[libnftnl PATCH 4/4] examples: fix nft-set-elem-del.c by adding batching support

[Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>]

Let's add batching support to this code example. The kernel API only
understand messages in batch format.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
---
 examples/nft-set-elem-del.c |  107 ++++++++++++++++++++++++++++++-------------
 1 file changed, 74 insertions(+), 33 deletions(-)

diff --git a/examples/nft-set-elem-del.c b/examples/nft-set-elem-del.c
index af70cde..9da6f08 100644
--- a/examples/nft-set-elem-del.c
+++ b/examples/nft-set-elem-del.c
@@ -16,18 +16,64 @@
 
 #include <linux/netfilter.h>
 #include <linux/netfilter/nf_tables.h>
+#include <linux/netfilter/nfnetlink.h>
 
 #include <libmnl/libmnl.h>
 #include <libnftnl/set.h>
 
+static void setup_set(struct nft_set *s, const char *table, const char *name)
+{
+	uint32_t data;
+	struct nft_set_elem *e;
+
+	nft_set_attr_set(s, NFT_SET_ATTR_TABLE, table);
+	nft_set_attr_set(s, NFT_SET_ATTR_NAME, name);
+
+	/* Add to dummy elements to set */
+	e = nft_set_elem_alloc();
+	if (e == NULL) {
+		perror("OOM");
+		exit(EXIT_FAILURE);
+	}
+
+	data = 0x1;
+	nft_set_elem_attr_set(e, NFT_SET_ELEM_ATTR_KEY, &data, sizeof(data));
+	nft_set_elem_add(s, e);
+
+	e = nft_set_elem_alloc();
+	if (e == NULL) {
+		perror("OOM");
+		exit(EXIT_FAILURE);
+	}
+	data = 0x2;
+	nft_set_elem_attr_set(e, NFT_SET_ELEM_ATTR_KEY, &data, sizeof(data));
+	nft_set_elem_add(s, e);
+}
+
+static void nft_mnl_batch_put(char *buf, uint16_t type, uint32_t seq)
+{
+	struct nlmsghdr *nlh;
+	struct nfgenmsg *nfg;
+
+	nlh = mnl_nlmsg_put_header(buf);
+	nlh->nlmsg_type = type;
+	nlh->nlmsg_flags = NLM_F_REQUEST;
+	nlh->nlmsg_seq = seq;
+
+	nfg = mnl_nlmsg_put_extra_header(nlh, sizeof(*nfg));
+	nfg->nfgen_family = AF_INET;
+	nfg->version = NFNETLINK_V0;
+	nfg->res_id = NFNL_SUBSYS_NFTABLES;
+}
+
 int main(int argc, char *argv[])
 {
 	struct mnl_socket *nl;
+	struct mnl_nlmsg_batch *batch;
 	char buf[MNL_SOCKET_BUFFER_SIZE];
 	struct nlmsghdr *nlh;
-	uint32_t portid, seq, family, data;
+	uint32_t portid, seq, family;
 	struct nft_set *s;
-	struct nft_set_elem *e;
 	int ret;
 
 	if (argc != 4) {
@@ -55,33 +101,24 @@ int main(int argc, char *argv[])
 		exit(EXIT_FAILURE);
 	}
 
-	nft_set_attr_set(s, NFT_SET_ATTR_TABLE, argv[2]);
-	nft_set_attr_set(s, NFT_SET_ATTR_NAME, argv[3]);
-
-	/* Add to dummy elements to set */
-	e = nft_set_elem_alloc();
-	if (e == NULL) {
-		perror("OOM");
-		exit(EXIT_FAILURE);
-	}
+	setup_set(s, argv[2], argv[3]);
 
-	data = 0x1;
-	nft_set_elem_attr_set(e, NFT_SET_ELEM_ATTR_KEY, &data, sizeof(data));
-	nft_set_elem_add(s, e);
+	batch = mnl_nlmsg_batch_start(buf, sizeof(buf));
 
-	e = nft_set_elem_alloc();
-	if (e == NULL) {
-		perror("OOM");
-		exit(EXIT_FAILURE);
-	}
-	data = 0x2;
-	nft_set_elem_attr_set(e, NFT_SET_ELEM_ATTR_KEY, &data, sizeof(data));
-	nft_set_elem_add(s, e);
+	nft_mnl_batch_put(mnl_nlmsg_batch_current(batch),
+			  NFNL_MSG_BATCH_BEGIN, seq++);
+	mnl_nlmsg_batch_next(batch);
 
-	nlh = nft_set_nlmsg_build_hdr(buf, NFT_MSG_DELSETELEM, family,
-				      NLM_F_ACK, seq);
+	nlh = nft_set_nlmsg_build_hdr(mnl_nlmsg_batch_current(batch),
+				      NFT_MSG_DELSETELEM, family,
+				      NLM_F_ACK, seq++);
 	nft_set_elems_nlmsg_build_payload(nlh, s);
 	nft_set_free(s);
+	mnl_nlmsg_batch_next(batch);
+
+	nft_mnl_batch_put(mnl_nlmsg_batch_current(batch),
+			  NFNL_MSG_BATCH_END, seq++);
+	mnl_nlmsg_batch_next(batch);
 
 	nl = mnl_socket_open(NETLINK_NETFILTER);
 	if (nl == NULL) {
@@ -95,20 +132,24 @@ int main(int argc, char *argv[])
 	}
 	portid = mnl_socket_get_portid(nl);
 
-	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
-		perror("mnl_socket_send");
+	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));
-	while (ret > 0) {
-		ret = mnl_cb_run(buf, ret, seq, portid, NULL, NULL);
-		if (ret <= 0)
-			break;
-		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
-	}
 	if (ret == -1) {
-		perror("error");
+		perror("mnl_socket_recvfrom");
+		exit(EXIT_FAILURE);
+	}
+
+	ret = mnl_cb_run(buf, ret, 0, portid, NULL, NULL);
+	if (ret < 0) {
+		perror("mnl_cb_run");
 		exit(EXIT_FAILURE);
 	}
 	mnl_socket_close(nl);