xtables: bootstrap ARP compatibility layer for nftables

This patch bootstraps ARP support for the compatibility layer:

1) copy original arptables code into xtables-arp.c
2) adapt it to fit into the existing nft infrastructure.
3) add the builtin table/chains for ARP.
4) add necessary parts so xtables-multi can provide xtables-arp.
5) add basic support for rule addition (-A), insertion (-I) and
   listing (-L).

[ This was originally posted in a series of patches with interdependencies
  that I have collapsed to leave the repository in consistent state. This
  patch includes the following changes I made:

* Rename from xtables-arptables to xtables-arp, previous name too long.
* Remove nft-arptables.c, now we have one single nft-arp.c file. Moved
  specific ARP functions to nft.c. Those should go away at some point as
  some refactorization should allow to accomodate those functions to the
  existing infrastructure.
* Fix --opcode Request/Reply, so we can do something useful with this
  like dropping ARP request/replies.

--pablo ]

Signed-off-by: Giuseppe Longo <giuseppelng@gmail.com>
Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 86 insertions, 0 deletions

diff --git a/iptables/xtables-arp-standalone.c b/iptables/xtables-arp-standalone.c
new file mode 100644
index 00000000..186c9a1e
--- /dev/null
+++ b/iptables/xtables-arp-standalone.c
@@ -0,0 +1,86 @@
+/*
+ * Author: Paul.Russell@rustcorp.com.au and mneuling@radlogic.com.au
+ *
+ * Based on the ipchains code by Paul Russell and Michael Neuling
+ *
+ * (C) 2000-2002 by the netfilter coreteam <coreteam@netfilter.org>:
+ * 		    Paul 'Rusty' Russell <rusty@rustcorp.com.au>
+ * 		    Marc Boucher <marc+nf@mbsi.ca>
+ * 		    James Morris <jmorris@intercode.com.au>
+ * 		    Harald Welte <laforge@gnumonks.org>
+ * 		    Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
+ *
+ *	arptables -- IP firewall administration for kernels with
+ *	firewall table (aimed for the 2.3 kernels)
+ *
+ *	See the accompanying manual page arptables(8) for information
+ *	about proper usage of this program.
+ *
+ *	This program is free software; you can redistribute it and/or modify
+ *	it under the terms of the GNU General Public License as published by
+ *	the Free Software Foundation; either version 2 of the License, or
+ *	(at your option) any later version.
+ *
+ *	This program is distributed in the hope that it will be useful,
+ *	but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *	GNU General Public License for more details.
+ *
+ *	You should have received a copy of the GNU General Public License
+ *	along with this program; if not, write to the Free Software
+ *	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <xtables.h>
+#include "nft.h"
+#include <linux/netfilter_arp/arp_tables.h>
+
+#include "xtables-multi.h"
+
+extern struct xtables_globals xtables_globals;
+extern const char *program_version, *program_name;
+
+static const struct xtables_afinfo afinfo_arp = {
+        .kmod          = "arp_tables",
+        .proc_exists   = "/proc/net/arp_tables_names",
+        .libprefix     = "libarp_",
+        .family        = NFPROTO_ARP,
+        .ipproto       = IPPROTO_IP,
+        .so_rev_match  = -1,
+        .so_rev_target = -1,
+};
+
+int xtables_arp_main(int argc, char *argv[])
+{
+	int ret;
+	char *table = "filter";
+	struct nft_handle h = {
+		.family = NFPROTO_ARP,
+	};
+
+	xtables_globals.program_name = "xtables-arp";
+	/* This code below could be replaced by xtables_init_all, which
+	 * doesn't support NFPROTO_ARP yet.
+	 */
+	xtables_init();
+	afinfo = &afinfo_arp;
+	ret = xtables_set_params(&xtables_globals);
+	if (ret < 0) {
+		fprintf(stderr, "%s/%s Failed to initialize xtables\n",
+				xtables_globals.program_name,
+				xtables_globals.program_version);
+		exit(1);
+	}
+
+#if defined(ALL_INCLUSIVE) || defined(NO_SHARED_LIBS)
+	init_extensions();
+#endif
+
+	ret = do_commandarp(&h, argc, argv, &table);
+
+	exit(!ret);
+}