fuzz: add P2P message parser harness (#142)

* fuzz: add P2P message parser harness

* fuzz: avoid duplicate legacy header includes

* fuzz: seed the corpus with our network magic, not Bitcoin's

The two seed inputs began f5 be b6 d9, which is Bitcoin's message
start. Ours is bf 20 5c fd. CMessageHeader::IsValid rejects on that
field first, so both seeds died at the first check and the smoke run
exercised the reject path and nothing else.

libFuzzer would have to mutate its way onto four exact bytes before
reaching any parser, which does not happen in 128 runs. The job would
have gone green while covering none of what it was added to cover.

---------

Co-authored-by: Gilcimar Duarte <ti@gpm.infra>
Co-authored-by: Bitflash-sh <btf01@proton.me>

1 files changed, 5 insertions, 2 deletions

diff --git a/Makefile b/Makefile
index 0788b61..736f5d8 100644
--- a/Makefile
+++ b/Makefile
@@ -42,7 +42,7 @@ deps-apt:
         @if command -v apt-get >/dev/null 2>&1; then \
           $(SUDO) apt-get install -y build-essential cmake git pkg-config autoconf \
             libtool libssl-dev libdb5.3++-dev libsodium-dev nlohmann-json3-dev \
-            libboost-system-dev libglfw3-dev libgl-dev python3-pil; \
+            libboost-system-dev libglfw3-dev libgl-dev python3-pil clang; \
         else \
           echo "Not an apt system — install: g++ cmake git autoconf libtool"; \
           echo "  libssl libdb++ libsodium nlohmann-json boost glfw3 opengl python3-pil"; \
@@ -191,6 +191,9 @@ clean:
 tests:
         $(MAKE) -C src -f Makefile tests
 
+fuzz-net-message-smoke: deps-linux
+        $(MAKE) -C src -f Makefile fuzz-net-message-smoke
+
 checksums:
         ./scripts/make-release-checksums.sh
 
@@ -201,5 +204,5 @@ verify-release:
         ./scripts/verify-release.sh $(if $(TAG),$(TAG),latest)
 
 .PHONY: linux windows clean appimage \
-        tests checksums sign-checksums verify-release \
+        tests fuzz-net-message-smoke checksums sign-checksums verify-release \
         deps-linux deps-windows deps-apt deps-secp256k1 deps-randomx