examples: add nfct-counter

Provide replacement for:

/proc/sys/net/netfilter/nf_conntrack_count

Requires Linux >= 3.6.x

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

2 files changed, 98 insertions, 0 deletions

diff --git a/examples/netfilter/Makefile.am b/examples/netfilter/Makefile.am
index 644f5cd..1671d1f 100644
--- a/examples/netfilter/Makefile.am
+++ b/examples/netfilter/Makefile.am
@@ -4,6 +4,7 @@ check_PROGRAMS = nf-queue \
 		 nf-log \
 		 nfct-event \
 		 nfct-dump-stats-cpu \
+		 nfct-counter \
 		 nfct-create-batch
 
 nf_queue_SOURCES = nf-queue.c
@@ -18,5 +19,8 @@ nfct_event_LDADD = ../../src/libmnl.la
 nfct_dump_stats_cpu_SOURCES = nfct-dump-stats-cpu.c
 nfct_dump_stats_cpu_LDADD = ../../src/libmnl.la
 
+nfct_counter_SOURCES = nfct-counter.c
+nfct_counter_LDADD = ../../src/libmnl.la
+
 nfct_create_batch_SOURCES = nfct-create-batch.c
 nfct_create_batch_LDADD = ../../src/libmnl.la
diff --git a/examples/netfilter/nfct-counter.c b/examples/netfilter/nfct-counter.c
new file mode 100644
index 0000000..29bb36a
--- /dev/null
+++ b/examples/netfilter/nfct-counter.c
@@ -0,0 +1,94 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+#include <arpa/inet.h>
+
+#include <linux/netfilter/nfnetlink_conntrack.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, CTA_STATS_GLOBAL_MAX) < 0)
+		return MNL_CB_OK;
+
+	if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0) {
+		perror("mnl_attr_validate");
+		return MNL_CB_ERROR;
+	}
+
+	tb[type] = attr;
+	return MNL_CB_OK;
+}
+
+static int data_cb(const struct nlmsghdr *nlh, void *data)
+{
+	struct nlattr *tb[CTA_STATS_GLOBAL_MAX+1] = {};
+	struct nfgenmsg *nfg = mnl_nlmsg_get_payload(nlh);
+
+	mnl_attr_parse(nlh, sizeof(*nfg), data_attr_cb, tb);
+
+	if (tb[CTA_STATS_GLOBAL_ENTRIES]) {
+		int ctr = ntohl(mnl_attr_get_u32(tb[CTA_STATS_GLOBAL_ENTRIES]));
+		printf("%d\n", ctr);
+	}
+	return MNL_CB_OK;
+}
+
+int main(void)
+{
+	struct mnl_socket *nl;
+	struct nlmsghdr *nlh;
+	struct nfgenmsg *nfh;
+	char buf[MNL_SOCKET_BUFFER_SIZE];
+	unsigned int seq, portid;
+	int ret;
+
+	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);
+
+	nlh = mnl_nlmsg_put_header(buf);
+	nlh->nlmsg_type = (NFNL_SUBSYS_CTNETLINK << 8) |
+			  IPCTNL_MSG_CT_GET_STATS;
+	nlh->nlmsg_flags = NLM_F_REQUEST;
+	nlh->nlmsg_seq = seq = time(NULL);
+
+	nfh = mnl_nlmsg_put_extra_header(nlh, sizeof(struct nfgenmsg));
+	nfh->nfgen_family = AF_INET;
+	nfh->version = NFNETLINK_V0;
+	nfh->res_id = 0;
+
+	ret = mnl_socket_sendto(nl, nlh, nlh->nlmsg_len);
+	if (ret == -1) {
+		perror("mnl_socket_recvfrom");
+		exit(EXIT_FAILURE);
+	}
+
+	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	if (ret == -1) {
+		perror("mnl_socket_recvfrom");
+		exit(EXIT_FAILURE);
+	}
+
+	ret = mnl_cb_run(buf, ret, seq, portid, data_cb, NULL);
+	if (ret == -1) {
+		perror("mnl_cb_run");
+		exit(EXIT_FAILURE);
+	}
+
+	mnl_socket_close(nl);
+
+	return 0;
+}