src: consolidate netlink build header function

Add new function nft_nlmsg_build_hdr which consolidates all existing
functions to build headers per object. They basically look the same.
This patch still provides aliases for consistency in the naming
approach.

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

1 files changed, 36 insertions, 0 deletions

diff --git a/src/common.c b/src/common.c
new file mode 100644
index 0000000..f03e730
--- /dev/null
+++ b/src/common.c
@@ -0,0 +1,36 @@
+/*
+ * (C) 2012-2013 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.
+ */
+
+#include <linux/netlink.h>
+#include <linux/netfilter/nfnetlink.h>
+
+#include <libmnl/libmnl.h>
+#include <libnftables/common.h>
+
+#include "internal.h"
+
+struct nlmsghdr *nft_nlmsg_build_hdr(char *buf, uint16_t cmd, uint16_t family,
+				     uint16_t type, uint32_t seq)
+{
+	struct nlmsghdr *nlh;
+	struct nfgenmsg *nfh;
+
+	nlh = mnl_nlmsg_put_header(buf);
+	nlh->nlmsg_type = (NFNL_SUBSYS_NFTABLES << 8) | cmd;
+	nlh->nlmsg_flags = NLM_F_REQUEST | type;
+	nlh->nlmsg_seq = seq;
+
+	nfh = mnl_nlmsg_put_extra_header(nlh, sizeof(struct nfgenmsg));
+	nfh->nfgen_family = family;
+	nfh->version = NFNETLINK_V0;
+	nfh->res_id = 0;
+
+	return nlh;
+}
+EXPORT_SYMBOL(nft_nlmsg_build_hdr);