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https://github.com/nlohmann/json.git
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Niels Lohmann
437a95cfdb
When the SAX parser asks to recover, the binary readers now repair an item whose end is known and read on after it, as RFC 8949, Section 5.3 describes for CBOR: - CBOR: tags are ignored, and simple values other than false, true, and null become null (RFC 8949, Section 6.1); a negative integer below the range of number_integer_t becomes the nearest floating-point number. - Strings that are not valid UTF-8 get U+FFFD for each ill-formed sequence, as in JSON text; so does a UBJSON/BJData char above 0x7F. - UBJSON/BJData high-precision numbers keep their longest valid beginning (via the lexer's recover_token()), or become infinity. - Members whose key is not a string are skipped (CBOR, MessagePack, BON8), like members without a key in JSON text. - BSON elements of types the library does not read (ObjectId, datetime, decimal128, ...) become null; a string without its terminator and a document whose size does not match are kept. Where the end of an item is unknown, reading stops as before, except that BSON skips to the end of the document, whose size it knows. The value read before such an error is now completed by the reader from its container stack, as the JSON parser does, instead of by a proxy SAX parser, which is removed. Like the parser, binary_reader gets an AllowRecovery template parameter, so that from_*() compile without the new code. Tests: a table of repairs, numbers out of range, errors that stop, and a sweep over changed and removed bytes of eight encodings that checks balanced events and that the first error is the one from_*() reports. All fuzzers now run a recovering checker; the binary ones also check that it reports an error exactly when from_*() fails. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
88 lines
2.6 KiB
C++
88 lines
2.6 KiB
C++
// __ _____ _____ _____
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// __| | __| | | | JSON for Modern C++ (supporting code)
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// | | |__ | | | | | | version 3.12.0
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// |_____|_____|_____|_|___| https://github.com/nlohmann/json
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//
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// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
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// SPDX-License-Identifier: MIT
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/*
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This file implements a parser test suitable for fuzz testing. Given a byte
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array data, it performs the following steps:
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- j1 = from_msgpack(data)
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- vec = to_msgpack(j1)
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- j2 = from_msgpack(vec)
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- assert(j1 == j2)
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Furthermore, it reads data with a SAX parser that recovers from every error
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and checks that the events are balanced, that reading ends, and that it
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reports an error exactly when from_msgpack() fails (see #3989).
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The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
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drivers.
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*/
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#include <cassert>
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#include <iostream>
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#include <sstream>
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#include <nlohmann/json.hpp>
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// the round-trip checks below are assertions; NDEBUG would compile them away
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#ifdef NDEBUG
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#error "the fuzzer drivers must be built without NDEBUG"
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#endif
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#include "fuzzer-recovering_checker.hpp"
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using json = nlohmann::json;
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// see http://llvm.org/docs/LibFuzzer.html
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extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
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{
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// step 0: recover from all errors, reading from memory and from a stream
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const bool recovered_without_errors = check_recovering_parse(data, size, json::input_format_t::msgpack).errors == 0;
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try
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{
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// step 1: parse input
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std::vector<uint8_t> const vec1(data, data + size);
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json const j1 = json::from_msgpack(vec1);
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assert(recovered_without_errors);
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try
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{
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// step 2: round trip
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std::vector<uint8_t> const vec2 = json::to_msgpack(j1);
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// parse serialization
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json const j2 = json::from_msgpack(vec2);
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// serializations must match
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assert(json::to_msgpack(j2) == vec2);
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}
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catch (const json::parse_error&)
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{
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// parsing a MessagePack serialization must not fail
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assert(false);
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}
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}
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catch (const json::parse_error&)
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{
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// parse errors are ok, because input may be random bytes
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assert(!recovered_without_errors);
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}
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catch (const json::type_error&)
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{
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// type errors can occur during parsing, too
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}
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catch (const json::out_of_range&)
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{
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// out of range errors may happen if provided sizes are excessive
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assert(!recovered_without_errors);
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}
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// return 0 - non-zero return values are reserved for future use
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return 0;
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}
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