netdev - Re: [PATCH iproute2-next v2 1/3] Add, show, link, remove IOAM namespaces and schemas

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Message-ID: <506325411.28069607.1627552295593.JavaMail.zimbra@uliege.be>
Date:   Thu, 29 Jul 2021 11:51:35 +0200 (CEST)
From:   Justin Iurman <justin.iurman@...ege.be>
To:     David Ahern <dsahern@...il.com>
Cc:     netdev@...r.kernel.org, stephen@...workplumber.org
Subject: Re: [PATCH iproute2-next v2 1/3] Add, show, link, remove IOAM
 namespaces and schemas

Hi David,

>> +static void print_schema(struct rtattr *attrs[])
>> +{
>> +	__u8 data[IOAM6_MAX_SCHEMA_DATA_LEN + 1];
>> +	int len;
>> +
>> +	print_uint(PRINT_ANY, "schema", "schema %u",
>> +		   rta_getattr_u32(attrs[IOAM6_ATTR_SC_ID]));
>> +
>> +	if (attrs[IOAM6_ATTR_NS_ID])
>> +		print_uint(PRINT_ANY, "namespace", " [namespace %u]",
>> +			   rta_getattr_u16(attrs[IOAM6_ATTR_NS_ID]));
>> +
>> +	len = RTA_PAYLOAD(attrs[IOAM6_ATTR_SC_DATA]);
>> +	memcpy(data, RTA_DATA(attrs[IOAM6_ATTR_SC_DATA]), len);
>> +	data[len] = '\0';
>> +
>> +	print_string(PRINT_ANY, "data", ", data \"%s\"", (const char *)data);
> 
> The attribute descriptions shows this as binary data, not a string.

Indeed. Maybe should I print it as hex... What do you think is more appropriate for this?


>> +static int ioam6_do_cmd(void)
>> +{
>> +	IOAM6_REQUEST(req, 1036, opts.cmd, NLM_F_REQUEST);
>> +	int dump = 0;
>> +
>> +	if (genl_family < 0) {
>> +		if (rtnl_open_byproto(&grth, 0, NETLINK_GENERIC) < 0) {
>> +			fprintf(stderr, "Cannot open generic netlink socket\n");
>> +			exit(1);
>> +		}
>> +		genl_family = genl_resolve_family(&grth, IOAM6_GENL_NAME);
> 
> The above 2 calls can be done with genl_init_handle.

Didn't know that one, thx for the pointer.


>> +int do_ioam6(int argc, char **argv)
>> +{
>> +	bool maybe_wide = false;
>> +
>> +	if (argc < 1 || matches(*argv, "help") == 0)
>> +		usage();
>> +
>> +	memset(&opts, 0, sizeof(opts));
>> +
>> +	if (matches(*argv, "namespace") == 0) {
> 
> matches has been shown to be quite frail. Convenient for shorthand
> typing commands, but frail in the big picture. We should stop using it -
> especially for new commands.

Sure. What do you suggest as an alternative?