[net-next-2.6.git] / net / dccp / output.c

/*
 *  net/dccp/output.c
 * 
 *  An implementation of the DCCP protocol
 *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

#include <linux/config.h>
#include <linux/dccp.h>
#include <linux/skbuff.h>

#include <net/sock.h>

#include "ackvec.h"
#include "ccid.h"
#include "dccp.h"

static inline void dccp_event_ack_sent(struct sock *sk)
{
	inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
}

/*
 * All SKB's seen here are completely headerless. It is our
 * job to build the DCCP header, and pass the packet down to
 * IP so it can do the same plus pass the packet off to the
 * device.
 */
int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
{
	if (likely(skb != NULL)) {
		const struct inet_sock *inet = inet_sk(sk);
		struct dccp_sock *dp = dccp_sk(sk);
		struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
		struct dccp_hdr *dh;
		/* XXX For now we're using only 48 bits sequence numbers */
		const int dccp_header_size = sizeof(*dh) +
					     sizeof(struct dccp_hdr_ext) +
					  dccp_packet_hdr_len(dcb->dccpd_type);
		int err, set_ack = 1;
		u64 ackno = dp->dccps_gsr;

		dccp_inc_seqno(&dp->dccps_gss);

		switch (dcb->dccpd_type) {
		case DCCP_PKT_DATA:
			set_ack = 0;
			break;
		case DCCP_PKT_SYNC:
		case DCCP_PKT_SYNCACK:
			ackno = dcb->dccpd_seq;
			break;
		}

		dcb->dccpd_seq = dp->dccps_gss;
		dccp_insert_options(sk, skb);
		
		skb->h.raw = skb_push(skb, dccp_header_size);
		dh = dccp_hdr(skb);

		if (!skb->sk)
			skb_set_owner_w(skb, sk);

		/* Build DCCP header and checksum it. */
		memset(dh, 0, dccp_header_size);
		dh->dccph_type	= dcb->dccpd_type;
		dh->dccph_sport	= inet->sport;
		dh->dccph_dport	= inet->dport;
		dh->dccph_doff	= (dccp_header_size + dcb->dccpd_opt_len) / 4;
		dh->dccph_ccval	= dcb->dccpd_ccval;
		/* XXX For now we're using only 48 bits sequence numbers */
		dh->dccph_x	= 1;

		dp->dccps_awh = dp->dccps_gss;
		dccp_hdr_set_seq(dh, dp->dccps_gss);
		if (set_ack)
			dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);

		switch (dcb->dccpd_type) {
		case DCCP_PKT_REQUEST:
			dccp_hdr_request(skb)->dccph_req_service =
							dp->dccps_service;
			break;
		case DCCP_PKT_RESET:
			dccp_hdr_reset(skb)->dccph_reset_code =
							dcb->dccpd_reset_code;
			break;
		}

		dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr,
						      inet->daddr);

		if (set_ack)
			dccp_event_ack_sent(sk);

		DCCP_INC_STATS(DCCP_MIB_OUTSEGS);

		err = ip_queue_xmit(skb, 0);
		if (err <= 0)
			return err;

		/* NET_XMIT_CN is special. It does not guarantee,
		 * that this packet is lost. It tells that device
		 * is about to start to drop packets or already
		 * drops some packets of the same priority and
		 * invokes us to send less aggressively.
		 */
		return err == NET_XMIT_CN ? 0 : err;
	}
	return -ENOBUFS;
}

unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
{
	struct dccp_sock *dp = dccp_sk(sk);
	int mss_now;

	/*
	 * FIXME: we really should be using the af_specific thing to support
	 * 	  IPv6.
	 * mss_now = pmtu - tp->af_specific->net_header_len -
	 * 	     sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
	 */
	mss_now = pmtu - sizeof(struct iphdr) - sizeof(struct dccp_hdr) -
		  sizeof(struct dccp_hdr_ext);

	/* Now subtract optional transport overhead */
	mss_now -= dp->dccps_ext_header_len;

	/*
	 * FIXME: this should come from the CCID infrastructure, where, say,
	 * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
	 * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
	 * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
	 * make it a multiple of 4
	 */

	mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;

	/* And store cached results */
	dp->dccps_pmtu_cookie = pmtu;
	dp->dccps_mss_cache = mss_now;

	return mss_now;
}

void dccp_write_space(struct sock *sk)
{
	read_lock(&sk->sk_callback_lock);

	if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
		wake_up_interruptible(sk->sk_sleep);
	/* Should agree with poll, otherwise some programs break */
	if (sock_writeable(sk))
		sk_wake_async(sk, 2, POLL_OUT);

	read_unlock(&sk->sk_callback_lock);
}

/**
 * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
 * @sk: socket to wait for
 * @timeo: for how long
 */
static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb,
			      long *timeo)
{
	struct dccp_sock *dp = dccp_sk(sk);
	DEFINE_WAIT(wait);
	long delay;
	int rc;

	while (1) {
		prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);

		if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
			goto do_error;
		if (!*timeo)
			goto do_nonblock;
		if (signal_pending(current))
			goto do_interrupted;

		rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
					    skb->len);
		if (rc <= 0)
			break;
		delay = msecs_to_jiffies(rc);
		if (delay > *timeo || delay < 0)
			goto do_nonblock;

		sk->sk_write_pending++;
		release_sock(sk);
		*timeo -= schedule_timeout(delay);
		lock_sock(sk);
		sk->sk_write_pending--;
	}
out:
	finish_wait(sk->sk_sleep, &wait);
	return rc;

do_error:
	rc = -EPIPE;
	goto out;
do_nonblock:
	rc = -EAGAIN;
	goto out;
do_interrupted:
	rc = sock_intr_errno(*timeo);
	goto out;
}

int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, long *timeo)
{
	const struct dccp_sock *dp = dccp_sk(sk);
	int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
					 skb->len);

	if (err > 0)
		err = dccp_wait_for_ccid(sk, skb, timeo);

	if (err == 0) {
		struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
		const int len = skb->len;

		if (sk->sk_state == DCCP_PARTOPEN) {
			/* See 8.1.5.  Handshake Completion */
			inet_csk_schedule_ack(sk);
			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
						  inet_csk(sk)->icsk_rto,
						  DCCP_RTO_MAX);
			dcb->dccpd_type = DCCP_PKT_DATAACK;
		} else if (dccp_ack_pending(sk))
			dcb->dccpd_type = DCCP_PKT_DATAACK;
		else
			dcb->dccpd_type = DCCP_PKT_DATA;

		err = dccp_transmit_skb(sk, skb);
		ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
	} else
		kfree_skb(skb);

	return err;
}

int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
{
	if (inet_sk_rebuild_header(sk) != 0)
		return -EHOSTUNREACH; /* Routing failure or similar. */

	return dccp_transmit_skb(sk, (skb_cloned(skb) ?
				      pskb_copy(skb, GFP_ATOMIC):
				      skb_clone(skb, GFP_ATOMIC)));
}

struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
				   struct request_sock *req)
{
	struct dccp_hdr *dh;
	struct dccp_request_sock *dreq;
	const int dccp_header_size = sizeof(struct dccp_hdr) +
				     sizeof(struct dccp_hdr_ext) +
				     sizeof(struct dccp_hdr_response);
	struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
					       dccp_header_size, 1,
					   GFP_ATOMIC);
	if (skb == NULL)
		return NULL;

	/* Reserve space for headers. */
	skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);

	skb->dst = dst_clone(dst);
	skb->csum = 0;

	dreq = dccp_rsk(req);
	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
	DCCP_SKB_CB(skb)->dccpd_seq  = dreq->dreq_iss;
	dccp_insert_options(sk, skb);

	skb->h.raw = skb_push(skb, dccp_header_size);

	dh = dccp_hdr(skb);
	memset(dh, 0, dccp_header_size);

	dh->dccph_sport	= inet_sk(sk)->sport;
	dh->dccph_dport	= inet_rsk(req)->rmt_port;
	dh->dccph_doff	= (dccp_header_size +
			   DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
	dh->dccph_type	= DCCP_PKT_RESPONSE;
	dh->dccph_x	= 1;
	dccp_hdr_set_seq(dh, dreq->dreq_iss);
	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr);
	dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service;

	dh->dccph_checksum = dccp_v4_checksum(skb, inet_rsk(req)->loc_addr,
					      inet_rsk(req)->rmt_addr);

	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	return skb;
}

struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst,
				const enum dccp_reset_codes code)
				   
{
	struct dccp_hdr *dh;
	struct dccp_sock *dp = dccp_sk(sk);
	const int dccp_header_size = sizeof(struct dccp_hdr) +
				     sizeof(struct dccp_hdr_ext) +
				     sizeof(struct dccp_hdr_reset);
	struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
					       dccp_header_size, 1,
					   GFP_ATOMIC);
	if (skb == NULL)
		return NULL;

	/* Reserve space for headers. */
	skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);

	skb->dst = dst_clone(dst);
	skb->csum = 0;

	dccp_inc_seqno(&dp->dccps_gss);

	DCCP_SKB_CB(skb)->dccpd_reset_code = code;
	DCCP_SKB_CB(skb)->dccpd_type	   = DCCP_PKT_RESET;
	DCCP_SKB_CB(skb)->dccpd_seq	   = dp->dccps_gss;
	dccp_insert_options(sk, skb);

	skb->h.raw = skb_push(skb, dccp_header_size);

	dh = dccp_hdr(skb);
	memset(dh, 0, dccp_header_size);

	dh->dccph_sport	= inet_sk(sk)->sport;
	dh->dccph_dport	= inet_sk(sk)->dport;
	dh->dccph_doff	= (dccp_header_size +
			   DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
	dh->dccph_type	= DCCP_PKT_RESET;
	dh->dccph_x	= 1;
	dccp_hdr_set_seq(dh, dp->dccps_gss);
	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);

	dccp_hdr_reset(skb)->dccph_reset_code = code;

	dh->dccph_checksum = dccp_v4_checksum(skb, inet_sk(sk)->saddr,
					      inet_sk(sk)->daddr);

	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	return skb;
}

/*
 * Do all connect socket setups that can be done AF independent.
 */
static inline void dccp_connect_init(struct sock *sk)
{
	struct dst_entry *dst = __sk_dst_get(sk);
	struct inet_connection_sock *icsk = inet_csk(sk);

	sk->sk_err = 0;
	sock_reset_flag(sk, SOCK_DONE);
	
	dccp_sync_mss(sk, dst_mtu(dst));

	/*
	 * FIXME: set dp->{dccps_swh,dccps_swl}, with
	 * something like dccp_inc_seq
	 */

	icsk->icsk_retransmits = 0;
}

int dccp_connect(struct sock *sk)
{
	struct sk_buff *skb;
	struct inet_connection_sock *icsk = inet_csk(sk);

	dccp_connect_init(sk);

	skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation);
	if (unlikely(skb == NULL))
		return -ENOBUFS;

	/* Reserve space for headers. */
	skb_reserve(skb, MAX_DCCP_HEADER);

	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
	skb->csum = 0;
	skb_set_owner_w(skb, sk);

	BUG_TRAP(sk->sk_send_head == NULL);
	sk->sk_send_head = skb;
	dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
	DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);

	/* Timer for repeating the REQUEST until an answer. */
	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
				  icsk->icsk_rto, DCCP_RTO_MAX);
	return 0;
}

void dccp_send_ack(struct sock *sk)
{
	/* If we have been reset, we may not send again. */
	if (sk->sk_state != DCCP_CLOSED) {
		struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);

		if (skb == NULL) {
			inet_csk_schedule_ack(sk);
			inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
						  TCP_DELACK_MAX,
						  DCCP_RTO_MAX);
			return;
		}

		/* Reserve space for headers */
		skb_reserve(skb, MAX_DCCP_HEADER);
		skb->csum = 0;
		DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
		skb_set_owner_w(skb, sk);
		dccp_transmit_skb(sk, skb);
	}
}

EXPORT_SYMBOL_GPL(dccp_send_ack);

void dccp_send_delayed_ack(struct sock *sk)
{
	struct inet_connection_sock *icsk = inet_csk(sk);
	/*
	 * FIXME: tune this timer. elapsed time fixes the skew, so no problem
	 * with using 2s, and active senders also piggyback the ACK into a
	 * DATAACK packet, so this is really for quiescent senders.
	 */
	unsigned long timeout = jiffies + 2 * HZ;

	/* Use new timeout only if there wasn't a older one earlier. */
	if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
		/* If delack timer was blocked or is about to expire,
		 * send ACK now.
		 *
		 * FIXME: check the "about to expire" part
		 */
		if (icsk->icsk_ack.blocked) {
			dccp_send_ack(sk);
			return;
		}

		if (!time_before(timeout, icsk->icsk_ack.timeout))
			timeout = icsk->icsk_ack.timeout;
	}
	icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
	icsk->icsk_ack.timeout = timeout;
	sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
}

void dccp_send_sync(struct sock *sk, const u64 seq,
		    const enum dccp_pkt_type pkt_type)
{
	/*
	 * We are not putting this on the write queue, so
	 * dccp_transmit_skb() will set the ownership to this
	 * sock.
	 */
	struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);

	if (skb == NULL)
		/* FIXME: how to make sure the sync is sent? */
		return;

	/* Reserve space for headers and prepare control bits. */
	skb_reserve(skb, MAX_DCCP_HEADER);
	skb->csum = 0;
	DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
	DCCP_SKB_CB(skb)->dccpd_seq = seq;

	skb_set_owner_w(skb, sk);
	dccp_transmit_skb(sk, skb);
}

/*
 * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
 * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
 * any circumstances.
 */
void dccp_send_close(struct sock *sk, const int active)
{
	struct dccp_sock *dp = dccp_sk(sk);
	struct sk_buff *skb;
	const unsigned int prio = active ? GFP_KERNEL : GFP_ATOMIC;

	skb = alloc_skb(sk->sk_prot->max_header, prio);
	if (skb == NULL)
		return;

	/* Reserve space for headers and prepare control bits. */
	skb_reserve(skb, sk->sk_prot->max_header);
	skb->csum = 0;
	DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
					DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;

	skb_set_owner_w(skb, sk);
	if (active) {
		BUG_TRAP(sk->sk_send_head == NULL);
		sk->sk_send_head = skb;
		dccp_transmit_skb(sk, skb_clone(skb, prio));
	} else
		dccp_transmit_skb(sk, skb);
}
Commit	Line	Data
7c657876 ACM	1	/*
	2	* net/dccp/output.c
	3	*
	4	* An implementation of the DCCP protocol
	5	* Arnaldo Carvalho de Melo <acme@conectiva.com.br>
	6	*
	7	* This program is free software; you can redistribute it and/or
	8	* modify it under the terms of the GNU General Public License
	9	* as published by the Free Software Foundation; either version
	10	* 2 of the License, or (at your option) any later version.
	11	*/
	12
	13	#include <linux/config.h>
	14	#include <linux/dccp.h>
	15	#include <linux/skbuff.h>
	16
	17	#include <net/sock.h>
	18
ae31c339	19	#include "ackvec.h"
7c657876 ACM	20	#include "ccid.h"
	21	#include "dccp.h"
	22
	23	static inline void dccp_event_ack_sent(struct sock *sk)
	24	{
	25	inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
	26	}
	27
	28	/*
	29	* All SKB's seen here are completely headerless. It is our
	30	* job to build the DCCP header, and pass the packet down to
	31	* IP so it can do the same plus pass the packet off to the
	32	* device.
	33	*/
	34	int dccp_transmit_skb(struct sock sk, struct sk_buff skb)
	35	{
	36	if (likely(skb != NULL)) {
	37	const struct inet_sock *inet = inet_sk(sk);
	38	struct dccp_sock *dp = dccp_sk(sk);
	39	struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
	40	struct dccp_hdr *dh;
	41	/* XXX For now we're using only 48 bits sequence numbers */
	42	const int dccp_header_size = sizeof(*dh) +
	43	sizeof(struct dccp_hdr_ext) +
7690af3f	44	dccp_packet_hdr_len(dcb->dccpd_type);
7c657876 ACM	45	int err, set_ack = 1;
	46	u64 ackno = dp->dccps_gsr;
	47
7c657876 ACM	48	dccp_inc_seqno(&dp->dccps_gss);
7c657876 ACM	49
7c657876 ACM	50	switch (dcb->dccpd_type) {
	51	case DCCP_PKT_DATA:
	52	set_ack = 0;
	53	break;
	54	case DCCP_PKT_SYNC:
	55	case DCCP_PKT_SYNCACK:
	56	ackno = dcb->dccpd_seq;
	57	break;
	58	}
24117727 ACM	59
	60	dcb->dccpd_seq = dp->dccps_gss;
	61	dccp_insert_options(sk, skb);
7c657876 ACM	62
	63	skb->h.raw = skb_push(skb, dccp_header_size);
	64	dh = dccp_hdr(skb);
fda0fd6c HX	65
fda0fd6c HX	66	if (!skb->sk)
7c657876 ACM	67	skb_set_owner_w(skb, sk);
	68
	69	/* Build DCCP header and checksum it. */
	70	memset(dh, 0, dccp_header_size);
	71	dh->dccph_type = dcb->dccpd_type;
	72	dh->dccph_sport = inet->sport;
	73	dh->dccph_dport = inet->dport;
	74	dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4;
	75	dh->dccph_ccval = dcb->dccpd_ccval;
	76	/* XXX For now we're using only 48 bits sequence numbers */
	77	dh->dccph_x = 1;
	78
	79	dp->dccps_awh = dp->dccps_gss;
	80	dccp_hdr_set_seq(dh, dp->dccps_gss);
	81	if (set_ack)
	82	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
	83
	84	switch (dcb->dccpd_type) {
	85	case DCCP_PKT_REQUEST:
7690af3f	86	dccp_hdr_request(skb)->dccph_req_service =
67e6b629	87	dp->dccps_service;
7c657876 ACM	88	break;
7c657876 ACM	89	case DCCP_PKT_RESET:
7690af3f ACM	90	dccp_hdr_reset(skb)->dccph_reset_code =
7690af3f ACM	91	dcb->dccpd_reset_code;
7c657876 ACM	92	break;
	93	}
	94
95b81ef7 YN	95	dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr,
95b81ef7 YN	96	inet->daddr);
7c657876	97
7ad07e7c	98	if (set_ack)
7c657876 ACM	99	dccp_event_ack_sent(sk);
	100
	101	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	102
	103	err = ip_queue_xmit(skb, 0);
	104	if (err <= 0)
	105	return err;
	106
	107	/* NET_XMIT_CN is special. It does not guarantee,
	108	* that this packet is lost. It tells that device
	109	* is about to start to drop packets or already
	110	* drops some packets of the same priority and
	111	* invokes us to send less aggressively.
	112	*/
	113	return err == NET_XMIT_CN ? 0 : err;
	114	}
	115	return -ENOBUFS;
	116	}
	117
	118	unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
	119	{
	120	struct dccp_sock *dp = dccp_sk(sk);
	121	int mss_now;
	122
	123	/*
7690af3f ACM	124	* FIXME: we really should be using the af_specific thing to support
	125	* IPv6.
	126	* mss_now = pmtu - tp->af_specific->net_header_len -
	127	* sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
7c657876	128	*/
7690af3f ACM	129	mss_now = pmtu - sizeof(struct iphdr) - sizeof(struct dccp_hdr) -
7690af3f ACM	130	sizeof(struct dccp_hdr_ext);
7c657876 ACM	131
	132	/* Now subtract optional transport overhead */
	133	mss_now -= dp->dccps_ext_header_len;
	134
	135	/*
	136	* FIXME: this should come from the CCID infrastructure, where, say,
	137	* TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
	138	* put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
	139	* TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
	140	* make it a multiple of 4
	141	*/
	142
	143	mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
	144
	145	/* And store cached results */
	146	dp->dccps_pmtu_cookie = pmtu;
	147	dp->dccps_mss_cache = mss_now;
	148
	149	return mss_now;
	150	}
	151
c530cfb1 ACM	152	void dccp_write_space(struct sock *sk)
	153	{
	154	read_lock(&sk->sk_callback_lock);
	155
	156	if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
	157	wake_up_interruptible(sk->sk_sleep);
	158	/* Should agree with poll, otherwise some programs break */
	159	if (sock_writeable(sk))
	160	sk_wake_async(sk, 2, POLL_OUT);
	161
	162	read_unlock(&sk->sk_callback_lock);
	163	}
	164
d6809c12 ACM	165	/**
	166	* dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
	167	* @sk: socket to wait for
	168	* @timeo: for how long
	169	*/
	170	static int dccp_wait_for_ccid(struct sock sk, struct sk_buff skb,
	171	long *timeo)
	172	{
	173	struct dccp_sock *dp = dccp_sk(sk);
	174	DEFINE_WAIT(wait);
	175	long delay;
	176	int rc;
	177
	178	while (1) {
	179	prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
	180
	181	if (sk->sk_err \|\| (sk->sk_shutdown & SEND_SHUTDOWN))
	182	goto do_error;
	183	if (!*timeo)
	184	goto do_nonblock;
	185	if (signal_pending(current))
	186	goto do_interrupted;
	187
	188	rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
	189	skb->len);
	190	if (rc <= 0)
	191	break;
	192	delay = msecs_to_jiffies(rc);
	193	if (delay > *timeo \|\| delay < 0)
	194	goto do_nonblock;
	195
	196	sk->sk_write_pending++;
	197	release_sock(sk);
	198	*timeo -= schedule_timeout(delay);
	199	lock_sock(sk);
	200	sk->sk_write_pending--;
	201	}
	202	out:
	203	finish_wait(sk->sk_sleep, &wait);
	204	return rc;
	205
	206	do_error:
	207	rc = -EPIPE;
	208	goto out;
	209	do_nonblock:
	210	rc = -EAGAIN;
	211	goto out;
	212	do_interrupted:
	213	rc = sock_intr_errno(*timeo);
	214	goto out;
	215	}
	216
	217	int dccp_write_xmit(struct sock sk, struct sk_buff skb, long *timeo)
27258ee5 ACM	218	{
27258ee5 ACM	219	const struct dccp_sock *dp = dccp_sk(sk);
d6809c12 ACM	220	int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
	221	skb->len);
	222
	223	if (err > 0)
	224	err = dccp_wait_for_ccid(sk, skb, timeo);
27258ee5 ACM	225
27258ee5 ACM	226	if (err == 0) {
27258ee5	227	struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
d6809c12	228	const int len = skb->len;
27258ee5 ACM	229
	230	if (sk->sk_state == DCCP_PARTOPEN) {
	231	/* See 8.1.5. Handshake Completion */
	232	inet_csk_schedule_ack(sk);
	233	inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
	234	inet_csk(sk)->icsk_rto,
	235	DCCP_RTO_MAX);
	236	dcb->dccpd_type = DCCP_PKT_DATAACK;
ae31c339	237	} else if (dccp_ack_pending(sk))
27258ee5 ACM	238	dcb->dccpd_type = DCCP_PKT_DATAACK;
	239	else
	240	dcb->dccpd_type = DCCP_PKT_DATA;
	241
	242	err = dccp_transmit_skb(sk, skb);
	243	ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
ffa29347 HX	244	} else
ffa29347 HX	245	kfree_skb(skb);
27258ee5 ACM	246
	247	return err;
	248	}
	249
7c657876 ACM	250	int dccp_retransmit_skb(struct sock sk, struct sk_buff skb)
	251	{
	252	if (inet_sk_rebuild_header(sk) != 0)
	253	return -EHOSTUNREACH; /* Routing failure or similar. */
	254
	255	return dccp_transmit_skb(sk, (skb_cloned(skb) ?
	256	pskb_copy(skb, GFP_ATOMIC):
	257	skb_clone(skb, GFP_ATOMIC)));
	258	}
	259
	260	struct sk_buff dccp_make_response(struct sock sk, struct dst_entry *dst,
	261	struct request_sock *req)
	262	{
	263	struct dccp_hdr *dh;
67e6b629	264	struct dccp_request_sock *dreq;
7c657876 ACM	265	const int dccp_header_size = sizeof(struct dccp_hdr) +
	266	sizeof(struct dccp_hdr_ext) +
	267	sizeof(struct dccp_hdr_response);
	268	struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
	269	dccp_header_size, 1,
	270	GFP_ATOMIC);
	271	if (skb == NULL)
	272	return NULL;
	273
	274	/* Reserve space for headers. */
	275	skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
	276
	277	skb->dst = dst_clone(dst);
	278	skb->csum = 0;
	279
67e6b629	280	dreq = dccp_rsk(req);
7c657876	281	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
67e6b629	282	DCCP_SKB_CB(skb)->dccpd_seq = dreq->dreq_iss;
7c657876 ACM	283	dccp_insert_options(sk, skb);
	284
	285	skb->h.raw = skb_push(skb, dccp_header_size);
	286
	287	dh = dccp_hdr(skb);
	288	memset(dh, 0, dccp_header_size);
	289
	290	dh->dccph_sport = inet_sk(sk)->sport;
	291	dh->dccph_dport = inet_rsk(req)->rmt_port;
7690af3f ACM	292	dh->dccph_doff = (dccp_header_size +
7690af3f ACM	293	DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
7c657876 ACM	294	dh->dccph_type = DCCP_PKT_RESPONSE;
7c657876 ACM	295	dh->dccph_x = 1;
67e6b629 ACM	296	dccp_hdr_set_seq(dh, dreq->dreq_iss);
	297	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr);
	298	dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service;
7c657876	299
95b81ef7 YN	300	dh->dccph_checksum = dccp_v4_checksum(skb, inet_rsk(req)->loc_addr,
95b81ef7 YN	301	inet_rsk(req)->rmt_addr);
7c657876 ACM	302
	303	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	304	return skb;
	305	}
	306
	307	struct sk_buff dccp_make_reset(struct sock sk, struct dst_entry *dst,
	308	const enum dccp_reset_codes code)
	309
	310	{
	311	struct dccp_hdr *dh;
	312	struct dccp_sock *dp = dccp_sk(sk);
	313	const int dccp_header_size = sizeof(struct dccp_hdr) +
	314	sizeof(struct dccp_hdr_ext) +
	315	sizeof(struct dccp_hdr_reset);
	316	struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
	317	dccp_header_size, 1,
	318	GFP_ATOMIC);
	319	if (skb == NULL)
	320	return NULL;
	321
	322	/* Reserve space for headers. */
	323	skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
	324
	325	skb->dst = dst_clone(dst);
	326	skb->csum = 0;
	327
	328	dccp_inc_seqno(&dp->dccps_gss);
	329
	330	DCCP_SKB_CB(skb)->dccpd_reset_code = code;
	331	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET;
	332	DCCP_SKB_CB(skb)->dccpd_seq = dp->dccps_gss;
	333	dccp_insert_options(sk, skb);
	334
	335	skb->h.raw = skb_push(skb, dccp_header_size);
	336
	337	dh = dccp_hdr(skb);
	338	memset(dh, 0, dccp_header_size);
	339
	340	dh->dccph_sport = inet_sk(sk)->sport;
	341	dh->dccph_dport = inet_sk(sk)->dport;
7690af3f ACM	342	dh->dccph_doff = (dccp_header_size +
7690af3f ACM	343	DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
7c657876 ACM	344	dh->dccph_type = DCCP_PKT_RESET;
	345	dh->dccph_x = 1;
	346	dccp_hdr_set_seq(dh, dp->dccps_gss);
	347	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
	348
	349	dccp_hdr_reset(skb)->dccph_reset_code = code;
	350
95b81ef7 YN	351	dh->dccph_checksum = dccp_v4_checksum(skb, inet_sk(sk)->saddr,
95b81ef7 YN	352	inet_sk(sk)->daddr);
7c657876 ACM	353
	354	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	355	return skb;
	356	}
	357
	358	/*
	359	* Do all connect socket setups that can be done AF independent.
	360	*/
	361	static inline void dccp_connect_init(struct sock *sk)
	362	{
	363	struct dst_entry *dst = __sk_dst_get(sk);
	364	struct inet_connection_sock *icsk = inet_csk(sk);
	365
	366	sk->sk_err = 0;
	367	sock_reset_flag(sk, SOCK_DONE);
	368
	369	dccp_sync_mss(sk, dst_mtu(dst));
	370
	371	/*
	372	* FIXME: set dp->{dccps_swh,dccps_swl}, with
	373	* something like dccp_inc_seq
	374	*/
	375
	376	icsk->icsk_retransmits = 0;
	377	}
	378
	379	int dccp_connect(struct sock *sk)
	380	{
	381	struct sk_buff *skb;
	382	struct inet_connection_sock *icsk = inet_csk(sk);
	383
	384	dccp_connect_init(sk);
	385
	386	skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation);
	387	if (unlikely(skb == NULL))
	388	return -ENOBUFS;
	389
	390	/* Reserve space for headers. */
	391	skb_reserve(skb, MAX_DCCP_HEADER);
	392
	393	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
7c657876 ACM	394	skb->csum = 0;
	395	skb_set_owner_w(skb, sk);
	396
	397	BUG_TRAP(sk->sk_send_head == NULL);
	398	sk->sk_send_head = skb;
	399	dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
	400	DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
	401
	402	/* Timer for repeating the REQUEST until an answer. */
27258ee5 ACM	403	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
27258ee5 ACM	404	icsk->icsk_rto, DCCP_RTO_MAX);
7c657876 ACM	405	return 0;
	406	}
	407
	408	void dccp_send_ack(struct sock *sk)
	409	{
	410	/* If we have been reset, we may not send again. */
	411	if (sk->sk_state != DCCP_CLOSED) {
	412	struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
	413
	414	if (skb == NULL) {
	415	inet_csk_schedule_ack(sk);
	416	inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
7690af3f ACM	417	inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
	418	TCP_DELACK_MAX,
	419	DCCP_RTO_MAX);
7c657876 ACM	420	return;
	421	}
	422
	423	/* Reserve space for headers */
	424	skb_reserve(skb, MAX_DCCP_HEADER);
	425	skb->csum = 0;
	426	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
	427	skb_set_owner_w(skb, sk);
	428	dccp_transmit_skb(sk, skb);
	429	}
	430	}
	431
	432	EXPORT_SYMBOL_GPL(dccp_send_ack);
	433
	434	void dccp_send_delayed_ack(struct sock *sk)
	435	{
	436	struct inet_connection_sock *icsk = inet_csk(sk);
	437	/*
	438	* FIXME: tune this timer. elapsed time fixes the skew, so no problem
	439	* with using 2s, and active senders also piggyback the ACK into a
	440	* DATAACK packet, so this is really for quiescent senders.
	441	*/
	442	unsigned long timeout = jiffies + 2 * HZ;
	443
	444	/* Use new timeout only if there wasn't a older one earlier. */
	445	if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
	446	/* If delack timer was blocked or is about to expire,
	447	* send ACK now.
	448	*
	449	* FIXME: check the "about to expire" part
	450	*/
	451	if (icsk->icsk_ack.blocked) {
	452	dccp_send_ack(sk);
	453	return;
	454	}
	455
	456	if (!time_before(timeout, icsk->icsk_ack.timeout))
	457	timeout = icsk->icsk_ack.timeout;
	458	}
	459	icsk->icsk_ack.pending \|= ICSK_ACK_SCHED \| ICSK_ACK_TIMER;
	460	icsk->icsk_ack.timeout = timeout;
	461	sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
	462	}
	463
e92ae93a ACM	464	void dccp_send_sync(struct sock *sk, const u64 seq,
e92ae93a ACM	465	const enum dccp_pkt_type pkt_type)
7c657876 ACM	466	{
	467	/*
	468	* We are not putting this on the write queue, so
	469	* dccp_transmit_skb() will set the ownership to this
	470	* sock.
	471	*/
	472	struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
	473
	474	if (skb == NULL)
	475	/* FIXME: how to make sure the sync is sent? */
	476	return;
	477
	478	/* Reserve space for headers and prepare control bits. */
	479	skb_reserve(skb, MAX_DCCP_HEADER);
	480	skb->csum = 0;
e92ae93a	481	DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
7c657876 ACM	482	DCCP_SKB_CB(skb)->dccpd_seq = seq;
	483
	484	skb_set_owner_w(skb, sk);
	485	dccp_transmit_skb(sk, skb);
	486	}
	487
7690af3f ACM	488	/*
	489	* Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
	490	* cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
	491	* any circumstances.
7c657876	492	*/
7ad07e7c	493	void dccp_send_close(struct sock *sk, const int active)
7c657876 ACM	494	{
	495	struct dccp_sock *dp = dccp_sk(sk);
	496	struct sk_buff *skb;
7ad07e7c	497	const unsigned int prio = active ? GFP_KERNEL : GFP_ATOMIC;
7c657876	498
7ad07e7c ACM	499	skb = alloc_skb(sk->sk_prot->max_header, prio);
	500	if (skb == NULL)
	501	return;
7c657876 ACM	502
	503	/* Reserve space for headers and prepare control bits. */
	504	skb_reserve(skb, sk->sk_prot->max_header);
	505	skb->csum = 0;
7690af3f ACM	506	DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
7690af3f ACM	507	DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
7c657876 ACM	508
7c657876 ACM	509	skb_set_owner_w(skb, sk);
7ad07e7c ACM	510	if (active) {
	511	BUG_TRAP(sk->sk_send_head == NULL);
	512	sk->sk_send_head = skb;
	513	dccp_transmit_skb(sk, skb_clone(skb, prio));
	514	} else
	515	dccp_transmit_skb(sk, skb);
7c657876	516	}