[deliverable/linux.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 "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;

		/*
		 * FIXME: study DCCP_PKT_SYNC[ACK] to see what is the right thing 
		 * to do here...
		 */
		dccp_inc_seqno(&dp->dccps_gss);

		dcb->dccpd_seq = dp->dccps_gss;
		dccp_insert_options(sk, skb);

		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;
		}
		
		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 (dcb->dccpd_type == DCCP_PKT_ACK ||
		    dcb->dccpd_type == DCCP_PKT_DATAACK)
			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;
}

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, TCP_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, TCP_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, u64 seq)
{
	/*
	 * 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 = DCCP_PKT_SYNC;
	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)
{
	struct dccp_sock *dp = dccp_sk(sk);
	struct sk_buff *skb;

	/* Socket is locked, keep trying until memory is available. */
	for (;;) {
		skb = alloc_skb(sk->sk_prot->max_header, GFP_KERNEL);
		if (skb != NULL)
			break;
		yield();
	}

	/* 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);
	dccp_transmit_skb(sk, skb);

	ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
	ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
}
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
	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) +
	43	dccp_packet_hdr_len(dcb->dccpd_type);
	44	int err, set_ack = 1;
	45	u64 ackno = dp->dccps_gsr;
	46
	47	/*
	48	* FIXME: study DCCP_PKT_SYNC[ACK] to see what is the right thing
	49	* to do here...
	50	*/
	51	dccp_inc_seqno(&dp->dccps_gss);
	52
	53	dcb->dccpd_seq = dp->dccps_gss;
	54	dccp_insert_options(sk, skb);
	55
	56	switch (dcb->dccpd_type) {
	57	case DCCP_PKT_DATA:
	58	set_ack = 0;
	59	break;
	60	case DCCP_PKT_SYNC:
	61	case DCCP_PKT_SYNCACK:
	62	ackno = dcb->dccpd_seq;
	63	break;
	64	}
65
66	skb->h.raw = skb_push(skb, dccp_header_size);
67	dh = dccp_hdr(skb);
68	/* Data packets are not cloned as they are never retransmitted */
69	if (skb_cloned(skb))
70	skb_set_owner_w(skb, sk);
71
72	/* Build DCCP header and checksum it. */
73	memset(dh, 0, dccp_header_size);
74	dh->dccph_type = dcb->dccpd_type;
75	dh->dccph_sport = inet->sport;
76	dh->dccph_dport = inet->dport;
77	dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4;
78	dh->dccph_ccval = dcb->dccpd_ccval;
79	/* XXX For now we're using only 48 bits sequence numbers */
80	dh->dccph_x = 1;
81
82	dp->dccps_awh = dp->dccps_gss;
83	dccp_hdr_set_seq(dh, dp->dccps_gss);
84	if (set_ack)
85	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
86
87	switch (dcb->dccpd_type) {
88	case DCCP_PKT_REQUEST:
89	dccp_hdr_request(skb)->dccph_req_service = dcb->dccpd_service;
90	break;
91	case DCCP_PKT_RESET:
92	dccp_hdr_reset(skb)->dccph_reset_code = dcb->dccpd_reset_code;
93	break;
94	}
95
95b81ef7 YN	96	dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr,
95b81ef7 YN	97	inet->daddr);
7c657876 ACM	98
	99	if (dcb->dccpd_type == DCCP_PKT_ACK \|\|
	100	dcb->dccpd_type == DCCP_PKT_DATAACK)
	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	/*
	126	* FIXME: we really should be using the af_specific thing to support IPv6.
	127	* mss_now = pmtu - tp->af_specific->net_header_len - sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
	128	*/
	129	mss_now = pmtu - sizeof(struct iphdr) - sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
	130
	131	/* Now subtract optional transport overhead */
	132	mss_now -= dp->dccps_ext_header_len;
	133
	134	/*
	135	* FIXME: this should come from the CCID infrastructure, where, say,
	136	* TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
	137	* put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
	138	* TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
	139	* make it a multiple of 4
	140	*/
	141
	142	mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
	143
	144	/* And store cached results */
	145	dp->dccps_pmtu_cookie = pmtu;
	146	dp->dccps_mss_cache = mss_now;
	147
	148	return mss_now;
	149	}
	150
	151	int dccp_retransmit_skb(struct sock sk, struct sk_buff skb)
	152	{
	153	if (inet_sk_rebuild_header(sk) != 0)
	154	return -EHOSTUNREACH; /* Routing failure or similar. */
	155
	156	return dccp_transmit_skb(sk, (skb_cloned(skb) ?
	157	pskb_copy(skb, GFP_ATOMIC):
	158	skb_clone(skb, GFP_ATOMIC)));
	159	}
	160
	161	struct sk_buff dccp_make_response(struct sock sk, struct dst_entry *dst,
162	struct request_sock *req)
163	{
164	struct dccp_hdr *dh;
165	const int dccp_header_size = sizeof(struct dccp_hdr) +
166	sizeof(struct dccp_hdr_ext) +
167	sizeof(struct dccp_hdr_response);
168	struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
169	dccp_header_size, 1,
170	GFP_ATOMIC);
171	if (skb == NULL)
172	return NULL;
173
174	/* Reserve space for headers. */
175	skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
176
177	skb->dst = dst_clone(dst);
178	skb->csum = 0;
179
180	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
181	DCCP_SKB_CB(skb)->dccpd_seq = dccp_rsk(req)->dreq_iss;
182	dccp_insert_options(sk, skb);
183
184	skb->h.raw = skb_push(skb, dccp_header_size);
185
186	dh = dccp_hdr(skb);
187	memset(dh, 0, dccp_header_size);
188
189	dh->dccph_sport = inet_sk(sk)->sport;
190	dh->dccph_dport = inet_rsk(req)->rmt_port;
191	dh->dccph_doff = (dccp_header_size + DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
192	dh->dccph_type = DCCP_PKT_RESPONSE;
193	dh->dccph_x = 1;
194	dccp_hdr_set_seq(dh, dccp_rsk(req)->dreq_iss);
195	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dccp_rsk(req)->dreq_isr);
196
95b81ef7 YN	197	dh->dccph_checksum = dccp_v4_checksum(skb, inet_rsk(req)->loc_addr,
95b81ef7 YN	198	inet_rsk(req)->rmt_addr);
7c657876 ACM	199
	200	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	201	return skb;
	202	}
	203
	204	struct sk_buff dccp_make_reset(struct sock sk, struct dst_entry *dst,
	205	const enum dccp_reset_codes code)
	206
	207	{
	208	struct dccp_hdr *dh;
	209	struct dccp_sock *dp = dccp_sk(sk);
	210	const int dccp_header_size = sizeof(struct dccp_hdr) +
	211	sizeof(struct dccp_hdr_ext) +
	212	sizeof(struct dccp_hdr_reset);
	213	struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
	214	dccp_header_size, 1,
	215	GFP_ATOMIC);
	216	if (skb == NULL)
	217	return NULL;
	218
	219	/* Reserve space for headers. */
	220	skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
	221
	222	skb->dst = dst_clone(dst);
	223	skb->csum = 0;
	224
	225	dccp_inc_seqno(&dp->dccps_gss);
	226
	227	DCCP_SKB_CB(skb)->dccpd_reset_code = code;
	228	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET;
	229	DCCP_SKB_CB(skb)->dccpd_seq = dp->dccps_gss;
	230	dccp_insert_options(sk, skb);
	231
	232	skb->h.raw = skb_push(skb, dccp_header_size);
	233
	234	dh = dccp_hdr(skb);
	235	memset(dh, 0, dccp_header_size);
	236
	237	dh->dccph_sport = inet_sk(sk)->sport;
	238	dh->dccph_dport = inet_sk(sk)->dport;
	239	dh->dccph_doff = (dccp_header_size + DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
	240	dh->dccph_type = DCCP_PKT_RESET;
	241	dh->dccph_x = 1;
	242	dccp_hdr_set_seq(dh, dp->dccps_gss);
	243	dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
	244
	245	dccp_hdr_reset(skb)->dccph_reset_code = code;
	246
95b81ef7 YN	247	dh->dccph_checksum = dccp_v4_checksum(skb, inet_sk(sk)->saddr,
95b81ef7 YN	248	inet_sk(sk)->daddr);
7c657876 ACM	249
	250	DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
	251	return skb;
	252	}
	253
	254	/*
	255	* Do all connect socket setups that can be done AF independent.
	256	*/
	257	static inline void dccp_connect_init(struct sock *sk)
	258	{
	259	struct dst_entry *dst = __sk_dst_get(sk);
	260	struct inet_connection_sock *icsk = inet_csk(sk);
	261
	262	sk->sk_err = 0;
	263	sock_reset_flag(sk, SOCK_DONE);
	264
	265	dccp_sync_mss(sk, dst_mtu(dst));
	266
	267	/*
	268	* FIXME: set dp->{dccps_swh,dccps_swl}, with
	269	* something like dccp_inc_seq
	270	*/
	271
	272	icsk->icsk_retransmits = 0;
	273	}
	274
	275	int dccp_connect(struct sock *sk)
	276	{
	277	struct sk_buff *skb;
	278	struct inet_connection_sock *icsk = inet_csk(sk);
	279
	280	dccp_connect_init(sk);
	281
	282	skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation);
	283	if (unlikely(skb == NULL))
	284	return -ENOBUFS;
	285
	286	/* Reserve space for headers. */
	287	skb_reserve(skb, MAX_DCCP_HEADER);
	288
	289	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
	290	/* FIXME: set service to something meaningful, coming
	291	* from userspace*/
	292	DCCP_SKB_CB(skb)->dccpd_service = 0;
	293	skb->csum = 0;
	294	skb_set_owner_w(skb, sk);
	295
	296	BUG_TRAP(sk->sk_send_head == NULL);
	297	sk->sk_send_head = skb;
	298	dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
	299	DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
	300
	301	/* Timer for repeating the REQUEST until an answer. */
	302	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX);
	303	return 0;
	304	}
	305
	306	void dccp_send_ack(struct sock *sk)
	307	{
	308	/* If we have been reset, we may not send again. */
	309	if (sk->sk_state != DCCP_CLOSED) {
	310	struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
	311
	312	if (skb == NULL) {
313	inet_csk_schedule_ack(sk);
314	inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
315	inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, TCP_DELACK_MAX, TCP_RTO_MAX);
316	return;
317	}
318
319	/* Reserve space for headers */
320	skb_reserve(skb, MAX_DCCP_HEADER);
321	skb->csum = 0;
322	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
323	skb_set_owner_w(skb, sk);
324	dccp_transmit_skb(sk, skb);
325	}
326	}
327
328	EXPORT_SYMBOL_GPL(dccp_send_ack);
329
330	void dccp_send_delayed_ack(struct sock *sk)
331	{
332	struct inet_connection_sock *icsk = inet_csk(sk);
333	/*
334	* FIXME: tune this timer. elapsed time fixes the skew, so no problem
335	* with using 2s, and active senders also piggyback the ACK into a
336	* DATAACK packet, so this is really for quiescent senders.
337	*/
338	unsigned long timeout = jiffies + 2 * HZ;
339
340	/* Use new timeout only if there wasn't a older one earlier. */
341	if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
342	/* If delack timer was blocked or is about to expire,
343	* send ACK now.
344	*
345	* FIXME: check the "about to expire" part
346	*/
347	if (icsk->icsk_ack.blocked) {
348	dccp_send_ack(sk);
349	return;
350	}
351
352	if (!time_before(timeout, icsk->icsk_ack.timeout))
353	timeout = icsk->icsk_ack.timeout;
354	}
355	icsk->icsk_ack.pending \|= ICSK_ACK_SCHED \| ICSK_ACK_TIMER;
356	icsk->icsk_ack.timeout = timeout;
357	sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
358	}
359
360	void dccp_send_sync(struct sock *sk, u64 seq)
361	{
362	/*
363	* We are not putting this on the write queue, so
364	* dccp_transmit_skb() will set the ownership to this
365	* sock.
366	*/
367	struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
368
369	if (skb == NULL)
370	/* FIXME: how to make sure the sync is sent? */
371	return;
372
373	/* Reserve space for headers and prepare control bits. */
374	skb_reserve(skb, MAX_DCCP_HEADER);
375	skb->csum = 0;
376	DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_SYNC;
377	DCCP_SKB_CB(skb)->dccpd_seq = seq;
378
379	skb_set_owner_w(skb, sk);
380	dccp_transmit_skb(sk, skb);
381	}
382
383	/* Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This cannot be
384	* allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under any circumstances.
385	*/
386	void dccp_send_close(struct sock *sk)
387	{
388	struct dccp_sock *dp = dccp_sk(sk);
389	struct sk_buff *skb;
390
391	/* Socket is locked, keep trying until memory is available. */
392	for (;;) {
393	skb = alloc_skb(sk->sk_prot->max_header, GFP_KERNEL);
394	if (skb != NULL)
395	break;
396	yield();
397	}
398
399	/* Reserve space for headers and prepare control bits. */
400	skb_reserve(skb, sk->sk_prot->max_header);
401	skb->csum = 0;
402	DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ? DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
403
404	skb_set_owner_w(skb, sk);
405	dccp_transmit_skb(sk, skb);
406
407	ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
408	ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
409	}