RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-07-26 17:37:35 +00:00
Code Issues Activity Actions

AK+Everywhere: Make Base64 decoding fallible

Browse source
This commit is contained in:
Ben Wiederhake 2021-10-23 15:43:59 +02:00 • committed by Linus Groh
parent 3bf1f7ae87
commit cb868cfa41
11 changed files with 73 additions and 32 deletions
Download patch file Download diff file Expand all files Collapse all files

39
AK/Base64.cpp
View file

@ -6,10 +6,7 @@
#include <AK/Array.h>
#include <AK/Base64.h>
#include <AK/ByteBuffer.h>
#include <AK/String.h>
#include <AK/StringBuilder.h>
#include <AK/StringView.h>
#include <AK/Types.h>
#include <AK/Vector.h>
@ -33,7 +30,8 @@ static constexpr auto make_alphabet()
static constexpr auto make_lookup_table()
{
constexpr auto alphabet = make_alphabet();
Array<u8, 256> table {};
Array<i16, 256> table;
table.fill(-1);
for (size_t i = 0; i < alphabet.size(); ++i) {
table[alphabet[i]] = i;
}
@ -50,19 +48,31 @@ size_t calculate_base64_encoded_length(ReadonlyBytes input)
return ((4 * input.size() / 3) + 3) & ~3;
}
ByteBuffer decode_base64(const StringView& input)
Optional<ByteBuffer> decode_base64(const StringView& input)
{
auto get = [&](const size_t offset, bool* is_padding = nullptr) -> u8 {
auto get = [&](const size_t offset, bool* is_padding) -> Optional<u8> {
constexpr auto table = make_lookup_table();
if (offset >= input.length())
return 0;
if (input[offset] == '=') {
if (is_padding)
*is_padding = true;
if (!is_padding)
return {};
*is_padding = true;
return 0;
}
return table[static_cast<unsigned char>(input[offset])];
i16 result = table[static_cast<unsigned char>(input[offset])];
if (result < 0)
return {};
VERIFY(result < 256);
return { result };
};
#define TRY_GET(index, is_padding) \
({ \
auto _temporary_result = get(index, is_padding); \
if (!_temporary_result.has_value()) \
return {}; \
_temporary_result.value(); \
})
Vector<u8> output;
output.ensure_capacity(calculate_base64_decoded_length(input));
@ -71,10 +81,10 @@ ByteBuffer decode_base64(const StringView& input)
bool in2_is_padding = false;
bool in3_is_padding = false;
const u8 in0 = get(i);
const u8 in1 = get(i + 1);
const u8 in2 = get(i + 2, &in2_is_padding);
const u8 in3 = get(i + 3, &in3_is_padding);
const u8 in0 = TRY_GET(i, nullptr);
const u8 in1 = TRY_GET(i + 1, nullptr);
const u8 in2 = TRY_GET(i + 2, &in2_is_padding);
const u8 in3 = TRY_GET(i + 3, &in3_is_padding);
const u8 out0 = (in0 << 2) | ((in1 >> 4) & 3);
const u8 out1 = ((in1 & 0xf) << 4) | ((in2 >> 2) & 0xf);
@ -87,8 +97,7 @@ ByteBuffer decode_base64(const StringView& input)
output.append(out2);
}
// FIXME: Handle OOM failure.
return ByteBuffer::copy(output).release_value();
return ByteBuffer::copy(output);
}
String encode_base64(ReadonlyBytes input)