Commit | Line | Data |
---|---|---|
8ae0e4b4 | 1 | /* |
0880b18e | 2 | * Copyright (c) 1982, 1986 Regents of the University of California. |
8ae0e4b4 KM |
3 | * All rights reserved. The Berkeley software License Agreement |
4 | * specifies the terms and conditions for redistribution. | |
5 | * | |
0880b18e | 6 | * @(#)tcp_input.c 7.1 (Berkeley) %G% |
8ae0e4b4 | 7 | */ |
87e78f19 | 8 | |
20666ad3 JB |
9 | #include "param.h" |
10 | #include "systm.h" | |
11 | #include "mbuf.h" | |
12 | #include "protosw.h" | |
13 | #include "socket.h" | |
14 | #include "socketvar.h" | |
15 | #include "errno.h" | |
f4d55810 SL |
16 | |
17 | #include "../net/if.h" | |
c124e997 | 18 | #include "../net/route.h" |
f4d55810 | 19 | |
20666ad3 JB |
20 | #include "in.h" |
21 | #include "in_pcb.h" | |
22 | #include "in_systm.h" | |
23 | #include "ip.h" | |
24 | #include "ip_var.h" | |
25 | #include "tcp.h" | |
26 | #include "tcp_fsm.h" | |
27 | #include "tcp_seq.h" | |
28 | #include "tcp_timer.h" | |
29 | #include "tcp_var.h" | |
30 | #include "tcpip.h" | |
31 | #include "tcp_debug.h" | |
87e78f19 | 32 | |
22856bb8 | 33 | int tcpprintfs = 0; |
60b16fa9 | 34 | int tcpcksum = 1; |
4b935108 | 35 | struct tcpiphdr tcp_saveti; |
8b5a83bb | 36 | extern tcpnodelack; |
87e78f19 | 37 | |
4b935108 | 38 | struct tcpcb *tcp_newtcpcb(); |
a17510f3 MK |
39 | |
40 | /* | |
41 | * Insert segment ti into reassembly queue of tcp with | |
42 | * control block tp. Return TH_FIN if reassembly now includes | |
43 | * a segment with FIN. The macro form does the common case inline | |
44 | * (segment is the next to be received on an established connection, | |
45 | * and the queue is empty), avoiding linkage into and removal | |
46 | * from the queue and repetition of various conversions. | |
47 | */ | |
48 | #define TCP_REASS(tp, ti, m, so, flags) { \ | |
49 | if ((ti)->ti_seq == (tp)->rcv_nxt && \ | |
50 | (tp)->seg_next == (struct tcpiphdr *)(tp) && \ | |
51 | (tp)->t_state == TCPS_ESTABLISHED) { \ | |
52 | (tp)->rcv_nxt += (ti)->ti_len; \ | |
53 | flags = (ti)->ti_flags & TH_FIN; \ | |
54 | sbappend(&(so)->so_rcv, (m)); \ | |
55 | sorwakeup(so); \ | |
56 | } else \ | |
57 | (flags) = tcp_reass((tp), (ti)); \ | |
58 | } | |
59 | ||
60 | tcp_reass(tp, ti) | |
61 | register struct tcpcb *tp; | |
62 | register struct tcpiphdr *ti; | |
63 | { | |
64 | register struct tcpiphdr *q; | |
65 | struct socket *so = tp->t_inpcb->inp_socket; | |
66 | struct mbuf *m; | |
67 | int flags; | |
68 | ||
69 | /* | |
70 | * Call with ti==0 after become established to | |
71 | * force pre-ESTABLISHED data up to user socket. | |
72 | */ | |
73 | if (ti == 0) | |
74 | goto present; | |
75 | ||
76 | /* | |
77 | * Find a segment which begins after this one does. | |
78 | */ | |
79 | for (q = tp->seg_next; q != (struct tcpiphdr *)tp; | |
80 | q = (struct tcpiphdr *)q->ti_next) | |
81 | if (SEQ_GT(q->ti_seq, ti->ti_seq)) | |
82 | break; | |
83 | ||
84 | /* | |
85 | * If there is a preceding segment, it may provide some of | |
86 | * our data already. If so, drop the data from the incoming | |
87 | * segment. If it provides all of our data, drop us. | |
88 | */ | |
89 | if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { | |
90 | register int i; | |
91 | q = (struct tcpiphdr *)q->ti_prev; | |
92 | /* conversion to int (in i) handles seq wraparound */ | |
93 | i = q->ti_seq + q->ti_len - ti->ti_seq; | |
94 | if (i > 0) { | |
95 | if (i >= ti->ti_len) | |
96 | goto drop; | |
97 | m_adj(dtom(ti), i); | |
98 | ti->ti_len -= i; | |
99 | ti->ti_seq += i; | |
100 | } | |
101 | q = (struct tcpiphdr *)(q->ti_next); | |
102 | } | |
103 | ||
104 | /* | |
105 | * While we overlap succeeding segments trim them or, | |
106 | * if they are completely covered, dequeue them. | |
107 | */ | |
108 | while (q != (struct tcpiphdr *)tp) { | |
109 | register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; | |
110 | if (i <= 0) | |
111 | break; | |
112 | if (i < q->ti_len) { | |
113 | q->ti_seq += i; | |
114 | q->ti_len -= i; | |
115 | m_adj(dtom(q), i); | |
116 | break; | |
117 | } | |
118 | q = (struct tcpiphdr *)q->ti_next; | |
119 | m = dtom(q->ti_prev); | |
120 | remque(q->ti_prev); | |
121 | m_freem(m); | |
122 | } | |
123 | ||
124 | /* | |
125 | * Stick new segment in its place. | |
126 | */ | |
127 | insque(ti, q->ti_prev); | |
128 | ||
129 | present: | |
130 | /* | |
131 | * Present data to user, advancing rcv_nxt through | |
132 | * completed sequence space. | |
133 | */ | |
134 | if (TCPS_HAVERCVDSYN(tp->t_state) == 0) | |
135 | return (0); | |
136 | ti = tp->seg_next; | |
137 | if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) | |
138 | return (0); | |
139 | if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) | |
140 | return (0); | |
141 | do { | |
142 | tp->rcv_nxt += ti->ti_len; | |
143 | flags = ti->ti_flags & TH_FIN; | |
144 | remque(ti); | |
145 | m = dtom(ti); | |
146 | ti = (struct tcpiphdr *)ti->ti_next; | |
147 | if (so->so_state & SS_CANTRCVMORE) | |
148 | m_freem(m); | |
149 | else | |
150 | sbappend(&so->so_rcv, m); | |
151 | } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); | |
152 | sorwakeup(so); | |
153 | return (flags); | |
154 | drop: | |
155 | m_freem(dtom(ti)); | |
156 | return (0); | |
157 | } | |
158 | ||
2ff61f9d BJ |
159 | /* |
160 | * TCP input routine, follows pages 65-76 of the | |
161 | * protocol specification dated September, 1981 very closely. | |
162 | */ | |
2b4b57cd BJ |
163 | tcp_input(m0) |
164 | struct mbuf *m0; | |
87e78f19 | 165 | { |
2b4b57cd | 166 | register struct tcpiphdr *ti; |
53a5409e | 167 | struct inpcb *inp; |
2b4b57cd | 168 | register struct mbuf *m; |
8b5a83bb | 169 | struct mbuf *om = 0; |
2b4b57cd | 170 | int len, tlen, off; |
8e65fd66 | 171 | register struct tcpcb *tp = 0; |
2b4b57cd | 172 | register int tiflags; |
d52566dd | 173 | struct socket *so; |
91039e49 | 174 | int todrop, acked, needoutput = 0; |
4b935108 | 175 | short ostate; |
ebcadd38 | 176 | struct in_addr laddr; |
7aa16f99 | 177 | int dropsocket = 0; |
87e78f19 BJ |
178 | |
179 | /* | |
4aed14e3 BJ |
180 | * Get IP and TCP header together in first mbuf. |
181 | * Note: IP leaves IP header in first mbuf. | |
87e78f19 | 182 | */ |
2b4b57cd | 183 | m = m0; |
20790db4 | 184 | ti = mtod(m, struct tcpiphdr *); |
4aed14e3 | 185 | if (((struct ip *)ti)->ip_hl > (sizeof (struct ip) >> 2)) |
d63599ac | 186 | ip_stripoptions((struct ip *)ti, (struct mbuf *)0); |
6703c41f BJ |
187 | if (m->m_off > MMAXOFF || m->m_len < sizeof (struct tcpiphdr)) { |
188 | if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) { | |
8a13b737 | 189 | tcpstat.tcps_hdrops++; |
6703c41f | 190 | return; |
8a13b737 BJ |
191 | } |
192 | ti = mtod(m, struct tcpiphdr *); | |
193 | } | |
87e78f19 | 194 | |
2b4b57cd | 195 | /* |
4aed14e3 | 196 | * Checksum extended TCP header and data. |
2b4b57cd BJ |
197 | */ |
198 | tlen = ((struct ip *)ti)->ip_len; | |
199 | len = sizeof (struct ip) + tlen; | |
60b16fa9 | 200 | if (tcpcksum) { |
2b4b57cd BJ |
201 | ti->ti_next = ti->ti_prev = 0; |
202 | ti->ti_x1 = 0; | |
ac83b17a | 203 | ti->ti_len = (u_short)tlen; |
668cc26d | 204 | ti->ti_len = htons((u_short)ti->ti_len); |
4b6b94ca | 205 | if (ti->ti_sum = in_cksum(m, len)) { |
ee954ff1 SL |
206 | if (tcpprintfs) |
207 | printf("tcp sum: src %x\n", ti->ti_src); | |
2b4b57cd | 208 | tcpstat.tcps_badsum++; |
8a13b737 | 209 | goto drop; |
87e78f19 BJ |
210 | } |
211 | } | |
212 | ||
213 | /* | |
4aed14e3 | 214 | * Check that TCP offset makes sense, |
8b5a83bb | 215 | * pull out TCP options and adjust length. |
87e78f19 | 216 | */ |
2b4b57cd | 217 | off = ti->ti_off << 2; |
4b6b94ca | 218 | if (off < sizeof (struct tcphdr) || off > tlen) { |
ee954ff1 SL |
219 | if (tcpprintfs) |
220 | printf("tcp off: src %x off %d\n", ti->ti_src, off); | |
2b4b57cd | 221 | tcpstat.tcps_badoff++; |
8a13b737 | 222 | goto drop; |
2b4b57cd | 223 | } |
1e977657 BJ |
224 | tlen -= off; |
225 | ti->ti_len = tlen; | |
8b5a83bb | 226 | if (off > sizeof (struct tcphdr)) { |
a17510f3 MK |
227 | if (m->m_len < sizeof(struct ip) + off) { |
228 | if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) { | |
229 | tcpstat.tcps_hdrops++; | |
230 | return; | |
231 | } | |
232 | ti = mtod(m, struct tcpiphdr *); | |
8b5a83bb | 233 | } |
cce93e4b | 234 | om = m_get(M_DONTWAIT, MT_DATA); |
8b5a83bb BJ |
235 | if (om == 0) |
236 | goto drop; | |
8b5a83bb BJ |
237 | om->m_len = off - sizeof (struct tcphdr); |
238 | { caddr_t op = mtod(m, caddr_t) + sizeof (struct tcpiphdr); | |
668cc26d | 239 | bcopy(op, mtod(om, caddr_t), (unsigned)om->m_len); |
8b5a83bb | 240 | m->m_len -= om->m_len; |
668cc26d SL |
241 | bcopy(op+om->m_len, op, |
242 | (unsigned)(m->m_len-sizeof (struct tcpiphdr))); | |
8b5a83bb BJ |
243 | } |
244 | } | |
2ff61f9d | 245 | tiflags = ti->ti_flags; |
2b4b57cd | 246 | |
795e0416 | 247 | /* |
669abecf | 248 | * Drop TCP and IP headers; TCP options were dropped above. |
795e0416 | 249 | */ |
669abecf KM |
250 | m->m_off += sizeof(struct tcpiphdr); |
251 | m->m_len -= sizeof(struct tcpiphdr); | |
795e0416 | 252 | |
8a13b737 | 253 | /* |
4aed14e3 | 254 | * Convert TCP protocol specific fields to host format. |
8a13b737 BJ |
255 | */ |
256 | ti->ti_seq = ntohl(ti->ti_seq); | |
257 | ti->ti_ack = ntohl(ti->ti_ack); | |
258 | ti->ti_win = ntohs(ti->ti_win); | |
259 | ti->ti_urp = ntohs(ti->ti_urp); | |
260 | ||
2b4b57cd | 261 | /* |
8075bb0e | 262 | * Locate pcb for segment. |
2b4b57cd | 263 | */ |
2ff61f9d | 264 | inp = in_pcblookup |
ebcadd38 BJ |
265 | (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport, |
266 | INPLOOKUP_WILDCARD); | |
2ff61f9d BJ |
267 | |
268 | /* | |
269 | * If the state is CLOSED (i.e., TCB does not exist) then | |
4aed14e3 | 270 | * all data in the incoming segment is discarded. |
2ff61f9d | 271 | */ |
22856bb8 | 272 | if (inp == 0) |
8a13b737 | 273 | goto dropwithreset; |
2ff61f9d | 274 | tp = intotcpcb(inp); |
22856bb8 | 275 | if (tp == 0) |
8a13b737 | 276 | goto dropwithreset; |
f1b2fa5b | 277 | so = inp->inp_socket; |
4b935108 BJ |
278 | if (so->so_options & SO_DEBUG) { |
279 | ostate = tp->t_state; | |
280 | tcp_saveti = *ti; | |
281 | } | |
ebf42a75 BJ |
282 | if (so->so_options & SO_ACCEPTCONN) { |
283 | so = sonewconn(so); | |
284 | if (so == 0) | |
285 | goto drop; | |
7aa16f99 SL |
286 | /* |
287 | * This is ugly, but .... | |
288 | * | |
289 | * Mark socket as temporary until we're | |
290 | * committed to keeping it. The code at | |
291 | * ``drop'' and ``dropwithreset'' check the | |
292 | * flag dropsocket to see if the temporary | |
293 | * socket created here should be discarded. | |
294 | * We mark the socket as discardable until | |
295 | * we're committed to it below in TCPS_LISTEN. | |
296 | */ | |
297 | dropsocket++; | |
ebf42a75 BJ |
298 | inp = (struct inpcb *)so->so_pcb; |
299 | inp->inp_laddr = ti->ti_dst; | |
300 | inp->inp_lport = ti->ti_dport; | |
a17510f3 | 301 | inp->inp_options = ip_srcroute(); |
ebf42a75 BJ |
302 | tp = intotcpcb(inp); |
303 | tp->t_state = TCPS_LISTEN; | |
304 | } | |
87e78f19 | 305 | |
405c9168 BJ |
306 | /* |
307 | * Segment received on connection. | |
308 | * Reset idle time and keep-alive timer. | |
309 | */ | |
310 | tp->t_idle = 0; | |
311 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; | |
312 | ||
8b5a83bb | 313 | /* |
99578149 MK |
314 | * Process options if not in LISTEN state, |
315 | * else do it below (after getting remote address). | |
8b5a83bb | 316 | */ |
99578149 MK |
317 | if (om && tp->t_state != TCPS_LISTEN) { |
318 | tcp_dooptions(tp, om, ti); | |
8b5a83bb BJ |
319 | om = 0; |
320 | } | |
321 | ||
87e78f19 | 322 | /* |
8a13b737 BJ |
323 | * Calculate amount of space in receive window, |
324 | * and then do TCP input processing. | |
a17510f3 MK |
325 | * Receive window is amount of space in rcv queue, |
326 | * but not less than advertised window. | |
87e78f19 | 327 | */ |
bbaaf0fd MK |
328 | { int win; |
329 | ||
330 | win = sbspace(&so->so_rcv); | |
331 | if (win < 0) | |
332 | win = 0; | |
333 | tp->rcv_wnd = MAX(win, (int)(tp->rcv_adv - tp->rcv_nxt)); | |
334 | } | |
2ff61f9d | 335 | |
87e78f19 BJ |
336 | switch (tp->t_state) { |
337 | ||
2ff61f9d BJ |
338 | /* |
339 | * If the state is LISTEN then ignore segment if it contains an RST. | |
340 | * If the segment contains an ACK then it is bad and send a RST. | |
341 | * If it does not contain a SYN then it is not interesting; drop it. | |
224f3a72 | 342 | * Don't bother responding if the destination was a broadcast. |
8a13b737 | 343 | * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial |
2ff61f9d | 344 | * tp->iss, and send a segment: |
8a13b737 | 345 | * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> |
2ff61f9d BJ |
346 | * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. |
347 | * Fill in remote peer address fields if not previously specified. | |
348 | * Enter SYN_RECEIVED state, and process any other fields of this | |
4aed14e3 | 349 | * segment in this state. |
2ff61f9d | 350 | */ |
8075bb0e | 351 | case TCPS_LISTEN: { |
789d2a39 | 352 | struct mbuf *am; |
8075bb0e BJ |
353 | register struct sockaddr_in *sin; |
354 | ||
2ff61f9d BJ |
355 | if (tiflags & TH_RST) |
356 | goto drop; | |
22856bb8 | 357 | if (tiflags & TH_ACK) |
8a13b737 | 358 | goto dropwithreset; |
22856bb8 | 359 | if ((tiflags & TH_SYN) == 0) |
2ff61f9d | 360 | goto drop; |
224f3a72 MK |
361 | if (in_broadcast(ti->ti_dst)) |
362 | goto drop; | |
789d2a39 SL |
363 | am = m_get(M_DONTWAIT, MT_SONAME); |
364 | if (am == NULL) | |
365 | goto drop; | |
366 | am->m_len = sizeof (struct sockaddr_in); | |
a8d3bf7f | 367 | sin = mtod(am, struct sockaddr_in *); |
8075bb0e BJ |
368 | sin->sin_family = AF_INET; |
369 | sin->sin_addr = ti->ti_src; | |
370 | sin->sin_port = ti->ti_sport; | |
ebcadd38 | 371 | laddr = inp->inp_laddr; |
789d2a39 | 372 | if (inp->inp_laddr.s_addr == INADDR_ANY) |
ebcadd38 | 373 | inp->inp_laddr = ti->ti_dst; |
a8d3bf7f | 374 | if (in_pcbconnect(inp, am)) { |
ebcadd38 | 375 | inp->inp_laddr = laddr; |
5a1f132a | 376 | (void) m_free(am); |
4aed14e3 | 377 | goto drop; |
ebcadd38 | 378 | } |
5a1f132a | 379 | (void) m_free(am); |
4aed14e3 BJ |
380 | tp->t_template = tcp_template(tp); |
381 | if (tp->t_template == 0) { | |
8011f5df | 382 | tp = tcp_drop(tp, ENOBUFS); |
a4f7ea71 | 383 | dropsocket = 0; /* socket is already gone */ |
4aed14e3 BJ |
384 | goto drop; |
385 | } | |
99578149 MK |
386 | if (om) { |
387 | tcp_dooptions(tp, om, ti); | |
388 | om = 0; | |
389 | } | |
8a13b737 | 390 | tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; |
2ff61f9d | 391 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
392 | tcp_sendseqinit(tp); |
393 | tcp_rcvseqinit(tp); | |
bbaaf0fd | 394 | tp->t_flags |= TF_ACKNOW; |
2ff61f9d | 395 | tp->t_state = TCPS_SYN_RECEIVED; |
4aed14e3 | 396 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; |
7aa16f99 | 397 | dropsocket = 0; /* committed to socket */ |
8a13b737 | 398 | goto trimthenstep6; |
8075bb0e | 399 | } |
87e78f19 | 400 | |
2ff61f9d BJ |
401 | /* |
402 | * If the state is SYN_SENT: | |
403 | * if seg contains an ACK, but not for our SYN, drop the input. | |
404 | * if seg contains a RST, then drop the connection. | |
405 | * if seg does not contain SYN, then drop it. | |
406 | * Otherwise this is an acceptable SYN segment | |
407 | * initialize tp->rcv_nxt and tp->irs | |
408 | * if seg contains ack then advance tp->snd_una | |
409 | * if SYN has been acked change to ESTABLISHED else SYN_RCVD state | |
410 | * arrange for segment to be acked (eventually) | |
411 | * continue processing rest of data/controls, beginning with URG | |
412 | */ | |
413 | case TCPS_SYN_SENT: | |
414 | if ((tiflags & TH_ACK) && | |
a17510f3 | 415 | (SEQ_LEQ(ti->ti_ack, tp->iss) || |
4b6b94ca | 416 | SEQ_GT(ti->ti_ack, tp->snd_max))) |
8a13b737 | 417 | goto dropwithreset; |
2ff61f9d | 418 | if (tiflags & TH_RST) { |
0e3936fa SL |
419 | if (tiflags & TH_ACK) |
420 | tp = tcp_drop(tp, ECONNREFUSED); | |
2ff61f9d | 421 | goto drop; |
87e78f19 | 422 | } |
2ff61f9d BJ |
423 | if ((tiflags & TH_SYN) == 0) |
424 | goto drop; | |
4b6b94ca | 425 | tp->snd_una = ti->ti_ack; |
b8977237 BJ |
426 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
427 | tp->snd_nxt = tp->snd_una; | |
4aed14e3 | 428 | tp->t_timer[TCPT_REXMT] = 0; |
2ff61f9d | 429 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
430 | tcp_rcvseqinit(tp); |
431 | tp->t_flags |= TF_ACKNOW; | |
405c9168 | 432 | if (SEQ_GT(tp->snd_una, tp->iss)) { |
4aed14e3 | 433 | soisconnected(so); |
2ff61f9d | 434 | tp->t_state = TCPS_ESTABLISHED; |
99578149 | 435 | tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp)); |
405c9168 BJ |
436 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
437 | } else | |
8a13b737 BJ |
438 | tp->t_state = TCPS_SYN_RECEIVED; |
439 | goto trimthenstep6; | |
440 | ||
441 | trimthenstep6: | |
442 | /* | |
4b6b94ca | 443 | * Advance ti->ti_seq to correspond to first data byte. |
8a13b737 BJ |
444 | * If data, trim to stay within window, |
445 | * dropping FIN if necessary. | |
446 | */ | |
4b6b94ca | 447 | ti->ti_seq++; |
8a13b737 BJ |
448 | if (ti->ti_len > tp->rcv_wnd) { |
449 | todrop = ti->ti_len - tp->rcv_wnd; | |
450 | m_adj(m, -todrop); | |
451 | ti->ti_len = tp->rcv_wnd; | |
bbaaf0fd | 452 | tiflags &= ~TH_FIN; |
87e78f19 | 453 | } |
e832edbc | 454 | tp->snd_wl1 = ti->ti_seq - 1; |
bbaaf0fd | 455 | tp->rcv_up = ti->ti_seq; |
8a13b737 | 456 | goto step6; |
2ff61f9d | 457 | } |
87e78f19 | 458 | |
ed6315dd MK |
459 | /* |
460 | * If data is received on a connection after the | |
461 | * user processes are gone, then RST the other end. | |
462 | */ | |
463 | if ((so->so_state & SS_NOFDREF) && tp->t_state > TCPS_CLOSE_WAIT && | |
464 | ti->ti_len) { | |
465 | tp = tcp_close(tp); | |
466 | goto dropwithreset; | |
467 | } | |
468 | ||
2ff61f9d BJ |
469 | /* |
470 | * States other than LISTEN or SYN_SENT. | |
471 | * First check that at least some bytes of segment are within | |
472 | * receive window. | |
473 | */ | |
474 | if (tp->rcv_wnd == 0) { | |
475 | /* | |
476 | * If window is closed can only take segments at | |
4b6b94ca | 477 | * window edge, and have to drop data and PUSH from |
2ff61f9d BJ |
478 | * incoming segments. |
479 | */ | |
22856bb8 | 480 | if (tp->rcv_nxt != ti->ti_seq) |
2ff61f9d | 481 | goto dropafterack; |
8a13b737 | 482 | if (ti->ti_len > 0) { |
fd5dc5f0 | 483 | m_adj(m, ti->ti_len); |
8a13b737 | 484 | ti->ti_len = 0; |
bbaaf0fd | 485 | tiflags &= ~(TH_PUSH|TH_FIN); |
87e78f19 | 486 | } |
2ff61f9d BJ |
487 | } else { |
488 | /* | |
4b6b94ca | 489 | * If segment begins before rcv_nxt, drop leading |
2ff61f9d BJ |
490 | * data (and SYN); if nothing left, just ack. |
491 | */ | |
fd5dc5f0 BJ |
492 | todrop = tp->rcv_nxt - ti->ti_seq; |
493 | if (todrop > 0) { | |
8a13b737 | 494 | if (tiflags & TH_SYN) { |
22856bb8 | 495 | tiflags &= ~TH_SYN; |
8a13b737 BJ |
496 | ti->ti_seq++; |
497 | if (ti->ti_urp > 1) | |
498 | ti->ti_urp--; | |
499 | else | |
500 | tiflags &= ~TH_URG; | |
501 | todrop--; | |
502 | } | |
1e977657 BJ |
503 | if (todrop > ti->ti_len || |
504 | todrop == ti->ti_len && (tiflags&TH_FIN) == 0) | |
2ff61f9d BJ |
505 | goto dropafterack; |
506 | m_adj(m, todrop); | |
507 | ti->ti_seq += todrop; | |
508 | ti->ti_len -= todrop; | |
8a13b737 BJ |
509 | if (ti->ti_urp > todrop) |
510 | ti->ti_urp -= todrop; | |
511 | else { | |
512 | tiflags &= ~TH_URG; | |
fd5dc5f0 | 513 | ti->ti_urp = 0; |
8a13b737 | 514 | } |
2ff61f9d BJ |
515 | } |
516 | /* | |
517 | * If segment ends after window, drop trailing data | |
8a13b737 | 518 | * (and PUSH and FIN); if nothing left, just ACK. |
2ff61f9d | 519 | */ |
fd5dc5f0 BJ |
520 | todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); |
521 | if (todrop > 0) { | |
1e977657 | 522 | if (todrop >= ti->ti_len) |
2ff61f9d BJ |
523 | goto dropafterack; |
524 | m_adj(m, -todrop); | |
525 | ti->ti_len -= todrop; | |
bbaaf0fd | 526 | tiflags &= ~(TH_PUSH|TH_FIN); |
87e78f19 | 527 | } |
87e78f19 | 528 | } |
87e78f19 | 529 | |
87e78f19 | 530 | /* |
2ff61f9d BJ |
531 | * If the RST bit is set examine the state: |
532 | * SYN_RECEIVED STATE: | |
533 | * If passive open, return to LISTEN state. | |
534 | * If active open, inform user that connection was refused. | |
535 | * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: | |
536 | * Inform user that connection was reset, and close tcb. | |
537 | * CLOSING, LAST_ACK, TIME_WAIT STATES | |
538 | * Close the tcb. | |
87e78f19 | 539 | */ |
2ff61f9d | 540 | if (tiflags&TH_RST) switch (tp->t_state) { |
4b935108 | 541 | |
2ff61f9d | 542 | case TCPS_SYN_RECEIVED: |
0e3936fa | 543 | tp = tcp_drop(tp, ECONNREFUSED); |
2ff61f9d BJ |
544 | goto drop; |
545 | ||
546 | case TCPS_ESTABLISHED: | |
547 | case TCPS_FIN_WAIT_1: | |
548 | case TCPS_FIN_WAIT_2: | |
549 | case TCPS_CLOSE_WAIT: | |
0e3936fa | 550 | tp = tcp_drop(tp, ECONNRESET); |
2ff61f9d BJ |
551 | goto drop; |
552 | ||
553 | case TCPS_CLOSING: | |
554 | case TCPS_LAST_ACK: | |
555 | case TCPS_TIME_WAIT: | |
0e3936fa | 556 | tp = tcp_close(tp); |
2ff61f9d | 557 | goto drop; |
87e78f19 | 558 | } |
87e78f19 BJ |
559 | |
560 | /* | |
2ff61f9d BJ |
561 | * If a SYN is in the window, then this is an |
562 | * error and we send an RST and drop the connection. | |
563 | */ | |
564 | if (tiflags & TH_SYN) { | |
0e3936fa | 565 | tp = tcp_drop(tp, ECONNRESET); |
8a13b737 | 566 | goto dropwithreset; |
2ff61f9d BJ |
567 | } |
568 | ||
569 | /* | |
570 | * If the ACK bit is off we drop the segment and return. | |
571 | */ | |
8a13b737 | 572 | if ((tiflags & TH_ACK) == 0) |
2ff61f9d BJ |
573 | goto drop; |
574 | ||
575 | /* | |
576 | * Ack processing. | |
87e78f19 | 577 | */ |
87e78f19 BJ |
578 | switch (tp->t_state) { |
579 | ||
2ff61f9d BJ |
580 | /* |
581 | * In SYN_RECEIVED state if the ack ACKs our SYN then enter | |
582 | * ESTABLISHED state and continue processing, othewise | |
583 | * send an RST. | |
584 | */ | |
585 | case TCPS_SYN_RECEIVED: | |
8a13b737 | 586 | if (SEQ_GT(tp->snd_una, ti->ti_ack) || |
4b6b94ca | 587 | SEQ_GT(ti->ti_ack, tp->snd_max)) |
8a13b737 | 588 | goto dropwithreset; |
4aed14e3 | 589 | tp->snd_una++; /* SYN acked */ |
b8977237 BJ |
590 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
591 | tp->snd_nxt = tp->snd_una; | |
4aed14e3 | 592 | tp->t_timer[TCPT_REXMT] = 0; |
8a13b737 BJ |
593 | soisconnected(so); |
594 | tp->t_state = TCPS_ESTABLISHED; | |
99578149 | 595 | tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp)); |
405c9168 | 596 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
4aed14e3 | 597 | tp->snd_wl1 = ti->ti_seq - 1; |
8a13b737 | 598 | /* fall into ... */ |
87e78f19 | 599 | |
2ff61f9d BJ |
600 | /* |
601 | * In ESTABLISHED state: drop duplicate ACKs; ACK out of range | |
602 | * ACKs. If the ack is in the range | |
4b6b94ca | 603 | * tp->snd_una < ti->ti_ack <= tp->snd_max |
2ff61f9d BJ |
604 | * then advance tp->snd_una to ti->ti_ack and drop |
605 | * data from the retransmission queue. If this ACK reflects | |
606 | * more up to date window information we update our window information. | |
607 | */ | |
608 | case TCPS_ESTABLISHED: | |
609 | case TCPS_FIN_WAIT_1: | |
610 | case TCPS_FIN_WAIT_2: | |
611 | case TCPS_CLOSE_WAIT: | |
612 | case TCPS_CLOSING: | |
4aed14e3 BJ |
613 | case TCPS_LAST_ACK: |
614 | case TCPS_TIME_WAIT: | |
8a13b737 BJ |
615 | #define ourfinisacked (acked > 0) |
616 | ||
4aed14e3 | 617 | if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) |
2ff61f9d | 618 | break; |
22856bb8 | 619 | if (SEQ_GT(ti->ti_ack, tp->snd_max)) |
2ff61f9d | 620 | goto dropafterack; |
8a13b737 | 621 | acked = ti->ti_ack - tp->snd_una; |
dd020fc8 BJ |
622 | |
623 | /* | |
624 | * If transmit timer is running and timed sequence | |
625 | * number was acked, update smoothed round trip time. | |
626 | */ | |
627 | if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { | |
628 | if (tp->t_srtt == 0) | |
629 | tp->t_srtt = tp->t_rtt; | |
630 | else | |
631 | tp->t_srtt = | |
632 | tcp_alpha * tp->t_srtt + | |
633 | (1 - tcp_alpha) * tp->t_rtt; | |
dd020fc8 BJ |
634 | tp->t_rtt = 0; |
635 | } | |
636 | ||
91039e49 MK |
637 | /* |
638 | * If all outstanding data is acked, stop retransmit | |
639 | * timer and remember to restart (more output or persist). | |
640 | * If there is more data to be acked, restart retransmit | |
641 | * timer. | |
642 | */ | |
643 | if (ti->ti_ack == tp->snd_max) { | |
4aed14e3 | 644 | tp->t_timer[TCPT_REXMT] = 0; |
91039e49 MK |
645 | needoutput = 1; |
646 | } else if (tp->t_timer[TCPT_PERSIST] == 0) { | |
4aed14e3 BJ |
647 | TCPT_RANGESET(tp->t_timer[TCPT_REXMT], |
648 | tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); | |
22856bb8 | 649 | tp->t_rxtshift = 0; |
8a13b737 | 650 | } |
1e9621b8 MK |
651 | /* |
652 | * When new data is acked, open the congestion window a bit. | |
653 | */ | |
654 | if (acked > 0) | |
655 | tp->snd_cwnd = MIN(11 * tp->snd_cwnd / 10, 65535); | |
6703c41f | 656 | if (acked > so->so_snd.sb_cc) { |
6703c41f | 657 | tp->snd_wnd -= so->so_snd.sb_cc; |
8011f5df | 658 | sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); |
6703c41f | 659 | } else { |
668cc26d | 660 | sbdrop(&so->so_snd, acked); |
6703c41f BJ |
661 | tp->snd_wnd -= acked; |
662 | acked = 0; | |
663 | } | |
5744ed2b | 664 | if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel) |
22856bb8 | 665 | sowwakeup(so); |
4b6b94ca | 666 | tp->snd_una = ti->ti_ack; |
b8977237 BJ |
667 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
668 | tp->snd_nxt = tp->snd_una; | |
405c9168 | 669 | |
87e78f19 BJ |
670 | switch (tp->t_state) { |
671 | ||
2ff61f9d BJ |
672 | /* |
673 | * In FIN_WAIT_1 STATE in addition to the processing | |
674 | * for the ESTABLISHED state if our FIN is now acknowledged | |
8a13b737 | 675 | * then enter FIN_WAIT_2. |
2ff61f9d BJ |
676 | */ |
677 | case TCPS_FIN_WAIT_1: | |
fdae4427 BJ |
678 | if (ourfinisacked) { |
679 | /* | |
680 | * If we can't receive any more | |
681 | * data, then closing user can proceed. | |
a17510f3 MK |
682 | * Starting the timer is contrary to the |
683 | * specification, but if we don't get a FIN | |
684 | * we'll hang forever. | |
fdae4427 | 685 | */ |
a17510f3 | 686 | if (so->so_state & SS_CANTRCVMORE) { |
fdae4427 | 687 | soisdisconnected(so); |
a17510f3 MK |
688 | tp->t_timer[TCPT_2MSL] = TCPTV_MAXIDLE; |
689 | } | |
8a13b737 | 690 | tp->t_state = TCPS_FIN_WAIT_2; |
fdae4427 | 691 | } |
87e78f19 BJ |
692 | break; |
693 | ||
2ff61f9d BJ |
694 | /* |
695 | * In CLOSING STATE in addition to the processing for | |
696 | * the ESTABLISHED state if the ACK acknowledges our FIN | |
697 | * then enter the TIME-WAIT state, otherwise ignore | |
698 | * the segment. | |
699 | */ | |
700 | case TCPS_CLOSING: | |
4aed14e3 | 701 | if (ourfinisacked) { |
2ff61f9d | 702 | tp->t_state = TCPS_TIME_WAIT; |
4aed14e3 BJ |
703 | tcp_canceltimers(tp); |
704 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; | |
705 | soisdisconnected(so); | |
706 | } | |
707 | break; | |
87e78f19 | 708 | |
2ff61f9d | 709 | /* |
8a13b737 BJ |
710 | * The only thing that can arrive in LAST_ACK state |
711 | * is an acknowledgment of our FIN. If our FIN is now | |
712 | * acknowledged, delete the TCB, enter the closed state | |
713 | * and return. | |
2ff61f9d BJ |
714 | */ |
715 | case TCPS_LAST_ACK: | |
0e3936fa SL |
716 | if (ourfinisacked) |
717 | tp = tcp_close(tp); | |
2ff61f9d | 718 | goto drop; |
87e78f19 | 719 | |
2ff61f9d BJ |
720 | /* |
721 | * In TIME_WAIT state the only thing that should arrive | |
722 | * is a retransmission of the remote FIN. Acknowledge | |
723 | * it and restart the finack timer. | |
724 | */ | |
725 | case TCPS_TIME_WAIT: | |
405c9168 | 726 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 727 | goto dropafterack; |
87e78f19 | 728 | } |
8a13b737 BJ |
729 | #undef ourfinisacked |
730 | } | |
87e78f19 | 731 | |
2ff61f9d | 732 | step6: |
4aed14e3 BJ |
733 | /* |
734 | * Update window information. | |
bbaaf0fd | 735 | * Don't look at window if no ACK: TAC's send garbage on first SYN. |
4aed14e3 | 736 | */ |
bbaaf0fd MK |
737 | if ((tiflags & TH_ACK) && |
738 | (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && | |
8e65fd66 | 739 | (SEQ_LT(tp->snd_wl2, ti->ti_ack) || |
bbaaf0fd | 740 | tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd))) { |
4aed14e3 BJ |
741 | tp->snd_wnd = ti->ti_win; |
742 | tp->snd_wl1 = ti->ti_seq; | |
743 | tp->snd_wl2 = ti->ti_ack; | |
18a438b6 MK |
744 | if (tp->snd_wnd > tp->max_sndwnd) |
745 | tp->max_sndwnd = tp->snd_wnd; | |
91039e49 MK |
746 | needoutput = 1; |
747 | } | |
4aed14e3 | 748 | |
2ff61f9d | 749 | /* |
b2db9217 | 750 | * Process segments with URG. |
2ff61f9d | 751 | */ |
9c811062 BJ |
752 | if ((tiflags & TH_URG) && ti->ti_urp && |
753 | TCPS_HAVERCVDFIN(tp->t_state) == 0) { | |
f4be5024 | 754 | /* |
bbaaf0fd | 755 | * This is a kludge, but if we receive and accept |
a5d9c993 SL |
756 | * random urgent pointers, we'll crash in |
757 | * soreceive. It's hard to imagine someone | |
758 | * actually wanting to send this much urgent data. | |
f4be5024 | 759 | */ |
2f4f574f | 760 | if (ti->ti_urp + so->so_rcv.sb_cc > SB_MAX) { |
f4be5024 SL |
761 | ti->ti_urp = 0; /* XXX */ |
762 | tiflags &= ~TH_URG; /* XXX */ | |
bbaaf0fd | 763 | goto dodata; /* XXX */ |
f4be5024 | 764 | } |
b2db9217 BJ |
765 | /* |
766 | * If this segment advances the known urgent pointer, | |
767 | * then mark the data stream. This should not happen | |
768 | * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since | |
769 | * a FIN has been received from the remote side. | |
770 | * In these states we ignore the URG. | |
ae6760c5 MK |
771 | * |
772 | * According to RFC961 (Assigned Protocols), | |
773 | * the urgent pointer points to the last octet | |
774 | * of urgent data. We continue, however, | |
775 | * to consider it to indicate the first octet | |
776 | * of data past the urgent section | |
777 | * as the original spec states. | |
b2db9217 BJ |
778 | */ |
779 | if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { | |
780 | tp->rcv_up = ti->ti_seq + ti->ti_urp; | |
781 | so->so_oobmark = so->so_rcv.sb_cc + | |
782 | (tp->rcv_up - tp->rcv_nxt) - 1; | |
783 | if (so->so_oobmark == 0) | |
784 | so->so_state |= SS_RCVATMARK; | |
77a4e3ca | 785 | sohasoutofband(so); |
a17510f3 | 786 | tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); |
b2db9217 BJ |
787 | } |
788 | /* | |
789 | * Remove out of band data so doesn't get presented to user. | |
790 | * This can happen independent of advancing the URG pointer, | |
791 | * but if two URG's are pending at once, some out-of-band | |
792 | * data may creep in... ick. | |
793 | */ | |
ae6760c5 MK |
794 | if (ti->ti_urp <= ti->ti_len && |
795 | (so->so_options & SO_OOBINLINE) == 0) | |
b2db9217 | 796 | tcp_pulloutofband(so, ti); |
bbaaf0fd MK |
797 | } else |
798 | /* | |
799 | * If no out of band data is expected, | |
800 | * pull receive urgent pointer along | |
801 | * with the receive window. | |
802 | */ | |
803 | if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) | |
804 | tp->rcv_up = tp->rcv_nxt; | |
805 | dodata: /* XXX */ | |
87e78f19 BJ |
806 | |
807 | /* | |
2ff61f9d BJ |
808 | * Process the segment text, merging it into the TCP sequencing queue, |
809 | * and arranging for acknowledgment of receipt if necessary. | |
810 | * This process logically involves adjusting tp->rcv_wnd as data | |
811 | * is presented to the user (this happens in tcp_usrreq.c, | |
812 | * case PRU_RCVD). If a FIN has already been received on this | |
813 | * connection then we just ignore the text. | |
87e78f19 | 814 | */ |
7984a662 MK |
815 | if ((ti->ti_len || (tiflags&TH_FIN)) && |
816 | TCPS_HAVERCVDFIN(tp->t_state) == 0) { | |
a17510f3 | 817 | TCP_REASS(tp, ti, m, so, tiflags); |
8b5a83bb BJ |
818 | if (tcpnodelack == 0) |
819 | tp->t_flags |= TF_DELACK; | |
820 | else | |
821 | tp->t_flags |= TF_ACKNOW; | |
18a438b6 MK |
822 | /* |
823 | * Note the amount of data that peer has sent into | |
824 | * our window, in order to estimate the sender's | |
825 | * buffer size. | |
826 | */ | |
827 | len = so->so_rcv.sb_hiwat - (tp->rcv_nxt - tp->rcv_adv); | |
828 | if (len > tp->max_rcvd) | |
829 | tp->max_rcvd = len; | |
4aed14e3 | 830 | } else { |
2b4b57cd | 831 | m_freem(m); |
e832edbc | 832 | tiflags &= ~TH_FIN; |
4aed14e3 | 833 | } |
87e78f19 BJ |
834 | |
835 | /* | |
e832edbc BJ |
836 | * If FIN is received ACK the FIN and let the user know |
837 | * that the connection is closing. | |
87e78f19 | 838 | */ |
e832edbc | 839 | if (tiflags & TH_FIN) { |
4aed14e3 BJ |
840 | if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { |
841 | socantrcvmore(so); | |
842 | tp->t_flags |= TF_ACKNOW; | |
843 | tp->rcv_nxt++; | |
844 | } | |
2ff61f9d | 845 | switch (tp->t_state) { |
87e78f19 | 846 | |
2ff61f9d BJ |
847 | /* |
848 | * In SYN_RECEIVED and ESTABLISHED STATES | |
849 | * enter the CLOSE_WAIT state. | |
53a5409e | 850 | */ |
2ff61f9d BJ |
851 | case TCPS_SYN_RECEIVED: |
852 | case TCPS_ESTABLISHED: | |
853 | tp->t_state = TCPS_CLOSE_WAIT; | |
854 | break; | |
53a5409e | 855 | |
2ff61f9d | 856 | /* |
8a13b737 BJ |
857 | * If still in FIN_WAIT_1 STATE FIN has not been acked so |
858 | * enter the CLOSING state. | |
53a5409e | 859 | */ |
2ff61f9d | 860 | case TCPS_FIN_WAIT_1: |
8a13b737 | 861 | tp->t_state = TCPS_CLOSING; |
2ff61f9d | 862 | break; |
87e78f19 | 863 | |
2ff61f9d BJ |
864 | /* |
865 | * In FIN_WAIT_2 state enter the TIME_WAIT state, | |
866 | * starting the time-wait timer, turning off the other | |
867 | * standard timers. | |
868 | */ | |
869 | case TCPS_FIN_WAIT_2: | |
4aed14e3 | 870 | tp->t_state = TCPS_TIME_WAIT; |
a6503abf | 871 | tcp_canceltimers(tp); |
405c9168 | 872 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
4aed14e3 | 873 | soisdisconnected(so); |
2ff61f9d BJ |
874 | break; |
875 | ||
53a5409e | 876 | /* |
2ff61f9d | 877 | * In TIME_WAIT state restart the 2 MSL time_wait timer. |
53a5409e | 878 | */ |
2ff61f9d | 879 | case TCPS_TIME_WAIT: |
405c9168 | 880 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 881 | break; |
8a13b737 | 882 | } |
87e78f19 | 883 | } |
4b935108 BJ |
884 | if (so->so_options & SO_DEBUG) |
885 | tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); | |
8a13b737 BJ |
886 | |
887 | /* | |
888 | * Return any desired output. | |
889 | */ | |
91039e49 | 890 | if (needoutput || (tp->t_flags & TF_ACKNOW)) |
bbaaf0fd | 891 | (void) tcp_output(tp); |
2ff61f9d | 892 | return; |
8a13b737 | 893 | |
2ff61f9d | 894 | dropafterack: |
8a13b737 | 895 | /* |
1e977657 BJ |
896 | * Generate an ACK dropping incoming segment if it occupies |
897 | * sequence space, where the ACK reflects our state. | |
8a13b737 | 898 | */ |
ad616704 | 899 | if (tiflags & TH_RST) |
8a13b737 | 900 | goto drop; |
f3cdd721 BJ |
901 | if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG) |
902 | tcp_trace(TA_RESPOND, ostate, tp, &tcp_saveti, 0); | |
8e65fd66 | 903 | tcp_respond(tp, ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK); |
4b6b94ca | 904 | return; |
8a13b737 BJ |
905 | |
906 | dropwithreset: | |
f37c1c84 | 907 | if (om) { |
668cc26d | 908 | (void) m_free(om); |
f37c1c84 SL |
909 | om = 0; |
910 | } | |
8a13b737 | 911 | /* |
4aed14e3 | 912 | * Generate a RST, dropping incoming segment. |
8a13b737 | 913 | * Make ACK acceptable to originator of segment. |
224f3a72 | 914 | * Don't bother to respond if destination was broadcast. |
8a13b737 | 915 | */ |
224f3a72 | 916 | if ((tiflags & TH_RST) || in_broadcast(ti->ti_dst)) |
8a13b737 BJ |
917 | goto drop; |
918 | if (tiflags & TH_ACK) | |
8e65fd66 | 919 | tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); |
8a13b737 BJ |
920 | else { |
921 | if (tiflags & TH_SYN) | |
922 | ti->ti_len++; | |
1e977657 BJ |
923 | tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, |
924 | TH_RST|TH_ACK); | |
8a13b737 | 925 | } |
7aa16f99 SL |
926 | /* destroy temporarily created socket */ |
927 | if (dropsocket) | |
928 | (void) soabort(so); | |
4b6b94ca | 929 | return; |
8a13b737 | 930 | |
2ff61f9d | 931 | drop: |
01b1394e SL |
932 | if (om) |
933 | (void) m_free(om); | |
8a13b737 BJ |
934 | /* |
935 | * Drop space held by incoming segment and return. | |
936 | */ | |
f3cdd721 BJ |
937 | if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) |
938 | tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); | |
2ff61f9d | 939 | m_freem(m); |
7aa16f99 SL |
940 | /* destroy temporarily created socket */ |
941 | if (dropsocket) | |
942 | (void) soabort(so); | |
4b935108 | 943 | return; |
2ff61f9d BJ |
944 | } |
945 | ||
99578149 | 946 | tcp_dooptions(tp, om, ti) |
8b5a83bb BJ |
947 | struct tcpcb *tp; |
948 | struct mbuf *om; | |
99578149 | 949 | struct tcpiphdr *ti; |
5e74df82 | 950 | { |
8b5a83bb BJ |
951 | register u_char *cp; |
952 | int opt, optlen, cnt; | |
953 | ||
954 | cp = mtod(om, u_char *); | |
955 | cnt = om->m_len; | |
956 | for (; cnt > 0; cnt -= optlen, cp += optlen) { | |
957 | opt = cp[0]; | |
958 | if (opt == TCPOPT_EOL) | |
959 | break; | |
960 | if (opt == TCPOPT_NOP) | |
961 | optlen = 1; | |
357b20fc | 962 | else { |
8b5a83bb | 963 | optlen = cp[1]; |
357b20fc SL |
964 | if (optlen <= 0) |
965 | break; | |
966 | } | |
8b5a83bb BJ |
967 | switch (opt) { |
968 | ||
969 | default: | |
970 | break; | |
971 | ||
972 | case TCPOPT_MAXSEG: | |
973 | if (optlen != 4) | |
974 | continue; | |
99578149 MK |
975 | if (!(ti->ti_flags & TH_SYN)) |
976 | continue; | |
8b5a83bb | 977 | tp->t_maxseg = *(u_short *)(cp + 2); |
668cc26d | 978 | tp->t_maxseg = ntohs((u_short)tp->t_maxseg); |
99578149 | 979 | tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp)); |
8b5a83bb | 980 | break; |
8b5a83bb | 981 | } |
5e74df82 | 982 | } |
668cc26d | 983 | (void) m_free(om); |
5e74df82 BJ |
984 | } |
985 | ||
b2db9217 BJ |
986 | /* |
987 | * Pull out of band byte out of a segment so | |
988 | * it doesn't appear in the user's data queue. | |
989 | * It is still reflected in the segment length for | |
990 | * sequencing purposes. | |
991 | */ | |
992 | tcp_pulloutofband(so, ti) | |
993 | struct socket *so; | |
994 | struct tcpiphdr *ti; | |
995 | { | |
996 | register struct mbuf *m; | |
1acff8ec | 997 | int cnt = ti->ti_urp - 1; |
b2db9217 BJ |
998 | |
999 | m = dtom(ti); | |
1000 | while (cnt >= 0) { | |
1001 | if (m->m_len > cnt) { | |
1002 | char *cp = mtod(m, caddr_t) + cnt; | |
1003 | struct tcpcb *tp = sototcpcb(so); | |
1004 | ||
1005 | tp->t_iobc = *cp; | |
1006 | tp->t_oobflags |= TCPOOB_HAVEDATA; | |
668cc26d | 1007 | bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); |
b2db9217 BJ |
1008 | m->m_len--; |
1009 | return; | |
1010 | } | |
1011 | cnt -= m->m_len; | |
1012 | m = m->m_next; | |
1013 | if (m == 0) | |
1014 | break; | |
1015 | } | |
1016 | panic("tcp_pulloutofband"); | |
1017 | } | |
1018 | ||
99578149 MK |
1019 | /* |
1020 | * Determine a reasonable value for maxseg size. | |
1021 | * If the route is known, use one that can be handled | |
1022 | * on the given interface without forcing IP to fragment. | |
c2a1cd2c | 1023 | * If bigger than a page (CLBYTES), round down to nearest pagesize |
99578149 MK |
1024 | * to utilize pagesize mbufs. |
1025 | * If interface pointer is unavailable, or the destination isn't local, | |
c2a1cd2c MK |
1026 | * use a conservative size (512 or the default IP max size, but no more |
1027 | * than the mtu of the interface through which we route), | |
99578149 MK |
1028 | * as we can't discover anything about intervening gateways or networks. |
1029 | * | |
1030 | * This is ugly, and doesn't belong at this level, but has to happen somehow. | |
1031 | */ | |
1032 | tcp_mss(tp) | |
c2a1cd2c | 1033 | register struct tcpcb *tp; |
99578149 MK |
1034 | { |
1035 | struct route *ro; | |
1036 | struct ifnet *ifp; | |
1037 | int mss; | |
1038 | struct inpcb *inp; | |
1039 | ||
1040 | inp = tp->t_inpcb; | |
1041 | ro = &inp->inp_route; | |
1042 | if ((ro->ro_rt == (struct rtentry *)0) || | |
1043 | (ifp = ro->ro_rt->rt_ifp) == (struct ifnet *)0) { | |
1044 | /* No route yet, so try to acquire one */ | |
1045 | if (inp->inp_faddr.s_addr != INADDR_ANY) { | |
1046 | ro->ro_dst.sa_family = AF_INET; | |
1047 | ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = | |
1048 | inp->inp_faddr; | |
1049 | rtalloc(ro); | |
1050 | } | |
1051 | if ((ro->ro_rt == 0) || (ifp = ro->ro_rt->rt_ifp) == 0) | |
0d115dcc | 1052 | return (TCP_MSS); |
99578149 MK |
1053 | } |
1054 | ||
1055 | mss = ifp->if_mtu - sizeof(struct tcpiphdr); | |
1056 | #if (CLBYTES & (CLBYTES - 1)) == 0 | |
1057 | if (mss > CLBYTES) | |
1058 | mss &= ~(CLBYTES-1); | |
1059 | #else | |
1060 | if (mss > CLBYTES) | |
1061 | mss = mss / CLBYTES * CLBYTES; | |
1062 | #endif | |
c2a1cd2c MK |
1063 | if (in_localaddr(inp->inp_faddr)) |
1064 | return (mss); | |
0d115dcc | 1065 | return (MIN(mss, TCP_MSS)); |
99578149 | 1066 | } |