{ final, prev, sources, ... }:
{
  preserve-dscp = prev.stdenv.mkDerivation rec {
    pname = "preserve-dscp";
    inherit (sources.bpf-examples) version src;

    patches = [ ./kern_env.patch ./kern_sec_classifier.patch ];

    makeFlags = [ "PREFIX=$(out)" ];
    buildFlags = [ "preserve-dscp" ];

    CPATH = prev.lib.makeSearchPathOutput "dev" "include" (buildInputs ++ nativeBuildInputs);
    BPF_CFLAGS = "-Wno-unused-command-line-argument -fno-stack-protector";

    outputs = [ "out" "lib" ];

    buildInputs = with final; [ elfutils libpcap zlib ];
    nativeBuildInputs = with final; [ llvmPackages.clang llvmPackages.llvm pkgconfig bpftool libmnl gnum4 glibc_multi makeWrapper ];

    installPhase = ''
      mkdir -p $lib/lib/bpf
      install -t $lib/lib/bpf \
        preserve-dscp/preserve_dscp_kern.o

      mkdir -p $out/bin
      install -m 555 -t $out/bin \
        preserve-dscp/preserve-dscp
      wrapProgram $out/bin/preserve-dscp \
        --set-default PRESERVE_DSCP_KERN $lib/lib/bpf/preserve_dscp_kern.o
    '';

    dontFixup = true;

    meta.mainProgram = "preserve-dscp";
  };
}