From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [PATCH iproute2 1/6] ip vrf: Add name_is_vrf
Date: Wed, 29 Jun 2016 08:06:13 -0700
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Cc: netdev@vger.kernel.org
To: David Ahern <dsa@cumulusnetworks.com>
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On Mon, 27 Jun 2016 11:50:56 -0700
David Ahern <dsa@cumulusnetworks.com> wrote:

> diff --git a/ip/ip_common.h b/ip/ip_common.h
> index e8da9e034b15..410eb135774a 100644
> --- a/ip/ip_common.h
> +++ b/ip/ip_common.h
> @@ -90,6 +90,8 @@ struct link_util *get_link_slave_kind(const char *slave_kind);
>  
>  void br_dump_bridge_id(const struct ifla_bridge_id *id, char *buf, size_t len);
>  
> +bool name_is_vrf(char *name);
> +
>  #ifndef	INFINITY_LIFE_TIME
>  #define     INFINITY_LIFE_TIME      0xFFFFFFFFU
>  #endif
> diff --git a/ip/iplink_vrf.c b/ip/iplink_vrf.c
> index e3c7b4652da5..abd43c08423e 100644
> --- a/ip/iplink_vrf.c
> +++ b/ip/iplink_vrf.c
> @@ -96,3 +96,56 @@ struct link_util vrf_slave_link_util = {
>  	.print_opt	= vrf_slave_print_opt,
>  	.slave          = true,
>  };
> +
> +bool name_is_vrf(char *name)

Why not?
bool name_is_vrf(const char *name)

> +{
> +	struct {
> +		struct nlmsghdr		n;
> +		struct ifinfomsg	i;
> +		char			buf[1024];
> +	} req = {
> +		.n = {
> +			.nlmsg_len   = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
> +			.nlmsg_flags = NLM_F_REQUEST,
> +			.nlmsg_type  = RTM_GETLINK,
> +		},
> +		.i = {
> +			.ifi_family  = preferred_family,
> +		},
> +	};
> +	struct {
> +		struct nlmsghdr n;
> +		char buf[8192];
> +	} answer;
> +	struct rtattr *tb[IFLA_MAX+1];
> +	struct rtattr *li[IFLA_INFO_MAX+1];
> +	struct ifinfomsg *ifi;
> +	int len;
> +
> +	addattr_l(&req.n, sizeof(req), IFLA_IFNAME, name, strlen(name) + 1);
> +
> +	if (rtnl_talk(&rth, &req.n, &answer.n, sizeof(answer)) < 0)
> +		goto err;
Just return false instead of all these goto's?
Also you might want to give some indication of error.

> +
> +	ifi = NLMSG_DATA(&answer.n);
> +	len = answer.n.nlmsg_len - NLMSG_LENGTH(sizeof(*ifi));
> +	if (len < 0) {
> +		fprintf(stderr, "BUG: Invalid response to link query.\n");
> +		goto err;
> +	}
> +
> +	parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), len);
> +
> +	if (!tb[IFLA_LINKINFO])
> +		goto err;
> +
> +	parse_rtattr_nested(li, IFLA_INFO_MAX, tb[IFLA_LINKINFO]);
> +
> +	if (!li[IFLA_INFO_KIND])
> +		goto err;
> +
> +	return strcmp(RTA_DATA(li[IFLA_INFO_KIND]), "vrf") == 0;
> +
> +err:
> +	return false;
> +}