utils: nfbpf_compile

A BPF compiler to convert tcpdump expressions to the decimal format
accepted by the libxt_bpf.

Generate a file and pass that to iptables:

  nfbpf_compile RAW 'udp dst port 9000' > test.bpf
  iptables -A OUTPUT -m bpf --bytecode-file test.bpf -j LOG

Or pass the output directly to iptables using backticks:

  iptables -A INPUT -m bpf --bytecode \
      "`./nfbpf_compile RAW 'udp dst port 9000'" -j LOG

This utility depends on libpcap. The library is only compiled if the option
--enable-bpf-compiler is explicitly passed to ./configure and libpcap is
found.

Pablo has mangled the original patch to rename the utility to
nfbpf_compile. Also modified the output to match exactly what
-m bpf --bytecode needs.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 2ba5cecb..06204665 100644
--- a/configure.ac
+++ b/configure.ac
@@ -50,6 +50,9 @@ AC_ARG_ENABLE([devel],
 	[enable_devel="$enableval"], [enable_devel="yes"])
 AC_ARG_ENABLE([libipq],
 	AS_HELP_STRING([--enable-libipq], [Build and install libipq]))
+AC_ARG_ENABLE([bpf-compiler],
+	AS_HELP_STRING([--enable-bpf-compiler], [Build bpf compiler]),
+	[enable_bpfc="yes"])
 AC_ARG_WITH([pkgconfigdir], AS_HELP_STRING([--with-pkgconfigdir=PATH],
 	[Path to the pkgconfig directory [[LIBDIR/pkgconfig]]]),
 	[pkgconfigdir="$withval"], [pkgconfigdir='${libdir}/pkgconfig'])
@@ -88,6 +91,7 @@ AM_CONDITIONAL([ENABLE_IPV6], [test "$enable_ipv6" = "yes"])
 AM_CONDITIONAL([ENABLE_LARGEFILE], [test "$enable_largefile" = "yes"])
 AM_CONDITIONAL([ENABLE_DEVEL], [test "$enable_devel" = "yes"])
 AM_CONDITIONAL([ENABLE_LIBIPQ], [test "$enable_libipq" = "yes"])
+AM_CONDITIONAL([ENABLE_BPFC], [test "$enable_bpfc" = "yes"])
 
 PKG_CHECK_MODULES([libnfnetlink], [libnfnetlink >= 1.0],
 	[nfnetlink=1], [nfnetlink=0])