently made public by another user
        # by sending a message to a public stream that refers the private file.
        if attachment.owner == user_profile:
            attachment.is_realm_public = attachment.is_realm_public or is_message_realm_public
        attachment.save()
        return True
    except Attachment.DoesNotExist:
        raise JsonableError(_("The upload was not successful. Please reupload the file again in a new message."))
    return False

def create_attachment(file_name, path_id, user_profile):
    # type: (str, str, UserProfile) -> bool
    Attachment.objects.create(file_name=file_name, path_id=path_id, owner=user_profile, realm=user_profile.realm)
    return True

def upload_message_image_from_request(request, user_file, user_profile):
    # type: (HttpRequest, File, UserProfile) -> str
    uploaded_file_name, content_type = get_file_info(request, user_file)
    return upload_message_image(uploaded_file_name, content_type, user_file.read(), user_profile)