libnetlink: add parse_rtattr_one_nested helper

Sometimes, it is more convenient to get only one specific nested attribute by
type. For example for IFLA_AF_SPEC where type is address family (AF_INET6).
So add this helper for this purpose.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>

diff --git a/include/libnetlink.h b/include/libnetlink.h
index db0496945177206b45f99cf7504814576994ba58..de7c85f3731edee48cde67c879c7ac7a6420123d 100644 (file)
--- a/include/libnetlink.h
+++ b/include/libnetlink.h
@@ -82,11 +82,15 @@ extern int parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta, int le
 extern int parse_rtattr_flags(struct rtattr *tb[], int max, struct rtattr *rta,
                              int len, unsigned short flags);
 extern int parse_rtattr_byindex(struct rtattr *tb[], int max, struct rtattr *rta, int len);
+extern struct rtattr *parse_rtattr_one(int type, struct rtattr *rta, int len);
 extern int __parse_rtattr_nested_compat(struct rtattr *tb[], int max, struct rtattr *rta, int len);
 
 #define parse_rtattr_nested(tb, max, rta) \
        (parse_rtattr((tb), (max), RTA_DATA(rta), RTA_PAYLOAD(rta)))
 
+#define parse_rtattr_one_nested(type, rta) \
+       (parse_rtattr_one(type, RTA_DATA(rta), RTA_PAYLOAD(rta)))
+
 #define parse_rtattr_nested_compat(tb, max, rta, data, len) \
        ({ data = RTA_PAYLOAD(rta) >= len ? RTA_DATA(rta) : NULL;       \
                __parse_rtattr_nested_compat(tb, max, rta, len); })

diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 45ff90a07aa869123555381e94d01fed6e34c528..77e07ef7cf602dd2b18e78e3702da9358088a868 100644 (file)
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -713,6 +713,18 @@ int parse_rtattr_byindex(struct rtattr *tb[], int max, struct rtattr *rta, int l
        return i;
 }
 
+struct rtattr *parse_rtattr_one(int type, struct rtattr *rta, int len)
+{
+       while (RTA_OK(rta, len)) {
+               if (rta->rta_type == type)
+                       return rta;
+               rta = RTA_NEXT(rta, len);
+       }
+       if (len)
+               fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len, rta->rta_len);
+       return NULL;
+}
+
 int __parse_rtattr_nested_compat(struct rtattr *tb[], int max, struct rtattr *rta,
                                 int len)
 {