Commit | Line | Data |
---|---|---|
8ae0e4b4 | 1 | /* |
8a36cf82 | 2 | * Copyright (c) 1982, 1986, 1988 Regents of the University of California. |
2b6b6284 | 3 | * All rights reserved. |
8ae0e4b4 | 4 | * |
2b6b6284 KB |
5 | * Redistribution and use in source and binary forms are permitted |
6 | * provided that this notice is preserved and that due credit is given | |
7 | * to the University of California at Berkeley. The name of the University | |
8 | * may not be used to endorse or promote products derived from this | |
9 | * software without specific prior written permission. This software | |
10 | * is provided ``as is'' without express or implied warranty. | |
11 | * | |
9e4788e4 | 12 | * @(#)tcp_input.c 7.18 (Berkeley) %G% |
8ae0e4b4 | 13 | */ |
87e78f19 | 14 | |
20666ad3 JB |
15 | #include "param.h" |
16 | #include "systm.h" | |
17 | #include "mbuf.h" | |
18 | #include "protosw.h" | |
19 | #include "socket.h" | |
20 | #include "socketvar.h" | |
21 | #include "errno.h" | |
f4d55810 SL |
22 | |
23 | #include "../net/if.h" | |
c124e997 | 24 | #include "../net/route.h" |
f4d55810 | 25 | |
20666ad3 JB |
26 | #include "in.h" |
27 | #include "in_pcb.h" | |
28 | #include "in_systm.h" | |
29 | #include "ip.h" | |
30 | #include "ip_var.h" | |
31 | #include "tcp.h" | |
32 | #include "tcp_fsm.h" | |
33 | #include "tcp_seq.h" | |
34 | #include "tcp_timer.h" | |
35 | #include "tcp_var.h" | |
36 | #include "tcpip.h" | |
37 | #include "tcp_debug.h" | |
87e78f19 | 38 | |
22856bb8 | 39 | int tcpprintfs = 0; |
60b16fa9 | 40 | int tcpcksum = 1; |
386369f5 | 41 | int tcprexmtthresh = 3; |
4b935108 | 42 | struct tcpiphdr tcp_saveti; |
87e78f19 | 43 | |
4b935108 | 44 | struct tcpcb *tcp_newtcpcb(); |
a17510f3 MK |
45 | |
46 | /* | |
47 | * Insert segment ti into reassembly queue of tcp with | |
48 | * control block tp. Return TH_FIN if reassembly now includes | |
49 | * a segment with FIN. The macro form does the common case inline | |
50 | * (segment is the next to be received on an established connection, | |
51 | * and the queue is empty), avoiding linkage into and removal | |
52 | * from the queue and repetition of various conversions. | |
9e4788e4 MK |
53 | * Set DELACK for segments received in order, but ack immediately |
54 | * when segments are out of order (so fast retransmit can work). | |
a17510f3 MK |
55 | */ |
56 | #define TCP_REASS(tp, ti, m, so, flags) { \ | |
57 | if ((ti)->ti_seq == (tp)->rcv_nxt && \ | |
58 | (tp)->seg_next == (struct tcpiphdr *)(tp) && \ | |
59 | (tp)->t_state == TCPS_ESTABLISHED) { \ | |
9e4788e4 | 60 | tp->t_flags |= TF_DELACK; \ |
a17510f3 MK |
61 | (tp)->rcv_nxt += (ti)->ti_len; \ |
62 | flags = (ti)->ti_flags & TH_FIN; \ | |
96c50630 MK |
63 | tcpstat.tcps_rcvpack++;\ |
64 | tcpstat.tcps_rcvbyte += (ti)->ti_len;\ | |
a17510f3 MK |
65 | sbappend(&(so)->so_rcv, (m)); \ |
66 | sorwakeup(so); \ | |
9e4788e4 | 67 | } else { \ |
a17510f3 | 68 | (flags) = tcp_reass((tp), (ti)); \ |
9e4788e4 MK |
69 | tp->t_flags |= TF_ACKNOW; \ |
70 | } \ | |
a17510f3 MK |
71 | } |
72 | ||
73 | tcp_reass(tp, ti) | |
74 | register struct tcpcb *tp; | |
75 | register struct tcpiphdr *ti; | |
76 | { | |
77 | register struct tcpiphdr *q; | |
78 | struct socket *so = tp->t_inpcb->inp_socket; | |
79 | struct mbuf *m; | |
80 | int flags; | |
81 | ||
82 | /* | |
83 | * Call with ti==0 after become established to | |
84 | * force pre-ESTABLISHED data up to user socket. | |
85 | */ | |
86 | if (ti == 0) | |
87 | goto present; | |
88 | ||
89 | /* | |
90 | * Find a segment which begins after this one does. | |
91 | */ | |
92 | for (q = tp->seg_next; q != (struct tcpiphdr *)tp; | |
93 | q = (struct tcpiphdr *)q->ti_next) | |
94 | if (SEQ_GT(q->ti_seq, ti->ti_seq)) | |
95 | break; | |
96 | ||
97 | /* | |
98 | * If there is a preceding segment, it may provide some of | |
99 | * our data already. If so, drop the data from the incoming | |
100 | * segment. If it provides all of our data, drop us. | |
101 | */ | |
102 | if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { | |
103 | register int i; | |
104 | q = (struct tcpiphdr *)q->ti_prev; | |
105 | /* conversion to int (in i) handles seq wraparound */ | |
106 | i = q->ti_seq + q->ti_len - ti->ti_seq; | |
107 | if (i > 0) { | |
96c50630 MK |
108 | if (i >= ti->ti_len) { |
109 | tcpstat.tcps_rcvduppack++; | |
110 | tcpstat.tcps_rcvdupbyte += ti->ti_len; | |
a17510f3 | 111 | goto drop; |
96c50630 | 112 | } |
a17510f3 MK |
113 | m_adj(dtom(ti), i); |
114 | ti->ti_len -= i; | |
115 | ti->ti_seq += i; | |
116 | } | |
117 | q = (struct tcpiphdr *)(q->ti_next); | |
118 | } | |
96c50630 MK |
119 | tcpstat.tcps_rcvoopack++; |
120 | tcpstat.tcps_rcvoobyte += ti->ti_len; | |
a17510f3 MK |
121 | |
122 | /* | |
123 | * While we overlap succeeding segments trim them or, | |
124 | * if they are completely covered, dequeue them. | |
125 | */ | |
126 | while (q != (struct tcpiphdr *)tp) { | |
127 | register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; | |
128 | if (i <= 0) | |
129 | break; | |
130 | if (i < q->ti_len) { | |
131 | q->ti_seq += i; | |
132 | q->ti_len -= i; | |
133 | m_adj(dtom(q), i); | |
134 | break; | |
135 | } | |
136 | q = (struct tcpiphdr *)q->ti_next; | |
137 | m = dtom(q->ti_prev); | |
138 | remque(q->ti_prev); | |
139 | m_freem(m); | |
140 | } | |
141 | ||
142 | /* | |
143 | * Stick new segment in its place. | |
144 | */ | |
145 | insque(ti, q->ti_prev); | |
146 | ||
147 | present: | |
148 | /* | |
149 | * Present data to user, advancing rcv_nxt through | |
150 | * completed sequence space. | |
151 | */ | |
152 | if (TCPS_HAVERCVDSYN(tp->t_state) == 0) | |
153 | return (0); | |
154 | ti = tp->seg_next; | |
155 | if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) | |
156 | return (0); | |
157 | if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) | |
158 | return (0); | |
159 | do { | |
160 | tp->rcv_nxt += ti->ti_len; | |
161 | flags = ti->ti_flags & TH_FIN; | |
162 | remque(ti); | |
163 | m = dtom(ti); | |
164 | ti = (struct tcpiphdr *)ti->ti_next; | |
165 | if (so->so_state & SS_CANTRCVMORE) | |
166 | m_freem(m); | |
167 | else | |
168 | sbappend(&so->so_rcv, m); | |
169 | } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); | |
170 | sorwakeup(so); | |
171 | return (flags); | |
172 | drop: | |
173 | m_freem(dtom(ti)); | |
174 | return (0); | |
175 | } | |
176 | ||
2ff61f9d BJ |
177 | /* |
178 | * TCP input routine, follows pages 65-76 of the | |
179 | * protocol specification dated September, 1981 very closely. | |
180 | */ | |
2b4b57cd BJ |
181 | tcp_input(m0) |
182 | struct mbuf *m0; | |
87e78f19 | 183 | { |
2b4b57cd | 184 | register struct tcpiphdr *ti; |
53a5409e | 185 | struct inpcb *inp; |
2b4b57cd | 186 | register struct mbuf *m; |
8b5a83bb | 187 | struct mbuf *om = 0; |
2b4b57cd | 188 | int len, tlen, off; |
8e65fd66 | 189 | register struct tcpcb *tp = 0; |
2b4b57cd | 190 | register int tiflags; |
d52566dd | 191 | struct socket *so; |
4859921b | 192 | int todrop, acked, ourfinisacked, needoutput = 0; |
4b935108 | 193 | short ostate; |
ebcadd38 | 194 | struct in_addr laddr; |
7aa16f99 | 195 | int dropsocket = 0; |
96c50630 | 196 | int iss = 0; |
87e78f19 | 197 | |
96c50630 | 198 | tcpstat.tcps_rcvtotal++; |
87e78f19 | 199 | /* |
4aed14e3 BJ |
200 | * Get IP and TCP header together in first mbuf. |
201 | * Note: IP leaves IP header in first mbuf. | |
87e78f19 | 202 | */ |
2b4b57cd | 203 | m = m0; |
20790db4 | 204 | ti = mtod(m, struct tcpiphdr *); |
4aed14e3 | 205 | if (((struct ip *)ti)->ip_hl > (sizeof (struct ip) >> 2)) |
d63599ac | 206 | ip_stripoptions((struct ip *)ti, (struct mbuf *)0); |
6703c41f BJ |
207 | if (m->m_off > MMAXOFF || m->m_len < sizeof (struct tcpiphdr)) { |
208 | if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) { | |
96c50630 | 209 | tcpstat.tcps_rcvshort++; |
6703c41f | 210 | return; |
8a13b737 BJ |
211 | } |
212 | ti = mtod(m, struct tcpiphdr *); | |
213 | } | |
87e78f19 | 214 | |
2b4b57cd | 215 | /* |
4aed14e3 | 216 | * Checksum extended TCP header and data. |
2b4b57cd BJ |
217 | */ |
218 | tlen = ((struct ip *)ti)->ip_len; | |
219 | len = sizeof (struct ip) + tlen; | |
60b16fa9 | 220 | if (tcpcksum) { |
2b4b57cd BJ |
221 | ti->ti_next = ti->ti_prev = 0; |
222 | ti->ti_x1 = 0; | |
ac83b17a | 223 | ti->ti_len = (u_short)tlen; |
668cc26d | 224 | ti->ti_len = htons((u_short)ti->ti_len); |
4b6b94ca | 225 | if (ti->ti_sum = in_cksum(m, len)) { |
ee954ff1 SL |
226 | if (tcpprintfs) |
227 | printf("tcp sum: src %x\n", ti->ti_src); | |
96c50630 | 228 | tcpstat.tcps_rcvbadsum++; |
8a13b737 | 229 | goto drop; |
87e78f19 BJ |
230 | } |
231 | } | |
232 | ||
233 | /* | |
4aed14e3 | 234 | * Check that TCP offset makes sense, |
8b5a83bb | 235 | * pull out TCP options and adjust length. |
87e78f19 | 236 | */ |
2b4b57cd | 237 | off = ti->ti_off << 2; |
4b6b94ca | 238 | if (off < sizeof (struct tcphdr) || off > tlen) { |
ee954ff1 SL |
239 | if (tcpprintfs) |
240 | printf("tcp off: src %x off %d\n", ti->ti_src, off); | |
96c50630 | 241 | tcpstat.tcps_rcvbadoff++; |
8a13b737 | 242 | goto drop; |
2b4b57cd | 243 | } |
1e977657 BJ |
244 | tlen -= off; |
245 | ti->ti_len = tlen; | |
8b5a83bb | 246 | if (off > sizeof (struct tcphdr)) { |
a17510f3 MK |
247 | if (m->m_len < sizeof(struct ip) + off) { |
248 | if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) { | |
96c50630 | 249 | tcpstat.tcps_rcvshort++; |
a17510f3 MK |
250 | return; |
251 | } | |
252 | ti = mtod(m, struct tcpiphdr *); | |
8b5a83bb | 253 | } |
cce93e4b | 254 | om = m_get(M_DONTWAIT, MT_DATA); |
8b5a83bb BJ |
255 | if (om == 0) |
256 | goto drop; | |
8b5a83bb BJ |
257 | om->m_len = off - sizeof (struct tcphdr); |
258 | { caddr_t op = mtod(m, caddr_t) + sizeof (struct tcpiphdr); | |
668cc26d | 259 | bcopy(op, mtod(om, caddr_t), (unsigned)om->m_len); |
8b5a83bb | 260 | m->m_len -= om->m_len; |
668cc26d SL |
261 | bcopy(op+om->m_len, op, |
262 | (unsigned)(m->m_len-sizeof (struct tcpiphdr))); | |
8b5a83bb BJ |
263 | } |
264 | } | |
2ff61f9d | 265 | tiflags = ti->ti_flags; |
2b4b57cd | 266 | |
795e0416 | 267 | /* |
669abecf | 268 | * Drop TCP and IP headers; TCP options were dropped above. |
795e0416 | 269 | */ |
669abecf KM |
270 | m->m_off += sizeof(struct tcpiphdr); |
271 | m->m_len -= sizeof(struct tcpiphdr); | |
795e0416 | 272 | |
8a13b737 | 273 | /* |
4aed14e3 | 274 | * Convert TCP protocol specific fields to host format. |
8a13b737 BJ |
275 | */ |
276 | ti->ti_seq = ntohl(ti->ti_seq); | |
277 | ti->ti_ack = ntohl(ti->ti_ack); | |
278 | ti->ti_win = ntohs(ti->ti_win); | |
279 | ti->ti_urp = ntohs(ti->ti_urp); | |
280 | ||
2b4b57cd | 281 | /* |
8075bb0e | 282 | * Locate pcb for segment. |
2b4b57cd | 283 | */ |
96c50630 | 284 | findpcb: |
2ff61f9d | 285 | inp = in_pcblookup |
ebcadd38 BJ |
286 | (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport, |
287 | INPLOOKUP_WILDCARD); | |
2ff61f9d BJ |
288 | |
289 | /* | |
290 | * If the state is CLOSED (i.e., TCB does not exist) then | |
4aed14e3 | 291 | * all data in the incoming segment is discarded. |
386369f5 MK |
292 | * If the TCB exists but is in CLOSED state, it is embryonic, |
293 | * but should either do a listen or a connect soon. | |
2ff61f9d | 294 | */ |
22856bb8 | 295 | if (inp == 0) |
8a13b737 | 296 | goto dropwithreset; |
2ff61f9d | 297 | tp = intotcpcb(inp); |
22856bb8 | 298 | if (tp == 0) |
8a13b737 | 299 | goto dropwithreset; |
386369f5 MK |
300 | if (tp->t_state == TCPS_CLOSED) |
301 | goto drop; | |
f1b2fa5b | 302 | so = inp->inp_socket; |
4b935108 BJ |
303 | if (so->so_options & SO_DEBUG) { |
304 | ostate = tp->t_state; | |
305 | tcp_saveti = *ti; | |
306 | } | |
ebf42a75 BJ |
307 | if (so->so_options & SO_ACCEPTCONN) { |
308 | so = sonewconn(so); | |
309 | if (so == 0) | |
310 | goto drop; | |
7aa16f99 SL |
311 | /* |
312 | * This is ugly, but .... | |
313 | * | |
314 | * Mark socket as temporary until we're | |
315 | * committed to keeping it. The code at | |
316 | * ``drop'' and ``dropwithreset'' check the | |
317 | * flag dropsocket to see if the temporary | |
318 | * socket created here should be discarded. | |
319 | * We mark the socket as discardable until | |
320 | * we're committed to it below in TCPS_LISTEN. | |
321 | */ | |
322 | dropsocket++; | |
ebf42a75 BJ |
323 | inp = (struct inpcb *)so->so_pcb; |
324 | inp->inp_laddr = ti->ti_dst; | |
325 | inp->inp_lport = ti->ti_dport; | |
9d866d2f | 326 | #if BSD>=43 |
a17510f3 | 327 | inp->inp_options = ip_srcroute(); |
9d866d2f | 328 | #endif |
ebf42a75 BJ |
329 | tp = intotcpcb(inp); |
330 | tp->t_state = TCPS_LISTEN; | |
331 | } | |
87e78f19 | 332 | |
405c9168 BJ |
333 | /* |
334 | * Segment received on connection. | |
335 | * Reset idle time and keep-alive timer. | |
336 | */ | |
337 | tp->t_idle = 0; | |
8a36cf82 | 338 | tp->t_timer[TCPT_KEEP] = tcp_keepidle; |
405c9168 | 339 | |
8b5a83bb | 340 | /* |
99578149 MK |
341 | * Process options if not in LISTEN state, |
342 | * else do it below (after getting remote address). | |
8b5a83bb | 343 | */ |
99578149 MK |
344 | if (om && tp->t_state != TCPS_LISTEN) { |
345 | tcp_dooptions(tp, om, ti); | |
8b5a83bb BJ |
346 | om = 0; |
347 | } | |
348 | ||
87e78f19 | 349 | /* |
8a13b737 BJ |
350 | * Calculate amount of space in receive window, |
351 | * and then do TCP input processing. | |
a17510f3 MK |
352 | * Receive window is amount of space in rcv queue, |
353 | * but not less than advertised window. | |
87e78f19 | 354 | */ |
bbaaf0fd MK |
355 | { int win; |
356 | ||
357 | win = sbspace(&so->so_rcv); | |
358 | if (win < 0) | |
359 | win = 0; | |
360 | tp->rcv_wnd = MAX(win, (int)(tp->rcv_adv - tp->rcv_nxt)); | |
361 | } | |
2ff61f9d | 362 | |
87e78f19 BJ |
363 | switch (tp->t_state) { |
364 | ||
2ff61f9d BJ |
365 | /* |
366 | * If the state is LISTEN then ignore segment if it contains an RST. | |
367 | * If the segment contains an ACK then it is bad and send a RST. | |
368 | * If it does not contain a SYN then it is not interesting; drop it. | |
224f3a72 | 369 | * Don't bother responding if the destination was a broadcast. |
8a13b737 | 370 | * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial |
2ff61f9d | 371 | * tp->iss, and send a segment: |
8a13b737 | 372 | * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> |
2ff61f9d BJ |
373 | * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. |
374 | * Fill in remote peer address fields if not previously specified. | |
375 | * Enter SYN_RECEIVED state, and process any other fields of this | |
4aed14e3 | 376 | * segment in this state. |
2ff61f9d | 377 | */ |
8075bb0e | 378 | case TCPS_LISTEN: { |
789d2a39 | 379 | struct mbuf *am; |
8075bb0e BJ |
380 | register struct sockaddr_in *sin; |
381 | ||
2ff61f9d BJ |
382 | if (tiflags & TH_RST) |
383 | goto drop; | |
22856bb8 | 384 | if (tiflags & TH_ACK) |
8a13b737 | 385 | goto dropwithreset; |
22856bb8 | 386 | if ((tiflags & TH_SYN) == 0) |
2ff61f9d | 387 | goto drop; |
224f3a72 MK |
388 | if (in_broadcast(ti->ti_dst)) |
389 | goto drop; | |
789d2a39 SL |
390 | am = m_get(M_DONTWAIT, MT_SONAME); |
391 | if (am == NULL) | |
392 | goto drop; | |
393 | am->m_len = sizeof (struct sockaddr_in); | |
a8d3bf7f | 394 | sin = mtod(am, struct sockaddr_in *); |
8075bb0e BJ |
395 | sin->sin_family = AF_INET; |
396 | sin->sin_addr = ti->ti_src; | |
397 | sin->sin_port = ti->ti_sport; | |
ebcadd38 | 398 | laddr = inp->inp_laddr; |
789d2a39 | 399 | if (inp->inp_laddr.s_addr == INADDR_ANY) |
ebcadd38 | 400 | inp->inp_laddr = ti->ti_dst; |
a8d3bf7f | 401 | if (in_pcbconnect(inp, am)) { |
ebcadd38 | 402 | inp->inp_laddr = laddr; |
5a1f132a | 403 | (void) m_free(am); |
4aed14e3 | 404 | goto drop; |
ebcadd38 | 405 | } |
5a1f132a | 406 | (void) m_free(am); |
4aed14e3 BJ |
407 | tp->t_template = tcp_template(tp); |
408 | if (tp->t_template == 0) { | |
8011f5df | 409 | tp = tcp_drop(tp, ENOBUFS); |
a4f7ea71 | 410 | dropsocket = 0; /* socket is already gone */ |
4aed14e3 BJ |
411 | goto drop; |
412 | } | |
99578149 MK |
413 | if (om) { |
414 | tcp_dooptions(tp, om, ti); | |
415 | om = 0; | |
416 | } | |
96c50630 MK |
417 | if (iss) |
418 | tp->iss = iss; | |
419 | else | |
420 | tp->iss = tcp_iss; | |
421 | tcp_iss += TCP_ISSINCR/2; | |
2ff61f9d | 422 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
423 | tcp_sendseqinit(tp); |
424 | tcp_rcvseqinit(tp); | |
bbaaf0fd | 425 | tp->t_flags |= TF_ACKNOW; |
2ff61f9d | 426 | tp->t_state = TCPS_SYN_RECEIVED; |
8a36cf82 | 427 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT; |
7aa16f99 | 428 | dropsocket = 0; /* committed to socket */ |
96c50630 | 429 | tcpstat.tcps_accepts++; |
8a13b737 | 430 | goto trimthenstep6; |
8075bb0e | 431 | } |
87e78f19 | 432 | |
2ff61f9d BJ |
433 | /* |
434 | * If the state is SYN_SENT: | |
435 | * if seg contains an ACK, but not for our SYN, drop the input. | |
436 | * if seg contains a RST, then drop the connection. | |
437 | * if seg does not contain SYN, then drop it. | |
438 | * Otherwise this is an acceptable SYN segment | |
439 | * initialize tp->rcv_nxt and tp->irs | |
440 | * if seg contains ack then advance tp->snd_una | |
441 | * if SYN has been acked change to ESTABLISHED else SYN_RCVD state | |
442 | * arrange for segment to be acked (eventually) | |
443 | * continue processing rest of data/controls, beginning with URG | |
444 | */ | |
445 | case TCPS_SYN_SENT: | |
446 | if ((tiflags & TH_ACK) && | |
a17510f3 | 447 | (SEQ_LEQ(ti->ti_ack, tp->iss) || |
4b6b94ca | 448 | SEQ_GT(ti->ti_ack, tp->snd_max))) |
8a13b737 | 449 | goto dropwithreset; |
2ff61f9d | 450 | if (tiflags & TH_RST) { |
0e3936fa SL |
451 | if (tiflags & TH_ACK) |
452 | tp = tcp_drop(tp, ECONNREFUSED); | |
2ff61f9d | 453 | goto drop; |
87e78f19 | 454 | } |
2ff61f9d BJ |
455 | if ((tiflags & TH_SYN) == 0) |
456 | goto drop; | |
b57e9490 MK |
457 | if (tiflags & TH_ACK) { |
458 | tp->snd_una = ti->ti_ack; | |
459 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) | |
460 | tp->snd_nxt = tp->snd_una; | |
461 | } | |
4aed14e3 | 462 | tp->t_timer[TCPT_REXMT] = 0; |
2ff61f9d | 463 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
464 | tcp_rcvseqinit(tp); |
465 | tp->t_flags |= TF_ACKNOW; | |
b57e9490 | 466 | if (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) { |
96c50630 | 467 | tcpstat.tcps_connects++; |
4aed14e3 | 468 | soisconnected(so); |
2ff61f9d | 469 | tp->t_state = TCPS_ESTABLISHED; |
99578149 | 470 | tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp)); |
405c9168 | 471 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
386369f5 MK |
472 | /* |
473 | * if we didn't have to retransmit the SYN, | |
474 | * use its rtt as our initial srtt & rtt var. | |
475 | */ | |
476 | if (tp->t_rtt) { | |
477 | tp->t_srtt = tp->t_rtt << 3; | |
478 | tp->t_rttvar = tp->t_rtt << 1; | |
479 | TCPT_RANGESET(tp->t_rxtcur, | |
480 | ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, | |
481 | TCPTV_MIN, TCPTV_REXMTMAX); | |
482 | tp->t_rtt = 0; | |
483 | } | |
405c9168 | 484 | } else |
8a13b737 | 485 | tp->t_state = TCPS_SYN_RECEIVED; |
8a13b737 BJ |
486 | |
487 | trimthenstep6: | |
488 | /* | |
4b6b94ca | 489 | * Advance ti->ti_seq to correspond to first data byte. |
8a13b737 BJ |
490 | * If data, trim to stay within window, |
491 | * dropping FIN if necessary. | |
492 | */ | |
4b6b94ca | 493 | ti->ti_seq++; |
8a13b737 BJ |
494 | if (ti->ti_len > tp->rcv_wnd) { |
495 | todrop = ti->ti_len - tp->rcv_wnd; | |
9d866d2f | 496 | #if BSD>=43 |
8a13b737 | 497 | m_adj(m, -todrop); |
9d866d2f MK |
498 | #else |
499 | /* XXX work around 4.2 m_adj bug */ | |
500 | if (m->m_len) { | |
501 | m_adj(m, -todrop); | |
502 | } else { | |
503 | /* skip tcp/ip header in first mbuf */ | |
504 | m_adj(m->m_next, -todrop); | |
505 | } | |
506 | #endif | |
8a13b737 | 507 | ti->ti_len = tp->rcv_wnd; |
bbaaf0fd | 508 | tiflags &= ~TH_FIN; |
96c50630 MK |
509 | tcpstat.tcps_rcvpackafterwin++; |
510 | tcpstat.tcps_rcvbyteafterwin += todrop; | |
87e78f19 | 511 | } |
e832edbc | 512 | tp->snd_wl1 = ti->ti_seq - 1; |
bbaaf0fd | 513 | tp->rcv_up = ti->ti_seq; |
8a13b737 | 514 | goto step6; |
2ff61f9d | 515 | } |
87e78f19 | 516 | |
2ff61f9d BJ |
517 | /* |
518 | * States other than LISTEN or SYN_SENT. | |
519 | * First check that at least some bytes of segment are within | |
96c50630 MK |
520 | * receive window. If segment begins before rcv_nxt, |
521 | * drop leading data (and SYN); if nothing left, just ack. | |
2ff61f9d | 522 | */ |
96c50630 MK |
523 | todrop = tp->rcv_nxt - ti->ti_seq; |
524 | if (todrop > 0) { | |
525 | if (tiflags & TH_SYN) { | |
526 | tiflags &= ~TH_SYN; | |
527 | ti->ti_seq++; | |
528 | if (ti->ti_urp > 1) | |
529 | ti->ti_urp--; | |
530 | else | |
531 | tiflags &= ~TH_URG; | |
532 | todrop--; | |
533 | } | |
534 | if (todrop > ti->ti_len || | |
535 | todrop == ti->ti_len && (tiflags&TH_FIN) == 0) { | |
8a36cf82 MK |
536 | tcpstat.tcps_rcvduppack++; |
537 | tcpstat.tcps_rcvdupbyte += ti->ti_len; | |
39b02f3c | 538 | /* |
8a36cf82 MK |
539 | * If segment is just one to the left of the window, |
540 | * check two special cases: | |
541 | * 1. Don't toss RST in response to 4.2-style keepalive. | |
542 | * 2. If the only thing to drop is a FIN, we can drop | |
543 | * it, but check the ACK or we will get into FIN | |
544 | * wars if our FINs crossed (both CLOSING). | |
545 | * In either case, send ACK to resynchronize, | |
546 | * but keep on processing for RST or ACK. | |
39b02f3c | 547 | */ |
8a36cf82 MK |
548 | if ((tiflags & TH_FIN && todrop == ti->ti_len + 1) |
549 | #ifdef TCP_COMPAT_42 | |
550 | || (tiflags & TH_RST && ti->ti_seq == tp->rcv_nxt - 1) | |
39b02f3c | 551 | #endif |
8a36cf82 MK |
552 | ) { |
553 | todrop = ti->ti_len; | |
554 | tiflags &= ~TH_FIN; | |
555 | tp->t_flags |= TF_ACKNOW; | |
556 | } else | |
557 | goto dropafterack; | |
a6bbda13 MK |
558 | } else { |
559 | tcpstat.tcps_rcvpartduppack++; | |
560 | tcpstat.tcps_rcvpartdupbyte += todrop; | |
96c50630 | 561 | } |
96c50630 MK |
562 | m_adj(m, todrop); |
563 | ti->ti_seq += todrop; | |
564 | ti->ti_len -= todrop; | |
565 | if (ti->ti_urp > todrop) | |
566 | ti->ti_urp -= todrop; | |
567 | else { | |
568 | tiflags &= ~TH_URG; | |
569 | ti->ti_urp = 0; | |
570 | } | |
571 | } | |
572 | ||
b819e9ea | 573 | /* |
8a36cf82 | 574 | * If new data are received on a connection after the |
b819e9ea MK |
575 | * user processes are gone, then RST the other end. |
576 | */ | |
577 | if ((so->so_state & SS_NOFDREF) && | |
578 | tp->t_state > TCPS_CLOSE_WAIT && ti->ti_len) { | |
579 | tp = tcp_close(tp); | |
580 | tcpstat.tcps_rcvafterclose++; | |
581 | goto dropwithreset; | |
582 | } | |
583 | ||
4f182c3f MK |
584 | /* |
585 | * If segment ends after window, drop trailing data | |
586 | * (and PUSH and FIN); if nothing left, just ACK. | |
587 | */ | |
588 | todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); | |
589 | if (todrop > 0) { | |
590 | tcpstat.tcps_rcvpackafterwin++; | |
591 | if (todrop >= ti->ti_len) { | |
96c50630 | 592 | tcpstat.tcps_rcvbyteafterwin += ti->ti_len; |
4f182c3f MK |
593 | /* |
594 | * If a new connection request is received | |
595 | * while in TIME_WAIT, drop the old connection | |
596 | * and start over if the sequence numbers | |
597 | * are above the previous ones. | |
598 | */ | |
599 | if (tiflags & TH_SYN && | |
600 | tp->t_state == TCPS_TIME_WAIT && | |
601 | SEQ_GT(ti->ti_seq, tp->rcv_nxt)) { | |
602 | iss = tp->rcv_nxt + TCP_ISSINCR; | |
603 | (void) tcp_close(tp); | |
604 | goto findpcb; | |
96c50630 | 605 | } |
4f182c3f MK |
606 | /* |
607 | * If window is closed can only take segments at | |
608 | * window edge, and have to drop data and PUSH from | |
609 | * incoming segments. Continue processing, but | |
610 | * remember to ack. Otherwise, drop segment | |
611 | * and ack. | |
612 | */ | |
613 | if (tp->rcv_wnd == 0 && ti->ti_seq == tp->rcv_nxt) { | |
614 | tp->t_flags |= TF_ACKNOW; | |
615 | tcpstat.tcps_rcvwinprobe++; | |
616 | } else | |
2ff61f9d | 617 | goto dropafterack; |
4f182c3f | 618 | } else |
96c50630 | 619 | tcpstat.tcps_rcvbyteafterwin += todrop; |
9d866d2f | 620 | #if BSD>=43 |
4f182c3f | 621 | m_adj(m, -todrop); |
9d866d2f MK |
622 | #else |
623 | /* XXX work around m_adj bug */ | |
624 | if (m->m_len) { | |
625 | m_adj(m, -todrop); | |
626 | } else { | |
627 | /* skip tcp/ip header in first mbuf */ | |
628 | m_adj(m->m_next, -todrop); | |
629 | } | |
630 | #endif | |
4f182c3f MK |
631 | ti->ti_len -= todrop; |
632 | tiflags &= ~(TH_PUSH|TH_FIN); | |
87e78f19 | 633 | } |
87e78f19 | 634 | |
87e78f19 | 635 | /* |
2ff61f9d BJ |
636 | * If the RST bit is set examine the state: |
637 | * SYN_RECEIVED STATE: | |
638 | * If passive open, return to LISTEN state. | |
639 | * If active open, inform user that connection was refused. | |
640 | * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: | |
641 | * Inform user that connection was reset, and close tcb. | |
642 | * CLOSING, LAST_ACK, TIME_WAIT STATES | |
643 | * Close the tcb. | |
87e78f19 | 644 | */ |
2ff61f9d | 645 | if (tiflags&TH_RST) switch (tp->t_state) { |
4b935108 | 646 | |
2ff61f9d | 647 | case TCPS_SYN_RECEIVED: |
8a36cf82 MK |
648 | so->so_error = ECONNREFUSED; |
649 | goto close; | |
2ff61f9d BJ |
650 | |
651 | case TCPS_ESTABLISHED: | |
652 | case TCPS_FIN_WAIT_1: | |
653 | case TCPS_FIN_WAIT_2: | |
654 | case TCPS_CLOSE_WAIT: | |
8a36cf82 MK |
655 | so->so_error = ECONNRESET; |
656 | close: | |
657 | tp->t_state = TCPS_CLOSED; | |
658 | tcpstat.tcps_drops++; | |
659 | tp = tcp_close(tp); | |
2ff61f9d BJ |
660 | goto drop; |
661 | ||
662 | case TCPS_CLOSING: | |
663 | case TCPS_LAST_ACK: | |
664 | case TCPS_TIME_WAIT: | |
0e3936fa | 665 | tp = tcp_close(tp); |
2ff61f9d | 666 | goto drop; |
87e78f19 | 667 | } |
87e78f19 BJ |
668 | |
669 | /* | |
2ff61f9d BJ |
670 | * If a SYN is in the window, then this is an |
671 | * error and we send an RST and drop the connection. | |
672 | */ | |
673 | if (tiflags & TH_SYN) { | |
0e3936fa | 674 | tp = tcp_drop(tp, ECONNRESET); |
8a13b737 | 675 | goto dropwithreset; |
2ff61f9d BJ |
676 | } |
677 | ||
678 | /* | |
679 | * If the ACK bit is off we drop the segment and return. | |
680 | */ | |
8a13b737 | 681 | if ((tiflags & TH_ACK) == 0) |
2ff61f9d BJ |
682 | goto drop; |
683 | ||
684 | /* | |
685 | * Ack processing. | |
87e78f19 | 686 | */ |
87e78f19 BJ |
687 | switch (tp->t_state) { |
688 | ||
2ff61f9d BJ |
689 | /* |
690 | * In SYN_RECEIVED state if the ack ACKs our SYN then enter | |
4859921b | 691 | * ESTABLISHED state and continue processing, otherwise |
2ff61f9d BJ |
692 | * send an RST. |
693 | */ | |
694 | case TCPS_SYN_RECEIVED: | |
8a13b737 | 695 | if (SEQ_GT(tp->snd_una, ti->ti_ack) || |
4b6b94ca | 696 | SEQ_GT(ti->ti_ack, tp->snd_max)) |
8a13b737 | 697 | goto dropwithreset; |
96c50630 | 698 | tcpstat.tcps_connects++; |
8a13b737 BJ |
699 | soisconnected(so); |
700 | tp->t_state = TCPS_ESTABLISHED; | |
99578149 | 701 | tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp)); |
405c9168 | 702 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
4aed14e3 | 703 | tp->snd_wl1 = ti->ti_seq - 1; |
8a13b737 | 704 | /* fall into ... */ |
87e78f19 | 705 | |
2ff61f9d BJ |
706 | /* |
707 | * In ESTABLISHED state: drop duplicate ACKs; ACK out of range | |
708 | * ACKs. If the ack is in the range | |
4b6b94ca | 709 | * tp->snd_una < ti->ti_ack <= tp->snd_max |
2ff61f9d BJ |
710 | * then advance tp->snd_una to ti->ti_ack and drop |
711 | * data from the retransmission queue. If this ACK reflects | |
712 | * more up to date window information we update our window information. | |
713 | */ | |
714 | case TCPS_ESTABLISHED: | |
715 | case TCPS_FIN_WAIT_1: | |
716 | case TCPS_FIN_WAIT_2: | |
717 | case TCPS_CLOSE_WAIT: | |
718 | case TCPS_CLOSING: | |
4aed14e3 BJ |
719 | case TCPS_LAST_ACK: |
720 | case TCPS_TIME_WAIT: | |
8a13b737 | 721 | |
96c50630 | 722 | if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) { |
386369f5 | 723 | if (ti->ti_len == 0 && ti->ti_win == tp->snd_wnd) { |
96c50630 | 724 | tcpstat.tcps_rcvdupack++; |
386369f5 MK |
725 | /* |
726 | * If we have outstanding data (not a | |
727 | * window probe), this is a completely | |
728 | * duplicate ack (ie, window info didn't | |
729 | * change), the ack is the biggest we've | |
730 | * seen and we've seen exactly our rexmt | |
731 | * threshhold of them, assume a packet | |
732 | * has been dropped and retransmit it. | |
733 | * Kludge snd_nxt & the congestion | |
734 | * window so we send only this one | |
3c317835 MK |
735 | * packet. If this packet fills the |
736 | * only hole in the receiver's seq. | |
737 | * space, the next real ack will fully | |
738 | * open our window. This means we | |
739 | * have to do the usual slow-start to | |
740 | * not overwhelm an intermediate gateway | |
741 | * with a burst of packets. Leave | |
742 | * here with the congestion window set | |
743 | * to allow 2 packets on the next real | |
744 | * ack and the exp-to-linear thresh | |
745 | * set for half the current window | |
746 | * size (since we know we're losing at | |
747 | * the current window size). | |
386369f5 MK |
748 | */ |
749 | if (tp->t_timer[TCPT_REXMT] == 0 || | |
750 | ti->ti_ack != tp->snd_una) | |
751 | tp->t_dupacks = 0; | |
752 | else if (++tp->t_dupacks == tcprexmtthresh) { | |
753 | tcp_seq onxt = tp->snd_nxt; | |
3c317835 MK |
754 | u_int win = |
755 | MIN(tp->snd_wnd, tp->snd_cwnd) / 2 / | |
756 | tp->t_maxseg; | |
757 | ||
758 | if (win < 2) | |
759 | win = 2; | |
760 | tp->snd_ssthresh = win * tp->t_maxseg; | |
386369f5 MK |
761 | |
762 | tp->t_timer[TCPT_REXMT] = 0; | |
763 | tp->t_rtt = 0; | |
764 | tp->snd_nxt = ti->ti_ack; | |
765 | tp->snd_cwnd = tp->t_maxseg; | |
766 | (void) tcp_output(tp); | |
767 | ||
386369f5 MK |
768 | if (SEQ_GT(onxt, tp->snd_nxt)) |
769 | tp->snd_nxt = onxt; | |
770 | goto drop; | |
771 | } | |
772 | } else | |
773 | tp->t_dupacks = 0; | |
2ff61f9d | 774 | break; |
96c50630 | 775 | } |
386369f5 | 776 | tp->t_dupacks = 0; |
96c50630 MK |
777 | if (SEQ_GT(ti->ti_ack, tp->snd_max)) { |
778 | tcpstat.tcps_rcvacktoomuch++; | |
2ff61f9d | 779 | goto dropafterack; |
96c50630 | 780 | } |
8a13b737 | 781 | acked = ti->ti_ack - tp->snd_una; |
96c50630 MK |
782 | tcpstat.tcps_rcvackpack++; |
783 | tcpstat.tcps_rcvackbyte += acked; | |
dd020fc8 BJ |
784 | |
785 | /* | |
786 | * If transmit timer is running and timed sequence | |
787 | * number was acked, update smoothed round trip time. | |
a6bbda13 MK |
788 | * Since we now have an rtt measurement, cancel the |
789 | * timer backoff (cf., Phil Karn's retransmit alg.). | |
790 | * Recompute the initial retransmit timer. | |
dd020fc8 BJ |
791 | */ |
792 | if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { | |
96c50630 | 793 | tcpstat.tcps_rttupdated++; |
7cc62c26 MK |
794 | if (tp->t_srtt != 0) { |
795 | register short delta; | |
796 | ||
797 | /* | |
798 | * srtt is stored as fixed point with 3 bits | |
799 | * after the binary point (i.e., scaled by 8). | |
800 | * The following magic is equivalent | |
801 | * to the smoothing algorithm in rfc793 | |
802 | * with an alpha of .875 | |
803 | * (srtt = rtt/8 + srtt*7/8 in fixed point). | |
386369f5 | 804 | * Adjust t_rtt to origin 0. |
7cc62c26 | 805 | */ |
8a36cf82 | 806 | delta = tp->t_rtt - 1 - (tp->t_srtt >> 3); |
7cc62c26 MK |
807 | if ((tp->t_srtt += delta) <= 0) |
808 | tp->t_srtt = 1; | |
809 | /* | |
a6bbda13 MK |
810 | * We accumulate a smoothed rtt variance |
811 | * (actually, a smoothed mean difference), | |
7cc62c26 MK |
812 | * then set the retransmit timer to smoothed |
813 | * rtt + 2 times the smoothed variance. | |
386369f5 | 814 | * rttvar is stored as fixed point |
7cc62c26 MK |
815 | * with 2 bits after the binary point |
816 | * (scaled by 4). The following is equivalent | |
817 | * to rfc793 smoothing with an alpha of .75 | |
818 | * (rttvar = rttvar*3/4 + |delta| / 4). | |
819 | * This replaces rfc793's wired-in beta. | |
820 | */ | |
821 | if (delta < 0) | |
822 | delta = -delta; | |
823 | delta -= (tp->t_rttvar >> 2); | |
824 | if ((tp->t_rttvar += delta) <= 0) | |
825 | tp->t_rttvar = 1; | |
826 | } else { | |
827 | /* | |
828 | * No rtt measurement yet - use the | |
829 | * unsmoothed rtt. Set the variance | |
830 | * to half the rtt (so our first | |
831 | * retransmit happens at 2*rtt) | |
832 | */ | |
833 | tp->t_srtt = tp->t_rtt << 3; | |
834 | tp->t_rttvar = tp->t_rtt << 1; | |
835 | } | |
dd020fc8 | 836 | tp->t_rtt = 0; |
a6bbda13 MK |
837 | tp->t_rxtshift = 0; |
838 | TCPT_RANGESET(tp->t_rxtcur, | |
839 | ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, | |
840 | TCPTV_MIN, TCPTV_REXMTMAX); | |
dd020fc8 BJ |
841 | } |
842 | ||
91039e49 MK |
843 | /* |
844 | * If all outstanding data is acked, stop retransmit | |
845 | * timer and remember to restart (more output or persist). | |
846 | * If there is more data to be acked, restart retransmit | |
a6bbda13 | 847 | * timer, using current (possibly backed-off) value. |
91039e49 MK |
848 | */ |
849 | if (ti->ti_ack == tp->snd_max) { | |
4aed14e3 | 850 | tp->t_timer[TCPT_REXMT] = 0; |
91039e49 | 851 | needoutput = 1; |
a6bbda13 MK |
852 | } else if (tp->t_timer[TCPT_PERSIST] == 0) |
853 | tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; | |
1e9621b8 | 854 | /* |
386369f5 MK |
855 | * When new data is acked, open the congestion window. |
856 | * If the window gives us less than ssthresh packets | |
857 | * in flight, open exponentially (maxseg per packet). | |
858 | * Otherwise open linearly (maxseg per window, | |
859 | * or maxseg^2 / cwnd per packet). | |
1e9621b8 | 860 | */ |
386369f5 MK |
861 | { |
862 | u_int incr = tp->t_maxseg; | |
863 | ||
864 | if (tp->snd_cwnd > tp->snd_ssthresh) | |
865 | incr = MAX(incr * incr / tp->snd_cwnd, 1); | |
866 | ||
5d1f4090 | 867 | tp->snd_cwnd = MIN(tp->snd_cwnd + incr, IP_MAXPACKET); /* XXX */ |
386369f5 | 868 | } |
6703c41f | 869 | if (acked > so->so_snd.sb_cc) { |
6703c41f | 870 | tp->snd_wnd -= so->so_snd.sb_cc; |
8011f5df | 871 | sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); |
4859921b | 872 | ourfinisacked = 1; |
6703c41f | 873 | } else { |
668cc26d | 874 | sbdrop(&so->so_snd, acked); |
6703c41f | 875 | tp->snd_wnd -= acked; |
4859921b | 876 | ourfinisacked = 0; |
6703c41f | 877 | } |
5744ed2b | 878 | if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel) |
22856bb8 | 879 | sowwakeup(so); |
4b6b94ca | 880 | tp->snd_una = ti->ti_ack; |
b8977237 BJ |
881 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
882 | tp->snd_nxt = tp->snd_una; | |
405c9168 | 883 | |
87e78f19 BJ |
884 | switch (tp->t_state) { |
885 | ||
2ff61f9d BJ |
886 | /* |
887 | * In FIN_WAIT_1 STATE in addition to the processing | |
888 | * for the ESTABLISHED state if our FIN is now acknowledged | |
8a13b737 | 889 | * then enter FIN_WAIT_2. |
2ff61f9d BJ |
890 | */ |
891 | case TCPS_FIN_WAIT_1: | |
fdae4427 BJ |
892 | if (ourfinisacked) { |
893 | /* | |
894 | * If we can't receive any more | |
895 | * data, then closing user can proceed. | |
a17510f3 MK |
896 | * Starting the timer is contrary to the |
897 | * specification, but if we don't get a FIN | |
898 | * we'll hang forever. | |
fdae4427 | 899 | */ |
a17510f3 | 900 | if (so->so_state & SS_CANTRCVMORE) { |
fdae4427 | 901 | soisdisconnected(so); |
8a36cf82 | 902 | tp->t_timer[TCPT_2MSL] = tcp_maxidle; |
a17510f3 | 903 | } |
8a13b737 | 904 | tp->t_state = TCPS_FIN_WAIT_2; |
fdae4427 | 905 | } |
87e78f19 BJ |
906 | break; |
907 | ||
2ff61f9d BJ |
908 | /* |
909 | * In CLOSING STATE in addition to the processing for | |
910 | * the ESTABLISHED state if the ACK acknowledges our FIN | |
911 | * then enter the TIME-WAIT state, otherwise ignore | |
912 | * the segment. | |
913 | */ | |
914 | case TCPS_CLOSING: | |
4aed14e3 | 915 | if (ourfinisacked) { |
2ff61f9d | 916 | tp->t_state = TCPS_TIME_WAIT; |
4aed14e3 BJ |
917 | tcp_canceltimers(tp); |
918 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; | |
919 | soisdisconnected(so); | |
920 | } | |
921 | break; | |
87e78f19 | 922 | |
2ff61f9d | 923 | /* |
e20bac9c MK |
924 | * In LAST_ACK, we may still be waiting for data to drain |
925 | * and/or to be acked, as well as for the ack of our FIN. | |
926 | * If our FIN is now acknowledged, delete the TCB, | |
927 | * enter the closed state and return. | |
2ff61f9d BJ |
928 | */ |
929 | case TCPS_LAST_ACK: | |
e20bac9c | 930 | if (ourfinisacked) { |
0e3936fa | 931 | tp = tcp_close(tp); |
e20bac9c MK |
932 | goto drop; |
933 | } | |
934 | break; | |
87e78f19 | 935 | |
2ff61f9d BJ |
936 | /* |
937 | * In TIME_WAIT state the only thing that should arrive | |
938 | * is a retransmission of the remote FIN. Acknowledge | |
939 | * it and restart the finack timer. | |
940 | */ | |
941 | case TCPS_TIME_WAIT: | |
405c9168 | 942 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 943 | goto dropafterack; |
87e78f19 | 944 | } |
8a13b737 | 945 | } |
87e78f19 | 946 | |
2ff61f9d | 947 | step6: |
4aed14e3 BJ |
948 | /* |
949 | * Update window information. | |
bbaaf0fd | 950 | * Don't look at window if no ACK: TAC's send garbage on first SYN. |
4aed14e3 | 951 | */ |
bbaaf0fd MK |
952 | if ((tiflags & TH_ACK) && |
953 | (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && | |
8e65fd66 | 954 | (SEQ_LT(tp->snd_wl2, ti->ti_ack) || |
bbaaf0fd | 955 | tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd))) { |
96c50630 MK |
956 | /* keep track of pure window updates */ |
957 | if (ti->ti_len == 0 && | |
386369f5 | 958 | tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd) |
96c50630 | 959 | tcpstat.tcps_rcvwinupd++; |
4aed14e3 BJ |
960 | tp->snd_wnd = ti->ti_win; |
961 | tp->snd_wl1 = ti->ti_seq; | |
962 | tp->snd_wl2 = ti->ti_ack; | |
18a438b6 MK |
963 | if (tp->snd_wnd > tp->max_sndwnd) |
964 | tp->max_sndwnd = tp->snd_wnd; | |
91039e49 MK |
965 | needoutput = 1; |
966 | } | |
4aed14e3 | 967 | |
2ff61f9d | 968 | /* |
b2db9217 | 969 | * Process segments with URG. |
2ff61f9d | 970 | */ |
9c811062 BJ |
971 | if ((tiflags & TH_URG) && ti->ti_urp && |
972 | TCPS_HAVERCVDFIN(tp->t_state) == 0) { | |
f4be5024 | 973 | /* |
bbaaf0fd | 974 | * This is a kludge, but if we receive and accept |
a5d9c993 SL |
975 | * random urgent pointers, we'll crash in |
976 | * soreceive. It's hard to imagine someone | |
977 | * actually wanting to send this much urgent data. | |
f4be5024 | 978 | */ |
2f4f574f | 979 | if (ti->ti_urp + so->so_rcv.sb_cc > SB_MAX) { |
f4be5024 SL |
980 | ti->ti_urp = 0; /* XXX */ |
981 | tiflags &= ~TH_URG; /* XXX */ | |
bbaaf0fd | 982 | goto dodata; /* XXX */ |
f4be5024 | 983 | } |
b2db9217 BJ |
984 | /* |
985 | * If this segment advances the known urgent pointer, | |
986 | * then mark the data stream. This should not happen | |
987 | * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since | |
988 | * a FIN has been received from the remote side. | |
989 | * In these states we ignore the URG. | |
ae6760c5 MK |
990 | * |
991 | * According to RFC961 (Assigned Protocols), | |
992 | * the urgent pointer points to the last octet | |
993 | * of urgent data. We continue, however, | |
994 | * to consider it to indicate the first octet | |
995 | * of data past the urgent section | |
996 | * as the original spec states. | |
b2db9217 BJ |
997 | */ |
998 | if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { | |
999 | tp->rcv_up = ti->ti_seq + ti->ti_urp; | |
1000 | so->so_oobmark = so->so_rcv.sb_cc + | |
1001 | (tp->rcv_up - tp->rcv_nxt) - 1; | |
1002 | if (so->so_oobmark == 0) | |
1003 | so->so_state |= SS_RCVATMARK; | |
77a4e3ca | 1004 | sohasoutofband(so); |
a17510f3 | 1005 | tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); |
b2db9217 BJ |
1006 | } |
1007 | /* | |
1008 | * Remove out of band data so doesn't get presented to user. | |
1009 | * This can happen independent of advancing the URG pointer, | |
1010 | * but if two URG's are pending at once, some out-of-band | |
1011 | * data may creep in... ick. | |
1012 | */ | |
9d866d2f MK |
1013 | if (ti->ti_urp <= ti->ti_len |
1014 | #ifdef SO_OOBINLINE | |
1015 | && (so->so_options & SO_OOBINLINE) == 0 | |
1016 | #endif | |
1017 | ) | |
b2db9217 | 1018 | tcp_pulloutofband(so, ti); |
bbaaf0fd MK |
1019 | } else |
1020 | /* | |
1021 | * If no out of band data is expected, | |
1022 | * pull receive urgent pointer along | |
1023 | * with the receive window. | |
1024 | */ | |
1025 | if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) | |
1026 | tp->rcv_up = tp->rcv_nxt; | |
1027 | dodata: /* XXX */ | |
87e78f19 BJ |
1028 | |
1029 | /* | |
2ff61f9d BJ |
1030 | * Process the segment text, merging it into the TCP sequencing queue, |
1031 | * and arranging for acknowledgment of receipt if necessary. | |
1032 | * This process logically involves adjusting tp->rcv_wnd as data | |
1033 | * is presented to the user (this happens in tcp_usrreq.c, | |
1034 | * case PRU_RCVD). If a FIN has already been received on this | |
1035 | * connection then we just ignore the text. | |
87e78f19 | 1036 | */ |
7984a662 MK |
1037 | if ((ti->ti_len || (tiflags&TH_FIN)) && |
1038 | TCPS_HAVERCVDFIN(tp->t_state) == 0) { | |
a17510f3 | 1039 | TCP_REASS(tp, ti, m, so, tiflags); |
18a438b6 MK |
1040 | /* |
1041 | * Note the amount of data that peer has sent into | |
1042 | * our window, in order to estimate the sender's | |
1043 | * buffer size. | |
1044 | */ | |
386369f5 | 1045 | len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); |
18a438b6 MK |
1046 | if (len > tp->max_rcvd) |
1047 | tp->max_rcvd = len; | |
4aed14e3 | 1048 | } else { |
2b4b57cd | 1049 | m_freem(m); |
e832edbc | 1050 | tiflags &= ~TH_FIN; |
4aed14e3 | 1051 | } |
87e78f19 BJ |
1052 | |
1053 | /* | |
e832edbc BJ |
1054 | * If FIN is received ACK the FIN and let the user know |
1055 | * that the connection is closing. | |
87e78f19 | 1056 | */ |
e832edbc | 1057 | if (tiflags & TH_FIN) { |
4aed14e3 BJ |
1058 | if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { |
1059 | socantrcvmore(so); | |
1060 | tp->t_flags |= TF_ACKNOW; | |
1061 | tp->rcv_nxt++; | |
1062 | } | |
2ff61f9d | 1063 | switch (tp->t_state) { |
87e78f19 | 1064 | |
2ff61f9d BJ |
1065 | /* |
1066 | * In SYN_RECEIVED and ESTABLISHED STATES | |
1067 | * enter the CLOSE_WAIT state. | |
53a5409e | 1068 | */ |
2ff61f9d BJ |
1069 | case TCPS_SYN_RECEIVED: |
1070 | case TCPS_ESTABLISHED: | |
1071 | tp->t_state = TCPS_CLOSE_WAIT; | |
1072 | break; | |
53a5409e | 1073 | |
2ff61f9d | 1074 | /* |
8a13b737 BJ |
1075 | * If still in FIN_WAIT_1 STATE FIN has not been acked so |
1076 | * enter the CLOSING state. | |
53a5409e | 1077 | */ |
2ff61f9d | 1078 | case TCPS_FIN_WAIT_1: |
8a13b737 | 1079 | tp->t_state = TCPS_CLOSING; |
2ff61f9d | 1080 | break; |
87e78f19 | 1081 | |
2ff61f9d BJ |
1082 | /* |
1083 | * In FIN_WAIT_2 state enter the TIME_WAIT state, | |
1084 | * starting the time-wait timer, turning off the other | |
1085 | * standard timers. | |
1086 | */ | |
1087 | case TCPS_FIN_WAIT_2: | |
4aed14e3 | 1088 | tp->t_state = TCPS_TIME_WAIT; |
a6503abf | 1089 | tcp_canceltimers(tp); |
405c9168 | 1090 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
4aed14e3 | 1091 | soisdisconnected(so); |
2ff61f9d BJ |
1092 | break; |
1093 | ||
53a5409e | 1094 | /* |
2ff61f9d | 1095 | * In TIME_WAIT state restart the 2 MSL time_wait timer. |
53a5409e | 1096 | */ |
2ff61f9d | 1097 | case TCPS_TIME_WAIT: |
405c9168 | 1098 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 1099 | break; |
8a13b737 | 1100 | } |
87e78f19 | 1101 | } |
4b935108 BJ |
1102 | if (so->so_options & SO_DEBUG) |
1103 | tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); | |
8a13b737 BJ |
1104 | |
1105 | /* | |
1106 | * Return any desired output. | |
1107 | */ | |
91039e49 | 1108 | if (needoutput || (tp->t_flags & TF_ACKNOW)) |
bbaaf0fd | 1109 | (void) tcp_output(tp); |
2ff61f9d | 1110 | return; |
8a13b737 | 1111 | |
2ff61f9d | 1112 | dropafterack: |
8a13b737 | 1113 | /* |
1e977657 BJ |
1114 | * Generate an ACK dropping incoming segment if it occupies |
1115 | * sequence space, where the ACK reflects our state. | |
8a13b737 | 1116 | */ |
ad616704 | 1117 | if (tiflags & TH_RST) |
8a13b737 | 1118 | goto drop; |
5722bd39 | 1119 | m_freem(m); |
4859921b MK |
1120 | tp->t_flags |= TF_ACKNOW; |
1121 | (void) tcp_output(tp); | |
4b6b94ca | 1122 | return; |
8a13b737 BJ |
1123 | |
1124 | dropwithreset: | |
f37c1c84 | 1125 | if (om) { |
668cc26d | 1126 | (void) m_free(om); |
f37c1c84 SL |
1127 | om = 0; |
1128 | } | |
8a13b737 | 1129 | /* |
4aed14e3 | 1130 | * Generate a RST, dropping incoming segment. |
8a13b737 | 1131 | * Make ACK acceptable to originator of segment. |
224f3a72 | 1132 | * Don't bother to respond if destination was broadcast. |
8a13b737 | 1133 | */ |
224f3a72 | 1134 | if ((tiflags & TH_RST) || in_broadcast(ti->ti_dst)) |
8a13b737 BJ |
1135 | goto drop; |
1136 | if (tiflags & TH_ACK) | |
8e65fd66 | 1137 | tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); |
8a13b737 BJ |
1138 | else { |
1139 | if (tiflags & TH_SYN) | |
1140 | ti->ti_len++; | |
1e977657 BJ |
1141 | tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, |
1142 | TH_RST|TH_ACK); | |
8a13b737 | 1143 | } |
7aa16f99 SL |
1144 | /* destroy temporarily created socket */ |
1145 | if (dropsocket) | |
1146 | (void) soabort(so); | |
4b6b94ca | 1147 | return; |
8a13b737 | 1148 | |
2ff61f9d | 1149 | drop: |
01b1394e SL |
1150 | if (om) |
1151 | (void) m_free(om); | |
8a13b737 BJ |
1152 | /* |
1153 | * Drop space held by incoming segment and return. | |
1154 | */ | |
f3cdd721 BJ |
1155 | if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) |
1156 | tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); | |
2ff61f9d | 1157 | m_freem(m); |
7aa16f99 SL |
1158 | /* destroy temporarily created socket */ |
1159 | if (dropsocket) | |
1160 | (void) soabort(so); | |
4b935108 | 1161 | return; |
2ff61f9d BJ |
1162 | } |
1163 | ||
99578149 | 1164 | tcp_dooptions(tp, om, ti) |
8b5a83bb BJ |
1165 | struct tcpcb *tp; |
1166 | struct mbuf *om; | |
99578149 | 1167 | struct tcpiphdr *ti; |
5e74df82 | 1168 | { |
8b5a83bb BJ |
1169 | register u_char *cp; |
1170 | int opt, optlen, cnt; | |
1171 | ||
1172 | cp = mtod(om, u_char *); | |
1173 | cnt = om->m_len; | |
1174 | for (; cnt > 0; cnt -= optlen, cp += optlen) { | |
1175 | opt = cp[0]; | |
1176 | if (opt == TCPOPT_EOL) | |
1177 | break; | |
1178 | if (opt == TCPOPT_NOP) | |
1179 | optlen = 1; | |
357b20fc | 1180 | else { |
8b5a83bb | 1181 | optlen = cp[1]; |
357b20fc SL |
1182 | if (optlen <= 0) |
1183 | break; | |
1184 | } | |
8b5a83bb BJ |
1185 | switch (opt) { |
1186 | ||
1187 | default: | |
1188 | break; | |
1189 | ||
1190 | case TCPOPT_MAXSEG: | |
1191 | if (optlen != 4) | |
1192 | continue; | |
99578149 MK |
1193 | if (!(ti->ti_flags & TH_SYN)) |
1194 | continue; | |
8b5a83bb | 1195 | tp->t_maxseg = *(u_short *)(cp + 2); |
668cc26d | 1196 | tp->t_maxseg = ntohs((u_short)tp->t_maxseg); |
99578149 | 1197 | tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp)); |
8b5a83bb | 1198 | break; |
8b5a83bb | 1199 | } |
5e74df82 | 1200 | } |
668cc26d | 1201 | (void) m_free(om); |
5e74df82 BJ |
1202 | } |
1203 | ||
b2db9217 BJ |
1204 | /* |
1205 | * Pull out of band byte out of a segment so | |
1206 | * it doesn't appear in the user's data queue. | |
1207 | * It is still reflected in the segment length for | |
1208 | * sequencing purposes. | |
1209 | */ | |
1210 | tcp_pulloutofband(so, ti) | |
1211 | struct socket *so; | |
1212 | struct tcpiphdr *ti; | |
1213 | { | |
1214 | register struct mbuf *m; | |
1acff8ec | 1215 | int cnt = ti->ti_urp - 1; |
b2db9217 BJ |
1216 | |
1217 | m = dtom(ti); | |
1218 | while (cnt >= 0) { | |
1219 | if (m->m_len > cnt) { | |
1220 | char *cp = mtod(m, caddr_t) + cnt; | |
1221 | struct tcpcb *tp = sototcpcb(so); | |
1222 | ||
1223 | tp->t_iobc = *cp; | |
1224 | tp->t_oobflags |= TCPOOB_HAVEDATA; | |
668cc26d | 1225 | bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); |
b2db9217 BJ |
1226 | m->m_len--; |
1227 | return; | |
1228 | } | |
1229 | cnt -= m->m_len; | |
1230 | m = m->m_next; | |
1231 | if (m == 0) | |
1232 | break; | |
1233 | } | |
1234 | panic("tcp_pulloutofband"); | |
1235 | } | |
1236 | ||
99578149 MK |
1237 | /* |
1238 | * Determine a reasonable value for maxseg size. | |
1239 | * If the route is known, use one that can be handled | |
1240 | * on the given interface without forcing IP to fragment. | |
7cc62c26 MK |
1241 | * If bigger than an mbuf cluster (MCLBYTES), round down to nearest size |
1242 | * to utilize large mbufs. | |
99578149 | 1243 | * If interface pointer is unavailable, or the destination isn't local, |
c2a1cd2c MK |
1244 | * use a conservative size (512 or the default IP max size, but no more |
1245 | * than the mtu of the interface through which we route), | |
99578149 | 1246 | * as we can't discover anything about intervening gateways or networks. |
a6bbda13 MK |
1247 | * We also initialize the congestion/slow start window to be a single |
1248 | * segment if the destination isn't local; this information should | |
1249 | * probably all be saved with the routing entry at the transport level. | |
99578149 MK |
1250 | * |
1251 | * This is ugly, and doesn't belong at this level, but has to happen somehow. | |
1252 | */ | |
1253 | tcp_mss(tp) | |
c2a1cd2c | 1254 | register struct tcpcb *tp; |
99578149 MK |
1255 | { |
1256 | struct route *ro; | |
1257 | struct ifnet *ifp; | |
1258 | int mss; | |
1259 | struct inpcb *inp; | |
1260 | ||
1261 | inp = tp->t_inpcb; | |
1262 | ro = &inp->inp_route; | |
1263 | if ((ro->ro_rt == (struct rtentry *)0) || | |
1264 | (ifp = ro->ro_rt->rt_ifp) == (struct ifnet *)0) { | |
1265 | /* No route yet, so try to acquire one */ | |
1266 | if (inp->inp_faddr.s_addr != INADDR_ANY) { | |
1267 | ro->ro_dst.sa_family = AF_INET; | |
1268 | ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = | |
1269 | inp->inp_faddr; | |
1270 | rtalloc(ro); | |
1271 | } | |
1272 | if ((ro->ro_rt == 0) || (ifp = ro->ro_rt->rt_ifp) == 0) | |
0d115dcc | 1273 | return (TCP_MSS); |
99578149 MK |
1274 | } |
1275 | ||
1276 | mss = ifp->if_mtu - sizeof(struct tcpiphdr); | |
7cc62c26 MK |
1277 | #if (MCLBYTES & (MCLBYTES - 1)) == 0 |
1278 | if (mss > MCLBYTES) | |
1279 | mss &= ~(MCLBYTES-1); | |
99578149 | 1280 | #else |
7cc62c26 MK |
1281 | if (mss > MCLBYTES) |
1282 | mss = mss / MCLBYTES * MCLBYTES; | |
99578149 | 1283 | #endif |
c2a1cd2c MK |
1284 | if (in_localaddr(inp->inp_faddr)) |
1285 | return (mss); | |
386369f5 | 1286 | |
a6bbda13 MK |
1287 | mss = MIN(mss, TCP_MSS); |
1288 | tp->snd_cwnd = mss; | |
1289 | return (mss); | |
99578149 | 1290 | } |
9d866d2f MK |
1291 | |
1292 | #if BSD<43 | |
1293 | /* XXX this belongs in netinet/in.c */ | |
1294 | in_localaddr(in) | |
1295 | struct in_addr in; | |
1296 | { | |
1297 | register u_long i = ntohl(in.s_addr); | |
1298 | register struct ifnet *ifp; | |
1299 | register struct sockaddr_in *sin; | |
1300 | register u_long mask; | |
1301 | ||
1302 | if (IN_CLASSA(i)) | |
1303 | mask = IN_CLASSA_NET; | |
1304 | else if (IN_CLASSB(i)) | |
1305 | mask = IN_CLASSB_NET; | |
1306 | else if (IN_CLASSC(i)) | |
1307 | mask = IN_CLASSC_NET; | |
1308 | else | |
1309 | return (0); | |
1310 | ||
1311 | i &= mask; | |
1312 | for (ifp = ifnet; ifp; ifp = ifp->if_next) { | |
1313 | if (ifp->if_addr.sa_family != AF_INET) | |
1314 | continue; | |
1315 | sin = (struct sockaddr_in *)&ifp->if_addr; | |
1316 | if ((sin->sin_addr.s_addr & mask) == i) | |
1317 | return (1); | |
1318 | } | |
1319 | return (0); | |
1320 | } | |
1321 | #endif |