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Niels Lohmann
b2760f273d
The header comment of six of the seven binary-format fuzzer drivers listed an invariant the code does not check: CBOR, MessagePack, BSON and BON8 said "assert(j1 == j2)", but the code checks byte stability, assert(to_X(j2) == vec). UBJSON and BJData still described the old "assert(j1 == j2/j3/j4)" byte-exact check from before PR #5494 replaced it with a use_size/use_type-aware round trip (UBJSON) and a value-stability check (BJData); BJData's added paragraph already explained the new check, but the step list above it did not. Also remove a dead branch in fuzzer-parse_bson.cpp: from_bson() is called with allow_exceptions = true, so it throws instead of returning a discarded value, and the "if (j1.is_discarded()) return 0;" guard could never trigger. Drop the unused <iostream> include from all seven drivers and <sstream> from all but fuzzer-parse_bon8.cpp, which is the only one that uses std::istringstream. Overlaps #5601, which edits all seven drivers in the same hunks. Closes #5714 item 4. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
74 lines
2.0 KiB
C++
74 lines
2.0 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_bson(data)
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- vec = to_bson(j1)
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- j2 = from_bson(vec)
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- assert(to_bson(j2) == vec)
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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 <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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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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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_bson(vec1);
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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_bson(j1);
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// parse serialization
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json const j2 = json::from_bson(vec2);
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// serializations must match
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assert(json::to_bson(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 BSON 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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}
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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 can occur during parsing, too
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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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