Commit | Line | Data |
---|---|---|
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 | * | |
02c30a84 | 8 | * Authors: Ross Biro |
1da177e4 LT |
9 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
10 | * Mark Evans, <evansmp@uhura.aston.ac.uk> | |
11 | * Corey Minyard <wf-rch!minyard@relay.EU.net> | |
12 | * Florian La Roche, <flla@stud.uni-sb.de> | |
13 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> | |
14 | * Linus Torvalds, <torvalds@cs.helsinki.fi> | |
15 | * Alan Cox, <gw4pts@gw4pts.ampr.org> | |
16 | * Matthew Dillon, <dillon@apollo.west.oic.com> | |
17 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> | |
18 | * Jorge Cwik, <jorge@laser.satlink.net> | |
19 | */ | |
20 | ||
21 | /* | |
22 | * Changes: Pedro Roque : Retransmit queue handled by TCP. | |
23 | * : Fragmentation on mtu decrease | |
24 | * : Segment collapse on retransmit | |
25 | * : AF independence | |
26 | * | |
27 | * Linus Torvalds : send_delayed_ack | |
28 | * David S. Miller : Charge memory using the right skb | |
29 | * during syn/ack processing. | |
30 | * David S. Miller : Output engine completely rewritten. | |
31 | * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. | |
32 | * Cacophonix Gaul : draft-minshall-nagle-01 | |
33 | * J Hadi Salim : ECN support | |
34 | * | |
35 | */ | |
36 | ||
37 | #include <net/tcp.h> | |
38 | ||
39 | #include <linux/compiler.h> | |
40 | #include <linux/module.h> | |
1da177e4 LT |
41 | |
42 | /* People can turn this off for buggy TCP's found in printers etc. */ | |
ab32ea5d | 43 | int sysctl_tcp_retrans_collapse __read_mostly = 1; |
1da177e4 | 44 | |
09cb105e | 45 | /* People can turn this on to work with those rare, broken TCPs that |
15d99e02 RJ |
46 | * interpret the window field as a signed quantity. |
47 | */ | |
ab32ea5d | 48 | int sysctl_tcp_workaround_signed_windows __read_mostly = 0; |
15d99e02 | 49 | |
1da177e4 LT |
50 | /* This limits the percentage of the congestion window which we |
51 | * will allow a single TSO frame to consume. Building TSO frames | |
52 | * which are too large can cause TCP streams to be bursty. | |
53 | */ | |
ab32ea5d | 54 | int sysctl_tcp_tso_win_divisor __read_mostly = 3; |
1da177e4 | 55 | |
ab32ea5d BH |
56 | int sysctl_tcp_mtu_probing __read_mostly = 0; |
57 | int sysctl_tcp_base_mss __read_mostly = 512; | |
5d424d5a | 58 | |
35089bb2 | 59 | /* By default, RFC2861 behavior. */ |
ab32ea5d | 60 | int sysctl_tcp_slow_start_after_idle __read_mostly = 1; |
35089bb2 | 61 | |
519855c5 | 62 | int sysctl_tcp_cookie_size __read_mostly = 0; /* TCP_COOKIE_MAX */ |
e6b09cca | 63 | EXPORT_SYMBOL_GPL(sysctl_tcp_cookie_size); |
519855c5 WAS |
64 | |
65 | ||
67edfef7 | 66 | /* Account for new data that has been sent to the network. */ |
66f5fe62 | 67 | static void tcp_event_new_data_sent(struct sock *sk, struct sk_buff *skb) |
1da177e4 | 68 | { |
9e412ba7 | 69 | struct tcp_sock *tp = tcp_sk(sk); |
66f5fe62 | 70 | unsigned int prior_packets = tp->packets_out; |
9e412ba7 | 71 | |
fe067e8a | 72 | tcp_advance_send_head(sk, skb); |
1da177e4 | 73 | tp->snd_nxt = TCP_SKB_CB(skb)->end_seq; |
8512430e IJ |
74 | |
75 | /* Don't override Nagle indefinately with F-RTO */ | |
76 | if (tp->frto_counter == 2) | |
77 | tp->frto_counter = 3; | |
66f5fe62 IJ |
78 | |
79 | tp->packets_out += tcp_skb_pcount(skb); | |
80 | if (!prior_packets) | |
81 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
82 | inet_csk(sk)->icsk_rto, TCP_RTO_MAX); | |
1da177e4 LT |
83 | } |
84 | ||
85 | /* SND.NXT, if window was not shrunk. | |
86 | * If window has been shrunk, what should we make? It is not clear at all. | |
87 | * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( | |
88 | * Anything in between SND.UNA...SND.UNA+SND.WND also can be already | |
89 | * invalid. OK, let's make this for now: | |
90 | */ | |
9e412ba7 | 91 | static inline __u32 tcp_acceptable_seq(struct sock *sk) |
1da177e4 | 92 | { |
9e412ba7 IJ |
93 | struct tcp_sock *tp = tcp_sk(sk); |
94 | ||
90840def | 95 | if (!before(tcp_wnd_end(tp), tp->snd_nxt)) |
1da177e4 LT |
96 | return tp->snd_nxt; |
97 | else | |
90840def | 98 | return tcp_wnd_end(tp); |
1da177e4 LT |
99 | } |
100 | ||
101 | /* Calculate mss to advertise in SYN segment. | |
102 | * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: | |
103 | * | |
104 | * 1. It is independent of path mtu. | |
105 | * 2. Ideally, it is maximal possible segment size i.e. 65535-40. | |
106 | * 3. For IPv4 it is reasonable to calculate it from maximal MTU of | |
107 | * attached devices, because some buggy hosts are confused by | |
108 | * large MSS. | |
109 | * 4. We do not make 3, we advertise MSS, calculated from first | |
110 | * hop device mtu, but allow to raise it to ip_rt_min_advmss. | |
111 | * This may be overridden via information stored in routing table. | |
112 | * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, | |
113 | * probably even Jumbo". | |
114 | */ | |
115 | static __u16 tcp_advertise_mss(struct sock *sk) | |
116 | { | |
117 | struct tcp_sock *tp = tcp_sk(sk); | |
118 | struct dst_entry *dst = __sk_dst_get(sk); | |
119 | int mss = tp->advmss; | |
120 | ||
121 | if (dst && dst_metric(dst, RTAX_ADVMSS) < mss) { | |
122 | mss = dst_metric(dst, RTAX_ADVMSS); | |
123 | tp->advmss = mss; | |
124 | } | |
125 | ||
126 | return (__u16)mss; | |
127 | } | |
128 | ||
129 | /* RFC2861. Reset CWND after idle period longer RTO to "restart window". | |
130 | * This is the first part of cwnd validation mechanism. */ | |
463c84b9 | 131 | static void tcp_cwnd_restart(struct sock *sk, struct dst_entry *dst) |
1da177e4 | 132 | { |
463c84b9 | 133 | struct tcp_sock *tp = tcp_sk(sk); |
1da177e4 LT |
134 | s32 delta = tcp_time_stamp - tp->lsndtime; |
135 | u32 restart_cwnd = tcp_init_cwnd(tp, dst); | |
136 | u32 cwnd = tp->snd_cwnd; | |
137 | ||
6687e988 | 138 | tcp_ca_event(sk, CA_EVENT_CWND_RESTART); |
1da177e4 | 139 | |
6687e988 | 140 | tp->snd_ssthresh = tcp_current_ssthresh(sk); |
1da177e4 LT |
141 | restart_cwnd = min(restart_cwnd, cwnd); |
142 | ||
463c84b9 | 143 | while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) |
1da177e4 LT |
144 | cwnd >>= 1; |
145 | tp->snd_cwnd = max(cwnd, restart_cwnd); | |
146 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
147 | tp->snd_cwnd_used = 0; | |
148 | } | |
149 | ||
67edfef7 | 150 | /* Congestion state accounting after a packet has been sent. */ |
40efc6fa SH |
151 | static void tcp_event_data_sent(struct tcp_sock *tp, |
152 | struct sk_buff *skb, struct sock *sk) | |
1da177e4 | 153 | { |
463c84b9 ACM |
154 | struct inet_connection_sock *icsk = inet_csk(sk); |
155 | const u32 now = tcp_time_stamp; | |
1da177e4 | 156 | |
35089bb2 DM |
157 | if (sysctl_tcp_slow_start_after_idle && |
158 | (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto)) | |
463c84b9 | 159 | tcp_cwnd_restart(sk, __sk_dst_get(sk)); |
1da177e4 LT |
160 | |
161 | tp->lsndtime = now; | |
162 | ||
163 | /* If it is a reply for ato after last received | |
164 | * packet, enter pingpong mode. | |
165 | */ | |
463c84b9 ACM |
166 | if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) |
167 | icsk->icsk_ack.pingpong = 1; | |
1da177e4 LT |
168 | } |
169 | ||
67edfef7 | 170 | /* Account for an ACK we sent. */ |
40efc6fa | 171 | static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts) |
1da177e4 | 172 | { |
463c84b9 ACM |
173 | tcp_dec_quickack_mode(sk, pkts); |
174 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); | |
1da177e4 LT |
175 | } |
176 | ||
177 | /* Determine a window scaling and initial window to offer. | |
178 | * Based on the assumption that the given amount of space | |
179 | * will be offered. Store the results in the tp structure. | |
180 | * NOTE: for smooth operation initial space offering should | |
181 | * be a multiple of mss if possible. We assume here that mss >= 1. | |
182 | * This MUST be enforced by all callers. | |
183 | */ | |
184 | void tcp_select_initial_window(int __space, __u32 mss, | |
185 | __u32 *rcv_wnd, __u32 *window_clamp, | |
186 | int wscale_ok, __u8 *rcv_wscale) | |
187 | { | |
188 | unsigned int space = (__space < 0 ? 0 : __space); | |
189 | ||
190 | /* If no clamp set the clamp to the max possible scaled window */ | |
191 | if (*window_clamp == 0) | |
192 | (*window_clamp) = (65535 << 14); | |
193 | space = min(*window_clamp, space); | |
194 | ||
195 | /* Quantize space offering to a multiple of mss if possible. */ | |
196 | if (space > mss) | |
197 | space = (space / mss) * mss; | |
198 | ||
199 | /* NOTE: offering an initial window larger than 32767 | |
15d99e02 RJ |
200 | * will break some buggy TCP stacks. If the admin tells us |
201 | * it is likely we could be speaking with such a buggy stack | |
202 | * we will truncate our initial window offering to 32K-1 | |
203 | * unless the remote has sent us a window scaling option, | |
204 | * which we interpret as a sign the remote TCP is not | |
205 | * misinterpreting the window field as a signed quantity. | |
1da177e4 | 206 | */ |
15d99e02 RJ |
207 | if (sysctl_tcp_workaround_signed_windows) |
208 | (*rcv_wnd) = min(space, MAX_TCP_WINDOW); | |
209 | else | |
210 | (*rcv_wnd) = space; | |
211 | ||
1da177e4 LT |
212 | (*rcv_wscale) = 0; |
213 | if (wscale_ok) { | |
214 | /* Set window scaling on max possible window | |
e905a9ed | 215 | * See RFC1323 for an explanation of the limit to 14 |
1da177e4 LT |
216 | */ |
217 | space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max); | |
316c1592 | 218 | space = min_t(u32, space, *window_clamp); |
1da177e4 LT |
219 | while (space > 65535 && (*rcv_wscale) < 14) { |
220 | space >>= 1; | |
221 | (*rcv_wscale)++; | |
222 | } | |
223 | } | |
224 | ||
225 | /* Set initial window to value enough for senders, | |
6b251858 | 226 | * following RFC2414. Senders, not following this RFC, |
1da177e4 LT |
227 | * will be satisfied with 2. |
228 | */ | |
056834d9 | 229 | if (mss > (1 << *rcv_wscale)) { |
01ff367e | 230 | int init_cwnd = 4; |
056834d9 | 231 | if (mss > 1460 * 3) |
1da177e4 | 232 | init_cwnd = 2; |
01ff367e DM |
233 | else if (mss > 1460) |
234 | init_cwnd = 3; | |
056834d9 IJ |
235 | if (*rcv_wnd > init_cwnd * mss) |
236 | *rcv_wnd = init_cwnd * mss; | |
1da177e4 LT |
237 | } |
238 | ||
239 | /* Set the clamp no higher than max representable value */ | |
240 | (*window_clamp) = min(65535U << (*rcv_wscale), *window_clamp); | |
241 | } | |
242 | ||
243 | /* Chose a new window to advertise, update state in tcp_sock for the | |
244 | * socket, and return result with RFC1323 scaling applied. The return | |
245 | * value can be stuffed directly into th->window for an outgoing | |
246 | * frame. | |
247 | */ | |
40efc6fa | 248 | static u16 tcp_select_window(struct sock *sk) |
1da177e4 LT |
249 | { |
250 | struct tcp_sock *tp = tcp_sk(sk); | |
251 | u32 cur_win = tcp_receive_window(tp); | |
252 | u32 new_win = __tcp_select_window(sk); | |
253 | ||
254 | /* Never shrink the offered window */ | |
2de979bd | 255 | if (new_win < cur_win) { |
1da177e4 LT |
256 | /* Danger Will Robinson! |
257 | * Don't update rcv_wup/rcv_wnd here or else | |
258 | * we will not be able to advertise a zero | |
259 | * window in time. --DaveM | |
260 | * | |
261 | * Relax Will Robinson. | |
262 | */ | |
607bfbf2 | 263 | new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); |
1da177e4 LT |
264 | } |
265 | tp->rcv_wnd = new_win; | |
266 | tp->rcv_wup = tp->rcv_nxt; | |
267 | ||
268 | /* Make sure we do not exceed the maximum possible | |
269 | * scaled window. | |
270 | */ | |
15d99e02 | 271 | if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows) |
1da177e4 LT |
272 | new_win = min(new_win, MAX_TCP_WINDOW); |
273 | else | |
274 | new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); | |
275 | ||
276 | /* RFC1323 scaling applied */ | |
277 | new_win >>= tp->rx_opt.rcv_wscale; | |
278 | ||
279 | /* If we advertise zero window, disable fast path. */ | |
280 | if (new_win == 0) | |
281 | tp->pred_flags = 0; | |
282 | ||
283 | return new_win; | |
284 | } | |
285 | ||
67edfef7 | 286 | /* Packet ECN state for a SYN-ACK */ |
056834d9 | 287 | static inline void TCP_ECN_send_synack(struct tcp_sock *tp, struct sk_buff *skb) |
bdf1ee5d IJ |
288 | { |
289 | TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_CWR; | |
056834d9 | 290 | if (!(tp->ecn_flags & TCP_ECN_OK)) |
bdf1ee5d IJ |
291 | TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_ECE; |
292 | } | |
293 | ||
67edfef7 | 294 | /* Packet ECN state for a SYN. */ |
bdf1ee5d IJ |
295 | static inline void TCP_ECN_send_syn(struct sock *sk, struct sk_buff *skb) |
296 | { | |
297 | struct tcp_sock *tp = tcp_sk(sk); | |
298 | ||
299 | tp->ecn_flags = 0; | |
255cac91 | 300 | if (sysctl_tcp_ecn == 1) { |
056834d9 | 301 | TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_ECE | TCPCB_FLAG_CWR; |
bdf1ee5d IJ |
302 | tp->ecn_flags = TCP_ECN_OK; |
303 | } | |
304 | } | |
305 | ||
306 | static __inline__ void | |
307 | TCP_ECN_make_synack(struct request_sock *req, struct tcphdr *th) | |
308 | { | |
309 | if (inet_rsk(req)->ecn_ok) | |
310 | th->ece = 1; | |
311 | } | |
312 | ||
67edfef7 AK |
313 | /* Set up ECN state for a packet on a ESTABLISHED socket that is about to |
314 | * be sent. | |
315 | */ | |
bdf1ee5d IJ |
316 | static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb, |
317 | int tcp_header_len) | |
318 | { | |
319 | struct tcp_sock *tp = tcp_sk(sk); | |
320 | ||
321 | if (tp->ecn_flags & TCP_ECN_OK) { | |
322 | /* Not-retransmitted data segment: set ECT and inject CWR. */ | |
323 | if (skb->len != tcp_header_len && | |
324 | !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { | |
325 | INET_ECN_xmit(sk); | |
056834d9 | 326 | if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { |
bdf1ee5d IJ |
327 | tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; |
328 | tcp_hdr(skb)->cwr = 1; | |
329 | skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; | |
330 | } | |
331 | } else { | |
332 | /* ACK or retransmitted segment: clear ECT|CE */ | |
333 | INET_ECN_dontxmit(sk); | |
334 | } | |
335 | if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) | |
336 | tcp_hdr(skb)->ece = 1; | |
337 | } | |
338 | } | |
339 | ||
e870a8ef IJ |
340 | /* Constructs common control bits of non-data skb. If SYN/FIN is present, |
341 | * auto increment end seqno. | |
342 | */ | |
343 | static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) | |
344 | { | |
345 | skb->csum = 0; | |
346 | ||
347 | TCP_SKB_CB(skb)->flags = flags; | |
348 | TCP_SKB_CB(skb)->sacked = 0; | |
349 | ||
350 | skb_shinfo(skb)->gso_segs = 1; | |
351 | skb_shinfo(skb)->gso_size = 0; | |
352 | skb_shinfo(skb)->gso_type = 0; | |
353 | ||
354 | TCP_SKB_CB(skb)->seq = seq; | |
355 | if (flags & (TCPCB_FLAG_SYN | TCPCB_FLAG_FIN)) | |
356 | seq++; | |
357 | TCP_SKB_CB(skb)->end_seq = seq; | |
358 | } | |
359 | ||
33f5f57e IJ |
360 | static inline int tcp_urg_mode(const struct tcp_sock *tp) |
361 | { | |
362 | return tp->snd_una != tp->snd_up; | |
363 | } | |
364 | ||
33ad798c AL |
365 | #define OPTION_SACK_ADVERTISE (1 << 0) |
366 | #define OPTION_TS (1 << 1) | |
367 | #define OPTION_MD5 (1 << 2) | |
89e95a61 | 368 | #define OPTION_WSCALE (1 << 3) |
bd0388ae | 369 | #define OPTION_COOKIE_EXTENSION (1 << 4) |
33ad798c AL |
370 | |
371 | struct tcp_out_options { | |
372 | u8 options; /* bit field of OPTION_* */ | |
373 | u8 ws; /* window scale, 0 to disable */ | |
374 | u8 num_sack_blocks; /* number of SACK blocks to include */ | |
bd0388ae | 375 | u8 hash_size; /* bytes in hash_location */ |
33ad798c AL |
376 | u16 mss; /* 0 to disable */ |
377 | __u32 tsval, tsecr; /* need to include OPTION_TS */ | |
bd0388ae | 378 | __u8 *hash_location; /* temporary pointer, overloaded */ |
33ad798c AL |
379 | }; |
380 | ||
bd0388ae WAS |
381 | /* The sysctl int routines are generic, so check consistency here. |
382 | */ | |
383 | static u8 tcp_cookie_size_check(u8 desired) | |
384 | { | |
385 | if (desired > 0) { | |
386 | /* previously specified */ | |
387 | return desired; | |
388 | } | |
389 | if (sysctl_tcp_cookie_size <= 0) { | |
390 | /* no default specified */ | |
391 | return 0; | |
392 | } | |
393 | if (sysctl_tcp_cookie_size <= TCP_COOKIE_MIN) { | |
394 | /* value too small, specify minimum */ | |
395 | return TCP_COOKIE_MIN; | |
396 | } | |
397 | if (sysctl_tcp_cookie_size >= TCP_COOKIE_MAX) { | |
398 | /* value too large, specify maximum */ | |
399 | return TCP_COOKIE_MAX; | |
400 | } | |
401 | if (0x1 & sysctl_tcp_cookie_size) { | |
402 | /* 8-bit multiple, illegal, fix it */ | |
403 | return (u8)(sysctl_tcp_cookie_size + 0x1); | |
404 | } | |
405 | return (u8)sysctl_tcp_cookie_size; | |
406 | } | |
407 | ||
67edfef7 AK |
408 | /* Write previously computed TCP options to the packet. |
409 | * | |
410 | * Beware: Something in the Internet is very sensitive to the ordering of | |
fd6149d3 IJ |
411 | * TCP options, we learned this through the hard way, so be careful here. |
412 | * Luckily we can at least blame others for their non-compliance but from | |
413 | * inter-operatibility perspective it seems that we're somewhat stuck with | |
414 | * the ordering which we have been using if we want to keep working with | |
415 | * those broken things (not that it currently hurts anybody as there isn't | |
416 | * particular reason why the ordering would need to be changed). | |
417 | * | |
418 | * At least SACK_PERM as the first option is known to lead to a disaster | |
419 | * (but it may well be that other scenarios fail similarly). | |
420 | */ | |
33ad798c | 421 | static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp, |
bd0388ae WAS |
422 | struct tcp_out_options *opts) |
423 | { | |
424 | u8 options = opts->options; /* mungable copy */ | |
425 | ||
426 | /* Having both authentication and cookies for security is redundant, | |
427 | * and there's certainly not enough room. Instead, the cookie-less | |
428 | * extension variant is proposed. | |
429 | * | |
430 | * Consider the pessimal case with authentication. The options | |
431 | * could look like: | |
432 | * COOKIE|MD5(20) + MSS(4) + SACK|TS(12) + WSCALE(4) == 40 | |
433 | */ | |
434 | if (unlikely(OPTION_MD5 & options)) { | |
435 | if (unlikely(OPTION_COOKIE_EXTENSION & options)) { | |
436 | *ptr++ = htonl((TCPOPT_COOKIE << 24) | | |
437 | (TCPOLEN_COOKIE_BASE << 16) | | |
438 | (TCPOPT_MD5SIG << 8) | | |
439 | TCPOLEN_MD5SIG); | |
440 | } else { | |
441 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
442 | (TCPOPT_NOP << 16) | | |
443 | (TCPOPT_MD5SIG << 8) | | |
444 | TCPOLEN_MD5SIG); | |
445 | } | |
446 | options &= ~OPTION_COOKIE_EXTENSION; | |
447 | /* overload cookie hash location */ | |
448 | opts->hash_location = (__u8 *)ptr; | |
33ad798c | 449 | ptr += 4; |
40efc6fa | 450 | } |
33ad798c | 451 | |
fd6149d3 IJ |
452 | if (unlikely(opts->mss)) { |
453 | *ptr++ = htonl((TCPOPT_MSS << 24) | | |
454 | (TCPOLEN_MSS << 16) | | |
455 | opts->mss); | |
456 | } | |
457 | ||
bd0388ae WAS |
458 | if (likely(OPTION_TS & options)) { |
459 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { | |
33ad798c AL |
460 | *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | |
461 | (TCPOLEN_SACK_PERM << 16) | | |
462 | (TCPOPT_TIMESTAMP << 8) | | |
463 | TCPOLEN_TIMESTAMP); | |
bd0388ae | 464 | options &= ~OPTION_SACK_ADVERTISE; |
33ad798c AL |
465 | } else { |
466 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
467 | (TCPOPT_NOP << 16) | | |
468 | (TCPOPT_TIMESTAMP << 8) | | |
469 | TCPOLEN_TIMESTAMP); | |
470 | } | |
471 | *ptr++ = htonl(opts->tsval); | |
472 | *ptr++ = htonl(opts->tsecr); | |
473 | } | |
474 | ||
bd0388ae WAS |
475 | /* Specification requires after timestamp, so do it now. |
476 | * | |
477 | * Consider the pessimal case without authentication. The options | |
478 | * could look like: | |
479 | * MSS(4) + SACK|TS(12) + COOKIE(20) + WSCALE(4) == 40 | |
480 | */ | |
481 | if (unlikely(OPTION_COOKIE_EXTENSION & options)) { | |
482 | __u8 *cookie_copy = opts->hash_location; | |
483 | u8 cookie_size = opts->hash_size; | |
484 | ||
485 | /* 8-bit multiple handled in tcp_cookie_size_check() above, | |
486 | * and elsewhere. | |
487 | */ | |
488 | if (0x2 & cookie_size) { | |
489 | __u8 *p = (__u8 *)ptr; | |
490 | ||
491 | /* 16-bit multiple */ | |
492 | *p++ = TCPOPT_COOKIE; | |
493 | *p++ = TCPOLEN_COOKIE_BASE + cookie_size; | |
494 | *p++ = *cookie_copy++; | |
495 | *p++ = *cookie_copy++; | |
496 | ptr++; | |
497 | cookie_size -= 2; | |
498 | } else { | |
499 | /* 32-bit multiple */ | |
500 | *ptr++ = htonl(((TCPOPT_NOP << 24) | | |
501 | (TCPOPT_NOP << 16) | | |
502 | (TCPOPT_COOKIE << 8) | | |
503 | TCPOLEN_COOKIE_BASE) + | |
504 | cookie_size); | |
505 | } | |
506 | ||
507 | if (cookie_size > 0) { | |
508 | memcpy(ptr, cookie_copy, cookie_size); | |
509 | ptr += (cookie_size / 4); | |
510 | } | |
511 | } | |
512 | ||
513 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { | |
33ad798c AL |
514 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
515 | (TCPOPT_NOP << 16) | | |
516 | (TCPOPT_SACK_PERM << 8) | | |
517 | TCPOLEN_SACK_PERM); | |
518 | } | |
519 | ||
bd0388ae | 520 | if (unlikely(OPTION_WSCALE & options)) { |
33ad798c AL |
521 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
522 | (TCPOPT_WINDOW << 16) | | |
523 | (TCPOLEN_WINDOW << 8) | | |
524 | opts->ws); | |
525 | } | |
526 | ||
527 | if (unlikely(opts->num_sack_blocks)) { | |
528 | struct tcp_sack_block *sp = tp->rx_opt.dsack ? | |
529 | tp->duplicate_sack : tp->selective_acks; | |
40efc6fa SH |
530 | int this_sack; |
531 | ||
532 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
533 | (TCPOPT_NOP << 16) | | |
534 | (TCPOPT_SACK << 8) | | |
33ad798c | 535 | (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * |
40efc6fa | 536 | TCPOLEN_SACK_PERBLOCK))); |
2de979bd | 537 | |
33ad798c AL |
538 | for (this_sack = 0; this_sack < opts->num_sack_blocks; |
539 | ++this_sack) { | |
40efc6fa SH |
540 | *ptr++ = htonl(sp[this_sack].start_seq); |
541 | *ptr++ = htonl(sp[this_sack].end_seq); | |
542 | } | |
2de979bd | 543 | |
5861f8e5 | 544 | tp->rx_opt.dsack = 0; |
40efc6fa | 545 | } |
33ad798c AL |
546 | } |
547 | ||
67edfef7 AK |
548 | /* Compute TCP options for SYN packets. This is not the final |
549 | * network wire format yet. | |
550 | */ | |
33ad798c AL |
551 | static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb, |
552 | struct tcp_out_options *opts, | |
553 | struct tcp_md5sig_key **md5) { | |
554 | struct tcp_sock *tp = tcp_sk(sk); | |
bd0388ae | 555 | struct tcp_cookie_values *cvp = tp->cookie_values; |
1aba721e | 556 | struct dst_entry *dst = __sk_dst_get(sk); |
bd0388ae WAS |
557 | unsigned remaining = MAX_TCP_OPTION_SPACE; |
558 | u8 cookie_size = (!tp->rx_opt.cookie_out_never && cvp != NULL) ? | |
559 | tcp_cookie_size_check(cvp->cookie_desired) : | |
560 | 0; | |
33ad798c | 561 | |
cfb6eeb4 | 562 | #ifdef CONFIG_TCP_MD5SIG |
33ad798c AL |
563 | *md5 = tp->af_specific->md5_lookup(sk, sk); |
564 | if (*md5) { | |
565 | opts->options |= OPTION_MD5; | |
bd0388ae | 566 | remaining -= TCPOLEN_MD5SIG_ALIGNED; |
cfb6eeb4 | 567 | } |
33ad798c AL |
568 | #else |
569 | *md5 = NULL; | |
cfb6eeb4 | 570 | #endif |
33ad798c AL |
571 | |
572 | /* We always get an MSS option. The option bytes which will be seen in | |
573 | * normal data packets should timestamps be used, must be in the MSS | |
574 | * advertised. But we subtract them from tp->mss_cache so that | |
575 | * calculations in tcp_sendmsg are simpler etc. So account for this | |
576 | * fact here if necessary. If we don't do this correctly, as a | |
577 | * receiver we won't recognize data packets as being full sized when we | |
578 | * should, and thus we won't abide by the delayed ACK rules correctly. | |
579 | * SACKs don't matter, we never delay an ACK when we have any of those | |
580 | * going out. */ | |
581 | opts->mss = tcp_advertise_mss(sk); | |
bd0388ae | 582 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c | 583 | |
cda42ebd GBY |
584 | if (likely(sysctl_tcp_timestamps && |
585 | !dst_feature(dst, RTAX_FEATURE_NO_TSTAMP) && | |
586 | *md5 == NULL)) { | |
33ad798c AL |
587 | opts->options |= OPTION_TS; |
588 | opts->tsval = TCP_SKB_CB(skb)->when; | |
589 | opts->tsecr = tp->rx_opt.ts_recent; | |
bd0388ae | 590 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c | 591 | } |
345cda2f GBY |
592 | if (likely(sysctl_tcp_window_scaling && |
593 | !dst_feature(dst, RTAX_FEATURE_NO_WSCALE))) { | |
33ad798c | 594 | opts->ws = tp->rx_opt.rcv_wscale; |
89e95a61 | 595 | opts->options |= OPTION_WSCALE; |
bd0388ae | 596 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 597 | } |
1aba721e GBY |
598 | if (likely(sysctl_tcp_sack && |
599 | !dst_feature(dst, RTAX_FEATURE_NO_SACK))) { | |
33ad798c | 600 | opts->options |= OPTION_SACK_ADVERTISE; |
b32d1310 | 601 | if (unlikely(!(OPTION_TS & opts->options))) |
bd0388ae | 602 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c AL |
603 | } |
604 | ||
bd0388ae WAS |
605 | /* Note that timestamps are required by the specification. |
606 | * | |
607 | * Odd numbers of bytes are prohibited by the specification, ensuring | |
608 | * that the cookie is 16-bit aligned, and the resulting cookie pair is | |
609 | * 32-bit aligned. | |
610 | */ | |
611 | if (*md5 == NULL && | |
612 | (OPTION_TS & opts->options) && | |
613 | cookie_size > 0) { | |
614 | int need = TCPOLEN_COOKIE_BASE + cookie_size; | |
615 | ||
616 | if (0x2 & need) { | |
617 | /* 32-bit multiple */ | |
618 | need += 2; /* NOPs */ | |
619 | ||
620 | if (need > remaining) { | |
621 | /* try shrinking cookie to fit */ | |
622 | cookie_size -= 2; | |
623 | need -= 4; | |
624 | } | |
625 | } | |
626 | while (need > remaining && TCP_COOKIE_MIN <= cookie_size) { | |
627 | cookie_size -= 4; | |
628 | need -= 4; | |
629 | } | |
630 | if (TCP_COOKIE_MIN <= cookie_size) { | |
631 | opts->options |= OPTION_COOKIE_EXTENSION; | |
632 | opts->hash_location = (__u8 *)&cvp->cookie_pair[0]; | |
633 | opts->hash_size = cookie_size; | |
634 | ||
635 | /* Remember for future incarnations. */ | |
636 | cvp->cookie_desired = cookie_size; | |
637 | ||
638 | if (cvp->cookie_desired != cvp->cookie_pair_size) { | |
639 | /* Currently use random bytes as a nonce, | |
640 | * assuming these are completely unpredictable | |
641 | * by hostile users of the same system. | |
642 | */ | |
643 | get_random_bytes(&cvp->cookie_pair[0], | |
644 | cookie_size); | |
645 | cvp->cookie_pair_size = cookie_size; | |
646 | } | |
647 | ||
648 | remaining -= need; | |
649 | } | |
650 | } | |
651 | return MAX_TCP_OPTION_SPACE - remaining; | |
40efc6fa SH |
652 | } |
653 | ||
67edfef7 | 654 | /* Set up TCP options for SYN-ACKs. */ |
33ad798c AL |
655 | static unsigned tcp_synack_options(struct sock *sk, |
656 | struct request_sock *req, | |
657 | unsigned mss, struct sk_buff *skb, | |
658 | struct tcp_out_options *opts, | |
4957faad WAS |
659 | struct tcp_md5sig_key **md5, |
660 | struct tcp_extend_values *xvp) | |
661 | { | |
33ad798c | 662 | struct inet_request_sock *ireq = inet_rsk(req); |
4957faad WAS |
663 | unsigned remaining = MAX_TCP_OPTION_SPACE; |
664 | u8 cookie_plus = (xvp != NULL && !xvp->cookie_out_never) ? | |
665 | xvp->cookie_plus : | |
666 | 0; | |
667 | bool doing_ts = ireq->tstamp_ok; | |
33ad798c | 668 | |
cfb6eeb4 | 669 | #ifdef CONFIG_TCP_MD5SIG |
33ad798c AL |
670 | *md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req); |
671 | if (*md5) { | |
672 | opts->options |= OPTION_MD5; | |
4957faad WAS |
673 | remaining -= TCPOLEN_MD5SIG_ALIGNED; |
674 | ||
675 | /* We can't fit any SACK blocks in a packet with MD5 + TS | |
676 | * options. There was discussion about disabling SACK | |
677 | * rather than TS in order to fit in better with old, | |
678 | * buggy kernels, but that was deemed to be unnecessary. | |
679 | */ | |
680 | doing_ts &= !ireq->sack_ok; | |
cfb6eeb4 | 681 | } |
33ad798c AL |
682 | #else |
683 | *md5 = NULL; | |
cfb6eeb4 | 684 | #endif |
33ad798c | 685 | |
4957faad | 686 | /* We always send an MSS option. */ |
33ad798c | 687 | opts->mss = mss; |
4957faad | 688 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c AL |
689 | |
690 | if (likely(ireq->wscale_ok)) { | |
691 | opts->ws = ireq->rcv_wscale; | |
89e95a61 | 692 | opts->options |= OPTION_WSCALE; |
4957faad | 693 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c AL |
694 | } |
695 | if (likely(doing_ts)) { | |
696 | opts->options |= OPTION_TS; | |
697 | opts->tsval = TCP_SKB_CB(skb)->when; | |
698 | opts->tsecr = req->ts_recent; | |
4957faad | 699 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c AL |
700 | } |
701 | if (likely(ireq->sack_ok)) { | |
702 | opts->options |= OPTION_SACK_ADVERTISE; | |
703 | if (unlikely(!doing_ts)) | |
4957faad | 704 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c AL |
705 | } |
706 | ||
4957faad WAS |
707 | /* Similar rationale to tcp_syn_options() applies here, too. |
708 | * If the <SYN> options fit, the same options should fit now! | |
709 | */ | |
710 | if (*md5 == NULL && | |
711 | doing_ts && | |
712 | cookie_plus > TCPOLEN_COOKIE_BASE) { | |
713 | int need = cookie_plus; /* has TCPOLEN_COOKIE_BASE */ | |
714 | ||
715 | if (0x2 & need) { | |
716 | /* 32-bit multiple */ | |
717 | need += 2; /* NOPs */ | |
718 | } | |
719 | if (need <= remaining) { | |
720 | opts->options |= OPTION_COOKIE_EXTENSION; | |
721 | opts->hash_size = cookie_plus - TCPOLEN_COOKIE_BASE; | |
722 | remaining -= need; | |
723 | } else { | |
724 | /* There's no error return, so flag it. */ | |
725 | xvp->cookie_out_never = 1; /* true */ | |
726 | opts->hash_size = 0; | |
727 | } | |
728 | } | |
729 | return MAX_TCP_OPTION_SPACE - remaining; | |
33ad798c AL |
730 | } |
731 | ||
67edfef7 AK |
732 | /* Compute TCP options for ESTABLISHED sockets. This is not the |
733 | * final wire format yet. | |
734 | */ | |
33ad798c AL |
735 | static unsigned tcp_established_options(struct sock *sk, struct sk_buff *skb, |
736 | struct tcp_out_options *opts, | |
737 | struct tcp_md5sig_key **md5) { | |
738 | struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL; | |
739 | struct tcp_sock *tp = tcp_sk(sk); | |
740 | unsigned size = 0; | |
cabeccbd | 741 | unsigned int eff_sacks; |
33ad798c AL |
742 | |
743 | #ifdef CONFIG_TCP_MD5SIG | |
744 | *md5 = tp->af_specific->md5_lookup(sk, sk); | |
745 | if (unlikely(*md5)) { | |
746 | opts->options |= OPTION_MD5; | |
747 | size += TCPOLEN_MD5SIG_ALIGNED; | |
748 | } | |
749 | #else | |
750 | *md5 = NULL; | |
751 | #endif | |
752 | ||
753 | if (likely(tp->rx_opt.tstamp_ok)) { | |
754 | opts->options |= OPTION_TS; | |
755 | opts->tsval = tcb ? tcb->when : 0; | |
756 | opts->tsecr = tp->rx_opt.ts_recent; | |
757 | size += TCPOLEN_TSTAMP_ALIGNED; | |
758 | } | |
759 | ||
cabeccbd IJ |
760 | eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; |
761 | if (unlikely(eff_sacks)) { | |
33ad798c AL |
762 | const unsigned remaining = MAX_TCP_OPTION_SPACE - size; |
763 | opts->num_sack_blocks = | |
cabeccbd | 764 | min_t(unsigned, eff_sacks, |
33ad798c AL |
765 | (remaining - TCPOLEN_SACK_BASE_ALIGNED) / |
766 | TCPOLEN_SACK_PERBLOCK); | |
767 | size += TCPOLEN_SACK_BASE_ALIGNED + | |
768 | opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; | |
769 | } | |
770 | ||
771 | return size; | |
40efc6fa | 772 | } |
1da177e4 LT |
773 | |
774 | /* This routine actually transmits TCP packets queued in by | |
775 | * tcp_do_sendmsg(). This is used by both the initial | |
776 | * transmission and possible later retransmissions. | |
777 | * All SKB's seen here are completely headerless. It is our | |
778 | * job to build the TCP header, and pass the packet down to | |
779 | * IP so it can do the same plus pass the packet off to the | |
780 | * device. | |
781 | * | |
782 | * We are working here with either a clone of the original | |
783 | * SKB, or a fresh unique copy made by the retransmit engine. | |
784 | */ | |
056834d9 IJ |
785 | static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, |
786 | gfp_t gfp_mask) | |
1da177e4 | 787 | { |
dfb4b9dc DM |
788 | const struct inet_connection_sock *icsk = inet_csk(sk); |
789 | struct inet_sock *inet; | |
790 | struct tcp_sock *tp; | |
791 | struct tcp_skb_cb *tcb; | |
33ad798c AL |
792 | struct tcp_out_options opts; |
793 | unsigned tcp_options_size, tcp_header_size; | |
cfb6eeb4 | 794 | struct tcp_md5sig_key *md5; |
dfb4b9dc | 795 | struct tcphdr *th; |
dfb4b9dc DM |
796 | int err; |
797 | ||
798 | BUG_ON(!skb || !tcp_skb_pcount(skb)); | |
799 | ||
800 | /* If congestion control is doing timestamping, we must | |
801 | * take such a timestamp before we potentially clone/copy. | |
802 | */ | |
164891aa | 803 | if (icsk->icsk_ca_ops->flags & TCP_CONG_RTT_STAMP) |
dfb4b9dc DM |
804 | __net_timestamp(skb); |
805 | ||
806 | if (likely(clone_it)) { | |
807 | if (unlikely(skb_cloned(skb))) | |
808 | skb = pskb_copy(skb, gfp_mask); | |
809 | else | |
810 | skb = skb_clone(skb, gfp_mask); | |
811 | if (unlikely(!skb)) | |
812 | return -ENOBUFS; | |
813 | } | |
1da177e4 | 814 | |
dfb4b9dc DM |
815 | inet = inet_sk(sk); |
816 | tp = tcp_sk(sk); | |
817 | tcb = TCP_SKB_CB(skb); | |
33ad798c | 818 | memset(&opts, 0, sizeof(opts)); |
1da177e4 | 819 | |
33ad798c AL |
820 | if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) |
821 | tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); | |
822 | else | |
823 | tcp_options_size = tcp_established_options(sk, skb, &opts, | |
824 | &md5); | |
825 | tcp_header_size = tcp_options_size + sizeof(struct tcphdr); | |
e905a9ed | 826 | |
dfb4b9dc DM |
827 | if (tcp_packets_in_flight(tp) == 0) |
828 | tcp_ca_event(sk, CA_EVENT_TX_START); | |
829 | ||
aa8223c7 ACM |
830 | skb_push(skb, tcp_header_size); |
831 | skb_reset_transport_header(skb); | |
e89862f4 | 832 | skb_set_owner_w(skb, sk); |
dfb4b9dc DM |
833 | |
834 | /* Build TCP header and checksum it. */ | |
aa8223c7 | 835 | th = tcp_hdr(skb); |
c720c7e8 ED |
836 | th->source = inet->inet_sport; |
837 | th->dest = inet->inet_dport; | |
dfb4b9dc DM |
838 | th->seq = htonl(tcb->seq); |
839 | th->ack_seq = htonl(tp->rcv_nxt); | |
df7a3b07 | 840 | *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | |
dfb4b9dc DM |
841 | tcb->flags); |
842 | ||
843 | if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) { | |
844 | /* RFC1323: The window in SYN & SYN/ACK segments | |
845 | * is never scaled. | |
846 | */ | |
600ff0c2 | 847 | th->window = htons(min(tp->rcv_wnd, 65535U)); |
dfb4b9dc DM |
848 | } else { |
849 | th->window = htons(tcp_select_window(sk)); | |
850 | } | |
851 | th->check = 0; | |
852 | th->urg_ptr = 0; | |
1da177e4 | 853 | |
33f5f57e | 854 | /* The urg_mode check is necessary during a below snd_una win probe */ |
7691367d HX |
855 | if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { |
856 | if (before(tp->snd_up, tcb->seq + 0x10000)) { | |
857 | th->urg_ptr = htons(tp->snd_up - tcb->seq); | |
858 | th->urg = 1; | |
859 | } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { | |
860 | th->urg_ptr = 0xFFFF; | |
861 | th->urg = 1; | |
862 | } | |
dfb4b9dc | 863 | } |
1da177e4 | 864 | |
bd0388ae | 865 | tcp_options_write((__be32 *)(th + 1), tp, &opts); |
33ad798c | 866 | if (likely((tcb->flags & TCPCB_FLAG_SYN) == 0)) |
9e412ba7 | 867 | TCP_ECN_send(sk, skb, tcp_header_size); |
1da177e4 | 868 | |
cfb6eeb4 YH |
869 | #ifdef CONFIG_TCP_MD5SIG |
870 | /* Calculate the MD5 hash, as we have all we need now */ | |
871 | if (md5) { | |
33ad798c | 872 | sk->sk_route_caps &= ~NETIF_F_GSO_MASK; |
bd0388ae | 873 | tp->af_specific->calc_md5_hash(opts.hash_location, |
49a72dfb | 874 | md5, sk, NULL, skb); |
cfb6eeb4 YH |
875 | } |
876 | #endif | |
877 | ||
8292a17a | 878 | icsk->icsk_af_ops->send_check(sk, skb->len, skb); |
1da177e4 | 879 | |
dfb4b9dc DM |
880 | if (likely(tcb->flags & TCPCB_FLAG_ACK)) |
881 | tcp_event_ack_sent(sk, tcp_skb_pcount(skb)); | |
1da177e4 | 882 | |
dfb4b9dc DM |
883 | if (skb->len != tcp_header_size) |
884 | tcp_event_data_sent(tp, skb, sk); | |
1da177e4 | 885 | |
bd37a088 | 886 | if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) |
81cc8a75 | 887 | TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); |
1da177e4 | 888 | |
e89862f4 | 889 | err = icsk->icsk_af_ops->queue_xmit(skb, 0); |
83de47cd | 890 | if (likely(err <= 0)) |
dfb4b9dc DM |
891 | return err; |
892 | ||
3cfe3baa | 893 | tcp_enter_cwr(sk, 1); |
dfb4b9dc | 894 | |
b9df3cb8 | 895 | return net_xmit_eval(err); |
1da177e4 LT |
896 | } |
897 | ||
67edfef7 | 898 | /* This routine just queues the buffer for sending. |
1da177e4 LT |
899 | * |
900 | * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, | |
901 | * otherwise socket can stall. | |
902 | */ | |
903 | static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) | |
904 | { | |
905 | struct tcp_sock *tp = tcp_sk(sk); | |
906 | ||
907 | /* Advance write_seq and place onto the write_queue. */ | |
908 | tp->write_seq = TCP_SKB_CB(skb)->end_seq; | |
909 | skb_header_release(skb); | |
fe067e8a | 910 | tcp_add_write_queue_tail(sk, skb); |
3ab224be HA |
911 | sk->sk_wmem_queued += skb->truesize; |
912 | sk_mem_charge(sk, skb->truesize); | |
1da177e4 LT |
913 | } |
914 | ||
67edfef7 | 915 | /* Initialize TSO segments for a packet. */ |
056834d9 IJ |
916 | static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb, |
917 | unsigned int mss_now) | |
f6302d1d | 918 | { |
8e5b9dda HX |
919 | if (skb->len <= mss_now || !sk_can_gso(sk) || |
920 | skb->ip_summed == CHECKSUM_NONE) { | |
f6302d1d DM |
921 | /* Avoid the costly divide in the normal |
922 | * non-TSO case. | |
923 | */ | |
7967168c HX |
924 | skb_shinfo(skb)->gso_segs = 1; |
925 | skb_shinfo(skb)->gso_size = 0; | |
926 | skb_shinfo(skb)->gso_type = 0; | |
f6302d1d | 927 | } else { |
356f89e1 | 928 | skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss_now); |
7967168c | 929 | skb_shinfo(skb)->gso_size = mss_now; |
bcd76111 | 930 | skb_shinfo(skb)->gso_type = sk->sk_gso_type; |
1da177e4 LT |
931 | } |
932 | } | |
933 | ||
91fed7a1 | 934 | /* When a modification to fackets out becomes necessary, we need to check |
68f8353b | 935 | * skb is counted to fackets_out or not. |
91fed7a1 | 936 | */ |
a47e5a98 | 937 | static void tcp_adjust_fackets_out(struct sock *sk, struct sk_buff *skb, |
91fed7a1 IJ |
938 | int decr) |
939 | { | |
a47e5a98 IJ |
940 | struct tcp_sock *tp = tcp_sk(sk); |
941 | ||
dc86967b | 942 | if (!tp->sacked_out || tcp_is_reno(tp)) |
91fed7a1 IJ |
943 | return; |
944 | ||
6859d494 | 945 | if (after(tcp_highest_sack_seq(tp), TCP_SKB_CB(skb)->seq)) |
91fed7a1 | 946 | tp->fackets_out -= decr; |
91fed7a1 IJ |
947 | } |
948 | ||
797108d1 IJ |
949 | /* Pcount in the middle of the write queue got changed, we need to do various |
950 | * tweaks to fix counters | |
951 | */ | |
952 | static void tcp_adjust_pcount(struct sock *sk, struct sk_buff *skb, int decr) | |
953 | { | |
954 | struct tcp_sock *tp = tcp_sk(sk); | |
955 | ||
956 | tp->packets_out -= decr; | |
957 | ||
958 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
959 | tp->sacked_out -= decr; | |
960 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) | |
961 | tp->retrans_out -= decr; | |
962 | if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) | |
963 | tp->lost_out -= decr; | |
964 | ||
965 | /* Reno case is special. Sigh... */ | |
966 | if (tcp_is_reno(tp) && decr > 0) | |
967 | tp->sacked_out -= min_t(u32, tp->sacked_out, decr); | |
968 | ||
969 | tcp_adjust_fackets_out(sk, skb, decr); | |
970 | ||
971 | if (tp->lost_skb_hint && | |
972 | before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && | |
52cf3cc8 | 973 | (tcp_is_fack(tp) || (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))) |
797108d1 IJ |
974 | tp->lost_cnt_hint -= decr; |
975 | ||
976 | tcp_verify_left_out(tp); | |
977 | } | |
978 | ||
1da177e4 LT |
979 | /* Function to create two new TCP segments. Shrinks the given segment |
980 | * to the specified size and appends a new segment with the rest of the | |
e905a9ed | 981 | * packet to the list. This won't be called frequently, I hope. |
1da177e4 LT |
982 | * Remember, these are still headerless SKBs at this point. |
983 | */ | |
056834d9 IJ |
984 | int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, |
985 | unsigned int mss_now) | |
1da177e4 LT |
986 | { |
987 | struct tcp_sock *tp = tcp_sk(sk); | |
988 | struct sk_buff *buff; | |
6475be16 | 989 | int nsize, old_factor; |
b60b49ea | 990 | int nlen; |
9ce01461 | 991 | u8 flags; |
1da177e4 | 992 | |
b2cc99f0 | 993 | BUG_ON(len > skb->len); |
6a438bbe | 994 | |
1da177e4 LT |
995 | nsize = skb_headlen(skb) - len; |
996 | if (nsize < 0) | |
997 | nsize = 0; | |
998 | ||
999 | if (skb_cloned(skb) && | |
1000 | skb_is_nonlinear(skb) && | |
1001 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) | |
1002 | return -ENOMEM; | |
1003 | ||
1004 | /* Get a new skb... force flag on. */ | |
1005 | buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC); | |
1006 | if (buff == NULL) | |
1007 | return -ENOMEM; /* We'll just try again later. */ | |
ef5cb973 | 1008 | |
3ab224be HA |
1009 | sk->sk_wmem_queued += buff->truesize; |
1010 | sk_mem_charge(sk, buff->truesize); | |
b60b49ea HX |
1011 | nlen = skb->len - len - nsize; |
1012 | buff->truesize += nlen; | |
1013 | skb->truesize -= nlen; | |
1da177e4 LT |
1014 | |
1015 | /* Correct the sequence numbers. */ | |
1016 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1017 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1018 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1019 | ||
1020 | /* PSH and FIN should only be set in the second packet. */ | |
1021 | flags = TCP_SKB_CB(skb)->flags; | |
056834d9 | 1022 | TCP_SKB_CB(skb)->flags = flags & ~(TCPCB_FLAG_FIN | TCPCB_FLAG_PSH); |
1da177e4 | 1023 | TCP_SKB_CB(buff)->flags = flags; |
e14c3caf | 1024 | TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; |
1da177e4 | 1025 | |
84fa7933 | 1026 | if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) { |
1da177e4 | 1027 | /* Copy and checksum data tail into the new buffer. */ |
056834d9 IJ |
1028 | buff->csum = csum_partial_copy_nocheck(skb->data + len, |
1029 | skb_put(buff, nsize), | |
1da177e4 LT |
1030 | nsize, 0); |
1031 | ||
1032 | skb_trim(skb, len); | |
1033 | ||
1034 | skb->csum = csum_block_sub(skb->csum, buff->csum, len); | |
1035 | } else { | |
84fa7933 | 1036 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 LT |
1037 | skb_split(skb, buff, len); |
1038 | } | |
1039 | ||
1040 | buff->ip_summed = skb->ip_summed; | |
1041 | ||
1042 | /* Looks stupid, but our code really uses when of | |
1043 | * skbs, which it never sent before. --ANK | |
1044 | */ | |
1045 | TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when; | |
a61bbcf2 | 1046 | buff->tstamp = skb->tstamp; |
1da177e4 | 1047 | |
6475be16 DM |
1048 | old_factor = tcp_skb_pcount(skb); |
1049 | ||
1da177e4 | 1050 | /* Fix up tso_factor for both original and new SKB. */ |
846998ae DM |
1051 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
1052 | tcp_set_skb_tso_segs(sk, buff, mss_now); | |
1da177e4 | 1053 | |
6475be16 DM |
1054 | /* If this packet has been sent out already, we must |
1055 | * adjust the various packet counters. | |
1056 | */ | |
cf0b450c | 1057 | if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { |
6475be16 DM |
1058 | int diff = old_factor - tcp_skb_pcount(skb) - |
1059 | tcp_skb_pcount(buff); | |
1da177e4 | 1060 | |
797108d1 IJ |
1061 | if (diff) |
1062 | tcp_adjust_pcount(sk, skb, diff); | |
1da177e4 LT |
1063 | } |
1064 | ||
1065 | /* Link BUFF into the send queue. */ | |
f44b5271 | 1066 | skb_header_release(buff); |
fe067e8a | 1067 | tcp_insert_write_queue_after(skb, buff, sk); |
1da177e4 LT |
1068 | |
1069 | return 0; | |
1070 | } | |
1071 | ||
1072 | /* This is similar to __pskb_pull_head() (it will go to core/skbuff.c | |
1073 | * eventually). The difference is that pulled data not copied, but | |
1074 | * immediately discarded. | |
1075 | */ | |
f2911969 | 1076 | static void __pskb_trim_head(struct sk_buff *skb, int len) |
1da177e4 LT |
1077 | { |
1078 | int i, k, eat; | |
1079 | ||
1080 | eat = len; | |
1081 | k = 0; | |
056834d9 | 1082 | for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { |
1da177e4 LT |
1083 | if (skb_shinfo(skb)->frags[i].size <= eat) { |
1084 | put_page(skb_shinfo(skb)->frags[i].page); | |
1085 | eat -= skb_shinfo(skb)->frags[i].size; | |
1086 | } else { | |
1087 | skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i]; | |
1088 | if (eat) { | |
1089 | skb_shinfo(skb)->frags[k].page_offset += eat; | |
1090 | skb_shinfo(skb)->frags[k].size -= eat; | |
1091 | eat = 0; | |
1092 | } | |
1093 | k++; | |
1094 | } | |
1095 | } | |
1096 | skb_shinfo(skb)->nr_frags = k; | |
1097 | ||
27a884dc | 1098 | skb_reset_tail_pointer(skb); |
1da177e4 LT |
1099 | skb->data_len -= len; |
1100 | skb->len = skb->data_len; | |
1da177e4 LT |
1101 | } |
1102 | ||
67edfef7 | 1103 | /* Remove acked data from a packet in the transmit queue. */ |
1da177e4 LT |
1104 | int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) |
1105 | { | |
056834d9 | 1106 | if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) |
1da177e4 LT |
1107 | return -ENOMEM; |
1108 | ||
f2911969 HXP |
1109 | /* If len == headlen, we avoid __skb_pull to preserve alignment. */ |
1110 | if (unlikely(len < skb_headlen(skb))) | |
1da177e4 | 1111 | __skb_pull(skb, len); |
f2911969 HXP |
1112 | else |
1113 | __pskb_trim_head(skb, len - skb_headlen(skb)); | |
1da177e4 LT |
1114 | |
1115 | TCP_SKB_CB(skb)->seq += len; | |
84fa7933 | 1116 | skb->ip_summed = CHECKSUM_PARTIAL; |
1da177e4 LT |
1117 | |
1118 | skb->truesize -= len; | |
1119 | sk->sk_wmem_queued -= len; | |
3ab224be | 1120 | sk_mem_uncharge(sk, len); |
1da177e4 LT |
1121 | sock_set_flag(sk, SOCK_QUEUE_SHRUNK); |
1122 | ||
1123 | /* Any change of skb->len requires recalculation of tso | |
1124 | * factor and mss. | |
1125 | */ | |
1126 | if (tcp_skb_pcount(skb) > 1) | |
0c54b85f | 1127 | tcp_set_skb_tso_segs(sk, skb, tcp_current_mss(sk)); |
1da177e4 LT |
1128 | |
1129 | return 0; | |
1130 | } | |
1131 | ||
67edfef7 | 1132 | /* Calculate MSS. Not accounting for SACKs here. */ |
5d424d5a JH |
1133 | int tcp_mtu_to_mss(struct sock *sk, int pmtu) |
1134 | { | |
1135 | struct tcp_sock *tp = tcp_sk(sk); | |
1136 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1137 | int mss_now; | |
1138 | ||
1139 | /* Calculate base mss without TCP options: | |
1140 | It is MMS_S - sizeof(tcphdr) of rfc1122 | |
1141 | */ | |
1142 | mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); | |
1143 | ||
1144 | /* Clamp it (mss_clamp does not include tcp options) */ | |
1145 | if (mss_now > tp->rx_opt.mss_clamp) | |
1146 | mss_now = tp->rx_opt.mss_clamp; | |
1147 | ||
1148 | /* Now subtract optional transport overhead */ | |
1149 | mss_now -= icsk->icsk_ext_hdr_len; | |
1150 | ||
1151 | /* Then reserve room for full set of TCP options and 8 bytes of data */ | |
1152 | if (mss_now < 48) | |
1153 | mss_now = 48; | |
1154 | ||
1155 | /* Now subtract TCP options size, not including SACKs */ | |
1156 | mss_now -= tp->tcp_header_len - sizeof(struct tcphdr); | |
1157 | ||
1158 | return mss_now; | |
1159 | } | |
1160 | ||
1161 | /* Inverse of above */ | |
1162 | int tcp_mss_to_mtu(struct sock *sk, int mss) | |
1163 | { | |
1164 | struct tcp_sock *tp = tcp_sk(sk); | |
1165 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1166 | int mtu; | |
1167 | ||
1168 | mtu = mss + | |
1169 | tp->tcp_header_len + | |
1170 | icsk->icsk_ext_hdr_len + | |
1171 | icsk->icsk_af_ops->net_header_len; | |
1172 | ||
1173 | return mtu; | |
1174 | } | |
1175 | ||
67edfef7 | 1176 | /* MTU probing init per socket */ |
5d424d5a JH |
1177 | void tcp_mtup_init(struct sock *sk) |
1178 | { | |
1179 | struct tcp_sock *tp = tcp_sk(sk); | |
1180 | struct inet_connection_sock *icsk = inet_csk(sk); | |
1181 | ||
1182 | icsk->icsk_mtup.enabled = sysctl_tcp_mtu_probing > 1; | |
1183 | icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + | |
e905a9ed | 1184 | icsk->icsk_af_ops->net_header_len; |
5d424d5a JH |
1185 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, sysctl_tcp_base_mss); |
1186 | icsk->icsk_mtup.probe_size = 0; | |
1187 | } | |
1188 | ||
1da177e4 LT |
1189 | /* This function synchronize snd mss to current pmtu/exthdr set. |
1190 | ||
1191 | tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts | |
1192 | for TCP options, but includes only bare TCP header. | |
1193 | ||
1194 | tp->rx_opt.mss_clamp is mss negotiated at connection setup. | |
caa20d9a | 1195 | It is minimum of user_mss and mss received with SYN. |
1da177e4 LT |
1196 | It also does not include TCP options. |
1197 | ||
d83d8461 | 1198 | inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. |
1da177e4 LT |
1199 | |
1200 | tp->mss_cache is current effective sending mss, including | |
1201 | all tcp options except for SACKs. It is evaluated, | |
1202 | taking into account current pmtu, but never exceeds | |
1203 | tp->rx_opt.mss_clamp. | |
1204 | ||
1205 | NOTE1. rfc1122 clearly states that advertised MSS | |
1206 | DOES NOT include either tcp or ip options. | |
1207 | ||
d83d8461 ACM |
1208 | NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache |
1209 | are READ ONLY outside this function. --ANK (980731) | |
1da177e4 | 1210 | */ |
1da177e4 LT |
1211 | unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) |
1212 | { | |
1213 | struct tcp_sock *tp = tcp_sk(sk); | |
d83d8461 | 1214 | struct inet_connection_sock *icsk = inet_csk(sk); |
5d424d5a | 1215 | int mss_now; |
1da177e4 | 1216 | |
5d424d5a JH |
1217 | if (icsk->icsk_mtup.search_high > pmtu) |
1218 | icsk->icsk_mtup.search_high = pmtu; | |
1da177e4 | 1219 | |
5d424d5a | 1220 | mss_now = tcp_mtu_to_mss(sk, pmtu); |
409d22b4 | 1221 | mss_now = tcp_bound_to_half_wnd(tp, mss_now); |
1da177e4 LT |
1222 | |
1223 | /* And store cached results */ | |
d83d8461 | 1224 | icsk->icsk_pmtu_cookie = pmtu; |
5d424d5a JH |
1225 | if (icsk->icsk_mtup.enabled) |
1226 | mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); | |
c1b4a7e6 | 1227 | tp->mss_cache = mss_now; |
1da177e4 LT |
1228 | |
1229 | return mss_now; | |
1230 | } | |
1231 | ||
1232 | /* Compute the current effective MSS, taking SACKs and IP options, | |
1233 | * and even PMTU discovery events into account. | |
1da177e4 | 1234 | */ |
0c54b85f | 1235 | unsigned int tcp_current_mss(struct sock *sk) |
1da177e4 LT |
1236 | { |
1237 | struct tcp_sock *tp = tcp_sk(sk); | |
1238 | struct dst_entry *dst = __sk_dst_get(sk); | |
c1b4a7e6 | 1239 | u32 mss_now; |
33ad798c AL |
1240 | unsigned header_len; |
1241 | struct tcp_out_options opts; | |
1242 | struct tcp_md5sig_key *md5; | |
c1b4a7e6 DM |
1243 | |
1244 | mss_now = tp->mss_cache; | |
1245 | ||
1da177e4 LT |
1246 | if (dst) { |
1247 | u32 mtu = dst_mtu(dst); | |
d83d8461 | 1248 | if (mtu != inet_csk(sk)->icsk_pmtu_cookie) |
1da177e4 LT |
1249 | mss_now = tcp_sync_mss(sk, mtu); |
1250 | } | |
1251 | ||
33ad798c AL |
1252 | header_len = tcp_established_options(sk, NULL, &opts, &md5) + |
1253 | sizeof(struct tcphdr); | |
1254 | /* The mss_cache is sized based on tp->tcp_header_len, which assumes | |
1255 | * some common options. If this is an odd packet (because we have SACK | |
1256 | * blocks etc) then our calculated header_len will be different, and | |
1257 | * we have to adjust mss_now correspondingly */ | |
1258 | if (header_len != tp->tcp_header_len) { | |
1259 | int delta = (int) header_len - tp->tcp_header_len; | |
1260 | mss_now -= delta; | |
1261 | } | |
cfb6eeb4 | 1262 | |
1da177e4 LT |
1263 | return mss_now; |
1264 | } | |
1265 | ||
a762a980 | 1266 | /* Congestion window validation. (RFC2861) */ |
9e412ba7 | 1267 | static void tcp_cwnd_validate(struct sock *sk) |
a762a980 | 1268 | { |
9e412ba7 | 1269 | struct tcp_sock *tp = tcp_sk(sk); |
a762a980 | 1270 | |
d436d686 | 1271 | if (tp->packets_out >= tp->snd_cwnd) { |
a762a980 DM |
1272 | /* Network is feed fully. */ |
1273 | tp->snd_cwnd_used = 0; | |
1274 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
1275 | } else { | |
1276 | /* Network starves. */ | |
1277 | if (tp->packets_out > tp->snd_cwnd_used) | |
1278 | tp->snd_cwnd_used = tp->packets_out; | |
1279 | ||
15d33c07 DM |
1280 | if (sysctl_tcp_slow_start_after_idle && |
1281 | (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) | |
a762a980 DM |
1282 | tcp_cwnd_application_limited(sk); |
1283 | } | |
1284 | } | |
1285 | ||
0e3a4803 IJ |
1286 | /* Returns the portion of skb which can be sent right away without |
1287 | * introducing MSS oddities to segment boundaries. In rare cases where | |
1288 | * mss_now != mss_cache, we will request caller to create a small skb | |
1289 | * per input skb which could be mostly avoided here (if desired). | |
5ea3a748 IJ |
1290 | * |
1291 | * We explicitly want to create a request for splitting write queue tail | |
1292 | * to a small skb for Nagle purposes while avoiding unnecessary modulos, | |
1293 | * thus all the complexity (cwnd_len is always MSS multiple which we | |
1294 | * return whenever allowed by the other factors). Basically we need the | |
1295 | * modulo only when the receiver window alone is the limiting factor or | |
1296 | * when we would be allowed to send the split-due-to-Nagle skb fully. | |
0e3a4803 IJ |
1297 | */ |
1298 | static unsigned int tcp_mss_split_point(struct sock *sk, struct sk_buff *skb, | |
056834d9 | 1299 | unsigned int mss_now, unsigned int cwnd) |
c1b4a7e6 | 1300 | { |
0e3a4803 IJ |
1301 | struct tcp_sock *tp = tcp_sk(sk); |
1302 | u32 needed, window, cwnd_len; | |
c1b4a7e6 | 1303 | |
90840def | 1304 | window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
c1b4a7e6 | 1305 | cwnd_len = mss_now * cwnd; |
0e3a4803 IJ |
1306 | |
1307 | if (likely(cwnd_len <= window && skb != tcp_write_queue_tail(sk))) | |
1308 | return cwnd_len; | |
1309 | ||
5ea3a748 IJ |
1310 | needed = min(skb->len, window); |
1311 | ||
17515408 | 1312 | if (cwnd_len <= needed) |
0e3a4803 IJ |
1313 | return cwnd_len; |
1314 | ||
0e3a4803 | 1315 | return needed - needed % mss_now; |
c1b4a7e6 DM |
1316 | } |
1317 | ||
1318 | /* Can at least one segment of SKB be sent right now, according to the | |
1319 | * congestion window rules? If so, return how many segments are allowed. | |
1320 | */ | |
056834d9 IJ |
1321 | static inline unsigned int tcp_cwnd_test(struct tcp_sock *tp, |
1322 | struct sk_buff *skb) | |
c1b4a7e6 DM |
1323 | { |
1324 | u32 in_flight, cwnd; | |
1325 | ||
1326 | /* Don't be strict about the congestion window for the final FIN. */ | |
104439a8 JH |
1327 | if ((TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) && |
1328 | tcp_skb_pcount(skb) == 1) | |
c1b4a7e6 DM |
1329 | return 1; |
1330 | ||
1331 | in_flight = tcp_packets_in_flight(tp); | |
1332 | cwnd = tp->snd_cwnd; | |
1333 | if (in_flight < cwnd) | |
1334 | return (cwnd - in_flight); | |
1335 | ||
1336 | return 0; | |
1337 | } | |
1338 | ||
67edfef7 AK |
1339 | /* Intialize TSO state of a skb. |
1340 | * This must be invoked the first time we consider transmitting | |
c1b4a7e6 DM |
1341 | * SKB onto the wire. |
1342 | */ | |
056834d9 IJ |
1343 | static int tcp_init_tso_segs(struct sock *sk, struct sk_buff *skb, |
1344 | unsigned int mss_now) | |
c1b4a7e6 DM |
1345 | { |
1346 | int tso_segs = tcp_skb_pcount(skb); | |
1347 | ||
f8269a49 | 1348 | if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { |
846998ae | 1349 | tcp_set_skb_tso_segs(sk, skb, mss_now); |
c1b4a7e6 DM |
1350 | tso_segs = tcp_skb_pcount(skb); |
1351 | } | |
1352 | return tso_segs; | |
1353 | } | |
1354 | ||
67edfef7 | 1355 | /* Minshall's variant of the Nagle send check. */ |
c1b4a7e6 DM |
1356 | static inline int tcp_minshall_check(const struct tcp_sock *tp) |
1357 | { | |
09cb105e | 1358 | return after(tp->snd_sml, tp->snd_una) && |
c1b4a7e6 DM |
1359 | !after(tp->snd_sml, tp->snd_nxt); |
1360 | } | |
1361 | ||
1362 | /* Return 0, if packet can be sent now without violation Nagle's rules: | |
1363 | * 1. It is full sized. | |
1364 | * 2. Or it contains FIN. (already checked by caller) | |
1365 | * 3. Or TCP_NODELAY was set. | |
1366 | * 4. Or TCP_CORK is not set, and all sent packets are ACKed. | |
1367 | * With Minshall's modification: all sent small packets are ACKed. | |
1368 | */ | |
c1b4a7e6 | 1369 | static inline int tcp_nagle_check(const struct tcp_sock *tp, |
e905a9ed | 1370 | const struct sk_buff *skb, |
c1b4a7e6 DM |
1371 | unsigned mss_now, int nonagle) |
1372 | { | |
1373 | return (skb->len < mss_now && | |
056834d9 IJ |
1374 | ((nonagle & TCP_NAGLE_CORK) || |
1375 | (!nonagle && tp->packets_out && tcp_minshall_check(tp)))); | |
c1b4a7e6 DM |
1376 | } |
1377 | ||
1378 | /* Return non-zero if the Nagle test allows this packet to be | |
1379 | * sent now. | |
1380 | */ | |
1381 | static inline int tcp_nagle_test(struct tcp_sock *tp, struct sk_buff *skb, | |
1382 | unsigned int cur_mss, int nonagle) | |
1383 | { | |
1384 | /* Nagle rule does not apply to frames, which sit in the middle of the | |
1385 | * write_queue (they have no chances to get new data). | |
1386 | * | |
1387 | * This is implemented in the callers, where they modify the 'nonagle' | |
1388 | * argument based upon the location of SKB in the send queue. | |
1389 | */ | |
1390 | if (nonagle & TCP_NAGLE_PUSH) | |
1391 | return 1; | |
1392 | ||
d551e454 IJ |
1393 | /* Don't use the nagle rule for urgent data (or for the final FIN). |
1394 | * Nagle can be ignored during F-RTO too (see RFC4138). | |
1395 | */ | |
33f5f57e | 1396 | if (tcp_urg_mode(tp) || (tp->frto_counter == 2) || |
c1b4a7e6 DM |
1397 | (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)) |
1398 | return 1; | |
1399 | ||
1400 | if (!tcp_nagle_check(tp, skb, cur_mss, nonagle)) | |
1401 | return 1; | |
1402 | ||
1403 | return 0; | |
1404 | } | |
1405 | ||
1406 | /* Does at least the first segment of SKB fit into the send window? */ | |
056834d9 IJ |
1407 | static inline int tcp_snd_wnd_test(struct tcp_sock *tp, struct sk_buff *skb, |
1408 | unsigned int cur_mss) | |
c1b4a7e6 DM |
1409 | { |
1410 | u32 end_seq = TCP_SKB_CB(skb)->end_seq; | |
1411 | ||
1412 | if (skb->len > cur_mss) | |
1413 | end_seq = TCP_SKB_CB(skb)->seq + cur_mss; | |
1414 | ||
90840def | 1415 | return !after(end_seq, tcp_wnd_end(tp)); |
c1b4a7e6 DM |
1416 | } |
1417 | ||
fe067e8a | 1418 | /* This checks if the data bearing packet SKB (usually tcp_send_head(sk)) |
c1b4a7e6 DM |
1419 | * should be put on the wire right now. If so, it returns the number of |
1420 | * packets allowed by the congestion window. | |
1421 | */ | |
1422 | static unsigned int tcp_snd_test(struct sock *sk, struct sk_buff *skb, | |
1423 | unsigned int cur_mss, int nonagle) | |
1424 | { | |
1425 | struct tcp_sock *tp = tcp_sk(sk); | |
1426 | unsigned int cwnd_quota; | |
1427 | ||
846998ae | 1428 | tcp_init_tso_segs(sk, skb, cur_mss); |
c1b4a7e6 DM |
1429 | |
1430 | if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) | |
1431 | return 0; | |
1432 | ||
1433 | cwnd_quota = tcp_cwnd_test(tp, skb); | |
056834d9 | 1434 | if (cwnd_quota && !tcp_snd_wnd_test(tp, skb, cur_mss)) |
c1b4a7e6 DM |
1435 | cwnd_quota = 0; |
1436 | ||
1437 | return cwnd_quota; | |
1438 | } | |
1439 | ||
67edfef7 | 1440 | /* Test if sending is allowed right now. */ |
9e412ba7 | 1441 | int tcp_may_send_now(struct sock *sk) |
c1b4a7e6 | 1442 | { |
9e412ba7 | 1443 | struct tcp_sock *tp = tcp_sk(sk); |
fe067e8a | 1444 | struct sk_buff *skb = tcp_send_head(sk); |
c1b4a7e6 DM |
1445 | |
1446 | return (skb && | |
0c54b85f | 1447 | tcp_snd_test(sk, skb, tcp_current_mss(sk), |
c1b4a7e6 | 1448 | (tcp_skb_is_last(sk, skb) ? |