Fuzz testing

go-guerrilla fuzz testing

For further improving the stability of the software, some simple fuzz testing was implemented. This is making usage of the go-fuzz package and can easily be performed. The tests itself are all in the fuzz.go file.

Preperations

Branches

We do have an extra branch for this, as not everyone needs the extended code for just running the software. Please checkout the branch tests for this:

$ git checkout tests $ git pull

We try to keep the branch up to date with the master branch.

go-fuzz

If you don’t have go-fuzz already installed, do that now.

$ go get github.com/dvyukov/go-fuzz/go-fuzz $ go get github.com/dvyukov/go-fuzz/go-fuzz-build

Build the packages and you should get the go-fuzz as well as the go-fuzz-build tools.

Corpus files

If you have pulled the recent tests branch you should now also have the workdir and within that the corpus folder. This contains some files that are used to initate the fuzzing. You are very welcome to create further corpus files, the ones we use are the example smtp files of the go-fuzz package.

Putting it together

After everything is prepared you can start. Build the package with go-fuzz:

$ go-fuzz-build github.com/flashmob/go-guerrilla

This will take a while and create a file named guerrilla-fuzz.zip Now the fuzzing process itself can be started:

$ go-fuzz -bin=guerrilla-fuzz.zip -workdir=workdir

This will run for quite a while. Eventually you will get an output that contains crashers.

You can investigate on those crashes looking at the .output files in the workdir/crashers folder.

Further improvements

Currently we just do fuzz testing on a very high level: We spin up the server, wait for the greeting and issue the command created by go-fuzz. For future improvements, this fuzzing should be made against more atomic functions, e.g. the handling of commands. This would need some changes on the server code itself and is due to upcoming refactoring.