Determining the computed MIME type of a resource

xtractmime/__init__.py

@@ -1,5 +1,11 @@
 __version__ = "0.0.0"
 from typing import Optional, Set, Tuple
+from xtractmime._utils import (
+    is_archive,
+    is_audio_video,
+    is_font,
+    is_image,
+)
 
 _APACHE_TYPES = [
     b"text/plain",
@@ -39,6 +45,21 @@ def _is_match_mime_pattern(
     return True
 
 
+def _find_unknown_mimetype(input_bytes: bytes, sniff_scriptable: bool):
+    # TODO
+    pass
+
+
+def _sniff_mislabled_binary(input_bytes: bytes):
+    # TODO
+    pass
+
+
+def _compare_feed_html(input_bytes: bytes):
+    # TODO
+    pass
+
+
 def extract_mime(
     body: bytes,
     *,
@@ -48,8 +69,33 @@ def extract_mime(
     extra_types: Optional[Tuple[Tuple[bytes, bytes, Set[bytes], str], ...]] = None,
 ) -> str:
     extra_types = extra_types or tuple()
-    # supplied_type = content_types[-1] if content_types else None
+    supplied_type = content_types[-1] if content_types else None
+    check_for_apache = http_origin and supplied_type in _APACHE_TYPES
+    resource_header = memoryview(body) if len(body) < 1445 else memoryview(body)[:1445]
+
+    if supplied_type in (None, "unknown/unknown", "application/unknown", "*/*"):
+        _find_unknown_mimetype(body, not no_sniff)
+
+    if no_sniff:
+        return supplied_type
+
+    if check_for_apache:
+        return _sniff_mislabled_binary(body)
+
+    if supplied_type[-4:] is "+xml" or supplied_type in ("text/xml", "application/xml"):
+        return supplied_type
+
+    if supplied_type is "text/html":
+        return _compare_feed_html(body)
+
+    matched_type = is_image(resource_header)
+
+    if matched_type:
+        return matched_type
+
+    matched_type = is_audio_video(resource_header)
+
+    if matched_type:
+        return matched_type
 
-    # check_for_apache = http_origin and supplied_type in _APACHE_TYPES
-    # resource_header = memoryview(body) if len(body) < 1445 else memoryview(body)[:1445]
-    return "mimetype"
+    return supplied_type

xtractmime/_patterns.py

@@ -1,80 +1,40 @@
 #: Section 6.1, step 1
 #: https://mimesniff.spec.whatwg.org/commit-snapshots/609a3a3c935fbb805b46cf3d90768d695a1dcff2/#matching-an-image-type-pattern  # noqa: E501
 IMAGE_PATTERNS = (
-    (b"\x00\x00\x01\x00", b"\xff\xff\xff\xff", None, "image/x-icon"),  # A Windows Icon signature
-    (b"\x00\x00\x02\x00", b"\xff\xff\xff\xff", None, "image/x-icon"),  # A Windows Cursor signature
-    (b"BM", b"\xff\xff", None, "image/bmp"),  # The string "BM", a BMP signature
-    (
-        b"GIF87a",
-        b"\xff\xff\xff\xff\xff\xff",
-        None,
-        "image/gif",
-    ),  # The string "GIF87a", a GIF signature
-    (
-        b"GIF89a",
-        b"\xff\xff\xff\xff\xff\xff",
-        None,
-        "image/gif",
-    ),  # The string "GIF89a", a GIF signature
+    (b"\x00\x00\x01\x00", b"\xff\xff\xff\xff", None, "image/x-icon"),
+    (b"\x00\x00\x02\x00", b"\xff\xff\xff\xff", None, "image/x-icon"),
+    (b"BM", b"\xff\xff", None, "image/bmp"),
+    (b"GIF87a", b"\xff\xff\xff\xff\xff\xff", None, "image/gif",),
+    (b"GIF89a", b"\xff\xff\xff\xff\xff\xff", None, "image/gif",),
     (
         b"RIFF\x00\x00\x00\x00WEBPVP",
         b"\xff\xff\xff\xff\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff",
         None,
         "image/webp",
-    ),  # The string "RIFF" followed by four bytes followed by the string "WEBPVP"
-    # An error-checking byte followed by the string "PNG" followed by CR LF SUB LF,
-    # the PNG signature
+    ),
     (b"\x89PNG\r\n\x1a\n", b"\xff\xff\xff\xff\xff\xff\xff\xff", None, "image/png",),
-    (
-        b"\xff\xd8\xff",
-        b"\xff\xff\xff",
-        None,
-        "image/jpeg",
-    ),  # The JPEG Start of Image marker followed by the indicator byte of another marker
+    (b"\xff\xd8\xff", b"\xff\xff\xff", None, "image/jpeg",),
 )
 
 #: Section 6.2, step 1
 #: https://mimesniff.spec.whatwg.org/commit-snapshots/609a3a3c935fbb805b46cf3d90768d695a1dcff2/#matching-an-audio-or-video-type-pattern  # noqa: E501
 AUDIO_VIDEO_PATTERNS = (
-    (
-        b".snd",
-        b"\xff\xff\xff\xff",
-        None,
-        "audio/basic",
-    ),  # The string ".snd", the basic audio signature
-    # The string "FORM" followed by four bytes followed by the string "AIFF"
-    # the AIFF signature
+    (b".snd", b"\xff\xff\xff\xff", None, "audio/basic",),
     (
         b"FORM\x00\x00\x00\x00AIFF",
         b"\xff\xff\xff\xff\x00\x00\x00\x00\xff\xff\xff\xff",
         None,
         "audio/aiff",
     ),
-    (
-        b"ID3",
-        b"\xff\xff\xff",
-        None,
-        "audio/mpeg",
-    ),  # The string "ID3", the ID3v2-tagged MP3 signature
-    (
-        b"OggS\x00",
-        b"\xff\xff\xff\xff\xff",
-        None,
-        "application/ogg",
-    ),  # The string "OggS" followed by NUL, the Ogg container signature
-    # The string "MThd" followed by four bytes representing the number 6 in 32 bits
-    # (big-endian), the MIDI signature
+    (b"ID3", b"\xff\xff\xff", None, "audio/mpeg",),
+    (b"OggS\x00", b"\xff\xff\xff\xff\xff", None, "application/ogg",),
     (b"MThd\x00\x00\x00\x06", b"\xff\xff\xff\xff\xff\xff\xff\xff", None, "audio/midi",),
-    # The string "RIFF" followed by four bytes followed by the string "AVI "
-    # the AVI signature
     (
         b"RIFF\x00\x00\x00\x00AVI ",
         b"\xff\xff\xff\xff\x00\x00\x00\x00\xff\xff\xff\xff",
         None,
         "video/avi",
     ),
-    # The string "RIFF" followed by four bytes followed by the string "WAVE"
-    # the WAVE signature
     (
         b"RIFF\x00\x00\x00\x00WAVE",
         b"\xff\xff\xff\xff\x00\x00\x00\x00\xff\xff\xff\xff",
@@ -97,48 +57,24 @@
         ),
         None,
         "application/vnd.ms-fontobject",
-    ),  # 34 bytes followed by the string "LP", the Embedded OpenType signature
-    (
-        b"\x00\x01\x00\x00",
-        b"\xff\xff\xff\xff",
-        None,
-        "font/ttf",
-    ),  # 4 bytes representing the version number 1.0, a TrueType signature
-    (b"OTTO", b"\xff\xff\xff\xff", None, "font/otf"),  # The string "OTTO", the OpenType signature
-    (
-        b"ttcf",
-        b"\xff\xff\xff\xff",
-        None,
-        "font/collection",
-    ),  # The string "ttcf", the TrueType Collection signature
-    (
-        b"wOFF",
-        b"\xff\xff\xff\xff",
-        None,
-        "font/woff",
-    ),  # The string "wOFF", the Web Open Font Format 1.0 signature
-    (
-        b"wOF2",
-        b"\xff\xff\xff\xff",
-        None,
-        "font/woff2",
-    ),  # The string "wOF2", the Web Open Font Format 2.0 signature
+    ),
+    (b"\x00\x01\x00\x00", b"\xff\xff\xff\xff", None, "font/ttf",),
+    (b"OTTO", b"\xff\xff\xff\xff", None, "font/otf"),
+    (b"ttcf", b"\xff\xff\xff\xff", None, "font/collection",),
+    (b"wOFF", b"\xff\xff\xff\xff", None, "font/woff",),
+    (b"wOF2", b"\xff\xff\xff\xff", None, "font/woff2",),
 )
 
 #: Section 6.4, step 1
 #: https://mimesniff.spec.whatwg.org/commit-snapshots/609a3a3c935fbb805b46cf3d90768d695a1dcff2/#matching-an-archive-type-pattern  # noqa: E501
 ARCHIVE_PATTERNS = (
-    (b"\x1f\x8b\x08", b"\xff\xff\xff", None, "application/x-gzip"),  # The GZIP archive signature
-    (
-        b"PK\x03\x04",
-        b"\xff\xff\xff\xff",
-        None,
-        "application/zip",
-    ),  # The string "PK" followed by ETX EOT, the ZIP archive signature
-    (
-        b"Rar \x1a\x07\x00",
-        b"\xff\xff\xff\xff\xff\xff\xff",
-        None,
-        "application/x-rar-compressed",
-    ),  # The string "Rar " followed by SUB BEL NUL, the RAR archive signature
+    (b"\x1f\x8b\x08", b"\xff\xff\xff", None, "application/x-gzip"),
+    (b"PK\x03\x04", b"\xff\xff\xff\xff", None, "application/zip",),
+    (b"Rar \x1a\x07\x00", b"\xff\xff\xff\xff\xff\xff\xff", None, "application/x-rar-compressed",),
 )
+
+#: Section 7.1, step 1
+#: https://mimesniff.spec.whatwg.org/commit-snapshots/609a3a3c935fbb805b46cf3d90768d695a1dcff2/#identifying-a-resource-with-an-unknown-mime-type  # noqa: E501
+TEXT_PATTERNS = (
+
+    )