examples: add ct expectation examples

Add examples for ct expectations.

Add, list and delete ct expectation objects from specified table.
Add expectation object to rule.

Signed-off-by: Stéphane Veyret <sveyret@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 163 insertions, 0 deletions

diff --git a/examples/nft-rule-ct-expectation-add.c b/examples/nft-rule-ct-expectation-add.c
new file mode 100644
index 0000000..238e224
--- /dev/null
+++ b/examples/nft-rule-ct-expectation-add.c
@@ -0,0 +1,163 @@
+/*
+ * (C) 2019 by Stéphane Veyret <sveyret@gmail.com>
+ *
+ * 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.
+ */
+
+#include <stdlib.h>
+#include <time.h>
+#include <string.h>
+#include <stddef.h>	/* for offsetof */
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/tcp.h>
+#include <arpa/inet.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <errno.h>
+
+#include <linux/netfilter.h>
+#include <linux/netfilter/nfnetlink.h>
+#include <linux/netfilter/nf_tables.h>
+
+#include <libmnl/libmnl.h>
+#include <libnftnl/rule.h>
+#include <libnftnl/expr.h>
+
+static uint16_t parse_family(char *str, const char *option)
+{
+	if (strcmp(str, "ip") == 0)
+		return NFPROTO_IPV4;
+	else if (strcmp(str, "ip6") == 0)
+		return NFPROTO_IPV6;
+	else if (strcmp(str, "inet") == 0)
+		return NFPROTO_INET;
+	else if (strcmp(str, "arp") == 0)
+		return NFPROTO_INET;
+	fprintf(stderr, "Unknown %s: ip, ip6, inet, arp\n", option);
+	exit(EXIT_FAILURE);
+}
+
+static void add_ct_expect(struct nftnl_rule *r, const char *obj_name)
+{
+	struct nftnl_expr *e;
+
+	e = nftnl_expr_alloc("objref");
+	if (e == NULL) {
+		perror("expr objref oom");
+		exit(EXIT_FAILURE);
+	}
+	nftnl_expr_set_str(e, NFTNL_EXPR_OBJREF_IMM_NAME, obj_name);
+	nftnl_expr_set_u32(e, NFTNL_EXPR_OBJREF_IMM_TYPE, NFT_OBJECT_CT_EXPECT);
+
+	nftnl_rule_add_expr(r, e);
+}
+
+static struct nftnl_rule *setup_rule(uint8_t family, const char *table,
+				     const char *chain, const char *handle,
+				     const char *obj_name)
+{
+	struct nftnl_rule *r = NULL;
+	uint64_t handle_num;
+
+	r = nftnl_rule_alloc();
+	if (r == NULL) {
+		perror("OOM");
+		exit(EXIT_FAILURE);
+	}
+
+	nftnl_rule_set(r, NFTNL_RULE_TABLE, table);
+	nftnl_rule_set(r, NFTNL_RULE_CHAIN, chain);
+	nftnl_rule_set_u32(r, NFTNL_RULE_FAMILY, family);
+
+	if (handle != NULL) {
+		handle_num = atoll(handle);
+		nftnl_rule_set_u64(r, NFTNL_RULE_POSITION, handle_num);
+	}
+
+	add_ct_expect(r, obj_name);
+
+	return r;
+}
+
+int main(int argc, char *argv[])
+{
+	char buf[MNL_SOCKET_BUFFER_SIZE];
+	struct mnl_nlmsg_batch *batch;
+	uint32_t seq = time(NULL);
+	struct mnl_socket *nl;
+	struct nftnl_rule *r;
+	struct nlmsghdr *nlh;
+	uint8_t family;
+	int ret;
+
+	if (argc < 5 || argc > 6) {
+		fprintf(stderr,
+			"Usage: %s <family> <table> <chain> [<handle>] <name>\n",
+			argv[0]);
+		exit(EXIT_FAILURE);
+	}
+	family = parse_family(argv[1], "family");
+
+	if (argc < 6)
+		r = setup_rule(family, argv[2], argv[3], NULL, argv[4]);
+	else
+		r = setup_rule(family, argv[2], argv[3], argv[4], argv[5]);
+
+	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);
+	}
+
+	batch = mnl_nlmsg_batch_start(buf, sizeof(buf));
+
+	nftnl_batch_begin(mnl_nlmsg_batch_current(batch), seq++);
+	mnl_nlmsg_batch_next(batch);
+
+	nlh = nftnl_rule_nlmsg_build_hdr(mnl_nlmsg_batch_current(batch),
+					 NFT_MSG_NEWRULE,
+					 nftnl_rule_get_u32(r, NFTNL_RULE_FAMILY),
+					 NLM_F_APPEND|NLM_F_CREATE|NLM_F_ACK,
+					 seq++);
+
+	nftnl_rule_nlmsg_build_payload(nlh, r);
+	nftnl_rule_free(r);
+	mnl_nlmsg_batch_next(batch);
+
+	nftnl_batch_end(mnl_nlmsg_batch_current(batch), seq++);
+	mnl_nlmsg_batch_next(batch);
+
+	ret = mnl_socket_sendto(nl, mnl_nlmsg_batch_head(batch),
+				mnl_nlmsg_batch_size(batch));
+	if (ret == -1) {
+		perror("mnl_socket_sendto");
+		exit(EXIT_FAILURE);
+	}
+
+	mnl_nlmsg_batch_stop(batch);
+
+	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	if (ret == -1) {
+		perror("mnl_socket_recvfrom");
+		exit(EXIT_FAILURE);
+	}
+
+	ret = mnl_cb_run(buf, ret, 0, mnl_socket_get_portid(nl), NULL, NULL);
+	if (ret < 0) {
+		perror("mnl_cb_run");
+		exit(EXIT_FAILURE);
+	}
+
+	mnl_socket_close(nl);
+
+	return EXIT_SUCCESS;
+}