1 files changed, 37 insertions, 0 deletions
diff --git a/fuzz/FUZZING.md b/fuzz/FUZZING.md
new file mode 100644
index 0000000..65363e1
--- /dev/null
+++ b/fuzz/FUZZING.md
@@ -0,0 +1,37 @@
+<!--
+Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+
+SPDX-License-Identifier: MPL-2.0
+
+This Source Code Form is subject to the terms of the Mozilla Public
+License, v. 2.0.  If a copy of the MPL was not distributed with this
+file, you can obtain one at https://mozilla.org/MPL/2.0/.
+
+See the COPYRIGHT file distributed with this work for additional
+information regarding copyright ownership.
+-->
+
+= Fuzzing
+
+The tests in this directory can be operated in three modes:
+
+* non-fuzzing - the test just runs over all input located in `<test_name>.in/`
+  directory by compiling with mock main.c that walks through the directory and
+  runs `LLVMFuzzerTestOneInput()` over the input files
+* AFL - `./configure --with-fuzzing=afl` will either feed the stdin to
+  `LLVMFuzzerTestOneInput()` or run the `__AFL_LOOP(10000)` if compiled with
+  `afl-clang-fast`
+* LibFuzzer - `./configure --with-fuzzing=libfuzzer` will disable `main.c`
+  completely and it uses the standard LibFuzzer mechanims to feed
+  `LLVMFuzzerTestOneInput` with the fuzzer
+
+== Test Cases
+
+Each test case should be called descriptively and the executable target must
+link `testcase.o` and `main.o` and the `test_case.c` must have a function
+`LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)`.
+
+== Adding more fuzzers
+
+To add a different fuzzer, `main.c` must be modified to include `main()` function
+for a specific fuzzer (or no function as is case with LibFuzzer).