ccid3.c

linux 内核源代码

	packet = dccp_rx_hist_find_data_packet(&hcrx->ccid3hcrx_hist);
	if (unlikely(packet == NULL)) {
		DCCP_WARN("%s(%p), no data packet in history!\n",
			  dccp_role(sk), sk);
		return;
	}

	hcrx->ccid3hcrx_tstamp_last_feedback = now;
	hcrx->ccid3hcrx_ccval_last_counter   = packet->dccphrx_ccval;
	hcrx->ccid3hcrx_bytes_recv	     = 0;

	/* Elapsed time information [RFC 4340, 13.2] in units of 10 * usecs */
	delta = ktime_us_delta(now, packet->dccphrx_tstamp);
	DCCP_BUG_ON(delta < 0);
	hcrx->ccid3hcrx_elapsed_time = delta / 10;

	if (hcrx->ccid3hcrx_p == 0)
		hcrx->ccid3hcrx_pinv = ~0U;	/* see RFC 4342, 8.5 */
	else if (hcrx->ccid3hcrx_p > 1000000) {
		DCCP_WARN("p (%u) > 100%%\n", hcrx->ccid3hcrx_p);
		hcrx->ccid3hcrx_pinv = 1;	/* use 100% in this case */
	} else
		hcrx->ccid3hcrx_pinv = 1000000 / hcrx->ccid3hcrx_p;

	dp->dccps_hc_rx_insert_options = 1;
	dccp_send_ack(sk);
}

static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
{
	const struct ccid3_hc_rx_sock *hcrx;
	__be32 x_recv, pinv;

	if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN))
		return 0;

	hcrx = ccid3_hc_rx_sk(sk);
	DCCP_SKB_CB(skb)->dccpd_ccval = hcrx->ccid3hcrx_ccval_last_counter;

	if (dccp_packet_without_ack(skb))
		return 0;

	x_recv = htonl(hcrx->ccid3hcrx_x_recv);
	pinv   = htonl(hcrx->ccid3hcrx_pinv);

	if ((hcrx->ccid3hcrx_elapsed_time != 0 &&
	     dccp_insert_option_elapsed_time(sk, skb,
					     hcrx->ccid3hcrx_elapsed_time)) ||
	    dccp_insert_option_timestamp(sk, skb) ||
	    dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE,
			       &pinv, sizeof(pinv)) ||
	    dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE,
			       &x_recv, sizeof(x_recv)))
		return -1;

	return 0;
}

static int ccid3_hc_rx_detect_loss(struct sock *sk,
				    struct dccp_rx_hist_entry *packet)
{
	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
	struct dccp_rx_hist_entry *rx_hist =
				dccp_rx_hist_head(&hcrx->ccid3hcrx_hist);
	u64 seqno = packet->dccphrx_seqno;
	u64 tmp_seqno;
	int loss = 0;
	u8 ccval;


	tmp_seqno = hcrx->ccid3hcrx_seqno_nonloss;

	if (!rx_hist ||
	   follows48(packet->dccphrx_seqno, hcrx->ccid3hcrx_seqno_nonloss)) {
		hcrx->ccid3hcrx_seqno_nonloss = seqno;
		hcrx->ccid3hcrx_ccval_nonloss = packet->dccphrx_ccval;
		goto detect_out;
	}


	while (dccp_delta_seqno(hcrx->ccid3hcrx_seqno_nonloss, seqno)
	   > TFRC_RECV_NUM_LATE_LOSS) {
		loss = 1;
		dccp_li_update_li(sk,
				  &hcrx->ccid3hcrx_li_hist,
				  &hcrx->ccid3hcrx_hist,
				  hcrx->ccid3hcrx_tstamp_last_feedback,
				  hcrx->ccid3hcrx_s,
				  hcrx->ccid3hcrx_bytes_recv,
				  hcrx->ccid3hcrx_x_recv,
				  hcrx->ccid3hcrx_seqno_nonloss,
				  hcrx->ccid3hcrx_ccval_nonloss);
		tmp_seqno = hcrx->ccid3hcrx_seqno_nonloss;
		dccp_inc_seqno(&tmp_seqno);
		hcrx->ccid3hcrx_seqno_nonloss = tmp_seqno;
		dccp_inc_seqno(&tmp_seqno);
		while (dccp_rx_hist_find_entry(&hcrx->ccid3hcrx_hist,
		   tmp_seqno, &ccval)) {
			hcrx->ccid3hcrx_seqno_nonloss = tmp_seqno;
			hcrx->ccid3hcrx_ccval_nonloss = ccval;
			dccp_inc_seqno(&tmp_seqno);
		}
	}

	/* FIXME - this code could be simplified with above while */
	/* but works at moment */
	if (follows48(packet->dccphrx_seqno, hcrx->ccid3hcrx_seqno_nonloss)) {
		hcrx->ccid3hcrx_seqno_nonloss = seqno;
		hcrx->ccid3hcrx_ccval_nonloss = packet->dccphrx_ccval;
	}

detect_out:
	dccp_rx_hist_add_packet(ccid3_rx_hist, &hcrx->ccid3hcrx_hist,
		   &hcrx->ccid3hcrx_li_hist, packet,
		   hcrx->ccid3hcrx_seqno_nonloss);
	return 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;
	u32 p_prev, r_sample, rtt_prev;
	int loss, payload_size;
	ktime_t now;

	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;
		r_sample = dccp_timestamp() - opt_recv->dccpor_timestamp_echo;
		rtt_prev = hcrx->ccid3hcrx_rtt;
		r_sample = dccp_sample_rtt(sk, 10 * r_sample);

		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 (rtt_prev != hcrx->ccid3hcrx_rtt)
			ccid3_pr_debug("%s(%p), New RTT=%uus, elapsed time=%u\n",
				       dccp_role(sk), 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, opt_recv->dccpor_ndp,
					skb, GFP_ATOMIC);
	if (unlikely(packet == NULL)) {
		DCCP_WARN("%s(%p), Not enough mem to add rx packet "
			  "to history, consider it lost!\n", dccp_role(sk), sk);
		return;
	}

	loss = ccid3_hc_rx_detect_loss(sk, packet);

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

	payload_size = skb->len - dccp_hdr(skb)->dccph_doff * 4;
	ccid3_hc_rx_update_s(hcrx, payload_size);

	switch (hcrx->ccid3hcrx_state) {
	case TFRC_RSTATE_NO_DATA:
		ccid3_pr_debug("%s(%p, state=%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 += payload_size;
		if (loss)
			break;

		now = ktime_get_real();
		if ((ktime_us_delta(now, hcrx->ccid3hcrx_tstamp_last_ack) -
		     (s64)hcrx->ccid3hcrx_rtt) >= 0) {
			hcrx->ccid3hcrx_tstamp_last_ack = now;
			ccid3_hc_rx_send_feedback(sk);
		}
		return;
	case TFRC_RSTATE_TERM:
		DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
		return;
	}

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

	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;
	} else
		DCCP_BUG("empty loss history");

	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 ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);

	ccid3_pr_debug("entry\n");

	hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
	INIT_LIST_HEAD(&hcrx->ccid3hcrx_hist);
	INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
	hcrx->ccid3hcrx_tstamp_last_feedback =
		hcrx->ccid3hcrx_tstamp_last_ack = ktime_get_real();
	return 0;
}

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

	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(&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;

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

	hcrx = ccid3_hc_rx_sk(sk);
	info->tcpi_ca_state = hcrx->ccid3hcrx_state;
	info->tcpi_options  |= TCPI_OPT_TIMESTAMPS;
	info->tcpi_rcv_rtt  = hcrx->ccid3hcrx_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;
	const void *val;

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

	hcrx = ccid3_hc_rx_sk(sk);
	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 struct ccid_operations ccid3 = {
	.ccid_id		   = DCCPC_CCID3,
	.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_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,
};

#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
module_param(ccid3_debug, bool, 0444);
MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");
#endif

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;

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

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;
	}
}
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");