iproute: Add support for extended ack to rtnl_talk

Add support for extended ack error reporting via libmnl.
Add a new function rtnl_talk_extack that takes a callback as an input
arg. If a netlink response contains extack attributes, the callback is
is invoked with the the err string, offset in the message and a pointer
to the message returned by the kernel.

If iproute2 is built without libmnl, it will still work but
extended error reports from kernel will not be available.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/libnetlink.h b/include/libnetlink.h
index 643c3bc5..69257f0e 100644
--- a/include/libnetlink.h
+++ b/include/libnetlink.h
@@ -76,6 +76,9 @@ typedef int (*rtnl_listen_filter_t)(const struct sockaddr_nl *,
 				    struct rtnl_ctrl_data *,
 				    struct nlmsghdr *n, void *);
 
+typedef int (*nl_ext_ack_fn_t)(const char *errmsg, uint32_t off,
+			       const struct nlmsghdr *inner_nlh);
+
 struct rtnl_dump_filter_arg {
 	rtnl_filter_t filter;
 	void *arg1;
@@ -92,6 +95,9 @@ int rtnl_dump_filter_nc(struct rtnl_handle *rth,
 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
 	      struct nlmsghdr *answer, size_t len)
 	__attribute__((warn_unused_result));
+int rtnl_talk_extack(struct rtnl_handle *rtnl, struct nlmsghdr *n,
+	      struct nlmsghdr *answer, size_t len, nl_ext_ack_fn_t errfn)
+	__attribute__((warn_unused_result));
 int rtnl_talk_suppress_rtnl_errmsg(struct rtnl_handle *rtnl, struct nlmsghdr *n,
 				   struct nlmsghdr *answer, size_t len)
 	__attribute__((warn_unused_result));