summaryrefslogtreecommitdiffstats
path: root/net/dccp/output.c
blob: 4945eaa9d1a4206a6917cd3fcf7380bb76b384a0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
/*
 *  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);
}
OpenPOWER on IntegriCloud