Commit | Line | Data |
---|---|---|
2c48b3f8 | 1 | /* tcp_input.c 1.82 82/10/30 */ |
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" |
fcfe450e | 9 | #include "../netinet/in.h" |
c124e997 | 10 | #include "../net/route.h" |
fcfe450e BJ |
11 | #include "../netinet/in_pcb.h" |
12 | #include "../netinet/in_systm.h" | |
8a13b737 | 13 | #include "../net/if.h" |
fcfe450e BJ |
14 | #include "../netinet/ip.h" |
15 | #include "../netinet/ip_var.h" | |
16 | #include "../netinet/tcp.h" | |
17 | #include "../netinet/tcp_fsm.h" | |
18 | #include "../netinet/tcp_seq.h" | |
19 | #include "../netinet/tcp_timer.h" | |
20 | #include "../netinet/tcp_var.h" | |
21 | #include "../netinet/tcpip.h" | |
22 | #include "../netinet/tcp_debug.h" | |
c47a5909 | 23 | #include <errno.h> |
87e78f19 | 24 | |
22856bb8 | 25 | int tcpprintfs = 0; |
60b16fa9 | 26 | int tcpcksum = 1; |
4b935108 | 27 | struct tcpiphdr tcp_saveti; |
8b5a83bb | 28 | extern tcpnodelack; |
87e78f19 | 29 | |
4b935108 | 30 | struct tcpcb *tcp_newtcpcb(); |
2ff61f9d BJ |
31 | /* |
32 | * TCP input routine, follows pages 65-76 of the | |
33 | * protocol specification dated September, 1981 very closely. | |
34 | */ | |
2b4b57cd BJ |
35 | tcp_input(m0) |
36 | struct mbuf *m0; | |
87e78f19 | 37 | { |
2b4b57cd | 38 | register struct tcpiphdr *ti; |
53a5409e | 39 | struct inpcb *inp; |
2b4b57cd | 40 | register struct mbuf *m; |
8b5a83bb | 41 | struct mbuf *om = 0; |
2b4b57cd | 42 | int len, tlen, off; |
8e65fd66 | 43 | register struct tcpcb *tp = 0; |
2b4b57cd | 44 | register int tiflags; |
d52566dd | 45 | struct socket *so; |
f1b2fa5b | 46 | int todrop, acked; |
4b935108 | 47 | short ostate; |
ebcadd38 | 48 | struct in_addr laddr; |
87e78f19 BJ |
49 | |
50 | /* | |
4aed14e3 BJ |
51 | * Get IP and TCP header together in first mbuf. |
52 | * Note: IP leaves IP header in first mbuf. | |
87e78f19 | 53 | */ |
2b4b57cd | 54 | m = m0; |
20790db4 | 55 | ti = mtod(m, struct tcpiphdr *); |
4aed14e3 | 56 | if (((struct ip *)ti)->ip_hl > (sizeof (struct ip) >> 2)) |
d63599ac | 57 | ip_stripoptions((struct ip *)ti, (struct mbuf *)0); |
6703c41f BJ |
58 | if (m->m_off > MMAXOFF || m->m_len < sizeof (struct tcpiphdr)) { |
59 | if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) { | |
8a13b737 | 60 | tcpstat.tcps_hdrops++; |
6703c41f | 61 | return; |
8a13b737 BJ |
62 | } |
63 | ti = mtod(m, struct tcpiphdr *); | |
64 | } | |
87e78f19 | 65 | |
2b4b57cd | 66 | /* |
4aed14e3 | 67 | * Checksum extended TCP header and data. |
2b4b57cd BJ |
68 | */ |
69 | tlen = ((struct ip *)ti)->ip_len; | |
70 | len = sizeof (struct ip) + tlen; | |
60b16fa9 | 71 | if (tcpcksum) { |
2b4b57cd BJ |
72 | ti->ti_next = ti->ti_prev = 0; |
73 | ti->ti_x1 = 0; | |
ac83b17a | 74 | ti->ti_len = (u_short)tlen; |
668cc26d | 75 | ti->ti_len = htons((u_short)ti->ti_len); |
4b6b94ca | 76 | if (ti->ti_sum = in_cksum(m, len)) { |
2b4b57cd | 77 | tcpstat.tcps_badsum++; |
1e977657 BJ |
78 | if (tcpprintfs) |
79 | printf("tcp cksum %x\n", ti->ti_sum); | |
8a13b737 | 80 | goto drop; |
87e78f19 BJ |
81 | } |
82 | } | |
83 | ||
84 | /* | |
4aed14e3 | 85 | * Check that TCP offset makes sense, |
8b5a83bb | 86 | * pull out TCP options and adjust length. |
87e78f19 | 87 | */ |
2b4b57cd | 88 | off = ti->ti_off << 2; |
4b6b94ca | 89 | if (off < sizeof (struct tcphdr) || off > tlen) { |
2b4b57cd | 90 | tcpstat.tcps_badoff++; |
8a13b737 | 91 | goto drop; |
2b4b57cd | 92 | } |
1e977657 BJ |
93 | tlen -= off; |
94 | ti->ti_len = tlen; | |
8b5a83bb BJ |
95 | if (off > sizeof (struct tcphdr)) { |
96 | if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) { | |
97 | tcpstat.tcps_hdrops++; | |
98 | goto drop; | |
99 | } | |
100 | ti = mtod(m, struct tcpiphdr *); | |
101 | om = m_get(M_DONTWAIT); | |
102 | if (om == 0) | |
103 | goto drop; | |
8b5a83bb BJ |
104 | om->m_len = off - sizeof (struct tcphdr); |
105 | { caddr_t op = mtod(m, caddr_t) + sizeof (struct tcpiphdr); | |
668cc26d | 106 | bcopy(op, mtod(om, caddr_t), (unsigned)om->m_len); |
8b5a83bb | 107 | m->m_len -= om->m_len; |
668cc26d SL |
108 | bcopy(op+om->m_len, op, |
109 | (unsigned)(m->m_len-sizeof (struct tcpiphdr))); | |
8b5a83bb BJ |
110 | } |
111 | } | |
2ff61f9d | 112 | tiflags = ti->ti_flags; |
2b4b57cd | 113 | |
795e0416 | 114 | /* |
1e977657 | 115 | * Drop TCP and IP headers. |
795e0416 BJ |
116 | */ |
117 | off += sizeof (struct ip); | |
118 | m->m_off += off; | |
119 | m->m_len -= off; | |
120 | ||
8a13b737 | 121 | /* |
4aed14e3 | 122 | * Convert TCP protocol specific fields to host format. |
8a13b737 BJ |
123 | */ |
124 | ti->ti_seq = ntohl(ti->ti_seq); | |
125 | ti->ti_ack = ntohl(ti->ti_ack); | |
126 | ti->ti_win = ntohs(ti->ti_win); | |
127 | ti->ti_urp = ntohs(ti->ti_urp); | |
128 | ||
2b4b57cd | 129 | /* |
8075bb0e | 130 | * Locate pcb for segment. |
2b4b57cd | 131 | */ |
2ff61f9d | 132 | inp = in_pcblookup |
ebcadd38 BJ |
133 | (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport, |
134 | INPLOOKUP_WILDCARD); | |
2ff61f9d BJ |
135 | |
136 | /* | |
137 | * If the state is CLOSED (i.e., TCB does not exist) then | |
4aed14e3 | 138 | * all data in the incoming segment is discarded. |
2ff61f9d | 139 | */ |
22856bb8 | 140 | if (inp == 0) |
8a13b737 | 141 | goto dropwithreset; |
2ff61f9d | 142 | tp = intotcpcb(inp); |
22856bb8 | 143 | if (tp == 0) |
8a13b737 | 144 | goto dropwithreset; |
f1b2fa5b | 145 | so = inp->inp_socket; |
4b935108 BJ |
146 | if (so->so_options & SO_DEBUG) { |
147 | ostate = tp->t_state; | |
148 | tcp_saveti = *ti; | |
149 | } | |
ebf42a75 BJ |
150 | if (so->so_options & SO_ACCEPTCONN) { |
151 | so = sonewconn(so); | |
152 | if (so == 0) | |
153 | goto drop; | |
154 | inp = (struct inpcb *)so->so_pcb; | |
155 | inp->inp_laddr = ti->ti_dst; | |
156 | inp->inp_lport = ti->ti_dport; | |
157 | tp = intotcpcb(inp); | |
158 | tp->t_state = TCPS_LISTEN; | |
159 | } | |
87e78f19 | 160 | |
405c9168 BJ |
161 | /* |
162 | * Segment received on connection. | |
163 | * Reset idle time and keep-alive timer. | |
164 | */ | |
165 | tp->t_idle = 0; | |
166 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; | |
167 | ||
8b5a83bb BJ |
168 | /* |
169 | * Process options. | |
170 | */ | |
171 | if (om) { | |
172 | tcp_dooptions(tp, om); | |
173 | om = 0; | |
174 | } | |
175 | ||
87e78f19 | 176 | /* |
8a13b737 BJ |
177 | * Calculate amount of space in receive window, |
178 | * and then do TCP input processing. | |
87e78f19 | 179 | */ |
8a13b737 | 180 | tp->rcv_wnd = sbspace(&so->so_rcv); |
4b6b94ca BJ |
181 | if (tp->rcv_wnd < 0) |
182 | tp->rcv_wnd = 0; | |
2ff61f9d | 183 | |
87e78f19 BJ |
184 | switch (tp->t_state) { |
185 | ||
2ff61f9d BJ |
186 | /* |
187 | * If the state is LISTEN then ignore segment if it contains an RST. | |
188 | * If the segment contains an ACK then it is bad and send a RST. | |
189 | * If it does not contain a SYN then it is not interesting; drop it. | |
8a13b737 | 190 | * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial |
2ff61f9d | 191 | * tp->iss, and send a segment: |
8a13b737 | 192 | * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> |
2ff61f9d BJ |
193 | * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. |
194 | * Fill in remote peer address fields if not previously specified. | |
195 | * Enter SYN_RECEIVED state, and process any other fields of this | |
4aed14e3 | 196 | * segment in this state. |
2ff61f9d | 197 | */ |
8075bb0e | 198 | case TCPS_LISTEN: { |
a8d3bf7f | 199 | struct mbuf *am = m_get(M_DONTWAIT); |
8075bb0e BJ |
200 | register struct sockaddr_in *sin; |
201 | ||
a8d3bf7f | 202 | if (am == 0) |
8075bb0e | 203 | goto drop; |
a8d3bf7f | 204 | am->m_len = sizeof (struct sockaddr_in); |
2ff61f9d BJ |
205 | if (tiflags & TH_RST) |
206 | goto drop; | |
22856bb8 | 207 | if (tiflags & TH_ACK) |
8a13b737 | 208 | goto dropwithreset; |
22856bb8 | 209 | if ((tiflags & TH_SYN) == 0) |
2ff61f9d | 210 | goto drop; |
a8d3bf7f | 211 | sin = mtod(am, struct sockaddr_in *); |
8075bb0e BJ |
212 | sin->sin_family = AF_INET; |
213 | sin->sin_addr = ti->ti_src; | |
214 | sin->sin_port = ti->ti_sport; | |
ebcadd38 BJ |
215 | laddr = inp->inp_laddr; |
216 | if (inp->inp_laddr.s_addr == 0) | |
217 | inp->inp_laddr = ti->ti_dst; | |
a8d3bf7f | 218 | if (in_pcbconnect(inp, am)) { |
ebcadd38 | 219 | inp->inp_laddr = laddr; |
5a1f132a | 220 | (void) m_free(am); |
4aed14e3 | 221 | goto drop; |
ebcadd38 | 222 | } |
5a1f132a | 223 | (void) m_free(am); |
4aed14e3 BJ |
224 | tp->t_template = tcp_template(tp); |
225 | if (tp->t_template == 0) { | |
226 | in_pcbdisconnect(inp); | |
ebcadd38 | 227 | inp->inp_laddr = laddr; |
93f92b1d | 228 | tp = 0; |
4aed14e3 BJ |
229 | goto drop; |
230 | } | |
8a13b737 | 231 | tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; |
2ff61f9d | 232 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
233 | tcp_sendseqinit(tp); |
234 | tcp_rcvseqinit(tp); | |
2ff61f9d | 235 | tp->t_state = TCPS_SYN_RECEIVED; |
4aed14e3 | 236 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; |
8a13b737 | 237 | goto trimthenstep6; |
8075bb0e | 238 | } |
87e78f19 | 239 | |
2ff61f9d BJ |
240 | /* |
241 | * If the state is SYN_SENT: | |
242 | * if seg contains an ACK, but not for our SYN, drop the input. | |
243 | * if seg contains a RST, then drop the connection. | |
244 | * if seg does not contain SYN, then drop it. | |
245 | * Otherwise this is an acceptable SYN segment | |
246 | * initialize tp->rcv_nxt and tp->irs | |
247 | * if seg contains ack then advance tp->snd_una | |
248 | * if SYN has been acked change to ESTABLISHED else SYN_RCVD state | |
249 | * arrange for segment to be acked (eventually) | |
250 | * continue processing rest of data/controls, beginning with URG | |
251 | */ | |
252 | case TCPS_SYN_SENT: | |
253 | if ((tiflags & TH_ACK) && | |
22856bb8 BJ |
254 | /* this should be SEQ_LT; is SEQ_LEQ for BBN vax TCP only */ |
255 | (SEQ_LT(ti->ti_ack, tp->iss) || | |
4b6b94ca | 256 | SEQ_GT(ti->ti_ack, tp->snd_max))) |
8a13b737 | 257 | goto dropwithreset; |
2ff61f9d | 258 | if (tiflags & TH_RST) { |
93f92b1d | 259 | if (tiflags & TH_ACK) { |
4b935108 | 260 | tcp_drop(tp, ECONNREFUSED); |
93f92b1d BJ |
261 | tp = 0; |
262 | } | |
2ff61f9d | 263 | goto drop; |
87e78f19 | 264 | } |
2ff61f9d BJ |
265 | if ((tiflags & TH_SYN) == 0) |
266 | goto drop; | |
4b6b94ca | 267 | tp->snd_una = ti->ti_ack; |
b8977237 BJ |
268 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
269 | tp->snd_nxt = tp->snd_una; | |
4aed14e3 | 270 | tp->t_timer[TCPT_REXMT] = 0; |
2ff61f9d | 271 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
272 | tcp_rcvseqinit(tp); |
273 | tp->t_flags |= TF_ACKNOW; | |
405c9168 | 274 | if (SEQ_GT(tp->snd_una, tp->iss)) { |
4aed14e3 | 275 | soisconnected(so); |
2ff61f9d | 276 | tp->t_state = TCPS_ESTABLISHED; |
405c9168 BJ |
277 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
278 | } else | |
8a13b737 BJ |
279 | tp->t_state = TCPS_SYN_RECEIVED; |
280 | goto trimthenstep6; | |
281 | ||
282 | trimthenstep6: | |
283 | /* | |
4b6b94ca | 284 | * Advance ti->ti_seq to correspond to first data byte. |
8a13b737 BJ |
285 | * If data, trim to stay within window, |
286 | * dropping FIN if necessary. | |
287 | */ | |
4b6b94ca | 288 | ti->ti_seq++; |
8a13b737 BJ |
289 | if (ti->ti_len > tp->rcv_wnd) { |
290 | todrop = ti->ti_len - tp->rcv_wnd; | |
291 | m_adj(m, -todrop); | |
292 | ti->ti_len = tp->rcv_wnd; | |
293 | ti->ti_flags &= ~TH_FIN; | |
87e78f19 | 294 | } |
e832edbc | 295 | tp->snd_wl1 = ti->ti_seq - 1; |
8a13b737 | 296 | goto step6; |
2ff61f9d | 297 | } |
87e78f19 | 298 | |
2ff61f9d BJ |
299 | /* |
300 | * States other than LISTEN or SYN_SENT. | |
301 | * First check that at least some bytes of segment are within | |
302 | * receive window. | |
303 | */ | |
304 | if (tp->rcv_wnd == 0) { | |
305 | /* | |
306 | * If window is closed can only take segments at | |
4b6b94ca | 307 | * window edge, and have to drop data and PUSH from |
2ff61f9d BJ |
308 | * incoming segments. |
309 | */ | |
22856bb8 | 310 | if (tp->rcv_nxt != ti->ti_seq) |
2ff61f9d | 311 | goto dropafterack; |
8a13b737 | 312 | if (ti->ti_len > 0) { |
fd5dc5f0 | 313 | m_adj(m, ti->ti_len); |
8a13b737 BJ |
314 | ti->ti_len = 0; |
315 | ti->ti_flags &= ~(TH_PUSH|TH_FIN); | |
87e78f19 | 316 | } |
2ff61f9d BJ |
317 | } else { |
318 | /* | |
4b6b94ca | 319 | * If segment begins before rcv_nxt, drop leading |
2ff61f9d BJ |
320 | * data (and SYN); if nothing left, just ack. |
321 | */ | |
fd5dc5f0 BJ |
322 | todrop = tp->rcv_nxt - ti->ti_seq; |
323 | if (todrop > 0) { | |
8a13b737 | 324 | if (tiflags & TH_SYN) { |
22856bb8 | 325 | tiflags &= ~TH_SYN; |
fd5dc5f0 | 326 | ti->ti_flags &= ~TH_SYN; |
8a13b737 BJ |
327 | ti->ti_seq++; |
328 | if (ti->ti_urp > 1) | |
329 | ti->ti_urp--; | |
330 | else | |
331 | tiflags &= ~TH_URG; | |
332 | todrop--; | |
333 | } | |
1e977657 BJ |
334 | if (todrop > ti->ti_len || |
335 | todrop == ti->ti_len && (tiflags&TH_FIN) == 0) | |
2ff61f9d BJ |
336 | goto dropafterack; |
337 | m_adj(m, todrop); | |
338 | ti->ti_seq += todrop; | |
339 | ti->ti_len -= todrop; | |
8a13b737 BJ |
340 | if (ti->ti_urp > todrop) |
341 | ti->ti_urp -= todrop; | |
342 | else { | |
343 | tiflags &= ~TH_URG; | |
fd5dc5f0 BJ |
344 | ti->ti_flags &= ~TH_URG; |
345 | ti->ti_urp = 0; | |
8a13b737 | 346 | } |
2ff61f9d BJ |
347 | } |
348 | /* | |
349 | * If segment ends after window, drop trailing data | |
8a13b737 | 350 | * (and PUSH and FIN); if nothing left, just ACK. |
2ff61f9d | 351 | */ |
fd5dc5f0 BJ |
352 | todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); |
353 | if (todrop > 0) { | |
1e977657 | 354 | if (todrop >= ti->ti_len) |
2ff61f9d BJ |
355 | goto dropafterack; |
356 | m_adj(m, -todrop); | |
357 | ti->ti_len -= todrop; | |
8a13b737 | 358 | ti->ti_flags &= ~(TH_PUSH|TH_FIN); |
87e78f19 | 359 | } |
87e78f19 | 360 | } |
87e78f19 | 361 | |
dd020fc8 BJ |
362 | /* |
363 | * If a segment is received on a connection after the | |
364 | * user processes are gone, then RST the other end. | |
365 | */ | |
ebf42a75 | 366 | if (so->so_state & SS_NOFDREF) { |
dd020fc8 | 367 | tcp_close(tp); |
9d0b428a | 368 | tp = 0; |
dd020fc8 BJ |
369 | goto dropwithreset; |
370 | } | |
371 | ||
87e78f19 | 372 | /* |
2ff61f9d BJ |
373 | * If the RST bit is set examine the state: |
374 | * SYN_RECEIVED STATE: | |
375 | * If passive open, return to LISTEN state. | |
376 | * If active open, inform user that connection was refused. | |
377 | * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: | |
378 | * Inform user that connection was reset, and close tcb. | |
379 | * CLOSING, LAST_ACK, TIME_WAIT STATES | |
380 | * Close the tcb. | |
87e78f19 | 381 | */ |
2ff61f9d | 382 | if (tiflags&TH_RST) switch (tp->t_state) { |
4b935108 | 383 | |
2ff61f9d | 384 | case TCPS_SYN_RECEIVED: |
8a13b737 | 385 | tcp_drop(tp, ECONNREFUSED); |
93f92b1d | 386 | tp = 0; |
2ff61f9d BJ |
387 | goto drop; |
388 | ||
389 | case TCPS_ESTABLISHED: | |
390 | case TCPS_FIN_WAIT_1: | |
391 | case TCPS_FIN_WAIT_2: | |
392 | case TCPS_CLOSE_WAIT: | |
393 | tcp_drop(tp, ECONNRESET); | |
93f92b1d | 394 | tp = 0; |
2ff61f9d BJ |
395 | goto drop; |
396 | ||
397 | case TCPS_CLOSING: | |
398 | case TCPS_LAST_ACK: | |
399 | case TCPS_TIME_WAIT: | |
400 | tcp_close(tp); | |
93f92b1d | 401 | tp = 0; |
2ff61f9d | 402 | goto drop; |
87e78f19 | 403 | } |
87e78f19 BJ |
404 | |
405 | /* | |
2ff61f9d BJ |
406 | * If a SYN is in the window, then this is an |
407 | * error and we send an RST and drop the connection. | |
408 | */ | |
409 | if (tiflags & TH_SYN) { | |
4b6b94ca | 410 | tcp_drop(tp, ECONNRESET); |
9d0b428a | 411 | tp = 0; |
8a13b737 | 412 | goto dropwithreset; |
2ff61f9d BJ |
413 | } |
414 | ||
415 | /* | |
416 | * If the ACK bit is off we drop the segment and return. | |
417 | */ | |
8a13b737 | 418 | if ((tiflags & TH_ACK) == 0) |
2ff61f9d BJ |
419 | goto drop; |
420 | ||
421 | /* | |
422 | * Ack processing. | |
87e78f19 | 423 | */ |
87e78f19 BJ |
424 | switch (tp->t_state) { |
425 | ||
2ff61f9d BJ |
426 | /* |
427 | * In SYN_RECEIVED state if the ack ACKs our SYN then enter | |
428 | * ESTABLISHED state and continue processing, othewise | |
429 | * send an RST. | |
430 | */ | |
431 | case TCPS_SYN_RECEIVED: | |
8a13b737 | 432 | if (SEQ_GT(tp->snd_una, ti->ti_ack) || |
4b6b94ca | 433 | SEQ_GT(ti->ti_ack, tp->snd_max)) |
8a13b737 | 434 | goto dropwithreset; |
4aed14e3 | 435 | tp->snd_una++; /* SYN acked */ |
b8977237 BJ |
436 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
437 | tp->snd_nxt = tp->snd_una; | |
4aed14e3 | 438 | tp->t_timer[TCPT_REXMT] = 0; |
8a13b737 BJ |
439 | soisconnected(so); |
440 | tp->t_state = TCPS_ESTABLISHED; | |
405c9168 | 441 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
4aed14e3 | 442 | tp->snd_wl1 = ti->ti_seq - 1; |
8a13b737 | 443 | /* fall into ... */ |
87e78f19 | 444 | |
2ff61f9d BJ |
445 | /* |
446 | * In ESTABLISHED state: drop duplicate ACKs; ACK out of range | |
447 | * ACKs. If the ack is in the range | |
4b6b94ca | 448 | * tp->snd_una < ti->ti_ack <= tp->snd_max |
2ff61f9d BJ |
449 | * then advance tp->snd_una to ti->ti_ack and drop |
450 | * data from the retransmission queue. If this ACK reflects | |
451 | * more up to date window information we update our window information. | |
452 | */ | |
453 | case TCPS_ESTABLISHED: | |
454 | case TCPS_FIN_WAIT_1: | |
455 | case TCPS_FIN_WAIT_2: | |
456 | case TCPS_CLOSE_WAIT: | |
457 | case TCPS_CLOSING: | |
4aed14e3 BJ |
458 | case TCPS_LAST_ACK: |
459 | case TCPS_TIME_WAIT: | |
8a13b737 BJ |
460 | #define ourfinisacked (acked > 0) |
461 | ||
4aed14e3 | 462 | if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) |
2ff61f9d | 463 | break; |
22856bb8 | 464 | if (SEQ_GT(ti->ti_ack, tp->snd_max)) |
2ff61f9d | 465 | goto dropafterack; |
8a13b737 | 466 | acked = ti->ti_ack - tp->snd_una; |
dd020fc8 BJ |
467 | |
468 | /* | |
469 | * If transmit timer is running and timed sequence | |
470 | * number was acked, update smoothed round trip time. | |
471 | */ | |
472 | if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { | |
473 | if (tp->t_srtt == 0) | |
474 | tp->t_srtt = tp->t_rtt; | |
475 | else | |
476 | tp->t_srtt = | |
477 | tcp_alpha * tp->t_srtt + | |
478 | (1 - tcp_alpha) * tp->t_rtt; | |
479 | /* printf("rtt %d srtt*100 now %d\n", tp->t_rtt, (int)(tp->t_srtt*100)); */ | |
480 | tp->t_rtt = 0; | |
481 | } | |
482 | ||
6703c41f | 483 | if (ti->ti_ack == tp->snd_max) |
4aed14e3 | 484 | tp->t_timer[TCPT_REXMT] = 0; |
6703c41f | 485 | else { |
4aed14e3 BJ |
486 | TCPT_RANGESET(tp->t_timer[TCPT_REXMT], |
487 | tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); | |
dd020fc8 | 488 | tp->t_rtt = 1; |
22856bb8 | 489 | tp->t_rxtshift = 0; |
8a13b737 | 490 | } |
6703c41f BJ |
491 | if (acked > so->so_snd.sb_cc) { |
492 | sbdrop(&so->so_snd, so->so_snd.sb_cc); | |
493 | tp->snd_wnd -= so->so_snd.sb_cc; | |
494 | } else { | |
668cc26d | 495 | sbdrop(&so->so_snd, acked); |
6703c41f BJ |
496 | tp->snd_wnd -= acked; |
497 | acked = 0; | |
498 | } | |
5744ed2b | 499 | if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel) |
22856bb8 | 500 | sowwakeup(so); |
4b6b94ca | 501 | tp->snd_una = ti->ti_ack; |
b8977237 BJ |
502 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
503 | tp->snd_nxt = tp->snd_una; | |
405c9168 | 504 | |
87e78f19 BJ |
505 | switch (tp->t_state) { |
506 | ||
2ff61f9d BJ |
507 | /* |
508 | * In FIN_WAIT_1 STATE in addition to the processing | |
509 | * for the ESTABLISHED state if our FIN is now acknowledged | |
8a13b737 | 510 | * then enter FIN_WAIT_2. |
2ff61f9d BJ |
511 | */ |
512 | case TCPS_FIN_WAIT_1: | |
fdae4427 BJ |
513 | if (ourfinisacked) { |
514 | /* | |
515 | * If we can't receive any more | |
516 | * data, then closing user can proceed. | |
517 | */ | |
518 | if (so->so_state & SS_CANTRCVMORE) | |
519 | soisdisconnected(so); | |
8a13b737 | 520 | tp->t_state = TCPS_FIN_WAIT_2; |
fdae4427 | 521 | } |
87e78f19 BJ |
522 | break; |
523 | ||
2ff61f9d BJ |
524 | /* |
525 | * In CLOSING STATE in addition to the processing for | |
526 | * the ESTABLISHED state if the ACK acknowledges our FIN | |
527 | * then enter the TIME-WAIT state, otherwise ignore | |
528 | * the segment. | |
529 | */ | |
530 | case TCPS_CLOSING: | |
4aed14e3 | 531 | if (ourfinisacked) { |
2ff61f9d | 532 | tp->t_state = TCPS_TIME_WAIT; |
4aed14e3 BJ |
533 | tcp_canceltimers(tp); |
534 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; | |
535 | soisdisconnected(so); | |
536 | } | |
537 | break; | |
87e78f19 | 538 | |
2ff61f9d | 539 | /* |
8a13b737 BJ |
540 | * The only thing that can arrive in LAST_ACK state |
541 | * is an acknowledgment of our FIN. If our FIN is now | |
542 | * acknowledged, delete the TCB, enter the closed state | |
543 | * and return. | |
2ff61f9d BJ |
544 | */ |
545 | case TCPS_LAST_ACK: | |
93f92b1d | 546 | if (ourfinisacked) { |
2ff61f9d | 547 | tcp_close(tp); |
93f92b1d BJ |
548 | tp = 0; |
549 | } | |
2ff61f9d | 550 | goto drop; |
87e78f19 | 551 | |
2ff61f9d BJ |
552 | /* |
553 | * In TIME_WAIT state the only thing that should arrive | |
554 | * is a retransmission of the remote FIN. Acknowledge | |
555 | * it and restart the finack timer. | |
556 | */ | |
557 | case TCPS_TIME_WAIT: | |
405c9168 | 558 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 559 | goto dropafterack; |
87e78f19 | 560 | } |
8a13b737 BJ |
561 | #undef ourfinisacked |
562 | } | |
87e78f19 | 563 | |
2ff61f9d | 564 | step6: |
4aed14e3 BJ |
565 | /* |
566 | * Update window information. | |
567 | */ | |
22856bb8 | 568 | if (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && |
8e65fd66 | 569 | (SEQ_LT(tp->snd_wl2, ti->ti_ack) || |
22856bb8 | 570 | tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd)) { |
4aed14e3 BJ |
571 | tp->snd_wnd = ti->ti_win; |
572 | tp->snd_wl1 = ti->ti_seq; | |
573 | tp->snd_wl2 = ti->ti_ack; | |
a8d3bf7f | 574 | if (tp->snd_wnd != 0) |
4aed14e3 BJ |
575 | tp->t_timer[TCPT_PERSIST] = 0; |
576 | } | |
4aed14e3 | 577 | |
2ff61f9d | 578 | /* |
b2db9217 | 579 | * Process segments with URG. |
2ff61f9d | 580 | */ |
9c811062 BJ |
581 | if ((tiflags & TH_URG) && ti->ti_urp && |
582 | TCPS_HAVERCVDFIN(tp->t_state) == 0) { | |
b2db9217 BJ |
583 | /* |
584 | * If this segment advances the known urgent pointer, | |
585 | * then mark the data stream. This should not happen | |
586 | * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since | |
587 | * a FIN has been received from the remote side. | |
588 | * In these states we ignore the URG. | |
589 | */ | |
590 | if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { | |
591 | tp->rcv_up = ti->ti_seq + ti->ti_urp; | |
592 | so->so_oobmark = so->so_rcv.sb_cc + | |
593 | (tp->rcv_up - tp->rcv_nxt) - 1; | |
594 | if (so->so_oobmark == 0) | |
595 | so->so_state |= SS_RCVATMARK; | |
77a4e3ca | 596 | sohasoutofband(so); |
b2db9217 BJ |
597 | tp->t_oobflags &= ~TCPOOB_HAVEDATA; |
598 | } | |
599 | /* | |
600 | * Remove out of band data so doesn't get presented to user. | |
601 | * This can happen independent of advancing the URG pointer, | |
602 | * but if two URG's are pending at once, some out-of-band | |
603 | * data may creep in... ick. | |
604 | */ | |
ebf42a75 | 605 | if (ti->ti_urp <= ti->ti_len) |
b2db9217 | 606 | tcp_pulloutofband(so, ti); |
5e74df82 | 607 | } |
87e78f19 BJ |
608 | |
609 | /* | |
2ff61f9d BJ |
610 | * Process the segment text, merging it into the TCP sequencing queue, |
611 | * and arranging for acknowledgment of receipt if necessary. | |
612 | * This process logically involves adjusting tp->rcv_wnd as data | |
613 | * is presented to the user (this happens in tcp_usrreq.c, | |
614 | * case PRU_RCVD). If a FIN has already been received on this | |
615 | * connection then we just ignore the text. | |
87e78f19 | 616 | */ |
e832edbc BJ |
617 | if ((ti->ti_len || (tiflags&TH_FIN)) && |
618 | TCPS_HAVERCVDFIN(tp->t_state) == 0) { | |
2ff61f9d | 619 | tiflags = tcp_reass(tp, ti); |
8b5a83bb BJ |
620 | if (tcpnodelack == 0) |
621 | tp->t_flags |= TF_DELACK; | |
622 | else | |
623 | tp->t_flags |= TF_ACKNOW; | |
4aed14e3 | 624 | } else { |
2b4b57cd | 625 | m_freem(m); |
e832edbc | 626 | tiflags &= ~TH_FIN; |
4aed14e3 | 627 | } |
87e78f19 BJ |
628 | |
629 | /* | |
e832edbc BJ |
630 | * If FIN is received ACK the FIN and let the user know |
631 | * that the connection is closing. | |
87e78f19 | 632 | */ |
e832edbc | 633 | if (tiflags & TH_FIN) { |
4aed14e3 BJ |
634 | if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { |
635 | socantrcvmore(so); | |
636 | tp->t_flags |= TF_ACKNOW; | |
637 | tp->rcv_nxt++; | |
638 | } | |
2ff61f9d | 639 | switch (tp->t_state) { |
87e78f19 | 640 | |
2ff61f9d BJ |
641 | /* |
642 | * In SYN_RECEIVED and ESTABLISHED STATES | |
643 | * enter the CLOSE_WAIT state. | |
53a5409e | 644 | */ |
2ff61f9d BJ |
645 | case TCPS_SYN_RECEIVED: |
646 | case TCPS_ESTABLISHED: | |
647 | tp->t_state = TCPS_CLOSE_WAIT; | |
648 | break; | |
53a5409e | 649 | |
2ff61f9d | 650 | /* |
8a13b737 BJ |
651 | * If still in FIN_WAIT_1 STATE FIN has not been acked so |
652 | * enter the CLOSING state. | |
53a5409e | 653 | */ |
2ff61f9d | 654 | case TCPS_FIN_WAIT_1: |
8a13b737 | 655 | tp->t_state = TCPS_CLOSING; |
2ff61f9d | 656 | break; |
87e78f19 | 657 | |
2ff61f9d BJ |
658 | /* |
659 | * In FIN_WAIT_2 state enter the TIME_WAIT state, | |
660 | * starting the time-wait timer, turning off the other | |
661 | * standard timers. | |
662 | */ | |
663 | case TCPS_FIN_WAIT_2: | |
4aed14e3 | 664 | tp->t_state = TCPS_TIME_WAIT; |
a6503abf | 665 | tcp_canceltimers(tp); |
405c9168 | 666 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
4aed14e3 | 667 | soisdisconnected(so); |
2ff61f9d BJ |
668 | break; |
669 | ||
53a5409e | 670 | /* |
2ff61f9d | 671 | * In TIME_WAIT state restart the 2 MSL time_wait timer. |
53a5409e | 672 | */ |
2ff61f9d | 673 | case TCPS_TIME_WAIT: |
405c9168 | 674 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 675 | break; |
8a13b737 | 676 | } |
87e78f19 | 677 | } |
4b935108 BJ |
678 | if (so->so_options & SO_DEBUG) |
679 | tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); | |
8a13b737 BJ |
680 | |
681 | /* | |
682 | * Return any desired output. | |
683 | */ | |
668cc26d | 684 | (void) tcp_output(tp); |
2ff61f9d | 685 | return; |
8a13b737 | 686 | |
2ff61f9d | 687 | dropafterack: |
8a13b737 | 688 | /* |
1e977657 BJ |
689 | * Generate an ACK dropping incoming segment if it occupies |
690 | * sequence space, where the ACK reflects our state. | |
8a13b737 | 691 | */ |
1e977657 BJ |
692 | if ((tiflags&TH_RST) || |
693 | tlen == 0 && (tiflags&(TH_SYN|TH_FIN)) == 0) | |
8a13b737 | 694 | goto drop; |
f3cdd721 BJ |
695 | if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG) |
696 | tcp_trace(TA_RESPOND, ostate, tp, &tcp_saveti, 0); | |
8e65fd66 | 697 | tcp_respond(tp, ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK); |
4b6b94ca | 698 | return; |
8a13b737 BJ |
699 | |
700 | dropwithreset: | |
8b5a83bb | 701 | if (om) |
668cc26d | 702 | (void) m_free(om); |
8a13b737 | 703 | /* |
4aed14e3 | 704 | * Generate a RST, dropping incoming segment. |
8a13b737 BJ |
705 | * Make ACK acceptable to originator of segment. |
706 | */ | |
707 | if (tiflags & TH_RST) | |
708 | goto drop; | |
709 | if (tiflags & TH_ACK) | |
8e65fd66 | 710 | tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); |
8a13b737 BJ |
711 | else { |
712 | if (tiflags & TH_SYN) | |
713 | ti->ti_len++; | |
1e977657 BJ |
714 | tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, |
715 | TH_RST|TH_ACK); | |
8a13b737 | 716 | } |
4b6b94ca | 717 | return; |
8a13b737 | 718 | |
2ff61f9d | 719 | drop: |
8a13b737 BJ |
720 | /* |
721 | * Drop space held by incoming segment and return. | |
722 | */ | |
f3cdd721 BJ |
723 | if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) |
724 | tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); | |
2ff61f9d | 725 | m_freem(m); |
4b935108 | 726 | return; |
2ff61f9d BJ |
727 | } |
728 | ||
8b5a83bb BJ |
729 | tcp_dooptions(tp, om) |
730 | struct tcpcb *tp; | |
731 | struct mbuf *om; | |
5e74df82 | 732 | { |
8b5a83bb BJ |
733 | register u_char *cp; |
734 | int opt, optlen, cnt; | |
735 | ||
736 | cp = mtod(om, u_char *); | |
737 | cnt = om->m_len; | |
738 | for (; cnt > 0; cnt -= optlen, cp += optlen) { | |
739 | opt = cp[0]; | |
740 | if (opt == TCPOPT_EOL) | |
741 | break; | |
742 | if (opt == TCPOPT_NOP) | |
743 | optlen = 1; | |
744 | else | |
745 | optlen = cp[1]; | |
746 | switch (opt) { | |
747 | ||
748 | default: | |
749 | break; | |
750 | ||
751 | case TCPOPT_MAXSEG: | |
752 | if (optlen != 4) | |
753 | continue; | |
754 | tp->t_maxseg = *(u_short *)(cp + 2); | |
668cc26d | 755 | tp->t_maxseg = ntohs((u_short)tp->t_maxseg); |
8b5a83bb | 756 | break; |
8b5a83bb | 757 | } |
5e74df82 | 758 | } |
668cc26d | 759 | (void) m_free(om); |
5e74df82 BJ |
760 | } |
761 | ||
b2db9217 BJ |
762 | /* |
763 | * Pull out of band byte out of a segment so | |
764 | * it doesn't appear in the user's data queue. | |
765 | * It is still reflected in the segment length for | |
766 | * sequencing purposes. | |
767 | */ | |
768 | tcp_pulloutofband(so, ti) | |
769 | struct socket *so; | |
770 | struct tcpiphdr *ti; | |
771 | { | |
772 | register struct mbuf *m; | |
1acff8ec | 773 | int cnt = ti->ti_urp - 1; |
b2db9217 BJ |
774 | |
775 | m = dtom(ti); | |
776 | while (cnt >= 0) { | |
777 | if (m->m_len > cnt) { | |
778 | char *cp = mtod(m, caddr_t) + cnt; | |
779 | struct tcpcb *tp = sototcpcb(so); | |
780 | ||
781 | tp->t_iobc = *cp; | |
782 | tp->t_oobflags |= TCPOOB_HAVEDATA; | |
668cc26d | 783 | bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); |
b2db9217 BJ |
784 | m->m_len--; |
785 | return; | |
786 | } | |
787 | cnt -= m->m_len; | |
788 | m = m->m_next; | |
789 | if (m == 0) | |
790 | break; | |
791 | } | |
792 | panic("tcp_pulloutofband"); | |
793 | } | |
794 | ||
2ff61f9d BJ |
795 | /* |
796 | * Insert segment ti into reassembly queue of tcp with | |
797 | * control block tp. Return TH_FIN if reassembly now includes | |
798 | * a segment with FIN. | |
799 | */ | |
f1b2fa5b | 800 | tcp_reass(tp, ti) |
2ff61f9d BJ |
801 | register struct tcpcb *tp; |
802 | register struct tcpiphdr *ti; | |
2ff61f9d BJ |
803 | { |
804 | register struct tcpiphdr *q; | |
8a13b737 | 805 | struct socket *so = tp->t_inpcb->inp_socket; |
e832edbc BJ |
806 | struct mbuf *m; |
807 | int flags; | |
2ff61f9d BJ |
808 | |
809 | /* | |
405c9168 BJ |
810 | * Call with ti==0 after become established to |
811 | * force pre-ESTABLISHED data up to user socket. | |
2ff61f9d | 812 | */ |
405c9168 | 813 | if (ti == 0) |
2ff61f9d | 814 | goto present; |
87e78f19 | 815 | |
2ff61f9d BJ |
816 | /* |
817 | * Find a segment which begins after this one does. | |
818 | */ | |
819 | for (q = tp->seg_next; q != (struct tcpiphdr *)tp; | |
820 | q = (struct tcpiphdr *)q->ti_next) | |
821 | if (SEQ_GT(q->ti_seq, ti->ti_seq)) | |
822 | break; | |
823 | ||
824 | /* | |
825 | * If there is a preceding segment, it may provide some of | |
826 | * our data already. If so, drop the data from the incoming | |
827 | * segment. If it provides all of our data, drop us. | |
828 | */ | |
829 | if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { | |
830 | register int i; | |
fd5dc5f0 | 831 | q = (struct tcpiphdr *)q->ti_prev; |
2ff61f9d BJ |
832 | /* conversion to int (in i) handles seq wraparound */ |
833 | i = q->ti_seq + q->ti_len - ti->ti_seq; | |
834 | if (i > 0) { | |
2b4b57cd | 835 | if (i >= ti->ti_len) |
2ff61f9d | 836 | goto drop; |
4ab1a5c3 | 837 | m_adj(dtom(ti), i); |
2b4b57cd | 838 | ti->ti_len -= i; |
2ff61f9d | 839 | ti->ti_seq += i; |
53a5409e | 840 | } |
2ff61f9d BJ |
841 | q = (struct tcpiphdr *)(q->ti_next); |
842 | } | |
87e78f19 | 843 | |
2ff61f9d BJ |
844 | /* |
845 | * While we overlap succeeding segments trim them or, | |
846 | * if they are completely covered, dequeue them. | |
847 | */ | |
fd5dc5f0 | 848 | while (q != (struct tcpiphdr *)tp) { |
2ff61f9d | 849 | register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; |
fd5dc5f0 BJ |
850 | if (i <= 0) |
851 | break; | |
2ff61f9d | 852 | if (i < q->ti_len) { |
fd5dc5f0 | 853 | q->ti_seq += i; |
2ff61f9d BJ |
854 | q->ti_len -= i; |
855 | m_adj(dtom(q), i); | |
856 | break; | |
ac5e71a1 | 857 | } |
2ff61f9d | 858 | q = (struct tcpiphdr *)q->ti_next; |
473a17a5 | 859 | m = dtom(q->ti_prev); |
2ff61f9d | 860 | remque(q->ti_prev); |
473a17a5 | 861 | m_freem(m); |
2ff61f9d | 862 | } |
87e78f19 | 863 | |
2ff61f9d BJ |
864 | /* |
865 | * Stick new segment in its place. | |
866 | */ | |
867 | insque(ti, q->ti_prev); | |
2ff61f9d | 868 | |
2ff61f9d BJ |
869 | present: |
870 | /* | |
4aed14e3 BJ |
871 | * Present data to user, advancing rcv_nxt through |
872 | * completed sequence space. | |
2ff61f9d | 873 | */ |
e832edbc | 874 | if (TCPS_HAVERCVDSYN(tp->t_state) == 0) |
4aed14e3 | 875 | return (0); |
2b4b57cd | 876 | ti = tp->seg_next; |
e832edbc BJ |
877 | if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) |
878 | return (0); | |
879 | if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) | |
880 | return (0); | |
881 | do { | |
4aed14e3 BJ |
882 | tp->rcv_nxt += ti->ti_len; |
883 | flags = ti->ti_flags & TH_FIN; | |
2b4b57cd | 884 | remque(ti); |
e832edbc | 885 | m = dtom(ti); |
2b4b57cd | 886 | ti = (struct tcpiphdr *)ti->ti_next; |
e832edbc | 887 | if (so->so_state & SS_CANTRCVMORE) |
668cc26d | 888 | m_freem(m); |
599c842e BJ |
889 | else { |
890 | SBCHECK(&so->so_rcv, "tcp_input before"); | |
e832edbc | 891 | sbappend(&so->so_rcv, m); |
599c842e BJ |
892 | SBCHECK(&so->so_rcv, "tcp_input after"); |
893 | } | |
e832edbc BJ |
894 | } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); |
895 | sorwakeup(so); | |
2ff61f9d BJ |
896 | return (flags); |
897 | drop: | |
898 | m_freem(dtom(ti)); | |
e832edbc | 899 | return (0); |
d52566dd | 900 | } |