[mirror_ubuntu-bionic-kernel.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);
		/*
		 * 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 =
							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);
	}

	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);
7690af3f ACM	65	/*
	66	* Data packets are not cloned as they are never retransmitted
	67	*/
7c657876 ACM	68	if (skb_cloned(skb))
	69	skb_set_owner_w(skb, sk);
	70
	71	/* Build DCCP header and checksum it. */
	72	memset(dh, 0, dccp_header_size);
	73	dh->dccph_type = dcb->dccpd_type;
	74	dh->dccph_sport = inet->sport;
	75	dh->dccph_dport = inet->dport;
	76	dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4;
	77	dh->dccph_ccval = dcb->dccpd_ccval;
	78	/* XXX For now we're using only 48 bits sequence numbers */
	79	dh->dccph_x = 1;
	80
	81	dp->dccps_awh = dp->dccps_gss;
	82	dccp_hdr_set_seq(dh, dp->dccps_gss);
	83	if (set_ack)
	84	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
	85
	86	switch (dcb->dccpd_type) {
	87	case DCCP_PKT_REQUEST:
7690af3f	88	dccp_hdr_request(skb)->dccph_req_service =
67e6b629	89	dp->dccps_service;
7c657876 ACM	90	break;
7c657876 ACM	91	case DCCP_PKT_RESET:
7690af3f ACM	92	dccp_hdr_reset(skb)->dccph_reset_code =
7690af3f ACM	93	dcb->dccpd_reset_code;
7c657876 ACM	94	break;
	95	}
	96
95b81ef7 YN	97	dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr,
95b81ef7 YN	98	inet->daddr);
7c657876	99
7ad07e7c	100	if (set_ack)
7c657876 ACM	101	dccp_event_ack_sent(sk);
	102
	103	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	104
	105	err = ip_queue_xmit(skb, 0);
	106	if (err <= 0)
	107	return err;
	108
	109	/* NET_XMIT_CN is special. It does not guarantee,
	110	* that this packet is lost. It tells that device
	111	* is about to start to drop packets or already
	112	* drops some packets of the same priority and
	113	* invokes us to send less aggressively.
	114	*/
	115	return err == NET_XMIT_CN ? 0 : err;
	116	}
	117	return -ENOBUFS;
	118	}
	119
	120	unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
	121	{
	122	struct dccp_sock *dp = dccp_sk(sk);
	123	int mss_now;
	124
	125	/*
7690af3f ACM	126	* FIXME: we really should be using the af_specific thing to support
	127	* IPv6.
	128	* mss_now = pmtu - tp->af_specific->net_header_len -
	129	* sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
7c657876	130	*/
7690af3f ACM	131	mss_now = pmtu - sizeof(struct iphdr) - sizeof(struct dccp_hdr) -
7690af3f ACM	132	sizeof(struct dccp_hdr_ext);
7c657876 ACM	133
	134	/* Now subtract optional transport overhead */
	135	mss_now -= dp->dccps_ext_header_len;
	136
	137	/*
	138	* FIXME: this should come from the CCID infrastructure, where, say,
	139	* TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
	140	* put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
	141	* TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
	142	* make it a multiple of 4
	143	*/
	144
	145	mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
	146
	147	/* And store cached results */
	148	dp->dccps_pmtu_cookie = pmtu;
	149	dp->dccps_mss_cache = mss_now;
	150
	151	return mss_now;
	152	}
	153
c530cfb1 ACM	154	void dccp_write_space(struct sock *sk)
	155	{
	156	read_lock(&sk->sk_callback_lock);
	157
	158	if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
	159	wake_up_interruptible(sk->sk_sleep);
	160	/* Should agree with poll, otherwise some programs break */
	161	if (sock_writeable(sk))
	162	sk_wake_async(sk, 2, POLL_OUT);
	163
	164	read_unlock(&sk->sk_callback_lock);
	165	}
	166
d6809c12 ACM	167	/**
	168	* dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet
	169	* @sk: socket to wait for
	170	* @timeo: for how long
	171	*/
	172	static int dccp_wait_for_ccid(struct sock sk, struct sk_buff skb,
	173	long *timeo)
	174	{
	175	struct dccp_sock *dp = dccp_sk(sk);
	176	DEFINE_WAIT(wait);
	177	long delay;
	178	int rc;
	179
	180	while (1) {
	181	prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
	182
	183	if (sk->sk_err \|\| (sk->sk_shutdown & SEND_SHUTDOWN))
	184	goto do_error;
	185	if (!*timeo)
	186	goto do_nonblock;
	187	if (signal_pending(current))
	188	goto do_interrupted;
	189
	190	rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
	191	skb->len);
	192	if (rc <= 0)
	193	break;
	194	delay = msecs_to_jiffies(rc);
	195	if (delay > *timeo \|\| delay < 0)
	196	goto do_nonblock;
	197
	198	sk->sk_write_pending++;
	199	release_sock(sk);
	200	*timeo -= schedule_timeout(delay);
	201	lock_sock(sk);
	202	sk->sk_write_pending--;
	203	}
	204	out:
	205	finish_wait(sk->sk_sleep, &wait);
	206	return rc;
	207
	208	do_error:
	209	rc = -EPIPE;
	210	goto out;
	211	do_nonblock:
	212	rc = -EAGAIN;
	213	goto out;
	214	do_interrupted:
	215	rc = sock_intr_errno(*timeo);
	216	goto out;
	217	}
	218
	219	int dccp_write_xmit(struct sock sk, struct sk_buff skb, long *timeo)
27258ee5 ACM	220	{
27258ee5 ACM	221	const struct dccp_sock *dp = dccp_sk(sk);
d6809c12 ACM	222	int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
	223	skb->len);
	224
	225	if (err > 0)
	226	err = dccp_wait_for_ccid(sk, skb, timeo);
27258ee5 ACM	227
27258ee5 ACM	228	if (err == 0) {
27258ee5	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;
ae31c339	239	} else if (dccp_ack_pending(sk))
27258ee5 ACM	240	dcb->dccpd_type = DCCP_PKT_DATAACK;
	241	else
	242	dcb->dccpd_type = DCCP_PKT_DATA;
	243
	244	err = dccp_transmit_skb(sk, skb);
	245	ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
	246	}
	247
	248	return err;
	249	}
	250
7c657876 ACM	251	int dccp_retransmit_skb(struct sock sk, struct sk_buff skb)
	252	{
	253	if (inet_sk_rebuild_header(sk) != 0)
	254	return -EHOSTUNREACH; /* Routing failure or similar. */
	255
	256	return dccp_transmit_skb(sk, (skb_cloned(skb) ?
	257	pskb_copy(skb, GFP_ATOMIC):
	258	skb_clone(skb, GFP_ATOMIC)));
	259	}
	260
	261	struct sk_buff dccp_make_response(struct sock sk, struct dst_entry *dst,
	262	struct request_sock *req)
	263	{
	264	struct dccp_hdr *dh;
67e6b629	265	struct dccp_request_sock *dreq;
7c657876 ACM	266	const int dccp_header_size = sizeof(struct dccp_hdr) +
	267	sizeof(struct dccp_hdr_ext) +
	268	sizeof(struct dccp_hdr_response);
	269	struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
	270	dccp_header_size, 1,
	271	GFP_ATOMIC);
	272	if (skb == NULL)
	273	return NULL;
	274
	275	/* Reserve space for headers. */
	276	skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
	277
	278	skb->dst = dst_clone(dst);
	279	skb->csum = 0;
	280
67e6b629	281	dreq = dccp_rsk(req);
7c657876	282	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
67e6b629	283	DCCP_SKB_CB(skb)->dccpd_seq = dreq->dreq_iss;
7c657876 ACM	284	dccp_insert_options(sk, skb);
	285
	286	skb->h.raw = skb_push(skb, dccp_header_size);
	287
	288	dh = dccp_hdr(skb);
	289	memset(dh, 0, dccp_header_size);
	290
	291	dh->dccph_sport = inet_sk(sk)->sport;
	292	dh->dccph_dport = inet_rsk(req)->rmt_port;
7690af3f ACM	293	dh->dccph_doff = (dccp_header_size +
7690af3f ACM	294	DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
7c657876 ACM	295	dh->dccph_type = DCCP_PKT_RESPONSE;
7c657876 ACM	296	dh->dccph_x = 1;
67e6b629 ACM	297	dccp_hdr_set_seq(dh, dreq->dreq_iss);
	298	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr);
	299	dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service;
7c657876	300
95b81ef7 YN	301	dh->dccph_checksum = dccp_v4_checksum(skb, inet_rsk(req)->loc_addr,
95b81ef7 YN	302	inet_rsk(req)->rmt_addr);
7c657876 ACM	303
	304	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	305	return skb;
	306	}
	307
	308	struct sk_buff dccp_make_reset(struct sock sk, struct dst_entry *dst,
	309	const enum dccp_reset_codes code)
	310
	311	{
	312	struct dccp_hdr *dh;
	313	struct dccp_sock *dp = dccp_sk(sk);
	314	const int dccp_header_size = sizeof(struct dccp_hdr) +
	315	sizeof(struct dccp_hdr_ext) +
	316	sizeof(struct dccp_hdr_reset);
	317	struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
	318	dccp_header_size, 1,
	319	GFP_ATOMIC);
	320	if (skb == NULL)
	321	return NULL;
	322
	323	/* Reserve space for headers. */
	324	skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
	325
	326	skb->dst = dst_clone(dst);
	327	skb->csum = 0;
	328
	329	dccp_inc_seqno(&dp->dccps_gss);
	330
	331	DCCP_SKB_CB(skb)->dccpd_reset_code = code;
	332	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET;
	333	DCCP_SKB_CB(skb)->dccpd_seq = dp->dccps_gss;
	334	dccp_insert_options(sk, skb);
	335
	336	skb->h.raw = skb_push(skb, dccp_header_size);
	337
	338	dh = dccp_hdr(skb);
	339	memset(dh, 0, dccp_header_size);
	340
	341	dh->dccph_sport = inet_sk(sk)->sport;
	342	dh->dccph_dport = inet_sk(sk)->dport;
7690af3f ACM	343	dh->dccph_doff = (dccp_header_size +
7690af3f ACM	344	DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
7c657876 ACM	345	dh->dccph_type = DCCP_PKT_RESET;
	346	dh->dccph_x = 1;
	347	dccp_hdr_set_seq(dh, dp->dccps_gss);
	348	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
	349
	350	dccp_hdr_reset(skb)->dccph_reset_code = code;
	351
95b81ef7 YN	352	dh->dccph_checksum = dccp_v4_checksum(skb, inet_sk(sk)->saddr,
95b81ef7 YN	353	inet_sk(sk)->daddr);
7c657876 ACM	354
	355	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	356	return skb;
	357	}
	358
	359	/*
	360	* Do all connect socket setups that can be done AF independent.
	361	*/
	362	static inline void dccp_connect_init(struct sock *sk)
	363	{
	364	struct dst_entry *dst = __sk_dst_get(sk);
	365	struct inet_connection_sock *icsk = inet_csk(sk);
	366
	367	sk->sk_err = 0;
	368	sock_reset_flag(sk, SOCK_DONE);
	369
	370	dccp_sync_mss(sk, dst_mtu(dst));
	371
	372	/*
	373	* FIXME: set dp->{dccps_swh,dccps_swl}, with
	374	* something like dccp_inc_seq
	375	*/
	376
	377	icsk->icsk_retransmits = 0;
	378	}
	379
	380	int dccp_connect(struct sock *sk)
	381	{
	382	struct sk_buff *skb;
	383	struct inet_connection_sock *icsk = inet_csk(sk);
	384
	385	dccp_connect_init(sk);
	386
	387	skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation);
	388	if (unlikely(skb == NULL))
	389	return -ENOBUFS;
	390
	391	/* Reserve space for headers. */
	392	skb_reserve(skb, MAX_DCCP_HEADER);
	393
	394	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
7c657876 ACM	395	skb->csum = 0;
	396	skb_set_owner_w(skb, sk);
	397
	398	BUG_TRAP(sk->sk_send_head == NULL);
	399	sk->sk_send_head = skb;
	400	dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
	401	DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
	402
	403	/* Timer for repeating the REQUEST until an answer. */
27258ee5 ACM	404	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
27258ee5 ACM	405	icsk->icsk_rto, DCCP_RTO_MAX);
7c657876 ACM	406	return 0;
	407	}
	408
	409	void dccp_send_ack(struct sock *sk)
	410	{
	411	/* If we have been reset, we may not send again. */
	412	if (sk->sk_state != DCCP_CLOSED) {
	413	struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
	414
	415	if (skb == NULL) {
	416	inet_csk_schedule_ack(sk);
	417	inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
7690af3f ACM	418	inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
	419	TCP_DELACK_MAX,
	420	DCCP_RTO_MAX);
7c657876 ACM	421	return;
	422	}
	423
	424	/* Reserve space for headers */
	425	skb_reserve(skb, MAX_DCCP_HEADER);
	426	skb->csum = 0;
	427	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
	428	skb_set_owner_w(skb, sk);
	429	dccp_transmit_skb(sk, skb);
	430	}
	431	}
	432
	433	EXPORT_SYMBOL_GPL(dccp_send_ack);
	434
	435	void dccp_send_delayed_ack(struct sock *sk)
	436	{
	437	struct inet_connection_sock *icsk = inet_csk(sk);
	438	/*
	439	* FIXME: tune this timer. elapsed time fixes the skew, so no problem
	440	* with using 2s, and active senders also piggyback the ACK into a
	441	* DATAACK packet, so this is really for quiescent senders.
	442	*/
	443	unsigned long timeout = jiffies + 2 * HZ;
	444
	445	/* Use new timeout only if there wasn't a older one earlier. */
	446	if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
	447	/* If delack timer was blocked or is about to expire,
	448	* send ACK now.
	449	*
	450	* FIXME: check the "about to expire" part
	451	*/
	452	if (icsk->icsk_ack.blocked) {
	453	dccp_send_ack(sk);
	454	return;
	455	}
	456
	457	if (!time_before(timeout, icsk->icsk_ack.timeout))
	458	timeout = icsk->icsk_ack.timeout;
	459	}
	460	icsk->icsk_ack.pending \|= ICSK_ACK_SCHED \| ICSK_ACK_TIMER;
	461	icsk->icsk_ack.timeout = timeout;
	462	sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
	463	}
	464
e92ae93a ACM	465	void dccp_send_sync(struct sock *sk, const u64 seq,
e92ae93a ACM	466	const enum dccp_pkt_type pkt_type)
7c657876 ACM	467	{
	468	/*
	469	* We are not putting this on the write queue, so
	470	* dccp_transmit_skb() will set the ownership to this
	471	* sock.
	472	*/
	473	struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
	474
	475	if (skb == NULL)
	476	/* FIXME: how to make sure the sync is sent? */
	477	return;
	478
	479	/* Reserve space for headers and prepare control bits. */
	480	skb_reserve(skb, MAX_DCCP_HEADER);
	481	skb->csum = 0;
e92ae93a	482	DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
7c657876 ACM	483	DCCP_SKB_CB(skb)->dccpd_seq = seq;
	484
	485	skb_set_owner_w(skb, sk);
	486	dccp_transmit_skb(sk, skb);
	487	}
	488
7690af3f ACM	489	/*
	490	* Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
	491	* cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
	492	* any circumstances.
7c657876	493	*/
7ad07e7c	494	void dccp_send_close(struct sock *sk, const int active)
7c657876 ACM	495	{
	496	struct dccp_sock *dp = dccp_sk(sk);
	497	struct sk_buff *skb;
7ad07e7c	498	const unsigned int prio = active ? GFP_KERNEL : GFP_ATOMIC;
7c657876	499
7ad07e7c ACM	500	skb = alloc_skb(sk->sk_prot->max_header, prio);
	501	if (skb == NULL)
	502	return;
7c657876 ACM	503
	504	/* Reserve space for headers and prepare control bits. */
	505	skb_reserve(skb, sk->sk_prot->max_header);
	506	skb->csum = 0;
7690af3f ACM	507	DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ?
7690af3f ACM	508	DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
7c657876 ACM	509
7c657876 ACM	510	skb_set_owner_w(skb, sk);
7ad07e7c ACM	511	if (active) {
	512	BUG_TRAP(sk->sk_send_head == NULL);
	513	sk->sk_send_head = skb;
	514	dccp_transmit_skb(sk, skb_clone(skb, prio));
	515	} else
	516	dccp_transmit_skb(sk, skb);
7c657876	517	}