Commit | Line | Data |
---|---|---|
27d029ad | 1 | /* tcp_input.c 1.90 83/03/25 */ |
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" |
f4d55810 SL |
9 | #include "../h/errno.h" |
10 | ||
11 | #include "../net/if.h" | |
c124e997 | 12 | #include "../net/route.h" |
f4d55810 SL |
13 | |
14 | #include "../netinet/in.h" | |
fcfe450e BJ |
15 | #include "../netinet/in_pcb.h" |
16 | #include "../netinet/in_systm.h" | |
fcfe450e BJ |
17 | #include "../netinet/ip.h" |
18 | #include "../netinet/ip_var.h" | |
19 | #include "../netinet/tcp.h" | |
20 | #include "../netinet/tcp_fsm.h" | |
21 | #include "../netinet/tcp_seq.h" | |
22 | #include "../netinet/tcp_timer.h" | |
23 | #include "../netinet/tcp_var.h" | |
24 | #include "../netinet/tcpip.h" | |
25 | #include "../netinet/tcp_debug.h" | |
87e78f19 | 26 | |
22856bb8 | 27 | int tcpprintfs = 0; |
60b16fa9 | 28 | int tcpcksum = 1; |
4b935108 | 29 | struct tcpiphdr tcp_saveti; |
8b5a83bb | 30 | extern tcpnodelack; |
87e78f19 | 31 | |
4b935108 | 32 | struct tcpcb *tcp_newtcpcb(); |
2ff61f9d BJ |
33 | /* |
34 | * TCP input routine, follows pages 65-76 of the | |
35 | * protocol specification dated September, 1981 very closely. | |
36 | */ | |
2b4b57cd BJ |
37 | tcp_input(m0) |
38 | struct mbuf *m0; | |
87e78f19 | 39 | { |
2b4b57cd | 40 | register struct tcpiphdr *ti; |
53a5409e | 41 | struct inpcb *inp; |
2b4b57cd | 42 | register struct mbuf *m; |
8b5a83bb | 43 | struct mbuf *om = 0; |
2b4b57cd | 44 | int len, tlen, off; |
8e65fd66 | 45 | register struct tcpcb *tp = 0; |
2b4b57cd | 46 | register int tiflags; |
d52566dd | 47 | struct socket *so; |
f1b2fa5b | 48 | int todrop, acked; |
4b935108 | 49 | short ostate; |
ebcadd38 | 50 | struct in_addr laddr; |
7aa16f99 | 51 | int dropsocket = 0; |
87e78f19 BJ |
52 | |
53 | /* | |
4aed14e3 BJ |
54 | * Get IP and TCP header together in first mbuf. |
55 | * Note: IP leaves IP header in first mbuf. | |
87e78f19 | 56 | */ |
2b4b57cd | 57 | m = m0; |
20790db4 | 58 | ti = mtod(m, struct tcpiphdr *); |
4aed14e3 | 59 | if (((struct ip *)ti)->ip_hl > (sizeof (struct ip) >> 2)) |
d63599ac | 60 | ip_stripoptions((struct ip *)ti, (struct mbuf *)0); |
6703c41f BJ |
61 | if (m->m_off > MMAXOFF || m->m_len < sizeof (struct tcpiphdr)) { |
62 | if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) { | |
8a13b737 | 63 | tcpstat.tcps_hdrops++; |
6703c41f | 64 | return; |
8a13b737 BJ |
65 | } |
66 | ti = mtod(m, struct tcpiphdr *); | |
67 | } | |
87e78f19 | 68 | |
2b4b57cd | 69 | /* |
4aed14e3 | 70 | * Checksum extended TCP header and data. |
2b4b57cd BJ |
71 | */ |
72 | tlen = ((struct ip *)ti)->ip_len; | |
73 | len = sizeof (struct ip) + tlen; | |
60b16fa9 | 74 | if (tcpcksum) { |
2b4b57cd BJ |
75 | ti->ti_next = ti->ti_prev = 0; |
76 | ti->ti_x1 = 0; | |
ac83b17a | 77 | ti->ti_len = (u_short)tlen; |
668cc26d | 78 | ti->ti_len = htons((u_short)ti->ti_len); |
4b6b94ca | 79 | if (ti->ti_sum = in_cksum(m, len)) { |
2b4b57cd | 80 | tcpstat.tcps_badsum++; |
1e977657 BJ |
81 | if (tcpprintfs) |
82 | printf("tcp cksum %x\n", ti->ti_sum); | |
8a13b737 | 83 | goto drop; |
87e78f19 BJ |
84 | } |
85 | } | |
86 | ||
87 | /* | |
4aed14e3 | 88 | * Check that TCP offset makes sense, |
8b5a83bb | 89 | * pull out TCP options and adjust length. |
87e78f19 | 90 | */ |
2b4b57cd | 91 | off = ti->ti_off << 2; |
4b6b94ca | 92 | if (off < sizeof (struct tcphdr) || off > tlen) { |
2b4b57cd | 93 | tcpstat.tcps_badoff++; |
8a13b737 | 94 | goto drop; |
2b4b57cd | 95 | } |
1e977657 BJ |
96 | tlen -= off; |
97 | ti->ti_len = tlen; | |
8b5a83bb BJ |
98 | if (off > sizeof (struct tcphdr)) { |
99 | if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) { | |
100 | tcpstat.tcps_hdrops++; | |
101 | goto drop; | |
102 | } | |
103 | ti = mtod(m, struct tcpiphdr *); | |
cce93e4b | 104 | om = m_get(M_DONTWAIT, MT_DATA); |
8b5a83bb BJ |
105 | if (om == 0) |
106 | goto drop; | |
8b5a83bb BJ |
107 | om->m_len = off - sizeof (struct tcphdr); |
108 | { caddr_t op = mtod(m, caddr_t) + sizeof (struct tcpiphdr); | |
668cc26d | 109 | bcopy(op, mtod(om, caddr_t), (unsigned)om->m_len); |
8b5a83bb | 110 | m->m_len -= om->m_len; |
668cc26d SL |
111 | bcopy(op+om->m_len, op, |
112 | (unsigned)(m->m_len-sizeof (struct tcpiphdr))); | |
8b5a83bb BJ |
113 | } |
114 | } | |
2ff61f9d | 115 | tiflags = ti->ti_flags; |
2b4b57cd | 116 | |
795e0416 | 117 | /* |
1e977657 | 118 | * Drop TCP and IP headers. |
795e0416 BJ |
119 | */ |
120 | off += sizeof (struct ip); | |
121 | m->m_off += off; | |
122 | m->m_len -= off; | |
123 | ||
8a13b737 | 124 | /* |
4aed14e3 | 125 | * Convert TCP protocol specific fields to host format. |
8a13b737 BJ |
126 | */ |
127 | ti->ti_seq = ntohl(ti->ti_seq); | |
128 | ti->ti_ack = ntohl(ti->ti_ack); | |
129 | ti->ti_win = ntohs(ti->ti_win); | |
130 | ti->ti_urp = ntohs(ti->ti_urp); | |
131 | ||
2b4b57cd | 132 | /* |
8075bb0e | 133 | * Locate pcb for segment. |
2b4b57cd | 134 | */ |
2ff61f9d | 135 | inp = in_pcblookup |
ebcadd38 BJ |
136 | (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport, |
137 | INPLOOKUP_WILDCARD); | |
2ff61f9d BJ |
138 | |
139 | /* | |
140 | * If the state is CLOSED (i.e., TCB does not exist) then | |
4aed14e3 | 141 | * all data in the incoming segment is discarded. |
2ff61f9d | 142 | */ |
22856bb8 | 143 | if (inp == 0) |
8a13b737 | 144 | goto dropwithreset; |
2ff61f9d | 145 | tp = intotcpcb(inp); |
22856bb8 | 146 | if (tp == 0) |
8a13b737 | 147 | goto dropwithreset; |
f1b2fa5b | 148 | so = inp->inp_socket; |
4b935108 BJ |
149 | if (so->so_options & SO_DEBUG) { |
150 | ostate = tp->t_state; | |
151 | tcp_saveti = *ti; | |
152 | } | |
ebf42a75 BJ |
153 | if (so->so_options & SO_ACCEPTCONN) { |
154 | so = sonewconn(so); | |
155 | if (so == 0) | |
156 | goto drop; | |
7aa16f99 SL |
157 | /* |
158 | * This is ugly, but .... | |
159 | * | |
160 | * Mark socket as temporary until we're | |
161 | * committed to keeping it. The code at | |
162 | * ``drop'' and ``dropwithreset'' check the | |
163 | * flag dropsocket to see if the temporary | |
164 | * socket created here should be discarded. | |
165 | * We mark the socket as discardable until | |
166 | * we're committed to it below in TCPS_LISTEN. | |
167 | */ | |
168 | dropsocket++; | |
ebf42a75 BJ |
169 | inp = (struct inpcb *)so->so_pcb; |
170 | inp->inp_laddr = ti->ti_dst; | |
171 | inp->inp_lport = ti->ti_dport; | |
172 | tp = intotcpcb(inp); | |
173 | tp->t_state = TCPS_LISTEN; | |
174 | } | |
87e78f19 | 175 | |
405c9168 BJ |
176 | /* |
177 | * Segment received on connection. | |
178 | * Reset idle time and keep-alive timer. | |
179 | */ | |
180 | tp->t_idle = 0; | |
181 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; | |
182 | ||
8b5a83bb BJ |
183 | /* |
184 | * Process options. | |
185 | */ | |
186 | if (om) { | |
187 | tcp_dooptions(tp, om); | |
188 | om = 0; | |
189 | } | |
190 | ||
87e78f19 | 191 | /* |
8a13b737 BJ |
192 | * Calculate amount of space in receive window, |
193 | * and then do TCP input processing. | |
87e78f19 | 194 | */ |
8a13b737 | 195 | tp->rcv_wnd = sbspace(&so->so_rcv); |
4b6b94ca BJ |
196 | if (tp->rcv_wnd < 0) |
197 | tp->rcv_wnd = 0; | |
2ff61f9d | 198 | |
87e78f19 BJ |
199 | switch (tp->t_state) { |
200 | ||
2ff61f9d BJ |
201 | /* |
202 | * If the state is LISTEN then ignore segment if it contains an RST. | |
203 | * If the segment contains an ACK then it is bad and send a RST. | |
204 | * If it does not contain a SYN then it is not interesting; drop it. | |
8a13b737 | 205 | * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial |
2ff61f9d | 206 | * tp->iss, and send a segment: |
8a13b737 | 207 | * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> |
2ff61f9d BJ |
208 | * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. |
209 | * Fill in remote peer address fields if not previously specified. | |
210 | * Enter SYN_RECEIVED state, and process any other fields of this | |
4aed14e3 | 211 | * segment in this state. |
2ff61f9d | 212 | */ |
8075bb0e | 213 | case TCPS_LISTEN: { |
789d2a39 | 214 | struct mbuf *am; |
8075bb0e BJ |
215 | register struct sockaddr_in *sin; |
216 | ||
2ff61f9d BJ |
217 | if (tiflags & TH_RST) |
218 | goto drop; | |
22856bb8 | 219 | if (tiflags & TH_ACK) |
8a13b737 | 220 | goto dropwithreset; |
22856bb8 | 221 | if ((tiflags & TH_SYN) == 0) |
2ff61f9d | 222 | goto drop; |
789d2a39 SL |
223 | am = m_get(M_DONTWAIT, MT_SONAME); |
224 | if (am == NULL) | |
225 | goto drop; | |
226 | am->m_len = sizeof (struct sockaddr_in); | |
a8d3bf7f | 227 | sin = mtod(am, struct sockaddr_in *); |
8075bb0e BJ |
228 | sin->sin_family = AF_INET; |
229 | sin->sin_addr = ti->ti_src; | |
230 | sin->sin_port = ti->ti_sport; | |
ebcadd38 | 231 | laddr = inp->inp_laddr; |
789d2a39 | 232 | if (inp->inp_laddr.s_addr == INADDR_ANY) |
ebcadd38 | 233 | inp->inp_laddr = ti->ti_dst; |
a8d3bf7f | 234 | if (in_pcbconnect(inp, am)) { |
ebcadd38 | 235 | inp->inp_laddr = laddr; |
5a1f132a | 236 | (void) m_free(am); |
4aed14e3 | 237 | goto drop; |
ebcadd38 | 238 | } |
5a1f132a | 239 | (void) m_free(am); |
4aed14e3 BJ |
240 | tp->t_template = tcp_template(tp); |
241 | if (tp->t_template == 0) { | |
242 | in_pcbdisconnect(inp); | |
ebcadd38 | 243 | inp->inp_laddr = laddr; |
93f92b1d | 244 | tp = 0; |
4aed14e3 BJ |
245 | goto drop; |
246 | } | |
8a13b737 | 247 | tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; |
2ff61f9d | 248 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
249 | tcp_sendseqinit(tp); |
250 | tcp_rcvseqinit(tp); | |
2ff61f9d | 251 | tp->t_state = TCPS_SYN_RECEIVED; |
4aed14e3 | 252 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; |
7aa16f99 | 253 | dropsocket = 0; /* committed to socket */ |
8a13b737 | 254 | goto trimthenstep6; |
8075bb0e | 255 | } |
87e78f19 | 256 | |
2ff61f9d BJ |
257 | /* |
258 | * If the state is SYN_SENT: | |
259 | * if seg contains an ACK, but not for our SYN, drop the input. | |
260 | * if seg contains a RST, then drop the connection. | |
261 | * if seg does not contain SYN, then drop it. | |
262 | * Otherwise this is an acceptable SYN segment | |
263 | * initialize tp->rcv_nxt and tp->irs | |
264 | * if seg contains ack then advance tp->snd_una | |
265 | * if SYN has been acked change to ESTABLISHED else SYN_RCVD state | |
266 | * arrange for segment to be acked (eventually) | |
267 | * continue processing rest of data/controls, beginning with URG | |
268 | */ | |
269 | case TCPS_SYN_SENT: | |
270 | if ((tiflags & TH_ACK) && | |
22856bb8 BJ |
271 | /* this should be SEQ_LT; is SEQ_LEQ for BBN vax TCP only */ |
272 | (SEQ_LT(ti->ti_ack, tp->iss) || | |
4b6b94ca | 273 | SEQ_GT(ti->ti_ack, tp->snd_max))) |
8a13b737 | 274 | goto dropwithreset; |
2ff61f9d | 275 | if (tiflags & TH_RST) { |
0e3936fa SL |
276 | if (tiflags & TH_ACK) |
277 | tp = tcp_drop(tp, ECONNREFUSED); | |
2ff61f9d | 278 | goto drop; |
87e78f19 | 279 | } |
2ff61f9d BJ |
280 | if ((tiflags & TH_SYN) == 0) |
281 | goto drop; | |
4b6b94ca | 282 | tp->snd_una = ti->ti_ack; |
b8977237 BJ |
283 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
284 | tp->snd_nxt = tp->snd_una; | |
4aed14e3 | 285 | tp->t_timer[TCPT_REXMT] = 0; |
2ff61f9d | 286 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
287 | tcp_rcvseqinit(tp); |
288 | tp->t_flags |= TF_ACKNOW; | |
405c9168 | 289 | if (SEQ_GT(tp->snd_una, tp->iss)) { |
4aed14e3 | 290 | soisconnected(so); |
2ff61f9d | 291 | tp->t_state = TCPS_ESTABLISHED; |
405c9168 BJ |
292 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
293 | } else | |
8a13b737 BJ |
294 | tp->t_state = TCPS_SYN_RECEIVED; |
295 | goto trimthenstep6; | |
296 | ||
297 | trimthenstep6: | |
298 | /* | |
4b6b94ca | 299 | * Advance ti->ti_seq to correspond to first data byte. |
8a13b737 BJ |
300 | * If data, trim to stay within window, |
301 | * dropping FIN if necessary. | |
302 | */ | |
4b6b94ca | 303 | ti->ti_seq++; |
8a13b737 BJ |
304 | if (ti->ti_len > tp->rcv_wnd) { |
305 | todrop = ti->ti_len - tp->rcv_wnd; | |
306 | m_adj(m, -todrop); | |
307 | ti->ti_len = tp->rcv_wnd; | |
308 | ti->ti_flags &= ~TH_FIN; | |
87e78f19 | 309 | } |
e832edbc | 310 | tp->snd_wl1 = ti->ti_seq - 1; |
8a13b737 | 311 | goto step6; |
2ff61f9d | 312 | } |
87e78f19 | 313 | |
2ff61f9d BJ |
314 | /* |
315 | * States other than LISTEN or SYN_SENT. | |
316 | * First check that at least some bytes of segment are within | |
317 | * receive window. | |
318 | */ | |
319 | if (tp->rcv_wnd == 0) { | |
320 | /* | |
321 | * If window is closed can only take segments at | |
4b6b94ca | 322 | * window edge, and have to drop data and PUSH from |
2ff61f9d BJ |
323 | * incoming segments. |
324 | */ | |
22856bb8 | 325 | if (tp->rcv_nxt != ti->ti_seq) |
2ff61f9d | 326 | goto dropafterack; |
8a13b737 | 327 | if (ti->ti_len > 0) { |
fd5dc5f0 | 328 | m_adj(m, ti->ti_len); |
8a13b737 BJ |
329 | ti->ti_len = 0; |
330 | ti->ti_flags &= ~(TH_PUSH|TH_FIN); | |
87e78f19 | 331 | } |
2ff61f9d BJ |
332 | } else { |
333 | /* | |
4b6b94ca | 334 | * If segment begins before rcv_nxt, drop leading |
2ff61f9d BJ |
335 | * data (and SYN); if nothing left, just ack. |
336 | */ | |
fd5dc5f0 BJ |
337 | todrop = tp->rcv_nxt - ti->ti_seq; |
338 | if (todrop > 0) { | |
8a13b737 | 339 | if (tiflags & TH_SYN) { |
22856bb8 | 340 | tiflags &= ~TH_SYN; |
fd5dc5f0 | 341 | ti->ti_flags &= ~TH_SYN; |
8a13b737 BJ |
342 | ti->ti_seq++; |
343 | if (ti->ti_urp > 1) | |
344 | ti->ti_urp--; | |
345 | else | |
346 | tiflags &= ~TH_URG; | |
347 | todrop--; | |
348 | } | |
1e977657 BJ |
349 | if (todrop > ti->ti_len || |
350 | todrop == ti->ti_len && (tiflags&TH_FIN) == 0) | |
2ff61f9d BJ |
351 | goto dropafterack; |
352 | m_adj(m, todrop); | |
353 | ti->ti_seq += todrop; | |
354 | ti->ti_len -= todrop; | |
8a13b737 BJ |
355 | if (ti->ti_urp > todrop) |
356 | ti->ti_urp -= todrop; | |
357 | else { | |
358 | tiflags &= ~TH_URG; | |
fd5dc5f0 BJ |
359 | ti->ti_flags &= ~TH_URG; |
360 | ti->ti_urp = 0; | |
8a13b737 | 361 | } |
2ff61f9d BJ |
362 | } |
363 | /* | |
364 | * If segment ends after window, drop trailing data | |
8a13b737 | 365 | * (and PUSH and FIN); if nothing left, just ACK. |
2ff61f9d | 366 | */ |
fd5dc5f0 BJ |
367 | todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); |
368 | if (todrop > 0) { | |
1e977657 | 369 | if (todrop >= ti->ti_len) |
2ff61f9d BJ |
370 | goto dropafterack; |
371 | m_adj(m, -todrop); | |
372 | ti->ti_len -= todrop; | |
8a13b737 | 373 | ti->ti_flags &= ~(TH_PUSH|TH_FIN); |
87e78f19 | 374 | } |
87e78f19 | 375 | } |
87e78f19 | 376 | |
dd020fc8 | 377 | /* |
6fed2989 | 378 | * If data is received on a connection after the |
dd020fc8 BJ |
379 | * user processes are gone, then RST the other end. |
380 | */ | |
0e3936fa | 381 | if ((so->so_state & SS_NOFDREF) && tp->t_state > TCPS_CLOSE_WAIT && |
c9f1e449 | 382 | ti->ti_len) { |
0e3936fa | 383 | tp = tcp_close(tp); |
dd020fc8 BJ |
384 | goto dropwithreset; |
385 | } | |
386 | ||
87e78f19 | 387 | /* |
2ff61f9d BJ |
388 | * If the RST bit is set examine the state: |
389 | * SYN_RECEIVED STATE: | |
390 | * If passive open, return to LISTEN state. | |
391 | * If active open, inform user that connection was refused. | |
392 | * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: | |
393 | * Inform user that connection was reset, and close tcb. | |
394 | * CLOSING, LAST_ACK, TIME_WAIT STATES | |
395 | * Close the tcb. | |
87e78f19 | 396 | */ |
2ff61f9d | 397 | if (tiflags&TH_RST) switch (tp->t_state) { |
4b935108 | 398 | |
2ff61f9d | 399 | case TCPS_SYN_RECEIVED: |
0e3936fa | 400 | tp = tcp_drop(tp, ECONNREFUSED); |
2ff61f9d BJ |
401 | goto drop; |
402 | ||
403 | case TCPS_ESTABLISHED: | |
404 | case TCPS_FIN_WAIT_1: | |
405 | case TCPS_FIN_WAIT_2: | |
406 | case TCPS_CLOSE_WAIT: | |
0e3936fa | 407 | tp = tcp_drop(tp, ECONNRESET); |
2ff61f9d BJ |
408 | goto drop; |
409 | ||
410 | case TCPS_CLOSING: | |
411 | case TCPS_LAST_ACK: | |
412 | case TCPS_TIME_WAIT: | |
0e3936fa | 413 | tp = tcp_close(tp); |
2ff61f9d | 414 | goto drop; |
87e78f19 | 415 | } |
87e78f19 BJ |
416 | |
417 | /* | |
2ff61f9d BJ |
418 | * If a SYN is in the window, then this is an |
419 | * error and we send an RST and drop the connection. | |
420 | */ | |
421 | if (tiflags & TH_SYN) { | |
0e3936fa | 422 | tp = tcp_drop(tp, ECONNRESET); |
8a13b737 | 423 | goto dropwithreset; |
2ff61f9d BJ |
424 | } |
425 | ||
426 | /* | |
427 | * If the ACK bit is off we drop the segment and return. | |
428 | */ | |
8a13b737 | 429 | if ((tiflags & TH_ACK) == 0) |
2ff61f9d BJ |
430 | goto drop; |
431 | ||
432 | /* | |
433 | * Ack processing. | |
87e78f19 | 434 | */ |
87e78f19 BJ |
435 | switch (tp->t_state) { |
436 | ||
2ff61f9d BJ |
437 | /* |
438 | * In SYN_RECEIVED state if the ack ACKs our SYN then enter | |
439 | * ESTABLISHED state and continue processing, othewise | |
440 | * send an RST. | |
441 | */ | |
442 | case TCPS_SYN_RECEIVED: | |
8a13b737 | 443 | if (SEQ_GT(tp->snd_una, ti->ti_ack) || |
4b6b94ca | 444 | SEQ_GT(ti->ti_ack, tp->snd_max)) |
8a13b737 | 445 | goto dropwithreset; |
4aed14e3 | 446 | tp->snd_una++; /* SYN acked */ |
b8977237 BJ |
447 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
448 | tp->snd_nxt = tp->snd_una; | |
4aed14e3 | 449 | tp->t_timer[TCPT_REXMT] = 0; |
8a13b737 BJ |
450 | soisconnected(so); |
451 | tp->t_state = TCPS_ESTABLISHED; | |
405c9168 | 452 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
4aed14e3 | 453 | tp->snd_wl1 = ti->ti_seq - 1; |
8a13b737 | 454 | /* fall into ... */ |
87e78f19 | 455 | |
2ff61f9d BJ |
456 | /* |
457 | * In ESTABLISHED state: drop duplicate ACKs; ACK out of range | |
458 | * ACKs. If the ack is in the range | |
4b6b94ca | 459 | * tp->snd_una < ti->ti_ack <= tp->snd_max |
2ff61f9d BJ |
460 | * then advance tp->snd_una to ti->ti_ack and drop |
461 | * data from the retransmission queue. If this ACK reflects | |
462 | * more up to date window information we update our window information. | |
463 | */ | |
464 | case TCPS_ESTABLISHED: | |
465 | case TCPS_FIN_WAIT_1: | |
466 | case TCPS_FIN_WAIT_2: | |
467 | case TCPS_CLOSE_WAIT: | |
468 | case TCPS_CLOSING: | |
4aed14e3 BJ |
469 | case TCPS_LAST_ACK: |
470 | case TCPS_TIME_WAIT: | |
8a13b737 BJ |
471 | #define ourfinisacked (acked > 0) |
472 | ||
4aed14e3 | 473 | if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) |
2ff61f9d | 474 | break; |
22856bb8 | 475 | if (SEQ_GT(ti->ti_ack, tp->snd_max)) |
2ff61f9d | 476 | goto dropafterack; |
8a13b737 | 477 | acked = ti->ti_ack - tp->snd_una; |
dd020fc8 BJ |
478 | |
479 | /* | |
480 | * If transmit timer is running and timed sequence | |
481 | * number was acked, update smoothed round trip time. | |
482 | */ | |
483 | if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { | |
484 | if (tp->t_srtt == 0) | |
485 | tp->t_srtt = tp->t_rtt; | |
486 | else | |
487 | tp->t_srtt = | |
488 | tcp_alpha * tp->t_srtt + | |
489 | (1 - tcp_alpha) * tp->t_rtt; | |
dd020fc8 BJ |
490 | tp->t_rtt = 0; |
491 | } | |
492 | ||
6703c41f | 493 | if (ti->ti_ack == tp->snd_max) |
4aed14e3 | 494 | tp->t_timer[TCPT_REXMT] = 0; |
6703c41f | 495 | else { |
4aed14e3 BJ |
496 | TCPT_RANGESET(tp->t_timer[TCPT_REXMT], |
497 | tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); | |
dd020fc8 | 498 | tp->t_rtt = 1; |
22856bb8 | 499 | tp->t_rxtshift = 0; |
8a13b737 | 500 | } |
6703c41f BJ |
501 | if (acked > so->so_snd.sb_cc) { |
502 | sbdrop(&so->so_snd, so->so_snd.sb_cc); | |
503 | tp->snd_wnd -= so->so_snd.sb_cc; | |
504 | } else { | |
668cc26d | 505 | sbdrop(&so->so_snd, acked); |
6703c41f BJ |
506 | tp->snd_wnd -= acked; |
507 | acked = 0; | |
508 | } | |
5744ed2b | 509 | if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel) |
22856bb8 | 510 | sowwakeup(so); |
4b6b94ca | 511 | tp->snd_una = ti->ti_ack; |
b8977237 BJ |
512 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
513 | tp->snd_nxt = tp->snd_una; | |
405c9168 | 514 | |
87e78f19 BJ |
515 | switch (tp->t_state) { |
516 | ||
2ff61f9d BJ |
517 | /* |
518 | * In FIN_WAIT_1 STATE in addition to the processing | |
519 | * for the ESTABLISHED state if our FIN is now acknowledged | |
8a13b737 | 520 | * then enter FIN_WAIT_2. |
2ff61f9d BJ |
521 | */ |
522 | case TCPS_FIN_WAIT_1: | |
fdae4427 BJ |
523 | if (ourfinisacked) { |
524 | /* | |
525 | * If we can't receive any more | |
526 | * data, then closing user can proceed. | |
527 | */ | |
528 | if (so->so_state & SS_CANTRCVMORE) | |
529 | soisdisconnected(so); | |
8a13b737 | 530 | tp->t_state = TCPS_FIN_WAIT_2; |
fdae4427 | 531 | } |
87e78f19 BJ |
532 | break; |
533 | ||
2ff61f9d BJ |
534 | /* |
535 | * In CLOSING STATE in addition to the processing for | |
536 | * the ESTABLISHED state if the ACK acknowledges our FIN | |
537 | * then enter the TIME-WAIT state, otherwise ignore | |
538 | * the segment. | |
539 | */ | |
540 | case TCPS_CLOSING: | |
4aed14e3 | 541 | if (ourfinisacked) { |
2ff61f9d | 542 | tp->t_state = TCPS_TIME_WAIT; |
4aed14e3 BJ |
543 | tcp_canceltimers(tp); |
544 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; | |
545 | soisdisconnected(so); | |
546 | } | |
547 | break; | |
87e78f19 | 548 | |
2ff61f9d | 549 | /* |
8a13b737 BJ |
550 | * The only thing that can arrive in LAST_ACK state |
551 | * is an acknowledgment of our FIN. If our FIN is now | |
552 | * acknowledged, delete the TCB, enter the closed state | |
553 | * and return. | |
2ff61f9d BJ |
554 | */ |
555 | case TCPS_LAST_ACK: | |
0e3936fa SL |
556 | if (ourfinisacked) |
557 | tp = tcp_close(tp); | |
2ff61f9d | 558 | goto drop; |
87e78f19 | 559 | |
2ff61f9d BJ |
560 | /* |
561 | * In TIME_WAIT state the only thing that should arrive | |
562 | * is a retransmission of the remote FIN. Acknowledge | |
563 | * it and restart the finack timer. | |
564 | */ | |
565 | case TCPS_TIME_WAIT: | |
405c9168 | 566 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 567 | goto dropafterack; |
87e78f19 | 568 | } |
8a13b737 BJ |
569 | #undef ourfinisacked |
570 | } | |
87e78f19 | 571 | |
2ff61f9d | 572 | step6: |
4aed14e3 BJ |
573 | /* |
574 | * Update window information. | |
575 | */ | |
22856bb8 | 576 | if (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && |
8e65fd66 | 577 | (SEQ_LT(tp->snd_wl2, ti->ti_ack) || |
22856bb8 | 578 | tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd)) { |
4aed14e3 BJ |
579 | tp->snd_wnd = ti->ti_win; |
580 | tp->snd_wl1 = ti->ti_seq; | |
581 | tp->snd_wl2 = ti->ti_ack; | |
a8d3bf7f | 582 | if (tp->snd_wnd != 0) |
4aed14e3 BJ |
583 | tp->t_timer[TCPT_PERSIST] = 0; |
584 | } | |
4aed14e3 | 585 | |
2ff61f9d | 586 | /* |
b2db9217 | 587 | * Process segments with URG. |
2ff61f9d | 588 | */ |
9c811062 BJ |
589 | if ((tiflags & TH_URG) && ti->ti_urp && |
590 | TCPS_HAVERCVDFIN(tp->t_state) == 0) { | |
b2db9217 BJ |
591 | /* |
592 | * If this segment advances the known urgent pointer, | |
593 | * then mark the data stream. This should not happen | |
594 | * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since | |
595 | * a FIN has been received from the remote side. | |
596 | * In these states we ignore the URG. | |
597 | */ | |
598 | if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { | |
599 | tp->rcv_up = ti->ti_seq + ti->ti_urp; | |
600 | so->so_oobmark = so->so_rcv.sb_cc + | |
601 | (tp->rcv_up - tp->rcv_nxt) - 1; | |
602 | if (so->so_oobmark == 0) | |
603 | so->so_state |= SS_RCVATMARK; | |
77a4e3ca | 604 | sohasoutofband(so); |
b2db9217 BJ |
605 | tp->t_oobflags &= ~TCPOOB_HAVEDATA; |
606 | } | |
607 | /* | |
608 | * Remove out of band data so doesn't get presented to user. | |
609 | * This can happen independent of advancing the URG pointer, | |
610 | * but if two URG's are pending at once, some out-of-band | |
611 | * data may creep in... ick. | |
612 | */ | |
ebf42a75 | 613 | if (ti->ti_urp <= ti->ti_len) |
b2db9217 | 614 | tcp_pulloutofband(so, ti); |
5e74df82 | 615 | } |
87e78f19 BJ |
616 | |
617 | /* | |
2ff61f9d BJ |
618 | * Process the segment text, merging it into the TCP sequencing queue, |
619 | * and arranging for acknowledgment of receipt if necessary. | |
620 | * This process logically involves adjusting tp->rcv_wnd as data | |
621 | * is presented to the user (this happens in tcp_usrreq.c, | |
622 | * case PRU_RCVD). If a FIN has already been received on this | |
623 | * connection then we just ignore the text. | |
87e78f19 | 624 | */ |
e832edbc BJ |
625 | if ((ti->ti_len || (tiflags&TH_FIN)) && |
626 | TCPS_HAVERCVDFIN(tp->t_state) == 0) { | |
2ff61f9d | 627 | tiflags = tcp_reass(tp, ti); |
8b5a83bb BJ |
628 | if (tcpnodelack == 0) |
629 | tp->t_flags |= TF_DELACK; | |
630 | else | |
631 | tp->t_flags |= TF_ACKNOW; | |
4aed14e3 | 632 | } else { |
2b4b57cd | 633 | m_freem(m); |
e832edbc | 634 | tiflags &= ~TH_FIN; |
4aed14e3 | 635 | } |
87e78f19 BJ |
636 | |
637 | /* | |
e832edbc BJ |
638 | * If FIN is received ACK the FIN and let the user know |
639 | * that the connection is closing. | |
87e78f19 | 640 | */ |
e832edbc | 641 | if (tiflags & TH_FIN) { |
4aed14e3 BJ |
642 | if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { |
643 | socantrcvmore(so); | |
644 | tp->t_flags |= TF_ACKNOW; | |
645 | tp->rcv_nxt++; | |
646 | } | |
2ff61f9d | 647 | switch (tp->t_state) { |
87e78f19 | 648 | |
2ff61f9d BJ |
649 | /* |
650 | * In SYN_RECEIVED and ESTABLISHED STATES | |
651 | * enter the CLOSE_WAIT state. | |
53a5409e | 652 | */ |
2ff61f9d BJ |
653 | case TCPS_SYN_RECEIVED: |
654 | case TCPS_ESTABLISHED: | |
655 | tp->t_state = TCPS_CLOSE_WAIT; | |
656 | break; | |
53a5409e | 657 | |
2ff61f9d | 658 | /* |
8a13b737 BJ |
659 | * If still in FIN_WAIT_1 STATE FIN has not been acked so |
660 | * enter the CLOSING state. | |
53a5409e | 661 | */ |
2ff61f9d | 662 | case TCPS_FIN_WAIT_1: |
8a13b737 | 663 | tp->t_state = TCPS_CLOSING; |
2ff61f9d | 664 | break; |
87e78f19 | 665 | |
2ff61f9d BJ |
666 | /* |
667 | * In FIN_WAIT_2 state enter the TIME_WAIT state, | |
668 | * starting the time-wait timer, turning off the other | |
669 | * standard timers. | |
670 | */ | |
671 | case TCPS_FIN_WAIT_2: | |
4aed14e3 | 672 | tp->t_state = TCPS_TIME_WAIT; |
a6503abf | 673 | tcp_canceltimers(tp); |
405c9168 | 674 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
4aed14e3 | 675 | soisdisconnected(so); |
2ff61f9d BJ |
676 | break; |
677 | ||
53a5409e | 678 | /* |
2ff61f9d | 679 | * In TIME_WAIT state restart the 2 MSL time_wait timer. |
53a5409e | 680 | */ |
2ff61f9d | 681 | case TCPS_TIME_WAIT: |
405c9168 | 682 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 683 | break; |
8a13b737 | 684 | } |
87e78f19 | 685 | } |
4b935108 BJ |
686 | if (so->so_options & SO_DEBUG) |
687 | tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); | |
8a13b737 BJ |
688 | |
689 | /* | |
690 | * Return any desired output. | |
691 | */ | |
668cc26d | 692 | (void) tcp_output(tp); |
2ff61f9d | 693 | return; |
8a13b737 | 694 | |
2ff61f9d | 695 | dropafterack: |
8a13b737 | 696 | /* |
1e977657 BJ |
697 | * Generate an ACK dropping incoming segment if it occupies |
698 | * sequence space, where the ACK reflects our state. | |
8a13b737 | 699 | */ |
1e977657 BJ |
700 | if ((tiflags&TH_RST) || |
701 | tlen == 0 && (tiflags&(TH_SYN|TH_FIN)) == 0) | |
8a13b737 | 702 | goto drop; |
f3cdd721 BJ |
703 | if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG) |
704 | tcp_trace(TA_RESPOND, ostate, tp, &tcp_saveti, 0); | |
8e65fd66 | 705 | tcp_respond(tp, ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK); |
4b6b94ca | 706 | return; |
8a13b737 BJ |
707 | |
708 | dropwithreset: | |
8b5a83bb | 709 | if (om) |
668cc26d | 710 | (void) m_free(om); |
8a13b737 | 711 | /* |
4aed14e3 | 712 | * Generate a RST, dropping incoming segment. |
8a13b737 BJ |
713 | * Make ACK acceptable to originator of segment. |
714 | */ | |
715 | if (tiflags & TH_RST) | |
716 | goto drop; | |
717 | if (tiflags & TH_ACK) | |
8e65fd66 | 718 | tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); |
8a13b737 BJ |
719 | else { |
720 | if (tiflags & TH_SYN) | |
721 | ti->ti_len++; | |
1e977657 BJ |
722 | tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, |
723 | TH_RST|TH_ACK); | |
8a13b737 | 724 | } |
7aa16f99 SL |
725 | /* destroy temporarily created socket */ |
726 | if (dropsocket) | |
727 | (void) soabort(so); | |
4b6b94ca | 728 | return; |
8a13b737 | 729 | |
2ff61f9d | 730 | drop: |
8a13b737 BJ |
731 | /* |
732 | * Drop space held by incoming segment and return. | |
733 | */ | |
f3cdd721 BJ |
734 | if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) |
735 | tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); | |
2ff61f9d | 736 | m_freem(m); |
7aa16f99 SL |
737 | /* destroy temporarily created socket */ |
738 | if (dropsocket) | |
739 | (void) soabort(so); | |
4b935108 | 740 | return; |
2ff61f9d BJ |
741 | } |
742 | ||
8b5a83bb BJ |
743 | tcp_dooptions(tp, om) |
744 | struct tcpcb *tp; | |
745 | struct mbuf *om; | |
5e74df82 | 746 | { |
8b5a83bb BJ |
747 | register u_char *cp; |
748 | int opt, optlen, cnt; | |
749 | ||
750 | cp = mtod(om, u_char *); | |
751 | cnt = om->m_len; | |
752 | for (; cnt > 0; cnt -= optlen, cp += optlen) { | |
753 | opt = cp[0]; | |
754 | if (opt == TCPOPT_EOL) | |
755 | break; | |
756 | if (opt == TCPOPT_NOP) | |
757 | optlen = 1; | |
758 | else | |
759 | optlen = cp[1]; | |
760 | switch (opt) { | |
761 | ||
762 | default: | |
763 | break; | |
764 | ||
765 | case TCPOPT_MAXSEG: | |
766 | if (optlen != 4) | |
767 | continue; | |
768 | tp->t_maxseg = *(u_short *)(cp + 2); | |
668cc26d | 769 | tp->t_maxseg = ntohs((u_short)tp->t_maxseg); |
8b5a83bb | 770 | break; |
8b5a83bb | 771 | } |
5e74df82 | 772 | } |
668cc26d | 773 | (void) m_free(om); |
5e74df82 BJ |
774 | } |
775 | ||
b2db9217 BJ |
776 | /* |
777 | * Pull out of band byte out of a segment so | |
778 | * it doesn't appear in the user's data queue. | |
779 | * It is still reflected in the segment length for | |
780 | * sequencing purposes. | |
781 | */ | |
782 | tcp_pulloutofband(so, ti) | |
783 | struct socket *so; | |
784 | struct tcpiphdr *ti; | |
785 | { | |
786 | register struct mbuf *m; | |
1acff8ec | 787 | int cnt = ti->ti_urp - 1; |
b2db9217 BJ |
788 | |
789 | m = dtom(ti); | |
790 | while (cnt >= 0) { | |
791 | if (m->m_len > cnt) { | |
792 | char *cp = mtod(m, caddr_t) + cnt; | |
793 | struct tcpcb *tp = sototcpcb(so); | |
794 | ||
795 | tp->t_iobc = *cp; | |
796 | tp->t_oobflags |= TCPOOB_HAVEDATA; | |
668cc26d | 797 | bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); |
b2db9217 BJ |
798 | m->m_len--; |
799 | return; | |
800 | } | |
801 | cnt -= m->m_len; | |
802 | m = m->m_next; | |
803 | if (m == 0) | |
804 | break; | |
805 | } | |
806 | panic("tcp_pulloutofband"); | |
807 | } | |
808 | ||
2ff61f9d BJ |
809 | /* |
810 | * Insert segment ti into reassembly queue of tcp with | |
811 | * control block tp. Return TH_FIN if reassembly now includes | |
812 | * a segment with FIN. | |
813 | */ | |
f1b2fa5b | 814 | tcp_reass(tp, ti) |
2ff61f9d BJ |
815 | register struct tcpcb *tp; |
816 | register struct tcpiphdr *ti; | |
2ff61f9d BJ |
817 | { |
818 | register struct tcpiphdr *q; | |
8a13b737 | 819 | struct socket *so = tp->t_inpcb->inp_socket; |
e832edbc BJ |
820 | struct mbuf *m; |
821 | int flags; | |
2ff61f9d BJ |
822 | |
823 | /* | |
405c9168 BJ |
824 | * Call with ti==0 after become established to |
825 | * force pre-ESTABLISHED data up to user socket. | |
2ff61f9d | 826 | */ |
405c9168 | 827 | if (ti == 0) |
2ff61f9d | 828 | goto present; |
87e78f19 | 829 | |
2ff61f9d BJ |
830 | /* |
831 | * Find a segment which begins after this one does. | |
832 | */ | |
833 | for (q = tp->seg_next; q != (struct tcpiphdr *)tp; | |
834 | q = (struct tcpiphdr *)q->ti_next) | |
835 | if (SEQ_GT(q->ti_seq, ti->ti_seq)) | |
836 | break; | |
837 | ||
838 | /* | |
839 | * If there is a preceding segment, it may provide some of | |
840 | * our data already. If so, drop the data from the incoming | |
841 | * segment. If it provides all of our data, drop us. | |
842 | */ | |
843 | if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { | |
844 | register int i; | |
fd5dc5f0 | 845 | q = (struct tcpiphdr *)q->ti_prev; |
2ff61f9d BJ |
846 | /* conversion to int (in i) handles seq wraparound */ |
847 | i = q->ti_seq + q->ti_len - ti->ti_seq; | |
848 | if (i > 0) { | |
2b4b57cd | 849 | if (i >= ti->ti_len) |
2ff61f9d | 850 | goto drop; |
4ab1a5c3 | 851 | m_adj(dtom(ti), i); |
2b4b57cd | 852 | ti->ti_len -= i; |
2ff61f9d | 853 | ti->ti_seq += i; |
53a5409e | 854 | } |
2ff61f9d BJ |
855 | q = (struct tcpiphdr *)(q->ti_next); |
856 | } | |
87e78f19 | 857 | |
2ff61f9d BJ |
858 | /* |
859 | * While we overlap succeeding segments trim them or, | |
860 | * if they are completely covered, dequeue them. | |
861 | */ | |
fd5dc5f0 | 862 | while (q != (struct tcpiphdr *)tp) { |
2ff61f9d | 863 | register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; |
fd5dc5f0 BJ |
864 | if (i <= 0) |
865 | break; | |
2ff61f9d | 866 | if (i < q->ti_len) { |
fd5dc5f0 | 867 | q->ti_seq += i; |
2ff61f9d BJ |
868 | q->ti_len -= i; |
869 | m_adj(dtom(q), i); | |
870 | break; | |
ac5e71a1 | 871 | } |
2ff61f9d | 872 | q = (struct tcpiphdr *)q->ti_next; |
473a17a5 | 873 | m = dtom(q->ti_prev); |
2ff61f9d | 874 | remque(q->ti_prev); |
473a17a5 | 875 | m_freem(m); |
2ff61f9d | 876 | } |
87e78f19 | 877 | |
2ff61f9d BJ |
878 | /* |
879 | * Stick new segment in its place. | |
880 | */ | |
881 | insque(ti, q->ti_prev); | |
2ff61f9d | 882 | |
2ff61f9d BJ |
883 | present: |
884 | /* | |
4aed14e3 BJ |
885 | * Present data to user, advancing rcv_nxt through |
886 | * completed sequence space. | |
2ff61f9d | 887 | */ |
e832edbc | 888 | if (TCPS_HAVERCVDSYN(tp->t_state) == 0) |
4aed14e3 | 889 | return (0); |
2b4b57cd | 890 | ti = tp->seg_next; |
e832edbc BJ |
891 | if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) |
892 | return (0); | |
893 | if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) | |
894 | return (0); | |
895 | do { | |
4aed14e3 BJ |
896 | tp->rcv_nxt += ti->ti_len; |
897 | flags = ti->ti_flags & TH_FIN; | |
2b4b57cd | 898 | remque(ti); |
e832edbc | 899 | m = dtom(ti); |
2b4b57cd | 900 | ti = (struct tcpiphdr *)ti->ti_next; |
e832edbc | 901 | if (so->so_state & SS_CANTRCVMORE) |
668cc26d | 902 | m_freem(m); |
789d2a39 | 903 | else |
e832edbc BJ |
904 | sbappend(&so->so_rcv, m); |
905 | } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); | |
906 | sorwakeup(so); | |
2ff61f9d BJ |
907 | return (flags); |
908 | drop: | |
909 | m_freem(dtom(ti)); | |
e832edbc | 910 | return (0); |
d52566dd | 911 | } |