mirror of
https://github.com/ElementsProject/lightning.git
synced 2024-11-20 02:27:51 +01:00
70 lines
2.5 KiB
Markdown
70 lines
2.5 KiB
Markdown
# Fuzz testing
|
|
|
|
C-lightning currently supports coverage-guided fuzz testing using [LLVM's libfuzzer](https://www.llvm.org/docs/LibFuzzer.html)
|
|
when built with `clang`.
|
|
|
|
The goal of fuzzing is to generate mutated -and often unexpected- inputs (`seed`s) to pass
|
|
to (parts of) a program (`target`) in order to make sure the codepaths used:
|
|
- do not crash
|
|
- are valid (if combined with sanitizers)
|
|
The generated seeds can be stored and form a `corpus`, which we try to optimise (don't
|
|
store two seeds that lead to the same codepath).
|
|
|
|
For more info about fuzzing see [here](https://github.com/google/fuzzing/tree/master/docs),
|
|
and for more about `libfuzzer` in particular see [here](https://www.llvm.org/docs/LibFuzzer.html).
|
|
|
|
|
|
## Build the fuzz targets
|
|
|
|
In order to build the C-lightning binaries with code coverage you will need a recent
|
|
[clang](http://clang.llvm.org/). The more recent the compiler version the better.
|
|
|
|
Then you'll need to enable support at configuration time. You likely want to enable
|
|
a few sanitizers for bug detections as well as experimental features for an extended
|
|
coverage (not required though).
|
|
|
|
```
|
|
DEVELOPER=1 EXPERIMENTAL_FEATURES=1 ASAN=1 UBSAN=1 VALGRIND=0 FUZZING=1 CC=clang ./configure && make
|
|
```
|
|
|
|
The targets will be built in `tests/fuzz/` as `fuzz-` binaries.
|
|
|
|
|
|
## Run one or more target(s)
|
|
|
|
You can run each target independently. Pass `-help=1` to see available options, for
|
|
example:
|
|
```
|
|
./tests/fuzz/fuzz-addr -help=1
|
|
```
|
|
|
|
Otherwise, you can use the Python runner to either run the targets against a given seed
|
|
corpus:
|
|
```
|
|
./tests/fuzz/run.py fuzz_corpus -j2
|
|
```
|
|
Or extend this corpus:
|
|
```
|
|
./tests/fuzz/run.py fuzz_corpus -j2 --generate --runs 12345
|
|
```
|
|
|
|
The latter will run all targets two by two `12345` times.
|
|
|
|
If you want to contribute new seeds, be sure to merge your corpus with the main one:
|
|
```
|
|
./tests/fuzz/run.py my_locally_extended_fuzz_corpus -j2 --generate --runs 12345
|
|
./tests/fuzz/run.py main_fuzz_corpus --merge_dir my_locally_extended_fuzz_corpus
|
|
```
|
|
|
|
|
|
## Write new fuzzing targets
|
|
|
|
In order to write a new target:
|
|
- include the `libfuzz.h` header
|
|
- fill two functions: `init()` for static stuff and `run()` which will be called
|
|
repeatedly with mutated data.
|
|
- read about [what makes a good fuzz target](https://github.com/google/fuzzing/blob/master/docs/good-fuzz-target.md).
|
|
|
|
A simple example is [`fuzz-addr`](tests/fuzz/fuzz-addr.c). It setups the chainparams and
|
|
context (wally, tmpctx, ..) in `init()` then bruteforces the bech32 encoder in `run()`.
|