Function cc_list_available

freebsd/netinet/cc/cc.c:129–176

* Sysctl handler to display the list of available CC algorithms. */

 * Sysctl handler to display the list of available CC algorithms.
 */
static int
cc_list_available(SYSCTL_HANDLER_ARGS)
{
	struct cc_algo *algo;
	struct sbuf *s;
	int err, first, nalgos;

	err = nalgos = 0;
	first = 1;

	CC_LIST_RLOCK();
	STAILQ_FOREACH(algo, &cc_list, entries) {
		nalgos++;
	}
	CC_LIST_RUNLOCK();

	s = sbuf_new(NULL, NULL, nalgos * TCP_CA_NAME_MAX, SBUF_FIXEDLEN);

	if (s == NULL)
		return (ENOMEM);

	/*
	 * It is theoretically possible for the CC list to have grown in size
	 * since the call to sbuf_new() and therefore for the sbuf to be too
	 * small. If this were to happen (incredibly unlikely), the sbuf will
	 * reach an overflow condition, sbuf_printf() will return an error and
	 * the sysctl will fail gracefully.
	 */
	CC_LIST_RLOCK();
	STAILQ_FOREACH(algo, &cc_list, entries) {
		err = sbuf_printf(s, first ? "%s" : ", %s", algo->name);
		if (err) {
			/* Sbuf overflow condition. */
			err = EOVERFLOW;
			break;
		}
		first = 0;
	}
	CC_LIST_RUNLOCK();

	if (!err) {
		sbuf_finish(s);
		err = sysctl_handle_string(oidp, sbuf_data(s), 0, req);
	}

	sbuf_delete(s);
	return (err);
}

/*
 * Reset the default CC algo to NewReno for any netstack which is using the algo