39

我有一个应用程序可以让人们上传文件，表示为UploadedFiles. 但是，我想确保用户只上传 xml 文件。我知道我可以使用 来做到这一点magic，但我不知道在哪里放置这个检查 - 我不能把它放在函数中，因为据我所知，运行clean时文件尚未上传。clean

这是UploadedFile模型：

class UploadedFile(models.Model):
    """This represents a file that has been uploaded to the server."""
    STATE_UPLOADED = 0
    STATE_ANNOTATED = 1
    STATE_PROCESSING = 2
    STATE_PROCESSED = 4
    STATES = (
        (STATE_UPLOADED, "Uploaded"),
        (STATE_ANNOTATED, "Annotated"),
        (STATE_PROCESSING, "Processing"),
        (STATE_PROCESSED, "Processed"),
    )

    status = models.SmallIntegerField(choices=STATES,
        default=0, blank=True, null=True) 
    file = models.FileField(upload_to=settings.XML_ROOT)
    project = models.ForeignKey(Project)

    def __unicode__(self):
        return self.file.name

    def name(self):
        return os.path.basename(self.file.name)

    def save(self, *args, **kwargs):
        if not self.status:
            self.status = self.STATE_UPLOADED
        super(UploadedFile, self).save(*args, **kwargs)

    def delete(self, *args, **kwargs):
        os.remove(self.file.path)
        self.file.delete(False)
        super(UploadedFile, self).delete(*args, **kwargs)

    def get_absolute_url(self):
        return u'/upload/projects/%d' % self.id

    def clean(self):
        if not "XML" in magic.from_file(self.file.url):
            raise ValidationError(u'Not an xml file.')

class UploadedFileForm(forms.ModelForm):
    class Meta:                
        model = UploadedFile
        exclude = ('project',)
4

5 回答 5

34

验证文件是一个常见的挑战，所以我想使用一个验证器：

import magic

from django.utils.deconstruct import deconstructible
from django.template.defaultfilters import filesizeformat


@deconstructible
class FileValidator(object):
    error_messages = {
     'max_size': ("Ensure this file size is not greater than %(max_size)s."
                  " Your file size is %(size)s."),
     'min_size': ("Ensure this file size is not less than %(min_size)s. "
                  "Your file size is %(size)s."),
     'content_type': "Files of type %(content_type)s are not supported.",
    }

    def __init__(self, max_size=None, min_size=None, content_types=()):
        self.max_size = max_size
        self.min_size = min_size
        self.content_types = content_types

    def __call__(self, data):
        if self.max_size is not None and data.size > self.max_size:
            params = {
                'max_size': filesizeformat(self.max_size), 
                'size': filesizeformat(data.size),
            }
            raise ValidationError(self.error_messages['max_size'],
                                   'max_size', params)

        if self.min_size is not None and data.size < self.min_size:
            params = {
                'min_size': filesizeformat(self.min_size),
                'size': filesizeformat(data.size)
            }
            raise ValidationError(self.error_messages['min_size'], 
                                   'min_size', params)

        if self.content_types:
            content_type = magic.from_buffer(data.read(), mime=True)
            data.seek(0)

            if content_type not in self.content_types:
                params = { 'content_type': content_type }
                raise ValidationError(self.error_messages['content_type'],
                                   'content_type', params)

    def __eq__(self, other):
        return (
            isinstance(other, FileValidator) and
            self.max_size == other.max_size and
            self.min_size == other.min_size and
            self.content_types == other.content_types
        )

然后你可以FileValidator在你的models.FileField或forms.FileField如下使用：

validate_file = FileValidator(max_size=1024 * 100, 
                             content_types=('application/xml',))
file = models.FileField(upload_to=settings.XML_ROOT, 
                        validators=[validate_file])
于 2015-01-13T07:05:26.407 回答
31

从 django 1.11 开始，您还可以使用 FileExtensionValidator。

from django.core.validators import FileExtensionValidator
class UploadedFile(models.Model):
    file = models.FileField(upload_to=settings.XML_ROOT, 
        validators=[FileExtensionValidator(allowed_extensions=['xml'])])

请注意，这必须在 FileField 上使用，并且不能在 CharField 上使用（例如），因为验证器在 value.name 上进行验证。

参考：https ://docs.djangoproject.com/en/dev/ref/validators/#fileextensionvalidator

于 2018-01-03T13:20:50.030 回答
18

对于后代：解决方案是使用该read方法并将其传递给magic.from_buffer.

class UploadedFileForm(ModelForm):
    def clean_file(self):
        file = self.cleaned_data.get("file", False)
        filetype = magic.from_buffer(file.read())
        if not "XML" in filetype:
            raise ValidationError("File is not XML.")
        return file

    class Meta:
        model = models.UploadedFile
        exclude = ('project',)
于 2013-12-01T02:09:23.467 回答
4

我认为您想要做的是在 Django 的Form.clean_your_field_name_here()方法中清理上传的文件 - 如果数据是作为正常的 HTTP POST 请求提交的，那么到那时您的系统上就可以使用数据了。

此外，如果您认为这种效率低下，请探索不同 Django 文件上传后端的选项以及如何进行流处理。

如果在处理上传时需要考虑系统的安全性

  • 确保上传的文件具有正确的扩展名

  • 确保 mimetype 与文件扩展名匹配

如果您担心用户上传漏洞利用文件（用于攻击您的网站）

  • 在保存时重写所有文件内容以消除可能的额外（利用）有效负载（因此您不能在 XML 中嵌入 HTML，浏览器在下载时会将其解释为站点源 HTML 文件）

  • 确保在下载时使用 content-disposition 标头

更多信息：http: //opensourcehacker.com/2013/07/31/secure-user-uploads-and-exploiting-served-user-content/

以下是我如何清理上传的图像的示例：

class Example(models.Model):
    image = models.ImageField(upload_to=filename_gen("participant-images/"), blank=True, null=True)


class Example(forms.ModelForm):
    def clean_image(self):
        """ Clean the uploaded image attachemnt.
        """
        image = self.cleaned_data.get('image', False)
        utils.ensure_safe_user_image(image)
        return image


def ensure_safe_user_image(image):
    """ Perform various checks to sanitize user uploaded image data.

    Checks that image was valid header, then

    :param: InMemoryUploadedFile instance (Django form field value)

    :raise: ValidationError in the case the image content has issues
    """

    if not image:
        return

    assert isinstance(image, InMemoryUploadedFile), "Image rewrite has been only tested on in-memory upload backend"

    # Make sure the image is not too big, so that PIL trashes the server
    if image:
        if image._size > 4*1024*1024:
            raise ValidationError("Image file too large - the limit is 4 megabytes")

    # Then do header peak what the image claims
    image.file.seek(0)
    mime = magic.from_buffer(image.file.getvalue(), mime=True)
    if mime not in ("image/png", "image/jpeg"):
        raise ValidationError("Image is not valid. Please upload a JPEG or PNG image.")

    doc_type = mime.split("/")[-1].upper()

    # Read data from cStringIO instance
    image.file.seek(0)
    pil_image = Image.open(image.file)

    # Rewrite the image contents in the memory
    # (bails out with exception on bad data)
    buf = StringIO()
    pil_image.thumbnail((2048, 2048), Image.ANTIALIAS)
    pil_image.save(buf, doc_type)
    image.file = buf

    # Make sure the image has valid extension (can't upload .htm image)
    extension = unicode(doc_type.lower())
    if not image.name.endswith(u".%s" % extension):
        image.name = image.name + u"." + extension
于 2013-11-29T09:09:31.273 回答
2

我最近发现了一个有趣的包，它可以进行上传文件验证。你可以在这里看到包。封装方法与 sultan answer 类似，因此我们可以立即实施。

from upload_validator import FileTypeValidator

validator = FileTypeValidator(
    allowed_types=['application/msword'],
    allowed_extensions=['.doc', '.docx']
)

file_resource = open('sample.doc')

# ValidationError will be raised in case of invalid type or extension
validator(file_resource)
于 2020-11-15T13:48:23.423 回答