llc_station.c

linux 内核源代码

/*
 * llc_station.c - station component of LLC
 *
 * Copyright (c) 1997 by Procom Technology, Inc.
 * 		 2001-2003 by Arnaldo Carvalho de Melo <[e-mail]>
 *
 * 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/init.h>
#include <linux/module.h>
#include <net/llc.h>
#include <net/llc_sap.h>
#include <net/llc_conn.h>
#include <net/llc_c_ac.h>
#include <net/llc_s_ac.h>
#include <net/llc_c_ev.h>
#include <net/llc_c_st.h>
#include <net/llc_s_ev.h>
#include <net/llc_s_st.h>
#include <net/llc_pdu.h>

/**
 * struct llc_station - LLC station component
 *
 * SAP and connection resource manager, one per adapter.
 *
 * @state - state of station
 * @xid_r_count - XID response PDU counter
 * @mac_sa - MAC source address
 * @sap_list - list of related SAPs
 * @ev_q - events entering state mach.
 * @mac_pdu_q - PDUs ready to send to MAC
 */
struct llc_station {
	u8			    state;
	u8			    xid_r_count;
	struct timer_list	    ack_timer;
	u8			    retry_count;
	u8			    maximum_retry;
	struct {
		struct sk_buff_head list;
		spinlock_t	    lock;
	} ev_q;
	struct sk_buff_head	    mac_pdu_q;
};

#define LLC_STATION_ACK_TIME (3 * HZ)

int sysctl_llc_station_ack_timeout = LLC_STATION_ACK_TIME;

/* Types of events (possible values in 'ev->type') */
#define LLC_STATION_EV_TYPE_SIMPLE	1
#define LLC_STATION_EV_TYPE_CONDITION	2
#define LLC_STATION_EV_TYPE_PRIM	3
#define LLC_STATION_EV_TYPE_PDU		4       /* command/response PDU */
#define LLC_STATION_EV_TYPE_ACK_TMR	5
#define LLC_STATION_EV_TYPE_RPT_STATUS	6

/* Events */
#define LLC_STATION_EV_ENABLE_WITH_DUP_ADDR_CHECK		1
#define LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK		2
#define LLC_STATION_EV_ACK_TMR_EXP_LT_RETRY_CNT_MAX_RETRY	3
#define LLC_STATION_EV_ACK_TMR_EXP_EQ_RETRY_CNT_MAX_RETRY	4
#define LLC_STATION_EV_RX_NULL_DSAP_XID_C			5
#define LLC_STATION_EV_RX_NULL_DSAP_0_XID_R_XID_R_CNT_EQ	6
#define LLC_STATION_EV_RX_NULL_DSAP_1_XID_R_XID_R_CNT_EQ	7
#define LLC_STATION_EV_RX_NULL_DSAP_TEST_C			8
#define LLC_STATION_EV_DISABLE_REQ				9

struct llc_station_state_ev {
	u8		 type;
	u8		 prim;
	u8		 prim_type;
	u8		 reason;
	struct list_head node; /* node in station->ev_q.list */
};

static __inline__ struct llc_station_state_ev *
					llc_station_ev(struct sk_buff *skb)
{
	return (struct llc_station_state_ev *)skb->cb;
}

typedef int (*llc_station_ev_t)(struct sk_buff *skb);

#define LLC_STATION_STATE_DOWN		1	/* initial state */
#define LLC_STATION_STATE_DUP_ADDR_CHK	2
#define LLC_STATION_STATE_UP		3

#define LLC_NBR_STATION_STATES		3	/* size of state table */

typedef int (*llc_station_action_t)(struct sk_buff *skb);

/* Station component state table structure */
struct llc_station_state_trans {
	llc_station_ev_t ev;
	u8 next_state;
	llc_station_action_t *ev_actions;
};

struct llc_station_state {
	u8 curr_state;
	struct llc_station_state_trans **transitions;
};

static struct llc_station llc_main_station;

static int llc_stat_ev_enable_with_dup_addr_check(struct sk_buff *skb)
{
	struct llc_station_state_ev *ev = llc_station_ev(skb);

	return ev->type == LLC_STATION_EV_TYPE_SIMPLE &&
	       ev->prim_type ==
			      LLC_STATION_EV_ENABLE_WITH_DUP_ADDR_CHECK ? 0 : 1;
}

static int llc_stat_ev_enable_without_dup_addr_check(struct sk_buff *skb)
{
	struct llc_station_state_ev *ev = llc_station_ev(skb);

	return ev->type == LLC_STATION_EV_TYPE_SIMPLE &&
	       ev->prim_type ==
			LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK ? 0 : 1;
}

static int llc_stat_ev_ack_tmr_exp_lt_retry_cnt_max_retry(struct sk_buff *skb)
{
	struct llc_station_state_ev *ev = llc_station_ev(skb);

	return ev->type == LLC_STATION_EV_TYPE_ACK_TMR &&
		llc_main_station.retry_count <
		llc_main_station.maximum_retry ? 0 : 1;
}

static int llc_stat_ev_ack_tmr_exp_eq_retry_cnt_max_retry(struct sk_buff *skb)
{
	struct llc_station_state_ev *ev = llc_station_ev(skb);

	return ev->type == LLC_STATION_EV_TYPE_ACK_TMR &&
		llc_main_station.retry_count ==
		llc_main_station.maximum_retry ? 0 : 1;
}

static int llc_stat_ev_rx_null_dsap_xid_c(struct sk_buff *skb)
{
	struct llc_station_state_ev *ev = llc_station_ev(skb);
	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

	return ev->type == LLC_STATION_EV_TYPE_PDU &&
	       LLC_PDU_IS_CMD(pdu) &&			/* command PDU */
	       LLC_PDU_TYPE_IS_U(pdu) &&		/* U type PDU */
	       LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_XID &&
	       !pdu->dsap ? 0 : 1;			/* NULL DSAP value */
}

static int llc_stat_ev_rx_null_dsap_0_xid_r_xid_r_cnt_eq(struct sk_buff *skb)
{
	struct llc_station_state_ev *ev = llc_station_ev(skb);
	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

	return ev->type == LLC_STATION_EV_TYPE_PDU &&
	       LLC_PDU_IS_RSP(pdu) &&			/* response PDU */
	       LLC_PDU_TYPE_IS_U(pdu) &&		/* U type PDU */
	       LLC_U_PDU_RSP(pdu) == LLC_1_PDU_CMD_XID &&
	       !pdu->dsap &&				/* NULL DSAP value */
	       !llc_main_station.xid_r_count ? 0 : 1;
}

static int llc_stat_ev_rx_null_dsap_1_xid_r_xid_r_cnt_eq(struct sk_buff *skb)
{
	struct llc_station_state_ev *ev = llc_station_ev(skb);
	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

	return ev->type == LLC_STATION_EV_TYPE_PDU &&
	       LLC_PDU_IS_RSP(pdu) &&			/* response PDU */
	       LLC_PDU_TYPE_IS_U(pdu) &&		/* U type PDU */
	       LLC_U_PDU_RSP(pdu) == LLC_1_PDU_CMD_XID &&
	       !pdu->dsap &&				/* NULL DSAP value */
	       llc_main_station.xid_r_count == 1 ? 0 : 1;
}

static int llc_stat_ev_rx_null_dsap_test_c(struct sk_buff *skb)
{
	struct llc_station_state_ev *ev = llc_station_ev(skb);
	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

	return ev->type == LLC_STATION_EV_TYPE_PDU &&
	       LLC_PDU_IS_CMD(pdu) &&			/* command PDU */
	       LLC_PDU_TYPE_IS_U(pdu) &&		/* U type PDU */
	       LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_TEST &&
	       !pdu->dsap ? 0 : 1;			/* NULL DSAP */
}

static int llc_stat_ev_disable_req(struct sk_buff *skb)
{
	struct llc_station_state_ev *ev = llc_station_ev(skb);

	return ev->type == LLC_STATION_EV_TYPE_PRIM &&
	       ev->prim == LLC_DISABLE_PRIM &&
	       ev->prim_type == LLC_PRIM_TYPE_REQ ? 0 : 1;
}

/**
 *	llc_station_send_pdu - queues PDU to send
 *	@skb: Address of the PDU
 *
 *	Queues a PDU to send to the MAC layer.
 */
static void llc_station_send_pdu(struct sk_buff *skb)
{
	skb_queue_tail(&llc_main_station.mac_pdu_q, skb);
	while ((skb = skb_dequeue(&llc_main_station.mac_pdu_q)) != NULL)
		if (dev_queue_xmit(skb))
			break;
}

static int llc_station_ac_start_ack_timer(struct sk_buff *skb)
{
	mod_timer(&llc_main_station.ack_timer,
		  jiffies + sysctl_llc_station_ack_timeout);
	return 0;
}

static int llc_station_ac_set_retry_cnt_0(struct sk_buff *skb)
{
	llc_main_station.retry_count = 0;
	return 0;
}

static int llc_station_ac_inc_retry_cnt_by_1(struct sk_buff *skb)
{
	llc_main_station.retry_count++;
	return 0;
}

static int llc_station_ac_set_xid_r_cnt_0(struct sk_buff *skb)
{
	llc_main_station.xid_r_count = 0;
	return 0;
}

static int llc_station_ac_inc_xid_r_cnt_by_1(struct sk_buff *skb)
{
	llc_main_station.xid_r_count++;
	return 0;
}

static int llc_station_ac_send_null_dsap_xid_c(struct sk_buff *skb)
{
	int rc = 1;
	struct sk_buff *nskb = llc_alloc_frame(NULL, skb->dev);

	if (!nskb)
		goto out;
	llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, 0, LLC_PDU_CMD);
	llc_pdu_init_as_xid_cmd(nskb, LLC_XID_NULL_CLASS_2, 127);
	rc = llc_mac_hdr_init(nskb, llc_station_mac_sa, llc_station_mac_sa);
	if (unlikely(rc))
		goto free;
	llc_station_send_pdu(nskb);
out:
	return rc;
free:
	kfree_skb(skb);
	goto out;
}

static int llc_station_ac_send_xid_r(struct sk_buff *skb)
{
	u8 mac_da[ETH_ALEN], dsap;
	int rc = 1;
	struct sk_buff* nskb = llc_alloc_frame(NULL, skb->dev);

	if (!nskb)
		goto out;
	rc = 0;
	llc_pdu_decode_sa(skb, mac_da);
	llc_pdu_decode_ssap(skb, &dsap);
	llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
	llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);
	rc = llc_mac_hdr_init(nskb, llc_station_mac_sa, mac_da);
	if (unlikely(rc))
		goto free;
	llc_station_send_pdu(nskb);
out:
	return rc;
free:
	kfree_skb(skb);
	goto out;
}

static int llc_station_ac_send_test_r(struct sk_buff *skb)
{
	u8 mac_da[ETH_ALEN], dsap;
	int rc = 1;
	struct sk_buff *nskb = llc_alloc_frame(NULL, skb->dev);

	if (!nskb)
		goto out;
	rc = 0;
	llc_pdu_decode_sa(skb, mac_da);
	llc_pdu_decode_ssap(skb, &dsap);
	llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
	llc_pdu_init_as_test_rsp(nskb, skb);
	rc = llc_mac_hdr_init(nskb, llc_station_mac_sa, mac_da);
	if (unlikely(rc))
		goto free;
	llc_station_send_pdu(nskb);
out:
	return rc;
free:
	kfree_skb(skb);
	goto out;
}

static int llc_station_ac_report_status(struct sk_buff *skb)
{
	return 0;
}

/* COMMON STATION STATE transitions */

/* dummy last-transition indicator; common to all state transition groups
 * last entry for this state
 * all members are zeros, .bss zeroes it
 */
static struct llc_station_state_trans llc_stat_state_trans_end;

/* DOWN STATE transitions */

/* state transition for LLC_STATION_EV_ENABLE_WITH_DUP_ADDR_CHECK event */
static llc_station_action_t llc_stat_down_state_actions_1[] = {
	[0] = llc_station_ac_start_ack_timer,
	[1] = llc_station_ac_set_retry_cnt_0,
	[2] = llc_station_ac_set_xid_r_cnt_0,
	[3] = llc_station_ac_send_null_dsap_xid_c,
	[4] = NULL,
};

static struct llc_station_state_trans llc_stat_down_state_trans_1 = {
	.ev	    = llc_stat_ev_enable_with_dup_addr_check,
	.next_state = LLC_STATION_STATE_DUP_ADDR_CHK,
	.ev_actions = llc_stat_down_state_actions_1,
};

/* state transition for LLC_STATION_EV_ENABLE_WITHOUT_DUP_ADDR_CHECK event */
static llc_station_action_t llc_stat_down_state_actions_2[] = {
	[0] = llc_station_ac_report_status,	/* STATION UP */
	[1] = NULL,
};

static struct llc_station_state_trans llc_stat_down_state_trans_2 = {
	.ev	    = llc_stat_ev_enable_without_dup_addr_check,