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From:   Johannes Berg <johannes@sipsolutions.net>
To:     linux-wireless@vger.kernel.org,
        Stephen Hemminger <stephen@networkplumber.org>,
        netdev@vger.kernel.org
Cc:     David Ahern <dsahern@gmail.com>
Subject: [PATCH 1/3] libnetlink: add rtattr_for_each_nested() iteration macro
Date:   Mon, 24 Aug 2020 19:51:06 +0200
Message-Id: <20200824175108.53101-1-johannes@sipsolutions.net>
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Sender: linux-wireless-owner@vger.kernel.org
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This is useful for iterating elements in a nested attribute,
if they're not parsed with a strict length limit or such.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
---
 include/libnetlink.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/libnetlink.h b/include/libnetlink.h
index e27516f7648f..0d4a9f29afbd 100644
--- a/include/libnetlink.h
+++ b/include/libnetlink.h
@@ -284,4 +284,9 @@ int rtnl_from_file(FILE *, rtnl_listen_filter_t handler,
  * messages from dump file */
 #define NLMSG_TSTAMP	15
 
+#define rtattr_for_each_nested(attr, nest) \
+	for ((attr) = (void *)RTA_DATA(nest); \
+	     RTA_OK(attr, RTA_PAYLOAD(nest) - ((char *)(attr) - (char *)RTA_DATA((nest)))); \
+	     (attr) = RTA_TAIL((attr)))
+
 #endif /* __LIBNETLINK_H__ */
-- 
2.26.2