llc_c_ac.c

linux 内核源代码

		llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
				    llc->daddr.lsap, LLC_PDU_RSP);
		llc_pdu_init_as_rr_rsp(nskb, llc->ack_pf, llc->vR);
		rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
		if (unlikely(rc))
			goto free;
		llc_conn_send_pdu(sk, nskb);
	}
out:
	return rc;
free:
	kfree_skb(nskb);
	goto out;
}

/**
 *	llc_conn_ac_inc_npta_value - tries to make value of npta greater
 *	@sk: current connection structure.
 *	@skb: current event.
 *
 *	After "inc_cntr" times calling of this action, "npta" increase by one.
 *	this action tries to make vale of "npta" greater as possible; number of
 *	acknowledgements decreases by increasing of "npta". Returns 0 for
 *	success, 1 otherwise.
 */
static int llc_conn_ac_inc_npta_value(struct sock *sk, struct sk_buff *skb)
{
	struct llc_sock *llc = llc_sk(sk);

	if (!llc->inc_cntr) {
		llc->dec_step = 0;
		llc->dec_cntr = llc->inc_cntr = 2;
		++llc->npta;
		if (llc->npta > (u8) ~LLC_2_SEQ_NBR_MODULO)
			llc->npta = (u8) ~LLC_2_SEQ_NBR_MODULO;
	} else
		--llc->inc_cntr;
	return 0;
}

/**
 *	llc_conn_ac_adjust_npta_by_rr - decreases "npta" by one
 *	@sk: current connection structure.
 *	@skb: current event.
 *
 *	After receiving "dec_cntr" times RR command, this action decreases
 *	"npta" by one. Returns 0 for success, 1 otherwise.
 */
int llc_conn_ac_adjust_npta_by_rr(struct sock *sk, struct sk_buff *skb)
{
	struct llc_sock *llc = llc_sk(sk);

	if (!llc->connect_step && !llc->remote_busy_flag) {
		if (!llc->dec_step) {
			if (!llc->dec_cntr) {
				llc->inc_cntr = llc->dec_cntr = 2;
				if (llc->npta > 0)
					llc->npta = llc->npta - 1;
			} else
				llc->dec_cntr -=1;
		}
	} else
		llc->connect_step = 0 ;
	return 0;
}

/**
 *	llc_conn_ac_adjust_npta_by_rnr - decreases "npta" by one
 *	@sk: current connection structure.
 *	@skb: current event.
 *
 *	After receiving "dec_cntr" times RNR command, this action decreases
 *	"npta" by one. Returns 0 for success, 1 otherwise.
 */
int llc_conn_ac_adjust_npta_by_rnr(struct sock *sk, struct sk_buff *skb)
{
	struct llc_sock *llc = llc_sk(sk);

	if (llc->remote_busy_flag)
		if (!llc->dec_step) {
			if (!llc->dec_cntr) {
				llc->inc_cntr = llc->dec_cntr = 2;
				if (llc->npta > 0)
					--llc->npta;
			} else
				--llc->dec_cntr;
		}
	return 0;
}

/**
 *	llc_conn_ac_dec_tx_win_size - decreases tx window size
 *	@sk: current connection structure.
 *	@skb: current event.
 *
 *	After receiving of a REJ command or response, transmit window size is
 *	decreased by number of PDUs which are outstanding yet. Returns 0 for
 *	success, 1 otherwise.
 */
int llc_conn_ac_dec_tx_win_size(struct sock *sk, struct sk_buff *skb)
{
	struct llc_sock *llc = llc_sk(sk);
	u8 unacked_pdu = skb_queue_len(&llc->pdu_unack_q);

	if (llc->k - unacked_pdu < 1)
		llc->k = 1;
	else
		llc->k -= unacked_pdu;
	return 0;
}

/**
 *	llc_conn_ac_inc_tx_win_size - tx window size is inc by 1
 *	@sk: current connection structure.
 *	@skb: current event.
 *
 *	After receiving an RR response with f-bit set to one, transmit window
 *	size is increased by one. Returns 0 for success, 1 otherwise.
 */
int llc_conn_ac_inc_tx_win_size(struct sock *sk, struct sk_buff *skb)
{
	struct llc_sock *llc = llc_sk(sk);

	llc->k += 1;
	if (llc->k > (u8) ~LLC_2_SEQ_NBR_MODULO)
		llc->k = (u8) ~LLC_2_SEQ_NBR_MODULO;
	return 0;
}

int llc_conn_ac_stop_all_timers(struct sock *sk, struct sk_buff *skb)
{
	struct llc_sock *llc = llc_sk(sk);

	del_timer(&llc->pf_cycle_timer.timer);
	del_timer(&llc->ack_timer.timer);
	del_timer(&llc->rej_sent_timer.timer);
	del_timer(&llc->busy_state_timer.timer);
	llc->ack_must_be_send = 0;
	llc->ack_pf = 0;
	return 0;
}

int llc_conn_ac_stop_other_timers(struct sock *sk, struct sk_buff *skb)
{
	struct llc_sock *llc = llc_sk(sk);

	del_timer(&llc->rej_sent_timer.timer);
	del_timer(&llc->pf_cycle_timer.timer);
	del_timer(&llc->busy_state_timer.timer);
	llc->ack_must_be_send = 0;
	llc->ack_pf = 0;
	return 0;
}

int llc_conn_ac_start_ack_timer(struct sock *sk, struct sk_buff *skb)
{
	struct llc_sock *llc = llc_sk(sk);

	mod_timer(&llc->ack_timer.timer, jiffies + llc->ack_timer.expire);
	return 0;
}

int llc_conn_ac_start_rej_timer(struct sock *sk, struct sk_buff *skb)
{
	struct llc_sock *llc = llc_sk(sk);

	mod_timer(&llc->rej_sent_timer.timer,
		  jiffies + llc->rej_sent_timer.expire);
	return 0;
}

int llc_conn_ac_start_ack_tmr_if_not_running(struct sock *sk,
					     struct sk_buff *skb)
{
	struct llc_sock *llc = llc_sk(sk);

	if (!timer_pending(&llc->ack_timer.timer))
		mod_timer(&llc->ack_timer.timer,
			  jiffies + llc->ack_timer.expire);
	return 0;
}

int llc_conn_ac_stop_ack_timer(struct sock *sk, struct sk_buff *skb)
{
	del_timer(&llc_sk(sk)->ack_timer.timer);
	return 0;
}

int llc_conn_ac_stop_p_timer(struct sock *sk, struct sk_buff *skb)
{
	struct llc_sock *llc = llc_sk(sk);

	del_timer(&llc->pf_cycle_timer.timer);
	llc_conn_set_p_flag(sk, 0);
	return 0;
}

int llc_conn_ac_stop_rej_timer(struct sock *sk, struct sk_buff *skb)
{
	del_timer(&llc_sk(sk)->rej_sent_timer.timer);
	return 0;
}

int llc_conn_ac_upd_nr_received(struct sock *sk, struct sk_buff *skb)
{
	int acked;
	u16 unacked = 0;
	struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
	struct llc_sock *llc = llc_sk(sk);

	llc->last_nr = PDU_SUPV_GET_Nr(pdu);
	acked = llc_conn_remove_acked_pdus(sk, llc->last_nr, &unacked);
	/* On loopback we don't queue I frames in unack_pdu_q queue. */
	if (acked > 0 || (llc->dev->flags & IFF_LOOPBACK)) {
		llc->retry_count = 0;
		del_timer(&llc->ack_timer.timer);
		if (llc->failed_data_req) {
			/* already, we did not accept data from upper layer
			 * (tx_window full or unacceptable state). Now, we
			 * can send data and must inform to upper layer.
			 */
			llc->failed_data_req = 0;
			llc_conn_ac_data_confirm(sk, skb);
		}
		if (unacked)
			mod_timer(&llc->ack_timer.timer,
				  jiffies + llc->ack_timer.expire);
	} else if (llc->failed_data_req) {
		u8 f_bit;

		llc_pdu_decode_pf_bit(skb, &f_bit);
		if (f_bit == 1) {
			llc->failed_data_req = 0;
			llc_conn_ac_data_confirm(sk, skb);
		}
	}
	return 0;
}

int llc_conn_ac_upd_p_flag(struct sock *sk, struct sk_buff *skb)
{
	struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);

	if (LLC_PDU_IS_RSP(pdu)) {
		u8 f_bit;

		llc_pdu_decode_pf_bit(skb, &f_bit);
		if (f_bit) {
			llc_conn_set_p_flag(sk, 0);
			llc_conn_ac_stop_p_timer(sk, skb);
		}
	}
	return 0;
}

int llc_conn_ac_set_data_flag_2(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->data_flag = 2;
	return 0;
}

int llc_conn_ac_set_data_flag_0(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->data_flag = 0;
	return 0;
}

int llc_conn_ac_set_data_flag_1(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->data_flag = 1;
	return 0;
}

int llc_conn_ac_set_data_flag_1_if_data_flag_eq_0(struct sock *sk,
						  struct sk_buff *skb)
{
	if (!llc_sk(sk)->data_flag)
		llc_sk(sk)->data_flag = 1;
	return 0;
}

int llc_conn_ac_set_p_flag_0(struct sock *sk, struct sk_buff *skb)
{
	llc_conn_set_p_flag(sk, 0);
	return 0;
}

static int llc_conn_ac_set_p_flag_1(struct sock *sk, struct sk_buff *skb)
{
	llc_conn_set_p_flag(sk, 1);
	return 0;
}

int llc_conn_ac_set_remote_busy_0(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->remote_busy_flag = 0;
	return 0;
}

int llc_conn_ac_set_cause_flag_0(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->cause_flag = 0;
	return 0;
}

int llc_conn_ac_set_cause_flag_1(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->cause_flag = 1;
	return 0;
}

int llc_conn_ac_set_retry_cnt_0(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->retry_count = 0;
	return 0;
}

int llc_conn_ac_inc_retry_cnt_by_1(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->retry_count++;
	return 0;
}

int llc_conn_ac_set_vr_0(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->vR = 0;
	return 0;
}

int llc_conn_ac_inc_vr_by_1(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->vR = PDU_GET_NEXT_Vr(llc_sk(sk)->vR);
	return 0;
}

int llc_conn_ac_set_vs_0(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->vS = 0;
	return 0;
}

int llc_conn_ac_set_vs_nr(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->vS = llc_sk(sk)->last_nr;
	return 0;
}

static int llc_conn_ac_inc_vs_by_1(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->vS = (llc_sk(sk)->vS + 1) % LLC_2_SEQ_NBR_MODULO;
	return 0;
}

static void llc_conn_tmr_common_cb(unsigned long timeout_data, u8 type)
{
	struct sock *sk = (struct sock *)timeout_data;
	struct sk_buff *skb = alloc_skb(0, GFP_ATOMIC);

	bh_lock_sock(sk);
	if (skb) {
		struct llc_conn_state_ev *ev = llc_conn_ev(skb);

		skb_set_owner_r(skb, sk);
		ev->type = type;
		llc_process_tmr_ev(sk, skb);
	}
	bh_unlock_sock(sk);
}

void llc_conn_pf_cycle_tmr_cb(unsigned long timeout_data)
{
	llc_conn_tmr_common_cb(timeout_data, LLC_CONN_EV_TYPE_P_TMR);
}

void llc_conn_busy_tmr_cb(unsigned long timeout_data)
{
	llc_conn_tmr_common_cb(timeout_data, LLC_CONN_EV_TYPE_BUSY_TMR);
}

void llc_conn_ack_tmr_cb(unsigned long timeout_data)
{
	llc_conn_tmr_common_cb(timeout_data, LLC_CONN_EV_TYPE_ACK_TMR);
}

void llc_conn_rej_tmr_cb(unsigned long timeout_data)
{
	llc_conn_tmr_common_cb(timeout_data, LLC_CONN_EV_TYPE_REJ_TMR);
}

int llc_conn_ac_rst_vs(struct sock *sk, struct sk_buff *skb)
{
	llc_sk(sk)->X = llc_sk(sk)->vS;
	llc_conn_ac_set_vs_nr(sk, skb);
	return 0;
}

int llc_conn_ac_upd_vs(struct sock *sk, struct sk_buff *skb)
{
	struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
	u8 nr = PDU_SUPV_GET_Nr(pdu);

	if (llc_circular_between(llc_sk(sk)->vS, nr, llc_sk(sk)->X))
		llc_conn_ac_set_vs_nr(sk, skb);
	return 0;
}

/*
 * Non-standard actions; these not contained in IEEE specification; for
 * our own usage
 */
/**
 *	llc_conn_disc - removes connection from SAP list and frees it
 *	@sk: closed connection
 *	@skb: occurred event
 */
int llc_conn_disc(struct sock *sk, struct sk_buff *skb)
{
	/* FIXME: this thing seems to want to die */
	return 0;
}

/**
 *	llc_conn_reset - resets connection
 *	@sk : reseting connection.
 *	@skb: occurred event.
 *
 *	Stop all timers, empty all queues and reset all flags.
 */
int llc_conn_reset(struct sock *sk, struct sk_buff *skb)
{
	llc_sk_reset(sk);
	return 0;
}

/**
 *	llc_circular_between - designates that b is between a and c or not
 *	@a: lower bound
 *	@b: element to see if is between a and b
 *	@c: upper bound
 *
 *	This function designates that b is between a and c or not (for example,
 *	0 is between 127 and 1). Returns 1 if b is between a and c, 0
 *	otherwise.
 */
u8 llc_circular_between(u8 a, u8 b, u8 c)
{
	b = b - a;
	c = c - a;
	return b <= c;
}

/**
 *	llc_process_tmr_ev - timer backend
 *	@sk: active connection
 *	@skb: occurred event
 *
 *	This function is called from timer callback functions. When connection
 *	is busy (during sending a data frame) timer expiration event must be
 *	queued. Otherwise this event can be sent to connection state machine.
 *	Queued events will process by llc_backlog_rcv function after sending
 *	data frame.
 */
static void llc_process_tmr_ev(struct sock *sk, struct sk_buff *skb)
{
	if (llc_sk(sk)->state == LLC_CONN_OUT_OF_SVC) {
		printk(KERN_WARNING "%s: timer called on closed connection\n",
		       __FUNCTION__);
		kfree_skb(skb);
	} else {
		if (!sock_owned_by_user(sk))
			llc_conn_state_process(sk, skb);
		else {
			llc_set_backlog_type(skb, LLC_EVENT);
			sk_add_backlog(sk, skb);
		}
	}
}