ccid3.c

LINUX 2.6.17.4的源码

			switch (step) {
			case 0:
				tstamp	  = entry->dccphrx_tstamp;
				win_count = entry->dccphrx_ccval;
				step = 1;
				break;
			case 1:
				interval = win_count - entry->dccphrx_ccval;
				if (interval < 0)
					interval += TFRC_WIN_COUNT_LIMIT;
				if (interval > 4)
					goto found;
				break;
			}
		}
	}

	if (unlikely(step == 0)) {
		LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, packet history "
			       "contains no data packets!\n",
			       __FUNCTION__, dccp_role(sk), sk);
		return ~0;
	}

	if (unlikely(interval == 0)) {
		LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, Could not find a "
			       "win_count interval > 0. Defaulting to 1\n",
			       __FUNCTION__, dccp_role(sk), sk);
		interval = 1;
	}
found:
	rtt = timeval_delta(&tstamp, &tail->dccphrx_tstamp) * 4 / interval;
	ccid3_pr_debug("%s, sk=%p, approximated RTT to %uus\n",
		       dccp_role(sk), sk, rtt);
	if (rtt == 0)
		rtt = 1;

	dccp_timestamp(sk, &tstamp);
	delta = timeval_delta(&tstamp, &hcrx->ccid3hcrx_tstamp_last_feedback);
	x_recv = usecs_div(hcrx->ccid3hcrx_bytes_recv, delta);

	tmp1 = (u64)x_recv * (u64)rtt;
	do_div(tmp1,10000000);
	tmp2 = (u32)tmp1;
	fval = (hcrx->ccid3hcrx_s * 100000) / tmp2;
	/* do not alter order above or you will get overflow on 32 bit */
	p = tfrc_calc_x_reverse_lookup(fval);
	ccid3_pr_debug("%s, sk=%p, receive rate=%u bytes/s, implied "
		       "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);

	if (p == 0)
		return ~0;
	else
		return 1000000 / p; 
}

static void ccid3_hc_rx_update_li(struct sock *sk, u64 seq_loss, u8 win_loss)
{
	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);

	if (seq_loss != DCCP_MAX_SEQNO + 1 &&
	    list_empty(&hcrx->ccid3hcrx_li_hist)) {
		struct dccp_li_hist_entry *li_tail;

		li_tail = dccp_li_hist_interval_new(ccid3_li_hist,
						    &hcrx->ccid3hcrx_li_hist,
						    seq_loss, win_loss);
		if (li_tail == NULL)
			return;
		li_tail->dccplih_interval = ccid3_hc_rx_calc_first_li(sk);
	} else
		    LIMIT_NETDEBUG(KERN_WARNING "%s: FIXME: find end of "
				   "interval\n", __FUNCTION__);
}

static void ccid3_hc_rx_detect_loss(struct sock *sk)
{
	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
	u8 win_loss;
	const u64 seq_loss = dccp_rx_hist_detect_loss(&hcrx->ccid3hcrx_hist,
						      &hcrx->ccid3hcrx_li_hist,
						      &win_loss);

	ccid3_hc_rx_update_li(sk, seq_loss, win_loss);
}

static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
	const struct dccp_options_received *opt_recv;
	struct dccp_rx_hist_entry *packet;
	struct timeval now;
	u8 win_count;
	u32 p_prev, r_sample, t_elapsed;
	int ins;

	BUG_ON(hcrx == NULL ||
	       !(hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA ||
		 hcrx->ccid3hcrx_state == TFRC_RSTATE_DATA));

	opt_recv = &dccp_sk(sk)->dccps_options_received;

	switch (DCCP_SKB_CB(skb)->dccpd_type) {
	case DCCP_PKT_ACK:
		if (hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)
			return;
	case DCCP_PKT_DATAACK:
		if (opt_recv->dccpor_timestamp_echo == 0)
			break;
		p_prev = hcrx->ccid3hcrx_rtt;
		dccp_timestamp(sk, &now);
		timeval_sub_usecs(&now, opt_recv->dccpor_timestamp_echo * 10);
		r_sample = timeval_usecs(&now);
		t_elapsed = opt_recv->dccpor_elapsed_time * 10;

		if (unlikely(r_sample <= t_elapsed))
			LIMIT_NETDEBUG(KERN_WARNING "%s: r_sample=%uus, "
				       "t_elapsed=%uus\n",
				       __FUNCTION__, r_sample, t_elapsed);
		else
			r_sample -= t_elapsed;

		if (hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)
			hcrx->ccid3hcrx_rtt = r_sample;
		else
			hcrx->ccid3hcrx_rtt = (hcrx->ccid3hcrx_rtt * 9) / 10 +
					      r_sample / 10;

		if (p_prev != hcrx->ccid3hcrx_rtt)
			ccid3_pr_debug("%s, New RTT=%luus, elapsed time=%u\n",
				       dccp_role(sk), hcrx->ccid3hcrx_rtt,
				       opt_recv->dccpor_elapsed_time);
		break;
	case DCCP_PKT_DATA:
		break;
	default: /* We're not interested in other packet types, move along */
		return;
	}

	packet = dccp_rx_hist_entry_new(ccid3_rx_hist, sk, opt_recv->dccpor_ndp,
					skb, SLAB_ATOMIC);
	if (unlikely(packet == NULL)) {
		LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, Not enough mem to "
				"add rx packet to history, consider it lost!\n",
			       __FUNCTION__, dccp_role(sk), sk);
		return;
	}

	win_count = packet->dccphrx_ccval;

	ins = dccp_rx_hist_add_packet(ccid3_rx_hist, &hcrx->ccid3hcrx_hist,
				      &hcrx->ccid3hcrx_li_hist, packet);

	if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK)
		return;

	switch (hcrx->ccid3hcrx_state) {
	case TFRC_RSTATE_NO_DATA:
		ccid3_pr_debug("%s, sk=%p(%s), skb=%p, sending initial "
			       "feedback\n",
			       dccp_role(sk), sk,
			       dccp_state_name(sk->sk_state), skb);
		ccid3_hc_rx_send_feedback(sk);
		ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
		return;
	case TFRC_RSTATE_DATA:
		hcrx->ccid3hcrx_bytes_recv += skb->len -
					      dccp_hdr(skb)->dccph_doff * 4;
		if (ins != 0)
			break;

		dccp_timestamp(sk, &now);
		if (timeval_delta(&now, &hcrx->ccid3hcrx_tstamp_last_ack) >=
		    hcrx->ccid3hcrx_rtt) {
			hcrx->ccid3hcrx_tstamp_last_ack = now;
			ccid3_hc_rx_send_feedback(sk);
		}
		return;
	default:
		printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
		       __FUNCTION__, dccp_role(sk), sk, hcrx->ccid3hcrx_state);
		dump_stack();
		return;
	}

	/* Dealing with packet loss */
	ccid3_pr_debug("%s, sk=%p(%s), data loss! Reacting...\n",
		       dccp_role(sk), sk, dccp_state_name(sk->sk_state));

	ccid3_hc_rx_detect_loss(sk);
	p_prev = hcrx->ccid3hcrx_p;
	
	/* Calculate loss event rate */
	if (!list_empty(&hcrx->ccid3hcrx_li_hist)) {
		u32 i_mean = dccp_li_hist_calc_i_mean(&hcrx->ccid3hcrx_li_hist);

		/* Scaling up by 1000000 as fixed decimal */
		if (i_mean != 0)
			hcrx->ccid3hcrx_p = 1000000 / i_mean;
	}

	if (hcrx->ccid3hcrx_p > p_prev) {
		ccid3_hc_rx_send_feedback(sk);
		return;
	}
}

static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
{
	struct dccp_sock *dp = dccp_sk(sk);
	struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);

	ccid3_pr_debug("%s, sk=%p\n", dccp_role(sk), sk);

	if (dp->dccps_packet_size >= TFRC_MIN_PACKET_SIZE &&
	    dp->dccps_packet_size <= TFRC_MAX_PACKET_SIZE)
		hcrx->ccid3hcrx_s = dp->dccps_packet_size;
	else
		hcrx->ccid3hcrx_s = TFRC_STD_PACKET_SIZE;

	hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
	INIT_LIST_HEAD(&hcrx->ccid3hcrx_hist);
	INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
	dccp_timestamp(sk, &hcrx->ccid3hcrx_tstamp_last_ack);
	hcrx->ccid3hcrx_tstamp_last_feedback = hcrx->ccid3hcrx_tstamp_last_ack;
	hcrx->ccid3hcrx_rtt = 5000; /* XXX 5ms for now... */
	return 0;
}

static void ccid3_hc_rx_exit(struct sock *sk)
{
	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);

	BUG_ON(hcrx == NULL);

	ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM);

	/* Empty packet history */
	dccp_rx_hist_purge(ccid3_rx_hist, &hcrx->ccid3hcrx_hist);

	/* Empty loss interval history */
	dccp_li_hist_purge(ccid3_li_hist, &hcrx->ccid3hcrx_li_hist);
}

static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
{
	const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);

	/* Listen socks doesn't have a private CCID block */
	if (sk->sk_state == DCCP_LISTEN)
		return;

	BUG_ON(hcrx == NULL);

	info->tcpi_ca_state	= hcrx->ccid3hcrx_state;
	info->tcpi_options	|= TCPI_OPT_TIMESTAMPS;
	info->tcpi_rcv_rtt	= hcrx->ccid3hcrx_rtt;
}

static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
{
	const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);

	/* Listen socks doesn't have a private CCID block */
	if (sk->sk_state == DCCP_LISTEN)
		return;

	BUG_ON(hctx == NULL);

	info->tcpi_rto = hctx->ccid3hctx_t_rto;
	info->tcpi_rtt = hctx->ccid3hctx_rtt;
}

static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
				  u32 __user *optval, int __user *optlen)
{
	const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
	const void *val;
	
	/* Listen socks doesn't have a private CCID block */
	if (sk->sk_state == DCCP_LISTEN)
		return -EINVAL;

	switch (optname) {
	case DCCP_SOCKOPT_CCID_RX_INFO:
		if (len < sizeof(hcrx->ccid3hcrx_tfrc))
			return -EINVAL;
		len = sizeof(hcrx->ccid3hcrx_tfrc);
		val = &hcrx->ccid3hcrx_tfrc;
		break;
	default:
		return -ENOPROTOOPT;
	}

	if (put_user(len, optlen) || copy_to_user(optval, val, len))
		return -EFAULT;

	return 0;
}

static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len,
				  u32 __user *optval, int __user *optlen)
{
	const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
	const void *val;
	
	/* Listen socks doesn't have a private CCID block */
	if (sk->sk_state == DCCP_LISTEN)
		return -EINVAL;

	switch (optname) {
	case DCCP_SOCKOPT_CCID_TX_INFO:
		if (len < sizeof(hctx->ccid3hctx_tfrc))
			return -EINVAL;
		len = sizeof(hctx->ccid3hctx_tfrc);
		val = &hctx->ccid3hctx_tfrc;
		break;
	default:
		return -ENOPROTOOPT;
	}

	if (put_user(len, optlen) || copy_to_user(optval, val, len))
		return -EFAULT;

	return 0;
}

static struct ccid_operations ccid3 = {
	.ccid_id		   = 3,
	.ccid_name		   = "ccid3",
	.ccid_owner		   = THIS_MODULE,
	.ccid_hc_tx_obj_size	   = sizeof(struct ccid3_hc_tx_sock),
	.ccid_hc_tx_init	   = ccid3_hc_tx_init,
	.ccid_hc_tx_exit	   = ccid3_hc_tx_exit,
	.ccid_hc_tx_send_packet	   = ccid3_hc_tx_send_packet,
	.ccid_hc_tx_packet_sent	   = ccid3_hc_tx_packet_sent,
	.ccid_hc_tx_packet_recv	   = ccid3_hc_tx_packet_recv,
	.ccid_hc_tx_insert_options = ccid3_hc_tx_insert_options,
	.ccid_hc_tx_parse_options  = ccid3_hc_tx_parse_options,
	.ccid_hc_rx_obj_size	   = sizeof(struct ccid3_hc_rx_sock),
	.ccid_hc_rx_init	   = ccid3_hc_rx_init,
	.ccid_hc_rx_exit	   = ccid3_hc_rx_exit,
	.ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options,
	.ccid_hc_rx_packet_recv	   = ccid3_hc_rx_packet_recv,
	.ccid_hc_rx_get_info	   = ccid3_hc_rx_get_info,
	.ccid_hc_tx_get_info	   = ccid3_hc_tx_get_info,
	.ccid_hc_rx_getsockopt	   = ccid3_hc_rx_getsockopt,
	.ccid_hc_tx_getsockopt	   = ccid3_hc_tx_getsockopt,
};
 
module_param(ccid3_debug, int, 0444);
MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");

static __init int ccid3_module_init(void)
{
	int rc = -ENOBUFS;

	ccid3_rx_hist = dccp_rx_hist_new("ccid3");
	if (ccid3_rx_hist == NULL)
		goto out;

	ccid3_tx_hist = dccp_tx_hist_new("ccid3");
	if (ccid3_tx_hist == NULL)
		goto out_free_rx;

	ccid3_li_hist = dccp_li_hist_new("ccid3");
	if (ccid3_li_hist == NULL)
		goto out_free_tx;

	rc = ccid_register(&ccid3);
	if (rc != 0) 
		goto out_free_loss_interval_history;
out:
	return rc;

out_free_loss_interval_history:
	dccp_li_hist_delete(ccid3_li_hist);
	ccid3_li_hist = NULL;
out_free_tx:
	dccp_tx_hist_delete(ccid3_tx_hist);
	ccid3_tx_hist = NULL;
out_free_rx:
	dccp_rx_hist_delete(ccid3_rx_hist);
	ccid3_rx_hist = NULL;
	goto out;
}
module_init(ccid3_module_init);

static __exit void ccid3_module_exit(void)
{
	ccid_unregister(&ccid3);

	if (ccid3_tx_hist != NULL) {
		dccp_tx_hist_delete(ccid3_tx_hist);
		ccid3_tx_hist = NULL;
	}
	if (ccid3_rx_hist != NULL) {
		dccp_rx_hist_delete(ccid3_rx_hist);
		ccid3_rx_hist = NULL;
	}
	if (ccid3_li_hist != NULL) {
		dccp_li_hist_delete(ccid3_li_hist);
		ccid3_li_hist = NULL;
	}
}
module_exit(ccid3_module_exit);

MODULE_AUTHOR("Ian McDonald <[e-mail]>, "
	      "Arnaldo Carvalho de Melo <[e-mail]>");
MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
MODULE_LICENSE("GPL");
MODULE_ALIAS("net-dccp-ccid-3");