xtractmime 0.2.1

Implementation of the MIME Sniffing standard (https://mimesniff.spec.whatwg.org/)

xtractmime

xtractmime is a BSD-licensed Python 3.7+ implementation of the MIME Sniffing Standard.

Install from PyPI:

pip install xtractmime

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Basic usage

Below mentioned are some simple examples of using xtractmime.extract_mime:

>>> from xtractmime import extract_mime
>>> extract_mime(b'Sample text content')
b'text/plain'
>>> extract_mime(b'', content_types=(b'text/html',))
b'text/html'

Additional functionality to check if a MIME type belongs to a specific MIME type group using methods included in xtractmime.mimegroups:

>>> from xtractmime.mimegroups import is_html_mime_type, is_image_mime_type
>>> mime_type = b'text/html'
>>> is_html_mime_type(mime_type)
True
>>> is_image_mime_type(mime_type)
False

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API Reference

function xtractmime.extract_mime(*args, **kwargs) -> Optional[bytes]

Parameters:

• body: bytes
• content_types: Optional[Tuple[bytes]] = None
• http_origin: bool = True
• no_sniff: bool = False
• extra_types: Optional[Tuple[Tuple[bytes, bytes, Optional[Set[bytes]], bytes], ...]] = None
• supported_types: Set[bytes] = None

Return the MIME type essence (e.g. text/html) matching the input data, or None if no match can be found.

The body parameter is the byte sequence of which MIME type is to be determined. xtractmime only considers the first few bytes of the body and the specific number of bytes read is defined in the xtractmime.RESOURCE_HEADER_BUFFER_LENGTH constant.

content_types is a tuple of MIME types given in the resource metadata. For example, for resources retrieved via HTTP, users should pass the list of MIME types mentioned in the Content-Type header.

http_origin indicates if the resource has been retrieved via HTTP (True, default) or not (False).

no_sniff is a flag which is True if the user agent does not wish to perform sniffing on the resource and False (by default) otherwise. Users may want to set this parameter to True if the X-Content-Type-Options response header is set to nosniff. For more info, see here.

extra_types is a tuple of patterns to support detecting additional MIME types. Each entry in the tuple should follow the format (Byte Pattern, Pattern Mask, Leading Bytes, MIME type):

• Byte Pattern is a byte sequence to compare with the first few bytes (xtractmime.RESOURCE_HEADER_BUFFER_LENGTH) of the body.
• Pattern Mask is a byte sequence that indicates the significance of Byte Pattern bytes: b"\xff" indicates the matching byte is strictly significant, b"\xdf" indicates that the byte is significant in an ASCII case-insensitive way, and b"\x00" indicates that the byte is not significant.
• Leading Bytes is a set of bytes to be ignored while matching the leading bytes in the content.
• MIME type should be returned if the pattern matches.

Sample extra_types:

extra_types = ((b'test', b'\xff\xff\xff\xff', None, b'text/test'), ...)

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NOTE

Be careful while using the extra_types argument, as it may introduce some privilege escalation vulnerabilities for xtractmime. For more info, see here.

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Optional supported_types is a set of all MIME types supported the by user agent. If supported_types is not specified, all MIME types are assumed to be supported. Using this parameter can improve the performance of xtractmime.

function xtractmime.is_binary_data(input_bytes: bytes) -> bool

Return True if the provided byte sequence contains any binary data bytes, else False

MIME type group functions

The following functions return True if a given MIME type belongs to a certain MIME type group, or False otherwise:

xtractmime.mimegroups.is_archive_mime_type(mime_type: bytes) -> bool
xtractmime.mimegroups.is_audio_video_mime_type(mime_type: bytes) -> bool
xtractmime.mimegroups.is_font_mime_type(mime_type: bytes) -> bool
xtractmime.mimegroups.is_html_mime_type(mime_type: bytes) -> bool
xtractmime.mimegroups.is_image_mime_type(mime_type: bytes) -> bool
xtractmime.mimegroups.is_javascript_mime_type(mime_type: bytes) -> bool
xtractmime.mimegroups.is_json_mime_type(mime_type: bytes) -> bool
xtractmime.mimegroups.is_scriptable_mime_type(mime_type: bytes) -> bool
xtractmime.mimegroups.is_xml_mime_type(mime_type: bytes) -> bool
xtractmime.mimegroups.is_zip_mime_type(mime_type: bytes) -> bool

Example

>>> from xtractmime.mimegroups import is_html_mime_type, is_image_mime_type, is_zip_mime_type
>>> mime_type = b'text/html'
>>> is_html_mime_type(mime_type)
True
>>> is_image_mime_type(mime_type)
False
>>> is_zip_mime_type(mime_type)
False

Changelog

See the changelog