[linux.git] / net / dccp / output.c

/*
 *  net/dccp/output.c
 * 
 *  An implementation of the DCCP protocol
 *  Arnaldo Carvalho de Melo <[email protected]>
 *
 *	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 "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);
		/*
		 * Data packets are not cloned as they are never retransmitted
		 */
		if (skb_cloned(skb))
			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 =
							dcb->dccpd_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) {
		const struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
		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;
			/*
			 * FIXME: we really should have a
			 * dccps_ack_pending or use icsk.
			 */
		} else if (inet_csk_ack_scheduled(sk) ||
			   dp->dccps_timestamp_echo != 0 ||
			   (dp->dccps_options.dccpo_send_ack_vector &&
			    ap->dccpap_buf_ackno != DCCP_MAX_SEQNO + 1 &&
			    ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1))
			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);
	}

	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;
	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;

	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
	DCCP_SKB_CB(skb)->dccpd_seq  = dccp_rsk(req)->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, dccp_rsk(req)->dreq_iss);
	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dccp_rsk(req)->dreq_isr);

	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;
	/* FIXME: set service to something meaningful, coming
	 * from userspace*/
	DCCP_SKB_CB(skb)->dccpd_service = 0;
	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 <[email protected]>
	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
	19	#include "ccid.h"
	20	#include "dccp.h"
	21
	22	static inline void dccp_event_ack_sent(struct sock *sk)
	23	{
	24	inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
	25	}
	26
	27	/*
	28	* All SKB's seen here are completely headerless. It is our
	29	* job to build the DCCP header, and pass the packet down to
	30	* IP so it can do the same plus pass the packet off to the
	31	* device.
	32	*/
	33	int dccp_transmit_skb(struct sock sk, struct sk_buff skb)
	34	{
	35	if (likely(skb != NULL)) {
	36	const struct inet_sock *inet = inet_sk(sk);
	37	struct dccp_sock *dp = dccp_sk(sk);
	38	struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
	39	struct dccp_hdr *dh;
	40	/* XXX For now we're using only 48 bits sequence numbers */
	41	const int dccp_header_size = sizeof(*dh) +
	42	sizeof(struct dccp_hdr_ext) +
7690af3f	43	dccp_packet_hdr_len(dcb->dccpd_type);
7c657876 ACM	44	int err, set_ack = 1;
	45	u64 ackno = dp->dccps_gsr;
	46
7c657876 ACM	47	dccp_inc_seqno(&dp->dccps_gss);
7c657876 ACM	48
7c657876 ACM	49	switch (dcb->dccpd_type) {
	50	case DCCP_PKT_DATA:
	51	set_ack = 0;
	52	break;
	53	case DCCP_PKT_SYNC:
	54	case DCCP_PKT_SYNCACK:
	55	ackno = dcb->dccpd_seq;
	56	break;
	57	}
24117727 ACM	58
	59	dcb->dccpd_seq = dp->dccps_gss;
	60	dccp_insert_options(sk, skb);
7c657876 ACM	61
	62	skb->h.raw = skb_push(skb, dccp_header_size);
	63	dh = dccp_hdr(skb);
7690af3f ACM	64	/*
	65	* Data packets are not cloned as they are never retransmitted
	66	*/
7c657876 ACM	67	if (skb_cloned(skb))
	68	skb_set_owner_w(skb, sk);
	69
	70	/* Build DCCP header and checksum it. */
	71	memset(dh, 0, dccp_header_size);
	72	dh->dccph_type = dcb->dccpd_type;
	73	dh->dccph_sport = inet->sport;
	74	dh->dccph_dport = inet->dport;
	75	dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4;
	76	dh->dccph_ccval = dcb->dccpd_ccval;
	77	/* XXX For now we're using only 48 bits sequence numbers */
	78	dh->dccph_x = 1;
	79
	80	dp->dccps_awh = dp->dccps_gss;
	81	dccp_hdr_set_seq(dh, dp->dccps_gss);
	82	if (set_ack)
	83	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
	84
	85	switch (dcb->dccpd_type) {
	86	case DCCP_PKT_REQUEST:
7690af3f ACM	87	dccp_hdr_request(skb)->dccph_req_service =
7690af3f ACM	88	dcb->dccpd_service;
7c657876 ACM	89	break;
7c657876 ACM	90	case DCCP_PKT_RESET:
7690af3f ACM	91	dccp_hdr_reset(skb)->dccph_reset_code =
7690af3f ACM	92	dcb->dccpd_reset_code;
7c657876 ACM	93	break;
	94	}
	95
95b81ef7 YN	96	dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr,
95b81ef7 YN	97	inet->daddr);
7c657876	98
7ad07e7c	99	if (set_ack)
7c657876 ACM	100	dccp_event_ack_sent(sk);
	101
	102	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	103
	104	err = ip_queue_xmit(skb, 0);
	105	if (err <= 0)
	106	return err;
	107
	108	/* NET_XMIT_CN is special. It does not guarantee,
	109	* that this packet is lost. It tells that device
	110	* is about to start to drop packets or already
	111	* drops some packets of the same priority and
	112	* invokes us to send less aggressively.
	113	*/
	114	return err == NET_XMIT_CN ? 0 : err;
	115	}
	116	return -ENOBUFS;
	117	}
	118
	119	unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
	120	{
	121	struct dccp_sock *dp = dccp_sk(sk);
	122	int mss_now;
	123
	124	/*
7690af3f ACM	125	* FIXME: we really should be using the af_specific thing to support
	126	* IPv6.
	127	* mss_now = pmtu - tp->af_specific->net_header_len -
	128	* sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
7c657876	129	*/
7690af3f ACM	130	mss_now = pmtu - sizeof(struct iphdr) - sizeof(struct dccp_hdr) -
7690af3f ACM	131	sizeof(struct dccp_hdr_ext);
7c657876 ACM	132
	133	/* Now subtract optional transport overhead */
	134	mss_now -= dp->dccps_ext_header_len;
	135
	136	/*
	137	* FIXME: this should come from the CCID infrastructure, where, say,
	138	* TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
	139	* put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
	140	* TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
	141	* make it a multiple of 4
	142	*/
	143
	144	mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
	145
	146	/* And store cached results */
	147	dp->dccps_pmtu_cookie = pmtu;
	148	dp->dccps_mss_cache = mss_now;
	149
	150	return mss_now;
	151	}
	152
c530cfb1 ACM	153	void dccp_write_space(struct sock *sk)
	154	{
	155	read_lock(&sk->sk_callback_lock);
	156
	157	if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
	158	wake_up_interruptible(sk->sk_sleep);
	159	/* Should agree with poll, otherwise some programs break */
	160	if (sock_writeable(sk))
	161	sk_wake_async(sk, 2, POLL_OUT);
	162
	163	read_unlock(&sk->sk_callback_lock);
	164	}
	165
d6809c12 ACM	166	/**
	167	* dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
	168	* @sk: socket to wait for
	169	* @timeo: for how long
	170	*/
	171	static int dccp_wait_for_ccid(struct sock sk, struct sk_buff skb,
	172	long *timeo)
	173	{
	174	struct dccp_sock *dp = dccp_sk(sk);
	175	DEFINE_WAIT(wait);
	176	long delay;
	177	int rc;
	178
	179	while (1) {
	180	prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
	181
	182	if (sk->sk_err \|\| (sk->sk_shutdown & SEND_SHUTDOWN))
	183	goto do_error;
	184	if (!*timeo)
	185	goto do_nonblock;
	186	if (signal_pending(current))
	187	goto do_interrupted;
	188
	189	rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
	190	skb->len);
	191	if (rc <= 0)
	192	break;
	193	delay = msecs_to_jiffies(rc);
	194	if (delay > *timeo \|\| delay < 0)
	195	goto do_nonblock;
	196
	197	sk->sk_write_pending++;
	198	release_sock(sk);
	199	*timeo -= schedule_timeout(delay);
	200	lock_sock(sk);
	201	sk->sk_write_pending--;
	202	}
	203	out:
	204	finish_wait(sk->sk_sleep, &wait);
	205	return rc;
	206
	207	do_error:
	208	rc = -EPIPE;
	209	goto out;
	210	do_nonblock:
	211	rc = -EAGAIN;
	212	goto out;
	213	do_interrupted:
	214	rc = sock_intr_errno(*timeo);
	215	goto out;
	216	}
	217
	218	int dccp_write_xmit(struct sock sk, struct sk_buff skb, long *timeo)
27258ee5 ACM	219	{
27258ee5 ACM	220	const struct dccp_sock *dp = dccp_sk(sk);
d6809c12 ACM	221	int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
	222	skb->len);
	223
	224	if (err > 0)
	225	err = dccp_wait_for_ccid(sk, skb, timeo);
27258ee5 ACM	226
	227	if (err == 0) {
	228	const struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
	229	struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
d6809c12	230	const int len = skb->len;
27258ee5 ACM	231
	232	if (sk->sk_state == DCCP_PARTOPEN) {
	233	/* See 8.1.5. Handshake Completion */
	234	inet_csk_schedule_ack(sk);
	235	inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
	236	inet_csk(sk)->icsk_rto,
	237	DCCP_RTO_MAX);
	238	dcb->dccpd_type = DCCP_PKT_DATAACK;
	239	/*
	240	* FIXME: we really should have a
	241	* dccps_ack_pending or use icsk.
	242	*/
	243	} else if (inet_csk_ack_scheduled(sk) \|\|
a4beb1b6	244	dp->dccps_timestamp_echo != 0 \|\|
27258ee5 ACM	245	(dp->dccps_options.dccpo_send_ack_vector &&
	246	ap->dccpap_buf_ackno != DCCP_MAX_SEQNO + 1 &&
	247	ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1))
	248	dcb->dccpd_type = DCCP_PKT_DATAACK;
	249	else
	250	dcb->dccpd_type = DCCP_PKT_DATA;
	251
	252	err = dccp_transmit_skb(sk, skb);
	253	ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
	254	}
	255
	256	return err;
	257	}
	258
7c657876 ACM	259	int dccp_retransmit_skb(struct sock sk, struct sk_buff skb)
	260	{
	261	if (inet_sk_rebuild_header(sk) != 0)
	262	return -EHOSTUNREACH; /* Routing failure or similar. */
	263
	264	return dccp_transmit_skb(sk, (skb_cloned(skb) ?
	265	pskb_copy(skb, GFP_ATOMIC):
	266	skb_clone(skb, GFP_ATOMIC)));
	267	}
	268
	269	struct sk_buff dccp_make_response(struct sock sk, struct dst_entry *dst,
	270	struct request_sock *req)
	271	{
	272	struct dccp_hdr *dh;
	273	const int dccp_header_size = sizeof(struct dccp_hdr) +
	274	sizeof(struct dccp_hdr_ext) +
	275	sizeof(struct dccp_hdr_response);
	276	struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
	277	dccp_header_size, 1,
	278	GFP_ATOMIC);
	279	if (skb == NULL)
	280	return NULL;
	281
	282	/* Reserve space for headers. */
	283	skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
	284
	285	skb->dst = dst_clone(dst);
	286	skb->csum = 0;
	287
	288	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
	289	DCCP_SKB_CB(skb)->dccpd_seq = dccp_rsk(req)->dreq_iss;
	290	dccp_insert_options(sk, skb);
	291
	292	skb->h.raw = skb_push(skb, dccp_header_size);
	293
	294	dh = dccp_hdr(skb);
	295	memset(dh, 0, dccp_header_size);
	296
	297	dh->dccph_sport = inet_sk(sk)->sport;
	298	dh->dccph_dport = inet_rsk(req)->rmt_port;
7690af3f ACM	299	dh->dccph_doff = (dccp_header_size +
7690af3f ACM	300	DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
7c657876 ACM	301	dh->dccph_type = DCCP_PKT_RESPONSE;
	302	dh->dccph_x = 1;
	303	dccp_hdr_set_seq(dh, dccp_rsk(req)->dreq_iss);
	304	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dccp_rsk(req)->dreq_isr);
	305
95b81ef7 YN	306	dh->dccph_checksum = dccp_v4_checksum(skb, inet_rsk(req)->loc_addr,
95b81ef7 YN	307	inet_rsk(req)->rmt_addr);
7c657876 ACM	308
	309	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	310	return skb;
	311	}
	312
	313	struct sk_buff dccp_make_reset(struct sock sk, struct dst_entry *dst,
	314	const enum dccp_reset_codes code)
	315
	316	{
	317	struct dccp_hdr *dh;
	318	struct dccp_sock *dp = dccp_sk(sk);
	319	const int dccp_header_size = sizeof(struct dccp_hdr) +
	320	sizeof(struct dccp_hdr_ext) +
	321	sizeof(struct dccp_hdr_reset);
	322	struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
	323	dccp_header_size, 1,
	324	GFP_ATOMIC);
	325	if (skb == NULL)
	326	return NULL;
	327
	328	/* Reserve space for headers. */
	329	skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
	330
	331	skb->dst = dst_clone(dst);
	332	skb->csum = 0;
	333
	334	dccp_inc_seqno(&dp->dccps_gss);
	335
	336	DCCP_SKB_CB(skb)->dccpd_reset_code = code;
	337	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET;
	338	DCCP_SKB_CB(skb)->dccpd_seq = dp->dccps_gss;
	339	dccp_insert_options(sk, skb);
	340
	341	skb->h.raw = skb_push(skb, dccp_header_size);
	342
	343	dh = dccp_hdr(skb);
	344	memset(dh, 0, dccp_header_size);
	345
	346	dh->dccph_sport = inet_sk(sk)->sport;
	347	dh->dccph_dport = inet_sk(sk)->dport;
7690af3f ACM	348	dh->dccph_doff = (dccp_header_size +
7690af3f ACM	349	DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
7c657876 ACM	350	dh->dccph_type = DCCP_PKT_RESET;
	351	dh->dccph_x = 1;
	352	dccp_hdr_set_seq(dh, dp->dccps_gss);
	353	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
	354
	355	dccp_hdr_reset(skb)->dccph_reset_code = code;
	356
95b81ef7 YN	357	dh->dccph_checksum = dccp_v4_checksum(skb, inet_sk(sk)->saddr,
95b81ef7 YN	358	inet_sk(sk)->daddr);
7c657876 ACM	359
	360	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	361	return skb;
	362	}
	363
	364	/*
	365	* Do all connect socket setups that can be done AF independent.
	366	*/
	367	static inline void dccp_connect_init(struct sock *sk)
	368	{
	369	struct dst_entry *dst = __sk_dst_get(sk);
	370	struct inet_connection_sock *icsk = inet_csk(sk);
	371
	372	sk->sk_err = 0;
	373	sock_reset_flag(sk, SOCK_DONE);
	374
	375	dccp_sync_mss(sk, dst_mtu(dst));
	376
	377	/*
	378	* FIXME: set dp->{dccps_swh,dccps_swl}, with
	379	* something like dccp_inc_seq
	380	*/
	381
	382	icsk->icsk_retransmits = 0;
	383	}
	384
	385	int dccp_connect(struct sock *sk)
	386	{
	387	struct sk_buff *skb;
	388	struct inet_connection_sock *icsk = inet_csk(sk);
	389
	390	dccp_connect_init(sk);
	391
	392	skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation);
	393	if (unlikely(skb == NULL))
	394	return -ENOBUFS;
	395
	396	/* Reserve space for headers. */
	397	skb_reserve(skb, MAX_DCCP_HEADER);
	398
	399	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
	400	/* FIXME: set service to something meaningful, coming
	401	* from userspace*/
	402	DCCP_SKB_CB(skb)->dccpd_service = 0;
	403	skb->csum = 0;
	404	skb_set_owner_w(skb, sk);
	405
	406	BUG_TRAP(sk->sk_send_head == NULL);
	407	sk->sk_send_head = skb;
	408	dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
	409	DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
	410
	411	/* Timer for repeating the REQUEST until an answer. */
27258ee5 ACM	412	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
27258ee5 ACM	413	icsk->icsk_rto, DCCP_RTO_MAX);
7c657876 ACM	414	return 0;
	415	}
	416
	417	void dccp_send_ack(struct sock *sk)
	418	{
	419	/* If we have been reset, we may not send again. */
	420	if (sk->sk_state != DCCP_CLOSED) {
	421	struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
	422
	423	if (skb == NULL) {
	424	inet_csk_schedule_ack(sk);
	425	inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
7690af3f ACM	426	inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
	427	TCP_DELACK_MAX,
	428	DCCP_RTO_MAX);
7c657876 ACM	429	return;
	430	}
	431
	432	/* Reserve space for headers */
	433	skb_reserve(skb, MAX_DCCP_HEADER);
	434	skb->csum = 0;
	435	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
	436	skb_set_owner_w(skb, sk);
	437	dccp_transmit_skb(sk, skb);
	438	}
	439	}
	440
	441	EXPORT_SYMBOL_GPL(dccp_send_ack);
	442
	443	void dccp_send_delayed_ack(struct sock *sk)
	444	{
	445	struct inet_connection_sock *icsk = inet_csk(sk);
	446	/*
	447	* FIXME: tune this timer. elapsed time fixes the skew, so no problem
	448	* with using 2s, and active senders also piggyback the ACK into a
	449	* DATAACK packet, so this is really for quiescent senders.
	450	*/
	451	unsigned long timeout = jiffies + 2 * HZ;
	452
	453	/* Use new timeout only if there wasn't a older one earlier. */
	454	if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
	455	/* If delack timer was blocked or is about to expire,
	456	* send ACK now.
	457	*
	458	* FIXME: check the "about to expire" part
	459	*/
	460	if (icsk->icsk_ack.blocked) {
	461	dccp_send_ack(sk);
	462	return;
	463	}
	464
	465	if (!time_before(timeout, icsk->icsk_ack.timeout))
	466	timeout = icsk->icsk_ack.timeout;
	467	}
	468	icsk->icsk_ack.pending \|= ICSK_ACK_SCHED \| ICSK_ACK_TIMER;
	469	icsk->icsk_ack.timeout = timeout;
	470	sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
	471	}
	472
e92ae93a ACM	473	void dccp_send_sync(struct sock *sk, const u64 seq,
e92ae93a ACM	474	const enum dccp_pkt_type pkt_type)
7c657876 ACM	475	{
	476	/*
	477	* We are not putting this on the write queue, so
	478	* dccp_transmit_skb() will set the ownership to this
	479	* sock.
	480	*/
	481	struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
	482
	483	if (skb == NULL)
	484	/* FIXME: how to make sure the sync is sent? */
	485	return;
	486
	487	/* Reserve space for headers and prepare control bits. */
	488	skb_reserve(skb, MAX_DCCP_HEADER);
	489	skb->csum = 0;
e92ae93a	490	DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
7c657876 ACM	491	DCCP_SKB_CB(skb)->dccpd_seq = seq;
	492
	493	skb_set_owner_w(skb, sk);
	494	dccp_transmit_skb(sk, skb);
	495	}
	496
7690af3f ACM	497	/*
	498	* Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
	499	* cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
	500	* any circumstances.
7c657876	501	*/
7ad07e7c	502	void dccp_send_close(struct sock *sk, const int active)
7c657876 ACM	503	{
	504	struct dccp_sock *dp = dccp_sk(sk);
	505	struct sk_buff *skb;
7ad07e7c	506	const unsigned int prio = active ? GFP_KERNEL : GFP_ATOMIC;
7c657876	507
7ad07e7c ACM	508	skb = alloc_skb(sk->sk_prot->max_header, prio);
	509	if (skb == NULL)
	510	return;
7c657876 ACM	511
	512	/* Reserve space for headers and prepare control bits. */
	513	skb_reserve(skb, sk->sk_prot->max_header);
	514	skb->csum = 0;
7690af3f ACM	515	DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
7690af3f ACM	516	DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
7c657876 ACM	517
7c657876 ACM	518	skb_set_owner_w(skb, sk);
7ad07e7c ACM	519	if (active) {
	520	BUG_TRAP(sk->sk_send_head == NULL);
	521	sk->sk_send_head = skb;
	522	dccp_transmit_skb(sk, skb_clone(skb, prio));
	523	} else
	524	dccp_transmit_skb(sk, skb);
7c657876	525	}