Commit | Line | Data |
---|---|---|
ac83b17a | 1 | /* tcp_input.c 1.37 81/12/09 */ |
87e78f19 BJ |
2 | |
3 | #include "../h/param.h" | |
4 | #include "../h/systm.h" | |
dad64fdf | 5 | #include "../h/mbuf.h" |
8a13b737 | 6 | #include "../h/protosw.h" |
dad64fdf | 7 | #include "../h/socket.h" |
d52566dd | 8 | #include "../h/socketvar.h" |
8a13b737 BJ |
9 | #include "../net/in.h" |
10 | #include "../net/in_pcb.h" | |
11 | #include "../net/in_systm.h" | |
12 | #include "../net/if.h" | |
d52566dd | 13 | #include "../net/ip.h" |
eb44bfb2 | 14 | #include "../net/ip_var.h" |
d52566dd BJ |
15 | #include "../net/tcp.h" |
16 | #include "../net/tcp_fsm.h" | |
8a13b737 BJ |
17 | #include "../net/tcp_seq.h" |
18 | #include "../net/tcp_timer.h" | |
d52566dd | 19 | #include "../net/tcp_var.h" |
8a13b737 | 20 | #include "../net/tcpip.h" |
f1b2fa5b | 21 | #include "../errno.h" |
87e78f19 | 22 | |
60b16fa9 | 23 | int tcpcksum = 1; |
87e78f19 | 24 | |
2ff61f9d BJ |
25 | /* |
26 | * TCP input routine, follows pages 65-76 of the | |
27 | * protocol specification dated September, 1981 very closely. | |
28 | */ | |
2b4b57cd BJ |
29 | tcp_input(m0) |
30 | struct mbuf *m0; | |
87e78f19 | 31 | { |
2b4b57cd | 32 | register struct tcpiphdr *ti; |
53a5409e | 33 | struct inpcb *inp; |
2b4b57cd BJ |
34 | register struct mbuf *m; |
35 | int len, tlen, off; | |
2b4b57cd | 36 | register struct tcpcb *tp; |
2b4b57cd | 37 | register int tiflags; |
d52566dd | 38 | struct socket *so; |
f1b2fa5b | 39 | int todrop, acked; |
87e78f19 | 40 | |
2b4b57cd | 41 | COUNT(TCP_INPUT); |
87e78f19 | 42 | /* |
2b4b57cd | 43 | * Get ip and tcp header together in first mbuf. |
ac83b17a | 44 | * Note: ip leaves ip header in first mbuf. |
87e78f19 | 45 | */ |
2b4b57cd | 46 | m = m0; |
20790db4 | 47 | ti = mtod(m, struct tcpiphdr *); |
ac83b17a | 48 | if (((struct ip *)ti)->ip_len > sizeof (struct ip)) |
d63599ac | 49 | ip_stripoptions((struct ip *)ti, (struct mbuf *)0); |
8a13b737 BJ |
50 | if (m->m_len < sizeof (struct tcpiphdr)) { |
51 | if (m_pullup(m, sizeof (struct tcpiphdr)) == 0) { | |
52 | tcpstat.tcps_hdrops++; | |
53 | goto drop; | |
54 | } | |
55 | ti = mtod(m, struct tcpiphdr *); | |
56 | } | |
87e78f19 | 57 | |
2b4b57cd BJ |
58 | /* |
59 | * Checksum extended tcp header and data. | |
60 | */ | |
61 | tlen = ((struct ip *)ti)->ip_len; | |
62 | len = sizeof (struct ip) + tlen; | |
60b16fa9 | 63 | if (tcpcksum) { |
2b4b57cd BJ |
64 | ti->ti_next = ti->ti_prev = 0; |
65 | ti->ti_x1 = 0; | |
ac83b17a BJ |
66 | ti->ti_len = (u_short)tlen; |
67 | #if vax | |
68 | ti->ti_len = htons(ti->ti_len); | |
69 | #endif | |
8a13b737 | 70 | if ((ti->ti_sum = in_cksum(m, len)) != 0xffff) { |
2b4b57cd | 71 | tcpstat.tcps_badsum++; |
2ff61f9d | 72 | printf("tcp cksum %x\n", ti->ti_sum); |
8a13b737 | 73 | goto drop; |
87e78f19 BJ |
74 | } |
75 | } | |
76 | ||
77 | /* | |
2b4b57cd BJ |
78 | * Check that tcp offset makes sense, |
79 | * process tcp options and adjust length. | |
87e78f19 | 80 | */ |
2b4b57cd BJ |
81 | off = ti->ti_off << 2; |
82 | if (off < sizeof (struct tcphdr) || off > ti->ti_len) { | |
83 | tcpstat.tcps_badoff++; | |
8a13b737 | 84 | goto drop; |
2b4b57cd BJ |
85 | } |
86 | ti->ti_len = tlen - off; | |
8a13b737 BJ |
87 | #if 0 |
88 | if (off > sizeof (struct tcphdr) >> 2) | |
89 | tcp_options(ti); | |
90 | #endif | |
2ff61f9d | 91 | tiflags = ti->ti_flags; |
2b4b57cd | 92 | |
8a13b737 BJ |
93 | /* |
94 | * Convert tcp protocol specific fields to host format. | |
95 | */ | |
96 | ti->ti_seq = ntohl(ti->ti_seq); | |
97 | ti->ti_ack = ntohl(ti->ti_ack); | |
98 | ti->ti_win = ntohs(ti->ti_win); | |
99 | ti->ti_urp = ntohs(ti->ti_urp); | |
100 | ||
2b4b57cd | 101 | /* |
2b4b57cd BJ |
102 | * Locate pcb for segment. |
103 | */ | |
2ff61f9d BJ |
104 | inp = in_pcblookup |
105 | (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport); | |
106 | ||
107 | /* | |
108 | * If the state is CLOSED (i.e., TCB does not exist) then | |
109 | * all data in the incoming segment is discarded. (p. 65). | |
110 | */ | |
53a5409e | 111 | if (inp == 0) |
8a13b737 | 112 | goto dropwithreset; |
2ff61f9d BJ |
113 | tp = intotcpcb(inp); |
114 | if (tp == 0) | |
8a13b737 | 115 | goto dropwithreset; |
f1b2fa5b | 116 | so = inp->inp_socket; |
87e78f19 | 117 | |
405c9168 BJ |
118 | /* |
119 | * Segment received on connection. | |
120 | * Reset idle time and keep-alive timer. | |
121 | */ | |
122 | tp->t_idle = 0; | |
123 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; | |
124 | ||
87e78f19 | 125 | /* |
8a13b737 BJ |
126 | * Calculate amount of space in receive window, |
127 | * and then do TCP input processing. | |
87e78f19 | 128 | */ |
8a13b737 | 129 | tp->rcv_wnd = sbspace(&so->so_rcv); |
2ff61f9d | 130 | |
87e78f19 BJ |
131 | switch (tp->t_state) { |
132 | ||
2ff61f9d BJ |
133 | /* |
134 | * If the state is LISTEN then ignore segment if it contains an RST. | |
135 | * If the segment contains an ACK then it is bad and send a RST. | |
136 | * If it does not contain a SYN then it is not interesting; drop it. | |
8a13b737 | 137 | * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial |
2ff61f9d | 138 | * tp->iss, and send a segment: |
8a13b737 | 139 | * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> |
2ff61f9d BJ |
140 | * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. |
141 | * Fill in remote peer address fields if not previously specified. | |
142 | * Enter SYN_RECEIVED state, and process any other fields of this | |
143 | * segment in this state. (p. 65) | |
144 | */ | |
145 | case TCPS_LISTEN: | |
146 | if (tiflags & TH_RST) | |
147 | goto drop; | |
148 | if (tiflags & TH_ACK) | |
8a13b737 | 149 | goto dropwithreset; |
2ff61f9d BJ |
150 | if ((tiflags & TH_SYN) == 0) |
151 | goto drop; | |
8a13b737 | 152 | tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; |
2ff61f9d | 153 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
154 | tcp_sendseqinit(tp); |
155 | tcp_rcvseqinit(tp); | |
2ff61f9d | 156 | tp->t_state = TCPS_SYN_RECEIVED; |
2ff61f9d BJ |
157 | if (inp->inp_faddr.s_addr == 0) { |
158 | inp->inp_faddr = ti->ti_src; | |
159 | inp->inp_fport = ti->ti_sport; | |
87e78f19 | 160 | } |
8a13b737 | 161 | goto trimthenstep6; |
87e78f19 | 162 | |
2ff61f9d BJ |
163 | /* |
164 | * If the state is SYN_SENT: | |
165 | * if seg contains an ACK, but not for our SYN, drop the input. | |
166 | * if seg contains a RST, then drop the connection. | |
167 | * if seg does not contain SYN, then drop it. | |
168 | * Otherwise this is an acceptable SYN segment | |
169 | * initialize tp->rcv_nxt and tp->irs | |
170 | * if seg contains ack then advance tp->snd_una | |
171 | * if SYN has been acked change to ESTABLISHED else SYN_RCVD state | |
172 | * arrange for segment to be acked (eventually) | |
173 | * continue processing rest of data/controls, beginning with URG | |
174 | */ | |
175 | case TCPS_SYN_SENT: | |
176 | if ((tiflags & TH_ACK) && | |
177 | (SEQ_LEQ(ti->ti_ack, tp->iss) || | |
8a13b737 BJ |
178 | SEQ_GT(ti->ti_ack, tp->snd_nxt))) |
179 | goto dropwithreset; | |
2ff61f9d BJ |
180 | if (tiflags & TH_RST) { |
181 | if (tiflags & TH_ACK) | |
8a13b737 | 182 | tcp_drop(tp, ECONNRESET); |
2ff61f9d | 183 | goto drop; |
87e78f19 | 184 | } |
2ff61f9d BJ |
185 | if ((tiflags & TH_SYN) == 0) |
186 | goto drop; | |
8a13b737 BJ |
187 | tp->iss = ti->ti_ack; |
188 | tcp_sendseqinit(tp); | |
2ff61f9d | 189 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
190 | tcp_rcvseqinit(tp); |
191 | tp->t_flags |= TF_ACKNOW; | |
405c9168 | 192 | if (SEQ_GT(tp->snd_una, tp->iss)) { |
2ff61f9d | 193 | tp->t_state = TCPS_ESTABLISHED; |
405c9168 BJ |
194 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
195 | } else | |
8a13b737 BJ |
196 | tp->t_state = TCPS_SYN_RECEIVED; |
197 | goto trimthenstep6; | |
198 | ||
199 | trimthenstep6: | |
200 | /* | |
201 | * If had syn, advance ti->ti_seq to correspond | |
202 | * to first data byte. | |
203 | */ | |
204 | if (tiflags & TH_SYN) | |
205 | ti->ti_seq++; | |
206 | ||
207 | /* | |
208 | * If data, trim to stay within window, | |
209 | * dropping FIN if necessary. | |
210 | */ | |
211 | if (ti->ti_len > tp->rcv_wnd) { | |
212 | todrop = ti->ti_len - tp->rcv_wnd; | |
213 | m_adj(m, -todrop); | |
214 | ti->ti_len = tp->rcv_wnd; | |
215 | ti->ti_flags &= ~TH_FIN; | |
87e78f19 | 216 | } |
8a13b737 | 217 | goto step6; |
2ff61f9d | 218 | } |
87e78f19 | 219 | |
2ff61f9d BJ |
220 | /* |
221 | * States other than LISTEN or SYN_SENT. | |
222 | * First check that at least some bytes of segment are within | |
223 | * receive window. | |
224 | */ | |
225 | if (tp->rcv_wnd == 0) { | |
226 | /* | |
227 | * If window is closed can only take segments at | |
228 | * window edge, and have to drop data and EOL from | |
229 | * incoming segments. | |
230 | */ | |
231 | if (tp->rcv_nxt != ti->ti_seq) | |
232 | goto dropafterack; | |
8a13b737 BJ |
233 | if (ti->ti_len > 0) { |
234 | ti->ti_len = 0; | |
235 | ti->ti_flags &= ~(TH_PUSH|TH_FIN); | |
87e78f19 | 236 | } |
2ff61f9d BJ |
237 | } else { |
238 | /* | |
239 | * If segment begins before rcv_next, drop leading | |
240 | * data (and SYN); if nothing left, just ack. | |
241 | */ | |
242 | if (SEQ_GT(tp->rcv_nxt, ti->ti_seq)) { | |
8a13b737 BJ |
243 | todrop = tp->rcv_nxt - ti->ti_seq; |
244 | if (tiflags & TH_SYN) { | |
245 | ti->ti_seq++; | |
246 | if (ti->ti_urp > 1) | |
247 | ti->ti_urp--; | |
248 | else | |
249 | tiflags &= ~TH_URG; | |
250 | todrop--; | |
251 | } | |
2ff61f9d BJ |
252 | if (todrop > ti->ti_len) |
253 | goto dropafterack; | |
254 | m_adj(m, todrop); | |
255 | ti->ti_seq += todrop; | |
256 | ti->ti_len -= todrop; | |
8a13b737 BJ |
257 | if (ti->ti_urp > todrop) |
258 | ti->ti_urp -= todrop; | |
259 | else { | |
260 | tiflags &= ~TH_URG; | |
261 | /* ti->ti_flags &= ~TH_URG; */ | |
262 | /* ti->ti_urp = 0; */ | |
263 | } | |
264 | /* tiflags &= ~TH_SYN; */ | |
265 | /* ti->ti_flags &= ~TH_SYN; */ | |
2ff61f9d BJ |
266 | } |
267 | /* | |
268 | * If segment ends after window, drop trailing data | |
8a13b737 | 269 | * (and PUSH and FIN); if nothing left, just ACK. |
2ff61f9d BJ |
270 | */ |
271 | if (SEQ_GT(ti->ti_seq+ti->ti_len, tp->rcv_nxt+tp->rcv_wnd)) { | |
8a13b737 | 272 | todrop = |
2ff61f9d BJ |
273 | ti->ti_seq+ti->ti_len - (tp->rcv_nxt+tp->rcv_wnd); |
274 | if (todrop > ti->ti_len) | |
275 | goto dropafterack; | |
276 | m_adj(m, -todrop); | |
277 | ti->ti_len -= todrop; | |
8a13b737 | 278 | ti->ti_flags &= ~(TH_PUSH|TH_FIN); |
87e78f19 | 279 | } |
87e78f19 | 280 | } |
87e78f19 | 281 | |
87e78f19 | 282 | /* |
2ff61f9d BJ |
283 | * If the RST bit is set examine the state: |
284 | * SYN_RECEIVED STATE: | |
285 | * If passive open, return to LISTEN state. | |
286 | * If active open, inform user that connection was refused. | |
287 | * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: | |
288 | * Inform user that connection was reset, and close tcb. | |
289 | * CLOSING, LAST_ACK, TIME_WAIT STATES | |
290 | * Close the tcb. | |
87e78f19 | 291 | */ |
2ff61f9d BJ |
292 | if (tiflags&TH_RST) switch (tp->t_state) { |
293 | ||
294 | case TCPS_SYN_RECEIVED: | |
295 | if (inp->inp_socket->so_options & SO_ACCEPTCONN) { | |
8a13b737 BJ |
296 | tp->t_state = TCPS_LISTEN; |
297 | inp->inp_faddr.s_addr = 0; | |
2ff61f9d BJ |
298 | goto drop; |
299 | } | |
8a13b737 | 300 | tcp_drop(tp, ECONNREFUSED); |
2ff61f9d BJ |
301 | goto drop; |
302 | ||
303 | case TCPS_ESTABLISHED: | |
304 | case TCPS_FIN_WAIT_1: | |
305 | case TCPS_FIN_WAIT_2: | |
306 | case TCPS_CLOSE_WAIT: | |
307 | tcp_drop(tp, ECONNRESET); | |
308 | goto drop; | |
309 | ||
310 | case TCPS_CLOSING: | |
311 | case TCPS_LAST_ACK: | |
312 | case TCPS_TIME_WAIT: | |
313 | tcp_close(tp); | |
314 | goto drop; | |
87e78f19 | 315 | } |
87e78f19 BJ |
316 | |
317 | /* | |
2ff61f9d BJ |
318 | * If a SYN is in the window, then this is an |
319 | * error and we send an RST and drop the connection. | |
320 | */ | |
321 | if (tiflags & TH_SYN) { | |
8a13b737 BJ |
322 | tcp_drop(tp, ECONNABORTED); |
323 | goto dropwithreset; | |
2ff61f9d BJ |
324 | } |
325 | ||
326 | /* | |
327 | * If the ACK bit is off we drop the segment and return. | |
328 | */ | |
8a13b737 | 329 | if ((tiflags & TH_ACK) == 0) |
2ff61f9d BJ |
330 | goto drop; |
331 | ||
332 | /* | |
333 | * Ack processing. | |
87e78f19 | 334 | */ |
87e78f19 BJ |
335 | switch (tp->t_state) { |
336 | ||
2ff61f9d BJ |
337 | /* |
338 | * In SYN_RECEIVED state if the ack ACKs our SYN then enter | |
339 | * ESTABLISHED state and continue processing, othewise | |
340 | * send an RST. | |
341 | */ | |
342 | case TCPS_SYN_RECEIVED: | |
8a13b737 BJ |
343 | if (SEQ_GT(tp->snd_una, ti->ti_ack) || |
344 | SEQ_GT(ti->ti_ack, tp->snd_nxt)) | |
345 | goto dropwithreset; | |
346 | soisconnected(so); | |
347 | tp->t_state = TCPS_ESTABLISHED; | |
405c9168 | 348 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
8a13b737 | 349 | /* fall into ... */ |
87e78f19 | 350 | |
2ff61f9d BJ |
351 | /* |
352 | * In ESTABLISHED state: drop duplicate ACKs; ACK out of range | |
353 | * ACKs. If the ack is in the range | |
354 | * tp->snd_una < ti->ti_ack <= tp->snd_nxt | |
355 | * then advance tp->snd_una to ti->ti_ack and drop | |
356 | * data from the retransmission queue. If this ACK reflects | |
357 | * more up to date window information we update our window information. | |
358 | */ | |
359 | case TCPS_ESTABLISHED: | |
360 | case TCPS_FIN_WAIT_1: | |
361 | case TCPS_FIN_WAIT_2: | |
362 | case TCPS_CLOSE_WAIT: | |
363 | case TCPS_CLOSING: | |
8a13b737 BJ |
364 | #define ourfinisacked (acked > 0) |
365 | ||
2ff61f9d BJ |
366 | if (SEQ_LT(ti->ti_ack, tp->snd_una)) |
367 | break; | |
368 | if (SEQ_GT(ti->ti_ack, tp->snd_nxt)) | |
369 | goto dropafterack; | |
8a13b737 BJ |
370 | acked = ti->ti_ack - tp->snd_una; |
371 | if (acked > so->so_snd.sb_cc) { | |
372 | sbflush(&so->so_snd); | |
373 | acked -= so->so_snd.sb_cc; | |
405c9168 | 374 | /* if acked our FIN is acked */ |
8a13b737 BJ |
375 | } else { |
376 | sbdrop(&so->so_snd, acked); | |
377 | acked = 0; | |
378 | } | |
405c9168 BJ |
379 | |
380 | /* | |
381 | * If transmit timer is running and timed sequence | |
382 | * number was acked, update smoothed round trip time. | |
383 | */ | |
384 | if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { | |
385 | tp->t_srtt = | |
386 | tcp_beta * tp->t_srtt + | |
387 | (1 - tcp_beta) * tp->t_rtt; | |
388 | tp->t_rtt = 0; | |
389 | } | |
390 | ||
2ff61f9d | 391 | tp->snd_una = ti->ti_ack; |
8a13b737 BJ |
392 | |
393 | /* | |
394 | * Update window information. | |
395 | */ | |
2ff61f9d | 396 | if (SEQ_LT(tp->snd_wl1, ti->ti_seq) || |
8a13b737 | 397 | tp->snd_wl1==ti->ti_seq && SEQ_LEQ(tp->snd_wl2,ti->ti_seq)) { |
2ff61f9d BJ |
398 | tp->snd_wnd = ti->ti_win; |
399 | tp->snd_wl1 = ti->ti_seq; | |
400 | tp->snd_wl2 = ti->ti_ack; | |
87e78f19 | 401 | } |
2ff61f9d | 402 | |
87e78f19 BJ |
403 | switch (tp->t_state) { |
404 | ||
2ff61f9d BJ |
405 | /* |
406 | * In FIN_WAIT_1 STATE in addition to the processing | |
407 | * for the ESTABLISHED state if our FIN is now acknowledged | |
8a13b737 | 408 | * then enter FIN_WAIT_2. |
2ff61f9d BJ |
409 | */ |
410 | case TCPS_FIN_WAIT_1: | |
8a13b737 BJ |
411 | if (ourfinisacked) |
412 | tp->t_state = TCPS_FIN_WAIT_2; | |
87e78f19 BJ |
413 | break; |
414 | ||
2ff61f9d BJ |
415 | /* |
416 | * In CLOSING STATE in addition to the processing for | |
417 | * the ESTABLISHED state if the ACK acknowledges our FIN | |
418 | * then enter the TIME-WAIT state, otherwise ignore | |
419 | * the segment. | |
420 | */ | |
421 | case TCPS_CLOSING: | |
8a13b737 | 422 | if (ourfinisacked) |
2ff61f9d | 423 | tp->t_state = TCPS_TIME_WAIT; |
8a13b737 | 424 | goto drop; |
87e78f19 | 425 | |
2ff61f9d | 426 | /* |
8a13b737 BJ |
427 | * The only thing that can arrive in LAST_ACK state |
428 | * is an acknowledgment of our FIN. If our FIN is now | |
429 | * acknowledged, delete the TCB, enter the closed state | |
430 | * and return. | |
2ff61f9d BJ |
431 | */ |
432 | case TCPS_LAST_ACK: | |
8a13b737 | 433 | if (ourfinisacked) |
2ff61f9d BJ |
434 | tcp_close(tp); |
435 | goto drop; | |
87e78f19 | 436 | |
2ff61f9d BJ |
437 | /* |
438 | * In TIME_WAIT state the only thing that should arrive | |
439 | * is a retransmission of the remote FIN. Acknowledge | |
440 | * it and restart the finack timer. | |
441 | */ | |
442 | case TCPS_TIME_WAIT: | |
405c9168 | 443 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 444 | goto dropafterack; |
87e78f19 | 445 | } |
8a13b737 BJ |
446 | #undef ourfinisacked |
447 | } | |
87e78f19 | 448 | |
2ff61f9d BJ |
449 | step6: |
450 | /* | |
451 | * If an URG bit is set in the segment and is greater than the | |
452 | * current known urgent pointer, then signal the user that the | |
453 | * remote side has urgent data. This should not happen | |
454 | * in CLOSE_WAIT, CLOSING, LAST-ACK or TIME_WAIT STATES since | |
455 | * a FIN has been received from the remote side. In these states | |
456 | * we ignore the URG. | |
457 | */ | |
8a13b737 BJ |
458 | if ((tiflags & TH_URG) == 0 && TCPS_HAVERCVDFIN(tp->t_state) == 0) |
459 | if (SEQ_GT(ti->ti_urp, tp->rcv_up)) { | |
2ff61f9d | 460 | tp->rcv_up = ti->ti_urp; |
8a13b737 | 461 | #if 0 |
2ff61f9d | 462 | soisurgendata(so); /* XXX */ |
8a13b737 | 463 | #endif |
87e78f19 | 464 | } |
87e78f19 BJ |
465 | |
466 | /* | |
2ff61f9d BJ |
467 | * Process the segment text, merging it into the TCP sequencing queue, |
468 | * and arranging for acknowledgment of receipt if necessary. | |
469 | * This process logically involves adjusting tp->rcv_wnd as data | |
470 | * is presented to the user (this happens in tcp_usrreq.c, | |
471 | * case PRU_RCVD). If a FIN has already been received on this | |
472 | * connection then we just ignore the text. | |
87e78f19 | 473 | */ |
2ff61f9d | 474 | if (ti->ti_len) { |
8a13b737 | 475 | if (TCPS_HAVERCVDFIN(tp->t_state)) |
2ff61f9d | 476 | goto drop; |
8a13b737 BJ |
477 | off += sizeof (struct ip); /* drop IP header */ |
478 | m->m_off += off; | |
479 | m->m_len -= off; | |
2ff61f9d | 480 | tiflags = tcp_reass(tp, ti); |
8a13b737 BJ |
481 | tp->t_flags |= TF_ACKNOW; /* XXX TF_DELACK */ |
482 | } else | |
2b4b57cd | 483 | m_freem(m); |
87e78f19 BJ |
484 | |
485 | /* | |
2ff61f9d BJ |
486 | * If FIN is received then if we haven't received SYN and |
487 | * therefore can't validate drop the segment. Otherwise ACK | |
488 | * the FIN and let the user know that the connection is closing. | |
87e78f19 | 489 | */ |
8a13b737 | 490 | if ((tiflags & TH_FIN)) { |
a6503abf BJ |
491 | if (TCPS_HAVERCVDSYN(tp->t_state) == 0) |
492 | goto drop; | |
493 | socantrcvmore(so); | |
2ff61f9d BJ |
494 | tp->t_flags |= TF_ACKNOW; |
495 | tp->rcv_nxt++; | |
496 | switch (tp->t_state) { | |
87e78f19 | 497 | |
2ff61f9d BJ |
498 | /* |
499 | * In SYN_RECEIVED and ESTABLISHED STATES | |
500 | * enter the CLOSE_WAIT state. | |
53a5409e | 501 | */ |
2ff61f9d BJ |
502 | case TCPS_SYN_RECEIVED: |
503 | case TCPS_ESTABLISHED: | |
504 | tp->t_state = TCPS_CLOSE_WAIT; | |
505 | break; | |
53a5409e | 506 | |
2ff61f9d | 507 | /* |
8a13b737 BJ |
508 | * If still in FIN_WAIT_1 STATE FIN has not been acked so |
509 | * enter the CLOSING state. | |
53a5409e | 510 | */ |
2ff61f9d | 511 | case TCPS_FIN_WAIT_1: |
8a13b737 | 512 | tp->t_state = TCPS_CLOSING; |
2ff61f9d | 513 | break; |
87e78f19 | 514 | |
2ff61f9d BJ |
515 | /* |
516 | * In FIN_WAIT_2 state enter the TIME_WAIT state, | |
517 | * starting the time-wait timer, turning off the other | |
518 | * standard timers. | |
519 | */ | |
520 | case TCPS_FIN_WAIT_2: | |
8a13b737 | 521 | tp->t_state = TCPS_TIME_WAIT;; |
a6503abf | 522 | tcp_canceltimers(tp); |
405c9168 | 523 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d BJ |
524 | break; |
525 | ||
53a5409e | 526 | /* |
2ff61f9d | 527 | * In TIME_WAIT state restart the 2 MSL time_wait timer. |
53a5409e | 528 | */ |
2ff61f9d | 529 | case TCPS_TIME_WAIT: |
405c9168 | 530 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 531 | break; |
8a13b737 | 532 | } |
87e78f19 | 533 | } |
8a13b737 BJ |
534 | |
535 | /* | |
536 | * Return any desired output. | |
537 | */ | |
538 | tcp_output(tp); | |
2ff61f9d | 539 | return; |
8a13b737 | 540 | |
2ff61f9d | 541 | dropafterack: |
8a13b737 BJ |
542 | /* |
543 | * Generate an ACK, then drop incoming segment. | |
544 | * Make ACK reflect our state. | |
545 | */ | |
546 | if (tiflags & TH_RST) | |
547 | goto drop; | |
548 | tcp_respond(ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK); | |
549 | goto drop; | |
550 | ||
551 | dropwithreset: | |
552 | /* | |
553 | * Generate a RST, then drop incoming segment. | |
554 | * Make ACK acceptable to originator of segment. | |
555 | */ | |
556 | if (tiflags & TH_RST) | |
557 | goto drop; | |
558 | if (tiflags & TH_ACK) | |
f1b2fa5b | 559 | tcp_respond(ti, (tcp_seq)0, ti->ti_ack, TH_RST); |
8a13b737 BJ |
560 | else { |
561 | if (tiflags & TH_SYN) | |
562 | ti->ti_len++; | |
f1b2fa5b | 563 | tcp_respond(ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, TH_RST|TH_ACK); |
8a13b737 BJ |
564 | } |
565 | goto drop; | |
566 | ||
2ff61f9d | 567 | drop: |
8a13b737 BJ |
568 | /* |
569 | * Drop space held by incoming segment and return. | |
570 | */ | |
2ff61f9d | 571 | m_freem(m); |
2ff61f9d BJ |
572 | } |
573 | ||
574 | /* | |
575 | * Insert segment ti into reassembly queue of tcp with | |
576 | * control block tp. Return TH_FIN if reassembly now includes | |
577 | * a segment with FIN. | |
578 | */ | |
f1b2fa5b | 579 | tcp_reass(tp, ti) |
2ff61f9d BJ |
580 | register struct tcpcb *tp; |
581 | register struct tcpiphdr *ti; | |
2ff61f9d BJ |
582 | { |
583 | register struct tcpiphdr *q; | |
8a13b737 | 584 | struct socket *so = tp->t_inpcb->inp_socket; |
2ff61f9d | 585 | int flags = 0; /* no FIN */ |
8a13b737 | 586 | COUNT(TCP_REASS); |
2ff61f9d BJ |
587 | |
588 | /* | |
405c9168 BJ |
589 | * Call with ti==0 after become established to |
590 | * force pre-ESTABLISHED data up to user socket. | |
2ff61f9d | 591 | */ |
405c9168 | 592 | if (ti == 0) |
2ff61f9d | 593 | goto present; |
87e78f19 | 594 | |
2ff61f9d BJ |
595 | /* |
596 | * Find a segment which begins after this one does. | |
597 | */ | |
598 | for (q = tp->seg_next; q != (struct tcpiphdr *)tp; | |
599 | q = (struct tcpiphdr *)q->ti_next) | |
600 | if (SEQ_GT(q->ti_seq, ti->ti_seq)) | |
601 | break; | |
602 | ||
603 | /* | |
604 | * If there is a preceding segment, it may provide some of | |
605 | * our data already. If so, drop the data from the incoming | |
606 | * segment. If it provides all of our data, drop us. | |
607 | */ | |
608 | if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { | |
609 | register int i; | |
610 | q = (struct tcpiphdr *)(q->ti_prev); | |
611 | /* conversion to int (in i) handles seq wraparound */ | |
612 | i = q->ti_seq + q->ti_len - ti->ti_seq; | |
613 | if (i > 0) { | |
2b4b57cd | 614 | if (i >= ti->ti_len) |
2ff61f9d BJ |
615 | goto drop; |
616 | m_adj(dtom(tp), i); | |
2b4b57cd | 617 | ti->ti_len -= i; |
2ff61f9d | 618 | ti->ti_seq += i; |
53a5409e | 619 | } |
2ff61f9d BJ |
620 | q = (struct tcpiphdr *)(q->ti_next); |
621 | } | |
87e78f19 | 622 | |
2ff61f9d BJ |
623 | /* |
624 | * While we overlap succeeding segments trim them or, | |
625 | * if they are completely covered, dequeue them. | |
626 | */ | |
627 | while (q != (struct tcpiphdr *)tp && | |
628 | SEQ_GT(ti->ti_seq + ti->ti_len, q->ti_seq)) { | |
629 | register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; | |
630 | if (i < q->ti_len) { | |
631 | q->ti_len -= i; | |
632 | m_adj(dtom(q), i); | |
633 | break; | |
ac5e71a1 | 634 | } |
2ff61f9d BJ |
635 | q = (struct tcpiphdr *)q->ti_next; |
636 | m_freem(dtom(q->ti_prev)); | |
637 | remque(q->ti_prev); | |
638 | } | |
87e78f19 | 639 | |
2ff61f9d BJ |
640 | /* |
641 | * Stick new segment in its place. | |
642 | */ | |
643 | insque(ti, q->ti_prev); | |
2ff61f9d BJ |
644 | |
645 | /* | |
646 | * Advance rcv_next through newly completed sequence space. | |
647 | */ | |
648 | while (ti->ti_seq == tp->rcv_nxt) { | |
649 | tp->rcv_nxt += ti->ti_len; | |
650 | flags = ti->ti_flags & TH_FIN; | |
651 | ti = (struct tcpiphdr *)ti->ti_next; | |
652 | if (ti == (struct tcpiphdr *)tp) | |
653 | break; | |
60b16fa9 | 654 | } |
2ff61f9d BJ |
655 | |
656 | present: | |
657 | /* | |
658 | * Present data to user. | |
659 | */ | |
8a13b737 | 660 | if (tp->t_state < TCPS_ESTABLISHED) |
2ff61f9d | 661 | return (flags); |
2b4b57cd BJ |
662 | ti = tp->seg_next; |
663 | while (ti != (struct tcpiphdr *)tp && ti->ti_seq < tp->rcv_nxt) { | |
664 | remque(ti); | |
665 | sbappend(&so->so_rcv, dtom(ti)); | |
2b4b57cd | 666 | ti = (struct tcpiphdr *)ti->ti_next; |
2a4921ab | 667 | } |
a6503abf BJ |
668 | if (so->so_state & SS_CANTRCVMORE) |
669 | sbflush(&so->so_rcv); | |
670 | else | |
671 | sorwakeup(so); | |
2ff61f9d BJ |
672 | return (flags); |
673 | drop: | |
674 | m_freem(dtom(ti)); | |
675 | return (flags); | |
d52566dd | 676 | } |