C++ DN_SK函数代码示例

static void dn_nsp_send(struct sk_buff *skb)
{
	struct sock *sk = skb->sk;
	struct dn_scp *scp = DN_SK(sk);
	struct dst_entry *dst;
	struct flowi fl;

	skb_reset_transport_header(skb);
	scp->stamp = jiffies;

	dst = sk_dst_check(sk, 0);
	if (dst) {
try_again:
		skb_dst_set(skb, dst);
		dst_output(skb);
		return;
	}

	memset(&fl, 0, sizeof(fl));
	fl.oif = sk->sk_bound_dev_if;
	fl.fld_src = dn_saddr2dn(&scp->addr);
	fl.fld_dst = dn_saddr2dn(&scp->peer);
	dn_sk_ports_copy(&fl, scp);
	fl.proto = DNPROTO_NSP;
	if (dn_route_output_sock(&sk->sk_dst_cache, &fl, sk, 0) == 0) {
		dst = sk_dst_get(sk);
		sk->sk_route_caps = dst->dev->features;
		goto try_again;
	}

	sk->sk_err = EHOSTUNREACH;
	if (!sock_flag(sk, SOCK_DEAD))
		sk->sk_state_change(sk);
}

static void dn_nsp_otherdata(struct sock *sk, struct sk_buff *skb)
{
	struct dn_scp *scp = DN_SK(sk);
	unsigned short segnum;
	struct dn_skb_cb *cb = DN_SKB_CB(skb);
	int queued = 0;

	if (skb->len < 2)
		goto out;

	cb->segnum = segnum = le16_to_cpu(*(__le16 *)skb->data);
	skb_pull(skb, 2);

	if (seq_next(scp->numoth_rcv, segnum)) {

		if (dn_queue_skb(sk, skb, SIGURG, &scp->other_receive_queue) == 0) {
			seq_add(&scp->numoth_rcv, 1);
			scp->other_report = 0;
			queued = 1;
		}
	}

	dn_nsp_send_oth_ack(sk);
out:
	if (!queued)
		kfree_skb(skb);
}

static void dn_nsp_data(struct sock *sk, struct sk_buff *skb)
{
	int queued = 0;
	unsigned short segnum;
	struct dn_skb_cb *cb = DN_SKB_CB(skb);
	struct dn_scp *scp = DN_SK(sk);

	if (skb->len < 2)
		goto out;

	cb->segnum = segnum = le16_to_cpu(*(__le16 *)skb->data);
	skb_pull(skb, 2);

	if (seq_next(scp->numdat_rcv, segnum)) {
		if (dn_queue_skb(sk, skb, SIGIO, &sk->sk_receive_queue) == 0) {
			seq_add(&scp->numdat_rcv, 1);
			queued = 1;
		}

		if ((scp->flowloc_sw == DN_SEND) && dn_congested(sk)) {
			scp->flowloc_sw = DN_DONTSEND;
			dn_nsp_send_link(sk, DN_DONTSEND, 0);
		}
	}

	dn_nsp_send_data_ack(sk);
out:
	if (!queued)
		kfree_skb(skb);
}

void dn_nsp_output(struct sock *sk)
{
	struct dn_scp *scp = DN_SK(sk);
	struct sk_buff *skb;
	unsigned reduce_win = 0;

	/*
	 * First we check for otherdata/linkservice messages
	 */
	if ((skb = skb_peek(&scp->other_xmit_queue)) != NULL)
		reduce_win = dn_nsp_clone_and_send(skb, GFP_ATOMIC);

	/*
	 * If we may not send any data, we don't.
	 * If we are still trying to get some other data down the
	 * channel, we don't try and send any data.
	 */
	if (reduce_win || (scp->flowrem_sw != DN_SEND))
		goto recalc_window;

	if ((skb = skb_peek(&scp->data_xmit_queue)) != NULL)
		reduce_win = dn_nsp_clone_and_send(skb, GFP_ATOMIC);

	/*
	 * If we've sent any frame more than once, we cut the
	 * send window size in half. There is always a minimum
	 * window size of one available.
	 */
recalc_window:
	if (reduce_win) {
		scp->snd_window >>= 1;
		if (scp->snd_window < NSP_MIN_WINDOW)
			scp->snd_window = NSP_MIN_WINDOW;
	}
}

static __le16 *dn_mk_ack_header(struct sock *sk, struct sk_buff *skb, unsigned char msgflag, int hlen, int other)
{
	struct dn_scp *scp = DN_SK(sk);
	unsigned short acknum = scp->numdat_rcv & 0x0FFF;
	unsigned short ackcrs = scp->numoth_rcv & 0x0FFF;
	__le16 *ptr;

	BUG_ON(hlen < 9);

	scp->ackxmt_dat = acknum;
	scp->ackxmt_oth = ackcrs;
	acknum |= 0x8000;
	ackcrs |= 0x8000;

	/* If this is an "other data/ack" message, swap acknum and ackcrs */
	if (other) {
		unsigned short tmp = acknum;
		acknum = ackcrs;
		ackcrs = tmp;
	}

	/* Set "cross subchannel" bit in ackcrs */
	ackcrs |= 0x2000;

	ptr = (__le16 *)dn_mk_common_header(scp, skb, msgflag, hlen);

	*ptr++ = cpu_to_le16(acknum);
	*ptr++ = cpu_to_le16(ackcrs);

	return ptr;
}

void dn_nsp_queue_xmit(struct sock *sk, struct sk_buff *skb,
			gfp_t gfp, int oth)
{
	struct dn_scp *scp = DN_SK(sk);
	struct dn_skb_cb *cb = DN_SKB_CB(skb);
	unsigned long t = ((scp->nsp_srtt >> 2) + scp->nsp_rttvar) >> 1;

	cb->xmit_count = 0;
	dn_nsp_mk_data_header(sk, skb, oth);

	/*
	 * Slow start: If we have been idle for more than
	 * one RTT, then reset window to min size.
	 */
	if ((jiffies - scp->stamp) > t)
		scp->snd_window = NSP_MIN_WINDOW;

	if (oth)
		skb_queue_tail(&scp->other_xmit_queue, skb);
	else
		skb_queue_tail(&scp->data_xmit_queue, skb);

	if (scp->flowrem_sw != DN_SEND)
		return;

	dn_nsp_clone_and_send(skb, gfp);
}

void dn_send_conn_conf(struct sock *sk, gfp_t gfp)
{
	struct dn_scp *scp = DN_SK(sk);
	struct sk_buff *skb = NULL;
	struct nsp_conn_init_msg *msg;
	__u8 len = (__u8)le16_to_cpu(scp->conndata_out.opt_optl);

	if ((skb = dn_alloc_skb(sk, 50 + len, gfp)) == NULL)
		return;

	msg = (struct nsp_conn_init_msg *)skb_put(skb, sizeof(*msg));
	msg->msgflg = 0x28;
	msg->dstaddr = scp->addrrem;
	msg->srcaddr = scp->addrloc;
	msg->services = scp->services_loc;
	msg->info = scp->info_loc;
	msg->segsize = cpu_to_le16(scp->segsize_loc);

	*skb_put(skb,1) = len;

	if (len > 0)
		memcpy(skb_put(skb, len), scp->conndata_out.opt_data, len);


	dn_nsp_send(skb);

	scp->persist = dn_nsp_persist(sk);
	scp->persist_fxn = dn_nsp_retrans_conn_conf;
}

static void dn_slow_timer(unsigned long arg)
{
	struct sock *sk = (struct sock *)arg;
	struct dn_scp *scp = DN_SK(sk);

	bh_lock_sock(sk);

	if (sock_owned_by_user(sk)) {
		sk_reset_timer(sk, &sk->sk_timer, jiffies + HZ / 10);
		goto out;
	}

	if (scp->persist && scp->persist_fxn) {
		if (scp->persist <= SLOW_INTERVAL) {
			scp->persist = 0;

			if (scp->persist_fxn(sk))
				goto out;
		} else {
			scp->persist -= SLOW_INTERVAL;
		}
	}

	if (scp->keepalive && scp->keepalive_fxn && (scp->state == DN_RUN)) {
		if ((jiffies - scp->stamp) >= scp->keepalive)
			scp->keepalive_fxn(sk);
	}

	sk_reset_timer(sk, &sk->sk_timer, jiffies + SLOW_INTERVAL);
out:
	bh_unlock_sock(sk);
	sock_put(sk);
}

/*
 * For this function we've flipped the cross-subchannel bit
 * if the message is an otherdata or linkservice message. Thus
 * we can use it to work out what to update.
 */
static void dn_ack(struct sock *sk, struct sk_buff *skb, unsigned short ack)
{
	struct dn_scp *scp = DN_SK(sk);
	unsigned short type = ((ack >> 12) & 0x0003);
	int wakeup = 0;

	switch (type) {
	case 0: /* ACK - Data */
		if (dn_after(ack, scp->ackrcv_dat)) {
			scp->ackrcv_dat = ack & 0x0fff;
			wakeup |= dn_nsp_check_xmit_queue(sk, skb,
							  &scp->data_xmit_queue,
							  ack);
		}
		break;
	case 1: /* NAK - Data */
		break;
	case 2: /* ACK - OtherData */
		if (dn_after(ack, scp->ackrcv_oth)) {
			scp->ackrcv_oth = ack & 0x0fff;
			wakeup |= dn_nsp_check_xmit_queue(sk, skb,
							  &scp->other_xmit_queue,
							  ack);
		}
		break;
	case 3: /* NAK - OtherData */
		break;
	}

	if (wakeup && !sock_flag(sk, SOCK_DEAD))
		sk->sk_state_change(sk);
}

static void dn_slow_timer(unsigned long arg)
{
	struct sock *sk = (struct sock *)arg;
	struct dn_scp *scp = DN_SK(sk);

	sock_hold(sk);
	bh_lock_sock(sk);

	if (sock_owned_by_user(sk)) {
		sk->sk_timer.expires = jiffies + HZ / 10;
		add_timer(&sk->sk_timer);
		goto out;
	}

	/*
	 * The persist timer is the standard slow timer used for retransmits
	 * in both connection establishment and disconnection as well as
	 * in the RUN state. The different states are catered for by changing
	 * the function pointer in the socket. Setting the timer to a value
	 * of zero turns it off. We allow the persist_fxn to turn the
	 * timer off in a permant way by returning non-zero, so that
	 * timer based routines may remove sockets. This is why we have a
	 * sock_hold()/sock_put() around the timer to prevent the socket
	 * going away in the middle.
	 */
	if (scp->persist && scp->persist_fxn) {
		if (scp->persist <= SLOW_INTERVAL) {
			scp->persist = 0;

			if (scp->persist_fxn(sk))
				goto out;
		} else {
			scp->persist -= SLOW_INTERVAL;
		}
	}

	/*
	 * Check for keepalive timeout. After the other timer 'cos if
	 * the previous timer caused a retransmit, we don't need to
	 * do this. scp->stamp is the last time that we sent a packet.
	 * The keepalive function sends a link service packet to the
	 * other end. If it remains unacknowledged, the standard
	 * socket timers will eventually shut the socket down. Each
	 * time we do this, scp->stamp will be updated, thus
	 * we won't try and send another until scp->keepalive has passed
	 * since the last successful transmission.
	 */
	if (scp->keepalive && scp->keepalive_fxn && (scp->state == DN_RUN)) {
		if ((jiffies - scp->stamp) >= scp->keepalive)
			scp->keepalive_fxn(sk);
	}

	sk->sk_timer.expires = jiffies + SLOW_INTERVAL;

	add_timer(&sk->sk_timer);
out:
	bh_unlock_sock(sk);
	sock_put(sk);
}

static int dn_nsp_retrans_conn_conf(struct sock *sk)
{
	struct dn_scp *scp = DN_SK(sk);

	if (scp->state == DN_CC)
		dn_send_conn_conf(sk, GFP_ATOMIC);

	return 0;
}

static int dn_nsp_retrans_conninit(struct sock *sk)
{
	struct dn_scp *scp = DN_SK(sk);

	if (scp->state == DN_CI)
		dn_nsp_send_conninit(sk, NSP_RCI);

	return 0;
}

void dn_nsp_delayed_ack(struct sock *sk)
{
	struct dn_scp *scp = DN_SK(sk);

	if (scp->ackxmt_oth != scp->numoth_rcv)
		dn_nsp_send_oth_ack(sk);

	if (scp->ackxmt_dat != scp->numdat_rcv)
		dn_nsp_send_data_ack(sk);
}

static void dn_nsp_disc_init(struct sock *sk, struct sk_buff *skb)
{
	struct dn_scp *scp = DN_SK(sk);
	struct dn_skb_cb *cb = DN_SKB_CB(skb);
	unsigned short reason;

	if (skb->len < 2)
		goto out;

	reason = dn_ntohs(*(__u16 *)skb->data);
	skb_pull(skb, 2);

	scp->discdata_in.opt_status = reason;
	scp->discdata_in.opt_optl   = 0;
	memset(scp->discdata_in.opt_data, 0, 16);

	if (skb->len > 0) {
		unsigned char dlen = *skb->data;
		if ((dlen <= 16) && (dlen <= skb->len)) {
			scp->discdata_in.opt_optl = dlen;
			memcpy(scp->discdata_in.opt_data, skb->data + 1, dlen);
		}
	}

	scp->addrrem = cb->src_port;
	sk->state    = TCP_CLOSE;

	switch(scp->state) {
		case DN_CI:
		case DN_CD:
			scp->state = DN_RJ;
			break;
		case DN_RUN:
			sk->shutdown |= SHUTDOWN_MASK;
			scp->state = DN_DN;
			break;
		case DN_DI:
			scp->state = DN_DIC;
			break;
	}

	if (!sk->dead) {
		if (sk->socket->state != SS_UNCONNECTED)
			sk->socket->state = SS_DISCONNECTING;
		sk->state_change(sk);
	}

	dn_nsp_send_disc(sk, NSP_DISCCONF, NSP_REASON_DC, GFP_ATOMIC);
	scp->persist_fxn = dn_destroy_timer;
	scp->persist = dn_nsp_persist(sk);

out:
	kfree_skb(skb);
}

static void dn_nsp_conn_ack(struct sock *sk, struct sk_buff *skb)
{
	struct dn_scp *scp = DN_SK(sk);

	if (scp->state == DN_CI) {
		scp->state = DN_CD;
		scp->persist = 0;
	}

	kfree_skb(skb);
}