bpfjit

Just-In-Time compiler for Berkeley Packet Filter extracted from NetBSD.

Manpage: https://man.netbsd.org/bpfjit.4

bpfjit depends on sljit: https://github.com/zherczeg/sljit/

This repo contains the bpfjit files and their history extracted from the NetBSD repo at https://github.com/NetBSD/src. The files are patched to be able to build using the latest version of sljit. There are also some changes to be able to use this library together with libpcap.

See the script update.sh for details about how the file history is extracted, and the patch files in patches/ for reason of each change.

Build configurations

Bpfjit can be configured at build time using following defines:

• SLJIT_VERBOSE - Enabled by default in sljit

  Unless disabled bpfjit will print generated machine code to stderr. Recommended to be disabled in production and requires disabling in both bpfjit and sljit.

• BPFJIT_USE_UDIV - Disabled by default in bpfjit

  Generate udiv instructions instead of function calls for divide or modulus handling.

Build using Make

Building bpfjit requires a static library sljit and its header files to be installed on the system. The Makefile provides build targets to build and install sljit for testing.

# Optional:
# Download, build and install dependency sljit
sudo make EXTRA_CPPFLAGS="-DSLJIT_VERBOSE=0" install-sljit

# Build and install bpfjit
sudo make CPPFLAGS="-DSLJIT_VERBOSE=0" install

The libraries can also be built and installed to a local directory, this avoids the need of sudo:

# Prepare a local installation
mkdir /tmp/stage

# Download, build and install dependency sljit
PREFIX=/tmp/stage make install-sljit

# Build and install bpfjit
PREFIX=/tmp/stage make install

# Optional: Build and run tests
PREFIX=/tmp/stage make test

# Optional: Build and run tests that requires package `libpcap-dev`
PREFIX=/tmp/stage make test-with-pcap

Build using CMake

The library can also be built using CMake and the configs provides build and install targets. During the build generation step the dependency sljit with be searched for and needs to be installed on the system as a prerequisite.

# Optional:
# Download, build and install dependency sljit
sudo make EXTRA_CPPFLAGS="-DSLJIT_VERBOSE=0" install-sljit

# Build bpjfit
mkdir -p build && cd build
cmake -D CMAKE_C_FLAGS="-DSLJIT_VERBOSE=0" ..
make

# Install bpfjit
sudo make install

The library can also be installed to a local directory, this avoids the need of sudo and both DESTDIR and prefix are handled.

# Prepare a local installation
mkdir /tmp/stage

# Download, build and install dependency sljit
PREFIX=/tmp/stage make install-sljit

# Build bpfjit
mkdir -p build && cd build
cmake -DCMAKE_PREFIX_PATH=/tmp/stage ..
make

# Install bpfjit using prefix
# This avoids usage of paths containing `/usr/local/`
cmake --install . --prefix /tmp/stage

# Optional: Build and run tests
make bpfjit-test
./bpfjit-test

# Optional: Build and run tests that requires package `libpcap-dev`
make bpfjit-test-with-pcap
./bpfjit-test-with-pcap