Fix attribute list size in do_get_nl_link()

The function do_get_nl_link() retrieves attributes from the response
RTM_NEWLINK. But it calculates the attribute list size with the wrong
structure struct ifaddrmsg. According to man 7 rtnetlink, RTM_NEWLINK
message uses struct ifinfomsg instead of struct ifaddrmsg.  This causes
that additional 8 bytes are parsed and garbage attributes might be
retrieved. One of consequences is that the message will be dropped if
the garbage attribute is IFLA_IFNAME and contains an invalid interface
name.

To fix this issue, use struct ifinfomsg to calculate the size of
attribute list for RTM_NEWLINK.

Signed-off-by: Wang Xin <xin.wang7@cn.bosch.com>
Signed-off-by: Mark Jonas <mark.jonas@de.bosch.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Author: Wang Xin

src/libsocketcan.c

@@ -411,7 +411,7 @@ static int do_get_nl_link(int fd, __u8 acquire, const char *name, void *res)
 			struct rtattr *tb[IFLA_MAX + 1];
 
 			len =
-				nl_msg->nlmsg_len - NLMSG_LENGTH(sizeof(struct ifaddrmsg));
+				nl_msg->nlmsg_len - NLMSG_LENGTH(sizeof(struct ifinfomsg));
 			parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), len);
 
 			/* Finish process if the reply message is matched */