netdev - Re: [RFC iproute2-next 03/11] ip: nexthop: add nh struct and a helper to parse nhmsg into it

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Date:   Wed, 29 Sep 2021 21:33:47 -0600
From:   David Ahern <dsahern@...il.com>
To:     Nikolay Aleksandrov <razor@...ckwall.org>, netdev@...r.kernel.org
Cc:     roopa@...dia.com, donaldsharp72@...il.com, idosch@...sch.org,
        Nikolay Aleksandrov <nikolay@...dia.com>
Subject: Re: [RFC iproute2-next 03/11] ip: nexthop: add nh struct and a helper
 to parse nhmsg into it

On 9/29/21 9:28 AM, Nikolay Aleksandrov wrote:
> @@ -328,6 +336,93 @@ static void print_nh_res_bucket(FILE *fp, const struct rtattr *res_bucket_attr)
>  	close_json_object();
>  }
>  
> +static void ipnh_destroy_entry(struct nh_entry *nhe)
> +{
> +	if (nhe->nh_encap)
> +		free(nhe->nh_encap);
> +	if (nhe->nh_groups)
> +		free(nhe->nh_groups);
> +}
> +
> +/* parse nhmsg into nexthop entry struct which must be destroyed by
> + * ipnh_destroy_enty when it's not needed anymore
> + */

I'd rather not have 2 functions interpreting the attributes. You should
be able to get print_nexthop to use the parse function and then print
using the nh_entry.


> +static int ipnh_parse_nhmsg(FILE *fp, const struct nhmsg *nhm, int len,
> +			    struct nh_entry *nhe)
> +{
> +	struct rtattr *tb[NHA_MAX+1];
> +	int err = 0;
> +
> +	memset(nhe, 0, sizeof(*nhe));
> +	parse_rtattr_flags(tb, NHA_MAX, RTM_NHA(nhm), len, NLA_F_NESTED);
> +
> +	if (tb[NHA_ID])
> +		nhe->nh_id = rta_getattr_u32(tb[NHA_ID]);
> +
> +	if (tb[NHA_OIF])
> +		nhe->nh_oif = rta_getattr_u32(tb[NHA_OIF]);
> +
> +	if (tb[NHA_GROUP_TYPE])
> +		nhe->nh_grp_type = rta_getattr_u16(tb[NHA_GROUP_TYPE]);
> +
> +	if (tb[NHA_GATEWAY]) {
> +		if (RTA_PAYLOAD(tb[NHA_GATEWAY]) > sizeof(nhe->nh_gateway)) {
> +			fprintf(fp, "<nexthop id %u invalid gateway length %lu>\n",
> +				nhe->nh_id, RTA_PAYLOAD(tb[NHA_GATEWAY]));
> +			err = EINVAL;
> +			goto out_err;
> +		}
> +		nhe->nh_gateway_len = RTA_PAYLOAD(tb[NHA_GATEWAY]);
> +		memcpy(&nhe->nh_gateway, RTA_DATA(tb[NHA_GATEWAY]),
> +		       RTA_PAYLOAD(tb[NHA_GATEWAY]));
> +	}
> +
> +	if (tb[NHA_ENCAP]) {
> +		nhe->nh_encap = malloc(RTA_LENGTH(RTA_PAYLOAD(tb[NHA_ENCAP])));
> +		if (!nhe->nh_encap) {
> +			err = ENOMEM;
> +			goto out_err;
> +		}
> +		memcpy(nhe->nh_encap, tb[NHA_ENCAP],
> +		       RTA_LENGTH(RTA_PAYLOAD(tb[NHA_ENCAP])));
> +		memcpy(&nhe->nh_encap_type, tb[NHA_ENCAP_TYPE],
> +		       sizeof(nhe->nh_encap_type));
> +	}
> +
> +	if (tb[NHA_GROUP]) {
> +		if (!__valid_nh_group_attr(tb[NHA_GROUP])) {
> +			fprintf(fp, "<nexthop id %u invalid nexthop group>",
> +				nhe->nh_id);
> +			err = EINVAL;
> +			goto out_err;
> +		}
> +
> +		nhe->nh_groups = malloc(RTA_PAYLOAD(tb[NHA_GROUP]));
> +		if (!nhe->nh_groups) {
> +			err = ENOMEM;
> +			goto out_err;
> +		}
> +		nhe->nh_groups_cnt = RTA_PAYLOAD(tb[NHA_GROUP]) /
> +				     sizeof(struct nexthop_grp);
> +		memcpy(nhe->nh_groups, RTA_DATA(tb[NHA_GROUP]),
> +		       RTA_PAYLOAD(tb[NHA_GROUP]));
> +	}
> +
> +	nhe->nh_blackhole = !!tb[NHA_BLACKHOLE];
> +	nhe->nh_fdb = !!tb[NHA_FDB];
> +
> +	nhe->nh_family = nhm->nh_family;
> +	nhe->nh_protocol = nhm->nh_protocol;
> +	nhe->nh_scope = nhm->nh_scope;
> +	nhe->nh_flags = nhm->nh_flags;
> +
> +	return 0;
> +
> +out_err:
> +	ipnh_destroy_entry(nhe);
> +	return err;
> +}
> +