netdev - Re: [PATCH iproute2] ip: Properly display AF_BRIDGE address information for neighbor events

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Date:   Fri, 23 Feb 2018 08:28:42 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Donald Sharp <sharpd@...ulusnetworks.com>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH iproute2] ip: Properly display AF_BRIDGE address
 information for neighbor events

On Wed, 21 Feb 2018 21:26:50 -0500
Donald Sharp <sharpd@...ulusnetworks.com> wrote:

> The vxlan driver when a neighbor add/delete event occurs sends
> NDA_DST filled with a union:
> 
> union vxlan_addr {
> 	struct sockaddr_in sin;
> 	struct sockaddr_in6 sin6;
> 	struct sockaddr sa;
> };
> 
> This eventually calls rt_addr_n2a_r which had no handler for the
> AF_BRIDGE family and "???" was being printed.
> 
> Add code to properly display this data when requested.
> 
> Signed-off-by: Donald Sharp <sharpd@...ulusnetworks.com>

Minor style comment.

> ---
>  lib/utils.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/lib/utils.c b/lib/utils.c
> index 24aeddd8..e01e18a7 100644
> --- a/lib/utils.c
> +++ b/lib/utils.c
> @@ -1004,6 +1004,24 @@ const char *rt_addr_n2a_r(int af, int len,
>  	}
>  	case AF_PACKET:
>  		return ll_addr_n2a(addr, len, ARPHRD_VOID, buf, buflen);
> +	case AF_BRIDGE:
> +	{
> +		unsigned short family = ((struct sockaddr *)addr)->sa_family;
> +		struct sockaddr_in6 *sin6;
> +		struct sockaddr_in *sin;
> +

Since you are doing aliasing, would it be clearer to do?
		union {
			struct sockaddr sa;
			struct sockaddr_in6 sin6;
			struct sockaddr_in sin;
		} *sa = addr;

> +		switch(family) {
> +		case AF_INET:
> +			sin = (struct sockaddr_in *)addr;
Casting a void pointer is unnecessary

> +			return inet_ntop(AF_INET, &sin->sin_addr, buf, buflen);
> +		case AF_INET6:
> +			sin6 = (struct sockaddr_in6 *)addr;
> +			return inet_ntop(AF_INET6, &sin6->sin6_addr,
> +					 buf, buflen);
> +		}
> +
> +		/* fallthrough */
> +	}
>  	default:
>  		return "???";
>  	}