libnetlink: Add rta_getattr_uint()

NLA_UINT attributes have a 4-byte payload if possible, and an 8-byte one if
necessary. Add a function to extract these. Since we need to dispatch on
length anyway, make the getter truly universal by supporting also u8 and
u16.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David Ahern <dsahern@kernel.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/libnetlink.h b/include/libnetlink.h
index ad7e71272..35a9bb57d 100644
--- a/include/libnetlink.h
+++ b/include/libnetlink.h
@@ -260,6 +260,20 @@ static inline __u64 rta_getattr_u64(const struct rtattr *rta)
 	memcpy(&tmp, RTA_DATA(rta), sizeof(__u64));
 	return tmp;
 }
+static inline __u64 rta_getattr_uint(const struct rtattr *rta)
+{
+	switch (RTA_PAYLOAD(rta)) {
+	case sizeof(__u8):
+		return rta_getattr_u8(rta);
+	case sizeof(__u16):
+		return rta_getattr_u16(rta);
+	case sizeof(__u32):
+		return rta_getattr_u32(rta);
+	case sizeof(__u64):
+		return rta_getattr_u64(rta);
+	}
+	return -1ULL;
+}
 static inline __s32 rta_getattr_s32(const struct rtattr *rta)
 {
 	return *(__s32 *)RTA_DATA(rta);