Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
3 | * operating system. INET is implemented using the BSD Socket | |
4 | * interface as the means of communication with the user level. | |
5 | * | |
6 | * Implementation of the Transmission Control Protocol(TCP). | |
7 | * | |
8 | * Version: $Id: tcp_output.c,v 1.146 2002/02/01 22:01:04 davem Exp $ | |
9 | * | |
02c30a84 | 10 | * Authors: Ross Biro |
1da177e4 LT |
11 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
12 | * Mark Evans, <evansmp@uhura.aston.ac.uk> | |
13 | * Corey Minyard <wf-rch!minyard@relay.EU.net> | |
14 | * Florian La Roche, <flla@stud.uni-sb.de> | |
15 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> | |
16 | * Linus Torvalds, <torvalds@cs.helsinki.fi> | |
17 | * Alan Cox, <gw4pts@gw4pts.ampr.org> | |
18 | * Matthew Dillon, <dillon@apollo.west.oic.com> | |
19 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> | |
20 | * Jorge Cwik, <jorge@laser.satlink.net> | |
21 | */ | |
22 | ||
23 | /* | |
24 | * Changes: Pedro Roque : Retransmit queue handled by TCP. | |
25 | * : Fragmentation on mtu decrease | |
26 | * : Segment collapse on retransmit | |
27 | * : AF independence | |
28 | * | |
29 | * Linus Torvalds : send_delayed_ack | |
30 | * David S. Miller : Charge memory using the right skb | |
31 | * during syn/ack processing. | |
32 | * David S. Miller : Output engine completely rewritten. | |
33 | * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. | |
34 | * Cacophonix Gaul : draft-minshall-nagle-01 | |
35 | * J Hadi Salim : ECN support | |
36 | * | |
37 | */ | |
38 | ||
39 | #include <net/tcp.h> | |
40 | ||
41 | #include <linux/compiler.h> | |
42 | #include <linux/module.h> | |
43 | #include <linux/smp_lock.h> | |
44 | ||
45 | /* People can turn this off for buggy TCP's found in printers etc. */ | |
46 | int sysctl_tcp_retrans_collapse = 1; | |
47 | ||
48 | /* This limits the percentage of the congestion window which we | |
49 | * will allow a single TSO frame to consume. Building TSO frames | |
50 | * which are too large can cause TCP streams to be bursty. | |
51 | */ | |
c1b4a7e6 | 52 | int sysctl_tcp_tso_win_divisor = 3; |
1da177e4 | 53 | |
40efc6fa SH |
54 | static void update_send_head(struct sock *sk, struct tcp_sock *tp, |
55 | struct sk_buff *skb) | |
1da177e4 LT |
56 | { |
57 | sk->sk_send_head = skb->next; | |
58 | if (sk->sk_send_head == (struct sk_buff *)&sk->sk_write_queue) | |
59 | sk->sk_send_head = NULL; | |
60 | tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; | |
61 | tcp_packets_out_inc(sk, tp, skb); | |
62 | } | |
63 | ||
64 | /* SND.NXT, if window was not shrunk. | |
65 | * If window has been shrunk, what should we make? It is not clear at all. | |
66 | * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( | |
67 | * Anything in between SND.UNA...SND.UNA+SND.WND also can be already | |
68 | * invalid. OK, let's make this for now: | |
69 | */ | |
70 | static inline __u32 tcp_acceptable_seq(struct sock *sk, struct tcp_sock *tp) | |
71 | { | |
72 | if (!before(tp->snd_una+tp->snd_wnd, tp->snd_nxt)) | |
73 | return tp->snd_nxt; | |
74 | else | |
75 | return tp->snd_una+tp->snd_wnd; | |
76 | } | |
77 | ||
78 | /* Calculate mss to advertise in SYN segment. | |
79 | * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: | |
80 | * | |
81 | * 1. It is independent of path mtu. | |
82 | * 2. Ideally, it is maximal possible segment size i.e. 65535-40. | |
83 | * 3. For IPv4 it is reasonable to calculate it from maximal MTU of | |
84 | * attached devices, because some buggy hosts are confused by | |
85 | * large MSS. | |
86 | * 4. We do not make 3, we advertise MSS, calculated from first | |
87 | * hop device mtu, but allow to raise it to ip_rt_min_advmss. | |
88 | * This may be overridden via information stored in routing table. | |
89 | * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, | |
90 | * probably even Jumbo". | |
91 | */ | |
92 | static __u16 tcp_advertise_mss(struct sock *sk) | |
93 | { | |
94 | struct tcp_sock *tp = tcp_sk(sk); | |
95 | struct dst_entry *dst = __sk_dst_get(sk); | |
96 | int mss = tp->advmss; | |
97 | ||
98 | if (dst && dst_metric(dst, RTAX_ADVMSS) < mss) { | |
99 | mss = dst_metric(dst, RTAX_ADVMSS); | |
100 | tp->advmss = mss; | |
101 | } | |
102 | ||
103 | return (__u16)mss; | |
104 | } | |
105 | ||
106 | /* RFC2861. Reset CWND after idle period longer RTO to "restart window". | |
107 | * This is the first part of cwnd validation mechanism. */ | |
463c84b9 | 108 | static void tcp_cwnd_restart(struct sock *sk, struct dst_entry *dst) |
1da177e4 | 109 | { |
463c84b9 | 110 | struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
111 | s32 delta = tcp_time_stamp - tp->lsndtime; |
112 | u32 restart_cwnd = tcp_init_cwnd(tp, dst); | |
113 | u32 cwnd = tp->snd_cwnd; | |
114 | ||
6687e988 | 115 | tcp_ca_event(sk, CA_EVENT_CWND_RESTART); |
1da177e4 | 116 | |
6687e988 | 117 | tp->snd_ssthresh = tcp_current_ssthresh(sk); |
1da177e4 LT |
118 | restart_cwnd = min(restart_cwnd, cwnd); |
119 | ||
463c84b9 | 120 | while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) |
1da177e4 LT |
121 | cwnd >>= 1; |
122 | tp->snd_cwnd = max(cwnd, restart_cwnd); | |
123 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
124 | tp->snd_cwnd_used = 0; | |
125 | } | |
126 | ||
40efc6fa SH |
127 | static void tcp_event_data_sent(struct tcp_sock *tp, |
128 | struct sk_buff *skb, struct sock *sk) | |
1da177e4 | 129 | { |
463c84b9 ACM |
130 | struct inet_connection_sock *icsk = inet_csk(sk); |
131 | const u32 now = tcp_time_stamp; | |
1da177e4 | 132 | |
463c84b9 ACM |
133 | if (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto) |
134 | tcp_cwnd_restart(sk, __sk_dst_get(sk)); | |
1da177e4 LT |
135 | |
136 | tp->lsndtime = now; | |
137 | ||
138 | /* If it is a reply for ato after last received | |
139 | * packet, enter pingpong mode. | |
140 | */ | |
463c84b9 ACM |
141 | if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) |
142 | icsk->icsk_ack.pingpong = 1; | |
1da177e4 LT |
143 | } |
144 | ||
40efc6fa | 145 | static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) |
1da177e4 | 146 | { |
463c84b9 ACM |
147 | tcp_dec_quickack_mode(sk, pkts); |
148 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); | |
1da177e4 LT |
149 | } |
150 | ||
151 | /* Determine a window scaling and initial window to offer. | |
152 | * Based on the assumption that the given amount of space | |
153 | * will be offered. Store the results in the tp structure. | |
154 | * NOTE: for smooth operation initial space offering should | |
155 | * be a multiple of mss if possible. We assume here that mss >= 1. | |
156 | * This MUST be enforced by all callers. | |
157 | */ | |
158 | void tcp_select_initial_window(int __space, __u32 mss, | |
159 | __u32 *rcv_wnd, __u32 *window_clamp, | |
160 | int wscale_ok, __u8 *rcv_wscale) | |
161 | { | |
162 | unsigned int space = (__space < 0 ? 0 : __space); | |
163 | ||
164 | /* If no clamp set the clamp to the max possible scaled window */ | |
165 | if (*window_clamp == 0) | |
166 | (*window_clamp) = (65535 << 14); | |
167 | space = min(*window_clamp, space); | |
168 | ||
169 | /* Quantize space offering to a multiple of mss if possible. */ | |
170 | if (space > mss) | |
171 | space = (space / mss) * mss; | |
172 | ||
173 | /* NOTE: offering an initial window larger than 32767 | |
174 | * will break some buggy TCP stacks. We try to be nice. | |
175 | * If we are not window scaling, then this truncates | |
176 | * our initial window offering to 32k. There should also | |
177 | * be a sysctl option to stop being nice. | |
178 | */ | |
179 | (*rcv_wnd) = min(space, MAX_TCP_WINDOW); | |
180 | (*rcv_wscale) = 0; | |
181 | if (wscale_ok) { | |
182 | /* Set window scaling on max possible window | |
183 | * See RFC1323 for an explanation of the limit to 14 | |
184 | */ | |
185 | space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); | |
186 | while (space > 65535 && (*rcv_wscale) < 14) { | |
187 | space >>= 1; | |
188 | (*rcv_wscale)++; | |
189 | } | |
190 | } | |
191 | ||
192 | /* Set initial window to value enough for senders, | |
6b251858 | 193 | * following RFC2414. Senders, not following this RFC, |
1da177e4 LT |
194 | * will be satisfied with 2. |
195 | */ | |
196 | if (mss > (1<<*rcv_wscale)) { | |
01ff367e DM |
197 | int init_cwnd = 4; |
198 | if (mss > 1460*3) | |
1da177e4 | 199 | init_cwnd = 2; |
01ff367e DM |
200 | else if (mss > 1460) |
201 | init_cwnd = 3; | |
1da177e4 LT |
202 | if (*rcv_wnd > init_cwnd*mss) |
203 | *rcv_wnd = init_cwnd*mss; | |
204 | } | |
205 | ||
206 | /* Set the clamp no higher than max representable value */ | |
207 | (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); | |
208 | } | |
209 | ||
210 | /* Chose a new window to advertise, update state in tcp_sock for the | |
211 | * socket, and return result with RFC1323 scaling applied. The return | |
212 | * value can be stuffed directly into th->window for an outgoing | |
213 | * frame. | |
214 | */ | |
40efc6fa | 215 | static u16 tcp_select_window(struct sock *sk) |
1da177e4 LT |
216 | { |
217 | struct tcp_sock *tp = tcp_sk(sk); | |
218 | u32 cur_win = tcp_receive_window(tp); | |
219 | u32 new_win = __tcp_select_window(sk); | |
220 | ||
221 | /* Never shrink the offered window */ | |
222 | if(new_win < cur_win) { | |
223 | /* Danger Will Robinson! | |
224 | * Don't update rcv_wup/rcv_wnd here or else | |
225 | * we will not be able to advertise a zero | |
226 | * window in time. --DaveM | |
227 | * | |
228 | * Relax Will Robinson. | |
229 | */ | |
230 | new_win = cur_win; | |
231 | } | |
232 | tp->rcv_wnd = new_win; | |
233 | tp->rcv_wup = tp->rcv_nxt; | |
234 | ||
235 | /* Make sure we do not exceed the maximum possible | |
236 | * scaled window. | |
237 | */ | |
238 | if (!tp->rx_opt.rcv_wscale) | |
239 | new_win = min(new_win, MAX_TCP_WINDOW); | |
240 | else | |
241 | new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); | |
242 | ||
243 | /* RFC1323 scaling applied */ | |
244 | new_win >>= tp->rx_opt.rcv_wscale; | |
245 | ||
246 | /* If we advertise zero window, disable fast path. */ | |
247 | if (new_win == 0) | |
248 | tp->pred_flags = 0; | |
249 | ||
250 | return new_win; | |
251 | } | |
252 | ||
40efc6fa SH |
253 | static void tcp_build_and_update_options(__u32 *ptr, struct tcp_sock *tp, |
254 | __u32 tstamp) | |
255 | { | |
256 | if (tp->rx_opt.tstamp_ok) { | |
257 | *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | | |
258 | (TCPOPT_NOP << 16) | | |
259 | (TCPOPT_TIMESTAMP << 8) | | |
260 | TCPOLEN_TIMESTAMP); | |
261 | *ptr++ = htonl(tstamp); | |
262 | *ptr++ = htonl(tp->rx_opt.ts_recent); | |
263 | } | |
264 | if (tp->rx_opt.eff_sacks) { | |
265 | struct tcp_sack_block *sp = tp->rx_opt.dsack ? tp->duplicate_sack : tp->selective_acks; | |
266 | int this_sack; | |
267 | ||
268 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
269 | (TCPOPT_NOP << 16) | | |
270 | (TCPOPT_SACK << 8) | | |
271 | (TCPOLEN_SACK_BASE + (tp->rx_opt.eff_sacks * | |
272 | TCPOLEN_SACK_PERBLOCK))); | |
273 | for(this_sack = 0; this_sack < tp->rx_opt.eff_sacks; this_sack++) { | |
274 | *ptr++ = htonl(sp[this_sack].start_seq); | |
275 | *ptr++ = htonl(sp[this_sack].end_seq); | |
276 | } | |
277 | if (tp->rx_opt.dsack) { | |
278 | tp->rx_opt.dsack = 0; | |
279 | tp->rx_opt.eff_sacks--; | |
280 | } | |
281 | } | |
282 | } | |
283 | ||
284 | /* Construct a tcp options header for a SYN or SYN_ACK packet. | |
285 | * If this is every changed make sure to change the definition of | |
286 | * MAX_SYN_SIZE to match the new maximum number of options that you | |
287 | * can generate. | |
288 | */ | |
289 | static void tcp_syn_build_options(__u32 *ptr, int mss, int ts, int sack, | |
290 | int offer_wscale, int wscale, __u32 tstamp, | |
291 | __u32 ts_recent) | |
292 | { | |
293 | /* We always get an MSS option. | |
294 | * The option bytes which will be seen in normal data | |
295 | * packets should timestamps be used, must be in the MSS | |
296 | * advertised. But we subtract them from tp->mss_cache so | |
297 | * that calculations in tcp_sendmsg are simpler etc. | |
298 | * So account for this fact here if necessary. If we | |
299 | * don't do this correctly, as a receiver we won't | |
300 | * recognize data packets as being full sized when we | |
301 | * should, and thus we won't abide by the delayed ACK | |
302 | * rules correctly. | |
303 | * SACKs don't matter, we never delay an ACK when we | |
304 | * have any of those going out. | |
305 | */ | |
306 | *ptr++ = htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | mss); | |
307 | if (ts) { | |
308 | if(sack) | |
309 | *ptr++ = __constant_htonl((TCPOPT_SACK_PERM << 24) | (TCPOLEN_SACK_PERM << 16) | | |
310 | (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP); | |
311 | else | |
312 | *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | | |
313 | (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP); | |
314 | *ptr++ = htonl(tstamp); /* TSVAL */ | |
315 | *ptr++ = htonl(ts_recent); /* TSECR */ | |
316 | } else if(sack) | |
317 | *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | | |
318 | (TCPOPT_SACK_PERM << 8) | TCPOLEN_SACK_PERM); | |
319 | if (offer_wscale) | |
320 | *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_WINDOW << 16) | (TCPOLEN_WINDOW << 8) | (wscale)); | |
321 | } | |
1da177e4 LT |
322 | |
323 | /* This routine actually transmits TCP packets queued in by | |
324 | * tcp_do_sendmsg(). This is used by both the initial | |
325 | * transmission and possible later retransmissions. | |
326 | * All SKB's seen here are completely headerless. It is our | |
327 | * job to build the TCP header, and pass the packet down to | |
328 | * IP so it can do the same plus pass the packet off to the | |
329 | * device. | |
330 | * | |
331 | * We are working here with either a clone of the original | |
332 | * SKB, or a fresh unique copy made by the retransmit engine. | |
333 | */ | |
dfb4b9dc | 334 | static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, gfp_t gfp_mask) |
1da177e4 | 335 | { |
dfb4b9dc DM |
336 | const struct inet_connection_sock *icsk = inet_csk(sk); |
337 | struct inet_sock *inet; | |
338 | struct tcp_sock *tp; | |
339 | struct tcp_skb_cb *tcb; | |
340 | int tcp_header_size; | |
341 | struct tcphdr *th; | |
342 | int sysctl_flags; | |
343 | int err; | |
344 | ||
345 | BUG_ON(!skb || !tcp_skb_pcount(skb)); | |
346 | ||
347 | /* If congestion control is doing timestamping, we must | |
348 | * take such a timestamp before we potentially clone/copy. | |
349 | */ | |
350 | if (icsk->icsk_ca_ops->rtt_sample) | |
351 | __net_timestamp(skb); | |
352 | ||
353 | if (likely(clone_it)) { | |
354 | if (unlikely(skb_cloned(skb))) | |
355 | skb = pskb_copy(skb, gfp_mask); | |
356 | else | |
357 | skb = skb_clone(skb, gfp_mask); | |
358 | if (unlikely(!skb)) | |
359 | return -ENOBUFS; | |
360 | } | |
1da177e4 | 361 | |
dfb4b9dc DM |
362 | inet = inet_sk(sk); |
363 | tp = tcp_sk(sk); | |
364 | tcb = TCP_SKB_CB(skb); | |
365 | tcp_header_size = tp->tcp_header_len; | |
1da177e4 LT |
366 | |
367 | #define SYSCTL_FLAG_TSTAMPS 0x1 | |
368 | #define SYSCTL_FLAG_WSCALE 0x2 | |
369 | #define SYSCTL_FLAG_SACK 0x4 | |
370 | ||
dfb4b9dc DM |
371 | sysctl_flags = 0; |
372 | if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) { | |
373 | tcp_header_size = sizeof(struct tcphdr) + TCPOLEN_MSS; | |
374 | if(sysctl_tcp_timestamps) { | |
375 | tcp_header_size += TCPOLEN_TSTAMP_ALIGNED; | |
376 | sysctl_flags |= SYSCTL_FLAG_TSTAMPS; | |
1da177e4 | 377 | } |
dfb4b9dc DM |
378 | if (sysctl_tcp_window_scaling) { |
379 | tcp_header_size += TCPOLEN_WSCALE_ALIGNED; | |
380 | sysctl_flags |= SYSCTL_FLAG_WSCALE; | |
1da177e4 | 381 | } |
dfb4b9dc DM |
382 | if (sysctl_tcp_sack) { |
383 | sysctl_flags |= SYSCTL_FLAG_SACK; | |
384 | if (!(sysctl_flags & SYSCTL_FLAG_TSTAMPS)) | |
385 | tcp_header_size += TCPOLEN_SACKPERM_ALIGNED; | |
1da177e4 | 386 | } |
dfb4b9dc DM |
387 | } else if (unlikely(tp->rx_opt.eff_sacks)) { |
388 | /* A SACK is 2 pad bytes, a 2 byte header, plus | |
389 | * 2 32-bit sequence numbers for each SACK block. | |
390 | */ | |
391 | tcp_header_size += (TCPOLEN_SACK_BASE_ALIGNED + | |
392 | (tp->rx_opt.eff_sacks * | |
393 | TCPOLEN_SACK_PERBLOCK)); | |
394 | } | |
395 | ||
396 | if (tcp_packets_in_flight(tp) == 0) | |
397 | tcp_ca_event(sk, CA_EVENT_TX_START); | |
398 | ||
399 | th = (struct tcphdr *) skb_push(skb, tcp_header_size); | |
400 | skb->h.th = th; | |
401 | skb_set_owner_w(skb, sk); | |
402 | ||
403 | /* Build TCP header and checksum it. */ | |
404 | th->source = inet->sport; | |
405 | th->dest = inet->dport; | |
406 | th->seq = htonl(tcb->seq); | |
407 | th->ack_seq = htonl(tp->rcv_nxt); | |
408 | *(((__u16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | | |
409 | tcb->flags); | |
410 | ||
411 | if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) { | |
412 | /* RFC1323: The window in SYN & SYN/ACK segments | |
413 | * is never scaled. | |
414 | */ | |
415 | th->window = htons(tp->rcv_wnd); | |
416 | } else { | |
417 | th->window = htons(tcp_select_window(sk)); | |
418 | } | |
419 | th->check = 0; | |
420 | th->urg_ptr = 0; | |
1da177e4 | 421 | |
dfb4b9dc DM |
422 | if (unlikely(tp->urg_mode && |
423 | between(tp->snd_up, tcb->seq+1, tcb->seq+0xFFFF))) { | |
424 | th->urg_ptr = htons(tp->snd_up-tcb->seq); | |
425 | th->urg = 1; | |
426 | } | |
1da177e4 | 427 | |
dfb4b9dc DM |
428 | if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) { |
429 | tcp_syn_build_options((__u32 *)(th + 1), | |
430 | tcp_advertise_mss(sk), | |
431 | (sysctl_flags & SYSCTL_FLAG_TSTAMPS), | |
432 | (sysctl_flags & SYSCTL_FLAG_SACK), | |
433 | (sysctl_flags & SYSCTL_FLAG_WSCALE), | |
434 | tp->rx_opt.rcv_wscale, | |
435 | tcb->when, | |
436 | tp->rx_opt.ts_recent); | |
437 | } else { | |
438 | tcp_build_and_update_options((__u32 *)(th + 1), | |
439 | tp, tcb->when); | |
440 | TCP_ECN_send(sk, tp, skb, tcp_header_size); | |
441 | } | |
1da177e4 | 442 | |
8292a17a | 443 | icsk->icsk_af_ops->send_check(sk, skb->len, skb); |
1da177e4 | 444 | |
dfb4b9dc DM |
445 | if (likely(tcb->flags & TCPCB_FLAG_ACK)) |
446 | tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); | |
1da177e4 | 447 | |
dfb4b9dc DM |
448 | if (skb->len != tcp_header_size) |
449 | tcp_event_data_sent(tp, skb, sk); | |
1da177e4 | 450 | |
dfb4b9dc | 451 | TCP_INC_STATS(TCP_MIB_OUTSEGS); |
1da177e4 | 452 | |
8292a17a | 453 | err = icsk->icsk_af_ops->queue_xmit(skb, 0); |
dfb4b9dc DM |
454 | if (unlikely(err <= 0)) |
455 | return err; | |
456 | ||
457 | tcp_enter_cwr(sk); | |
458 | ||
459 | /* NET_XMIT_CN is special. It does not guarantee, | |
460 | * that this packet is lost. It tells that device | |
461 | * is about to start to drop packets or already | |
462 | * drops some packets of the same priority and | |
463 | * invokes us to send less aggressively. | |
464 | */ | |
465 | return err == NET_XMIT_CN ? 0 : err; | |
1da177e4 | 466 | |
1da177e4 LT |
467 | #undef SYSCTL_FLAG_TSTAMPS |
468 | #undef SYSCTL_FLAG_WSCALE | |
469 | #undef SYSCTL_FLAG_SACK | |
470 | } | |
471 | ||
472 | ||
473 | /* This routine just queue's the buffer | |
474 | * | |
475 | * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, | |
476 | * otherwise socket can stall. | |
477 | */ | |
478 | static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) | |
479 | { | |
480 | struct tcp_sock *tp = tcp_sk(sk); | |
481 | ||
482 | /* Advance write_seq and place onto the write_queue. */ | |
483 | tp->write_seq = TCP_SKB_CB(skb)->end_seq; | |
484 | skb_header_release(skb); | |
485 | __skb_queue_tail(&sk->sk_write_queue, skb); | |
486 | sk_charge_skb(sk, skb); | |
487 | ||
488 | /* Queue it, remembering where we must start sending. */ | |
489 | if (sk->sk_send_head == NULL) | |
490 | sk->sk_send_head = skb; | |
491 | } | |
492 | ||
846998ae | 493 | static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now) |
f6302d1d | 494 | { |
846998ae | 495 | if (skb->len <= mss_now || |
f6302d1d DM |
496 | !(sk->sk_route_caps & NETIF_F_TSO)) { |
497 | /* Avoid the costly divide in the normal | |
498 | * non-TSO case. | |
499 | */ | |
500 | skb_shinfo(skb)->tso_segs = 1; | |
501 | skb_shinfo(skb)->tso_size = 0; | |
502 | } else { | |
503 | unsigned int factor; | |
504 | ||
846998ae DM |
505 | factor = skb->len + (mss_now - 1); |
506 | factor /= mss_now; | |
f6302d1d | 507 | skb_shinfo(skb)->tso_segs = factor; |
846998ae | 508 | skb_shinfo(skb)->tso_size = mss_now; |
1da177e4 LT |
509 | } |
510 | } | |
511 | ||
1da177e4 LT |
512 | /* Function to create two new TCP segments. Shrinks the given segment |
513 | * to the specified size and appends a new segment with the rest of the | |
514 | * packet to the list. This won't be called frequently, I hope. | |
515 | * Remember, these are still headerless SKBs at this point. | |
516 | */ | |
6475be16 | 517 | int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss_now) |
1da177e4 LT |
518 | { |
519 | struct tcp_sock *tp = tcp_sk(sk); | |
520 | struct sk_buff *buff; | |
6475be16 | 521 | int nsize, old_factor; |
1da177e4 LT |
522 | u16 flags; |
523 | ||
b2cc99f0 | 524 | BUG_ON(len > skb->len); |
6a438bbe SH |
525 | |
526 | clear_all_retrans_hints(tp); | |
1da177e4 LT |
527 | nsize = skb_headlen(skb) - len; |
528 | if (nsize < 0) | |
529 | nsize = 0; | |
530 | ||
531 | if (skb_cloned(skb) && | |
532 | skb_is_nonlinear(skb) && | |
533 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) | |
534 | return -ENOMEM; | |
535 | ||
536 | /* Get a new skb... force flag on. */ | |
537 | buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC); | |
538 | if (buff == NULL) | |
539 | return -ENOMEM; /* We'll just try again later. */ | |
540 | sk_charge_skb(sk, buff); | |
541 | ||
542 | /* Correct the sequence numbers. */ | |
543 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
544 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
545 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
546 | ||
547 | /* PSH and FIN should only be set in the second packet. */ | |
548 | flags = TCP_SKB_CB(skb)->flags; | |
549 | TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH); | |
550 | TCP_SKB_CB(buff)->flags = flags; | |
e14c3caf | 551 | TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; |
1da177e4 LT |
552 | TCP_SKB_CB(skb)->sacked &= ~TCPCB_AT_TAIL; |
553 | ||
554 | if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_HW) { | |
555 | /* Copy and checksum data tail into the new buffer. */ | |
556 | buff->csum = csum_partial_copy_nocheck(skb->data + len, skb_put(buff, nsize), | |
557 | nsize, 0); | |
558 | ||
559 | skb_trim(skb, len); | |
560 | ||
561 | skb->csum = csum_block_sub(skb->csum, buff->csum, len); | |
562 | } else { | |
563 | skb->ip_summed = CHECKSUM_HW; | |
564 | skb_split(skb, buff, len); | |
565 | } | |
566 | ||
567 | buff->ip_summed = skb->ip_summed; | |
568 | ||
569 | /* Looks stupid, but our code really uses when of | |
570 | * skbs, which it never sent before. --ANK | |
571 | */ | |
572 | TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when; | |
a61bbcf2 | 573 | buff->tstamp = skb->tstamp; |
1da177e4 | 574 | |
6475be16 DM |
575 | old_factor = tcp_skb_pcount(skb); |
576 | ||
1da177e4 | 577 | /* Fix up tso_factor for both original and new SKB. */ |
846998ae DM |
578 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
579 | tcp_set_skb_tso_segs(sk, buff, mss_now); | |
1da177e4 | 580 | |
6475be16 DM |
581 | /* If this packet has been sent out already, we must |
582 | * adjust the various packet counters. | |
583 | */ | |
cf0b450c | 584 | if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { |
6475be16 DM |
585 | int diff = old_factor - tcp_skb_pcount(skb) - |
586 | tcp_skb_pcount(buff); | |
1da177e4 | 587 | |
6475be16 | 588 | tp->packets_out -= diff; |
e14c3caf HX |
589 | |
590 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
591 | tp->sacked_out -= diff; | |
592 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) | |
593 | tp->retrans_out -= diff; | |
594 | ||
6475be16 DM |
595 | if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) { |
596 | tp->lost_out -= diff; | |
597 | tp->left_out -= diff; | |
598 | } | |
83ca28be | 599 | |
6475be16 | 600 | if (diff > 0) { |
83ca28be HX |
601 | /* Adjust Reno SACK estimate. */ |
602 | if (!tp->rx_opt.sack_ok) { | |
603 | tp->sacked_out -= diff; | |
604 | if ((int)tp->sacked_out < 0) | |
605 | tp->sacked_out = 0; | |
606 | tcp_sync_left_out(tp); | |
607 | } | |
608 | ||
6475be16 DM |
609 | tp->fackets_out -= diff; |
610 | if ((int)tp->fackets_out < 0) | |
611 | tp->fackets_out = 0; | |
612 | } | |
1da177e4 LT |
613 | } |
614 | ||
615 | /* Link BUFF into the send queue. */ | |
f44b5271 | 616 | skb_header_release(buff); |
8728b834 | 617 | __skb_append(skb, buff, &sk->sk_write_queue); |
1da177e4 LT |
618 | |
619 | return 0; | |
620 | } | |
621 | ||
622 | /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c | |
623 | * eventually). The difference is that pulled data not copied, but | |
624 | * immediately discarded. | |
625 | */ | |
626 | static unsigned char *__pskb_trim_head(struct sk_buff *skb, int len) | |
627 | { | |
628 | int i, k, eat; | |
629 | ||
630 | eat = len; | |
631 | k = 0; | |
632 | for (i=0; i<skb_shinfo(skb)->nr_frags; i++) { | |
633 | if (skb_shinfo(skb)->frags[i].size <= eat) { | |
634 | put_page(skb_shinfo(skb)->frags[i].page); | |
635 | eat -= skb_shinfo(skb)->frags[i].size; | |
636 | } else { | |
637 | skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; | |
638 | if (eat) { | |
639 | skb_shinfo(skb)->frags[k].page_offset += eat; | |
640 | skb_shinfo(skb)->frags[k].size -= eat; | |
641 | eat = 0; | |
642 | } | |
643 | k++; | |
644 | } | |
645 | } | |
646 | skb_shinfo(skb)->nr_frags = k; | |
647 | ||
648 | skb->tail = skb->data; | |
649 | skb->data_len -= len; | |
650 | skb->len = skb->data_len; | |
651 | return skb->tail; | |
652 | } | |
653 | ||
654 | int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) | |
655 | { | |
656 | if (skb_cloned(skb) && | |
657 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) | |
658 | return -ENOMEM; | |
659 | ||
660 | if (len <= skb_headlen(skb)) { | |
661 | __skb_pull(skb, len); | |
662 | } else { | |
663 | if (__pskb_trim_head(skb, len-skb_headlen(skb)) == NULL) | |
664 | return -ENOMEM; | |
665 | } | |
666 | ||
667 | TCP_SKB_CB(skb)->seq += len; | |
668 | skb->ip_summed = CHECKSUM_HW; | |
669 | ||
670 | skb->truesize -= len; | |
671 | sk->sk_wmem_queued -= len; | |
672 | sk->sk_forward_alloc += len; | |
673 | sock_set_flag(sk, SOCK_QUEUE_SHRUNK); | |
674 | ||
675 | /* Any change of skb->len requires recalculation of tso | |
676 | * factor and mss. | |
677 | */ | |
678 | if (tcp_skb_pcount(skb) > 1) | |
846998ae | 679 | tcp_set_skb_tso_segs(sk, skb, tcp_current_mss(sk, 1)); |
1da177e4 LT |
680 | |
681 | return 0; | |
682 | } | |
683 | ||
684 | /* This function synchronize snd mss to current pmtu/exthdr set. | |
685 | ||
686 | tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts | |
687 | for TCP options, but includes only bare TCP header. | |
688 | ||
689 | tp->rx_opt.mss_clamp is mss negotiated at connection setup. | |
caa20d9a | 690 | It is minimum of user_mss and mss received with SYN. |
1da177e4 LT |
691 | It also does not include TCP options. |
692 | ||
d83d8461 | 693 | inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. |
1da177e4 LT |
694 | |
695 | tp->mss_cache is current effective sending mss, including | |
696 | all tcp options except for SACKs. It is evaluated, | |
697 | taking into account current pmtu, but never exceeds | |
698 | tp->rx_opt.mss_clamp. | |
699 | ||
700 | NOTE1. rfc1122 clearly states that advertised MSS | |
701 | DOES NOT include either tcp or ip options. | |
702 | ||
d83d8461 ACM |
703 | NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache |
704 | are READ ONLY outside this function. --ANK (980731) | |
1da177e4 LT |
705 | */ |
706 | ||
707 | unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) | |
708 | { | |
709 | struct tcp_sock *tp = tcp_sk(sk); | |
d83d8461 | 710 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
711 | /* Calculate base mss without TCP options: |
712 | It is MMS_S - sizeof(tcphdr) of rfc1122 | |
713 | */ | |
d83d8461 | 714 | int mss_now = (pmtu - icsk->icsk_af_ops->net_header_len - |
8292a17a | 715 | sizeof(struct tcphdr)); |
1da177e4 LT |
716 | |
717 | /* Clamp it (mss_clamp does not include tcp options) */ | |
718 | if (mss_now > tp->rx_opt.mss_clamp) | |
719 | mss_now = tp->rx_opt.mss_clamp; | |
720 | ||
721 | /* Now subtract optional transport overhead */ | |
d83d8461 | 722 | mss_now -= icsk->icsk_ext_hdr_len; |
1da177e4 LT |
723 | |
724 | /* Then reserve room for full set of TCP options and 8 bytes of data */ | |
725 | if (mss_now < 48) | |
726 | mss_now = 48; | |
727 | ||
728 | /* Now subtract TCP options size, not including SACKs */ | |
729 | mss_now -= tp->tcp_header_len - sizeof(struct tcphdr); | |
730 | ||
731 | /* Bound mss with half of window */ | |
732 | if (tp->max_window && mss_now > (tp->max_window>>1)) | |
733 | mss_now = max((tp->max_window>>1), 68U - tp->tcp_header_len); | |
734 | ||
735 | /* And store cached results */ | |
d83d8461 | 736 | icsk->icsk_pmtu_cookie = pmtu; |
c1b4a7e6 | 737 | tp->mss_cache = mss_now; |
1da177e4 LT |
738 | |
739 | return mss_now; | |
740 | } | |
741 | ||
742 | /* Compute the current effective MSS, taking SACKs and IP options, | |
743 | * and even PMTU discovery events into account. | |
744 | * | |
745 | * LARGESEND note: !urg_mode is overkill, only frames up to snd_up | |
746 | * cannot be large. However, taking into account rare use of URG, this | |
747 | * is not a big flaw. | |
748 | */ | |
c1b4a7e6 | 749 | unsigned int tcp_current_mss(struct sock *sk, int large_allowed) |
1da177e4 LT |
750 | { |
751 | struct tcp_sock *tp = tcp_sk(sk); | |
752 | struct dst_entry *dst = __sk_dst_get(sk); | |
c1b4a7e6 DM |
753 | u32 mss_now; |
754 | u16 xmit_size_goal; | |
755 | int doing_tso = 0; | |
756 | ||
757 | mss_now = tp->mss_cache; | |
758 | ||
759 | if (large_allowed && | |
760 | (sk->sk_route_caps & NETIF_F_TSO) && | |
761 | !tp->urg_mode) | |
762 | doing_tso = 1; | |
1da177e4 | 763 | |
1da177e4 LT |
764 | if (dst) { |
765 | u32 mtu = dst_mtu(dst); | |
d83d8461 | 766 | if (mtu != inet_csk(sk)->icsk_pmtu_cookie) |
1da177e4 LT |
767 | mss_now = tcp_sync_mss(sk, mtu); |
768 | } | |
769 | ||
c1b4a7e6 DM |
770 | if (tp->rx_opt.eff_sacks) |
771 | mss_now -= (TCPOLEN_SACK_BASE_ALIGNED + | |
772 | (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK)); | |
1da177e4 | 773 | |
c1b4a7e6 | 774 | xmit_size_goal = mss_now; |
1da177e4 | 775 | |
c1b4a7e6 | 776 | if (doing_tso) { |
8292a17a ACM |
777 | xmit_size_goal = (65535 - |
778 | inet_csk(sk)->icsk_af_ops->net_header_len - | |
d83d8461 ACM |
779 | inet_csk(sk)->icsk_ext_hdr_len - |
780 | tp->tcp_header_len); | |
1da177e4 | 781 | |
c1b4a7e6 DM |
782 | if (tp->max_window && |
783 | (xmit_size_goal > (tp->max_window >> 1))) | |
784 | xmit_size_goal = max((tp->max_window >> 1), | |
785 | 68U - tp->tcp_header_len); | |
1da177e4 | 786 | |
c1b4a7e6 | 787 | xmit_size_goal -= (xmit_size_goal % mss_now); |
1da177e4 | 788 | } |
c1b4a7e6 | 789 | tp->xmit_size_goal = xmit_size_goal; |
1da177e4 | 790 | |
1da177e4 LT |
791 | return mss_now; |
792 | } | |
793 | ||
a762a980 DM |
794 | /* Congestion window validation. (RFC2861) */ |
795 | ||
40efc6fa | 796 | static void tcp_cwnd_validate(struct sock *sk, struct tcp_sock *tp) |
a762a980 DM |
797 | { |
798 | __u32 packets_out = tp->packets_out; | |
799 | ||
800 | if (packets_out >= tp->snd_cwnd) { | |
801 | /* Network is feed fully. */ | |
802 | tp->snd_cwnd_used = 0; | |
803 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
804 | } else { | |
805 | /* Network starves. */ | |
806 | if (tp->packets_out > tp->snd_cwnd_used) | |
807 | tp->snd_cwnd_used = tp->packets_out; | |
808 | ||
463c84b9 | 809 | if ((s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) |
a762a980 DM |
810 | tcp_cwnd_application_limited(sk); |
811 | } | |
812 | } | |
813 | ||
c1b4a7e6 DM |
814 | static unsigned int tcp_window_allows(struct tcp_sock *tp, struct sk_buff *skb, unsigned int mss_now, unsigned int cwnd) |
815 | { | |
816 | u32 window, cwnd_len; | |
817 | ||
818 | window = (tp->snd_una + tp->snd_wnd - TCP_SKB_CB(skb)->seq); | |
819 | cwnd_len = mss_now * cwnd; | |
820 | return min(window, cwnd_len); | |
821 | } | |
822 | ||
823 | /* Can at least one segment of SKB be sent right now, according to the | |
824 | * congestion window rules? If so, return how many segments are allowed. | |
825 | */ | |
826 | static inline unsigned int tcp_cwnd_test(struct tcp_sock *tp, struct sk_buff *skb) | |
827 | { | |
828 | u32 in_flight, cwnd; | |
829 | ||
830 | /* Don't be strict about the congestion window for the final FIN. */ | |
831 | if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) | |
832 | return 1; | |
833 | ||
834 | in_flight = tcp_packets_in_flight(tp); | |
835 | cwnd = tp->snd_cwnd; | |
836 | if (in_flight < cwnd) | |
837 | return (cwnd - in_flight); | |
838 | ||
839 | return 0; | |
840 | } | |
841 | ||
842 | /* This must be invoked the first time we consider transmitting | |
843 | * SKB onto the wire. | |
844 | */ | |
40efc6fa | 845 | static int tcp_init_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now) |
c1b4a7e6 DM |
846 | { |
847 | int tso_segs = tcp_skb_pcount(skb); | |
848 | ||
846998ae DM |
849 | if (!tso_segs || |
850 | (tso_segs > 1 && | |
851 | skb_shinfo(skb)->tso_size != mss_now)) { | |
852 | tcp_set_skb_tso_segs(sk, skb, mss_now); | |
c1b4a7e6 DM |
853 | tso_segs = tcp_skb_pcount(skb); |
854 | } | |
855 | return tso_segs; | |
856 | } | |
857 | ||
858 | static inline int tcp_minshall_check(const struct tcp_sock *tp) | |
859 | { | |
860 | return after(tp->snd_sml,tp->snd_una) && | |
861 | !after(tp->snd_sml, tp->snd_nxt); | |
862 | } | |
863 | ||
864 | /* Return 0, if packet can be sent now without violation Nagle's rules: | |
865 | * 1. It is full sized. | |
866 | * 2. Or it contains FIN. (already checked by caller) | |
867 | * 3. Or TCP_NODELAY was set. | |
868 | * 4. Or TCP_CORK is not set, and all sent packets are ACKed. | |
869 | * With Minshall's modification: all sent small packets are ACKed. | |
870 | */ | |
871 | ||
872 | static inline int tcp_nagle_check(const struct tcp_sock *tp, | |
873 | const struct sk_buff *skb, | |
874 | unsigned mss_now, int nonagle) | |
875 | { | |
876 | return (skb->len < mss_now && | |
877 | ((nonagle&TCP_NAGLE_CORK) || | |
878 | (!nonagle && | |
879 | tp->packets_out && | |
880 | tcp_minshall_check(tp)))); | |
881 | } | |
882 | ||
883 | /* Return non-zero if the Nagle test allows this packet to be | |
884 | * sent now. | |
885 | */ | |
886 | static inline int tcp_nagle_test(struct tcp_sock *tp, struct sk_buff *skb, | |
887 | unsigned int cur_mss, int nonagle) | |
888 | { | |
889 | /* Nagle rule does not apply to frames, which sit in the middle of the | |
890 | * write_queue (they have no chances to get new data). | |
891 | * | |
892 | * This is implemented in the callers, where they modify the 'nonagle' | |
893 | * argument based upon the location of SKB in the send queue. | |
894 | */ | |
895 | if (nonagle & TCP_NAGLE_PUSH) | |
896 | return 1; | |
897 | ||
898 | /* Don't use the nagle rule for urgent data (or for the final FIN). */ | |
899 | if (tp->urg_mode || | |
900 | (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)) | |
901 | return 1; | |
902 | ||
903 | if (!tcp_nagle_check(tp, skb, cur_mss, nonagle)) | |
904 | return 1; | |
905 | ||
906 | return 0; | |
907 | } | |
908 | ||
909 | /* Does at least the first segment of SKB fit into the send window? */ | |
910 | static inline int tcp_snd_wnd_test(struct tcp_sock *tp, struct sk_buff *skb, unsigned int cur_mss) | |
911 | { | |
912 | u32 end_seq = TCP_SKB_CB(skb)->end_seq; | |
913 | ||
914 | if (skb->len > cur_mss) | |
915 | end_seq = TCP_SKB_CB(skb)->seq + cur_mss; | |
916 | ||
917 | return !after(end_seq, tp->snd_una + tp->snd_wnd); | |
918 | } | |
919 | ||
920 | /* This checks if the data bearing packet SKB (usually sk->sk_send_head) | |
921 | * should be put on the wire right now. If so, it returns the number of | |
922 | * packets allowed by the congestion window. | |
923 | */ | |
924 | static unsigned int tcp_snd_test(struct sock *sk, struct sk_buff *skb, | |
925 | unsigned int cur_mss, int nonagle) | |
926 | { | |
927 | struct tcp_sock *tp = tcp_sk(sk); | |
928 | unsigned int cwnd_quota; | |
929 | ||
846998ae | 930 | tcp_init_tso_segs(sk, skb, cur_mss); |
c1b4a7e6 DM |
931 | |
932 | if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) | |
933 | return 0; | |
934 | ||
935 | cwnd_quota = tcp_cwnd_test(tp, skb); | |
936 | if (cwnd_quota && | |
937 | !tcp_snd_wnd_test(tp, skb, cur_mss)) | |
938 | cwnd_quota = 0; | |
939 | ||
940 | return cwnd_quota; | |
941 | } | |
942 | ||
943 | static inline int tcp_skb_is_last(const struct sock *sk, | |
944 | const struct sk_buff *skb) | |
945 | { | |
946 | return skb->next == (struct sk_buff *)&sk->sk_write_queue; | |
947 | } | |
948 | ||
949 | int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp) | |
950 | { | |
951 | struct sk_buff *skb = sk->sk_send_head; | |
952 | ||
953 | return (skb && | |
954 | tcp_snd_test(sk, skb, tcp_current_mss(sk, 1), | |
955 | (tcp_skb_is_last(sk, skb) ? | |
956 | TCP_NAGLE_PUSH : | |
957 | tp->nonagle))); | |
958 | } | |
959 | ||
960 | /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet | |
961 | * which is put after SKB on the list. It is very much like | |
962 | * tcp_fragment() except that it may make several kinds of assumptions | |
963 | * in order to speed up the splitting operation. In particular, we | |
964 | * know that all the data is in scatter-gather pages, and that the | |
965 | * packet has never been sent out before (and thus is not cloned). | |
966 | */ | |
846998ae | 967 | static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, unsigned int mss_now) |
c1b4a7e6 DM |
968 | { |
969 | struct sk_buff *buff; | |
970 | int nlen = skb->len - len; | |
971 | u16 flags; | |
972 | ||
973 | /* All of a TSO frame must be composed of paged data. */ | |
c8ac3774 HX |
974 | if (skb->len != skb->data_len) |
975 | return tcp_fragment(sk, skb, len, mss_now); | |
c1b4a7e6 DM |
976 | |
977 | buff = sk_stream_alloc_pskb(sk, 0, 0, GFP_ATOMIC); | |
978 | if (unlikely(buff == NULL)) | |
979 | return -ENOMEM; | |
980 | ||
981 | buff->truesize = nlen; | |
982 | skb->truesize -= nlen; | |
983 | ||
984 | /* Correct the sequence numbers. */ | |
985 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
986 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
987 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
988 | ||
989 | /* PSH and FIN should only be set in the second packet. */ | |
990 | flags = TCP_SKB_CB(skb)->flags; | |
991 | TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH); | |
992 | TCP_SKB_CB(buff)->flags = flags; | |
993 | ||
994 | /* This packet was never sent out yet, so no SACK bits. */ | |
995 | TCP_SKB_CB(buff)->sacked = 0; | |
996 | ||
997 | buff->ip_summed = skb->ip_summed = CHECKSUM_HW; | |
998 | skb_split(skb, buff, len); | |
999 | ||
1000 | /* Fix up tso_factor for both original and new SKB. */ | |
846998ae DM |
1001 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
1002 | tcp_set_skb_tso_segs(sk, buff, mss_now); | |
c1b4a7e6 DM |
1003 | |
1004 | /* Link BUFF into the send queue. */ | |
1005 | skb_header_release(buff); | |
8728b834 | 1006 | __skb_append(skb, buff, &sk->sk_write_queue); |
c1b4a7e6 DM |
1007 | |
1008 | return 0; | |
1009 | } | |
1010 | ||
1011 | /* Try to defer sending, if possible, in order to minimize the amount | |
1012 | * of TSO splitting we do. View it as a kind of TSO Nagle test. | |
1013 | * | |
1014 | * This algorithm is from John Heffner. | |
1015 | */ | |
1016 | static int tcp_tso_should_defer(struct sock *sk, struct tcp_sock *tp, struct sk_buff *skb) | |
1017 | { | |
6687e988 | 1018 | const struct inet_connection_sock *icsk = inet_csk(sk); |
c1b4a7e6 DM |
1019 | u32 send_win, cong_win, limit, in_flight; |
1020 | ||
1021 | if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) | |
1022 | return 0; | |
1023 | ||
6687e988 | 1024 | if (icsk->icsk_ca_state != TCP_CA_Open) |
908a75c1 DM |
1025 | return 0; |
1026 | ||
c1b4a7e6 DM |
1027 | in_flight = tcp_packets_in_flight(tp); |
1028 | ||
1029 | BUG_ON(tcp_skb_pcount(skb) <= 1 || | |
1030 | (tp->snd_cwnd <= in_flight)); | |
1031 | ||
1032 | send_win = (tp->snd_una + tp->snd_wnd) - TCP_SKB_CB(skb)->seq; | |
1033 | ||
1034 | /* From in_flight test above, we know that cwnd > in_flight. */ | |
1035 | cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache; | |
1036 | ||
1037 | limit = min(send_win, cong_win); | |
1038 | ||
ba244fe9 DM |
1039 | /* If a full-sized TSO skb can be sent, do it. */ |
1040 | if (limit >= 65536) | |
1041 | return 0; | |
1042 | ||
c1b4a7e6 DM |
1043 | if (sysctl_tcp_tso_win_divisor) { |
1044 | u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); | |
1045 | ||
1046 | /* If at least some fraction of a window is available, | |
1047 | * just use it. | |
1048 | */ | |
1049 | chunk /= sysctl_tcp_tso_win_divisor; | |
1050 | if (limit >= chunk) | |
1051 | return 0; | |
1052 | } else { | |
1053 | /* Different approach, try not to defer past a single | |
1054 | * ACK. Receiver should ACK every other full sized | |
1055 | * frame, so if we have space for more than 3 frames | |
1056 | * then send now. | |
1057 | */ | |
1058 | if (limit > tcp_max_burst(tp) * tp->mss_cache) | |
1059 | return 0; | |
1060 | } | |
1061 | ||
1062 | /* Ok, it looks like it is advisable to defer. */ | |
1063 | return 1; | |
1064 | } | |
1065 | ||
1da177e4 LT |
1066 | /* This routine writes packets to the network. It advances the |
1067 | * send_head. This happens as incoming acks open up the remote | |
1068 | * window for us. | |
1069 | * | |
1070 | * Returns 1, if no segments are in flight and we have queued segments, but | |
1071 | * cannot send anything now because of SWS or another problem. | |
1072 | */ | |
a2e2a59c | 1073 | static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle) |
1da177e4 LT |
1074 | { |
1075 | struct tcp_sock *tp = tcp_sk(sk); | |
92df7b51 | 1076 | struct sk_buff *skb; |
c1b4a7e6 DM |
1077 | unsigned int tso_segs, sent_pkts; |
1078 | int cwnd_quota; | |
1da177e4 LT |
1079 | |
1080 | /* If we are closed, the bytes will have to remain here. | |
1081 | * In time closedown will finish, we empty the write queue and all | |
1082 | * will be happy. | |
1083 | */ | |
92df7b51 DM |
1084 | if (unlikely(sk->sk_state == TCP_CLOSE)) |
1085 | return 0; | |
1da177e4 | 1086 | |
92df7b51 | 1087 | sent_pkts = 0; |
b68e9f85 | 1088 | while ((skb = sk->sk_send_head)) { |
c8ac3774 HX |
1089 | unsigned int limit; |
1090 | ||
b68e9f85 | 1091 | tso_segs = tcp_init_tso_segs(sk, skb, mss_now); |
c1b4a7e6 | 1092 | BUG_ON(!tso_segs); |
aa93466b | 1093 | |
b68e9f85 HX |
1094 | cwnd_quota = tcp_cwnd_test(tp, skb); |
1095 | if (!cwnd_quota) | |
1096 | break; | |
1097 | ||
1098 | if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) | |
1099 | break; | |
1100 | ||
c1b4a7e6 DM |
1101 | if (tso_segs == 1) { |
1102 | if (unlikely(!tcp_nagle_test(tp, skb, mss_now, | |
1103 | (tcp_skb_is_last(sk, skb) ? | |
1104 | nonagle : TCP_NAGLE_PUSH)))) | |
1105 | break; | |
1106 | } else { | |
1107 | if (tcp_tso_should_defer(sk, tp, skb)) | |
1108 | break; | |
1109 | } | |
aa93466b | 1110 | |
c8ac3774 | 1111 | limit = mss_now; |
c1b4a7e6 | 1112 | if (tso_segs > 1) { |
c8ac3774 HX |
1113 | limit = tcp_window_allows(tp, skb, |
1114 | mss_now, cwnd_quota); | |
c1b4a7e6 DM |
1115 | |
1116 | if (skb->len < limit) { | |
1117 | unsigned int trim = skb->len % mss_now; | |
aa93466b | 1118 | |
c1b4a7e6 DM |
1119 | if (trim) |
1120 | limit = skb->len - trim; | |
1121 | } | |
92df7b51 | 1122 | } |
1da177e4 | 1123 | |
c8ac3774 HX |
1124 | if (skb->len > limit && |
1125 | unlikely(tso_fragment(sk, skb, limit, mss_now))) | |
1126 | break; | |
1127 | ||
92df7b51 | 1128 | TCP_SKB_CB(skb)->when = tcp_time_stamp; |
c1b4a7e6 | 1129 | |
dfb4b9dc | 1130 | if (unlikely(tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC))) |
92df7b51 | 1131 | break; |
1da177e4 | 1132 | |
92df7b51 DM |
1133 | /* Advance the send_head. This one is sent out. |
1134 | * This call will increment packets_out. | |
1135 | */ | |
1136 | update_send_head(sk, tp, skb); | |
1da177e4 | 1137 | |
92df7b51 | 1138 | tcp_minshall_update(tp, mss_now, skb); |
aa93466b | 1139 | sent_pkts++; |
92df7b51 | 1140 | } |
1da177e4 | 1141 | |
aa93466b | 1142 | if (likely(sent_pkts)) { |
92df7b51 DM |
1143 | tcp_cwnd_validate(sk, tp); |
1144 | return 0; | |
1da177e4 | 1145 | } |
92df7b51 | 1146 | return !tp->packets_out && sk->sk_send_head; |
1da177e4 LT |
1147 | } |
1148 | ||
a762a980 DM |
1149 | /* Push out any pending frames which were held back due to |
1150 | * TCP_CORK or attempt at coalescing tiny packets. | |
1151 | * The socket must be locked by the caller. | |
1152 | */ | |
1153 | void __tcp_push_pending_frames(struct sock *sk, struct tcp_sock *tp, | |
a2e2a59c | 1154 | unsigned int cur_mss, int nonagle) |
a762a980 DM |
1155 | { |
1156 | struct sk_buff *skb = sk->sk_send_head; | |
1157 | ||
1158 | if (skb) { | |
55c97f3e | 1159 | if (tcp_write_xmit(sk, cur_mss, nonagle)) |
a762a980 DM |
1160 | tcp_check_probe_timer(sk, tp); |
1161 | } | |
1162 | } | |
1163 | ||
c1b4a7e6 DM |
1164 | /* Send _single_ skb sitting at the send head. This function requires |
1165 | * true push pending frames to setup probe timer etc. | |
1166 | */ | |
1167 | void tcp_push_one(struct sock *sk, unsigned int mss_now) | |
1168 | { | |
1169 | struct tcp_sock *tp = tcp_sk(sk); | |
1170 | struct sk_buff *skb = sk->sk_send_head; | |
1171 | unsigned int tso_segs, cwnd_quota; | |
1172 | ||
1173 | BUG_ON(!skb || skb->len < mss_now); | |
1174 | ||
846998ae | 1175 | tso_segs = tcp_init_tso_segs(sk, skb, mss_now); |
c1b4a7e6 DM |
1176 | cwnd_quota = tcp_snd_test(sk, skb, mss_now, TCP_NAGLE_PUSH); |
1177 | ||
1178 | if (likely(cwnd_quota)) { | |
c8ac3774 HX |
1179 | unsigned int limit; |
1180 | ||
c1b4a7e6 DM |
1181 | BUG_ON(!tso_segs); |
1182 | ||
c8ac3774 | 1183 | limit = mss_now; |
c1b4a7e6 | 1184 | if (tso_segs > 1) { |
c8ac3774 HX |
1185 | limit = tcp_window_allows(tp, skb, |
1186 | mss_now, cwnd_quota); | |
c1b4a7e6 DM |
1187 | |
1188 | if (skb->len < limit) { | |
1189 | unsigned int trim = skb->len % mss_now; | |
1190 | ||
1191 | if (trim) | |
1192 | limit = skb->len - trim; | |
1193 | } | |
c1b4a7e6 DM |
1194 | } |
1195 | ||
c8ac3774 HX |
1196 | if (skb->len > limit && |
1197 | unlikely(tso_fragment(sk, skb, limit, mss_now))) | |
1198 | return; | |
1199 | ||
c1b4a7e6 DM |
1200 | /* Send it out now. */ |
1201 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
1202 | ||
dfb4b9dc | 1203 | if (likely(!tcp_transmit_skb(sk, skb, 1, sk->sk_allocation))) { |
c1b4a7e6 DM |
1204 | update_send_head(sk, tp, skb); |
1205 | tcp_cwnd_validate(sk, tp); | |
1206 | return; | |
1207 | } | |
1208 | } | |
1209 | } | |
1210 | ||
1da177e4 LT |
1211 | /* This function returns the amount that we can raise the |
1212 | * usable window based on the following constraints | |
1213 | * | |
1214 | * 1. The window can never be shrunk once it is offered (RFC 793) | |
1215 | * 2. We limit memory per socket | |
1216 | * | |
1217 | * RFC 1122: | |
1218 | * "the suggested [SWS] avoidance algorithm for the receiver is to keep | |
1219 | * RECV.NEXT + RCV.WIN fixed until: | |
1220 | * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" | |
1221 | * | |
1222 | * i.e. don't raise the right edge of the window until you can raise | |
1223 | * it at least MSS bytes. | |
1224 | * | |
1225 | * Unfortunately, the recommended algorithm breaks header prediction, | |
1226 | * since header prediction assumes th->window stays fixed. | |
1227 | * | |
1228 | * Strictly speaking, keeping th->window fixed violates the receiver | |
1229 | * side SWS prevention criteria. The problem is that under this rule | |
1230 | * a stream of single byte packets will cause the right side of the | |
1231 | * window to always advance by a single byte. | |
1232 | * | |
1233 | * Of course, if the sender implements sender side SWS prevention | |
1234 | * then this will not be a problem. | |
1235 | * | |
1236 | * BSD seems to make the following compromise: | |
1237 | * | |
1238 | * If the free space is less than the 1/4 of the maximum | |
1239 | * space available and the free space is less than 1/2 mss, | |
1240 | * then set the window to 0. | |
1241 | * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] | |
1242 | * Otherwise, just prevent the window from shrinking | |
1243 | * and from being larger than the largest representable value. | |
1244 | * | |
1245 | * This prevents incremental opening of the window in the regime | |
1246 | * where TCP is limited by the speed of the reader side taking | |
1247 | * data out of the TCP receive queue. It does nothing about | |
1248 | * those cases where the window is constrained on the sender side | |
1249 | * because the pipeline is full. | |
1250 | * | |
1251 | * BSD also seems to "accidentally" limit itself to windows that are a | |
1252 | * multiple of MSS, at least until the free space gets quite small. | |
1253 | * This would appear to be a side effect of the mbuf implementation. | |
1254 | * Combining these two algorithms results in the observed behavior | |
1255 | * of having a fixed window size at almost all times. | |
1256 | * | |
1257 | * Below we obtain similar behavior by forcing the offered window to | |
1258 | * a multiple of the mss when it is feasible to do so. | |
1259 | * | |
1260 | * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. | |
1261 | * Regular options like TIMESTAMP are taken into account. | |
1262 | */ | |
1263 | u32 __tcp_select_window(struct sock *sk) | |
1264 | { | |
463c84b9 | 1265 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 1266 | struct tcp_sock *tp = tcp_sk(sk); |
caa20d9a | 1267 | /* MSS for the peer's data. Previous versions used mss_clamp |
1da177e4 LT |
1268 | * here. I don't know if the value based on our guesses |
1269 | * of peer's MSS is better for the performance. It's more correct | |
1270 | * but may be worse for the performance because of rcv_mss | |
1271 | * fluctuations. --SAW 1998/11/1 | |
1272 | */ | |
463c84b9 | 1273 | int mss = icsk->icsk_ack.rcv_mss; |
1da177e4 LT |
1274 | int free_space = tcp_space(sk); |
1275 | int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk)); | |
1276 | int window; | |
1277 | ||
1278 | if (mss > full_space) | |
1279 | mss = full_space; | |
1280 | ||
1281 | if (free_space < full_space/2) { | |
463c84b9 | 1282 | icsk->icsk_ack.quick = 0; |
1da177e4 LT |
1283 | |
1284 | if (tcp_memory_pressure) | |
1285 | tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U*tp->advmss); | |
1286 | ||
1287 | if (free_space < mss) | |
1288 | return 0; | |
1289 | } | |
1290 | ||
1291 | if (free_space > tp->rcv_ssthresh) | |
1292 | free_space = tp->rcv_ssthresh; | |
1293 | ||
1294 | /* Don't do rounding if we are using window scaling, since the | |
1295 | * scaled window will not line up with the MSS boundary anyway. | |
1296 | */ | |
1297 | window = tp->rcv_wnd; | |
1298 | if (tp->rx_opt.rcv_wscale) { | |
1299 | window = free_space; | |
1300 | ||
1301 | /* Advertise enough space so that it won't get scaled away. | |
1302 | * Import case: prevent zero window announcement if | |
1303 | * 1<<rcv_wscale > mss. | |
1304 | */ | |
1305 | if (((window >> tp->rx_opt.rcv_wscale) << tp->rx_opt.rcv_wscale) != window) | |
1306 | window = (((window >> tp->rx_opt.rcv_wscale) + 1) | |
1307 | << tp->rx_opt.rcv_wscale); | |
1308 | } else { | |
1309 | /* Get the largest window that is a nice multiple of mss. | |
1310 | * Window clamp already applied above. | |
1311 | * If our current window offering is within 1 mss of the | |
1312 | * free space we just keep it. This prevents the divide | |
1313 | * and multiply from happening most of the time. | |
1314 | * We also don't do any window rounding when the free space | |
1315 | * is too small. | |
1316 | */ | |
1317 | if (window <= free_space - mss || window > free_space) | |
1318 | window = (free_space/mss)*mss; | |
1319 | } | |
1320 | ||
1321 | return window; | |
1322 | } | |
1323 | ||
1324 | /* Attempt to collapse two adjacent SKB's during retransmission. */ | |
1325 | static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int mss_now) | |
1326 | { | |
1327 | struct tcp_sock *tp = tcp_sk(sk); | |
1328 | struct sk_buff *next_skb = skb->next; | |
1329 | ||
1330 | /* The first test we must make is that neither of these two | |
1331 | * SKB's are still referenced by someone else. | |
1332 | */ | |
1333 | if (!skb_cloned(skb) && !skb_cloned(next_skb)) { | |
1334 | int skb_size = skb->len, next_skb_size = next_skb->len; | |
1335 | u16 flags = TCP_SKB_CB(skb)->flags; | |
1336 | ||
1337 | /* Also punt if next skb has been SACK'd. */ | |
1338 | if(TCP_SKB_CB(next_skb)->sacked & TCPCB_SACKED_ACKED) | |
1339 | return; | |
1340 | ||
1341 | /* Next skb is out of window. */ | |
1342 | if (after(TCP_SKB_CB(next_skb)->end_seq, tp->snd_una+tp->snd_wnd)) | |
1343 | return; | |
1344 | ||
1345 | /* Punt if not enough space exists in the first SKB for | |
1346 | * the data in the second, or the total combined payload | |
1347 | * would exceed the MSS. | |
1348 | */ | |
1349 | if ((next_skb_size > skb_tailroom(skb)) || | |
1350 | ((skb_size + next_skb_size) > mss_now)) | |
1351 | return; | |
1352 | ||
1353 | BUG_ON(tcp_skb_pcount(skb) != 1 || | |
1354 | tcp_skb_pcount(next_skb) != 1); | |
1355 | ||
6a438bbe SH |
1356 | /* changing transmit queue under us so clear hints */ |
1357 | clear_all_retrans_hints(tp); | |
1358 | ||
1359 | /* Ok. We will be able to collapse the packet. */ | |
8728b834 | 1360 | __skb_unlink(next_skb, &sk->sk_write_queue); |
1da177e4 LT |
1361 | |
1362 | memcpy(skb_put(skb, next_skb_size), next_skb->data, next_skb_size); | |
1363 | ||
1364 | if (next_skb->ip_summed == CHECKSUM_HW) | |
1365 | skb->ip_summed = CHECKSUM_HW; | |
1366 | ||
1367 | if (skb->ip_summed != CHECKSUM_HW) | |
1368 | skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size); | |
1369 | ||
1370 | /* Update sequence range on original skb. */ | |
1371 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; | |
1372 | ||
1373 | /* Merge over control information. */ | |
1374 | flags |= TCP_SKB_CB(next_skb)->flags; /* This moves PSH/FIN etc. over */ | |
1375 | TCP_SKB_CB(skb)->flags = flags; | |
1376 | ||
1377 | /* All done, get rid of second SKB and account for it so | |
1378 | * packet counting does not break. | |
1379 | */ | |
1380 | TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked&(TCPCB_EVER_RETRANS|TCPCB_AT_TAIL); | |
1381 | if (TCP_SKB_CB(next_skb)->sacked&TCPCB_SACKED_RETRANS) | |
1382 | tp->retrans_out -= tcp_skb_pcount(next_skb); | |
1383 | if (TCP_SKB_CB(next_skb)->sacked&TCPCB_LOST) { | |
1384 | tp->lost_out -= tcp_skb_pcount(next_skb); | |
1385 | tp->left_out -= tcp_skb_pcount(next_skb); | |
1386 | } | |
1387 | /* Reno case is special. Sigh... */ | |
1388 | if (!tp->rx_opt.sack_ok && tp->sacked_out) { | |
1389 | tcp_dec_pcount_approx(&tp->sacked_out, next_skb); | |
1390 | tp->left_out -= tcp_skb_pcount(next_skb); | |
1391 | } | |
1392 | ||
1393 | /* Not quite right: it can be > snd.fack, but | |
1394 | * it is better to underestimate fackets. | |
1395 | */ | |
1396 | tcp_dec_pcount_approx(&tp->fackets_out, next_skb); | |
1397 | tcp_packets_out_dec(tp, next_skb); | |
1398 | sk_stream_free_skb(sk, next_skb); | |
1399 | } | |
1400 | } | |
1401 | ||
1402 | /* Do a simple retransmit without using the backoff mechanisms in | |
1403 | * tcp_timer. This is used for path mtu discovery. | |
1404 | * The socket is already locked here. | |
1405 | */ | |
1406 | void tcp_simple_retransmit(struct sock *sk) | |
1407 | { | |
6687e988 | 1408 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
1409 | struct tcp_sock *tp = tcp_sk(sk); |
1410 | struct sk_buff *skb; | |
1411 | unsigned int mss = tcp_current_mss(sk, 0); | |
1412 | int lost = 0; | |
1413 | ||
1414 | sk_stream_for_retrans_queue(skb, sk) { | |
1415 | if (skb->len > mss && | |
1416 | !(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED)) { | |
1417 | if (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) { | |
1418 | TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS; | |
1419 | tp->retrans_out -= tcp_skb_pcount(skb); | |
1420 | } | |
1421 | if (!(TCP_SKB_CB(skb)->sacked&TCPCB_LOST)) { | |
1422 | TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; | |
1423 | tp->lost_out += tcp_skb_pcount(skb); | |
1424 | lost = 1; | |
1425 | } | |
1426 | } | |
1427 | } | |
1428 | ||
6a438bbe SH |
1429 | clear_all_retrans_hints(tp); |
1430 | ||
1da177e4 LT |
1431 | if (!lost) |
1432 | return; | |
1433 | ||
1434 | tcp_sync_left_out(tp); | |
1435 | ||
1436 | /* Don't muck with the congestion window here. | |
1437 | * Reason is that we do not increase amount of _data_ | |
1438 | * in network, but units changed and effective | |
1439 | * cwnd/ssthresh really reduced now. | |
1440 | */ | |
6687e988 | 1441 | if (icsk->icsk_ca_state != TCP_CA_Loss) { |
1da177e4 | 1442 | tp->high_seq = tp->snd_nxt; |
6687e988 | 1443 | tp->snd_ssthresh = tcp_current_ssthresh(sk); |
1da177e4 LT |
1444 | tp->prior_ssthresh = 0; |
1445 | tp->undo_marker = 0; | |
6687e988 | 1446 | tcp_set_ca_state(sk, TCP_CA_Loss); |
1da177e4 LT |
1447 | } |
1448 | tcp_xmit_retransmit_queue(sk); | |
1449 | } | |
1450 | ||
1451 | /* This retransmits one SKB. Policy decisions and retransmit queue | |
1452 | * state updates are done by the caller. Returns non-zero if an | |
1453 | * error occurred which prevented the send. | |
1454 | */ | |
1455 | int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) | |
1456 | { | |
1457 | struct tcp_sock *tp = tcp_sk(sk); | |
1458 | unsigned int cur_mss = tcp_current_mss(sk, 0); | |
1459 | int err; | |
1460 | ||
1461 | /* Do not sent more than we queued. 1/4 is reserved for possible | |
caa20d9a | 1462 | * copying overhead: fragmentation, tunneling, mangling etc. |
1da177e4 LT |
1463 | */ |
1464 | if (atomic_read(&sk->sk_wmem_alloc) > | |
1465 | min(sk->sk_wmem_queued + (sk->sk_wmem_queued >> 2), sk->sk_sndbuf)) | |
1466 | return -EAGAIN; | |
1467 | ||
1468 | if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { | |
1469 | if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) | |
1470 | BUG(); | |
1da177e4 LT |
1471 | if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) |
1472 | return -ENOMEM; | |
1473 | } | |
1474 | ||
1475 | /* If receiver has shrunk his window, and skb is out of | |
1476 | * new window, do not retransmit it. The exception is the | |
1477 | * case, when window is shrunk to zero. In this case | |
1478 | * our retransmit serves as a zero window probe. | |
1479 | */ | |
1480 | if (!before(TCP_SKB_CB(skb)->seq, tp->snd_una+tp->snd_wnd) | |
1481 | && TCP_SKB_CB(skb)->seq != tp->snd_una) | |
1482 | return -EAGAIN; | |
1483 | ||
1484 | if (skb->len > cur_mss) { | |
846998ae | 1485 | if (tcp_fragment(sk, skb, cur_mss, cur_mss)) |
1da177e4 | 1486 | return -ENOMEM; /* We'll try again later. */ |
1da177e4 LT |
1487 | } |
1488 | ||
1489 | /* Collapse two adjacent packets if worthwhile and we can. */ | |
1490 | if(!(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_SYN) && | |
1491 | (skb->len < (cur_mss >> 1)) && | |
1492 | (skb->next != sk->sk_send_head) && | |
1493 | (skb->next != (struct sk_buff *)&sk->sk_write_queue) && | |
1494 | (skb_shinfo(skb)->nr_frags == 0 && skb_shinfo(skb->next)->nr_frags == 0) && | |
1495 | (tcp_skb_pcount(skb) == 1 && tcp_skb_pcount(skb->next) == 1) && | |
1496 | (sysctl_tcp_retrans_collapse != 0)) | |
1497 | tcp_retrans_try_collapse(sk, skb, cur_mss); | |
1498 | ||
8292a17a | 1499 | if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) |
1da177e4 LT |
1500 | return -EHOSTUNREACH; /* Routing failure or similar. */ |
1501 | ||
1502 | /* Some Solaris stacks overoptimize and ignore the FIN on a | |
1503 | * retransmit when old data is attached. So strip it off | |
1504 | * since it is cheap to do so and saves bytes on the network. | |
1505 | */ | |
1506 | if(skb->len > 0 && | |
1507 | (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) && | |
1508 | tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) { | |
1509 | if (!pskb_trim(skb, 0)) { | |
1510 | TCP_SKB_CB(skb)->seq = TCP_SKB_CB(skb)->end_seq - 1; | |
1511 | skb_shinfo(skb)->tso_segs = 1; | |
1512 | skb_shinfo(skb)->tso_size = 0; | |
1513 | skb->ip_summed = CHECKSUM_NONE; | |
1514 | skb->csum = 0; | |
1515 | } | |
1516 | } | |
1517 | ||
1518 | /* Make a copy, if the first transmission SKB clone we made | |
1519 | * is still in somebody's hands, else make a clone. | |
1520 | */ | |
1521 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
1da177e4 | 1522 | |
dfb4b9dc | 1523 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
1da177e4 LT |
1524 | |
1525 | if (err == 0) { | |
1526 | /* Update global TCP statistics. */ | |
1527 | TCP_INC_STATS(TCP_MIB_RETRANSSEGS); | |
1528 | ||
1529 | tp->total_retrans++; | |
1530 | ||
1531 | #if FASTRETRANS_DEBUG > 0 | |
1532 | if (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) { | |
1533 | if (net_ratelimit()) | |
1534 | printk(KERN_DEBUG "retrans_out leaked.\n"); | |
1535 | } | |
1536 | #endif | |
1537 | TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; | |
1538 | tp->retrans_out += tcp_skb_pcount(skb); | |
1539 | ||
1540 | /* Save stamp of the first retransmit. */ | |
1541 | if (!tp->retrans_stamp) | |
1542 | tp->retrans_stamp = TCP_SKB_CB(skb)->when; | |
1543 | ||
1544 | tp->undo_retrans++; | |
1545 | ||
1546 | /* snd_nxt is stored to detect loss of retransmitted segment, | |
1547 | * see tcp_input.c tcp_sacktag_write_queue(). | |
1548 | */ | |
1549 | TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; | |
1550 | } | |
1551 | return err; | |
1552 | } | |
1553 | ||
1554 | /* This gets called after a retransmit timeout, and the initially | |
1555 | * retransmitted data is acknowledged. It tries to continue | |
1556 | * resending the rest of the retransmit queue, until either | |
1557 | * we've sent it all or the congestion window limit is reached. | |
1558 | * If doing SACK, the first ACK which comes back for a timeout | |
1559 | * based retransmit packet might feed us FACK information again. | |
1560 | * If so, we use it to avoid unnecessarily retransmissions. | |
1561 | */ | |
1562 | void tcp_xmit_retransmit_queue(struct sock *sk) | |
1563 | { | |
6687e988 | 1564 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
1565 | struct tcp_sock *tp = tcp_sk(sk); |
1566 | struct sk_buff *skb; | |
6a438bbe SH |
1567 | int packet_cnt; |
1568 | ||
1569 | if (tp->retransmit_skb_hint) { | |
1570 | skb = tp->retransmit_skb_hint; | |
1571 | packet_cnt = tp->retransmit_cnt_hint; | |
1572 | }else{ | |
1573 | skb = sk->sk_write_queue.next; | |
1574 | packet_cnt = 0; | |
1575 | } | |
1da177e4 LT |
1576 | |
1577 | /* First pass: retransmit lost packets. */ | |
6a438bbe SH |
1578 | if (tp->lost_out) { |
1579 | sk_stream_for_retrans_queue_from(skb, sk) { | |
1da177e4 LT |
1580 | __u8 sacked = TCP_SKB_CB(skb)->sacked; |
1581 | ||
6a438bbe SH |
1582 | /* we could do better than to assign each time */ |
1583 | tp->retransmit_skb_hint = skb; | |
1584 | tp->retransmit_cnt_hint = packet_cnt; | |
1585 | ||
1da177e4 LT |
1586 | /* Assume this retransmit will generate |
1587 | * only one packet for congestion window | |
1588 | * calculation purposes. This works because | |
1589 | * tcp_retransmit_skb() will chop up the | |
1590 | * packet to be MSS sized and all the | |
1591 | * packet counting works out. | |
1592 | */ | |
1593 | if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) | |
1594 | return; | |
1595 | ||
6a438bbe | 1596 | if (sacked & TCPCB_LOST) { |
1da177e4 | 1597 | if (!(sacked&(TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))) { |
6a438bbe SH |
1598 | if (tcp_retransmit_skb(sk, skb)) { |
1599 | tp->retransmit_skb_hint = NULL; | |
1da177e4 | 1600 | return; |
6a438bbe | 1601 | } |
6687e988 | 1602 | if (icsk->icsk_ca_state != TCP_CA_Loss) |
1da177e4 LT |
1603 | NET_INC_STATS_BH(LINUX_MIB_TCPFASTRETRANS); |
1604 | else | |
1605 | NET_INC_STATS_BH(LINUX_MIB_TCPSLOWSTARTRETRANS); | |
1606 | ||
1607 | if (skb == | |
1608 | skb_peek(&sk->sk_write_queue)) | |
463c84b9 | 1609 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
3f421baa ACM |
1610 | inet_csk(sk)->icsk_rto, |
1611 | TCP_RTO_MAX); | |
1da177e4 LT |
1612 | } |
1613 | ||
6a438bbe SH |
1614 | packet_cnt += tcp_skb_pcount(skb); |
1615 | if (packet_cnt >= tp->lost_out) | |
1da177e4 LT |
1616 | break; |
1617 | } | |
1618 | } | |
1619 | } | |
1620 | ||
1621 | /* OK, demanded retransmission is finished. */ | |
1622 | ||
1623 | /* Forward retransmissions are possible only during Recovery. */ | |
6687e988 | 1624 | if (icsk->icsk_ca_state != TCP_CA_Recovery) |
1da177e4 LT |
1625 | return; |
1626 | ||
1627 | /* No forward retransmissions in Reno are possible. */ | |
1628 | if (!tp->rx_opt.sack_ok) | |
1629 | return; | |
1630 | ||
1631 | /* Yeah, we have to make difficult choice between forward transmission | |
1632 | * and retransmission... Both ways have their merits... | |
1633 | * | |
1634 | * For now we do not retransmit anything, while we have some new | |
1635 | * segments to send. | |
1636 | */ | |
1637 | ||
1638 | if (tcp_may_send_now(sk, tp)) | |
1639 | return; | |
1640 | ||
6a438bbe SH |
1641 | if (tp->forward_skb_hint) { |
1642 | skb = tp->forward_skb_hint; | |
1643 | packet_cnt = tp->forward_cnt_hint; | |
1644 | } else{ | |
1645 | skb = sk->sk_write_queue.next; | |
1646 | packet_cnt = 0; | |
1647 | } | |
1648 | ||
1649 | sk_stream_for_retrans_queue_from(skb, sk) { | |
1650 | tp->forward_cnt_hint = packet_cnt; | |
1651 | tp->forward_skb_hint = skb; | |
1da177e4 | 1652 | |
1da177e4 LT |
1653 | /* Similar to the retransmit loop above we |
1654 | * can pretend that the retransmitted SKB | |
1655 | * we send out here will be composed of one | |
1656 | * real MSS sized packet because tcp_retransmit_skb() | |
1657 | * will fragment it if necessary. | |
1658 | */ | |
1659 | if (++packet_cnt > tp->fackets_out) | |
1660 | break; | |
1661 | ||
1662 | if (tcp_packets_in_flight(tp) >= tp->snd_cwnd) | |
1663 | break; | |
1664 | ||
1665 | if (TCP_SKB_CB(skb)->sacked & TCPCB_TAGBITS) | |
1666 | continue; | |
1667 | ||
1668 | /* Ok, retransmit it. */ | |
6a438bbe SH |
1669 | if (tcp_retransmit_skb(sk, skb)) { |
1670 | tp->forward_skb_hint = NULL; | |
1da177e4 | 1671 | break; |
6a438bbe | 1672 | } |
1da177e4 LT |
1673 | |
1674 | if (skb == skb_peek(&sk->sk_write_queue)) | |
3f421baa ACM |
1675 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
1676 | inet_csk(sk)->icsk_rto, | |
1677 | TCP_RTO_MAX); | |
1da177e4 LT |
1678 | |
1679 | NET_INC_STATS_BH(LINUX_MIB_TCPFORWARDRETRANS); | |
1680 | } | |
1681 | } | |
1682 | ||
1683 | ||
1684 | /* Send a fin. The caller locks the socket for us. This cannot be | |
1685 | * allowed to fail queueing a FIN frame under any circumstances. | |
1686 | */ | |
1687 | void tcp_send_fin(struct sock *sk) | |
1688 | { | |
1689 | struct tcp_sock *tp = tcp_sk(sk); | |
1690 | struct sk_buff *skb = skb_peek_tail(&sk->sk_write_queue); | |
1691 | int mss_now; | |
1692 | ||
1693 | /* Optimization, tack on the FIN if we have a queue of | |
1694 | * unsent frames. But be careful about outgoing SACKS | |
1695 | * and IP options. | |
1696 | */ | |
1697 | mss_now = tcp_current_mss(sk, 1); | |
1698 | ||
1699 | if (sk->sk_send_head != NULL) { | |
1700 | TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_FIN; | |
1701 | TCP_SKB_CB(skb)->end_seq++; | |
1702 | tp->write_seq++; | |
1703 | } else { | |
1704 | /* Socket is locked, keep trying until memory is available. */ | |
1705 | for (;;) { | |
d179cd12 | 1706 | skb = alloc_skb_fclone(MAX_TCP_HEADER, GFP_KERNEL); |
1da177e4 LT |
1707 | if (skb) |
1708 | break; | |
1709 | yield(); | |
1710 | } | |
1711 | ||
1712 | /* Reserve space for headers and prepare control bits. */ | |
1713 | skb_reserve(skb, MAX_TCP_HEADER); | |
1714 | skb->csum = 0; | |
1715 | TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_FIN); | |
1716 | TCP_SKB_CB(skb)->sacked = 0; | |
1717 | skb_shinfo(skb)->tso_segs = 1; | |
1718 | skb_shinfo(skb)->tso_size = 0; | |
1719 | ||
1720 | /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ | |
1721 | TCP_SKB_CB(skb)->seq = tp->write_seq; | |
1722 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1; | |
1723 | tcp_queue_skb(sk, skb); | |
1724 | } | |
1725 | __tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_OFF); | |
1726 | } | |
1727 | ||
1728 | /* We get here when a process closes a file descriptor (either due to | |
1729 | * an explicit close() or as a byproduct of exit()'ing) and there | |
1730 | * was unread data in the receive queue. This behavior is recommended | |
1731 | * by draft-ietf-tcpimpl-prob-03.txt section 3.10. -DaveM | |
1732 | */ | |
dd0fc66f | 1733 | void tcp_send_active_reset(struct sock *sk, gfp_t priority) |
1da177e4 LT |
1734 | { |
1735 | struct tcp_sock *tp = tcp_sk(sk); | |
1736 | struct sk_buff *skb; | |
1737 | ||
1738 | /* NOTE: No TCP options attached and we never retransmit this. */ | |
1739 | skb = alloc_skb(MAX_TCP_HEADER, priority); | |
1740 | if (!skb) { | |
1741 | NET_INC_STATS(LINUX_MIB_TCPABORTFAILED); | |
1742 | return; | |
1743 | } | |
1744 | ||
1745 | /* Reserve space for headers and prepare control bits. */ | |
1746 | skb_reserve(skb, MAX_TCP_HEADER); | |
1747 | skb->csum = 0; | |
1748 | TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_RST); | |
1749 | TCP_SKB_CB(skb)->sacked = 0; | |
1750 | skb_shinfo(skb)->tso_segs = 1; | |
1751 | skb_shinfo(skb)->tso_size = 0; | |
1752 | ||
1753 | /* Send it off. */ | |
1754 | TCP_SKB_CB(skb)->seq = tcp_acceptable_seq(sk, tp); | |
1755 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq; | |
1756 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
dfb4b9dc | 1757 | if (tcp_transmit_skb(sk, skb, 0, priority)) |
1da177e4 LT |
1758 | NET_INC_STATS(LINUX_MIB_TCPABORTFAILED); |
1759 | } | |
1760 | ||
1761 | /* WARNING: This routine must only be called when we have already sent | |
1762 | * a SYN packet that crossed the incoming SYN that caused this routine | |
1763 | * to get called. If this assumption fails then the initial rcv_wnd | |
1764 | * and rcv_wscale values will not be correct. | |
1765 | */ | |
1766 | int tcp_send_synack(struct sock *sk) | |
1767 | { | |
1768 | struct sk_buff* skb; | |
1769 | ||
1770 | skb = skb_peek(&sk->sk_write_queue); | |
1771 | if (skb == NULL || !(TCP_SKB_CB(skb)->flags&TCPCB_FLAG_SYN)) { | |
1772 | printk(KERN_DEBUG "tcp_send_synack: wrong queue state\n"); | |
1773 | return -EFAULT; | |
1774 | } | |
1775 | if (!(TCP_SKB_CB(skb)->flags&TCPCB_FLAG_ACK)) { | |
1776 | if (skb_cloned(skb)) { | |
1777 | struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); | |
1778 | if (nskb == NULL) | |
1779 | return -ENOMEM; | |
1780 | __skb_unlink(skb, &sk->sk_write_queue); | |
1781 | skb_header_release(nskb); | |
1782 | __skb_queue_head(&sk->sk_write_queue, nskb); | |
1783 | sk_stream_free_skb(sk, skb); | |
1784 | sk_charge_skb(sk, nskb); | |
1785 | skb = nskb; | |
1786 | } | |
1787 | ||
1788 | TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_ACK; | |
1789 | TCP_ECN_send_synack(tcp_sk(sk), skb); | |
1790 | } | |
1791 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
dfb4b9dc | 1792 | return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
1da177e4 LT |
1793 | } |
1794 | ||
1795 | /* | |
1796 | * Prepare a SYN-ACK. | |
1797 | */ | |
1798 | struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst, | |
60236fdd | 1799 | struct request_sock *req) |
1da177e4 | 1800 | { |
2e6599cb | 1801 | struct inet_request_sock *ireq = inet_rsk(req); |
1da177e4 LT |
1802 | struct tcp_sock *tp = tcp_sk(sk); |
1803 | struct tcphdr *th; | |
1804 | int tcp_header_size; | |
1805 | struct sk_buff *skb; | |
1806 | ||
1807 | skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15, 1, GFP_ATOMIC); | |
1808 | if (skb == NULL) | |
1809 | return NULL; | |
1810 | ||
1811 | /* Reserve space for headers. */ | |
1812 | skb_reserve(skb, MAX_TCP_HEADER); | |
1813 | ||
1814 | skb->dst = dst_clone(dst); | |
1815 | ||
1816 | tcp_header_size = (sizeof(struct tcphdr) + TCPOLEN_MSS + | |
2e6599cb ACM |
1817 | (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0) + |
1818 | (ireq->wscale_ok ? TCPOLEN_WSCALE_ALIGNED : 0) + | |
1da177e4 | 1819 | /* SACK_PERM is in the place of NOP NOP of TS */ |
2e6599cb | 1820 | ((ireq->sack_ok && !ireq->tstamp_ok) ? TCPOLEN_SACKPERM_ALIGNED : 0)); |
1da177e4 LT |
1821 | skb->h.th = th = (struct tcphdr *) skb_push(skb, tcp_header_size); |
1822 | ||
1823 | memset(th, 0, sizeof(struct tcphdr)); | |
1824 | th->syn = 1; | |
1825 | th->ack = 1; | |
1826 | if (dst->dev->features&NETIF_F_TSO) | |
2e6599cb | 1827 | ireq->ecn_ok = 0; |
1da177e4 LT |
1828 | TCP_ECN_make_synack(req, th); |
1829 | th->source = inet_sk(sk)->sport; | |
2e6599cb ACM |
1830 | th->dest = ireq->rmt_port; |
1831 | TCP_SKB_CB(skb)->seq = tcp_rsk(req)->snt_isn; | |
1da177e4 LT |
1832 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1; |
1833 | TCP_SKB_CB(skb)->sacked = 0; | |
1834 | skb_shinfo(skb)->tso_segs = 1; | |
1835 | skb_shinfo(skb)->tso_size = 0; | |
1836 | th->seq = htonl(TCP_SKB_CB(skb)->seq); | |
2e6599cb | 1837 | th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1); |
1da177e4 LT |
1838 | if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */ |
1839 | __u8 rcv_wscale; | |
1840 | /* Set this up on the first call only */ | |
1841 | req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW); | |
1842 | /* tcp_full_space because it is guaranteed to be the first packet */ | |
1843 | tcp_select_initial_window(tcp_full_space(sk), | |
2e6599cb | 1844 | dst_metric(dst, RTAX_ADVMSS) - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), |
1da177e4 LT |
1845 | &req->rcv_wnd, |
1846 | &req->window_clamp, | |
2e6599cb | 1847 | ireq->wscale_ok, |
1da177e4 | 1848 | &rcv_wscale); |
2e6599cb | 1849 | ireq->rcv_wscale = rcv_wscale; |
1da177e4 LT |
1850 | } |
1851 | ||
1852 | /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ | |
1853 | th->window = htons(req->rcv_wnd); | |
1854 | ||
1855 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
2e6599cb ACM |
1856 | tcp_syn_build_options((__u32 *)(th + 1), dst_metric(dst, RTAX_ADVMSS), ireq->tstamp_ok, |
1857 | ireq->sack_ok, ireq->wscale_ok, ireq->rcv_wscale, | |
1da177e4 LT |
1858 | TCP_SKB_CB(skb)->when, |
1859 | req->ts_recent); | |
1860 | ||
1861 | skb->csum = 0; | |
1862 | th->doff = (tcp_header_size >> 2); | |
1863 | TCP_INC_STATS(TCP_MIB_OUTSEGS); | |
1864 | return skb; | |
1865 | } | |
1866 | ||
1867 | /* | |
1868 | * Do all connect socket setups that can be done AF independent. | |
1869 | */ | |
40efc6fa | 1870 | static void tcp_connect_init(struct sock *sk) |
1da177e4 LT |
1871 | { |
1872 | struct dst_entry *dst = __sk_dst_get(sk); | |
1873 | struct tcp_sock *tp = tcp_sk(sk); | |
1874 | __u8 rcv_wscale; | |
1875 | ||
1876 | /* We'll fix this up when we get a response from the other end. | |
1877 | * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. | |
1878 | */ | |
1879 | tp->tcp_header_len = sizeof(struct tcphdr) + | |
1880 | (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0); | |
1881 | ||
1882 | /* If user gave his TCP_MAXSEG, record it to clamp */ | |
1883 | if (tp->rx_opt.user_mss) | |
1884 | tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; | |
1885 | tp->max_window = 0; | |
1886 | tcp_sync_mss(sk, dst_mtu(dst)); | |
1887 | ||
1888 | if (!tp->window_clamp) | |
1889 | tp->window_clamp = dst_metric(dst, RTAX_WINDOW); | |
1890 | tp->advmss = dst_metric(dst, RTAX_ADVMSS); | |
1891 | tcp_initialize_rcv_mss(sk); | |
1da177e4 LT |
1892 | |
1893 | tcp_select_initial_window(tcp_full_space(sk), | |
1894 | tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), | |
1895 | &tp->rcv_wnd, | |
1896 | &tp->window_clamp, | |
1897 | sysctl_tcp_window_scaling, | |
1898 | &rcv_wscale); | |
1899 | ||
1900 | tp->rx_opt.rcv_wscale = rcv_wscale; | |
1901 | tp->rcv_ssthresh = tp->rcv_wnd; | |
1902 | ||
1903 | sk->sk_err = 0; | |
1904 | sock_reset_flag(sk, SOCK_DONE); | |
1905 | tp->snd_wnd = 0; | |
1906 | tcp_init_wl(tp, tp->write_seq, 0); | |
1907 | tp->snd_una = tp->write_seq; | |
1908 | tp->snd_sml = tp->write_seq; | |
1909 | tp->rcv_nxt = 0; | |
1910 | tp->rcv_wup = 0; | |
1911 | tp->copied_seq = 0; | |
1912 | ||
463c84b9 ACM |
1913 | inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT; |
1914 | inet_csk(sk)->icsk_retransmits = 0; | |
1da177e4 LT |
1915 | tcp_clear_retrans(tp); |
1916 | } | |
1917 | ||
1918 | /* | |
1919 | * Build a SYN and send it off. | |
1920 | */ | |
1921 | int tcp_connect(struct sock *sk) | |
1922 | { | |
1923 | struct tcp_sock *tp = tcp_sk(sk); | |
1924 | struct sk_buff *buff; | |
1925 | ||
1926 | tcp_connect_init(sk); | |
1927 | ||
d179cd12 | 1928 | buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation); |
1da177e4 LT |
1929 | if (unlikely(buff == NULL)) |
1930 | return -ENOBUFS; | |
1931 | ||
1932 | /* Reserve space for headers. */ | |
1933 | skb_reserve(buff, MAX_TCP_HEADER); | |
1934 | ||
1935 | TCP_SKB_CB(buff)->flags = TCPCB_FLAG_SYN; | |
1936 | TCP_ECN_send_syn(sk, tp, buff); | |
1937 | TCP_SKB_CB(buff)->sacked = 0; | |
1938 | skb_shinfo(buff)->tso_segs = 1; | |
1939 | skb_shinfo(buff)->tso_size = 0; | |
1940 | buff->csum = 0; | |
1941 | TCP_SKB_CB(buff)->seq = tp->write_seq++; | |
1942 | TCP_SKB_CB(buff)->end_seq = tp->write_seq; | |
1943 | tp->snd_nxt = tp->write_seq; | |
1944 | tp->pushed_seq = tp->write_seq; | |
1da177e4 LT |
1945 | |
1946 | /* Send it off. */ | |
1947 | TCP_SKB_CB(buff)->when = tcp_time_stamp; | |
1948 | tp->retrans_stamp = TCP_SKB_CB(buff)->when; | |
1949 | skb_header_release(buff); | |
1950 | __skb_queue_tail(&sk->sk_write_queue, buff); | |
1951 | sk_charge_skb(sk, buff); | |
1952 | tp->packets_out += tcp_skb_pcount(buff); | |
dfb4b9dc | 1953 | tcp_transmit_skb(sk, buff, 1, GFP_KERNEL); |
1da177e4 LT |
1954 | TCP_INC_STATS(TCP_MIB_ACTIVEOPENS); |
1955 | ||
1956 | /* Timer for repeating the SYN until an answer. */ | |
3f421baa ACM |
1957 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
1958 | inet_csk(sk)->icsk_rto, TCP_RTO_MAX); | |
1da177e4 LT |
1959 | return 0; |
1960 | } | |
1961 | ||
1962 | /* Send out a delayed ack, the caller does the policy checking | |
1963 | * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() | |
1964 | * for details. | |
1965 | */ | |
1966 | void tcp_send_delayed_ack(struct sock *sk) | |
1967 | { | |
463c84b9 ACM |
1968 | struct inet_connection_sock *icsk = inet_csk(sk); |
1969 | int ato = icsk->icsk_ack.ato; | |
1da177e4 LT |
1970 | unsigned long timeout; |
1971 | ||
1972 | if (ato > TCP_DELACK_MIN) { | |
463c84b9 | 1973 | const struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
1974 | int max_ato = HZ/2; |
1975 | ||
463c84b9 | 1976 | if (icsk->icsk_ack.pingpong || (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) |
1da177e4 LT |
1977 | max_ato = TCP_DELACK_MAX; |
1978 | ||
1979 | /* Slow path, intersegment interval is "high". */ | |
1980 | ||
1981 | /* If some rtt estimate is known, use it to bound delayed ack. | |
463c84b9 | 1982 | * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements |
1da177e4 LT |
1983 | * directly. |
1984 | */ | |
1985 | if (tp->srtt) { | |
1986 | int rtt = max(tp->srtt>>3, TCP_DELACK_MIN); | |
1987 | ||
1988 | if (rtt < max_ato) | |
1989 | max_ato = rtt; | |
1990 | } | |
1991 | ||
1992 | ato = min(ato, max_ato); | |
1993 | } | |
1994 | ||
1995 | /* Stay within the limit we were given */ | |
1996 | timeout = jiffies + ato; | |
1997 | ||
1998 | /* Use new timeout only if there wasn't a older one earlier. */ | |
463c84b9 | 1999 | if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { |
1da177e4 LT |
2000 | /* If delack timer was blocked or is about to expire, |
2001 | * send ACK now. | |
2002 | */ | |
463c84b9 ACM |
2003 | if (icsk->icsk_ack.blocked || |
2004 | time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { | |
1da177e4 LT |
2005 | tcp_send_ack(sk); |
2006 | return; | |
2007 | } | |
2008 | ||
463c84b9 ACM |
2009 | if (!time_before(timeout, icsk->icsk_ack.timeout)) |
2010 | timeout = icsk->icsk_ack.timeout; | |
1da177e4 | 2011 | } |
463c84b9 ACM |
2012 | icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; |
2013 | icsk->icsk_ack.timeout = timeout; | |
2014 | sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); | |
1da177e4 LT |
2015 | } |
2016 | ||
2017 | /* This routine sends an ack and also updates the window. */ | |
2018 | void tcp_send_ack(struct sock *sk) | |
2019 | { | |
2020 | /* If we have been reset, we may not send again. */ | |
2021 | if (sk->sk_state != TCP_CLOSE) { | |
2022 | struct tcp_sock *tp = tcp_sk(sk); | |
2023 | struct sk_buff *buff; | |
2024 | ||
2025 | /* We are not putting this on the write queue, so | |
2026 | * tcp_transmit_skb() will set the ownership to this | |
2027 | * sock. | |
2028 | */ | |
2029 | buff = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); | |
2030 | if (buff == NULL) { | |
463c84b9 ACM |
2031 | inet_csk_schedule_ack(sk); |
2032 | inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; | |
3f421baa ACM |
2033 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, |
2034 | TCP_DELACK_MAX, TCP_RTO_MAX); | |
1da177e4 LT |
2035 | return; |
2036 | } | |
2037 | ||
2038 | /* Reserve space for headers and prepare control bits. */ | |
2039 | skb_reserve(buff, MAX_TCP_HEADER); | |
2040 | buff->csum = 0; | |
2041 | TCP_SKB_CB(buff)->flags = TCPCB_FLAG_ACK; | |
2042 | TCP_SKB_CB(buff)->sacked = 0; | |
2043 | skb_shinfo(buff)->tso_segs = 1; | |
2044 | skb_shinfo(buff)->tso_size = 0; | |
2045 | ||
2046 | /* Send it off, this clears delayed acks for us. */ | |
2047 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(buff)->end_seq = tcp_acceptable_seq(sk, tp); | |
2048 | TCP_SKB_CB(buff)->when = tcp_time_stamp; | |
dfb4b9dc | 2049 | tcp_transmit_skb(sk, buff, 0, GFP_ATOMIC); |
1da177e4 LT |
2050 | } |
2051 | } | |
2052 | ||
2053 | /* This routine sends a packet with an out of date sequence | |
2054 | * number. It assumes the other end will try to ack it. | |
2055 | * | |
2056 | * Question: what should we make while urgent mode? | |
2057 | * 4.4BSD forces sending single byte of data. We cannot send | |
2058 | * out of window data, because we have SND.NXT==SND.MAX... | |
2059 | * | |
2060 | * Current solution: to send TWO zero-length segments in urgent mode: | |
2061 | * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is | |
2062 | * out-of-date with SND.UNA-1 to probe window. | |
2063 | */ | |
2064 | static int tcp_xmit_probe_skb(struct sock *sk, int urgent) | |
2065 | { | |
2066 | struct tcp_sock *tp = tcp_sk(sk); | |
2067 | struct sk_buff *skb; | |
2068 | ||
2069 | /* We don't queue it, tcp_transmit_skb() sets ownership. */ | |
2070 | skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); | |
2071 | if (skb == NULL) | |
2072 | return -1; | |
2073 | ||
2074 | /* Reserve space for headers and set control bits. */ | |
2075 | skb_reserve(skb, MAX_TCP_HEADER); | |
2076 | skb->csum = 0; | |
2077 | TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK; | |
2078 | TCP_SKB_CB(skb)->sacked = urgent; | |
2079 | skb_shinfo(skb)->tso_segs = 1; | |
2080 | skb_shinfo(skb)->tso_size = 0; | |
2081 | ||
2082 | /* Use a previous sequence. This should cause the other | |
2083 | * end to send an ack. Don't queue or clone SKB, just | |
2084 | * send it. | |
2085 | */ | |
2086 | TCP_SKB_CB(skb)->seq = urgent ? tp->snd_una : tp->snd_una - 1; | |
2087 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq; | |
2088 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
dfb4b9dc | 2089 | return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC); |
1da177e4 LT |
2090 | } |
2091 | ||
2092 | int tcp_write_wakeup(struct sock *sk) | |
2093 | { | |
2094 | if (sk->sk_state != TCP_CLOSE) { | |
2095 | struct tcp_sock *tp = tcp_sk(sk); | |
2096 | struct sk_buff *skb; | |
2097 | ||
2098 | if ((skb = sk->sk_send_head) != NULL && | |
2099 | before(TCP_SKB_CB(skb)->seq, tp->snd_una+tp->snd_wnd)) { | |
2100 | int err; | |
2101 | unsigned int mss = tcp_current_mss(sk, 0); | |
2102 | unsigned int seg_size = tp->snd_una+tp->snd_wnd-TCP_SKB_CB(skb)->seq; | |
2103 | ||
2104 | if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) | |
2105 | tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; | |
2106 | ||
2107 | /* We are probing the opening of a window | |
2108 | * but the window size is != 0 | |
2109 | * must have been a result SWS avoidance ( sender ) | |
2110 | */ | |
2111 | if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || | |
2112 | skb->len > mss) { | |
2113 | seg_size = min(seg_size, mss); | |
2114 | TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; | |
846998ae | 2115 | if (tcp_fragment(sk, skb, seg_size, mss)) |
1da177e4 | 2116 | return -1; |
1da177e4 | 2117 | } else if (!tcp_skb_pcount(skb)) |
846998ae | 2118 | tcp_set_skb_tso_segs(sk, skb, mss); |
1da177e4 LT |
2119 | |
2120 | TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; | |
2121 | TCP_SKB_CB(skb)->when = tcp_time_stamp; | |
dfb4b9dc | 2122 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
1da177e4 LT |
2123 | if (!err) { |
2124 | update_send_head(sk, tp, skb); | |
2125 | } | |
2126 | return err; | |
2127 | } else { | |
2128 | if (tp->urg_mode && | |
2129 | between(tp->snd_up, tp->snd_una+1, tp->snd_una+0xFFFF)) | |
2130 | tcp_xmit_probe_skb(sk, TCPCB_URG); | |
2131 | return tcp_xmit_probe_skb(sk, 0); | |
2132 | } | |
2133 | } | |
2134 | return -1; | |
2135 | } | |
2136 | ||
2137 | /* A window probe timeout has occurred. If window is not closed send | |
2138 | * a partial packet else a zero probe. | |
2139 | */ | |
2140 | void tcp_send_probe0(struct sock *sk) | |
2141 | { | |
463c84b9 | 2142 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 LT |
2143 | struct tcp_sock *tp = tcp_sk(sk); |
2144 | int err; | |
2145 | ||
2146 | err = tcp_write_wakeup(sk); | |
2147 | ||
2148 | if (tp->packets_out || !sk->sk_send_head) { | |
2149 | /* Cancel probe timer, if it is not required. */ | |
6687e988 | 2150 | icsk->icsk_probes_out = 0; |
463c84b9 | 2151 | icsk->icsk_backoff = 0; |
1da177e4 LT |
2152 | return; |
2153 | } | |
2154 | ||
2155 | if (err <= 0) { | |
463c84b9 ACM |
2156 | if (icsk->icsk_backoff < sysctl_tcp_retries2) |
2157 | icsk->icsk_backoff++; | |
6687e988 | 2158 | icsk->icsk_probes_out++; |
463c84b9 | 2159 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
3f421baa ACM |
2160 | min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX), |
2161 | TCP_RTO_MAX); | |
1da177e4 LT |
2162 | } else { |
2163 | /* If packet was not sent due to local congestion, | |
6687e988 | 2164 | * do not backoff and do not remember icsk_probes_out. |
1da177e4 LT |
2165 | * Let local senders to fight for local resources. |
2166 | * | |
2167 | * Use accumulated backoff yet. | |
2168 | */ | |
6687e988 ACM |
2169 | if (!icsk->icsk_probes_out) |
2170 | icsk->icsk_probes_out = 1; | |
463c84b9 ACM |
2171 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, |
2172 | min(icsk->icsk_rto << icsk->icsk_backoff, | |
3f421baa ACM |
2173 | TCP_RESOURCE_PROBE_INTERVAL), |
2174 | TCP_RTO_MAX); | |
1da177e4 LT |
2175 | } |
2176 | } | |
2177 | ||
2178 | EXPORT_SYMBOL(tcp_connect); | |
2179 | EXPORT_SYMBOL(tcp_make_synack); | |
2180 | EXPORT_SYMBOL(tcp_simple_retransmit); | |
2181 | EXPORT_SYMBOL(tcp_sync_mss); | |
f4805ede | 2182 | EXPORT_SYMBOL(sysctl_tcp_tso_win_divisor); |