Commit | Line | Data |
---|---|---|
c9f1e449 | 1 | /* tcp_input.c 1.86 83/01/08 */ |
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 *); | |
cce93e4b | 101 | om = m_get(M_DONTWAIT, MT_DATA); |
8b5a83bb BJ |
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: { |
789d2a39 | 199 | struct mbuf *am; |
8075bb0e BJ |
200 | register struct sockaddr_in *sin; |
201 | ||
2ff61f9d BJ |
202 | if (tiflags & TH_RST) |
203 | goto drop; | |
22856bb8 | 204 | if (tiflags & TH_ACK) |
8a13b737 | 205 | goto dropwithreset; |
22856bb8 | 206 | if ((tiflags & TH_SYN) == 0) |
2ff61f9d | 207 | goto drop; |
789d2a39 SL |
208 | am = m_get(M_DONTWAIT, MT_SONAME); |
209 | if (am == NULL) | |
210 | goto drop; | |
211 | am->m_len = sizeof (struct sockaddr_in); | |
a8d3bf7f | 212 | sin = mtod(am, struct sockaddr_in *); |
8075bb0e BJ |
213 | sin->sin_family = AF_INET; |
214 | sin->sin_addr = ti->ti_src; | |
215 | sin->sin_port = ti->ti_sport; | |
ebcadd38 | 216 | laddr = inp->inp_laddr; |
789d2a39 | 217 | if (inp->inp_laddr.s_addr == INADDR_ANY) |
ebcadd38 | 218 | inp->inp_laddr = ti->ti_dst; |
a8d3bf7f | 219 | if (in_pcbconnect(inp, am)) { |
ebcadd38 | 220 | inp->inp_laddr = laddr; |
5a1f132a | 221 | (void) m_free(am); |
4aed14e3 | 222 | goto drop; |
ebcadd38 | 223 | } |
5a1f132a | 224 | (void) m_free(am); |
4aed14e3 BJ |
225 | tp->t_template = tcp_template(tp); |
226 | if (tp->t_template == 0) { | |
227 | in_pcbdisconnect(inp); | |
ebcadd38 | 228 | inp->inp_laddr = laddr; |
93f92b1d | 229 | tp = 0; |
4aed14e3 BJ |
230 | goto drop; |
231 | } | |
8a13b737 | 232 | tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; |
2ff61f9d | 233 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
234 | tcp_sendseqinit(tp); |
235 | tcp_rcvseqinit(tp); | |
2ff61f9d | 236 | tp->t_state = TCPS_SYN_RECEIVED; |
4aed14e3 | 237 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; |
8a13b737 | 238 | goto trimthenstep6; |
8075bb0e | 239 | } |
87e78f19 | 240 | |
2ff61f9d BJ |
241 | /* |
242 | * If the state is SYN_SENT: | |
243 | * if seg contains an ACK, but not for our SYN, drop the input. | |
244 | * if seg contains a RST, then drop the connection. | |
245 | * if seg does not contain SYN, then drop it. | |
246 | * Otherwise this is an acceptable SYN segment | |
247 | * initialize tp->rcv_nxt and tp->irs | |
248 | * if seg contains ack then advance tp->snd_una | |
249 | * if SYN has been acked change to ESTABLISHED else SYN_RCVD state | |
250 | * arrange for segment to be acked (eventually) | |
251 | * continue processing rest of data/controls, beginning with URG | |
252 | */ | |
253 | case TCPS_SYN_SENT: | |
254 | if ((tiflags & TH_ACK) && | |
22856bb8 BJ |
255 | /* this should be SEQ_LT; is SEQ_LEQ for BBN vax TCP only */ |
256 | (SEQ_LT(ti->ti_ack, tp->iss) || | |
4b6b94ca | 257 | SEQ_GT(ti->ti_ack, tp->snd_max))) |
8a13b737 | 258 | goto dropwithreset; |
2ff61f9d | 259 | if (tiflags & TH_RST) { |
93f92b1d | 260 | if (tiflags & TH_ACK) { |
4b935108 | 261 | tcp_drop(tp, ECONNREFUSED); |
93f92b1d BJ |
262 | tp = 0; |
263 | } | |
2ff61f9d | 264 | goto drop; |
87e78f19 | 265 | } |
2ff61f9d BJ |
266 | if ((tiflags & TH_SYN) == 0) |
267 | goto drop; | |
4b6b94ca | 268 | tp->snd_una = ti->ti_ack; |
b8977237 BJ |
269 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
270 | tp->snd_nxt = tp->snd_una; | |
4aed14e3 | 271 | tp->t_timer[TCPT_REXMT] = 0; |
2ff61f9d | 272 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
273 | tcp_rcvseqinit(tp); |
274 | tp->t_flags |= TF_ACKNOW; | |
405c9168 | 275 | if (SEQ_GT(tp->snd_una, tp->iss)) { |
4aed14e3 | 276 | soisconnected(so); |
2ff61f9d | 277 | tp->t_state = TCPS_ESTABLISHED; |
405c9168 BJ |
278 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
279 | } else | |
8a13b737 BJ |
280 | tp->t_state = TCPS_SYN_RECEIVED; |
281 | goto trimthenstep6; | |
282 | ||
283 | trimthenstep6: | |
284 | /* | |
4b6b94ca | 285 | * Advance ti->ti_seq to correspond to first data byte. |
8a13b737 BJ |
286 | * If data, trim to stay within window, |
287 | * dropping FIN if necessary. | |
288 | */ | |
4b6b94ca | 289 | ti->ti_seq++; |
8a13b737 BJ |
290 | if (ti->ti_len > tp->rcv_wnd) { |
291 | todrop = ti->ti_len - tp->rcv_wnd; | |
292 | m_adj(m, -todrop); | |
293 | ti->ti_len = tp->rcv_wnd; | |
294 | ti->ti_flags &= ~TH_FIN; | |
87e78f19 | 295 | } |
e832edbc | 296 | tp->snd_wl1 = ti->ti_seq - 1; |
8a13b737 | 297 | goto step6; |
2ff61f9d | 298 | } |
87e78f19 | 299 | |
2ff61f9d BJ |
300 | /* |
301 | * States other than LISTEN or SYN_SENT. | |
302 | * First check that at least some bytes of segment are within | |
303 | * receive window. | |
304 | */ | |
305 | if (tp->rcv_wnd == 0) { | |
306 | /* | |
307 | * If window is closed can only take segments at | |
4b6b94ca | 308 | * window edge, and have to drop data and PUSH from |
2ff61f9d BJ |
309 | * incoming segments. |
310 | */ | |
22856bb8 | 311 | if (tp->rcv_nxt != ti->ti_seq) |
2ff61f9d | 312 | goto dropafterack; |
8a13b737 | 313 | if (ti->ti_len > 0) { |
fd5dc5f0 | 314 | m_adj(m, ti->ti_len); |
8a13b737 BJ |
315 | ti->ti_len = 0; |
316 | ti->ti_flags &= ~(TH_PUSH|TH_FIN); | |
87e78f19 | 317 | } |
2ff61f9d BJ |
318 | } else { |
319 | /* | |
4b6b94ca | 320 | * If segment begins before rcv_nxt, drop leading |
2ff61f9d BJ |
321 | * data (and SYN); if nothing left, just ack. |
322 | */ | |
fd5dc5f0 BJ |
323 | todrop = tp->rcv_nxt - ti->ti_seq; |
324 | if (todrop > 0) { | |
8a13b737 | 325 | if (tiflags & TH_SYN) { |
22856bb8 | 326 | tiflags &= ~TH_SYN; |
fd5dc5f0 | 327 | ti->ti_flags &= ~TH_SYN; |
8a13b737 BJ |
328 | ti->ti_seq++; |
329 | if (ti->ti_urp > 1) | |
330 | ti->ti_urp--; | |
331 | else | |
332 | tiflags &= ~TH_URG; | |
333 | todrop--; | |
334 | } | |
1e977657 BJ |
335 | if (todrop > ti->ti_len || |
336 | todrop == ti->ti_len && (tiflags&TH_FIN) == 0) | |
2ff61f9d BJ |
337 | goto dropafterack; |
338 | m_adj(m, todrop); | |
339 | ti->ti_seq += todrop; | |
340 | ti->ti_len -= todrop; | |
8a13b737 BJ |
341 | if (ti->ti_urp > todrop) |
342 | ti->ti_urp -= todrop; | |
343 | else { | |
344 | tiflags &= ~TH_URG; | |
fd5dc5f0 BJ |
345 | ti->ti_flags &= ~TH_URG; |
346 | ti->ti_urp = 0; | |
8a13b737 | 347 | } |
2ff61f9d BJ |
348 | } |
349 | /* | |
350 | * If segment ends after window, drop trailing data | |
8a13b737 | 351 | * (and PUSH and FIN); if nothing left, just ACK. |
2ff61f9d | 352 | */ |
fd5dc5f0 BJ |
353 | todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); |
354 | if (todrop > 0) { | |
1e977657 | 355 | if (todrop >= ti->ti_len) |
2ff61f9d BJ |
356 | goto dropafterack; |
357 | m_adj(m, -todrop); | |
358 | ti->ti_len -= todrop; | |
8a13b737 | 359 | ti->ti_flags &= ~(TH_PUSH|TH_FIN); |
87e78f19 | 360 | } |
87e78f19 | 361 | } |
87e78f19 | 362 | |
dd020fc8 | 363 | /* |
6fed2989 | 364 | * If data is received on a connection after the |
dd020fc8 BJ |
365 | * user processes are gone, then RST the other end. |
366 | */ | |
c9f1e449 SL |
367 | if (so->so_state & SS_NOFDREF && tp->t_state > TCPS_CLOSE_WAIT && |
368 | ti->ti_len) { | |
dd020fc8 | 369 | tcp_close(tp); |
9d0b428a | 370 | tp = 0; |
dd020fc8 BJ |
371 | goto dropwithreset; |
372 | } | |
373 | ||
87e78f19 | 374 | /* |
2ff61f9d BJ |
375 | * If the RST bit is set examine the state: |
376 | * SYN_RECEIVED STATE: | |
377 | * If passive open, return to LISTEN state. | |
378 | * If active open, inform user that connection was refused. | |
379 | * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: | |
380 | * Inform user that connection was reset, and close tcb. | |
381 | * CLOSING, LAST_ACK, TIME_WAIT STATES | |
382 | * Close the tcb. | |
87e78f19 | 383 | */ |
2ff61f9d | 384 | if (tiflags&TH_RST) switch (tp->t_state) { |
4b935108 | 385 | |
2ff61f9d | 386 | case TCPS_SYN_RECEIVED: |
8a13b737 | 387 | tcp_drop(tp, ECONNREFUSED); |
93f92b1d | 388 | tp = 0; |
2ff61f9d BJ |
389 | goto drop; |
390 | ||
391 | case TCPS_ESTABLISHED: | |
392 | case TCPS_FIN_WAIT_1: | |
393 | case TCPS_FIN_WAIT_2: | |
394 | case TCPS_CLOSE_WAIT: | |
395 | tcp_drop(tp, ECONNRESET); | |
93f92b1d | 396 | tp = 0; |
2ff61f9d BJ |
397 | goto drop; |
398 | ||
399 | case TCPS_CLOSING: | |
400 | case TCPS_LAST_ACK: | |
401 | case TCPS_TIME_WAIT: | |
402 | tcp_close(tp); | |
93f92b1d | 403 | tp = 0; |
2ff61f9d | 404 | goto drop; |
87e78f19 | 405 | } |
87e78f19 BJ |
406 | |
407 | /* | |
2ff61f9d BJ |
408 | * If a SYN is in the window, then this is an |
409 | * error and we send an RST and drop the connection. | |
410 | */ | |
411 | if (tiflags & TH_SYN) { | |
4b6b94ca | 412 | tcp_drop(tp, ECONNRESET); |
9d0b428a | 413 | tp = 0; |
8a13b737 | 414 | goto dropwithreset; |
2ff61f9d BJ |
415 | } |
416 | ||
417 | /* | |
418 | * If the ACK bit is off we drop the segment and return. | |
419 | */ | |
8a13b737 | 420 | if ((tiflags & TH_ACK) == 0) |
2ff61f9d BJ |
421 | goto drop; |
422 | ||
423 | /* | |
424 | * Ack processing. | |
87e78f19 | 425 | */ |
87e78f19 BJ |
426 | switch (tp->t_state) { |
427 | ||
2ff61f9d BJ |
428 | /* |
429 | * In SYN_RECEIVED state if the ack ACKs our SYN then enter | |
430 | * ESTABLISHED state and continue processing, othewise | |
431 | * send an RST. | |
432 | */ | |
433 | case TCPS_SYN_RECEIVED: | |
8a13b737 | 434 | if (SEQ_GT(tp->snd_una, ti->ti_ack) || |
4b6b94ca | 435 | SEQ_GT(ti->ti_ack, tp->snd_max)) |
8a13b737 | 436 | goto dropwithreset; |
4aed14e3 | 437 | tp->snd_una++; /* SYN acked */ |
b8977237 BJ |
438 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
439 | tp->snd_nxt = tp->snd_una; | |
4aed14e3 | 440 | tp->t_timer[TCPT_REXMT] = 0; |
8a13b737 BJ |
441 | soisconnected(so); |
442 | tp->t_state = TCPS_ESTABLISHED; | |
405c9168 | 443 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
4aed14e3 | 444 | tp->snd_wl1 = ti->ti_seq - 1; |
8a13b737 | 445 | /* fall into ... */ |
87e78f19 | 446 | |
2ff61f9d BJ |
447 | /* |
448 | * In ESTABLISHED state: drop duplicate ACKs; ACK out of range | |
449 | * ACKs. If the ack is in the range | |
4b6b94ca | 450 | * tp->snd_una < ti->ti_ack <= tp->snd_max |
2ff61f9d BJ |
451 | * then advance tp->snd_una to ti->ti_ack and drop |
452 | * data from the retransmission queue. If this ACK reflects | |
453 | * more up to date window information we update our window information. | |
454 | */ | |
455 | case TCPS_ESTABLISHED: | |
456 | case TCPS_FIN_WAIT_1: | |
457 | case TCPS_FIN_WAIT_2: | |
458 | case TCPS_CLOSE_WAIT: | |
459 | case TCPS_CLOSING: | |
4aed14e3 BJ |
460 | case TCPS_LAST_ACK: |
461 | case TCPS_TIME_WAIT: | |
8a13b737 BJ |
462 | #define ourfinisacked (acked > 0) |
463 | ||
4aed14e3 | 464 | if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) |
2ff61f9d | 465 | break; |
22856bb8 | 466 | if (SEQ_GT(ti->ti_ack, tp->snd_max)) |
2ff61f9d | 467 | goto dropafterack; |
8a13b737 | 468 | acked = ti->ti_ack - tp->snd_una; |
dd020fc8 BJ |
469 | |
470 | /* | |
471 | * If transmit timer is running and timed sequence | |
472 | * number was acked, update smoothed round trip time. | |
473 | */ | |
474 | if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { | |
475 | if (tp->t_srtt == 0) | |
476 | tp->t_srtt = tp->t_rtt; | |
477 | else | |
478 | tp->t_srtt = | |
479 | tcp_alpha * tp->t_srtt + | |
480 | (1 - tcp_alpha) * tp->t_rtt; | |
dd020fc8 BJ |
481 | tp->t_rtt = 0; |
482 | } | |
483 | ||
6703c41f | 484 | if (ti->ti_ack == tp->snd_max) |
4aed14e3 | 485 | tp->t_timer[TCPT_REXMT] = 0; |
6703c41f | 486 | else { |
4aed14e3 BJ |
487 | TCPT_RANGESET(tp->t_timer[TCPT_REXMT], |
488 | tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); | |
dd020fc8 | 489 | tp->t_rtt = 1; |
22856bb8 | 490 | tp->t_rxtshift = 0; |
8a13b737 | 491 | } |
6703c41f BJ |
492 | if (acked > so->so_snd.sb_cc) { |
493 | sbdrop(&so->so_snd, so->so_snd.sb_cc); | |
494 | tp->snd_wnd -= so->so_snd.sb_cc; | |
495 | } else { | |
668cc26d | 496 | sbdrop(&so->so_snd, acked); |
6703c41f BJ |
497 | tp->snd_wnd -= acked; |
498 | acked = 0; | |
499 | } | |
5744ed2b | 500 | if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel) |
22856bb8 | 501 | sowwakeup(so); |
4b6b94ca | 502 | tp->snd_una = ti->ti_ack; |
b8977237 BJ |
503 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
504 | tp->snd_nxt = tp->snd_una; | |
405c9168 | 505 | |
87e78f19 BJ |
506 | switch (tp->t_state) { |
507 | ||
2ff61f9d BJ |
508 | /* |
509 | * In FIN_WAIT_1 STATE in addition to the processing | |
510 | * for the ESTABLISHED state if our FIN is now acknowledged | |
8a13b737 | 511 | * then enter FIN_WAIT_2. |
2ff61f9d BJ |
512 | */ |
513 | case TCPS_FIN_WAIT_1: | |
fdae4427 BJ |
514 | if (ourfinisacked) { |
515 | /* | |
516 | * If we can't receive any more | |
517 | * data, then closing user can proceed. | |
518 | */ | |
519 | if (so->so_state & SS_CANTRCVMORE) | |
520 | soisdisconnected(so); | |
8a13b737 | 521 | tp->t_state = TCPS_FIN_WAIT_2; |
fdae4427 | 522 | } |
87e78f19 BJ |
523 | break; |
524 | ||
2ff61f9d BJ |
525 | /* |
526 | * In CLOSING STATE in addition to the processing for | |
527 | * the ESTABLISHED state if the ACK acknowledges our FIN | |
528 | * then enter the TIME-WAIT state, otherwise ignore | |
529 | * the segment. | |
530 | */ | |
531 | case TCPS_CLOSING: | |
4aed14e3 | 532 | if (ourfinisacked) { |
2ff61f9d | 533 | tp->t_state = TCPS_TIME_WAIT; |
4aed14e3 BJ |
534 | tcp_canceltimers(tp); |
535 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; | |
536 | soisdisconnected(so); | |
537 | } | |
538 | break; | |
87e78f19 | 539 | |
2ff61f9d | 540 | /* |
8a13b737 BJ |
541 | * The only thing that can arrive in LAST_ACK state |
542 | * is an acknowledgment of our FIN. If our FIN is now | |
543 | * acknowledged, delete the TCB, enter the closed state | |
544 | * and return. | |
2ff61f9d BJ |
545 | */ |
546 | case TCPS_LAST_ACK: | |
93f92b1d | 547 | if (ourfinisacked) { |
2ff61f9d | 548 | tcp_close(tp); |
93f92b1d BJ |
549 | tp = 0; |
550 | } | |
2ff61f9d | 551 | goto drop; |
87e78f19 | 552 | |
2ff61f9d BJ |
553 | /* |
554 | * In TIME_WAIT state the only thing that should arrive | |
555 | * is a retransmission of the remote FIN. Acknowledge | |
556 | * it and restart the finack timer. | |
557 | */ | |
558 | case TCPS_TIME_WAIT: | |
405c9168 | 559 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 560 | goto dropafterack; |
87e78f19 | 561 | } |
8a13b737 BJ |
562 | #undef ourfinisacked |
563 | } | |
87e78f19 | 564 | |
2ff61f9d | 565 | step6: |
4aed14e3 BJ |
566 | /* |
567 | * Update window information. | |
568 | */ | |
22856bb8 | 569 | if (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && |
8e65fd66 | 570 | (SEQ_LT(tp->snd_wl2, ti->ti_ack) || |
22856bb8 | 571 | tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd)) { |
4aed14e3 BJ |
572 | tp->snd_wnd = ti->ti_win; |
573 | tp->snd_wl1 = ti->ti_seq; | |
574 | tp->snd_wl2 = ti->ti_ack; | |
a8d3bf7f | 575 | if (tp->snd_wnd != 0) |
4aed14e3 BJ |
576 | tp->t_timer[TCPT_PERSIST] = 0; |
577 | } | |
4aed14e3 | 578 | |
2ff61f9d | 579 | /* |
b2db9217 | 580 | * Process segments with URG. |
2ff61f9d | 581 | */ |
9c811062 BJ |
582 | if ((tiflags & TH_URG) && ti->ti_urp && |
583 | TCPS_HAVERCVDFIN(tp->t_state) == 0) { | |
b2db9217 BJ |
584 | /* |
585 | * If this segment advances the known urgent pointer, | |
586 | * then mark the data stream. This should not happen | |
587 | * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since | |
588 | * a FIN has been received from the remote side. | |
589 | * In these states we ignore the URG. | |
590 | */ | |
591 | if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { | |
592 | tp->rcv_up = ti->ti_seq + ti->ti_urp; | |
593 | so->so_oobmark = so->so_rcv.sb_cc + | |
594 | (tp->rcv_up - tp->rcv_nxt) - 1; | |
595 | if (so->so_oobmark == 0) | |
596 | so->so_state |= SS_RCVATMARK; | |
77a4e3ca | 597 | sohasoutofband(so); |
b2db9217 BJ |
598 | tp->t_oobflags &= ~TCPOOB_HAVEDATA; |
599 | } | |
600 | /* | |
601 | * Remove out of band data so doesn't get presented to user. | |
602 | * This can happen independent of advancing the URG pointer, | |
603 | * but if two URG's are pending at once, some out-of-band | |
604 | * data may creep in... ick. | |
605 | */ | |
ebf42a75 | 606 | if (ti->ti_urp <= ti->ti_len) |
b2db9217 | 607 | tcp_pulloutofband(so, ti); |
5e74df82 | 608 | } |
87e78f19 BJ |
609 | |
610 | /* | |
2ff61f9d BJ |
611 | * Process the segment text, merging it into the TCP sequencing queue, |
612 | * and arranging for acknowledgment of receipt if necessary. | |
613 | * This process logically involves adjusting tp->rcv_wnd as data | |
614 | * is presented to the user (this happens in tcp_usrreq.c, | |
615 | * case PRU_RCVD). If a FIN has already been received on this | |
616 | * connection then we just ignore the text. | |
87e78f19 | 617 | */ |
e832edbc BJ |
618 | if ((ti->ti_len || (tiflags&TH_FIN)) && |
619 | TCPS_HAVERCVDFIN(tp->t_state) == 0) { | |
2ff61f9d | 620 | tiflags = tcp_reass(tp, ti); |
8b5a83bb BJ |
621 | if (tcpnodelack == 0) |
622 | tp->t_flags |= TF_DELACK; | |
623 | else | |
624 | tp->t_flags |= TF_ACKNOW; | |
4aed14e3 | 625 | } else { |
2b4b57cd | 626 | m_freem(m); |
e832edbc | 627 | tiflags &= ~TH_FIN; |
4aed14e3 | 628 | } |
87e78f19 BJ |
629 | |
630 | /* | |
e832edbc BJ |
631 | * If FIN is received ACK the FIN and let the user know |
632 | * that the connection is closing. | |
87e78f19 | 633 | */ |
e832edbc | 634 | if (tiflags & TH_FIN) { |
4aed14e3 BJ |
635 | if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { |
636 | socantrcvmore(so); | |
637 | tp->t_flags |= TF_ACKNOW; | |
638 | tp->rcv_nxt++; | |
639 | } | |
2ff61f9d | 640 | switch (tp->t_state) { |
87e78f19 | 641 | |
2ff61f9d BJ |
642 | /* |
643 | * In SYN_RECEIVED and ESTABLISHED STATES | |
644 | * enter the CLOSE_WAIT state. | |
53a5409e | 645 | */ |
2ff61f9d BJ |
646 | case TCPS_SYN_RECEIVED: |
647 | case TCPS_ESTABLISHED: | |
648 | tp->t_state = TCPS_CLOSE_WAIT; | |
649 | break; | |
53a5409e | 650 | |
2ff61f9d | 651 | /* |
8a13b737 BJ |
652 | * If still in FIN_WAIT_1 STATE FIN has not been acked so |
653 | * enter the CLOSING state. | |
53a5409e | 654 | */ |
2ff61f9d | 655 | case TCPS_FIN_WAIT_1: |
8a13b737 | 656 | tp->t_state = TCPS_CLOSING; |
2ff61f9d | 657 | break; |
87e78f19 | 658 | |
2ff61f9d BJ |
659 | /* |
660 | * In FIN_WAIT_2 state enter the TIME_WAIT state, | |
661 | * starting the time-wait timer, turning off the other | |
662 | * standard timers. | |
663 | */ | |
664 | case TCPS_FIN_WAIT_2: | |
4aed14e3 | 665 | tp->t_state = TCPS_TIME_WAIT; |
a6503abf | 666 | tcp_canceltimers(tp); |
405c9168 | 667 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
4aed14e3 | 668 | soisdisconnected(so); |
2ff61f9d BJ |
669 | break; |
670 | ||
53a5409e | 671 | /* |
2ff61f9d | 672 | * In TIME_WAIT state restart the 2 MSL time_wait timer. |
53a5409e | 673 | */ |
2ff61f9d | 674 | case TCPS_TIME_WAIT: |
405c9168 | 675 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 676 | break; |
8a13b737 | 677 | } |
87e78f19 | 678 | } |
4b935108 BJ |
679 | if (so->so_options & SO_DEBUG) |
680 | tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); | |
8a13b737 BJ |
681 | |
682 | /* | |
683 | * Return any desired output. | |
684 | */ | |
668cc26d | 685 | (void) tcp_output(tp); |
2ff61f9d | 686 | return; |
8a13b737 | 687 | |
2ff61f9d | 688 | dropafterack: |
8a13b737 | 689 | /* |
1e977657 BJ |
690 | * Generate an ACK dropping incoming segment if it occupies |
691 | * sequence space, where the ACK reflects our state. | |
8a13b737 | 692 | */ |
1e977657 BJ |
693 | if ((tiflags&TH_RST) || |
694 | tlen == 0 && (tiflags&(TH_SYN|TH_FIN)) == 0) | |
8a13b737 | 695 | goto drop; |
f3cdd721 BJ |
696 | if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG) |
697 | tcp_trace(TA_RESPOND, ostate, tp, &tcp_saveti, 0); | |
8e65fd66 | 698 | tcp_respond(tp, ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK); |
4b6b94ca | 699 | return; |
8a13b737 BJ |
700 | |
701 | dropwithreset: | |
8b5a83bb | 702 | if (om) |
668cc26d | 703 | (void) m_free(om); |
8a13b737 | 704 | /* |
4aed14e3 | 705 | * Generate a RST, dropping incoming segment. |
8a13b737 BJ |
706 | * Make ACK acceptable to originator of segment. |
707 | */ | |
708 | if (tiflags & TH_RST) | |
709 | goto drop; | |
710 | if (tiflags & TH_ACK) | |
8e65fd66 | 711 | tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); |
8a13b737 BJ |
712 | else { |
713 | if (tiflags & TH_SYN) | |
714 | ti->ti_len++; | |
1e977657 BJ |
715 | tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, |
716 | TH_RST|TH_ACK); | |
8a13b737 | 717 | } |
4b6b94ca | 718 | return; |
8a13b737 | 719 | |
2ff61f9d | 720 | drop: |
8a13b737 BJ |
721 | /* |
722 | * Drop space held by incoming segment and return. | |
723 | */ | |
f3cdd721 BJ |
724 | if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) |
725 | tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); | |
2ff61f9d | 726 | m_freem(m); |
4b935108 | 727 | return; |
2ff61f9d BJ |
728 | } |
729 | ||
8b5a83bb BJ |
730 | tcp_dooptions(tp, om) |
731 | struct tcpcb *tp; | |
732 | struct mbuf *om; | |
5e74df82 | 733 | { |
8b5a83bb BJ |
734 | register u_char *cp; |
735 | int opt, optlen, cnt; | |
736 | ||
737 | cp = mtod(om, u_char *); | |
738 | cnt = om->m_len; | |
739 | for (; cnt > 0; cnt -= optlen, cp += optlen) { | |
740 | opt = cp[0]; | |
741 | if (opt == TCPOPT_EOL) | |
742 | break; | |
743 | if (opt == TCPOPT_NOP) | |
744 | optlen = 1; | |
745 | else | |
746 | optlen = cp[1]; | |
747 | switch (opt) { | |
748 | ||
749 | default: | |
750 | break; | |
751 | ||
752 | case TCPOPT_MAXSEG: | |
753 | if (optlen != 4) | |
754 | continue; | |
755 | tp->t_maxseg = *(u_short *)(cp + 2); | |
668cc26d | 756 | tp->t_maxseg = ntohs((u_short)tp->t_maxseg); |
8b5a83bb | 757 | break; |
8b5a83bb | 758 | } |
5e74df82 | 759 | } |
668cc26d | 760 | (void) m_free(om); |
5e74df82 BJ |
761 | } |
762 | ||
b2db9217 BJ |
763 | /* |
764 | * Pull out of band byte out of a segment so | |
765 | * it doesn't appear in the user's data queue. | |
766 | * It is still reflected in the segment length for | |
767 | * sequencing purposes. | |
768 | */ | |
769 | tcp_pulloutofband(so, ti) | |
770 | struct socket *so; | |
771 | struct tcpiphdr *ti; | |
772 | { | |
773 | register struct mbuf *m; | |
1acff8ec | 774 | int cnt = ti->ti_urp - 1; |
b2db9217 BJ |
775 | |
776 | m = dtom(ti); | |
777 | while (cnt >= 0) { | |
778 | if (m->m_len > cnt) { | |
779 | char *cp = mtod(m, caddr_t) + cnt; | |
780 | struct tcpcb *tp = sototcpcb(so); | |
781 | ||
782 | tp->t_iobc = *cp; | |
783 | tp->t_oobflags |= TCPOOB_HAVEDATA; | |
668cc26d | 784 | bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); |
b2db9217 BJ |
785 | m->m_len--; |
786 | return; | |
787 | } | |
788 | cnt -= m->m_len; | |
789 | m = m->m_next; | |
790 | if (m == 0) | |
791 | break; | |
792 | } | |
793 | panic("tcp_pulloutofband"); | |
794 | } | |
795 | ||
2ff61f9d BJ |
796 | /* |
797 | * Insert segment ti into reassembly queue of tcp with | |
798 | * control block tp. Return TH_FIN if reassembly now includes | |
799 | * a segment with FIN. | |
800 | */ | |
f1b2fa5b | 801 | tcp_reass(tp, ti) |
2ff61f9d BJ |
802 | register struct tcpcb *tp; |
803 | register struct tcpiphdr *ti; | |
2ff61f9d BJ |
804 | { |
805 | register struct tcpiphdr *q; | |
8a13b737 | 806 | struct socket *so = tp->t_inpcb->inp_socket; |
e832edbc BJ |
807 | struct mbuf *m; |
808 | int flags; | |
2ff61f9d BJ |
809 | |
810 | /* | |
405c9168 BJ |
811 | * Call with ti==0 after become established to |
812 | * force pre-ESTABLISHED data up to user socket. | |
2ff61f9d | 813 | */ |
405c9168 | 814 | if (ti == 0) |
2ff61f9d | 815 | goto present; |
87e78f19 | 816 | |
2ff61f9d BJ |
817 | /* |
818 | * Find a segment which begins after this one does. | |
819 | */ | |
820 | for (q = tp->seg_next; q != (struct tcpiphdr *)tp; | |
821 | q = (struct tcpiphdr *)q->ti_next) | |
822 | if (SEQ_GT(q->ti_seq, ti->ti_seq)) | |
823 | break; | |
824 | ||
825 | /* | |
826 | * If there is a preceding segment, it may provide some of | |
827 | * our data already. If so, drop the data from the incoming | |
828 | * segment. If it provides all of our data, drop us. | |
829 | */ | |
830 | if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { | |
831 | register int i; | |
fd5dc5f0 | 832 | q = (struct tcpiphdr *)q->ti_prev; |
2ff61f9d BJ |
833 | /* conversion to int (in i) handles seq wraparound */ |
834 | i = q->ti_seq + q->ti_len - ti->ti_seq; | |
835 | if (i > 0) { | |
2b4b57cd | 836 | if (i >= ti->ti_len) |
2ff61f9d | 837 | goto drop; |
4ab1a5c3 | 838 | m_adj(dtom(ti), i); |
2b4b57cd | 839 | ti->ti_len -= i; |
2ff61f9d | 840 | ti->ti_seq += i; |
53a5409e | 841 | } |
2ff61f9d BJ |
842 | q = (struct tcpiphdr *)(q->ti_next); |
843 | } | |
87e78f19 | 844 | |
2ff61f9d BJ |
845 | /* |
846 | * While we overlap succeeding segments trim them or, | |
847 | * if they are completely covered, dequeue them. | |
848 | */ | |
fd5dc5f0 | 849 | while (q != (struct tcpiphdr *)tp) { |
2ff61f9d | 850 | register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; |
fd5dc5f0 BJ |
851 | if (i <= 0) |
852 | break; | |
2ff61f9d | 853 | if (i < q->ti_len) { |
fd5dc5f0 | 854 | q->ti_seq += i; |
2ff61f9d BJ |
855 | q->ti_len -= i; |
856 | m_adj(dtom(q), i); | |
857 | break; | |
ac5e71a1 | 858 | } |
2ff61f9d | 859 | q = (struct tcpiphdr *)q->ti_next; |
473a17a5 | 860 | m = dtom(q->ti_prev); |
2ff61f9d | 861 | remque(q->ti_prev); |
473a17a5 | 862 | m_freem(m); |
2ff61f9d | 863 | } |
87e78f19 | 864 | |
2ff61f9d BJ |
865 | /* |
866 | * Stick new segment in its place. | |
867 | */ | |
868 | insque(ti, q->ti_prev); | |
2ff61f9d | 869 | |
2ff61f9d BJ |
870 | present: |
871 | /* | |
4aed14e3 BJ |
872 | * Present data to user, advancing rcv_nxt through |
873 | * completed sequence space. | |
2ff61f9d | 874 | */ |
e832edbc | 875 | if (TCPS_HAVERCVDSYN(tp->t_state) == 0) |
4aed14e3 | 876 | return (0); |
2b4b57cd | 877 | ti = tp->seg_next; |
e832edbc BJ |
878 | if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) |
879 | return (0); | |
880 | if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) | |
881 | return (0); | |
882 | do { | |
4aed14e3 BJ |
883 | tp->rcv_nxt += ti->ti_len; |
884 | flags = ti->ti_flags & TH_FIN; | |
2b4b57cd | 885 | remque(ti); |
e832edbc | 886 | m = dtom(ti); |
2b4b57cd | 887 | ti = (struct tcpiphdr *)ti->ti_next; |
e832edbc | 888 | if (so->so_state & SS_CANTRCVMORE) |
668cc26d | 889 | m_freem(m); |
789d2a39 | 890 | else |
e832edbc BJ |
891 | sbappend(&so->so_rcv, m); |
892 | } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); | |
893 | sorwakeup(so); | |
2ff61f9d BJ |
894 | return (flags); |
895 | drop: | |
896 | m_freem(dtom(ti)); | |
e832edbc | 897 | return (0); |
d52566dd | 898 | } |