Commit | Line | Data |
---|---|---|
6e7edb25 | 1 | /* tcp_input.c 1.80 82/10/20 */ |
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; |
a8d3bf7f | 75 | #if vax || pdp11 || ns16032 |
668cc26d | 76 | ti->ti_len = htons((u_short)ti->ti_len); |
ac83b17a | 77 | #endif |
4b6b94ca | 78 | if (ti->ti_sum = in_cksum(m, len)) { |
2b4b57cd | 79 | tcpstat.tcps_badsum++; |
1e977657 BJ |
80 | if (tcpprintfs) |
81 | printf("tcp cksum %x\n", ti->ti_sum); | |
8a13b737 | 82 | goto drop; |
87e78f19 BJ |
83 | } |
84 | } | |
85 | ||
86 | /* | |
4aed14e3 | 87 | * Check that TCP offset makes sense, |
8b5a83bb | 88 | * pull out TCP options and adjust length. |
87e78f19 | 89 | */ |
2b4b57cd | 90 | off = ti->ti_off << 2; |
4b6b94ca | 91 | if (off < sizeof (struct tcphdr) || off > tlen) { |
2b4b57cd | 92 | tcpstat.tcps_badoff++; |
8a13b737 | 93 | goto drop; |
2b4b57cd | 94 | } |
1e977657 BJ |
95 | tlen -= off; |
96 | ti->ti_len = tlen; | |
8b5a83bb BJ |
97 | if (off > sizeof (struct tcphdr)) { |
98 | if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) { | |
99 | tcpstat.tcps_hdrops++; | |
100 | goto drop; | |
101 | } | |
102 | ti = mtod(m, struct tcpiphdr *); | |
103 | om = m_get(M_DONTWAIT); | |
104 | if (om == 0) | |
105 | goto drop; | |
8b5a83bb BJ |
106 | om->m_len = off - sizeof (struct tcphdr); |
107 | { caddr_t op = mtod(m, caddr_t) + sizeof (struct tcpiphdr); | |
668cc26d | 108 | bcopy(op, mtod(om, caddr_t), (unsigned)om->m_len); |
8b5a83bb | 109 | m->m_len -= om->m_len; |
668cc26d SL |
110 | bcopy(op+om->m_len, op, |
111 | (unsigned)(m->m_len-sizeof (struct tcpiphdr))); | |
8b5a83bb BJ |
112 | } |
113 | } | |
2ff61f9d | 114 | tiflags = ti->ti_flags; |
2b4b57cd | 115 | |
795e0416 | 116 | /* |
1e977657 | 117 | * Drop TCP and IP headers. |
795e0416 BJ |
118 | */ |
119 | off += sizeof (struct ip); | |
120 | m->m_off += off; | |
121 | m->m_len -= off; | |
122 | ||
a8d3bf7f | 123 | #if vax || pdp11 || ns16032 |
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); | |
4b6b94ca | 131 | #endif |
8a13b737 | 132 | |
2b4b57cd | 133 | /* |
8075bb0e | 134 | * Locate pcb for segment. |
2b4b57cd | 135 | */ |
2ff61f9d | 136 | inp = in_pcblookup |
ebcadd38 BJ |
137 | (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport, |
138 | INPLOOKUP_WILDCARD); | |
2ff61f9d BJ |
139 | |
140 | /* | |
141 | * If the state is CLOSED (i.e., TCB does not exist) then | |
4aed14e3 | 142 | * all data in the incoming segment is discarded. |
2ff61f9d | 143 | */ |
22856bb8 | 144 | if (inp == 0) |
8a13b737 | 145 | goto dropwithreset; |
2ff61f9d | 146 | tp = intotcpcb(inp); |
22856bb8 | 147 | if (tp == 0) |
8a13b737 | 148 | goto dropwithreset; |
f1b2fa5b | 149 | so = inp->inp_socket; |
4b935108 BJ |
150 | if (so->so_options & SO_DEBUG) { |
151 | ostate = tp->t_state; | |
152 | tcp_saveti = *ti; | |
153 | } | |
ebf42a75 BJ |
154 | if (so->so_options & SO_ACCEPTCONN) { |
155 | so = sonewconn(so); | |
156 | if (so == 0) | |
157 | goto drop; | |
158 | inp = (struct inpcb *)so->so_pcb; | |
159 | inp->inp_laddr = ti->ti_dst; | |
160 | inp->inp_lport = ti->ti_dport; | |
161 | tp = intotcpcb(inp); | |
162 | tp->t_state = TCPS_LISTEN; | |
163 | } | |
87e78f19 | 164 | |
405c9168 BJ |
165 | /* |
166 | * Segment received on connection. | |
167 | * Reset idle time and keep-alive timer. | |
168 | */ | |
169 | tp->t_idle = 0; | |
170 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; | |
171 | ||
8b5a83bb BJ |
172 | /* |
173 | * Process options. | |
174 | */ | |
175 | if (om) { | |
176 | tcp_dooptions(tp, om); | |
177 | om = 0; | |
178 | } | |
179 | ||
87e78f19 | 180 | /* |
8a13b737 BJ |
181 | * Calculate amount of space in receive window, |
182 | * and then do TCP input processing. | |
87e78f19 | 183 | */ |
8a13b737 | 184 | tp->rcv_wnd = sbspace(&so->so_rcv); |
4b6b94ca BJ |
185 | if (tp->rcv_wnd < 0) |
186 | tp->rcv_wnd = 0; | |
2ff61f9d | 187 | |
87e78f19 BJ |
188 | switch (tp->t_state) { |
189 | ||
2ff61f9d BJ |
190 | /* |
191 | * If the state is LISTEN then ignore segment if it contains an RST. | |
192 | * If the segment contains an ACK then it is bad and send a RST. | |
193 | * If it does not contain a SYN then it is not interesting; drop it. | |
8a13b737 | 194 | * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial |
2ff61f9d | 195 | * tp->iss, and send a segment: |
8a13b737 | 196 | * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> |
2ff61f9d BJ |
197 | * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. |
198 | * Fill in remote peer address fields if not previously specified. | |
199 | * Enter SYN_RECEIVED state, and process any other fields of this | |
4aed14e3 | 200 | * segment in this state. |
2ff61f9d | 201 | */ |
8075bb0e | 202 | case TCPS_LISTEN: { |
a8d3bf7f | 203 | struct mbuf *am = m_get(M_DONTWAIT); |
8075bb0e BJ |
204 | register struct sockaddr_in *sin; |
205 | ||
a8d3bf7f | 206 | if (am == 0) |
8075bb0e | 207 | goto drop; |
a8d3bf7f | 208 | am->m_len = sizeof (struct sockaddr_in); |
2ff61f9d BJ |
209 | if (tiflags & TH_RST) |
210 | goto drop; | |
22856bb8 | 211 | if (tiflags & TH_ACK) |
8a13b737 | 212 | goto dropwithreset; |
22856bb8 | 213 | if ((tiflags & TH_SYN) == 0) |
2ff61f9d | 214 | goto drop; |
a8d3bf7f | 215 | sin = mtod(am, struct sockaddr_in *); |
8075bb0e BJ |
216 | sin->sin_family = AF_INET; |
217 | sin->sin_addr = ti->ti_src; | |
218 | sin->sin_port = ti->ti_sport; | |
ebcadd38 BJ |
219 | laddr = inp->inp_laddr; |
220 | if (inp->inp_laddr.s_addr == 0) | |
221 | inp->inp_laddr = ti->ti_dst; | |
a8d3bf7f | 222 | if (in_pcbconnect(inp, am)) { |
ebcadd38 | 223 | inp->inp_laddr = laddr; |
a8d3bf7f | 224 | m_free(am); |
4aed14e3 | 225 | goto drop; |
ebcadd38 | 226 | } |
a8d3bf7f | 227 | m_free(am); |
4aed14e3 BJ |
228 | tp->t_template = tcp_template(tp); |
229 | if (tp->t_template == 0) { | |
230 | in_pcbdisconnect(inp); | |
ebcadd38 | 231 | inp->inp_laddr = laddr; |
93f92b1d | 232 | tp = 0; |
4aed14e3 BJ |
233 | goto drop; |
234 | } | |
8a13b737 | 235 | tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; |
2ff61f9d | 236 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
237 | tcp_sendseqinit(tp); |
238 | tcp_rcvseqinit(tp); | |
2ff61f9d | 239 | tp->t_state = TCPS_SYN_RECEIVED; |
4aed14e3 | 240 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; |
8a13b737 | 241 | goto trimthenstep6; |
8075bb0e | 242 | } |
87e78f19 | 243 | |
2ff61f9d BJ |
244 | /* |
245 | * If the state is SYN_SENT: | |
246 | * if seg contains an ACK, but not for our SYN, drop the input. | |
247 | * if seg contains a RST, then drop the connection. | |
248 | * if seg does not contain SYN, then drop it. | |
249 | * Otherwise this is an acceptable SYN segment | |
250 | * initialize tp->rcv_nxt and tp->irs | |
251 | * if seg contains ack then advance tp->snd_una | |
252 | * if SYN has been acked change to ESTABLISHED else SYN_RCVD state | |
253 | * arrange for segment to be acked (eventually) | |
254 | * continue processing rest of data/controls, beginning with URG | |
255 | */ | |
256 | case TCPS_SYN_SENT: | |
257 | if ((tiflags & TH_ACK) && | |
22856bb8 BJ |
258 | /* this should be SEQ_LT; is SEQ_LEQ for BBN vax TCP only */ |
259 | (SEQ_LT(ti->ti_ack, tp->iss) || | |
4b6b94ca | 260 | SEQ_GT(ti->ti_ack, tp->snd_max))) |
8a13b737 | 261 | goto dropwithreset; |
2ff61f9d | 262 | if (tiflags & TH_RST) { |
93f92b1d | 263 | if (tiflags & TH_ACK) { |
4b935108 | 264 | tcp_drop(tp, ECONNREFUSED); |
93f92b1d BJ |
265 | tp = 0; |
266 | } | |
2ff61f9d | 267 | goto drop; |
87e78f19 | 268 | } |
2ff61f9d BJ |
269 | if ((tiflags & TH_SYN) == 0) |
270 | goto drop; | |
4b6b94ca | 271 | tp->snd_una = ti->ti_ack; |
b8977237 BJ |
272 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
273 | tp->snd_nxt = tp->snd_una; | |
4aed14e3 | 274 | tp->t_timer[TCPT_REXMT] = 0; |
2ff61f9d | 275 | tp->irs = ti->ti_seq; |
8a13b737 BJ |
276 | tcp_rcvseqinit(tp); |
277 | tp->t_flags |= TF_ACKNOW; | |
405c9168 | 278 | if (SEQ_GT(tp->snd_una, tp->iss)) { |
4aed14e3 | 279 | soisconnected(so); |
2ff61f9d | 280 | tp->t_state = TCPS_ESTABLISHED; |
405c9168 BJ |
281 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
282 | } else | |
8a13b737 BJ |
283 | tp->t_state = TCPS_SYN_RECEIVED; |
284 | goto trimthenstep6; | |
285 | ||
286 | trimthenstep6: | |
287 | /* | |
4b6b94ca | 288 | * Advance ti->ti_seq to correspond to first data byte. |
8a13b737 BJ |
289 | * If data, trim to stay within window, |
290 | * dropping FIN if necessary. | |
291 | */ | |
4b6b94ca | 292 | ti->ti_seq++; |
8a13b737 BJ |
293 | if (ti->ti_len > tp->rcv_wnd) { |
294 | todrop = ti->ti_len - tp->rcv_wnd; | |
295 | m_adj(m, -todrop); | |
296 | ti->ti_len = tp->rcv_wnd; | |
297 | ti->ti_flags &= ~TH_FIN; | |
87e78f19 | 298 | } |
e832edbc | 299 | tp->snd_wl1 = ti->ti_seq - 1; |
8a13b737 | 300 | goto step6; |
2ff61f9d | 301 | } |
87e78f19 | 302 | |
2ff61f9d BJ |
303 | /* |
304 | * States other than LISTEN or SYN_SENT. | |
305 | * First check that at least some bytes of segment are within | |
306 | * receive window. | |
307 | */ | |
308 | if (tp->rcv_wnd == 0) { | |
309 | /* | |
310 | * If window is closed can only take segments at | |
4b6b94ca | 311 | * window edge, and have to drop data and PUSH from |
2ff61f9d BJ |
312 | * incoming segments. |
313 | */ | |
22856bb8 | 314 | if (tp->rcv_nxt != ti->ti_seq) |
2ff61f9d | 315 | goto dropafterack; |
8a13b737 | 316 | if (ti->ti_len > 0) { |
fd5dc5f0 | 317 | m_adj(m, ti->ti_len); |
8a13b737 BJ |
318 | ti->ti_len = 0; |
319 | ti->ti_flags &= ~(TH_PUSH|TH_FIN); | |
87e78f19 | 320 | } |
2ff61f9d BJ |
321 | } else { |
322 | /* | |
4b6b94ca | 323 | * If segment begins before rcv_nxt, drop leading |
2ff61f9d BJ |
324 | * data (and SYN); if nothing left, just ack. |
325 | */ | |
fd5dc5f0 BJ |
326 | todrop = tp->rcv_nxt - ti->ti_seq; |
327 | if (todrop > 0) { | |
8a13b737 | 328 | if (tiflags & TH_SYN) { |
22856bb8 | 329 | tiflags &= ~TH_SYN; |
fd5dc5f0 | 330 | ti->ti_flags &= ~TH_SYN; |
8a13b737 BJ |
331 | ti->ti_seq++; |
332 | if (ti->ti_urp > 1) | |
333 | ti->ti_urp--; | |
334 | else | |
335 | tiflags &= ~TH_URG; | |
336 | todrop--; | |
337 | } | |
1e977657 BJ |
338 | if (todrop > ti->ti_len || |
339 | todrop == ti->ti_len && (tiflags&TH_FIN) == 0) | |
2ff61f9d BJ |
340 | goto dropafterack; |
341 | m_adj(m, todrop); | |
342 | ti->ti_seq += todrop; | |
343 | ti->ti_len -= todrop; | |
8a13b737 BJ |
344 | if (ti->ti_urp > todrop) |
345 | ti->ti_urp -= todrop; | |
346 | else { | |
347 | tiflags &= ~TH_URG; | |
fd5dc5f0 BJ |
348 | ti->ti_flags &= ~TH_URG; |
349 | ti->ti_urp = 0; | |
8a13b737 | 350 | } |
2ff61f9d BJ |
351 | } |
352 | /* | |
353 | * If segment ends after window, drop trailing data | |
8a13b737 | 354 | * (and PUSH and FIN); if nothing left, just ACK. |
2ff61f9d | 355 | */ |
fd5dc5f0 BJ |
356 | todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); |
357 | if (todrop > 0) { | |
1e977657 | 358 | if (todrop >= ti->ti_len) |
2ff61f9d BJ |
359 | goto dropafterack; |
360 | m_adj(m, -todrop); | |
361 | ti->ti_len -= todrop; | |
8a13b737 | 362 | ti->ti_flags &= ~(TH_PUSH|TH_FIN); |
87e78f19 | 363 | } |
87e78f19 | 364 | } |
87e78f19 | 365 | |
dd020fc8 BJ |
366 | /* |
367 | * If a segment is received on a connection after the | |
368 | * user processes are gone, then RST the other end. | |
369 | */ | |
ebf42a75 | 370 | if (so->so_state & SS_NOFDREF) { |
dd020fc8 | 371 | tcp_close(tp); |
9d0b428a | 372 | tp = 0; |
dd020fc8 BJ |
373 | goto dropwithreset; |
374 | } | |
375 | ||
87e78f19 | 376 | /* |
2ff61f9d BJ |
377 | * If the RST bit is set examine the state: |
378 | * SYN_RECEIVED STATE: | |
379 | * If passive open, return to LISTEN state. | |
380 | * If active open, inform user that connection was refused. | |
381 | * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: | |
382 | * Inform user that connection was reset, and close tcb. | |
383 | * CLOSING, LAST_ACK, TIME_WAIT STATES | |
384 | * Close the tcb. | |
87e78f19 | 385 | */ |
2ff61f9d | 386 | if (tiflags&TH_RST) switch (tp->t_state) { |
4b935108 | 387 | |
2ff61f9d | 388 | case TCPS_SYN_RECEIVED: |
8a13b737 | 389 | tcp_drop(tp, ECONNREFUSED); |
93f92b1d | 390 | tp = 0; |
2ff61f9d BJ |
391 | goto drop; |
392 | ||
393 | case TCPS_ESTABLISHED: | |
394 | case TCPS_FIN_WAIT_1: | |
395 | case TCPS_FIN_WAIT_2: | |
396 | case TCPS_CLOSE_WAIT: | |
397 | tcp_drop(tp, ECONNRESET); | |
93f92b1d | 398 | tp = 0; |
2ff61f9d BJ |
399 | goto drop; |
400 | ||
401 | case TCPS_CLOSING: | |
402 | case TCPS_LAST_ACK: | |
403 | case TCPS_TIME_WAIT: | |
404 | tcp_close(tp); | |
93f92b1d | 405 | tp = 0; |
2ff61f9d | 406 | goto drop; |
87e78f19 | 407 | } |
87e78f19 BJ |
408 | |
409 | /* | |
2ff61f9d BJ |
410 | * If a SYN is in the window, then this is an |
411 | * error and we send an RST and drop the connection. | |
412 | */ | |
413 | if (tiflags & TH_SYN) { | |
4b6b94ca | 414 | tcp_drop(tp, ECONNRESET); |
9d0b428a | 415 | tp = 0; |
8a13b737 | 416 | goto dropwithreset; |
2ff61f9d BJ |
417 | } |
418 | ||
419 | /* | |
420 | * If the ACK bit is off we drop the segment and return. | |
421 | */ | |
8a13b737 | 422 | if ((tiflags & TH_ACK) == 0) |
2ff61f9d BJ |
423 | goto drop; |
424 | ||
425 | /* | |
426 | * Ack processing. | |
87e78f19 | 427 | */ |
87e78f19 BJ |
428 | switch (tp->t_state) { |
429 | ||
2ff61f9d BJ |
430 | /* |
431 | * In SYN_RECEIVED state if the ack ACKs our SYN then enter | |
432 | * ESTABLISHED state and continue processing, othewise | |
433 | * send an RST. | |
434 | */ | |
435 | case TCPS_SYN_RECEIVED: | |
8a13b737 | 436 | if (SEQ_GT(tp->snd_una, ti->ti_ack) || |
4b6b94ca | 437 | SEQ_GT(ti->ti_ack, tp->snd_max)) |
8a13b737 | 438 | goto dropwithreset; |
4aed14e3 | 439 | tp->snd_una++; /* SYN acked */ |
b8977237 BJ |
440 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
441 | tp->snd_nxt = tp->snd_una; | |
4aed14e3 | 442 | tp->t_timer[TCPT_REXMT] = 0; |
8a13b737 BJ |
443 | soisconnected(so); |
444 | tp->t_state = TCPS_ESTABLISHED; | |
405c9168 | 445 | (void) tcp_reass(tp, (struct tcpiphdr *)0); |
4aed14e3 | 446 | tp->snd_wl1 = ti->ti_seq - 1; |
8a13b737 | 447 | /* fall into ... */ |
87e78f19 | 448 | |
2ff61f9d BJ |
449 | /* |
450 | * In ESTABLISHED state: drop duplicate ACKs; ACK out of range | |
451 | * ACKs. If the ack is in the range | |
4b6b94ca | 452 | * tp->snd_una < ti->ti_ack <= tp->snd_max |
2ff61f9d BJ |
453 | * then advance tp->snd_una to ti->ti_ack and drop |
454 | * data from the retransmission queue. If this ACK reflects | |
455 | * more up to date window information we update our window information. | |
456 | */ | |
457 | case TCPS_ESTABLISHED: | |
458 | case TCPS_FIN_WAIT_1: | |
459 | case TCPS_FIN_WAIT_2: | |
460 | case TCPS_CLOSE_WAIT: | |
461 | case TCPS_CLOSING: | |
4aed14e3 BJ |
462 | case TCPS_LAST_ACK: |
463 | case TCPS_TIME_WAIT: | |
8a13b737 BJ |
464 | #define ourfinisacked (acked > 0) |
465 | ||
4aed14e3 | 466 | if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) |
2ff61f9d | 467 | break; |
22856bb8 | 468 | if (SEQ_GT(ti->ti_ack, tp->snd_max)) |
2ff61f9d | 469 | goto dropafterack; |
8a13b737 | 470 | acked = ti->ti_ack - tp->snd_una; |
dd020fc8 BJ |
471 | |
472 | /* | |
473 | * If transmit timer is running and timed sequence | |
474 | * number was acked, update smoothed round trip time. | |
475 | */ | |
476 | if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { | |
477 | if (tp->t_srtt == 0) | |
478 | tp->t_srtt = tp->t_rtt; | |
479 | else | |
480 | tp->t_srtt = | |
481 | tcp_alpha * tp->t_srtt + | |
482 | (1 - tcp_alpha) * tp->t_rtt; | |
483 | /* printf("rtt %d srtt*100 now %d\n", tp->t_rtt, (int)(tp->t_srtt*100)); */ | |
484 | tp->t_rtt = 0; | |
485 | } | |
486 | ||
6703c41f | 487 | if (ti->ti_ack == tp->snd_max) |
4aed14e3 | 488 | tp->t_timer[TCPT_REXMT] = 0; |
6703c41f | 489 | else { |
4aed14e3 BJ |
490 | TCPT_RANGESET(tp->t_timer[TCPT_REXMT], |
491 | tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); | |
dd020fc8 | 492 | tp->t_rtt = 1; |
22856bb8 | 493 | tp->t_rxtshift = 0; |
8a13b737 | 494 | } |
6703c41f BJ |
495 | if (acked > so->so_snd.sb_cc) { |
496 | sbdrop(&so->so_snd, so->so_snd.sb_cc); | |
497 | tp->snd_wnd -= so->so_snd.sb_cc; | |
498 | } else { | |
668cc26d | 499 | sbdrop(&so->so_snd, acked); |
6703c41f BJ |
500 | tp->snd_wnd -= acked; |
501 | acked = 0; | |
502 | } | |
5744ed2b | 503 | if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel) |
22856bb8 | 504 | sowwakeup(so); |
4b6b94ca | 505 | tp->snd_una = ti->ti_ack; |
b8977237 BJ |
506 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
507 | tp->snd_nxt = tp->snd_una; | |
405c9168 | 508 | |
87e78f19 BJ |
509 | switch (tp->t_state) { |
510 | ||
2ff61f9d BJ |
511 | /* |
512 | * In FIN_WAIT_1 STATE in addition to the processing | |
513 | * for the ESTABLISHED state if our FIN is now acknowledged | |
8a13b737 | 514 | * then enter FIN_WAIT_2. |
2ff61f9d BJ |
515 | */ |
516 | case TCPS_FIN_WAIT_1: | |
fdae4427 BJ |
517 | if (ourfinisacked) { |
518 | /* | |
519 | * If we can't receive any more | |
520 | * data, then closing user can proceed. | |
521 | */ | |
522 | if (so->so_state & SS_CANTRCVMORE) | |
523 | soisdisconnected(so); | |
8a13b737 | 524 | tp->t_state = TCPS_FIN_WAIT_2; |
fdae4427 | 525 | } |
87e78f19 BJ |
526 | break; |
527 | ||
2ff61f9d BJ |
528 | /* |
529 | * In CLOSING STATE in addition to the processing for | |
530 | * the ESTABLISHED state if the ACK acknowledges our FIN | |
531 | * then enter the TIME-WAIT state, otherwise ignore | |
532 | * the segment. | |
533 | */ | |
534 | case TCPS_CLOSING: | |
4aed14e3 | 535 | if (ourfinisacked) { |
2ff61f9d | 536 | tp->t_state = TCPS_TIME_WAIT; |
4aed14e3 BJ |
537 | tcp_canceltimers(tp); |
538 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; | |
539 | soisdisconnected(so); | |
540 | } | |
541 | break; | |
87e78f19 | 542 | |
2ff61f9d | 543 | /* |
8a13b737 BJ |
544 | * The only thing that can arrive in LAST_ACK state |
545 | * is an acknowledgment of our FIN. If our FIN is now | |
546 | * acknowledged, delete the TCB, enter the closed state | |
547 | * and return. | |
2ff61f9d BJ |
548 | */ |
549 | case TCPS_LAST_ACK: | |
93f92b1d | 550 | if (ourfinisacked) { |
2ff61f9d | 551 | tcp_close(tp); |
93f92b1d BJ |
552 | tp = 0; |
553 | } | |
2ff61f9d | 554 | goto drop; |
87e78f19 | 555 | |
2ff61f9d BJ |
556 | /* |
557 | * In TIME_WAIT state the only thing that should arrive | |
558 | * is a retransmission of the remote FIN. Acknowledge | |
559 | * it and restart the finack timer. | |
560 | */ | |
561 | case TCPS_TIME_WAIT: | |
405c9168 | 562 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 563 | goto dropafterack; |
87e78f19 | 564 | } |
8a13b737 BJ |
565 | #undef ourfinisacked |
566 | } | |
87e78f19 | 567 | |
2ff61f9d | 568 | step6: |
4aed14e3 BJ |
569 | /* |
570 | * Update window information. | |
571 | */ | |
22856bb8 | 572 | if (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && |
8e65fd66 | 573 | (SEQ_LT(tp->snd_wl2, ti->ti_ack) || |
22856bb8 | 574 | tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd)) { |
4aed14e3 BJ |
575 | tp->snd_wnd = ti->ti_win; |
576 | tp->snd_wl1 = ti->ti_seq; | |
577 | tp->snd_wl2 = ti->ti_ack; | |
a8d3bf7f | 578 | if (tp->snd_wnd != 0) |
4aed14e3 BJ |
579 | tp->t_timer[TCPT_PERSIST] = 0; |
580 | } | |
4aed14e3 | 581 | |
2ff61f9d | 582 | /* |
b2db9217 | 583 | * Process segments with URG. |
2ff61f9d | 584 | */ |
9c811062 BJ |
585 | if ((tiflags & TH_URG) && ti->ti_urp && |
586 | TCPS_HAVERCVDFIN(tp->t_state) == 0) { | |
b2db9217 BJ |
587 | /* |
588 | * If this segment advances the known urgent pointer, | |
589 | * then mark the data stream. This should not happen | |
590 | * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since | |
591 | * a FIN has been received from the remote side. | |
592 | * In these states we ignore the URG. | |
593 | */ | |
594 | if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { | |
595 | tp->rcv_up = ti->ti_seq + ti->ti_urp; | |
596 | so->so_oobmark = so->so_rcv.sb_cc + | |
597 | (tp->rcv_up - tp->rcv_nxt) - 1; | |
598 | if (so->so_oobmark == 0) | |
599 | so->so_state |= SS_RCVATMARK; | |
77a4e3ca | 600 | sohasoutofband(so); |
b2db9217 BJ |
601 | tp->t_oobflags &= ~TCPOOB_HAVEDATA; |
602 | } | |
603 | /* | |
604 | * Remove out of band data so doesn't get presented to user. | |
605 | * This can happen independent of advancing the URG pointer, | |
606 | * but if two URG's are pending at once, some out-of-band | |
607 | * data may creep in... ick. | |
608 | */ | |
ebf42a75 | 609 | if (ti->ti_urp <= ti->ti_len) |
b2db9217 | 610 | tcp_pulloutofband(so, ti); |
5e74df82 | 611 | } |
87e78f19 BJ |
612 | |
613 | /* | |
2ff61f9d BJ |
614 | * Process the segment text, merging it into the TCP sequencing queue, |
615 | * and arranging for acknowledgment of receipt if necessary. | |
616 | * This process logically involves adjusting tp->rcv_wnd as data | |
617 | * is presented to the user (this happens in tcp_usrreq.c, | |
618 | * case PRU_RCVD). If a FIN has already been received on this | |
619 | * connection then we just ignore the text. | |
87e78f19 | 620 | */ |
e832edbc BJ |
621 | if ((ti->ti_len || (tiflags&TH_FIN)) && |
622 | TCPS_HAVERCVDFIN(tp->t_state) == 0) { | |
2ff61f9d | 623 | tiflags = tcp_reass(tp, ti); |
8b5a83bb BJ |
624 | if (tcpnodelack == 0) |
625 | tp->t_flags |= TF_DELACK; | |
626 | else | |
627 | tp->t_flags |= TF_ACKNOW; | |
4aed14e3 | 628 | } else { |
2b4b57cd | 629 | m_freem(m); |
e832edbc | 630 | tiflags &= ~TH_FIN; |
4aed14e3 | 631 | } |
87e78f19 BJ |
632 | |
633 | /* | |
e832edbc BJ |
634 | * If FIN is received ACK the FIN and let the user know |
635 | * that the connection is closing. | |
87e78f19 | 636 | */ |
e832edbc | 637 | if (tiflags & TH_FIN) { |
4aed14e3 BJ |
638 | if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { |
639 | socantrcvmore(so); | |
640 | tp->t_flags |= TF_ACKNOW; | |
641 | tp->rcv_nxt++; | |
642 | } | |
2ff61f9d | 643 | switch (tp->t_state) { |
87e78f19 | 644 | |
2ff61f9d BJ |
645 | /* |
646 | * In SYN_RECEIVED and ESTABLISHED STATES | |
647 | * enter the CLOSE_WAIT state. | |
53a5409e | 648 | */ |
2ff61f9d BJ |
649 | case TCPS_SYN_RECEIVED: |
650 | case TCPS_ESTABLISHED: | |
651 | tp->t_state = TCPS_CLOSE_WAIT; | |
652 | break; | |
53a5409e | 653 | |
2ff61f9d | 654 | /* |
8a13b737 BJ |
655 | * If still in FIN_WAIT_1 STATE FIN has not been acked so |
656 | * enter the CLOSING state. | |
53a5409e | 657 | */ |
2ff61f9d | 658 | case TCPS_FIN_WAIT_1: |
8a13b737 | 659 | tp->t_state = TCPS_CLOSING; |
2ff61f9d | 660 | break; |
87e78f19 | 661 | |
2ff61f9d BJ |
662 | /* |
663 | * In FIN_WAIT_2 state enter the TIME_WAIT state, | |
664 | * starting the time-wait timer, turning off the other | |
665 | * standard timers. | |
666 | */ | |
667 | case TCPS_FIN_WAIT_2: | |
4aed14e3 | 668 | tp->t_state = TCPS_TIME_WAIT; |
a6503abf | 669 | tcp_canceltimers(tp); |
405c9168 | 670 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
4aed14e3 | 671 | soisdisconnected(so); |
2ff61f9d BJ |
672 | break; |
673 | ||
53a5409e | 674 | /* |
2ff61f9d | 675 | * In TIME_WAIT state restart the 2 MSL time_wait timer. |
53a5409e | 676 | */ |
2ff61f9d | 677 | case TCPS_TIME_WAIT: |
405c9168 | 678 | tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; |
2ff61f9d | 679 | break; |
8a13b737 | 680 | } |
87e78f19 | 681 | } |
4b935108 BJ |
682 | if (so->so_options & SO_DEBUG) |
683 | tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); | |
8a13b737 BJ |
684 | |
685 | /* | |
686 | * Return any desired output. | |
687 | */ | |
668cc26d | 688 | (void) tcp_output(tp); |
2ff61f9d | 689 | return; |
8a13b737 | 690 | |
2ff61f9d | 691 | dropafterack: |
8a13b737 | 692 | /* |
1e977657 BJ |
693 | * Generate an ACK dropping incoming segment if it occupies |
694 | * sequence space, where the ACK reflects our state. | |
8a13b737 | 695 | */ |
1e977657 BJ |
696 | if ((tiflags&TH_RST) || |
697 | tlen == 0 && (tiflags&(TH_SYN|TH_FIN)) == 0) | |
8a13b737 | 698 | goto drop; |
f3cdd721 BJ |
699 | if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG) |
700 | tcp_trace(TA_RESPOND, ostate, tp, &tcp_saveti, 0); | |
8e65fd66 | 701 | tcp_respond(tp, ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK); |
4b6b94ca | 702 | return; |
8a13b737 BJ |
703 | |
704 | dropwithreset: | |
8b5a83bb | 705 | if (om) |
668cc26d | 706 | (void) m_free(om); |
8a13b737 | 707 | /* |
4aed14e3 | 708 | * Generate a RST, dropping incoming segment. |
8a13b737 BJ |
709 | * Make ACK acceptable to originator of segment. |
710 | */ | |
711 | if (tiflags & TH_RST) | |
712 | goto drop; | |
713 | if (tiflags & TH_ACK) | |
8e65fd66 | 714 | tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); |
8a13b737 BJ |
715 | else { |
716 | if (tiflags & TH_SYN) | |
717 | ti->ti_len++; | |
1e977657 BJ |
718 | tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, |
719 | TH_RST|TH_ACK); | |
8a13b737 | 720 | } |
4b6b94ca | 721 | return; |
8a13b737 | 722 | |
2ff61f9d | 723 | drop: |
8a13b737 BJ |
724 | /* |
725 | * Drop space held by incoming segment and return. | |
726 | */ | |
f3cdd721 BJ |
727 | if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) |
728 | tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); | |
2ff61f9d | 729 | m_freem(m); |
4b935108 | 730 | return; |
2ff61f9d BJ |
731 | } |
732 | ||
8b5a83bb BJ |
733 | tcp_dooptions(tp, om) |
734 | struct tcpcb *tp; | |
735 | struct mbuf *om; | |
5e74df82 | 736 | { |
8b5a83bb BJ |
737 | register u_char *cp; |
738 | int opt, optlen, cnt; | |
739 | ||
740 | cp = mtod(om, u_char *); | |
741 | cnt = om->m_len; | |
742 | for (; cnt > 0; cnt -= optlen, cp += optlen) { | |
743 | opt = cp[0]; | |
744 | if (opt == TCPOPT_EOL) | |
745 | break; | |
746 | if (opt == TCPOPT_NOP) | |
747 | optlen = 1; | |
748 | else | |
749 | optlen = cp[1]; | |
750 | switch (opt) { | |
751 | ||
752 | default: | |
753 | break; | |
754 | ||
755 | case TCPOPT_MAXSEG: | |
756 | if (optlen != 4) | |
757 | continue; | |
758 | tp->t_maxseg = *(u_short *)(cp + 2); | |
a8d3bf7f | 759 | #if vax || pdp11 || ns16032 |
668cc26d | 760 | tp->t_maxseg = ntohs((u_short)tp->t_maxseg); |
8b5a83bb BJ |
761 | #endif |
762 | break; | |
8b5a83bb | 763 | } |
5e74df82 | 764 | } |
668cc26d | 765 | (void) m_free(om); |
5e74df82 BJ |
766 | } |
767 | ||
b2db9217 BJ |
768 | /* |
769 | * Pull out of band byte out of a segment so | |
770 | * it doesn't appear in the user's data queue. | |
771 | * It is still reflected in the segment length for | |
772 | * sequencing purposes. | |
773 | */ | |
774 | tcp_pulloutofband(so, ti) | |
775 | struct socket *so; | |
776 | struct tcpiphdr *ti; | |
777 | { | |
778 | register struct mbuf *m; | |
1acff8ec | 779 | int cnt = ti->ti_urp - 1; |
b2db9217 BJ |
780 | |
781 | m = dtom(ti); | |
782 | while (cnt >= 0) { | |
783 | if (m->m_len > cnt) { | |
784 | char *cp = mtod(m, caddr_t) + cnt; | |
785 | struct tcpcb *tp = sototcpcb(so); | |
786 | ||
787 | tp->t_iobc = *cp; | |
788 | tp->t_oobflags |= TCPOOB_HAVEDATA; | |
668cc26d | 789 | bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); |
b2db9217 BJ |
790 | m->m_len--; |
791 | return; | |
792 | } | |
793 | cnt -= m->m_len; | |
794 | m = m->m_next; | |
795 | if (m == 0) | |
796 | break; | |
797 | } | |
798 | panic("tcp_pulloutofband"); | |
799 | } | |
800 | ||
2ff61f9d BJ |
801 | /* |
802 | * Insert segment ti into reassembly queue of tcp with | |
803 | * control block tp. Return TH_FIN if reassembly now includes | |
804 | * a segment with FIN. | |
805 | */ | |
f1b2fa5b | 806 | tcp_reass(tp, ti) |
2ff61f9d BJ |
807 | register struct tcpcb *tp; |
808 | register struct tcpiphdr *ti; | |
2ff61f9d BJ |
809 | { |
810 | register struct tcpiphdr *q; | |
8a13b737 | 811 | struct socket *so = tp->t_inpcb->inp_socket; |
e832edbc BJ |
812 | struct mbuf *m; |
813 | int flags; | |
2ff61f9d BJ |
814 | |
815 | /* | |
405c9168 BJ |
816 | * Call with ti==0 after become established to |
817 | * force pre-ESTABLISHED data up to user socket. | |
2ff61f9d | 818 | */ |
405c9168 | 819 | if (ti == 0) |
2ff61f9d | 820 | goto present; |
87e78f19 | 821 | |
2ff61f9d BJ |
822 | /* |
823 | * Find a segment which begins after this one does. | |
824 | */ | |
825 | for (q = tp->seg_next; q != (struct tcpiphdr *)tp; | |
826 | q = (struct tcpiphdr *)q->ti_next) | |
827 | if (SEQ_GT(q->ti_seq, ti->ti_seq)) | |
828 | break; | |
829 | ||
830 | /* | |
831 | * If there is a preceding segment, it may provide some of | |
832 | * our data already. If so, drop the data from the incoming | |
833 | * segment. If it provides all of our data, drop us. | |
834 | */ | |
835 | if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { | |
836 | register int i; | |
fd5dc5f0 | 837 | q = (struct tcpiphdr *)q->ti_prev; |
2ff61f9d BJ |
838 | /* conversion to int (in i) handles seq wraparound */ |
839 | i = q->ti_seq + q->ti_len - ti->ti_seq; | |
840 | if (i > 0) { | |
2b4b57cd | 841 | if (i >= ti->ti_len) |
2ff61f9d | 842 | goto drop; |
4ab1a5c3 | 843 | m_adj(dtom(ti), i); |
2b4b57cd | 844 | ti->ti_len -= i; |
2ff61f9d | 845 | ti->ti_seq += i; |
53a5409e | 846 | } |
2ff61f9d BJ |
847 | q = (struct tcpiphdr *)(q->ti_next); |
848 | } | |
87e78f19 | 849 | |
2ff61f9d BJ |
850 | /* |
851 | * While we overlap succeeding segments trim them or, | |
852 | * if they are completely covered, dequeue them. | |
853 | */ | |
fd5dc5f0 | 854 | while (q != (struct tcpiphdr *)tp) { |
2ff61f9d | 855 | register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; |
fd5dc5f0 BJ |
856 | if (i <= 0) |
857 | break; | |
2ff61f9d | 858 | if (i < q->ti_len) { |
fd5dc5f0 | 859 | q->ti_seq += i; |
2ff61f9d BJ |
860 | q->ti_len -= i; |
861 | m_adj(dtom(q), i); | |
862 | break; | |
ac5e71a1 | 863 | } |
2ff61f9d | 864 | q = (struct tcpiphdr *)q->ti_next; |
473a17a5 | 865 | m = dtom(q->ti_prev); |
2ff61f9d | 866 | remque(q->ti_prev); |
473a17a5 | 867 | m_freem(m); |
2ff61f9d | 868 | } |
87e78f19 | 869 | |
2ff61f9d BJ |
870 | /* |
871 | * Stick new segment in its place. | |
872 | */ | |
873 | insque(ti, q->ti_prev); | |
2ff61f9d | 874 | |
2ff61f9d BJ |
875 | present: |
876 | /* | |
4aed14e3 BJ |
877 | * Present data to user, advancing rcv_nxt through |
878 | * completed sequence space. | |
2ff61f9d | 879 | */ |
e832edbc | 880 | if (TCPS_HAVERCVDSYN(tp->t_state) == 0) |
4aed14e3 | 881 | return (0); |
2b4b57cd | 882 | ti = tp->seg_next; |
e832edbc BJ |
883 | if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) |
884 | return (0); | |
885 | if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) | |
886 | return (0); | |
887 | do { | |
4aed14e3 BJ |
888 | tp->rcv_nxt += ti->ti_len; |
889 | flags = ti->ti_flags & TH_FIN; | |
2b4b57cd | 890 | remque(ti); |
e832edbc | 891 | m = dtom(ti); |
2b4b57cd | 892 | ti = (struct tcpiphdr *)ti->ti_next; |
e832edbc | 893 | if (so->so_state & SS_CANTRCVMORE) |
668cc26d | 894 | m_freem(m); |
599c842e BJ |
895 | else { |
896 | SBCHECK(&so->so_rcv, "tcp_input before"); | |
e832edbc | 897 | sbappend(&so->so_rcv, m); |
599c842e BJ |
898 | SBCHECK(&so->so_rcv, "tcp_input after"); |
899 | } | |
e832edbc BJ |
900 | } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); |
901 | sorwakeup(so); | |
2ff61f9d BJ |
902 | return (flags); |
903 | drop: | |
904 | m_freem(dtom(ti)); | |
e832edbc | 905 | return (0); |
d52566dd | 906 | } |