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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) {
1.1.1.7 root 139: m_free(m);
1.1 root 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)));
1.1.1.7 root 173: m_free(m);
1.1 root 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)
1.1.1.7 root 200: m_free(m);
1.1 root 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");
1.1.1.8 ! 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;
1.1.1.7 root 454: m_free(m);
1.1 root 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;
1.1.1.8 ! root 583: DEBUG_MISC((dfd, " tcp fconnect errno = %d-%s\n",
1.1 root 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;
1.1.1.8 ! root 613: tcp_template(tp);
1.1 root 614: }
615: return;
616:
1.1.1.3 root 617: cont_conn:
618: /* m==NULL
1.1 root 619: * Check if the connect succeeded
620: */
621: if (so->so_state & SS_NOFDREF) {
622: tp = tcp_close(tp);
623: goto dropwithreset;
624: }
1.1.1.3 root 625: cont_input:
1.1 root 626: tcp_template(tp);
1.1.1.3 root 627:
1.1 root 628: if (optp)
629: tcp_dooptions(tp, (u_char *)optp, optlen, ti);
1.1.1.3 root 630:
1.1 root 631: if (iss)
632: tp->iss = iss;
1.1.1.3 root 633: else
1.1.1.5 root 634: tp->iss = slirp->tcp_iss;
635: slirp->tcp_iss += TCP_ISSINCR/2;
1.1 root 636: tp->irs = ti->ti_seq;
637: tcp_sendseqinit(tp);
638: tcp_rcvseqinit(tp);
639: tp->t_flags |= TF_ACKNOW;
640: tp->t_state = TCPS_SYN_RECEIVED;
641: tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
642: goto trimthenstep6;
643: } /* case TCPS_LISTEN */
1.1.1.3 root 644:
1.1 root 645: /*
646: * If the state is SYN_SENT:
647: * if seg contains an ACK, but not for our SYN, drop the input.
648: * if seg contains a RST, then drop the connection.
649: * if seg does not contain SYN, then drop it.
650: * Otherwise this is an acceptable SYN segment
651: * initialize tp->rcv_nxt and tp->irs
652: * if seg contains ack then advance tp->snd_una
653: * if SYN has been acked change to ESTABLISHED else SYN_RCVD state
654: * arrange for segment to be acked (eventually)
655: * continue processing rest of data/controls, beginning with URG
656: */
657: case TCPS_SYN_SENT:
658: if ((tiflags & TH_ACK) &&
659: (SEQ_LEQ(ti->ti_ack, tp->iss) ||
660: SEQ_GT(ti->ti_ack, tp->snd_max)))
661: goto dropwithreset;
662:
663: if (tiflags & TH_RST) {
1.1.1.6 root 664: if (tiflags & TH_ACK) {
665: tcp_drop(tp, 0); /* XXX Check t_softerror! */
666: }
1.1 root 667: goto drop;
668: }
669:
670: if ((tiflags & TH_SYN) == 0)
671: goto drop;
672: if (tiflags & TH_ACK) {
673: tp->snd_una = ti->ti_ack;
674: if (SEQ_LT(tp->snd_nxt, tp->snd_una))
675: tp->snd_nxt = tp->snd_una;
676: }
677:
678: tp->t_timer[TCPT_REXMT] = 0;
679: tp->irs = ti->ti_seq;
680: tcp_rcvseqinit(tp);
681: tp->t_flags |= TF_ACKNOW;
682: if (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) {
683: soisfconnected(so);
684: tp->t_state = TCPS_ESTABLISHED;
1.1.1.3 root 685:
1.1 root 686: (void) tcp_reass(tp, (struct tcpiphdr *)0,
687: (struct mbuf *)0);
688: /*
689: * if we didn't have to retransmit the SYN,
690: * use its rtt as our initial srtt & rtt var.
691: */
692: if (tp->t_rtt)
693: tcp_xmit_timer(tp, tp->t_rtt);
694: } else
695: tp->t_state = TCPS_SYN_RECEIVED;
696:
697: trimthenstep6:
698: /*
699: * Advance ti->ti_seq to correspond to first data byte.
700: * If data, trim to stay within window,
701: * dropping FIN if necessary.
702: */
703: ti->ti_seq++;
704: if (ti->ti_len > tp->rcv_wnd) {
705: todrop = ti->ti_len - tp->rcv_wnd;
706: m_adj(m, -todrop);
707: ti->ti_len = tp->rcv_wnd;
708: tiflags &= ~TH_FIN;
709: }
710: tp->snd_wl1 = ti->ti_seq - 1;
711: tp->rcv_up = ti->ti_seq;
712: goto step6;
713: } /* switch tp->t_state */
714: /*
715: * States other than LISTEN or SYN_SENT.
1.1.1.5 root 716: * Check that at least some bytes of segment are within
1.1 root 717: * receive window. If segment begins before rcv_nxt,
718: * drop leading data (and SYN); if nothing left, just ack.
719: */
720: todrop = tp->rcv_nxt - ti->ti_seq;
721: if (todrop > 0) {
722: if (tiflags & TH_SYN) {
723: tiflags &= ~TH_SYN;
724: ti->ti_seq++;
1.1.1.3 root 725: if (ti->ti_urp > 1)
1.1 root 726: ti->ti_urp--;
727: else
728: tiflags &= ~TH_URG;
729: todrop--;
730: }
731: /*
732: * Following if statement from Stevens, vol. 2, p. 960.
733: */
734: if (todrop > ti->ti_len
735: || (todrop == ti->ti_len && (tiflags & TH_FIN) == 0)) {
736: /*
737: * Any valid FIN must be to the left of the window.
738: * At this point the FIN must be a duplicate or out
739: * of sequence; drop it.
740: */
741: tiflags &= ~TH_FIN;
1.1.1.3 root 742:
1.1 root 743: /*
744: * Send an ACK to resynchronize and drop any data.
745: * But keep on processing for RST or ACK.
746: */
747: tp->t_flags |= TF_ACKNOW;
748: todrop = ti->ti_len;
749: }
750: m_adj(m, todrop);
751: ti->ti_seq += todrop;
752: ti->ti_len -= todrop;
753: if (ti->ti_urp > todrop)
754: ti->ti_urp -= todrop;
755: else {
756: tiflags &= ~TH_URG;
757: ti->ti_urp = 0;
758: }
759: }
760: /*
761: * If new data are received on a connection after the
762: * user processes are gone, then RST the other end.
763: */
764: if ((so->so_state & SS_NOFDREF) &&
765: tp->t_state > TCPS_CLOSE_WAIT && ti->ti_len) {
766: tp = tcp_close(tp);
767: goto dropwithreset;
768: }
769:
770: /*
771: * If segment ends after window, drop trailing data
772: * (and PUSH and FIN); if nothing left, just ACK.
773: */
774: todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd);
775: if (todrop > 0) {
776: if (todrop >= ti->ti_len) {
777: /*
778: * If a new connection request is received
779: * while in TIME_WAIT, drop the old connection
780: * and start over if the sequence numbers
781: * are above the previous ones.
782: */
783: if (tiflags & TH_SYN &&
784: tp->t_state == TCPS_TIME_WAIT &&
785: SEQ_GT(ti->ti_seq, tp->rcv_nxt)) {
786: iss = tp->rcv_nxt + TCP_ISSINCR;
787: tp = tcp_close(tp);
788: goto findso;
789: }
790: /*
791: * If window is closed can only take segments at
792: * window edge, and have to drop data and PUSH from
793: * incoming segments. Continue processing, but
794: * remember to ack. Otherwise, drop segment
795: * and ack.
796: */
797: if (tp->rcv_wnd == 0 && ti->ti_seq == tp->rcv_nxt) {
798: tp->t_flags |= TF_ACKNOW;
1.1.1.5 root 799: } else {
1.1 root 800: goto dropafterack;
1.1.1.5 root 801: }
802: }
1.1 root 803: m_adj(m, -todrop);
804: ti->ti_len -= todrop;
805: tiflags &= ~(TH_PUSH|TH_FIN);
806: }
807:
808: /*
809: * If the RST bit is set examine the state:
810: * SYN_RECEIVED STATE:
811: * If passive open, return to LISTEN state.
812: * If active open, inform user that connection was refused.
813: * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES:
814: * Inform user that connection was reset, and close tcb.
815: * CLOSING, LAST_ACK, TIME_WAIT STATES
816: * Close the tcb.
817: */
818: if (tiflags&TH_RST) switch (tp->t_state) {
819:
820: case TCPS_SYN_RECEIVED:
821: case TCPS_ESTABLISHED:
822: case TCPS_FIN_WAIT_1:
823: case TCPS_FIN_WAIT_2:
824: case TCPS_CLOSE_WAIT:
825: tp->t_state = TCPS_CLOSED;
1.1.1.6 root 826: tcp_close(tp);
1.1 root 827: goto drop;
828:
829: case TCPS_CLOSING:
830: case TCPS_LAST_ACK:
831: case TCPS_TIME_WAIT:
1.1.1.6 root 832: tcp_close(tp);
1.1 root 833: goto drop;
834: }
835:
836: /*
837: * If a SYN is in the window, then this is an
838: * error and we send an RST and drop the connection.
839: */
840: if (tiflags & TH_SYN) {
841: tp = tcp_drop(tp,0);
842: goto dropwithreset;
843: }
844:
845: /*
846: * If the ACK bit is off we drop the segment and return.
847: */
848: if ((tiflags & TH_ACK) == 0) goto drop;
849:
850: /*
851: * Ack processing.
852: */
853: switch (tp->t_state) {
854: /*
855: * In SYN_RECEIVED state if the ack ACKs our SYN then enter
856: * ESTABLISHED state and continue processing, otherwise
857: * send an RST. una<=ack<=max
858: */
859: case TCPS_SYN_RECEIVED:
860:
861: if (SEQ_GT(tp->snd_una, ti->ti_ack) ||
862: SEQ_GT(ti->ti_ack, tp->snd_max))
863: goto dropwithreset;
864: tp->t_state = TCPS_ESTABLISHED;
1.1.1.3 root 865: /*
866: * The sent SYN is ack'ed with our sequence number +1
867: * The first data byte already in the buffer will get
1.1 root 868: * lost if no correction is made. This is only needed for
869: * SS_CTL since the buffer is empty otherwise.
1.1.1.3 root 870: * tp->snd_una++; or:
1.1 root 871: */
872: tp->snd_una=ti->ti_ack;
873: if (so->so_state & SS_CTL) {
874: /* So tcp_ctl reports the right state */
875: ret = tcp_ctl(so);
876: if (ret == 1) {
877: soisfconnected(so);
878: so->so_state &= ~SS_CTL; /* success XXX */
879: } else if (ret == 2) {
1.1.1.5 root 880: so->so_state &= SS_PERSISTENT_MASK;
881: so->so_state |= SS_NOFDREF; /* CTL_CMD */
1.1 root 882: } else {
883: needoutput = 1;
884: tp->t_state = TCPS_FIN_WAIT_1;
885: }
886: } else {
887: soisfconnected(so);
888: }
1.1.1.3 root 889:
1.1 root 890: (void) tcp_reass(tp, (struct tcpiphdr *)0, (struct mbuf *)0);
891: tp->snd_wl1 = ti->ti_seq - 1;
892: /* Avoid ack processing; snd_una==ti_ack => dup ack */
893: goto synrx_to_est;
894: /* fall into ... */
895:
896: /*
897: * In ESTABLISHED state: drop duplicate ACKs; ACK out of range
898: * ACKs. If the ack is in the range
899: * tp->snd_una < ti->ti_ack <= tp->snd_max
900: * then advance tp->snd_una to ti->ti_ack and drop
901: * data from the retransmission queue. If this ACK reflects
902: * more up to date window information we update our window information.
903: */
904: case TCPS_ESTABLISHED:
905: case TCPS_FIN_WAIT_1:
906: case TCPS_FIN_WAIT_2:
907: case TCPS_CLOSE_WAIT:
908: case TCPS_CLOSING:
909: case TCPS_LAST_ACK:
910: case TCPS_TIME_WAIT:
911:
912: if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) {
913: if (ti->ti_len == 0 && tiwin == tp->snd_wnd) {
1.1.1.8 ! root 914: DEBUG_MISC((dfd, " dup ack m = %lx so = %lx\n",
1.1 root 915: (long )m, (long )so));
916: /*
917: * If we have outstanding data (other than
918: * a window probe), this is a completely
919: * duplicate ack (ie, window info didn't
920: * change), the ack is the biggest we've
921: * seen and we've seen exactly our rexmt
922: * threshold of them, assume a packet
923: * has been dropped and retransmit it.
924: * Kludge snd_nxt & the congestion
925: * window so we send only this one
926: * packet.
927: *
928: * We know we're losing at the current
929: * window size so do congestion avoidance
930: * (set ssthresh to half the current window
931: * and pull our congestion window back to
932: * the new ssthresh).
933: *
934: * Dup acks mean that packets have left the
1.1.1.3 root 935: * network (they're now cached at the receiver)
1.1 root 936: * so bump cwnd by the amount in the receiver
937: * to keep a constant cwnd packets in the
938: * network.
939: */
940: if (tp->t_timer[TCPT_REXMT] == 0 ||
941: ti->ti_ack != tp->snd_una)
942: tp->t_dupacks = 0;
1.1.1.3 root 943: else if (++tp->t_dupacks == TCPREXMTTHRESH) {
1.1 root 944: tcp_seq onxt = tp->snd_nxt;
945: u_int win =
946: min(tp->snd_wnd, tp->snd_cwnd) / 2 /
947: tp->t_maxseg;
948:
949: if (win < 2)
950: win = 2;
951: tp->snd_ssthresh = win * tp->t_maxseg;
952: tp->t_timer[TCPT_REXMT] = 0;
953: tp->t_rtt = 0;
954: tp->snd_nxt = ti->ti_ack;
955: tp->snd_cwnd = tp->t_maxseg;
956: (void) tcp_output(tp);
957: tp->snd_cwnd = tp->snd_ssthresh +
958: tp->t_maxseg * tp->t_dupacks;
959: if (SEQ_GT(onxt, tp->snd_nxt))
960: tp->snd_nxt = onxt;
961: goto drop;
1.1.1.3 root 962: } else if (tp->t_dupacks > TCPREXMTTHRESH) {
1.1 root 963: tp->snd_cwnd += tp->t_maxseg;
964: (void) tcp_output(tp);
965: goto drop;
966: }
967: } else
968: tp->t_dupacks = 0;
969: break;
970: }
971: synrx_to_est:
972: /*
973: * If the congestion window was inflated to account
974: * for the other side's cached packets, retract it.
975: */
1.1.1.3 root 976: if (tp->t_dupacks > TCPREXMTTHRESH &&
1.1 root 977: tp->snd_cwnd > tp->snd_ssthresh)
978: tp->snd_cwnd = tp->snd_ssthresh;
979: tp->t_dupacks = 0;
980: if (SEQ_GT(ti->ti_ack, tp->snd_max)) {
981: goto dropafterack;
982: }
983: acked = ti->ti_ack - tp->snd_una;
984:
985: /*
1.1.1.5 root 986: * If transmit timer is running and timed sequence
1.1 root 987: * number was acked, update smoothed round trip time.
988: * Since we now have an rtt measurement, cancel the
989: * timer backoff (cf., Phil Karn's retransmit alg.).
990: * Recompute the initial retransmit timer.
991: */
1.1.1.5 root 992: if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq))
1.1 root 993: tcp_xmit_timer(tp,tp->t_rtt);
994:
995: /*
996: * If all outstanding data is acked, stop retransmit
997: * timer and remember to restart (more output or persist).
998: * If there is more data to be acked, restart retransmit
999: * timer, using current (possibly backed-off) value.
1000: */
1001: if (ti->ti_ack == tp->snd_max) {
1002: tp->t_timer[TCPT_REXMT] = 0;
1003: needoutput = 1;
1004: } else if (tp->t_timer[TCPT_PERSIST] == 0)
1005: tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
1006: /*
1007: * When new data is acked, open the congestion window.
1008: * If the window gives us less than ssthresh packets
1009: * in flight, open exponentially (maxseg per packet).
1010: * Otherwise open linearly: maxseg per window
1011: * (maxseg^2 / cwnd per packet).
1012: */
1013: {
1014: register u_int cw = tp->snd_cwnd;
1015: register u_int incr = tp->t_maxseg;
1016:
1017: if (cw > tp->snd_ssthresh)
1018: incr = incr * incr / cw;
1019: tp->snd_cwnd = min(cw + incr, TCP_MAXWIN<<tp->snd_scale);
1020: }
1021: if (acked > so->so_snd.sb_cc) {
1022: tp->snd_wnd -= so->so_snd.sb_cc;
1023: sbdrop(&so->so_snd, (int )so->so_snd.sb_cc);
1024: ourfinisacked = 1;
1025: } else {
1026: sbdrop(&so->so_snd, acked);
1027: tp->snd_wnd -= acked;
1028: ourfinisacked = 0;
1029: }
1030: tp->snd_una = ti->ti_ack;
1031: if (SEQ_LT(tp->snd_nxt, tp->snd_una))
1032: tp->snd_nxt = tp->snd_una;
1033:
1034: switch (tp->t_state) {
1035:
1036: /*
1037: * In FIN_WAIT_1 STATE in addition to the processing
1038: * for the ESTABLISHED state if our FIN is now acknowledged
1039: * then enter FIN_WAIT_2.
1040: */
1041: case TCPS_FIN_WAIT_1:
1042: if (ourfinisacked) {
1043: /*
1044: * If we can't receive any more
1045: * data, then closing user can proceed.
1046: * Starting the timer is contrary to the
1047: * specification, but if we don't get a FIN
1048: * we'll hang forever.
1049: */
1050: if (so->so_state & SS_FCANTRCVMORE) {
1.1.1.3 root 1051: tp->t_timer[TCPT_2MSL] = TCP_MAXIDLE;
1.1 root 1052: }
1053: tp->t_state = TCPS_FIN_WAIT_2;
1054: }
1055: break;
1056:
1057: /*
1058: * In CLOSING STATE in addition to the processing for
1059: * the ESTABLISHED state if the ACK acknowledges our FIN
1060: * then enter the TIME-WAIT state, otherwise ignore
1061: * the segment.
1062: */
1063: case TCPS_CLOSING:
1064: if (ourfinisacked) {
1065: tp->t_state = TCPS_TIME_WAIT;
1066: tcp_canceltimers(tp);
1067: tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1068: }
1069: break;
1070:
1071: /*
1072: * In LAST_ACK, we may still be waiting for data to drain
1073: * and/or to be acked, as well as for the ack of our FIN.
1074: * If our FIN is now acknowledged, delete the TCB,
1075: * enter the closed state and return.
1076: */
1077: case TCPS_LAST_ACK:
1078: if (ourfinisacked) {
1.1.1.6 root 1079: tcp_close(tp);
1.1 root 1080: goto drop;
1081: }
1082: break;
1083:
1084: /*
1085: * In TIME_WAIT state the only thing that should arrive
1086: * is a retransmission of the remote FIN. Acknowledge
1087: * it and restart the finack timer.
1088: */
1089: case TCPS_TIME_WAIT:
1090: tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1091: goto dropafterack;
1092: }
1093: } /* switch(tp->t_state) */
1094:
1095: step6:
1096: /*
1097: * Update window information.
1098: * Don't look at window if no ACK: TAC's send garbage on first SYN.
1099: */
1100: if ((tiflags & TH_ACK) &&
1.1.1.3 root 1101: (SEQ_LT(tp->snd_wl1, ti->ti_seq) ||
1.1 root 1102: (tp->snd_wl1 == ti->ti_seq && (SEQ_LT(tp->snd_wl2, ti->ti_ack) ||
1103: (tp->snd_wl2 == ti->ti_ack && tiwin > tp->snd_wnd))))) {
1104: tp->snd_wnd = tiwin;
1105: tp->snd_wl1 = ti->ti_seq;
1106: tp->snd_wl2 = ti->ti_ack;
1107: if (tp->snd_wnd > tp->max_sndwnd)
1108: tp->max_sndwnd = tp->snd_wnd;
1109: needoutput = 1;
1110: }
1111:
1112: /*
1113: * Process segments with URG.
1114: */
1115: if ((tiflags & TH_URG) && ti->ti_urp &&
1116: TCPS_HAVERCVDFIN(tp->t_state) == 0) {
1117: /*
1118: * This is a kludge, but if we receive and accept
1119: * random urgent pointers, we'll crash in
1120: * soreceive. It's hard to imagine someone
1121: * actually wanting to send this much urgent data.
1122: */
1123: if (ti->ti_urp + so->so_rcv.sb_cc > so->so_rcv.sb_datalen) {
1124: ti->ti_urp = 0;
1125: tiflags &= ~TH_URG;
1126: goto dodata;
1127: }
1128: /*
1129: * If this segment advances the known urgent pointer,
1130: * then mark the data stream. This should not happen
1131: * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
1.1.1.3 root 1132: * a FIN has been received from the remote side.
1.1 root 1133: * In these states we ignore the URG.
1134: *
1135: * According to RFC961 (Assigned Protocols),
1136: * the urgent pointer points to the last octet
1137: * of urgent data. We continue, however,
1138: * to consider it to indicate the first octet
1.1.1.3 root 1139: * of data past the urgent section as the original
1.1 root 1140: * spec states (in one of two places).
1141: */
1142: if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) {
1143: tp->rcv_up = ti->ti_seq + ti->ti_urp;
1144: so->so_urgc = so->so_rcv.sb_cc +
1145: (tp->rcv_up - tp->rcv_nxt); /* -1; */
1146: tp->rcv_up = ti->ti_seq + ti->ti_urp;
1.1.1.3 root 1147:
1.1 root 1148: }
1149: } else
1150: /*
1151: * If no out of band data is expected,
1152: * pull receive urgent pointer along
1153: * with the receive window.
1154: */
1155: if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
1156: tp->rcv_up = tp->rcv_nxt;
1157: dodata:
1158:
1159: /*
1.1.1.8 ! root 1160: * If this is a small packet, then ACK now - with Nagel
! 1161: * congestion avoidance sender won't send more until
! 1162: * he gets an ACK.
! 1163: */
! 1164: if (ti->ti_len && (unsigned)ti->ti_len <= 5 &&
! 1165: ((struct tcpiphdr_2 *)ti)->first_char == (char)27) {
! 1166: tp->t_flags |= TF_ACKNOW;
! 1167: }
! 1168:
! 1169: /*
1.1 root 1170: * Process the segment text, merging it into the TCP sequencing queue,
1171: * and arranging for acknowledgment of receipt if necessary.
1172: * This process logically involves adjusting tp->rcv_wnd as data
1173: * is presented to the user (this happens in tcp_usrreq.c,
1174: * case PRU_RCVD). If a FIN has already been received on this
1175: * connection then we just ignore the text.
1176: */
1177: if ((ti->ti_len || (tiflags&TH_FIN)) &&
1178: TCPS_HAVERCVDFIN(tp->t_state) == 0) {
1179: TCP_REASS(tp, ti, m, so, tiflags);
1180: } else {
1181: m_free(m);
1182: tiflags &= ~TH_FIN;
1183: }
1184:
1185: /*
1186: * If FIN is received ACK the FIN and let the user know
1187: * that the connection is closing.
1188: */
1189: if (tiflags & TH_FIN) {
1190: if (TCPS_HAVERCVDFIN(tp->t_state) == 0) {
1191: /*
1192: * If we receive a FIN we can't send more data,
1193: * set it SS_FDRAIN
1194: * Shutdown the socket if there is no rx data in the
1195: * buffer.
1196: * soread() is called on completion of shutdown() and
1197: * will got to TCPS_LAST_ACK, and use tcp_output()
1198: * to send the FIN.
1199: */
1200: sofwdrain(so);
1.1.1.3 root 1201:
1.1 root 1202: tp->t_flags |= TF_ACKNOW;
1203: tp->rcv_nxt++;
1204: }
1205: switch (tp->t_state) {
1206:
1207: /*
1208: * In SYN_RECEIVED and ESTABLISHED STATES
1209: * enter the CLOSE_WAIT state.
1210: */
1211: case TCPS_SYN_RECEIVED:
1212: case TCPS_ESTABLISHED:
1213: if(so->so_emu == EMU_CTL) /* no shutdown on socket */
1214: tp->t_state = TCPS_LAST_ACK;
1.1.1.3 root 1215: else
1.1 root 1216: tp->t_state = TCPS_CLOSE_WAIT;
1217: break;
1218:
1219: /*
1220: * If still in FIN_WAIT_1 STATE FIN has not been acked so
1221: * enter the CLOSING state.
1222: */
1223: case TCPS_FIN_WAIT_1:
1224: tp->t_state = TCPS_CLOSING;
1225: break;
1226:
1227: /*
1228: * In FIN_WAIT_2 state enter the TIME_WAIT state,
1.1.1.3 root 1229: * starting the time-wait timer, turning off the other
1.1 root 1230: * standard timers.
1231: */
1232: case TCPS_FIN_WAIT_2:
1233: tp->t_state = TCPS_TIME_WAIT;
1234: tcp_canceltimers(tp);
1235: tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1236: break;
1237:
1238: /*
1239: * In TIME_WAIT state restart the 2 MSL time_wait timer.
1240: */
1241: case TCPS_TIME_WAIT:
1242: tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1243: break;
1244: }
1245: }
1246:
1247: /*
1248: * Return any desired output.
1249: */
1250: if (needoutput || (tp->t_flags & TF_ACKNOW)) {
1251: (void) tcp_output(tp);
1252: }
1253: return;
1254:
1255: dropafterack:
1256: /*
1257: * Generate an ACK dropping incoming segment if it occupies
1258: * sequence space, where the ACK reflects our state.
1259: */
1260: if (tiflags & TH_RST)
1261: goto drop;
1.1.1.7 root 1262: m_free(m);
1.1 root 1263: tp->t_flags |= TF_ACKNOW;
1264: (void) tcp_output(tp);
1265: return;
1266:
1267: dropwithreset:
1268: /* reuses m if m!=NULL, m_free() unnecessary */
1269: if (tiflags & TH_ACK)
1270: tcp_respond(tp, ti, m, (tcp_seq)0, ti->ti_ack, TH_RST);
1271: else {
1272: if (tiflags & TH_SYN) ti->ti_len++;
1273: tcp_respond(tp, ti, m, ti->ti_seq+ti->ti_len, (tcp_seq)0,
1274: TH_RST|TH_ACK);
1275: }
1276:
1277: return;
1278:
1279: drop:
1280: /*
1281: * Drop space held by incoming segment and return.
1282: */
1283: m_free(m);
1284:
1285: return;
1286: }
1287:
1.1.1.3 root 1288: static void
1289: tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt, struct tcpiphdr *ti)
1.1 root 1290: {
1.1.1.6 root 1291: uint16_t mss;
1.1 root 1292: int opt, optlen;
1293:
1294: DEBUG_CALL("tcp_dooptions");
1.1.1.8 ! root 1295: DEBUG_ARGS((dfd, " tp = %lx cnt=%i\n", (long)tp, cnt));
1.1 root 1296:
1297: for (; cnt > 0; cnt -= optlen, cp += optlen) {
1298: opt = cp[0];
1299: if (opt == TCPOPT_EOL)
1300: break;
1301: if (opt == TCPOPT_NOP)
1302: optlen = 1;
1303: else {
1304: optlen = cp[1];
1305: if (optlen <= 0)
1306: break;
1307: }
1308: switch (opt) {
1309:
1310: default:
1311: continue;
1312:
1313: case TCPOPT_MAXSEG:
1314: if (optlen != TCPOLEN_MAXSEG)
1315: continue;
1316: if (!(ti->ti_flags & TH_SYN))
1317: continue;
1318: memcpy((char *) &mss, (char *) cp + 2, sizeof(mss));
1319: NTOHS(mss);
1320: (void) tcp_mss(tp, mss); /* sets t_maxseg */
1321: break;
1322: }
1323: }
1324: }
1325:
1326:
1327: /*
1328: * Pull out of band byte out of a segment so
1329: * it doesn't appear in the user's data queue.
1330: * It is still reflected in the segment length for
1331: * sequencing purposes.
1332: */
1333:
1334: #ifdef notdef
1335:
1336: void
1337: tcp_pulloutofband(so, ti, m)
1338: struct socket *so;
1339: struct tcpiphdr *ti;
1340: register struct mbuf *m;
1341: {
1342: int cnt = ti->ti_urp - 1;
1.1.1.3 root 1343:
1.1 root 1344: while (cnt >= 0) {
1345: if (m->m_len > cnt) {
1346: char *cp = mtod(m, caddr_t) + cnt;
1347: struct tcpcb *tp = sototcpcb(so);
1348:
1349: tp->t_iobc = *cp;
1350: tp->t_oobflags |= TCPOOB_HAVEDATA;
1351: memcpy(sp, cp+1, (unsigned)(m->m_len - cnt - 1));
1352: m->m_len--;
1353: return;
1354: }
1355: cnt -= m->m_len;
1356: m = m->m_next; /* XXX WRONG! Fix it! */
1357: if (m == 0)
1358: break;
1359: }
1360: panic("tcp_pulloutofband");
1361: }
1362:
1363: #endif /* notdef */
1364:
1365: /*
1366: * Collect new round-trip time estimate
1367: * and update averages and current timeout.
1368: */
1369:
1.1.1.3 root 1370: static void
1371: tcp_xmit_timer(register struct tcpcb *tp, int rtt)
1.1 root 1372: {
1373: register short delta;
1374:
1375: DEBUG_CALL("tcp_xmit_timer");
1376: DEBUG_ARG("tp = %lx", (long)tp);
1377: DEBUG_ARG("rtt = %d", rtt);
1.1.1.3 root 1378:
1.1 root 1379: if (tp->t_srtt != 0) {
1380: /*
1381: * srtt is stored as fixed point with 3 bits after the
1382: * binary point (i.e., scaled by 8). The following magic
1383: * is equivalent to the smoothing algorithm in rfc793 with
1384: * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
1385: * point). Adjust rtt to origin 0.
1386: */
1387: delta = rtt - 1 - (tp->t_srtt >> TCP_RTT_SHIFT);
1388: if ((tp->t_srtt += delta) <= 0)
1389: tp->t_srtt = 1;
1390: /*
1391: * We accumulate a smoothed rtt variance (actually, a
1392: * smoothed mean difference), then set the retransmit
1393: * timer to smoothed rtt + 4 times the smoothed variance.
1394: * rttvar is stored as fixed point with 2 bits after the
1395: * binary point (scaled by 4). The following is
1396: * equivalent to rfc793 smoothing with an alpha of .75
1397: * (rttvar = rttvar*3/4 + |delta| / 4). This replaces
1398: * rfc793's wired-in beta.
1399: */
1400: if (delta < 0)
1401: delta = -delta;
1402: delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT);
1403: if ((tp->t_rttvar += delta) <= 0)
1404: tp->t_rttvar = 1;
1405: } else {
1.1.1.3 root 1406: /*
1.1 root 1407: * No rtt measurement yet - use the unsmoothed rtt.
1408: * Set the variance to half the rtt (so our first
1409: * retransmit happens at 3*rtt).
1410: */
1411: tp->t_srtt = rtt << TCP_RTT_SHIFT;
1412: tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
1413: }
1414: tp->t_rtt = 0;
1415: tp->t_rxtshift = 0;
1416:
1417: /*
1418: * the retransmit should happen at rtt + 4 * rttvar.
1419: * Because of the way we do the smoothing, srtt and rttvar
1420: * will each average +1/2 tick of bias. When we compute
1421: * the retransmit timer, we want 1/2 tick of rounding and
1422: * 1 extra tick because of +-1/2 tick uncertainty in the
1423: * firing of the timer. The bias will give us exactly the
1424: * 1.5 tick we need. But, because the bias is
1425: * statistical, we have to test that we don't drop below
1426: * the minimum feasible timer (which is 2 ticks).
1427: */
1428: TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
1429: (short)tp->t_rttmin, TCPTV_REXMTMAX); /* XXX */
1.1.1.3 root 1430:
1.1 root 1431: /*
1432: * We received an ack for a packet that wasn't retransmitted;
1433: * it is probably safe to discard any error indications we've
1434: * received recently. This isn't quite right, but close enough
1435: * for now (a route might have failed after we sent a segment,
1436: * and the return path might not be symmetrical).
1437: */
1438: tp->t_softerror = 0;
1439: }
1440:
1441: /*
1442: * Determine a reasonable value for maxseg size.
1443: * If the route is known, check route for mtu.
1444: * If none, use an mss that can be handled on the outgoing
1445: * interface without forcing IP to fragment; if bigger than
1446: * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES
1447: * to utilize large mbufs. If no route is found, route has no mtu,
1448: * or the destination isn't local, use a default, hopefully conservative
1449: * size (usually 512 or the default IP max size, but no more than the mtu
1450: * of the interface), as we can't discover anything about intervening
1451: * gateways or networks. We also initialize the congestion/slow start
1452: * window to be a single segment if the destination isn't local.
1453: * While looking at the routing entry, we also initialize other path-dependent
1454: * parameters from pre-set or cached values in the routing entry.
1455: */
1456:
1457: int
1.1.1.5 root 1458: tcp_mss(struct tcpcb *tp, u_int offer)
1.1 root 1459: {
1460: struct socket *so = tp->t_socket;
1461: int mss;
1.1.1.3 root 1462:
1.1 root 1463: DEBUG_CALL("tcp_mss");
1464: DEBUG_ARG("tp = %lx", (long)tp);
1465: DEBUG_ARG("offer = %d", offer);
1.1.1.3 root 1466:
1467: mss = min(IF_MTU, IF_MRU) - sizeof(struct tcpiphdr);
1.1 root 1468: if (offer)
1469: mss = min(mss, offer);
1470: mss = max(mss, 32);
1471: if (mss < tp->t_maxseg || offer != 0)
1472: tp->t_maxseg = mss;
1.1.1.3 root 1473:
1.1 root 1474: tp->snd_cwnd = mss;
1.1.1.3 root 1475:
1476: sbreserve(&so->so_snd, TCP_SNDSPACE + ((TCP_SNDSPACE % mss) ?
1477: (mss - (TCP_SNDSPACE % mss)) :
1478: 0));
1479: sbreserve(&so->so_rcv, TCP_RCVSPACE + ((TCP_RCVSPACE % mss) ?
1480: (mss - (TCP_RCVSPACE % mss)) :
1481: 0));
1482:
1.1 root 1483: DEBUG_MISC((dfd, " returning mss = %d\n", mss));
1.1.1.3 root 1484:
1.1 root 1485: return mss;
1486: }
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