/**
* llc_conn_resend_i_pdu_as_rsp - Resend all unacknowledged I PDUs
* @sk: active connection.
* @nr: NR
* @first_f_bit: f_bit value of first pdu.
*
* Resend all unacknowledged I PDUs, starting with the NR; send first as
* response PDU with F bit equal first_f_bit; if more than one send
* subsequent as response PDUs with F bit equal zero (0).
*/
void llc_conn_resend_i_pdu_as_rsp(struct sock *sk, u8 nr, u8 first_f_bit)
{
struct sk_buff *skb;
u16 nbr_unack_pdus;
struct llc_sock *llc = llc_sk(sk);
u8 howmany_resend = 0;
llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
if (!nbr_unack_pdus)
goto out;
/*
* Process unack PDUs only if unack queue is not empty; remove
* appropriate PDUs, fix them up, and put them on mac_pdu_q
*/
while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
llc_pdu_set_cmd_rsp(skb, LLC_PDU_RSP);
llc_pdu_set_pf_bit(skb, first_f_bit);
skb_queue_tail(&sk->sk_write_queue, skb);
first_f_bit = 0;
llc->vS = LLC_I_GET_NS(pdu);
howmany_resend++;
}
if (howmany_resend > 0)
llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
/* any PDUs to re-send are queued up; start sending to MAC */
llc_conn_send_pdus(sk);
out:;
}
/**
* llc_conn_remove_acked_pdus - Removes acknowledged pdus from tx queue
* @sk: active connection
* nr: NR
* how_many_unacked: size of pdu_unack_q after removing acked pdus
*
* Removes acknowledged pdus from transmit queue (pdu_unack_q). Returns
* the number of pdus that removed from queue.
*/
int llc_conn_remove_acked_pdus(struct sock *sk, u8 nr, u16 *how_many_unacked)
{
int pdu_pos, i;
struct sk_buff *skb;
struct llc_pdu_sn *pdu;
int nbr_acked = 0;
struct llc_sock *llc = llc_sk(sk);
int q_len = skb_queue_len(&llc->pdu_unack_q);
if (!q_len)
goto out;
skb = skb_peek(&llc->pdu_unack_q);
pdu = llc_pdu_sn_hdr(skb);
/* finding position of last acked pdu in queue */
pdu_pos = ((int)LLC_2_SEQ_NBR_MODULO + (int)nr -
(int)LLC_I_GET_NS(pdu)) % LLC_2_SEQ_NBR_MODULO;
for (i = 0; i < pdu_pos && i < q_len; i++) {
skb = skb_dequeue(&llc->pdu_unack_q);
kfree_skb(skb);
nbr_acked++;
}
out:
*how_many_unacked = skb_queue_len(&llc->pdu_unack_q);
return nbr_acked;
}
void llc_conn_resend_i_pdu_as_rsp(struct sock *sk, u8 nr, u8 first_f_bit)
{
struct sk_buff *skb;
u16 nbr_unack_pdus;
struct llc_sock *llc = llc_sk(sk);
u8 howmany_resend = 0;
llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
if (!nbr_unack_pdus)
goto out;
while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
llc_pdu_set_cmd_rsp(skb, LLC_PDU_RSP);
llc_pdu_set_pf_bit(skb, first_f_bit);
skb_queue_tail(&sk->sk_write_queue, skb);
first_f_bit = 0;
llc->vS = LLC_I_GET_NS(pdu);
howmany_resend++;
}
if (howmany_resend > 0)
llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
llc_conn_send_pdus(sk);
out:;
}
int llc_conn_ev_rx_i_rsp_fbit_set_x(struct sock *sk, struct sk_buff *skb)
{
struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
return llc_conn_space(sk, skb) &&
LLC_PDU_IS_RSP(pdu) && LLC_PDU_TYPE_IS_I(pdu) &&
LLC_I_GET_NS(pdu) == llc_sk(sk)->vR ? 0 : 1;
}
int llc_conn_ev_rx_i_cmd_pbit_set_1(struct sock *sk, struct sk_buff *skb)
{
struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
return llc_conn_space(sk, skb) &&
LLC_PDU_IS_CMD(pdu) && LLC_PDU_TYPE_IS_I(pdu) &&
LLC_I_PF_IS_1(pdu) &&
LLC_I_GET_NS(pdu) == llc_sk(sk)->vR ? 0 : 1;
}
int llc_conn_ev_rx_i_rsp_fbit_set_x_unexpd_ns(struct sock *sk,
struct sk_buff *skb)
{
struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
u8 vr = llc_sk(sk)->vR;
u8 ns = LLC_I_GET_NS(pdu);
return LLC_PDU_IS_RSP(pdu) && LLC_PDU_TYPE_IS_I(pdu) && ns != vr &&
!llc_util_ns_inside_rx_window(ns, vr, llc_sk(sk)->rw) ? 0 : 1;
}
int llc_conn_ev_rx_i_cmd_pbit_set_1_unexpd_ns(struct sock *sk,
struct sk_buff *skb)
{
const struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
const u8 vr = llc_sk(sk)->vR;
const u8 ns = LLC_I_GET_NS(pdu);
return LLC_PDU_IS_CMD(pdu) && LLC_PDU_TYPE_IS_I(pdu) &&
LLC_I_PF_IS_1(pdu) && ns != vr &&
!llc_util_ns_inside_rx_window(ns, vr, llc_sk(sk)->rw) ? 0 : 1;
}
int llc_conn_ev_rx_i_rsp_fbit_set_x_inval_ns(struct sock *sk,
struct sk_buff *skb)
{
struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
u8 vr = llc_sk(sk)->vR;
u8 ns = LLC_I_GET_NS(pdu);
u16 rc = LLC_PDU_IS_RSP(pdu) && LLC_PDU_TYPE_IS_I(pdu) && ns != vr &&
llc_util_ns_inside_rx_window(ns, vr, llc_sk(sk)->rw) ? 0 : 1;
if (!rc)
dprintk("%s: matched, state=%d, ns=%d, vr=%d\n",
__FUNCTION__, llc_sk(sk)->state, ns, vr);
return rc;
}
/**
* llc_util_nr_inside_tx_window - check if sequence number is in tx window
* @sk: current connection.
* @nr: N(R) of received PDU.
*
* This routine checks if N(R) of received PDU is in range of transmit
* window; on the other hand checks if received PDU acknowledges some
* outstanding PDUs that are in transmit window. Returns 0 for success, 1
* otherwise.
*/
static u16 llc_util_nr_inside_tx_window(struct sock *sk, u8 nr)
{
u8 nr1, nr2;
struct sk_buff *skb;
struct llc_pdu_sn *pdu;
struct llc_opt *llc = llc_sk(sk);
int rc = 0;
if (llc->dev->flags & IFF_LOOPBACK)
goto out;
rc = 1;
if (!skb_queue_len(&llc->pdu_unack_q))
goto out;
skb = skb_peek(&llc->pdu_unack_q);
pdu = llc_pdu_sn_hdr(skb);
nr1 = LLC_I_GET_NS(pdu);
skb = skb_peek_tail(&llc->pdu_unack_q);
pdu = llc_pdu_sn_hdr(skb);
nr2 = LLC_I_GET_NS(pdu);
rc = !llc_circular_between(nr1, nr, (nr2 + 1) % LLC_2_SEQ_NBR_MODULO);
out:
return rc;
}
