amorfo77/json
1
0
Fork 0
mirror of https://github.com/nlohmann/json.git synced 2026-09-19 14:38:30 +00:00
Code Issues Packages Projects Releases Wiki Activity

🐛 reject ill-formed UTF-8 in CBOR/MessagePack/BSON text strings at decode time (#5531)

Browse Source 
from_cbor()/from_msgpack()/from_bson() copied the raw bytes of a decoded
text string into the resulting json value without any UTF-8 validation,
even though RFC 8949 §3.1 (CBOR) and the MessagePack/BSON specifications
all require text strings to be valid UTF-8. Malformed input only failed
later, if the value was dump()'d, with a type_error.316 - so the
allow_exceptions=false pattern used specifically to get a discarded
sentinel instead of an exception did not discard this category of
malformed input, unlike every other kind of malformed binary input this
library rejects at decode time (see #5529).

Fix this at the single choke point shared by BSON/CBOR/MessagePack/UBJSON
string reads, binary_reader::get_string(): validate the bytes with the
UTF-8 DFA right after they are read, and report failures the same way as
every other binary_reader error (parse_error.113), so allow_exceptions
and strict discarding behave consistently. get_binary()/binary blob reads
are untouched and still accept arbitrary bytes, since only text strings
are required to be UTF-8.

There were two independent implementations of a UTF-8 validator: the
lexer's streaming scanner, and the serializer's Hoehrmann DFA used by
dump_escaped_impl(). Rather than write a third, the serializer's decode()
function, its utf8d table and the UTF8_ACCEPT/UTF8_REJECT constants are
extracted into detail/string_utils.hpp (a low-level header already
included before both detail/input/ and detail/output/), alongside a new
is_valid_utf8() helper built on the same decode() step. serializer.hpp's
dump_escaped_impl() now calls the shared decode(), so there is exactly
one UTF-8 validator in the codebase; dump()'s exact type_error.316
messages and byte-index reporting are unchanged (see the added
regression-guard test in unit-serialization.cpp).



Claude-Session: https://claude.ai/code/session_01N4RQ1Ahan5YAGbnAQGjZTY

Signed-off-by: Niels Lohmann <niels.lohmann@gmail.com>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
This commit is contained in:
Niels Lohmann
2026-09-15 20:45:41 +02:00
committed by GitHub
co-authored by Claude Sonnet 5
parent 0886b7fe7e
commit 0c4f6c3034
11 changed files with 321 additions and 119 deletions
Download Patch File Download Diff File Expand all files Collapse all files
docs/mkdocs/docs/features/binary_formats/bson.md
+9
View File
@@ -109,6 +109,15 @@ The library maps BSON record types to JSON value types as follows:
If BSON input must be validated for strict specification compliance, validate it separately before passing it to
`from_bson()`.
!!! warning "UTF-8 validation of string values"
The BSON specification requires `string` values (type `0x02`) to be valid UTF-8. This library validates the
bytes of every such string at decode time and rejects ill-formed UTF-8 with a
[`parse_error.113`](../../home/exceptions.md#jsonexceptionparse_error113) exception (or, with `allow_exceptions`
set to `false`, a discarded value), rather than only failing later when the resulting value is dumped. Element
(key) names and `binary` values (type `0x05`) are unaffected and are never validated, since they are read
byte-by-byte as a C string, or are not required to hold text, respectively.
??? example
```cpp
docs/mkdocs/docs/features/binary_formats/cbor.md
+10
View File
@@ -176,6 +176,16 @@ The library maps CBOR types to JSON value types as follows:
CBOR allows map keys of any type, whereas JSON only allows strings as keys in object values. Therefore, CBOR maps with keys other than UTF-8 strings are rejected.
!!! warning "UTF-8 validation of text strings"
[RFC 8949, Section 3.1](https://www.rfc-editor.org/rfc/rfc8949.html#section-3.1) requires CBOR text strings
(major type 3) to be valid UTF-8. This library validates the bytes of every text string (object keys included) at
decode time and rejects ill-formed UTF-8 with a
[`parse_error.113`](../../home/exceptions.md#jsonexceptionparse_error113) exception (or, with
`allow_exceptions` set to `false`, a discarded value), rather than only failing later when the resulting value is
dumped. Byte strings (major type 2) are unaffected and are never validated, since they are not required to hold
text.
!!! warning "Tagged items"
Tagged items (0xC0..0xDB) will throw a parse error by default. They can be ignored by passing `cbor_tag_handler_t::ignore` to function `from_cbor`, in which case the tag is skipped and the enclosed data item is parsed on its own. They can be stored by passing `cbor_tag_handler_t::store` to function `from_cbor`. Note that no tag is ever interpreted: for instance, a text string tagged with tag 0 (date/time) stays a string.
docs/mkdocs/docs/features/binary_formats/messagepack.md
+8
View File
@@ -136,6 +136,14 @@ The library maps MessagePack types to JSON value types as follows:
Any MessagePack output created by `to_msgpack` can be successfully parsed by `from_msgpack`.
!!! warning "UTF-8 validation of string values"
The MessagePack specification requires `str` values (`fixstr`, `str 8`, `str 16`, `str 32`) to be valid UTF-8.
This library validates the bytes of every such string (object keys included) at decode time and rejects
ill-formed UTF-8 with a [`parse_error.113`](../../home/exceptions.md#jsonexceptionparse_error113) exception (or,
with `allow_exceptions` set to `false`, a discarded value), rather than only failing later when the resulting
value is dumped. `bin`/`ext`/`fixext` values are unaffected and are never validated, since they are not required
to hold text.
??? example
docs/mkdocs/docs/home/exceptions.md
+5 -1
View File
@@ -340,7 +340,8 @@ An unexpected byte was read in a [binary format](../features/binary_formats/inde
### json.exception.parse_error.113
A string could not be read from a [binary format](../features/binary_formats/index.md): either a value that is not a
string was read where one was required (for instance as a map key), or the string's length specification is invalid.
string was read where one was required (for instance as a map key), the string's length specification is invalid, or
the string's bytes are not valid UTF-8.
!!! failure "Example messages"
@@ -356,6 +357,9 @@ string was read where one was required (for instance as a map key), or the strin
```
[json.exception.parse_error.113] parse error at byte 3: syntax error while parsing BJData string: string length must not be negative
```
```
[json.exception.parse_error.113] parse error at byte 3: syntax error while parsing CBOR string: invalid string: ill-formed UTF-8 byte
```
### json.exception.parse_error.114
include/nlohmann/detail/input/binary_reader.hpp
+19 -1
View File
@@ -32,6 +32,7 @@
#include <nlohmann/detail/meta/is_sax.hpp>
#include <nlohmann/detail/meta/type_traits.hpp>
#include <nlohmann/detail/string_concat.hpp>
#include <nlohmann/detail/string_utils.hpp>
#include <nlohmann/detail/value_t.hpp>
NLOHMANN_JSON_NAMESPACE_BEGIN
@@ -3313,7 +3314,24 @@ class binary_reader
const NumberType len,
string_t& result)
{
return get_bytes(format, len, "string", result);
if (JSON_HEDLEY_UNLIKELY(!get_bytes(format, len, "string", result)))
{
return false;
}
// RFC 8949 (CBOR) §3.1 and the MessagePack/BSON/UBJSON specifications
// all require text strings to be valid UTF-8; reject anything else
// right here so malformed input is caught at decode time instead of
// only surfacing later as a type_error.316 when the value is dumped
// (which would defeat allow_exceptions=false / strict discarding).
if (JSON_HEDLEY_UNLIKELY(!is_valid_utf8(result)))
{
return sax->parse_error(chars_read, get_token_string(),
parse_error::create(113, chars_read,
exception_message(format, "invalid string: ill-formed UTF-8 byte", "string"), nullptr));
}
return true;
}
/*!
include/nlohmann/detail/output/serializer.hpp
+1 -58
View File
@@ -31,6 +31,7 @@
#include <nlohmann/detail/output/binary_writer.hpp>
#include <nlohmann/detail/output/output_adapters.hpp>
#include <nlohmann/detail/string_concat.hpp>
#include <nlohmann/detail/string_utils.hpp>
#include <nlohmann/detail/value_t.hpp>
NLOHMANN_JSON_NAMESPACE_BEGIN
@@ -57,8 +58,6 @@ class serializer
using number_integer_t = typename BasicJsonType::number_integer_t;
using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
using binary_char_t = typename BasicJsonType::binary_t::value_type;
static constexpr std::uint8_t UTF8_ACCEPT = 0;
static constexpr std::uint8_t UTF8_REJECT = 1;
public:
/*!
@@ -1584,62 +1583,6 @@ class serializer
}
}
/*!
@brief check whether a string is UTF-8 encoded
The function checks each byte of a string whether it is UTF-8 encoded. The
result of the check is stored in the @a state parameter. The function must
be called initially with state 0 (accept). State 1 means the string must
be rejected, because the current byte is not allowed. If the string is
completely processed, but the state is non-zero, the string ended
prematurely; that is, the last byte indicated more bytes should have
followed.
@param[in,out] state the state of the decoding
@param[in,out] codep codepoint (valid only if resulting state is UTF8_ACCEPT)
@param[in] byte next byte to decode
@return new state
@note The function has been edited: a std::array is used.
@copyright Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
@sa http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
*/
static std::uint8_t decode(std::uint8_t& state, std::uint32_t& codep, const std::uint8_t byte) noexcept
{
static const std::array<std::uint8_t, 400> utf8d =
{
{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 00..1F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20..3F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 40..5F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 60..7F
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, // 80..9F
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // A0..BF
8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // C0..DF
0xA, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x4, 0x3, 0x3, // E0..EF
0xB, 0x6, 0x6, 0x6, 0x5, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, // F0..FF
0x0, 0x1, 0x2, 0x3, 0x5, 0x8, 0x7, 0x1, 0x1, 0x1, 0x4, 0x6, 0x1, 0x1, 0x1, 0x1, // s0..s0
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, // s1..s2
1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, // s3..s4
1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, // s5..s6
1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 // s7..s8
}
};
JSON_ASSERT(static_cast<std::size_t>(byte) < utf8d.size());
const std::uint8_t type = utf8d[byte];
codep = (state != UTF8_ACCEPT)
? (byte & 0x3fu) | (codep << 6u)
: (0xFFu >> type) & (byte);
const std::size_t index = 256u + (static_cast<size_t>(state) * 16u) + static_cast<size_t>(type);
JSON_ASSERT(index < utf8d.size());
state = utf8d[index];
return state;
}
/*
* Overload to make the compiler happy while it is instantiating
* dump_integer for number_unsigned_t.
include/nlohmann/detail/string_utils.hpp
+97
View File
@@ -8,10 +8,13 @@
#pragma once
#include <array> // array
#include <cstddef> // size_t
#include <cstdint> // uint8_t, uint32_t
#include <string> // string, to_string
#include <nlohmann/detail/abi_macros.hpp>
#include <nlohmann/detail/macro_scope.hpp>
NLOHMANN_JSON_NAMESPACE_BEGIN
namespace detail
@@ -33,5 +36,99 @@ StringType to_string(std::size_t value)
return result;
}
///////////////////
// UTF-8 decoding //
///////////////////
// UTF-8 decoder states used by decode() below
static constexpr std::uint8_t UTF8_ACCEPT = 0;
static constexpr std::uint8_t UTF8_REJECT = 1;
/*!
@brief process a byte of a UTF-8 sequence
This is a single-byte step of a "shift-based" UTF-8 decoder originally
written by Björn Hoehrmann. See
http://bjoern.hoehrmann.de/utf-8/decoder/dfa/ for details.
This decoder is the single source of truth for UTF-8 validation in this
library: it is used both by the serializer (to escape and, in strict mode,
reject ill-formed UTF-8 when dumping a string) and by the binary readers
(to reject ill-formed UTF-8 in CBOR/MessagePack/BSON/UBJSON text strings at
decode time; see @ref is_valid_utf8 below).
@param[in,out] state the current decoder state
@param[in,out] codep codepoint (valid only if resulting state is UTF8_ACCEPT)
@param[in] byte next byte to decode
@return new state
@note Original source: http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
@sa http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
*/
inline std::uint8_t decode(std::uint8_t& state, std::uint32_t& codep, const std::uint8_t byte) noexcept
{
static const std::array<std::uint8_t, 400> utf8d =
{
{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 00..1F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20..3F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 40..5F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 60..7F
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, // 80..9F
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // A0..BF
8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // C0..DF
0xA, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x4, 0x3, 0x3, // E0..EF
0xB, 0x6, 0x6, 0x6, 0x5, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, // F0..FF
0x0, 0x1, 0x2, 0x3, 0x5, 0x8, 0x7, 0x1, 0x1, 0x1, 0x4, 0x6, 0x1, 0x1, 0x1, 0x1, // s0..s0
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, // s1..s2
1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, // s3..s4
1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, // s5..s6
1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 // s7..s8
}
};
JSON_ASSERT(static_cast<std::size_t>(byte) < utf8d.size());
const std::uint8_t type = utf8d[byte];
codep = (state != UTF8_ACCEPT)
? (byte & 0x3fu) | (codep << 6u)
: (0xFFu >> type) & (byte);
const std::size_t index = 256u + (static_cast<std::size_t>(state) * 16u) + static_cast<std::size_t>(type);
JSON_ASSERT(index < utf8d.size());
state = utf8d[index];
return state;
}
/*!
@brief check whether a string consists solely of valid UTF-8
Used by the CBOR/MessagePack/BSON/UBJSON binary readers to reject text
strings that are not valid UTF-8 at decode time (RFC 8949 §3.1 and the
MessagePack/BSON specifications all require text strings to be UTF-8), so
that malformed input is caught immediately instead of only surfacing later
as a type_error.316 when the resulting value is dumped.
@param[in] s the string to check
@return whether @a s is valid UTF-8
*/
template<typename StringType>
inline bool is_valid_utf8(const StringType& s) noexcept
{
std::uint8_t state = UTF8_ACCEPT;
std::uint32_t codepoint = 0;
for (std::size_t i = 0; i < s.size(); ++i)
{
decode(state, codepoint, static_cast<std::uint8_t>(s[i]));
if (state == UTF8_REJECT)
{
return false;
}
}
return state == UTF8_ACCEPT;
}
} // namespace detail
NLOHMANN_JSON_NAMESPACE_END
single_include/nlohmann/json.hpp
+120 -59
View File
@@ -6002,11 +6002,15 @@ NLOHMANN_JSON_NAMESPACE_END
#include <array> // array
#include <cstddef> // size_t
#include <cstdint> // uint8_t, uint32_t
#include <string> // string, to_string
// #include <nlohmann/detail/abi_macros.hpp>
// #include <nlohmann/detail/macro_scope.hpp>
NLOHMANN_JSON_NAMESPACE_BEGIN
namespace detail
@@ -6028,6 +6032,100 @@ StringType to_string(std::size_t value)
return result;
}
///////////////////
// UTF-8 decoding //
///////////////////
// UTF-8 decoder states used by decode() below
static constexpr std::uint8_t UTF8_ACCEPT = 0;
static constexpr std::uint8_t UTF8_REJECT = 1;
/*!
@brief process a byte of a UTF-8 sequence
This is a single-byte step of a "shift-based" UTF-8 decoder originally
written by Björn Hoehrmann. See
http://bjoern.hoehrmann.de/utf-8/decoder/dfa/ for details.
This decoder is the single source of truth for UTF-8 validation in this
library: it is used both by the serializer (to escape and, in strict mode,
reject ill-formed UTF-8 when dumping a string) and by the binary readers
(to reject ill-formed UTF-8 in CBOR/MessagePack/BSON/UBJSON text strings at
decode time; see @ref is_valid_utf8 below).
@param[in,out] state the current decoder state
@param[in,out] codep codepoint (valid only if resulting state is UTF8_ACCEPT)
@param[in] byte next byte to decode
@return new state
@note Original source: http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
@sa http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
*/
inline std::uint8_t decode(std::uint8_t& state, std::uint32_t& codep, const std::uint8_t byte) noexcept
{
static const std::array<std::uint8_t, 400> utf8d =
{
{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 00..1F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20..3F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 40..5F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 60..7F
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, // 80..9F
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // A0..BF
8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // C0..DF
0xA, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x4, 0x3, 0x3, // E0..EF
0xB, 0x6, 0x6, 0x6, 0x5, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, // F0..FF
0x0, 0x1, 0x2, 0x3, 0x5, 0x8, 0x7, 0x1, 0x1, 0x1, 0x4, 0x6, 0x1, 0x1, 0x1, 0x1, // s0..s0
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, // s1..s2
1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, // s3..s4
1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, // s5..s6
1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 // s7..s8
}
};
JSON_ASSERT(static_cast<std::size_t>(byte) < utf8d.size());
const std::uint8_t type = utf8d[byte];
codep = (state != UTF8_ACCEPT)
? (byte & 0x3fu) | (codep << 6u)
: (0xFFu >> type) & (byte);
const std::size_t index = 256u + (static_cast<std::size_t>(state) * 16u) + static_cast<std::size_t>(type);
JSON_ASSERT(index < utf8d.size());
state = utf8d[index];
return state;
}
/*!
@brief check whether a string consists solely of valid UTF-8
Used by the CBOR/MessagePack/BSON/UBJSON binary readers to reject text
strings that are not valid UTF-8 at decode time (RFC 8949 §3.1 and the
MessagePack/BSON specifications all require text strings to be UTF-8), so
that malformed input is caught immediately instead of only surfacing later
as a type_error.316 when the resulting value is dumped.
@param[in] s the string to check
@return whether @a s is valid UTF-8
*/
template<typename StringType>
inline bool is_valid_utf8(const StringType& s) noexcept
{
std::uint8_t state = UTF8_ACCEPT;
std::uint32_t codepoint = 0;
for (std::size_t i = 0; i < s.size(); ++i)
{
decode(state, codepoint, static_cast<std::uint8_t>(s[i]));
if (state == UTF8_REJECT)
{
return false;
}
}
return state == UTF8_ACCEPT;
}
} // namespace detail
NLOHMANN_JSON_NAMESPACE_END
@@ -12016,6 +12114,8 @@ NLOHMANN_JSON_NAMESPACE_END
// #include <nlohmann/detail/string_concat.hpp>
// #include <nlohmann/detail/string_utils.hpp>
// #include <nlohmann/detail/value_t.hpp>
@@ -15298,7 +15398,24 @@ class binary_reader
const NumberType len,
string_t& result)
{
return get_bytes(format, len, "string", result);
if (JSON_HEDLEY_UNLIKELY(!get_bytes(format, len, "string", result)))
{
return false;
}
// RFC 8949 (CBOR) §3.1 and the MessagePack/BSON/UBJSON specifications
// all require text strings to be valid UTF-8; reject anything else
// right here so malformed input is caught at decode time instead of
// only surfacing later as a type_error.316 when the value is dumped
// (which would defeat allow_exceptions=false / strict discarding).
if (JSON_HEDLEY_UNLIKELY(!is_valid_utf8(result)))
{
return sax->parse_error(chars_read, get_token_string(),
parse_error::create(113, chars_read,
exception_message(format, "invalid string: ill-formed UTF-8 byte", "string"), nullptr));
}
return true;
}
/*!
@@ -21763,6 +21880,8 @@ NLOHMANN_JSON_NAMESPACE_END
// #include <nlohmann/detail/string_concat.hpp>
// #include <nlohmann/detail/string_utils.hpp>
// #include <nlohmann/detail/value_t.hpp>
@@ -21790,8 +21909,6 @@ class serializer
using number_integer_t = typename BasicJsonType::number_integer_t;
using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
using binary_char_t = typename BasicJsonType::binary_t::value_type;
static constexpr std::uint8_t UTF8_ACCEPT = 0;
static constexpr std::uint8_t UTF8_REJECT = 1;
public:
/*!
@@ -23317,62 +23434,6 @@ class serializer
}
}
/*!
@brief check whether a string is UTF-8 encoded
The function checks each byte of a string whether it is UTF-8 encoded. The
result of the check is stored in the @a state parameter. The function must
be called initially with state 0 (accept). State 1 means the string must
be rejected, because the current byte is not allowed. If the string is
completely processed, but the state is non-zero, the string ended
prematurely; that is, the last byte indicated more bytes should have
followed.
@param[in,out] state the state of the decoding
@param[in,out] codep codepoint (valid only if resulting state is UTF8_ACCEPT)
@param[in] byte next byte to decode
@return new state
@note The function has been edited: a std::array is used.
@copyright Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
@sa http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
*/
static std::uint8_t decode(std::uint8_t& state, std::uint32_t& codep, const std::uint8_t byte) noexcept
{
static const std::array<std::uint8_t, 400> utf8d =
{
{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 00..1F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20..3F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 40..5F
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 60..7F
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, // 80..9F
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // A0..BF
8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // C0..DF
0xA, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x4, 0x3, 0x3, // E0..EF
0xB, 0x6, 0x6, 0x6, 0x5, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, // F0..FF
0x0, 0x1, 0x2, 0x3, 0x5, 0x8, 0x7, 0x1, 0x1, 0x1, 0x4, 0x6, 0x1, 0x1, 0x1, 0x1, // s0..s0
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, // s1..s2
1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, // s3..s4
1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, // s5..s6
1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 // s7..s8
}
};
JSON_ASSERT(static_cast<std::size_t>(byte) < utf8d.size());
const std::uint8_t type = utf8d[byte];
codep = (state != UTF8_ACCEPT)
? (byte & 0x3fu) | (codep << 6u)
: (0xFFu >> type) & (byte);
const std::size_t index = 256u + (static_cast<size_t>(state) * 16u) + static_cast<size_t>(type);
JSON_ASSERT(index < utf8d.size());
state = utf8d[index];
return state;
}
/*
* Overload to make the compiler happy while it is instantiating
* dump_integer for number_unsigned_t.
tests/src/unit-cbor.cpp
+21
View File
@@ -1833,6 +1833,27 @@ TEST_CASE("CBOR")
CHECK(json::from_cbor(std::vector<uint8_t>({0xa1, 0xff, 0x01}), true, false).is_discarded());
}
SECTION("invalid UTF-8 in string (see #5529)")
{
// a two-character text string (major type 3) whose bytes are not
// valid UTF-8 (0xC0 0xAE is an overlong encoding of '.') must be
// rejected at decode time, matching every other kind of
// malformed binary input, rather than only failing later when
// the resulting value is dumped
json _;
CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<uint8_t>({0x62, 0xc0, 0xae})), "[json.exception.parse_error.113] parse error at byte 3: syntax error while parsing CBOR string: invalid string: ill-formed UTF-8 byte", json::parse_error&);
CHECK(json::from_cbor(std::vector<uint8_t>({0x62, 0xc0, 0xae}), true, false).is_discarded());
// a CBOR byte string (major type 2) with the very same bytes is
// NOT text and must still be accepted as-is
CHECK_NOTHROW(_ = json::from_cbor(std::vector<uint8_t>({0x42, 0xc0, 0xae})));
CHECK(_ == json::binary(std::vector<std::uint8_t>({0xc0, 0xae})));
// valid UTF-8 must still round-trip
const json j = "h\xc3\xa9llo, w\xc3\xb6rld! \xe6\x97\xa5\xe6\x9c\xac\xe8\xaa\x9e"; // héllo, wörld! 日本語
CHECK(json::from_cbor(json::to_cbor(j)) == j);
}
SECTION("strict mode")
{
std::vector<uint8_t> const vec = {0xf6, 0xf6};
tests/src/unit-msgpack.cpp
+21
View File
@@ -1554,6 +1554,27 @@ TEST_CASE("MessagePack")
CHECK(json::from_msgpack(std::vector<uint8_t>({0x81, 0xff, 0x01}), true, false).is_discarded());
}
SECTION("invalid UTF-8 in string (see #5529)")
{
// a fixstr of length 2 (0xA0 | 2) whose bytes are not valid UTF-8
// (0xC0 0xAE is an overlong encoding of '.') must be rejected at
// decode time, matching every other kind of malformed binary
// input, rather than only failing later when the resulting
// value is dumped
json _;
CHECK_THROWS_WITH_AS(_ = json::from_msgpack(std::vector<uint8_t>({0xa2, 0xc0, 0xae})), "[json.exception.parse_error.113] parse error at byte 3: syntax error while parsing MessagePack string: invalid string: ill-formed UTF-8 byte", json::parse_error&);
CHECK(json::from_msgpack(std::vector<uint8_t>({0xa2, 0xc0, 0xae}), true, false).is_discarded());
// a MessagePack bin8 blob with the very same bytes is NOT text
// and must still be accepted as-is
CHECK_NOTHROW(_ = json::from_msgpack(std::vector<uint8_t>({0xc4, 0x02, 0xc0, 0xae})));
CHECK(_ == json::binary(std::vector<std::uint8_t>({0xc0, 0xae})));
// valid UTF-8 must still round-trip
const json j = "h\xc3\xa9llo, w\xc3\xb6rld! \xe6\x97\xa5\xe6\x9c\xac\xe8\xaa\x9e"; // héllo, wörld! 日本語
CHECK(json::from_msgpack(json::to_msgpack(j)) == j);
}
SECTION("strict mode")
{
std::vector<uint8_t> const vec = {0xc0, 0xc0};
tests/src/unit-serialization.cpp
+10
View File
@@ -94,6 +94,16 @@ TEST_CASE("serialization")
CHECK(j.dump(-1, ' ', true, json::error_handler_t::replace) == "\"\\u00e4\\ufffd\\u00fc\"");
}
SECTION("invalid character (regression guard for shared UTF-8 decoder, see #5529)")
{
// dump_escaped_impl() now calls the UTF-8 decoder shared with the
// binary readers (detail::decode() in string_utils.hpp) instead
// of a private copy; the exact type_error.316 message/behavior
// must stay byte-for-byte the same as before that extraction
const json j = "ä\xA9ü";
CHECK_THROWS_WITH_AS(utils::ignore_return_value(j.dump()), "[json.exception.type_error.316] invalid UTF-8 byte at index 2: 0xA9", json::type_error&);
}
SECTION("ending with incomplete character")
{
const json j = "123\xC2";