examples: add nft-compat-get

This utility allows to consult x_tables match/target revisions supported
via the nft_compat layer.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

4 files changed, 166 insertions, 2 deletions

diff --git a/examples/Makefile.am b/examples/Makefile.am
index 1c72ab4..31e53bf 100644
--- a/examples/Makefile.am
+++ b/examples/Makefile.am
@@ -8,7 +8,8 @@ check_PROGRAMS = nft-table-add		\
 		 nft-chain-get		\
 		 nft-rule-add		\
 		 nft-rule-del		\
-		 nft-rule-get
+		 nft-rule-get		\
+		 nft-compat-get
 
 nft_table_add_SOURCES = nft-table-add.c
 nft_table_add_LDADD = ../src/libnftables.la ${LIBMNL_LIBS}
@@ -36,3 +37,6 @@ nft_rule_del_LDADD = ../src/libnftables.la ${LIBMNL_LIBS}
 
 nft_rule_get_SOURCES = nft-rule-get.c
 nft_rule_get_LDADD = ../src/libnftables.la ${LIBMNL_LIBS}
+
+nft_compat_get_SOURCES = nft-compat-get.c
+nft_compat_get_LDADD = ../src/libnftables.la ${LIBMNL_LIBS}
diff --git a/examples/nft-compat-get.c b/examples/nft-compat-get.c
new file mode 100644
index 0000000..3294028
--- /dev/null
+++ b/examples/nft-compat-get.c
@@ -0,0 +1,139 @@
+/*
+ * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * 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 software has been sponsored by Sophos Astaro <http://www.sophos.com>
+ */
+
+#include <stdlib.h>
+#include <time.h>
+#include <string.h>
+#include <netinet/in.h>
+
+#include <linux/netfilter/nfnetlink.h>
+#include <linux/netfilter/nf_tables_compat.h>
+
+#include <libmnl/libmnl.h>
+
+static int data_attr_cb(const struct nlattr *attr, void *data)
+{
+	const struct nlattr **tb = data;
+	int type = mnl_attr_get_type(attr);
+
+	if (mnl_attr_type_valid(attr, NFTA_COMPAT_MAX) < 0)
+		return MNL_CB_OK;
+
+	switch(type) {
+	case NFTA_COMPAT_NAME:
+		if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0) {
+			perror("mnl_attr_validate");
+			return MNL_CB_ERROR;
+		}
+		break;
+	case NFTA_COMPAT_REV:
+	case NFTA_COMPAT_TYPE:
+		if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0) {
+			perror("mnl_attr_validate");
+			return MNL_CB_ERROR;
+		}
+		break;
+	}
+	tb[type] = attr;
+	return MNL_CB_OK;
+}
+
+static int cb(const struct nlmsghdr *nlh, void *data)
+{
+	struct nlattr *tb[NFTA_COMPAT_MAX+1] = {};
+	struct nfgenmsg *nfg = mnl_nlmsg_get_payload(nlh);
+
+	mnl_attr_parse(nlh, sizeof(*nfg), data_attr_cb, tb);
+
+	if (tb[NFTA_COMPAT_NAME])
+		printf("name=%s ", mnl_attr_get_str(tb[NFTA_COMPAT_NAME]));
+	if (tb[NFTA_COMPAT_REV])
+		printf("rev=%d ", ntohl(mnl_attr_get_u32(tb[NFTA_COMPAT_REV])));
+	if (tb[NFTA_COMPAT_TYPE])
+		printf("type=%d ", ntohl(mnl_attr_get_u32(tb[NFTA_COMPAT_REV])));
+
+	printf("\n");
+
+	return MNL_CB_OK;
+}
+
+int main(int argc, char *argv[])
+{
+	struct mnl_socket *nl;
+	char buf[MNL_SOCKET_BUFFER_SIZE];
+	struct nlmsghdr *nlh;
+	uint32_t portid, seq, rev, type;
+	int ret;
+
+	if (argc != 4) {
+		fprintf(stderr, "Usage: %s <extension_name> <type> <rev>\n",
+			argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	if (strcmp(argv[2], "target") == 0)
+		type = 1;
+	else if (strcmp(argv[2], "match") == 0)
+		type = 0;
+	else {
+		fprintf(stderr, "type should be `target' or `match'\n");
+		return EXIT_FAILURE;
+	}
+	rev = atoi(argv[3]);
+
+	nlh = mnl_nlmsg_put_header(buf);
+	nlh->nlmsg_type = (NFNL_SUBSYS_NFT_COMPAT << 8) | NFNL_MSG_COMPAT_GET;
+	nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
+	nlh->nlmsg_seq = seq = time(NULL);
+
+	struct nfgenmsg *nfg = mnl_nlmsg_put_extra_header(nlh, sizeof(*nfg));
+	nfg->nfgen_family = AF_INET;
+	nfg->version = NFNETLINK_V0;
+	nfg->res_id = 0;
+
+	mnl_attr_put_strz(nlh, NFTA_COMPAT_NAME, argv[1]);
+	mnl_attr_put_u32(nlh, NFTA_COMPAT_REV, htonl(rev));
+	mnl_attr_put_u32(nlh, NFTA_COMPAT_TYPE, htonl(type));
+
+	printf("requesting `%s' rev=%d type=%d\n", argv[1], rev, type);
+
+	nl = mnl_socket_open(NETLINK_NETFILTER);
+	if (nl == NULL) {
+		perror("mnl_socket_open");
+		exit(EXIT_FAILURE);
+	}
+
+	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
+		perror("mnl_socket_bind");
+		exit(EXIT_FAILURE);
+	}
+	portid = mnl_socket_get_portid(nl);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		perror("mnl_socket_send");
+		exit(EXIT_FAILURE);
+	}
+
+	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	while (ret > 0) {
+		ret = mnl_cb_run(buf, ret, seq, portid, cb, NULL);
+		if (ret <= 0)
+			break;
+		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	}
+	if (ret == -1) {
+		perror("error");
+		exit(EXIT_FAILURE);
+	}
+	mnl_socket_close(nl);
+
+	return EXIT_SUCCESS;
+}
diff --git a/include/linux/netfilter/nf_tables_compat.h b/include/linux/netfilter/nf_tables_compat.h
new file mode 100644
index 0000000..36fb81d
--- /dev/null
+++ b/include/linux/netfilter/nf_tables_compat.h
@@ -0,0 +1,20 @@
+#ifndef _NFT_COMPAT_NFNETLINK_H_
+#define _NFT_COMPAT_NFNETLINK_H_
+
+#define NFT_COMPAT_NAME_MAX	32
+
+enum {
+	NFNL_MSG_COMPAT_GET,
+	NFNL_MSG_COMPAT_MAX
+};
+
+enum {
+	NFTA_COMPAT_UNSPEC = 0,
+	NFTA_COMPAT_NAME,
+	NFTA_COMPAT_REV,
+	NFTA_COMPAT_TYPE,
+	__NFTA_COMPAT_MAX,
+};
+#define NFTA_COMPAT_MAX (__NFTA_COMPAT_MAX - 1)
+
+#endif
diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h
index 0d2e4fb..91eebab 100644
--- a/include/linux/netfilter/nfnetlink.h
+++ b/include/linux/netfilter/nfnetlink.h
@@ -54,7 +54,8 @@ struct nfgenmsg {
 #define NFNL_SUBSYS_CTNETLINK_TIMEOUT	8
 #define NFNL_SUBSYS_CTHELPER		9
 #define NFNL_SUBSYS_NFTABLES		10
-#define NFNL_SUBSYS_COUNT		11
+#define NFNL_SUBSYS_NFT_COMPAT		11
+#define NFNL_SUBSYS_COUNT		12
 
 #ifdef __KERNEL__