+/* 7.1.24. Delayed Ack Timer (SCTP_DELAYED_ACK_TIME)
+ *
+ * This options will get or set the delayed ack timer. The time is set
+ * in milliseconds. If the assoc_id is 0, then this sets or gets the
+ * endpoints default delayed ack timer value. If the assoc_id field is
+ * non-zero, then the set or get effects the specified association.
+ *
+ * struct sctp_assoc_value {
+ * sctp_assoc_t assoc_id;
+ * uint32_t assoc_value;
+ * };
+ *
+ * assoc_id - This parameter, indicates which association the
+ * user is preforming an action upon. Note that if
+ * this field's value is zero then the endpoints
+ * default value is changed (effecting future
+ * associations only).
+ *
+ * assoc_value - This parameter contains the number of milliseconds
+ * that the user is requesting the delayed ACK timer
+ * be set to. Note that this value is defined in
+ * the standard to be between 200 and 500 milliseconds.
+ *
+ * Note: a value of zero will leave the value alone,
+ * but disable SACK delay. A non-zero value will also
+ * enable SACK delay.
+ */
+
+static int sctp_setsockopt_delayed_ack_time(struct sock *sk,
+ char __user *optval, int optlen)
+{
+ struct sctp_assoc_value params;
+ struct sctp_transport *trans = NULL;
+ struct sctp_association *asoc = NULL;
+ struct sctp_sock *sp = sctp_sk(sk);
+
+ if (optlen != sizeof(struct sctp_assoc_value))
+ return - EINVAL;
+
+ if (copy_from_user(¶ms, optval, optlen))
+ return -EFAULT;
+
+ /* Validate value parameter. */
+ if (params.assoc_value > 500)
+ return -EINVAL;
+
+ /* Get association, if assoc_id != 0 and the socket is a one
+ * to many style socket, and an association was not found, then
+ * the id was invalid.
+ */
+ asoc = sctp_id2assoc(sk, params.assoc_id);
+ if (!asoc && params.assoc_id && sctp_style(sk, UDP))
+ return -EINVAL;
+
+ if (params.assoc_value) {
+ if (asoc) {
+ asoc->sackdelay =
+ msecs_to_jiffies(params.assoc_value);
+ asoc->param_flags =
+ (asoc->param_flags & ~SPP_SACKDELAY) |
+ SPP_SACKDELAY_ENABLE;
+ } else {
+ sp->sackdelay = params.assoc_value;
+ sp->param_flags =
+ (sp->param_flags & ~SPP_SACKDELAY) |
+ SPP_SACKDELAY_ENABLE;
+ }
+ } else {
+ if (asoc) {
+ asoc->param_flags =
+ (asoc->param_flags & ~SPP_SACKDELAY) |
+ SPP_SACKDELAY_DISABLE;
+ } else {
+ sp->param_flags =
+ (sp->param_flags & ~SPP_SACKDELAY) |
+ SPP_SACKDELAY_DISABLE;
+ }
+ }
+
+ /* If change is for association, also apply to each transport. */
+ if (asoc) {
+ struct list_head *pos;
+
+ list_for_each(pos, &asoc->peer.transport_addr_list) {
+ trans = list_entry(pos, struct sctp_transport,
+ transports);
+ if (params.assoc_value) {
+ trans->sackdelay =
+ msecs_to_jiffies(params.assoc_value);
+ trans->param_flags =
+ (trans->param_flags & ~SPP_SACKDELAY) |
+ SPP_SACKDELAY_ENABLE;
+ } else {
+ trans->param_flags =
+ (trans->param_flags & ~SPP_SACKDELAY) |
+ SPP_SACKDELAY_DISABLE;
+ }
+ }
+ }
+
+ return 0;
+}
+