Subject: [PATCH v2 iproute-next 05/10] libnetlink: Add helper to create nexthop dump request

From: David Ahern <[email-masked]>
Date: Fri, 7 Jun 2019 15:38:11 -0700

From: David Ahern <[email-masked]>

Add rtnl_nexthopdump_req to initiate a dump request of nexthop objects.

Signed-off-by: David Ahern <[email-masked]>
---
 include/libnetlink.h |  4 ++++
 lib/libnetlink.c     | 27 +++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/include/libnetlink.h b/include/libnetlink.h
index 599b2c592f68..1ddba8dcd220 100644
--- a/include/libnetlink.h
+++ b/include/libnetlink.h
@@ -93,6 +93,10 @@ int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req,
 int rtnl_dump_request_n(struct rtnl_handle *rth, struct nlmsghdr *n)
 	__attribute__((warn_unused_result));
 
+int rtnl_nexthopdump_req(struct rtnl_handle *rth, int family,
+			 req_filter_fn_t filter_fn)
+	__attribute__((warn_unused_result));
+
 struct rtnl_ctrl_data {
 	int	nsid;
 };
diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index eb85bbdf01ee..af2a3bbfd29b 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -25,6 +25,7 @@
 #include <linux/fib_rules.h>
 #include <linux/if_addrlabel.h>
 #include <linux/if_bridge.h>
+#include <linux/nexthop.h>
 
 #include "libnetlink.h"
 
@@ -252,6 +253,32 @@ int rtnl_open(struct rtnl_handle *rth, unsigned int subscriptions)
 	return rtnl_open_byproto(rth, subscriptions, NETLINK_ROUTE);
 }
 
+int rtnl_nexthopdump_req(struct rtnl_handle *rth, int family,
+			 req_filter_fn_t filter_fn)
+{
+	struct {
+		struct nlmsghdr nlh;
+		struct nhmsg nhm;
+		char buf[128];
+	} req = {
+		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct nhmsg)),
+		.nlh.nlmsg_type = RTM_GETNEXTHOP,
+		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
+		.nlh.nlmsg_seq = rth->dump = ++rth->seq,
+		.nhm.nh_family = family,
+	};
+
+	if (filter_fn) {
+		int err;
+
+		err = filter_fn(&req.nlh, sizeof(req));
+		if (err)
+			return err;
+	}
+
+	return send(rth->fd, &req, sizeof(req), 0);
+}
+
 int rtnl_addrdump_req(struct rtnl_handle *rth, int family,
 		      req_filter_fn_t filter_fn)
 {
-- 
2.11.0