llc_conn.c

linux 内核源代码

 *	@sap: SAP
 *	@daddr: address of remote LLC (MAC + SAP)
 *	@laddr: address of local LLC (MAC + SAP)
 *
 *	Search connection list of the SAP and finds connection using the remote
 *	mac, remote sap, local mac, and local sap. Returns pointer for
 *	connection found, %NULL otherwise.
 *	Caller has to make sure local_bh is disabled.
 */
static struct sock *__llc_lookup_established(struct llc_sap *sap,
					     struct llc_addr *daddr,
					     struct llc_addr *laddr)
{
	struct sock *rc;
	struct hlist_node *node;

	read_lock(&sap->sk_list.lock);
	sk_for_each(rc, node, &sap->sk_list.list) {
		struct llc_sock *llc = llc_sk(rc);

		if (llc->laddr.lsap == laddr->lsap &&
		    llc->daddr.lsap == daddr->lsap &&
		    llc_mac_match(llc->laddr.mac, laddr->mac) &&
		    llc_mac_match(llc->daddr.mac, daddr->mac)) {
			sock_hold(rc);
			goto found;
		}
	}
	rc = NULL;
found:
	read_unlock(&sap->sk_list.lock);
	return rc;
}

struct sock *llc_lookup_established(struct llc_sap *sap,
				    struct llc_addr *daddr,
				    struct llc_addr *laddr)
{
	struct sock *sk;

	local_bh_disable();
	sk = __llc_lookup_established(sap, daddr, laddr);
	local_bh_enable();
	return sk;
}

/**
 *	llc_lookup_listener - Finds listener for local MAC + SAP
 *	@sap: SAP
 *	@laddr: address of local LLC (MAC + SAP)
 *
 *	Search connection list of the SAP and finds connection listening on
 *	local mac, and local sap. Returns pointer for parent socket found,
 *	%NULL otherwise.
 *	Caller has to make sure local_bh is disabled.
 */
static struct sock *llc_lookup_listener(struct llc_sap *sap,
					struct llc_addr *laddr)
{
	struct sock *rc;
	struct hlist_node *node;

	read_lock(&sap->sk_list.lock);
	sk_for_each(rc, node, &sap->sk_list.list) {
		struct llc_sock *llc = llc_sk(rc);

		if (rc->sk_type == SOCK_STREAM && rc->sk_state == TCP_LISTEN &&
		    llc->laddr.lsap == laddr->lsap &&
		    (llc_mac_match(llc->laddr.mac, laddr->mac) ||
		     llc_mac_null(llc->laddr.mac))) {
			sock_hold(rc);
			goto found;
		}
	}
	rc = NULL;
found:
	read_unlock(&sap->sk_list.lock);
	return rc;
}

static struct sock *__llc_lookup(struct llc_sap *sap,
				 struct llc_addr *daddr,
				 struct llc_addr *laddr)
{
	struct sock *sk = __llc_lookup_established(sap, daddr, laddr);

	return sk ? : llc_lookup_listener(sap, laddr);
}

/**
 *	llc_data_accept_state - designates if in this state data can be sent.
 *	@state: state of connection.
 *
 *	Returns 0 if data can be sent, 1 otherwise.
 */
u8 llc_data_accept_state(u8 state)
{
	return state != LLC_CONN_STATE_NORMAL && state != LLC_CONN_STATE_BUSY &&
	       state != LLC_CONN_STATE_REJ;
}

/**
 *	llc_find_next_offset - finds offset for next category of transitions
 *	@state: state table.
 *	@offset: start offset.
 *
 *	Finds offset of next category of transitions in transition table.
 *	Returns the start index of next category.
 */
static u16 __init llc_find_next_offset(struct llc_conn_state *state, u16 offset)
{
	u16 cnt = 0;
	struct llc_conn_state_trans **next_trans;

	for (next_trans = state->transitions + offset;
	     (*next_trans)->ev; next_trans++)
		++cnt;
	return cnt;
}

/**
 *	llc_build_offset_table - builds offset table of connection
 *
 *	Fills offset table of connection state transition table
 *	(llc_offset_table).
 */
void __init llc_build_offset_table(void)
{
	struct llc_conn_state *curr_state;
	int state, ev_type, next_offset;

	for (state = 0; state < NBR_CONN_STATES; state++) {
		curr_state = &llc_conn_state_table[state];
		next_offset = 0;
		for (ev_type = 0; ev_type < NBR_CONN_EV; ev_type++) {
			llc_offset_table[state][ev_type] = next_offset;
			next_offset += llc_find_next_offset(curr_state,
							    next_offset) + 1;
		}
	}
}

/**
 *	llc_find_offset - finds start offset of category of transitions
 *	@state: state of connection
 *	@ev_type: type of happened event
 *
 *	Finds start offset of desired category of transitions. Returns the
 *	desired start offset.
 */
static int llc_find_offset(int state, int ev_type)
{
	int rc = 0;
	/* at this stage, llc_offset_table[..][2] is not important. it is for
	 * init_pf_cycle and I don't know what is it.
	 */
	switch (ev_type) {
	case LLC_CONN_EV_TYPE_PRIM:
		rc = llc_offset_table[state][0]; break;
	case LLC_CONN_EV_TYPE_PDU:
		rc = llc_offset_table[state][4]; break;
	case LLC_CONN_EV_TYPE_SIMPLE:
		rc = llc_offset_table[state][1]; break;
	case LLC_CONN_EV_TYPE_P_TMR:
	case LLC_CONN_EV_TYPE_ACK_TMR:
	case LLC_CONN_EV_TYPE_REJ_TMR:
	case LLC_CONN_EV_TYPE_BUSY_TMR:
		rc = llc_offset_table[state][3]; break;
	}
	return rc;
}

/**
 *	llc_sap_add_socket - adds a socket to a SAP
 *	@sap: SAP
 *	@sk: socket
 *
 *	This function adds a socket to sk_list of a SAP.
 */
void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk)
{
	llc_sap_hold(sap);
	write_lock_bh(&sap->sk_list.lock);
	llc_sk(sk)->sap = sap;
	sk_add_node(sk, &sap->sk_list.list);
	write_unlock_bh(&sap->sk_list.lock);
}

/**
 *	llc_sap_remove_socket - removes a socket from SAP
 *	@sap: SAP
 *	@sk: socket
 *
 *	This function removes a connection from sk_list.list of a SAP if
 *	the connection was in this list.
 */
void llc_sap_remove_socket(struct llc_sap *sap, struct sock *sk)
{
	write_lock_bh(&sap->sk_list.lock);
	sk_del_node_init(sk);
	write_unlock_bh(&sap->sk_list.lock);
	llc_sap_put(sap);
}

/**
 *	llc_conn_rcv - sends received pdus to the connection state machine
 *	@sk: current connection structure.
 *	@skb: received frame.
 *
 *	Sends received pdus to the connection state machine.
 */
static int llc_conn_rcv(struct sock* sk, struct sk_buff *skb)
{
	struct llc_conn_state_ev *ev = llc_conn_ev(skb);

	ev->type   = LLC_CONN_EV_TYPE_PDU;
	ev->reason = 0;
	return llc_conn_state_process(sk, skb);
}

static struct sock *llc_create_incoming_sock(struct sock *sk,
					     struct net_device *dev,
					     struct llc_addr *saddr,
					     struct llc_addr *daddr)
{
	struct sock *newsk = llc_sk_alloc(sk->sk_net, sk->sk_family, GFP_ATOMIC,
					  sk->sk_prot);
	struct llc_sock *newllc, *llc = llc_sk(sk);

	if (!newsk)
		goto out;
	newllc = llc_sk(newsk);
	memcpy(&newllc->laddr, daddr, sizeof(newllc->laddr));
	memcpy(&newllc->daddr, saddr, sizeof(newllc->daddr));
	newllc->dev = dev;
	dev_hold(dev);
	llc_sap_add_socket(llc->sap, newsk);
	llc_sap_hold(llc->sap);
out:
	return newsk;
}

void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
{
	struct llc_addr saddr, daddr;
	struct sock *sk;

	llc_pdu_decode_sa(skb, saddr.mac);
	llc_pdu_decode_ssap(skb, &saddr.lsap);
	llc_pdu_decode_da(skb, daddr.mac);
	llc_pdu_decode_dsap(skb, &daddr.lsap);

	sk = __llc_lookup(sap, &saddr, &daddr);
	if (!sk)
		goto drop;

	bh_lock_sock(sk);
	/*
	 * This has to be done here and not at the upper layer ->accept
	 * method because of the way the PROCOM state machine works:
	 * it needs to set several state variables (see, for instance,
	 * llc_adm_actions_2 in net/llc/llc_c_st.c) and send a packet to
	 * the originator of the new connection, and this state has to be
	 * in the newly created struct sock private area. -acme
	 */
	if (unlikely(sk->sk_state == TCP_LISTEN)) {
		struct sock *newsk = llc_create_incoming_sock(sk, skb->dev,
							      &saddr, &daddr);
		if (!newsk)
			goto drop_unlock;
		skb_set_owner_r(skb, newsk);
	} else {
		/*
		 * Can't be skb_set_owner_r, this will be done at the
		 * llc_conn_state_process function, later on, when we will use
		 * skb_queue_rcv_skb to send it to upper layers, this is
		 * another trick required to cope with how the PROCOM state
		 * machine works. -acme
		 */
		skb->sk = sk;
	}
	if (!sock_owned_by_user(sk))
		llc_conn_rcv(sk, skb);
	else {
		dprintk("%s: adding to backlog...\n", __FUNCTION__);
		llc_set_backlog_type(skb, LLC_PACKET);
		sk_add_backlog(sk, skb);
	}
out:
	bh_unlock_sock(sk);
	sock_put(sk);
	return;
drop:
	kfree_skb(skb);
	return;
drop_unlock:
	kfree_skb(skb);
	goto out;
}

#undef LLC_REFCNT_DEBUG
#ifdef LLC_REFCNT_DEBUG
static atomic_t llc_sock_nr;
#endif

/**
 *	llc_backlog_rcv - Processes rx frames and expired timers.
 *	@sk: LLC sock (p8022 connection)
 *	@skb: queued rx frame or event
 *
 *	This function processes frames that has received and timers that has
 *	expired during sending an I pdu (refer to data_req_handler).  frames
 *	queue by llc_rcv function (llc_mac.c) and timers queue by timer
 *	callback functions(llc_c_ac.c).
 */
static int llc_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
	int rc = 0;
	struct llc_sock *llc = llc_sk(sk);

	if (likely(llc_backlog_type(skb) == LLC_PACKET)) {
		if (likely(llc->state > 1)) /* not closed */
			rc = llc_conn_rcv(sk, skb);
		else
			goto out_kfree_skb;
	} else if (llc_backlog_type(skb) == LLC_EVENT) {
		/* timer expiration event */
		if (likely(llc->state > 1))  /* not closed */
			rc = llc_conn_state_process(sk, skb);
		else
			goto out_kfree_skb;
	} else {
		printk(KERN_ERR "%s: invalid skb in backlog\n", __FUNCTION__);
		goto out_kfree_skb;
	}
out:
	return rc;
out_kfree_skb:
	kfree_skb(skb);
	goto out;
}

/**
 *     llc_sk_init - Initializes a socket with default llc values.
 *     @sk: socket to initialize.
 *
 *     Initializes a socket with default llc values.
 */
static void llc_sk_init(struct sock* sk)
{
	struct llc_sock *llc = llc_sk(sk);

	llc->state    = LLC_CONN_STATE_ADM;
	llc->inc_cntr = llc->dec_cntr = 2;
	llc->dec_step = llc->connect_step = 1;

	init_timer(&llc->ack_timer.timer);
	llc->ack_timer.expire	      = sysctl_llc2_ack_timeout;
	llc->ack_timer.timer.data     = (unsigned long)sk;
	llc->ack_timer.timer.function = llc_conn_ack_tmr_cb;

	init_timer(&llc->pf_cycle_timer.timer);
	llc->pf_cycle_timer.expire	   = sysctl_llc2_p_timeout;
	llc->pf_cycle_timer.timer.data     = (unsigned long)sk;
	llc->pf_cycle_timer.timer.function = llc_conn_pf_cycle_tmr_cb;

	init_timer(&llc->rej_sent_timer.timer);
	llc->rej_sent_timer.expire	   = sysctl_llc2_rej_timeout;
	llc->rej_sent_timer.timer.data     = (unsigned long)sk;
	llc->rej_sent_timer.timer.function = llc_conn_rej_tmr_cb;

	init_timer(&llc->busy_state_timer.timer);
	llc->busy_state_timer.expire	     = sysctl_llc2_busy_timeout;
	llc->busy_state_timer.timer.data     = (unsigned long)sk;
	llc->busy_state_timer.timer.function = llc_conn_busy_tmr_cb;

	llc->n2 = 2;   /* max retransmit */
	llc->k  = 2;   /* tx win size, will adjust dynam */
	llc->rw = 128; /* rx win size (opt and equal to
			* tx_win of remote LLC) */
	skb_queue_head_init(&llc->pdu_unack_q);
	sk->sk_backlog_rcv = llc_backlog_rcv;
}

/**
 *	llc_sk_alloc - Allocates LLC sock
 *	@family: upper layer protocol family
 *	@priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 *
 *	Allocates a LLC sock and initializes it. Returns the new LLC sock
 *	or %NULL if there's no memory available for one
 */
struct sock *llc_sk_alloc(struct net *net, int family, gfp_t priority, struct proto *prot)
{
	struct sock *sk = sk_alloc(net, family, priority, prot);

	if (!sk)
		goto out;
	llc_sk_init(sk);
	sock_init_data(NULL, sk);
#ifdef LLC_REFCNT_DEBUG
	atomic_inc(&llc_sock_nr);
	printk(KERN_DEBUG "LLC socket %p created in %s, now we have %d alive\n", sk,
		__FUNCTION__, atomic_read(&llc_sock_nr));
#endif
out:
	return sk;
}

/**
 *	llc_sk_free - Frees a LLC socket
 *	@sk - socket to free
 *
 *	Frees a LLC socket
 */
void llc_sk_free(struct sock *sk)
{
	struct llc_sock *llc = llc_sk(sk);

	llc->state = LLC_CONN_OUT_OF_SVC;
	/* Stop all (possibly) running timers */
	llc_conn_ac_stop_all_timers(sk, NULL);
#ifdef DEBUG_LLC_CONN_ALLOC
	printk(KERN_INFO "%s: unackq=%d, txq=%d\n", __FUNCTION__,
		skb_queue_len(&llc->pdu_unack_q),
		skb_queue_len(&sk->sk_write_queue));
#endif
	skb_queue_purge(&sk->sk_receive_queue);
	skb_queue_purge(&sk->sk_write_queue);
	skb_queue_purge(&llc->pdu_unack_q);
#ifdef LLC_REFCNT_DEBUG
	if (atomic_read(&sk->sk_refcnt) != 1) {
		printk(KERN_DEBUG "Destruction of LLC sock %p delayed in %s, cnt=%d\n",
			sk, __FUNCTION__, atomic_read(&sk->sk_refcnt));
		printk(KERN_DEBUG "%d LLC sockets are still alive\n",
			atomic_read(&llc_sock_nr));
	} else {
		atomic_dec(&llc_sock_nr);
		printk(KERN_DEBUG "LLC socket %p released in %s, %d are still alive\n", sk,
			__FUNCTION__, atomic_read(&llc_sock_nr));
	}
#endif
	sock_put(sk);
}

/**
 *	llc_sk_reset - resets a connection
 *	@sk: LLC socket to reset
 *
 *	Resets a connection to the out of service state. Stops its timers
 *	and frees any frames in the queues of the connection.
 */
void llc_sk_reset(struct sock *sk)
{
	struct llc_sock *llc = llc_sk(sk);

	llc_conn_ac_stop_all_timers(sk, NULL);
	skb_queue_purge(&sk->sk_write_queue);
	skb_queue_purge(&llc->pdu_unack_q);
	llc->remote_busy_flag	= 0;
	llc->cause_flag		= 0;
	llc->retry_count	= 0;
	llc_conn_set_p_flag(sk, 0);
	llc->f_flag		= 0;
	llc->s_flag		= 0;
	llc->ack_pf		= 0;
	llc->first_pdu_Ns	= 0;
	llc->ack_must_be_send	= 0;
	llc->dec_step		= 1;
	llc->inc_cntr		= 2;
	llc->dec_cntr		= 2;
	llc->X			= 0;
	llc->failed_data_req	= 0 ;
	llc->last_nr		= 0;
}