Re: [PATCH iproute2-next v2 1/1] iproute: Extend bonding's "arp_ip_target" parameter to add vlan tags.

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 14 Jul 2025 16:05:40 -0700
David Wilder <wilder@us.ibm.com> wrote:

> This change extends the "arp_ip_target" parameter format to allow for
> a list of vlan tags to be included for each arp target.
> 
> The new format for arp_ip_target is:
> arp_ip_target=ipv4-address[vlan-tag\...],...
> 
> Examples:
> arp_ip_target=10.0.0.1[10]
> arp_ip_target=10.0.0.1[100/200]
> 
> The inclusion of a list of vlan tags is optional. The new logic
> preserves both forward and backward compatibility with the kernel
> and iproute2 versions.
> 
> Signed-off-by: David Wilder <wilder@us.ibm.com>
> ---
>  ip/iplink_bond.c | 117 +++++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 108 insertions(+), 9 deletions(-)
> 
> diff --git a/ip/iplink_bond.c b/ip/iplink_bond.c
> index 62dd907c..c4db68a7 100644
> --- a/ip/iplink_bond.c
> +++ b/ip/iplink_bond.c
> @@ -173,6 +173,53 @@ static void explain(void)
>  	print_explain(stderr);
>  }
>  
> +#define BOND_VLAN_PROTO_NONE htons(0xffff)
> +#define BOND_MAX_VLAN_TAGS 5
> +
> +struct bond_vlan_tag {
> +	__be16	vlan_proto;
> +	__be16	vlan_id;
> +};
> +
> +static inline struct bond_vlan_tag *bond_vlan_tags_parse(char *vlan_list, int level, int *size)
No good reason to inline

> +{
> +	struct bond_vlan_tag *tags = NULL;
> +	char *vlan;
> +	int n;
> +
> +	if (level > BOND_MAX_VLAN_TAGS) {
> +		fprintf(stderr,
> +			"Error: Too many vlan tags specified, maximum is %d.\n",
> +			BOND_MAX_VLAN_TAGS);
> +		exit(1);
> +	}
> +
> +	if (!vlan_list || strlen(vlan_list) == 0) {
> +		tags = calloc(level + 1, sizeof(*tags));
> +		*size = (level + 1) * (sizeof(*tags));
> +		if (tags)
> +			tags[level].vlan_proto = BOND_VLAN_PROTO_NONE;
> +		return tags;
> +	}
> +
> +	for (vlan = strsep(&vlan_list, "/"); (vlan != 0); level++) {
> +		tags = bond_vlan_tags_parse(vlan_list, level + 1, size);
> +		if (!tags)
> +			continue;
> +
> +		tags[level].vlan_proto = htons(ETH_P_8021Q);
> +		n = sscanf(vlan, "%hu", &(tags[level].vlan_id));
> +
> +		if (n != 1 || tags[level].vlan_id < 1 ||
> +		    tags[level].vlan_id > 4094)
> +			return NULL;
> +
> +		return tags;
> +	}
> +
> +	return NULL;
> +}
> +
>  static int bond_parse_opt(struct link_util *lu, int argc, char **argv,
>  			  struct nlmsghdr *n)
>  {
> @@ -239,12 +286,29 @@ static int bond_parse_opt(struct link_util *lu, int argc, char **argv,
>  				NEXT_ARG();
>  				char *targets = strdupa(*argv);
>  				char *target = strtok(targets, ",");
> -				int i;
> +				struct bond_vlan_tag *tags;
> +				int size, i;
>  
>  				for (i = 0; target && i < BOND_MAX_ARP_TARGETS; i++) {
> -					__u32 addr = get_addr32(target);
> +					struct Data {
> +						__u32 addr;
> +						struct bond_vlan_tag vlans[];
> +					} data;
> +					char *vlan_list, *dup;
> +
> +					dup = strdupa(target);
> +					data.addr = get_addr32(strsep(&dup, "["));
> +					vlan_list = strsep(&dup, "]");
> +
> +					if (vlan_list) {
> +						tags = bond_vlan_tags_parse(vlan_list, 0, &size);
> +						memcpy(&data.vlans, tags, size);
> +						addattr_l(n, 1024, i, &data,
> +							  sizeof(data.addr)+size);
> +					} else {
> +						addattr32(n, 1024, i, data.addr);
> +					}
>  
> -					addattr32(n, 1024, i, addr);
>  					target = strtok(NULL, ",");
>  				}
>  				addattr_nest_end(n, nest);
> @@ -507,12 +571,47 @@ static void bond_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
>  			print_string(PRINT_FP, NULL, "arp_ip_target ", NULL);
>  		}
>  
> -		for (i = 0; i < BOND_MAX_ARP_TARGETS; i++) {
> -			if (iptb[i])
> -				print_string(PRINT_ANY,
> -					     NULL,
> -					     "%s",
> -					     rt_addr_n2a_rta(AF_INET, iptb[i]));
> +		for (int i = 0; i < BOND_MAX_ARP_TARGETS && iptb[i]; i++) {
> +			struct Data {
> +				__u32 addr;
> +				struct bond_vlan_tag vlans[BOND_MAX_VLAN_TAGS + 1];
> +			} data;
> +
> +			if (RTA_PAYLOAD(iptb[i]) < sizeof(data.addr) ||
> +			    RTA_PAYLOAD(iptb[i]) > sizeof(data)) {
> +				fprintf(stderr, "Internal Error: Bad payload for arp_ip_target.\n");
> +				exit(1);
> +			}
> +			memcpy(&data, RTA_DATA(iptb[i]), RTA_PAYLOAD(iptb[i]));
> +
> +			print_string(PRINT_ANY,
> +				     NULL,
> +				     "%s",
> +				     rt_addr_n2a(AF_INET, sizeof(data.addr), &data.addr));

I know you just moved this line, but can you shorten it, and use print_color_string?

			print_color_string(PRINT_ANY, COLOR_INET, NULL, "%s",
				rt_addr_n2a(AF_INET, sizeof(data.addr), &data_addr));

> +
> +			if (RTA_PAYLOAD(iptb[i]) > sizeof(data.addr) && !is_json_context()) {
> +				print_string(PRINT_ANY, NULL, "[", NULL);
> +
> +				for (int level = 0;

iproute2 follows kernel style and avoids using declaration in for statement

> +				     (data.vlans[level].vlan_proto != BOND_VLAN_PROTO_NONE);

paren not needed for single conditional.

> +				     level++) {
> +
> +					if (level > BOND_MAX_VLAN_TAGS) {
> +						fprintf(stderr,
> +							"Internal Error: too many vlan tags.\n");
> +						exit(1);
> +					}
> +
> +					if (level != 0)
> +						print_string(PRINT_ANY, NULL, "/", NULL);
> +
> +					print_uint(PRINT_ANY,
> +						   NULL, "%u", data.vlans[level].vlan_id);
> +				}
> +
> +				print_string(PRINT_ANY, NULL, "]", NULL);

Did you check the JSON output? Looks like it won't print the tags.

> +			}
> +
>  			if (!is_json_context()
>  			    && i < BOND_MAX_ARP_TARGETS-1
>  			    && iptb[i+1])