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1.1 root 1: /*
2: * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994
3: * The Regents of the University of California. All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
1.1.1.4 root 13: * 3. Neither the name of the University nor the names of its contributors
1.1 root 14: * may be used to endorse or promote products derived from this software
15: * without specific prior written permission.
16: *
17: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27: * SUCH DAMAGE.
28: *
29: * @(#)tcp_input.c 8.5 (Berkeley) 4/10/94
30: * tcp_input.c,v 1.10 1994/10/13 18:36:32 wollman Exp
31: */
32:
33: /*
34: * Changes and additions relating to SLiRP
35: * Copyright (c) 1995 Danny Gasparovski.
1.1.1.3 root 36: *
37: * Please read the file COPYRIGHT for the
1.1 root 38: * terms and conditions of the copyright.
39: */
40:
41: #include <slirp.h>
42: #include "ip_icmp.h"
43:
1.1.1.3 root 44: #define TCPREXMTTHRESH 3
1.1 root 45:
46: #define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * PR_SLOWHZ)
47:
48: /* for modulo comparisons of timestamps */
49: #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0)
50: #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0)
51:
52: /*
53: * Insert segment ti into reassembly queue of tcp with
54: * control block tp. Return TH_FIN if reassembly now includes
55: * a segment with FIN. The macro form does the common case inline
56: * (segment is the next to be received on an established connection,
57: * and the queue is empty), avoiding linkage into and removal
58: * from the queue and repetition of various conversions.
59: * Set DELACK for segments received in order, but ack immediately
60: * when segments are out of order (so fast retransmit can work).
61: */
62: #ifdef TCP_ACK_HACK
63: #define TCP_REASS(tp, ti, m, so, flags) {\
64: if ((ti)->ti_seq == (tp)->rcv_nxt && \
1.1.1.4 root 65: tcpfrag_list_empty(tp) && \
1.1 root 66: (tp)->t_state == TCPS_ESTABLISHED) {\
67: if (ti->ti_flags & TH_PUSH) \
68: tp->t_flags |= TF_ACKNOW; \
69: else \
70: tp->t_flags |= TF_DELACK; \
71: (tp)->rcv_nxt += (ti)->ti_len; \
72: flags = (ti)->ti_flags & TH_FIN; \
73: if (so->so_emu) { \
74: if (tcp_emu((so),(m))) sbappend((so), (m)); \
75: } else \
76: sbappend((so), (m)); \
77: } else {\
78: (flags) = tcp_reass((tp), (ti), (m)); \
79: tp->t_flags |= TF_ACKNOW; \
80: } \
81: }
82: #else
83: #define TCP_REASS(tp, ti, m, so, flags) { \
84: if ((ti)->ti_seq == (tp)->rcv_nxt && \
1.1.1.4 root 85: tcpfrag_list_empty(tp) && \
1.1 root 86: (tp)->t_state == TCPS_ESTABLISHED) { \
87: tp->t_flags |= TF_DELACK; \
88: (tp)->rcv_nxt += (ti)->ti_len; \
89: flags = (ti)->ti_flags & TH_FIN; \
90: if (so->so_emu) { \
91: if (tcp_emu((so),(m))) sbappend(so, (m)); \
92: } else \
93: sbappend((so), (m)); \
94: } else { \
95: (flags) = tcp_reass((tp), (ti), (m)); \
96: tp->t_flags |= TF_ACKNOW; \
97: } \
98: }
99: #endif
1.1.1.3 root 100: static void tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt,
101: struct tcpiphdr *ti);
102: static void tcp_xmit_timer(register struct tcpcb *tp, int rtt);
103:
104: static int
105: tcp_reass(register struct tcpcb *tp, register struct tcpiphdr *ti,
106: struct mbuf *m)
1.1 root 107: {
108: register struct tcpiphdr *q;
109: struct socket *so = tp->t_socket;
110: int flags;
1.1.1.3 root 111:
1.1 root 112: /*
1.1.1.5 root 113: * Call with ti==NULL after become established to
1.1 root 114: * force pre-ESTABLISHED data up to user socket.
115: */
1.1.1.5 root 116: if (ti == NULL)
1.1 root 117: goto present;
118:
119: /*
120: * Find a segment which begins after this one does.
121: */
1.1.1.4 root 122: for (q = tcpfrag_list_first(tp); !tcpfrag_list_end(q, tp);
123: q = tcpiphdr_next(q))
1.1 root 124: if (SEQ_GT(q->ti_seq, ti->ti_seq))
125: break;
126:
127: /*
128: * If there is a preceding segment, it may provide some of
129: * our data already. If so, drop the data from the incoming
130: * segment. If it provides all of our data, drop us.
131: */
1.1.1.4 root 132: if (!tcpfrag_list_end(tcpiphdr_prev(q), tp)) {
1.1 root 133: register int i;
1.1.1.4 root 134: q = tcpiphdr_prev(q);
1.1 root 135: /* conversion to int (in i) handles seq wraparound */
136: i = q->ti_seq + q->ti_len - ti->ti_seq;
137: if (i > 0) {
138: if (i >= ti->ti_len) {
139: m_freem(m);
140: /*
141: * Try to present any queued data
142: * at the left window edge to the user.
143: * This is needed after the 3-WHS
144: * completes.
145: */
146: goto present; /* ??? */
147: }
148: m_adj(m, i);
149: ti->ti_len -= i;
150: ti->ti_seq += i;
151: }
1.1.1.4 root 152: q = tcpiphdr_next(q);
1.1 root 153: }
1.1.1.4 root 154: ti->ti_mbuf = m;
1.1 root 155:
156: /*
157: * While we overlap succeeding segments trim them or,
158: * if they are completely covered, dequeue them.
159: */
1.1.1.4 root 160: while (!tcpfrag_list_end(q, tp)) {
1.1 root 161: register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq;
162: if (i <= 0)
163: break;
164: if (i < q->ti_len) {
165: q->ti_seq += i;
166: q->ti_len -= i;
1.1.1.4 root 167: m_adj(q->ti_mbuf, i);
1.1 root 168: break;
169: }
1.1.1.4 root 170: q = tcpiphdr_next(q);
171: m = tcpiphdr_prev(q)->ti_mbuf;
172: remque(tcpiphdr2qlink(tcpiphdr_prev(q)));
1.1 root 173: m_freem(m);
174: }
175:
176: /*
177: * Stick new segment in its place.
178: */
1.1.1.4 root 179: insque(tcpiphdr2qlink(ti), tcpiphdr2qlink(tcpiphdr_prev(q)));
1.1 root 180:
181: present:
182: /*
183: * Present data to user, advancing rcv_nxt through
184: * completed sequence space.
185: */
186: if (!TCPS_HAVEESTABLISHED(tp->t_state))
187: return (0);
1.1.1.4 root 188: ti = tcpfrag_list_first(tp);
189: if (tcpfrag_list_end(ti, tp) || ti->ti_seq != tp->rcv_nxt)
1.1 root 190: return (0);
191: if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len)
192: return (0);
193: do {
194: tp->rcv_nxt += ti->ti_len;
195: flags = ti->ti_flags & TH_FIN;
1.1.1.4 root 196: remque(tcpiphdr2qlink(ti));
197: m = ti->ti_mbuf;
198: ti = tcpiphdr_next(ti);
1.1 root 199: if (so->so_state & SS_FCANTSENDMORE)
200: m_freem(m);
201: else {
202: if (so->so_emu) {
203: if (tcp_emu(so,m)) sbappend(so, m);
204: } else
205: sbappend(so, m);
206: }
207: } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt);
208: return (flags);
209: }
210:
211: /*
212: * TCP input routine, follows pages 65-76 of the
213: * protocol specification dated September, 1981 very closely.
214: */
215: void
1.1.1.5 root 216: tcp_input(struct mbuf *m, int iphlen, struct socket *inso)
1.1 root 217: {
218: struct ip save_ip, *ip;
219: register struct tcpiphdr *ti;
220: caddr_t optp = NULL;
221: int optlen = 0;
222: int len, tlen, off;
1.1.1.5 root 223: register struct tcpcb *tp = NULL;
1.1 root 224: register int tiflags;
1.1.1.5 root 225: struct socket *so = NULL;
1.1 root 226: int todrop, acked, ourfinisacked, needoutput = 0;
227: int iss = 0;
228: u_long tiwin;
229: int ret;
1.1.1.4 root 230: struct ex_list *ex_ptr;
1.1.1.5 root 231: Slirp *slirp;
1.1 root 232:
233: DEBUG_CALL("tcp_input");
1.1.1.3 root 234: DEBUG_ARGS((dfd," m = %8lx iphlen = %2d inso = %lx\n",
1.1 root 235: (long )m, iphlen, (long )inso ));
1.1.1.3 root 236:
1.1 root 237: /*
238: * If called with m == 0, then we're continuing the connect
239: */
240: if (m == NULL) {
241: so = inso;
1.1.1.5 root 242: slirp = so->slirp;
1.1.1.3 root 243:
1.1 root 244: /* Re-set a few variables */
245: tp = sototcpcb(so);
246: m = so->so_m;
1.1.1.5 root 247: so->so_m = NULL;
1.1 root 248: ti = so->so_ti;
249: tiwin = ti->ti_win;
250: tiflags = ti->ti_flags;
1.1.1.3 root 251:
1.1 root 252: goto cont_conn;
253: }
1.1.1.5 root 254: slirp = m->slirp;
1.1.1.3 root 255:
1.1 root 256: /*
257: * Get IP and TCP header together in first mbuf.
258: * Note: IP leaves IP header in first mbuf.
259: */
260: ti = mtod(m, struct tcpiphdr *);
261: if (iphlen > sizeof(struct ip )) {
262: ip_stripoptions(m, (struct mbuf *)0);
263: iphlen=sizeof(struct ip );
264: }
265: /* XXX Check if too short */
1.1.1.3 root 266:
1.1 root 267:
268: /*
269: * Save a copy of the IP header in case we want restore it
270: * for sending an ICMP error message in response.
271: */
272: ip=mtod(m, struct ip *);
1.1.1.3 root 273: save_ip = *ip;
1.1 root 274: save_ip.ip_len+= iphlen;
275:
276: /*
277: * Checksum extended TCP header and data.
278: */
279: tlen = ((struct ip *)ti)->ip_len;
1.1.1.5 root 280: tcpiphdr2qlink(ti)->next = tcpiphdr2qlink(ti)->prev = NULL;
281: memset(&ti->ti_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr));
1.1 root 282: ti->ti_x1 = 0;
1.1.1.6 ! root 283: ti->ti_len = htons((uint16_t)tlen);
1.1 root 284: len = sizeof(struct ip ) + tlen;
285: if(cksum(m, len)) {
286: goto drop;
287: }
288:
289: /*
290: * Check that TCP offset makes sense,
291: * pull out TCP options and adjust length. XXX
292: */
293: off = ti->ti_off << 2;
294: if (off < sizeof (struct tcphdr) || off > tlen) {
295: goto drop;
296: }
297: tlen -= off;
298: ti->ti_len = tlen;
299: if (off > sizeof (struct tcphdr)) {
300: optlen = off - sizeof (struct tcphdr);
301: optp = mtod(m, caddr_t) + sizeof (struct tcpiphdr);
302: }
303: tiflags = ti->ti_flags;
1.1.1.3 root 304:
1.1 root 305: /*
306: * Convert TCP protocol specific fields to host format.
307: */
308: NTOHL(ti->ti_seq);
309: NTOHL(ti->ti_ack);
310: NTOHS(ti->ti_win);
311: NTOHS(ti->ti_urp);
312:
313: /*
314: * Drop TCP, IP headers and TCP options.
315: */
316: m->m_data += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
317: m->m_len -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
1.1.1.3 root 318:
1.1.1.5 root 319: if (slirp->restricted) {
320: for (ex_ptr = slirp->exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
1.1.1.4 root 321: if (ex_ptr->ex_fport == ti->ti_dport &&
1.1.1.5 root 322: ti->ti_dst.s_addr == ex_ptr->ex_addr.s_addr) {
1.1.1.4 root 323: break;
1.1.1.5 root 324: }
325: }
1.1.1.4 root 326: if (!ex_ptr)
327: goto drop;
328: }
1.1 root 329: /*
330: * Locate pcb for segment.
331: */
332: findso:
1.1.1.5 root 333: so = slirp->tcp_last_so;
1.1 root 334: if (so->so_fport != ti->ti_dport ||
335: so->so_lport != ti->ti_sport ||
336: so->so_laddr.s_addr != ti->ti_src.s_addr ||
337: so->so_faddr.s_addr != ti->ti_dst.s_addr) {
1.1.1.5 root 338: so = solookup(&slirp->tcb, ti->ti_src, ti->ti_sport,
1.1 root 339: ti->ti_dst, ti->ti_dport);
340: if (so)
1.1.1.5 root 341: slirp->tcp_last_so = so;
1.1 root 342: }
343:
344: /*
345: * If the state is CLOSED (i.e., TCB does not exist) then
346: * all data in the incoming segment is discarded.
347: * If the TCB exists but is in CLOSED state, it is embryonic,
348: * but should either do a listen or a connect soon.
349: *
350: * state == CLOSED means we've done socreate() but haven't
1.1.1.3 root 351: * attached it to a protocol yet...
352: *
1.1 root 353: * XXX If a TCB does not exist, and the TH_SYN flag is
354: * the only flag set, then create a session, mark it
355: * as if it was LISTENING, and continue...
356: */
1.1.1.5 root 357: if (so == NULL) {
1.1 root 358: if ((tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) != TH_SYN)
359: goto dropwithreset;
1.1.1.3 root 360:
1.1.1.5 root 361: if ((so = socreate(slirp)) == NULL)
1.1 root 362: goto dropwithreset;
363: if (tcp_attach(so) < 0) {
364: free(so); /* Not sofree (if it failed, it's not insqued) */
365: goto dropwithreset;
366: }
1.1.1.3 root 367:
368: sbreserve(&so->so_snd, TCP_SNDSPACE);
369: sbreserve(&so->so_rcv, TCP_RCVSPACE);
370:
1.1 root 371: so->so_laddr = ti->ti_src;
372: so->so_lport = ti->ti_sport;
373: so->so_faddr = ti->ti_dst;
374: so->so_fport = ti->ti_dport;
1.1.1.3 root 375:
1.1 root 376: if ((so->so_iptos = tcp_tos(so)) == 0)
377: so->so_iptos = ((struct ip *)ti)->ip_tos;
1.1.1.3 root 378:
1.1 root 379: tp = sototcpcb(so);
380: tp->t_state = TCPS_LISTEN;
381: }
1.1.1.3 root 382:
1.1 root 383: /*
384: * If this is a still-connecting socket, this probably
385: * a retransmit of the SYN. Whether it's a retransmit SYN
386: * or something else, we nuke it.
387: */
388: if (so->so_state & SS_ISFCONNECTING)
389: goto drop;
390:
391: tp = sototcpcb(so);
1.1.1.3 root 392:
1.1 root 393: /* XXX Should never fail */
1.1.1.5 root 394: if (tp == NULL)
1.1 root 395: goto dropwithreset;
396: if (tp->t_state == TCPS_CLOSED)
397: goto drop;
1.1.1.3 root 398:
1.1.1.5 root 399: tiwin = ti->ti_win;
1.1 root 400:
401: /*
402: * Segment received on connection.
403: * Reset idle time and keep-alive timer.
404: */
405: tp->t_idle = 0;
1.1.1.3 root 406: if (SO_OPTIONS)
407: tp->t_timer[TCPT_KEEP] = TCPTV_KEEPINTVL;
1.1 root 408: else
1.1.1.3 root 409: tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_IDLE;
1.1 root 410:
411: /*
412: * Process options if not in LISTEN state,
413: * else do it below (after getting remote address).
414: */
415: if (optp && tp->t_state != TCPS_LISTEN)
1.1.1.3 root 416: tcp_dooptions(tp, (u_char *)optp, optlen, ti);
1.1 root 417:
1.1.1.3 root 418: /*
1.1 root 419: * Header prediction: check for the two common cases
420: * of a uni-directional data xfer. If the packet has
421: * no control flags, is in-sequence, the window didn't
422: * change and we're not retransmitting, it's a
423: * candidate. If the length is zero and the ack moved
424: * forward, we're the sender side of the xfer. Just
425: * free the data acked & wake any higher level process
426: * that was blocked waiting for space. If the length
427: * is non-zero and the ack didn't move, we're the
428: * receiver side. If we're getting packets in-order
429: * (the reassembly queue is empty), add the data to
430: * the socket buffer and note that we need a delayed ack.
431: *
432: * XXX Some of these tests are not needed
433: * eg: the tiwin == tp->snd_wnd prevents many more
434: * predictions.. with no *real* advantage..
435: */
436: if (tp->t_state == TCPS_ESTABLISHED &&
437: (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK &&
438: ti->ti_seq == tp->rcv_nxt &&
439: tiwin && tiwin == tp->snd_wnd &&
440: tp->snd_nxt == tp->snd_max) {
441: if (ti->ti_len == 0) {
442: if (SEQ_GT(ti->ti_ack, tp->snd_una) &&
443: SEQ_LEQ(ti->ti_ack, tp->snd_max) &&
444: tp->snd_cwnd >= tp->snd_wnd) {
445: /*
446: * this is a pure ack for outstanding data.
447: */
1.1.1.5 root 448: if (tp->t_rtt &&
449: SEQ_GT(ti->ti_ack, tp->t_rtseq))
1.1 root 450: tcp_xmit_timer(tp, tp->t_rtt);
451: acked = ti->ti_ack - tp->snd_una;
452: sbdrop(&so->so_snd, acked);
453: tp->snd_una = ti->ti_ack;
454: m_freem(m);
455:
456: /*
457: * If all outstanding data are acked, stop
458: * retransmit timer, otherwise restart timer
459: * using current (possibly backed-off) value.
460: * If process is waiting for space,
461: * wakeup/selwakeup/signal. If data
462: * are ready to send, let tcp_output
463: * decide between more output or persist.
464: */
465: if (tp->snd_una == tp->snd_max)
466: tp->t_timer[TCPT_REXMT] = 0;
467: else if (tp->t_timer[TCPT_PERSIST] == 0)
468: tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
469:
1.1.1.3 root 470: /*
1.1 root 471: * This is called because sowwakeup might have
472: * put data into so_snd. Since we don't so sowwakeup,
473: * we don't need this.. XXX???
474: */
475: if (so->so_snd.sb_cc)
476: (void) tcp_output(tp);
477:
478: return;
479: }
480: } else if (ti->ti_ack == tp->snd_una &&
1.1.1.4 root 481: tcpfrag_list_empty(tp) &&
1.1 root 482: ti->ti_len <= sbspace(&so->so_rcv)) {
483: /*
484: * this is a pure, in-sequence data packet
485: * with nothing on the reassembly queue and
486: * we have enough buffer space to take it.
487: */
488: tp->rcv_nxt += ti->ti_len;
489: /*
490: * Add data to socket buffer.
491: */
492: if (so->so_emu) {
493: if (tcp_emu(so,m)) sbappend(so, m);
494: } else
495: sbappend(so, m);
1.1.1.3 root 496:
497: /*
1.1 root 498: * If this is a short packet, then ACK now - with Nagel
499: * congestion avoidance sender won't send more until
500: * he gets an ACK.
1.1.1.3 root 501: *
1.1.1.2 root 502: * It is better to not delay acks at all to maximize
503: * TCP throughput. See RFC 2581.
1.1.1.3 root 504: */
1.1.1.2 root 505: tp->t_flags |= TF_ACKNOW;
506: tcp_output(tp);
1.1 root 507: return;
508: }
509: } /* header prediction */
510: /*
511: * Calculate amount of space in receive window,
512: * and then do TCP input processing.
513: * Receive window is amount of space in rcv queue,
514: * but not less than advertised window.
515: */
516: { int win;
517: win = sbspace(&so->so_rcv);
518: if (win < 0)
519: win = 0;
520: tp->rcv_wnd = max(win, (int)(tp->rcv_adv - tp->rcv_nxt));
521: }
522:
523: switch (tp->t_state) {
524:
525: /*
526: * If the state is LISTEN then ignore segment if it contains an RST.
527: * If the segment contains an ACK then it is bad and send a RST.
528: * If it does not contain a SYN then it is not interesting; drop it.
529: * Don't bother responding if the destination was a broadcast.
530: * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial
531: * tp->iss, and send a segment:
532: * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
533: * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss.
534: * Fill in remote peer address fields if not previously specified.
535: * Enter SYN_RECEIVED state, and process any other fields of this
536: * segment in this state.
537: */
538: case TCPS_LISTEN: {
539:
540: if (tiflags & TH_RST)
541: goto drop;
542: if (tiflags & TH_ACK)
543: goto dropwithreset;
544: if ((tiflags & TH_SYN) == 0)
545: goto drop;
1.1.1.3 root 546:
1.1 root 547: /*
548: * This has way too many gotos...
549: * But a bit of spaghetti code never hurt anybody :)
550: */
1.1.1.3 root 551:
1.1 root 552: /*
553: * If this is destined for the control address, then flag to
554: * tcp_ctl once connected, otherwise connect
555: */
1.1.1.5 root 556: if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
557: slirp->vnetwork_addr.s_addr) {
558: if (so->so_faddr.s_addr != slirp->vhost_addr.s_addr &&
559: so->so_faddr.s_addr != slirp->vnameserver_addr.s_addr) {
1.1 root 560: /* May be an add exec */
1.1.1.5 root 561: for (ex_ptr = slirp->exec_list; ex_ptr;
562: ex_ptr = ex_ptr->ex_next) {
1.1.1.3 root 563: if(ex_ptr->ex_fport == so->so_fport &&
1.1.1.5 root 564: so->so_faddr.s_addr == ex_ptr->ex_addr.s_addr) {
1.1 root 565: so->so_state |= SS_CTL;
566: break;
567: }
568: }
1.1.1.5 root 569: if (so->so_state & SS_CTL) {
570: goto cont_input;
571: }
1.1 root 572: }
573: /* CTL_ALIAS: Do nothing, tcp_fconnect will be called on it */
574: }
1.1.1.3 root 575:
1.1 root 576: if (so->so_emu & EMU_NOCONNECT) {
577: so->so_emu &= ~EMU_NOCONNECT;
578: goto cont_input;
579: }
1.1.1.3 root 580:
1.1 root 581: if((tcp_fconnect(so) == -1) && (errno != EINPROGRESS) && (errno != EWOULDBLOCK)) {
582: u_char code=ICMP_UNREACH_NET;
583: DEBUG_MISC((dfd," tcp fconnect errno = %d-%s\n",
584: errno,strerror(errno)));
585: if(errno == ECONNREFUSED) {
586: /* ACK the SYN, send RST to refuse the connection */
587: tcp_respond(tp, ti, m, ti->ti_seq+1, (tcp_seq)0,
1.1.1.3 root 588: TH_RST|TH_ACK);
1.1 root 589: } else {
590: if(errno == EHOSTUNREACH) code=ICMP_UNREACH_HOST;
591: HTONL(ti->ti_seq); /* restore tcp header */
592: HTONL(ti->ti_ack);
593: HTONS(ti->ti_win);
594: HTONS(ti->ti_urp);
595: m->m_data -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
596: m->m_len += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
597: *ip=save_ip;
598: icmp_error(m, ICMP_UNREACH,code, 0,strerror(errno));
599: }
1.1.1.6 ! root 600: tcp_close(tp);
1.1 root 601: m_free(m);
602: } else {
603: /*
604: * Haven't connected yet, save the current mbuf
605: * and ti, and return
606: * XXX Some OS's don't tell us whether the connect()
607: * succeeded or not. So we must time it out.
608: */
609: so->so_m = m;
610: so->so_ti = ti;
611: tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
612: tp->t_state = TCPS_SYN_RECEIVED;
613: }
614: return;
615:
1.1.1.3 root 616: cont_conn:
617: /* m==NULL
1.1 root 618: * Check if the connect succeeded
619: */
620: if (so->so_state & SS_NOFDREF) {
621: tp = tcp_close(tp);
622: goto dropwithreset;
623: }
1.1.1.3 root 624: cont_input:
1.1 root 625: tcp_template(tp);
1.1.1.3 root 626:
1.1 root 627: if (optp)
628: tcp_dooptions(tp, (u_char *)optp, optlen, ti);
1.1.1.3 root 629:
1.1 root 630: if (iss)
631: tp->iss = iss;
1.1.1.3 root 632: else
1.1.1.5 root 633: tp->iss = slirp->tcp_iss;
634: slirp->tcp_iss += TCP_ISSINCR/2;
1.1 root 635: tp->irs = ti->ti_seq;
636: tcp_sendseqinit(tp);
637: tcp_rcvseqinit(tp);
638: tp->t_flags |= TF_ACKNOW;
639: tp->t_state = TCPS_SYN_RECEIVED;
640: tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
641: goto trimthenstep6;
642: } /* case TCPS_LISTEN */
1.1.1.3 root 643:
1.1 root 644: /*
645: * If the state is SYN_SENT:
646: * if seg contains an ACK, but not for our SYN, drop the input.
647: * if seg contains a RST, then drop the connection.
648: * if seg does not contain SYN, then drop it.
649: * Otherwise this is an acceptable SYN segment
650: * initialize tp->rcv_nxt and tp->irs
651: * if seg contains ack then advance tp->snd_una
652: * if SYN has been acked change to ESTABLISHED else SYN_RCVD state
653: * arrange for segment to be acked (eventually)
654: * continue processing rest of data/controls, beginning with URG
655: */
656: case TCPS_SYN_SENT:
657: if ((tiflags & TH_ACK) &&
658: (SEQ_LEQ(ti->ti_ack, tp->iss) ||
659: SEQ_GT(ti->ti_ack, tp->snd_max)))
660: goto dropwithreset;
661:
662: if (tiflags & TH_RST) {
1.1.1.6 ! root 663: if (tiflags & TH_ACK) {
! 664: tcp_drop(tp, 0); /* XXX Check t_softerror! */
! 665: }
1.1 root 666: goto drop;
667: }
668:
669: if ((tiflags & TH_SYN) == 0)
670: goto drop;
671: if (tiflags & TH_ACK) {
672: tp->snd_una = ti->ti_ack;
673: if (SEQ_LT(tp->snd_nxt, tp->snd_una))
674: tp->snd_nxt = tp->snd_una;
675: }
676:
677: tp->t_timer[TCPT_REXMT] = 0;
678: tp->irs = ti->ti_seq;
679: tcp_rcvseqinit(tp);
680: tp->t_flags |= TF_ACKNOW;
681: if (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) {
682: soisfconnected(so);
683: tp->t_state = TCPS_ESTABLISHED;
1.1.1.3 root 684:
1.1 root 685: (void) tcp_reass(tp, (struct tcpiphdr *)0,
686: (struct mbuf *)0);
687: /*
688: * if we didn't have to retransmit the SYN,
689: * use its rtt as our initial srtt & rtt var.
690: */
691: if (tp->t_rtt)
692: tcp_xmit_timer(tp, tp->t_rtt);
693: } else
694: tp->t_state = TCPS_SYN_RECEIVED;
695:
696: trimthenstep6:
697: /*
698: * Advance ti->ti_seq to correspond to first data byte.
699: * If data, trim to stay within window,
700: * dropping FIN if necessary.
701: */
702: ti->ti_seq++;
703: if (ti->ti_len > tp->rcv_wnd) {
704: todrop = ti->ti_len - tp->rcv_wnd;
705: m_adj(m, -todrop);
706: ti->ti_len = tp->rcv_wnd;
707: tiflags &= ~TH_FIN;
708: }
709: tp->snd_wl1 = ti->ti_seq - 1;
710: tp->rcv_up = ti->ti_seq;
711: goto step6;
712: } /* switch tp->t_state */
713: /*
714: * States other than LISTEN or SYN_SENT.
1.1.1.5 root 715: * Check that at least some bytes of segment are within
1.1 root 716: * receive window. If segment begins before rcv_nxt,
717: * drop leading data (and SYN); if nothing left, just ack.
718: */
719: todrop = tp->rcv_nxt - ti->ti_seq;
720: if (todrop > 0) {
721: if (tiflags & TH_SYN) {
722: tiflags &= ~TH_SYN;
723: ti->ti_seq++;
1.1.1.3 root 724: if (ti->ti_urp > 1)
1.1 root 725: ti->ti_urp--;
726: else
727: tiflags &= ~TH_URG;
728: todrop--;
729: }
730: /*
731: * Following if statement from Stevens, vol. 2, p. 960.
732: */
733: if (todrop > ti->ti_len
734: || (todrop == ti->ti_len && (tiflags & TH_FIN) == 0)) {
735: /*
736: * Any valid FIN must be to the left of the window.
737: * At this point the FIN must be a duplicate or out
738: * of sequence; drop it.
739: */
740: tiflags &= ~TH_FIN;
1.1.1.3 root 741:
1.1 root 742: /*
743: * Send an ACK to resynchronize and drop any data.
744: * But keep on processing for RST or ACK.
745: */
746: tp->t_flags |= TF_ACKNOW;
747: todrop = ti->ti_len;
748: }
749: m_adj(m, todrop);
750: ti->ti_seq += todrop;
751: ti->ti_len -= todrop;
752: if (ti->ti_urp > todrop)
753: ti->ti_urp -= todrop;
754: else {
755: tiflags &= ~TH_URG;
756: ti->ti_urp = 0;
757: }
758: }
759: /*
760: * If new data are received on a connection after the
761: * user processes are gone, then RST the other end.
762: */
763: if ((so->so_state & SS_NOFDREF) &&
764: tp->t_state > TCPS_CLOSE_WAIT && ti->ti_len) {
765: tp = tcp_close(tp);
766: goto dropwithreset;
767: }
768:
769: /*
770: * If segment ends after window, drop trailing data
771: * (and PUSH and FIN); if nothing left, just ACK.
772: */
773: todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd);
774: if (todrop > 0) {
775: if (todrop >= ti->ti_len) {
776: /*
777: * If a new connection request is received
778: * while in TIME_WAIT, drop the old connection
779: * and start over if the sequence numbers
780: * are above the previous ones.
781: */
782: if (tiflags & TH_SYN &&
783: tp->t_state == TCPS_TIME_WAIT &&
784: SEQ_GT(ti->ti_seq, tp->rcv_nxt)) {
785: iss = tp->rcv_nxt + TCP_ISSINCR;
786: tp = tcp_close(tp);
787: goto findso;
788: }
789: /*
790: * If window is closed can only take segments at
791: * window edge, and have to drop data and PUSH from
792: * incoming segments. Continue processing, but
793: * remember to ack. Otherwise, drop segment
794: * and ack.
795: */
796: if (tp->rcv_wnd == 0 && ti->ti_seq == tp->rcv_nxt) {
797: tp->t_flags |= TF_ACKNOW;
1.1.1.5 root 798: } else {
1.1 root 799: goto dropafterack;
1.1.1.5 root 800: }
801: }
1.1 root 802: m_adj(m, -todrop);
803: ti->ti_len -= todrop;
804: tiflags &= ~(TH_PUSH|TH_FIN);
805: }
806:
807: /*
808: * If the RST bit is set examine the state:
809: * SYN_RECEIVED STATE:
810: * If passive open, return to LISTEN state.
811: * If active open, inform user that connection was refused.
812: * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES:
813: * Inform user that connection was reset, and close tcb.
814: * CLOSING, LAST_ACK, TIME_WAIT STATES
815: * Close the tcb.
816: */
817: if (tiflags&TH_RST) switch (tp->t_state) {
818:
819: case TCPS_SYN_RECEIVED:
820: case TCPS_ESTABLISHED:
821: case TCPS_FIN_WAIT_1:
822: case TCPS_FIN_WAIT_2:
823: case TCPS_CLOSE_WAIT:
824: tp->t_state = TCPS_CLOSED;
1.1.1.6 ! root 825: tcp_close(tp);
1.1 root 826: goto drop;
827:
828: case TCPS_CLOSING:
829: case TCPS_LAST_ACK:
830: case TCPS_TIME_WAIT:
1.1.1.6 ! root 831: tcp_close(tp);
1.1 root 832: goto drop;
833: }
834:
835: /*
836: * If a SYN is in the window, then this is an
837: * error and we send an RST and drop the connection.
838: */
839: if (tiflags & TH_SYN) {
840: tp = tcp_drop(tp,0);
841: goto dropwithreset;
842: }
843:
844: /*
845: * If the ACK bit is off we drop the segment and return.
846: */
847: if ((tiflags & TH_ACK) == 0) goto drop;
848:
849: /*
850: * Ack processing.
851: */
852: switch (tp->t_state) {
853: /*
854: * In SYN_RECEIVED state if the ack ACKs our SYN then enter
855: * ESTABLISHED state and continue processing, otherwise
856: * send an RST. una<=ack<=max
857: */
858: case TCPS_SYN_RECEIVED:
859:
860: if (SEQ_GT(tp->snd_una, ti->ti_ack) ||
861: SEQ_GT(ti->ti_ack, tp->snd_max))
862: goto dropwithreset;
863: tp->t_state = TCPS_ESTABLISHED;
1.1.1.3 root 864: /*
865: * The sent SYN is ack'ed with our sequence number +1
866: * The first data byte already in the buffer will get
1.1 root 867: * lost if no correction is made. This is only needed for
868: * SS_CTL since the buffer is empty otherwise.
1.1.1.3 root 869: * tp->snd_una++; or:
1.1 root 870: */
871: tp->snd_una=ti->ti_ack;
872: if (so->so_state & SS_CTL) {
873: /* So tcp_ctl reports the right state */
874: ret = tcp_ctl(so);
875: if (ret == 1) {
876: soisfconnected(so);
877: so->so_state &= ~SS_CTL; /* success XXX */
878: } else if (ret == 2) {
1.1.1.5 root 879: so->so_state &= SS_PERSISTENT_MASK;
880: so->so_state |= SS_NOFDREF; /* CTL_CMD */
1.1 root 881: } else {
882: needoutput = 1;
883: tp->t_state = TCPS_FIN_WAIT_1;
884: }
885: } else {
886: soisfconnected(so);
887: }
1.1.1.3 root 888:
1.1 root 889: (void) tcp_reass(tp, (struct tcpiphdr *)0, (struct mbuf *)0);
890: tp->snd_wl1 = ti->ti_seq - 1;
891: /* Avoid ack processing; snd_una==ti_ack => dup ack */
892: goto synrx_to_est;
893: /* fall into ... */
894:
895: /*
896: * In ESTABLISHED state: drop duplicate ACKs; ACK out of range
897: * ACKs. If the ack is in the range
898: * tp->snd_una < ti->ti_ack <= tp->snd_max
899: * then advance tp->snd_una to ti->ti_ack and drop
900: * data from the retransmission queue. If this ACK reflects
901: * more up to date window information we update our window information.
902: */
903: case TCPS_ESTABLISHED:
904: case TCPS_FIN_WAIT_1:
905: case TCPS_FIN_WAIT_2:
906: case TCPS_CLOSE_WAIT:
907: case TCPS_CLOSING:
908: case TCPS_LAST_ACK:
909: case TCPS_TIME_WAIT:
910:
911: if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) {
912: if (ti->ti_len == 0 && tiwin == tp->snd_wnd) {
913: DEBUG_MISC((dfd," dup ack m = %lx so = %lx \n",
914: (long )m, (long )so));
915: /*
916: * If we have outstanding data (other than
917: * a window probe), this is a completely
918: * duplicate ack (ie, window info didn't
919: * change), the ack is the biggest we've
920: * seen and we've seen exactly our rexmt
921: * threshold of them, assume a packet
922: * has been dropped and retransmit it.
923: * Kludge snd_nxt & the congestion
924: * window so we send only this one
925: * packet.
926: *
927: * We know we're losing at the current
928: * window size so do congestion avoidance
929: * (set ssthresh to half the current window
930: * and pull our congestion window back to
931: * the new ssthresh).
932: *
933: * Dup acks mean that packets have left the
1.1.1.3 root 934: * network (they're now cached at the receiver)
1.1 root 935: * so bump cwnd by the amount in the receiver
936: * to keep a constant cwnd packets in the
937: * network.
938: */
939: if (tp->t_timer[TCPT_REXMT] == 0 ||
940: ti->ti_ack != tp->snd_una)
941: tp->t_dupacks = 0;
1.1.1.3 root 942: else if (++tp->t_dupacks == TCPREXMTTHRESH) {
1.1 root 943: tcp_seq onxt = tp->snd_nxt;
944: u_int win =
945: min(tp->snd_wnd, tp->snd_cwnd) / 2 /
946: tp->t_maxseg;
947:
948: if (win < 2)
949: win = 2;
950: tp->snd_ssthresh = win * tp->t_maxseg;
951: tp->t_timer[TCPT_REXMT] = 0;
952: tp->t_rtt = 0;
953: tp->snd_nxt = ti->ti_ack;
954: tp->snd_cwnd = tp->t_maxseg;
955: (void) tcp_output(tp);
956: tp->snd_cwnd = tp->snd_ssthresh +
957: tp->t_maxseg * tp->t_dupacks;
958: if (SEQ_GT(onxt, tp->snd_nxt))
959: tp->snd_nxt = onxt;
960: goto drop;
1.1.1.3 root 961: } else if (tp->t_dupacks > TCPREXMTTHRESH) {
1.1 root 962: tp->snd_cwnd += tp->t_maxseg;
963: (void) tcp_output(tp);
964: goto drop;
965: }
966: } else
967: tp->t_dupacks = 0;
968: break;
969: }
970: synrx_to_est:
971: /*
972: * If the congestion window was inflated to account
973: * for the other side's cached packets, retract it.
974: */
1.1.1.3 root 975: if (tp->t_dupacks > TCPREXMTTHRESH &&
1.1 root 976: tp->snd_cwnd > tp->snd_ssthresh)
977: tp->snd_cwnd = tp->snd_ssthresh;
978: tp->t_dupacks = 0;
979: if (SEQ_GT(ti->ti_ack, tp->snd_max)) {
980: goto dropafterack;
981: }
982: acked = ti->ti_ack - tp->snd_una;
983:
984: /*
1.1.1.5 root 985: * If transmit timer is running and timed sequence
1.1 root 986: * number was acked, update smoothed round trip time.
987: * Since we now have an rtt measurement, cancel the
988: * timer backoff (cf., Phil Karn's retransmit alg.).
989: * Recompute the initial retransmit timer.
990: */
1.1.1.5 root 991: if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq))
1.1 root 992: tcp_xmit_timer(tp,tp->t_rtt);
993:
994: /*
995: * If all outstanding data is acked, stop retransmit
996: * timer and remember to restart (more output or persist).
997: * If there is more data to be acked, restart retransmit
998: * timer, using current (possibly backed-off) value.
999: */
1000: if (ti->ti_ack == tp->snd_max) {
1001: tp->t_timer[TCPT_REXMT] = 0;
1002: needoutput = 1;
1003: } else if (tp->t_timer[TCPT_PERSIST] == 0)
1004: tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
1005: /*
1006: * When new data is acked, open the congestion window.
1007: * If the window gives us less than ssthresh packets
1008: * in flight, open exponentially (maxseg per packet).
1009: * Otherwise open linearly: maxseg per window
1010: * (maxseg^2 / cwnd per packet).
1011: */
1012: {
1013: register u_int cw = tp->snd_cwnd;
1014: register u_int incr = tp->t_maxseg;
1015:
1016: if (cw > tp->snd_ssthresh)
1017: incr = incr * incr / cw;
1018: tp->snd_cwnd = min(cw + incr, TCP_MAXWIN<<tp->snd_scale);
1019: }
1020: if (acked > so->so_snd.sb_cc) {
1021: tp->snd_wnd -= so->so_snd.sb_cc;
1022: sbdrop(&so->so_snd, (int )so->so_snd.sb_cc);
1023: ourfinisacked = 1;
1024: } else {
1025: sbdrop(&so->so_snd, acked);
1026: tp->snd_wnd -= acked;
1027: ourfinisacked = 0;
1028: }
1029: tp->snd_una = ti->ti_ack;
1030: if (SEQ_LT(tp->snd_nxt, tp->snd_una))
1031: tp->snd_nxt = tp->snd_una;
1032:
1033: switch (tp->t_state) {
1034:
1035: /*
1036: * In FIN_WAIT_1 STATE in addition to the processing
1037: * for the ESTABLISHED state if our FIN is now acknowledged
1038: * then enter FIN_WAIT_2.
1039: */
1040: case TCPS_FIN_WAIT_1:
1041: if (ourfinisacked) {
1042: /*
1043: * If we can't receive any more
1044: * data, then closing user can proceed.
1045: * Starting the timer is contrary to the
1046: * specification, but if we don't get a FIN
1047: * we'll hang forever.
1048: */
1049: if (so->so_state & SS_FCANTRCVMORE) {
1.1.1.3 root 1050: tp->t_timer[TCPT_2MSL] = TCP_MAXIDLE;
1.1 root 1051: }
1052: tp->t_state = TCPS_FIN_WAIT_2;
1053: }
1054: break;
1055:
1056: /*
1057: * In CLOSING STATE in addition to the processing for
1058: * the ESTABLISHED state if the ACK acknowledges our FIN
1059: * then enter the TIME-WAIT state, otherwise ignore
1060: * the segment.
1061: */
1062: case TCPS_CLOSING:
1063: if (ourfinisacked) {
1064: tp->t_state = TCPS_TIME_WAIT;
1065: tcp_canceltimers(tp);
1066: tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1067: }
1068: break;
1069:
1070: /*
1071: * In LAST_ACK, we may still be waiting for data to drain
1072: * and/or to be acked, as well as for the ack of our FIN.
1073: * If our FIN is now acknowledged, delete the TCB,
1074: * enter the closed state and return.
1075: */
1076: case TCPS_LAST_ACK:
1077: if (ourfinisacked) {
1.1.1.6 ! root 1078: tcp_close(tp);
1.1 root 1079: goto drop;
1080: }
1081: break;
1082:
1083: /*
1084: * In TIME_WAIT state the only thing that should arrive
1085: * is a retransmission of the remote FIN. Acknowledge
1086: * it and restart the finack timer.
1087: */
1088: case TCPS_TIME_WAIT:
1089: tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1090: goto dropafterack;
1091: }
1092: } /* switch(tp->t_state) */
1093:
1094: step6:
1095: /*
1096: * Update window information.
1097: * Don't look at window if no ACK: TAC's send garbage on first SYN.
1098: */
1099: if ((tiflags & TH_ACK) &&
1.1.1.3 root 1100: (SEQ_LT(tp->snd_wl1, ti->ti_seq) ||
1.1 root 1101: (tp->snd_wl1 == ti->ti_seq && (SEQ_LT(tp->snd_wl2, ti->ti_ack) ||
1102: (tp->snd_wl2 == ti->ti_ack && tiwin > tp->snd_wnd))))) {
1103: tp->snd_wnd = tiwin;
1104: tp->snd_wl1 = ti->ti_seq;
1105: tp->snd_wl2 = ti->ti_ack;
1106: if (tp->snd_wnd > tp->max_sndwnd)
1107: tp->max_sndwnd = tp->snd_wnd;
1108: needoutput = 1;
1109: }
1110:
1111: /*
1112: * Process segments with URG.
1113: */
1114: if ((tiflags & TH_URG) && ti->ti_urp &&
1115: TCPS_HAVERCVDFIN(tp->t_state) == 0) {
1116: /*
1117: * This is a kludge, but if we receive and accept
1118: * random urgent pointers, we'll crash in
1119: * soreceive. It's hard to imagine someone
1120: * actually wanting to send this much urgent data.
1121: */
1122: if (ti->ti_urp + so->so_rcv.sb_cc > so->so_rcv.sb_datalen) {
1123: ti->ti_urp = 0;
1124: tiflags &= ~TH_URG;
1125: goto dodata;
1126: }
1127: /*
1128: * If this segment advances the known urgent pointer,
1129: * then mark the data stream. This should not happen
1130: * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
1.1.1.3 root 1131: * a FIN has been received from the remote side.
1.1 root 1132: * In these states we ignore the URG.
1133: *
1134: * According to RFC961 (Assigned Protocols),
1135: * the urgent pointer points to the last octet
1136: * of urgent data. We continue, however,
1137: * to consider it to indicate the first octet
1.1.1.3 root 1138: * of data past the urgent section as the original
1.1 root 1139: * spec states (in one of two places).
1140: */
1141: if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) {
1142: tp->rcv_up = ti->ti_seq + ti->ti_urp;
1143: so->so_urgc = so->so_rcv.sb_cc +
1144: (tp->rcv_up - tp->rcv_nxt); /* -1; */
1145: tp->rcv_up = ti->ti_seq + ti->ti_urp;
1.1.1.3 root 1146:
1.1 root 1147: }
1148: } else
1149: /*
1150: * If no out of band data is expected,
1151: * pull receive urgent pointer along
1152: * with the receive window.
1153: */
1154: if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
1155: tp->rcv_up = tp->rcv_nxt;
1156: dodata:
1157:
1158: /*
1159: * Process the segment text, merging it into the TCP sequencing queue,
1160: * and arranging for acknowledgment of receipt if necessary.
1161: * This process logically involves adjusting tp->rcv_wnd as data
1162: * is presented to the user (this happens in tcp_usrreq.c,
1163: * case PRU_RCVD). If a FIN has already been received on this
1164: * connection then we just ignore the text.
1165: */
1166: if ((ti->ti_len || (tiflags&TH_FIN)) &&
1167: TCPS_HAVERCVDFIN(tp->t_state) == 0) {
1168: TCP_REASS(tp, ti, m, so, tiflags);
1169: } else {
1170: m_free(m);
1171: tiflags &= ~TH_FIN;
1172: }
1173:
1174: /*
1175: * If FIN is received ACK the FIN and let the user know
1176: * that the connection is closing.
1177: */
1178: if (tiflags & TH_FIN) {
1179: if (TCPS_HAVERCVDFIN(tp->t_state) == 0) {
1180: /*
1181: * If we receive a FIN we can't send more data,
1182: * set it SS_FDRAIN
1183: * Shutdown the socket if there is no rx data in the
1184: * buffer.
1185: * soread() is called on completion of shutdown() and
1186: * will got to TCPS_LAST_ACK, and use tcp_output()
1187: * to send the FIN.
1188: */
1189: sofwdrain(so);
1.1.1.3 root 1190:
1.1 root 1191: tp->t_flags |= TF_ACKNOW;
1192: tp->rcv_nxt++;
1193: }
1194: switch (tp->t_state) {
1195:
1196: /*
1197: * In SYN_RECEIVED and ESTABLISHED STATES
1198: * enter the CLOSE_WAIT state.
1199: */
1200: case TCPS_SYN_RECEIVED:
1201: case TCPS_ESTABLISHED:
1202: if(so->so_emu == EMU_CTL) /* no shutdown on socket */
1203: tp->t_state = TCPS_LAST_ACK;
1.1.1.3 root 1204: else
1.1 root 1205: tp->t_state = TCPS_CLOSE_WAIT;
1206: break;
1207:
1208: /*
1209: * If still in FIN_WAIT_1 STATE FIN has not been acked so
1210: * enter the CLOSING state.
1211: */
1212: case TCPS_FIN_WAIT_1:
1213: tp->t_state = TCPS_CLOSING;
1214: break;
1215:
1216: /*
1217: * In FIN_WAIT_2 state enter the TIME_WAIT state,
1.1.1.3 root 1218: * starting the time-wait timer, turning off the other
1.1 root 1219: * standard timers.
1220: */
1221: case TCPS_FIN_WAIT_2:
1222: tp->t_state = TCPS_TIME_WAIT;
1223: tcp_canceltimers(tp);
1224: tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1225: break;
1226:
1227: /*
1228: * In TIME_WAIT state restart the 2 MSL time_wait timer.
1229: */
1230: case TCPS_TIME_WAIT:
1231: tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1232: break;
1233: }
1234: }
1235:
1236: /*
1237: * If this is a small packet, then ACK now - with Nagel
1238: * congestion avoidance sender won't send more until
1239: * he gets an ACK.
1.1.1.3 root 1240: *
1.1 root 1241: * See above.
1242: */
1243: if (ti->ti_len && (unsigned)ti->ti_len <= 5 &&
1244: ((struct tcpiphdr_2 *)ti)->first_char == (char)27) {
1245: tp->t_flags |= TF_ACKNOW;
1246: }
1247:
1248: /*
1249: * Return any desired output.
1250: */
1251: if (needoutput || (tp->t_flags & TF_ACKNOW)) {
1252: (void) tcp_output(tp);
1253: }
1254: return;
1255:
1256: dropafterack:
1257: /*
1258: * Generate an ACK dropping incoming segment if it occupies
1259: * sequence space, where the ACK reflects our state.
1260: */
1261: if (tiflags & TH_RST)
1262: goto drop;
1263: m_freem(m);
1264: tp->t_flags |= TF_ACKNOW;
1265: (void) tcp_output(tp);
1266: return;
1267:
1268: dropwithreset:
1269: /* reuses m if m!=NULL, m_free() unnecessary */
1270: if (tiflags & TH_ACK)
1271: tcp_respond(tp, ti, m, (tcp_seq)0, ti->ti_ack, TH_RST);
1272: else {
1273: if (tiflags & TH_SYN) ti->ti_len++;
1274: tcp_respond(tp, ti, m, ti->ti_seq+ti->ti_len, (tcp_seq)0,
1275: TH_RST|TH_ACK);
1276: }
1277:
1278: return;
1279:
1280: drop:
1281: /*
1282: * Drop space held by incoming segment and return.
1283: */
1284: m_free(m);
1285:
1286: return;
1287: }
1288:
1.1.1.3 root 1289: static void
1290: tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt, struct tcpiphdr *ti)
1.1 root 1291: {
1.1.1.6 ! root 1292: uint16_t mss;
1.1 root 1293: int opt, optlen;
1294:
1295: DEBUG_CALL("tcp_dooptions");
1296: DEBUG_ARGS((dfd," tp = %lx cnt=%i \n", (long )tp, cnt));
1297:
1298: for (; cnt > 0; cnt -= optlen, cp += optlen) {
1299: opt = cp[0];
1300: if (opt == TCPOPT_EOL)
1301: break;
1302: if (opt == TCPOPT_NOP)
1303: optlen = 1;
1304: else {
1305: optlen = cp[1];
1306: if (optlen <= 0)
1307: break;
1308: }
1309: switch (opt) {
1310:
1311: default:
1312: continue;
1313:
1314: case TCPOPT_MAXSEG:
1315: if (optlen != TCPOLEN_MAXSEG)
1316: continue;
1317: if (!(ti->ti_flags & TH_SYN))
1318: continue;
1319: memcpy((char *) &mss, (char *) cp + 2, sizeof(mss));
1320: NTOHS(mss);
1321: (void) tcp_mss(tp, mss); /* sets t_maxseg */
1322: break;
1323: }
1324: }
1325: }
1326:
1327:
1328: /*
1329: * Pull out of band byte out of a segment so
1330: * it doesn't appear in the user's data queue.
1331: * It is still reflected in the segment length for
1332: * sequencing purposes.
1333: */
1334:
1335: #ifdef notdef
1336:
1337: void
1338: tcp_pulloutofband(so, ti, m)
1339: struct socket *so;
1340: struct tcpiphdr *ti;
1341: register struct mbuf *m;
1342: {
1343: int cnt = ti->ti_urp - 1;
1.1.1.3 root 1344:
1.1 root 1345: while (cnt >= 0) {
1346: if (m->m_len > cnt) {
1347: char *cp = mtod(m, caddr_t) + cnt;
1348: struct tcpcb *tp = sototcpcb(so);
1349:
1350: tp->t_iobc = *cp;
1351: tp->t_oobflags |= TCPOOB_HAVEDATA;
1352: memcpy(sp, cp+1, (unsigned)(m->m_len - cnt - 1));
1353: m->m_len--;
1354: return;
1355: }
1356: cnt -= m->m_len;
1357: m = m->m_next; /* XXX WRONG! Fix it! */
1358: if (m == 0)
1359: break;
1360: }
1361: panic("tcp_pulloutofband");
1362: }
1363:
1364: #endif /* notdef */
1365:
1366: /*
1367: * Collect new round-trip time estimate
1368: * and update averages and current timeout.
1369: */
1370:
1.1.1.3 root 1371: static void
1372: tcp_xmit_timer(register struct tcpcb *tp, int rtt)
1.1 root 1373: {
1374: register short delta;
1375:
1376: DEBUG_CALL("tcp_xmit_timer");
1377: DEBUG_ARG("tp = %lx", (long)tp);
1378: DEBUG_ARG("rtt = %d", rtt);
1.1.1.3 root 1379:
1.1 root 1380: if (tp->t_srtt != 0) {
1381: /*
1382: * srtt is stored as fixed point with 3 bits after the
1383: * binary point (i.e., scaled by 8). The following magic
1384: * is equivalent to the smoothing algorithm in rfc793 with
1385: * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
1386: * point). Adjust rtt to origin 0.
1387: */
1388: delta = rtt - 1 - (tp->t_srtt >> TCP_RTT_SHIFT);
1389: if ((tp->t_srtt += delta) <= 0)
1390: tp->t_srtt = 1;
1391: /*
1392: * We accumulate a smoothed rtt variance (actually, a
1393: * smoothed mean difference), then set the retransmit
1394: * timer to smoothed rtt + 4 times the smoothed variance.
1395: * rttvar is stored as fixed point with 2 bits after the
1396: * binary point (scaled by 4). The following is
1397: * equivalent to rfc793 smoothing with an alpha of .75
1398: * (rttvar = rttvar*3/4 + |delta| / 4). This replaces
1399: * rfc793's wired-in beta.
1400: */
1401: if (delta < 0)
1402: delta = -delta;
1403: delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT);
1404: if ((tp->t_rttvar += delta) <= 0)
1405: tp->t_rttvar = 1;
1406: } else {
1.1.1.3 root 1407: /*
1.1 root 1408: * No rtt measurement yet - use the unsmoothed rtt.
1409: * Set the variance to half the rtt (so our first
1410: * retransmit happens at 3*rtt).
1411: */
1412: tp->t_srtt = rtt << TCP_RTT_SHIFT;
1413: tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
1414: }
1415: tp->t_rtt = 0;
1416: tp->t_rxtshift = 0;
1417:
1418: /*
1419: * the retransmit should happen at rtt + 4 * rttvar.
1420: * Because of the way we do the smoothing, srtt and rttvar
1421: * will each average +1/2 tick of bias. When we compute
1422: * the retransmit timer, we want 1/2 tick of rounding and
1423: * 1 extra tick because of +-1/2 tick uncertainty in the
1424: * firing of the timer. The bias will give us exactly the
1425: * 1.5 tick we need. But, because the bias is
1426: * statistical, we have to test that we don't drop below
1427: * the minimum feasible timer (which is 2 ticks).
1428: */
1429: TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
1430: (short)tp->t_rttmin, TCPTV_REXMTMAX); /* XXX */
1.1.1.3 root 1431:
1.1 root 1432: /*
1433: * We received an ack for a packet that wasn't retransmitted;
1434: * it is probably safe to discard any error indications we've
1435: * received recently. This isn't quite right, but close enough
1436: * for now (a route might have failed after we sent a segment,
1437: * and the return path might not be symmetrical).
1438: */
1439: tp->t_softerror = 0;
1440: }
1441:
1442: /*
1443: * Determine a reasonable value for maxseg size.
1444: * If the route is known, check route for mtu.
1445: * If none, use an mss that can be handled on the outgoing
1446: * interface without forcing IP to fragment; if bigger than
1447: * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES
1448: * to utilize large mbufs. If no route is found, route has no mtu,
1449: * or the destination isn't local, use a default, hopefully conservative
1450: * size (usually 512 or the default IP max size, but no more than the mtu
1451: * of the interface), as we can't discover anything about intervening
1452: * gateways or networks. We also initialize the congestion/slow start
1453: * window to be a single segment if the destination isn't local.
1454: * While looking at the routing entry, we also initialize other path-dependent
1455: * parameters from pre-set or cached values in the routing entry.
1456: */
1457:
1458: int
1.1.1.5 root 1459: tcp_mss(struct tcpcb *tp, u_int offer)
1.1 root 1460: {
1461: struct socket *so = tp->t_socket;
1462: int mss;
1.1.1.3 root 1463:
1.1 root 1464: DEBUG_CALL("tcp_mss");
1465: DEBUG_ARG("tp = %lx", (long)tp);
1466: DEBUG_ARG("offer = %d", offer);
1.1.1.3 root 1467:
1468: mss = min(IF_MTU, IF_MRU) - sizeof(struct tcpiphdr);
1.1 root 1469: if (offer)
1470: mss = min(mss, offer);
1471: mss = max(mss, 32);
1472: if (mss < tp->t_maxseg || offer != 0)
1473: tp->t_maxseg = mss;
1.1.1.3 root 1474:
1.1 root 1475: tp->snd_cwnd = mss;
1.1.1.3 root 1476:
1477: sbreserve(&so->so_snd, TCP_SNDSPACE + ((TCP_SNDSPACE % mss) ?
1478: (mss - (TCP_SNDSPACE % mss)) :
1479: 0));
1480: sbreserve(&so->so_rcv, TCP_RCVSPACE + ((TCP_RCVSPACE % mss) ?
1481: (mss - (TCP_RCVSPACE % mss)) :
1482: 0));
1483:
1.1 root 1484: DEBUG_MISC((dfd, " returning mss = %d\n", mss));
1.1.1.3 root 1485:
1.1 root 1486: return mss;
1487: }
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