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

On 7/29/21 3:51 AM, Justin Iurman wrote:

Hi David,

quoted

quoted

+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?

./tc/em_meta.c has print_binary() but it is not json aware.

devlink has pr_out_binary_value which is close. You could probably take
this one and generalize it.

quoted

quoted

+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.

quoted

quoted

+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?

full strcmp.