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LibWeb/MimeSniff: Implement MP4 signature matching

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This commit is contained in:
Kemal Zebari 2024-01-08 01:36:33 -08:00 • committed by Andrew Kaster
parent 90ff6cca8a
commit 3aaa1c1df7
2 changed files with 86 additions and 3 deletions
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35
Tests/LibWeb/TestMimeSniff.cpp
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2023, Kemal Zebari <kemalzebra@gmail.com>.
* Copyright (c) 2023-2024, Kemal Zebari <kemalzebra@gmail.com>.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -247,6 +247,39 @@ TEST_CASE(determine_computed_mime_type_in_audio_or_video_sniffing_context)
EXPECT_EQ(mime_type, computed_mime_type.essence());
}
TEST_CASE(determine_computed_mime_type_when_trying_to_match_mp4_signature)
{
HashMap<StringView, Vector<StringView>> mime_type_to_headers_map;
mime_type_to_headers_map.set("application/octet-stream"sv, {
// Payload length < 12.
"!= 12"sv,
// Payload length < box size.
"\x00\x00\x00\x1F\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A"sv,
// Box size % 4 != 0.
"\x00\x00\x00\x0D\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"sv,
// 4 bytes after box size header != "ftyp".
"\x00\x00\x00\x0C\x00\x00\x00\x00\x00\x00\x00\x00"sv,
// Sequence "mp4" couldn't be found in ftyp box.
"\x00\x00\x00\x18\x66\x74\x79\x70isom\x00\x00\x00\x00\x61\x76\x63\x31\x00\x00\x00\x00"sv,
});
mime_type_to_headers_map.set("video/mp4"sv, {
// 3 bytes after "ftyp" sequence == "mp4".
"\x00\x00\x00\x0C\x66\x74\x79\x70mp42"sv,
// "mp4" sequence found while executing while loop (this input covers entire loop)
"\x00\x00\x00\x18\x66\x74\x79\x70isom\x00\x00\x00\x00\x61\x76\x63\x31mp41"sv,
});
for (auto const& mime_type_to_headers : mime_type_to_headers_map) {
auto mime_type = mime_type_to_headers.key;
for (auto const& header : mime_type_to_headers.value) {
auto computed_mime_type = MUST(Web::MimeSniff::Resource::sniff(header.bytes(), Web::MimeSniff::SniffingConfiguration { .sniffing_context = Web::MimeSniff::SniffingContext::AudioOrVideo }));
EXPECT_EQ(mime_type, MUST(computed_mime_type.serialized()));
}
}
}
TEST_CASE(determine_computed_mime_type_in_a_font_context)
{
// Cover case where supplied type is an XML MIME type.

54
Userland/Libraries/LibWeb/MimeSniff/Resource.cpp
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2023, Kemal Zebari <kemalzebra@gmail.com>.
* Copyright (c) 2023-2024, Kemal Zebari <kemalzebra@gmail.com>.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -136,6 +136,53 @@ ErrorOr<Optional<MimeType>> match_an_image_type_pattern(ReadonlyBytes input)
return OptionalNone {};
}
// https://mimesniff.spec.whatwg.org/#signature-for-mp4
bool matches_mp4_signature(ReadonlyBytes sequence)
{
// 1. Let sequence be the byte sequence to be matched, where sequence[s] is byte s in sequence and sequence[0] is the first byte in sequence.
// 2. Let length be the number of bytes in sequence.
auto length = sequence.size();
// 3. If length is less than 12, return false.
if (length < 12)
return false;
// 4. Let box-size be the four bytes from sequence[0] to sequence[3], interpreted as a 32-bit unsigned big-endian integer.
u32 box_size = 0;
box_size |= static_cast<u32>(sequence[0] << 24);
box_size |= box_size + static_cast<u32>(sequence[1] << 16);
box_size |= box_size + static_cast<u32>(sequence[2] << 8);
box_size |= box_size + sequence[3];
// 5. If length is less than box-size or if box-size modulo 4 is not equal to 0, return false.
if ((length < box_size) || (box_size % 4 != 0))
return false;
// 6. If the four bytes from sequence[4] to sequence[7] are not equal to 0x66 0x74 0x79 0x70 ("ftyp"), return false.
if (sequence.slice(4, 4) != "\x66\x74\x79\x70"sv.bytes())
return false;
// 7. If the three bytes from sequence[8] to sequence[10] are equal to 0x6D 0x70 0x34 ("mp4"), return true.
if (sequence.slice(8, 3) == "\x6D\x70\x34"sv.bytes())
return true;
// 8. Let bytes-read be 16.
u32 bytes_read = 16;
// 9. While bytes-read is less than box-size, continuously loop through these steps:
// 1. If the three bytes from sequence[bytes-read] to sequence[bytes-read + 2] are equal to 0x6D 0x70 0x34 ("mp4"), return true.
// 2. Increment bytes-read by 4.
while (bytes_read < box_size) {
if (sequence.slice(bytes_read, 3) == "\x6D\x70\x34"sv.bytes())
return true;
bytes_read += 4;
}
// 10. Return false.
return false;
}
// https://mimesniff.spec.whatwg.org/#matching-an-audio-or-video-type-pattern
ErrorOr<Optional<MimeType>> match_an_audio_or_video_type_pattern(ReadonlyBytes input)
{
@ -174,7 +221,10 @@ ErrorOr<Optional<MimeType>> match_an_audio_or_video_type_pattern(ReadonlyBytes i
return MimeType::parse(row.mime_type);
}
// FIXME: 2. If input matches the signature for MP4, return "video/mp4".
// 2. If input matches the signature for MP4, return "video/mp4".
if (matches_mp4_signature(input))
return MimeType::create("video"_string, "mp4"_string);
// FIXME: 3. If input matches the signature for WebM, return "video/webm".
// FIXME: 4. If input matches the signature for MP3 without ID3, return "audio/mpeg".