/* * llc_c_ac.c - actions performed during connection state transition. * * Description: * Functions in this module are implementation of connection component actions * Details of actions can be found in IEEE-802.2 standard document. * All functions have one connection and one event as input argument. All of * them return 0 On success and 1 otherwise. * * Copyright (c) 1997 by Procom Technology, Inc. * 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br> * * This program can be redistributed or modified under the terms of the * GNU General Public License as published by the Free Software Foundation. * This program is distributed without any warranty or implied warranty * of merchantability or fitness for a particular purpose. * * See the GNU General Public License for more details.
*/ #include <linux/netdevice.h> #include <linux/slab.h> #include <net/llc_conn.h> #include <net/llc_sap.h> #include <net/sock.h> #include <net/llc_c_ev.h> #include <net/llc_c_ac.h> #include <net/llc_c_st.h> #include <net/llc_pdu.h> #include <net/llc.h>
/** * llc_conn_ac_send_ack_if_needed - check if ack is needed * @sk: current connection structure * @skb: current event * * Checks number of received PDUs which have not been acknowledged, yet, * If number of them reaches to "npta"(Number of PDUs To Acknowledge) then * sends an RR response as acknowledgement for them. Returns 0 for * success, 1 otherwise.
*/ int llc_conn_ac_send_ack_if_needed(struct sock *sk, struct sk_buff *skb)
{
u8 pf_bit; struct llc_sock *llc = llc_sk(sk);
/** * llc_conn_ac_rst_sendack_flag - resets ack_must_be_send flag * @sk: current connection structure * @skb: current event * * This action resets ack_must_be_send flag of given connection, this flag * indicates if there is any PDU which has not been acknowledged yet. * Returns 0 for success, 1 otherwise.
*/ int llc_conn_ac_rst_sendack_flag(struct sock *sk, struct sk_buff *skb)
{
llc_sk(sk)->ack_must_be_send = llc_sk(sk)->ack_pf = 0; return 0;
}
/** * llc_conn_ac_send_i_rsp_f_set_ackpf - acknowledge received PDUs * @sk: current connection structure * @skb: current event * * Sends an I response PDU with f-bit set to ack_pf flag as acknowledge to * all received PDUs which have not been acknowledged, yet. ack_pf flag is * set to one if one PDU with p-bit set to one is received. Returns 0 for * success, 1 otherwise.
*/ staticint llc_conn_ac_send_i_rsp_f_set_ackpf(struct sock *sk, struct sk_buff *skb)
{ int rc; struct llc_sock *llc = llc_sk(sk); struct llc_sap *sap = llc->sap;
/** * llc_conn_ac_send_i_as_ack - sends an I-format PDU to acknowledge rx PDUs * @sk: current connection structure. * @skb: current event. * * This action sends an I-format PDU as acknowledge to received PDUs which * have not been acknowledged, yet, if there is any. By using of this * action number of acknowledgements decreases, this technic is called * piggy backing. Returns 0 for success, 1 otherwise.
*/ int llc_conn_ac_send_i_as_ack(struct sock *sk, struct sk_buff *skb)
{ struct llc_sock *llc = llc_sk(sk); int ret;
if (llc->ack_must_be_send) {
ret = llc_conn_ac_send_i_rsp_f_set_ackpf(sk, skb);
llc->ack_must_be_send = 0 ;
llc->ack_pf = 0;
} else {
ret = llc_conn_ac_send_i_cmd_p_set_0(sk, skb);
}
return ret;
}
/** * llc_conn_ac_send_rr_rsp_f_set_ackpf - ack all rx PDUs not yet acked * @sk: current connection structure. * @skb: current event. * * This action sends an RR response with f-bit set to ack_pf flag as * acknowledge to all received PDUs which have not been acknowledged, yet, * if there is any. ack_pf flag indicates if a PDU has been received with * p-bit set to one. Returns 0 for success, 1 otherwise.
*/ staticint llc_conn_ac_send_rr_rsp_f_set_ackpf(struct sock *sk, struct sk_buff *skb)
{ int rc = -ENOBUFS; struct llc_sock *llc = llc_sk(sk); struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);
/** * 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.
*/ staticint llc_conn_ac_inc_npta_value(struct sock *sk, struct sk_buff *skb)
{ struct llc_sock *llc = llc_sk(sk);
/** * 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);
/** * 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->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;
timer_delete(&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);
} elseif (llc->failed_data_req) {
u8 f_bit;
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.
*/ staticvoid 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",
__func__);
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);
}
}
}
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