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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:
44: struct socket tcb;
45:
1.1.1.3 root 46: #define TCPREXMTTHRESH 3
1.1 root 47: struct socket *tcp_last_so = &tcb;
48:
49: tcp_seq tcp_iss; /* tcp initial send seq # */
50:
51: #define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * PR_SLOWHZ)
52:
53: /* for modulo comparisons of timestamps */
54: #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0)
55: #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0)
56:
57: /*
58: * Insert segment ti into reassembly queue of tcp with
59: * control block tp. Return TH_FIN if reassembly now includes
60: * a segment with FIN. The macro form does the common case inline
61: * (segment is the next to be received on an established connection,
62: * and the queue is empty), avoiding linkage into and removal
63: * from the queue and repetition of various conversions.
64: * Set DELACK for segments received in order, but ack immediately
65: * when segments are out of order (so fast retransmit can work).
66: */
67: #ifdef TCP_ACK_HACK
68: #define TCP_REASS(tp, ti, m, so, flags) {\
69: if ((ti)->ti_seq == (tp)->rcv_nxt && \
1.1.1.4 ! root 70: tcpfrag_list_empty(tp) && \
1.1 root 71: (tp)->t_state == TCPS_ESTABLISHED) {\
72: if (ti->ti_flags & TH_PUSH) \
73: tp->t_flags |= TF_ACKNOW; \
74: else \
75: tp->t_flags |= TF_DELACK; \
76: (tp)->rcv_nxt += (ti)->ti_len; \
77: flags = (ti)->ti_flags & TH_FIN; \
1.1.1.3 root 78: STAT(tcpstat.tcps_rcvpack++); \
79: STAT(tcpstat.tcps_rcvbyte += (ti)->ti_len); \
1.1 root 80: if (so->so_emu) { \
81: if (tcp_emu((so),(m))) sbappend((so), (m)); \
82: } else \
83: sbappend((so), (m)); \
84: /* sorwakeup(so); */ \
85: } else {\
86: (flags) = tcp_reass((tp), (ti), (m)); \
87: tp->t_flags |= TF_ACKNOW; \
88: } \
89: }
90: #else
91: #define TCP_REASS(tp, ti, m, so, flags) { \
92: if ((ti)->ti_seq == (tp)->rcv_nxt && \
1.1.1.4 ! root 93: tcpfrag_list_empty(tp) && \
1.1 root 94: (tp)->t_state == TCPS_ESTABLISHED) { \
95: tp->t_flags |= TF_DELACK; \
96: (tp)->rcv_nxt += (ti)->ti_len; \
97: flags = (ti)->ti_flags & TH_FIN; \
1.1.1.3 root 98: STAT(tcpstat.tcps_rcvpack++); \
99: STAT(tcpstat.tcps_rcvbyte += (ti)->ti_len); \
1.1 root 100: if (so->so_emu) { \
101: if (tcp_emu((so),(m))) sbappend(so, (m)); \
102: } else \
103: sbappend((so), (m)); \
104: /* sorwakeup(so); */ \
105: } else { \
106: (flags) = tcp_reass((tp), (ti), (m)); \
107: tp->t_flags |= TF_ACKNOW; \
108: } \
109: }
110: #endif
1.1.1.3 root 111: static void tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt,
112: struct tcpiphdr *ti);
113: static void tcp_xmit_timer(register struct tcpcb *tp, int rtt);
114:
115: static int
116: tcp_reass(register struct tcpcb *tp, register struct tcpiphdr *ti,
117: struct mbuf *m)
1.1 root 118: {
119: register struct tcpiphdr *q;
120: struct socket *so = tp->t_socket;
121: int flags;
1.1.1.3 root 122:
1.1 root 123: /*
124: * Call with ti==0 after become established to
125: * force pre-ESTABLISHED data up to user socket.
126: */
127: if (ti == 0)
128: goto present;
129:
130: /*
131: * Find a segment which begins after this one does.
132: */
1.1.1.4 ! root 133: for (q = tcpfrag_list_first(tp); !tcpfrag_list_end(q, tp);
! 134: q = tcpiphdr_next(q))
1.1 root 135: if (SEQ_GT(q->ti_seq, ti->ti_seq))
136: break;
137:
138: /*
139: * If there is a preceding segment, it may provide some of
140: * our data already. If so, drop the data from the incoming
141: * segment. If it provides all of our data, drop us.
142: */
1.1.1.4 ! root 143: if (!tcpfrag_list_end(tcpiphdr_prev(q), tp)) {
1.1 root 144: register int i;
1.1.1.4 ! root 145: q = tcpiphdr_prev(q);
1.1 root 146: /* conversion to int (in i) handles seq wraparound */
147: i = q->ti_seq + q->ti_len - ti->ti_seq;
148: if (i > 0) {
149: if (i >= ti->ti_len) {
1.1.1.3 root 150: STAT(tcpstat.tcps_rcvduppack++);
151: STAT(tcpstat.tcps_rcvdupbyte += ti->ti_len);
1.1 root 152: m_freem(m);
153: /*
154: * Try to present any queued data
155: * at the left window edge to the user.
156: * This is needed after the 3-WHS
157: * completes.
158: */
159: goto present; /* ??? */
160: }
161: m_adj(m, i);
162: ti->ti_len -= i;
163: ti->ti_seq += i;
164: }
1.1.1.4 ! root 165: q = tcpiphdr_next(q);
1.1 root 166: }
1.1.1.3 root 167: STAT(tcpstat.tcps_rcvoopack++);
168: STAT(tcpstat.tcps_rcvoobyte += ti->ti_len);
1.1.1.4 ! root 169: ti->ti_mbuf = m;
1.1 root 170:
171: /*
172: * While we overlap succeeding segments trim them or,
173: * if they are completely covered, dequeue them.
174: */
1.1.1.4 ! root 175: while (!tcpfrag_list_end(q, tp)) {
1.1 root 176: register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq;
177: if (i <= 0)
178: break;
179: if (i < q->ti_len) {
180: q->ti_seq += i;
181: q->ti_len -= i;
1.1.1.4 ! root 182: m_adj(q->ti_mbuf, i);
1.1 root 183: break;
184: }
1.1.1.4 ! root 185: q = tcpiphdr_next(q);
! 186: m = tcpiphdr_prev(q)->ti_mbuf;
! 187: remque(tcpiphdr2qlink(tcpiphdr_prev(q)));
1.1 root 188: m_freem(m);
189: }
190:
191: /*
192: * Stick new segment in its place.
193: */
1.1.1.4 ! root 194: insque(tcpiphdr2qlink(ti), tcpiphdr2qlink(tcpiphdr_prev(q)));
1.1 root 195:
196: present:
197: /*
198: * Present data to user, advancing rcv_nxt through
199: * completed sequence space.
200: */
201: if (!TCPS_HAVEESTABLISHED(tp->t_state))
202: return (0);
1.1.1.4 ! root 203: ti = tcpfrag_list_first(tp);
! 204: if (tcpfrag_list_end(ti, tp) || ti->ti_seq != tp->rcv_nxt)
1.1 root 205: return (0);
206: if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len)
207: return (0);
208: do {
209: tp->rcv_nxt += ti->ti_len;
210: flags = ti->ti_flags & TH_FIN;
1.1.1.4 ! root 211: remque(tcpiphdr2qlink(ti));
! 212: m = ti->ti_mbuf;
! 213: ti = tcpiphdr_next(ti);
1.1 root 214: /* if (so->so_state & SS_FCANTRCVMORE) */
215: if (so->so_state & SS_FCANTSENDMORE)
216: m_freem(m);
217: else {
218: if (so->so_emu) {
219: if (tcp_emu(so,m)) sbappend(so, m);
220: } else
221: sbappend(so, m);
222: }
223: } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt);
224: /* sorwakeup(so); */
225: return (flags);
226: }
227:
228: /*
229: * TCP input routine, follows pages 65-76 of the
230: * protocol specification dated September, 1981 very closely.
231: */
232: void
233: tcp_input(m, iphlen, inso)
234: register struct mbuf *m;
235: int iphlen;
236: struct socket *inso;
237: {
238: struct ip save_ip, *ip;
239: register struct tcpiphdr *ti;
240: caddr_t optp = NULL;
241: int optlen = 0;
242: int len, tlen, off;
243: register struct tcpcb *tp = 0;
244: register int tiflags;
245: struct socket *so = 0;
246: int todrop, acked, ourfinisacked, needoutput = 0;
247: /* int dropsocket = 0; */
248: int iss = 0;
249: u_long tiwin;
250: int ret;
251: /* int ts_present = 0; */
1.1.1.4 ! root 252: struct ex_list *ex_ptr;
1.1 root 253:
254: DEBUG_CALL("tcp_input");
1.1.1.3 root 255: DEBUG_ARGS((dfd," m = %8lx iphlen = %2d inso = %lx\n",
1.1 root 256: (long )m, iphlen, (long )inso ));
1.1.1.3 root 257:
1.1 root 258: /*
259: * If called with m == 0, then we're continuing the connect
260: */
261: if (m == NULL) {
262: so = inso;
1.1.1.3 root 263:
1.1 root 264: /* Re-set a few variables */
265: tp = sototcpcb(so);
266: m = so->so_m;
267: so->so_m = 0;
268: ti = so->so_ti;
269: tiwin = ti->ti_win;
270: tiflags = ti->ti_flags;
1.1.1.3 root 271:
1.1 root 272: goto cont_conn;
273: }
1.1.1.3 root 274:
275:
276: STAT(tcpstat.tcps_rcvtotal++);
1.1 root 277: /*
278: * Get IP and TCP header together in first mbuf.
279: * Note: IP leaves IP header in first mbuf.
280: */
281: ti = mtod(m, struct tcpiphdr *);
282: if (iphlen > sizeof(struct ip )) {
283: ip_stripoptions(m, (struct mbuf *)0);
284: iphlen=sizeof(struct ip );
285: }
286: /* XXX Check if too short */
1.1.1.3 root 287:
1.1 root 288:
289: /*
290: * Save a copy of the IP header in case we want restore it
291: * for sending an ICMP error message in response.
292: */
293: ip=mtod(m, struct ip *);
1.1.1.3 root 294: save_ip = *ip;
1.1 root 295: save_ip.ip_len+= iphlen;
296:
297: /*
298: * Checksum extended TCP header and data.
299: */
300: tlen = ((struct ip *)ti)->ip_len;
1.1.1.4 ! root 301: tcpiphdr2qlink(ti)->next = tcpiphdr2qlink(ti)->prev = 0;
! 302: memset(&ti->ti_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr));
1.1 root 303: ti->ti_x1 = 0;
304: ti->ti_len = htons((u_int16_t)tlen);
305: len = sizeof(struct ip ) + tlen;
306: /* keep checksum for ICMP reply
1.1.1.3 root 307: * ti->ti_sum = cksum(m, len);
1.1 root 308: * if (ti->ti_sum) { */
309: if(cksum(m, len)) {
1.1.1.3 root 310: STAT(tcpstat.tcps_rcvbadsum++);
1.1 root 311: goto drop;
312: }
313:
314: /*
315: * Check that TCP offset makes sense,
316: * pull out TCP options and adjust length. XXX
317: */
318: off = ti->ti_off << 2;
319: if (off < sizeof (struct tcphdr) || off > tlen) {
1.1.1.3 root 320: STAT(tcpstat.tcps_rcvbadoff++);
1.1 root 321: goto drop;
322: }
323: tlen -= off;
324: ti->ti_len = tlen;
325: if (off > sizeof (struct tcphdr)) {
326: optlen = off - sizeof (struct tcphdr);
327: optp = mtod(m, caddr_t) + sizeof (struct tcpiphdr);
328:
1.1.1.3 root 329: /*
1.1 root 330: * Do quick retrieval of timestamp options ("options
331: * prediction?"). If timestamp is the only option and it's
332: * formatted as recommended in RFC 1323 appendix A, we
333: * quickly get the values now and not bother calling
334: * tcp_dooptions(), etc.
335: */
336: /* if ((optlen == TCPOLEN_TSTAMP_APPA ||
337: * (optlen > TCPOLEN_TSTAMP_APPA &&
338: * optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) &&
339: * *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) &&
340: * (ti->ti_flags & TH_SYN) == 0) {
341: * ts_present = 1;
342: * ts_val = ntohl(*(u_int32_t *)(optp + 4));
343: * ts_ecr = ntohl(*(u_int32_t *)(optp + 8));
344: * optp = NULL; / * we've parsed the options * /
345: * }
346: */
347: }
348: tiflags = ti->ti_flags;
1.1.1.3 root 349:
1.1 root 350: /*
351: * Convert TCP protocol specific fields to host format.
352: */
353: NTOHL(ti->ti_seq);
354: NTOHL(ti->ti_ack);
355: NTOHS(ti->ti_win);
356: NTOHS(ti->ti_urp);
357:
358: /*
359: * Drop TCP, IP headers and TCP options.
360: */
361: m->m_data += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
362: m->m_len -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
1.1.1.3 root 363:
1.1.1.4 ! root 364: if (slirp_restrict) {
! 365: for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next)
! 366: if (ex_ptr->ex_fport == ti->ti_dport &&
! 367: (ntohl(ti->ti_dst.s_addr) & 0xff) == ex_ptr->ex_addr)
! 368: break;
! 369:
! 370: if (!ex_ptr)
! 371: goto drop;
! 372: }
1.1 root 373: /*
374: * Locate pcb for segment.
375: */
376: findso:
377: so = tcp_last_so;
378: if (so->so_fport != ti->ti_dport ||
379: so->so_lport != ti->ti_sport ||
380: so->so_laddr.s_addr != ti->ti_src.s_addr ||
381: so->so_faddr.s_addr != ti->ti_dst.s_addr) {
382: so = solookup(&tcb, ti->ti_src, ti->ti_sport,
383: ti->ti_dst, ti->ti_dport);
384: if (so)
385: tcp_last_so = so;
1.1.1.3 root 386: STAT(tcpstat.tcps_socachemiss++);
1.1 root 387: }
388:
389: /*
390: * If the state is CLOSED (i.e., TCB does not exist) then
391: * all data in the incoming segment is discarded.
392: * If the TCB exists but is in CLOSED state, it is embryonic,
393: * but should either do a listen or a connect soon.
394: *
395: * state == CLOSED means we've done socreate() but haven't
1.1.1.3 root 396: * attached it to a protocol yet...
397: *
1.1 root 398: * XXX If a TCB does not exist, and the TH_SYN flag is
399: * the only flag set, then create a session, mark it
400: * as if it was LISTENING, and continue...
401: */
402: if (so == 0) {
403: if ((tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) != TH_SYN)
404: goto dropwithreset;
1.1.1.3 root 405:
1.1 root 406: if ((so = socreate()) == NULL)
407: goto dropwithreset;
408: if (tcp_attach(so) < 0) {
409: free(so); /* Not sofree (if it failed, it's not insqued) */
410: goto dropwithreset;
411: }
1.1.1.3 root 412:
413: sbreserve(&so->so_snd, TCP_SNDSPACE);
414: sbreserve(&so->so_rcv, TCP_RCVSPACE);
415:
1.1 root 416: /* tcp_last_so = so; */ /* XXX ? */
417: /* tp = sototcpcb(so); */
1.1.1.3 root 418:
1.1 root 419: so->so_laddr = ti->ti_src;
420: so->so_lport = ti->ti_sport;
421: so->so_faddr = ti->ti_dst;
422: so->so_fport = ti->ti_dport;
1.1.1.3 root 423:
1.1 root 424: if ((so->so_iptos = tcp_tos(so)) == 0)
425: so->so_iptos = ((struct ip *)ti)->ip_tos;
1.1.1.3 root 426:
1.1 root 427: tp = sototcpcb(so);
428: tp->t_state = TCPS_LISTEN;
429: }
1.1.1.3 root 430:
1.1 root 431: /*
432: * If this is a still-connecting socket, this probably
433: * a retransmit of the SYN. Whether it's a retransmit SYN
434: * or something else, we nuke it.
435: */
436: if (so->so_state & SS_ISFCONNECTING)
437: goto drop;
438:
439: tp = sototcpcb(so);
1.1.1.3 root 440:
1.1 root 441: /* XXX Should never fail */
442: if (tp == 0)
443: goto dropwithreset;
444: if (tp->t_state == TCPS_CLOSED)
445: goto drop;
1.1.1.3 root 446:
1.1 root 447: /* Unscale the window into a 32-bit value. */
448: /* if ((tiflags & TH_SYN) == 0)
449: * tiwin = ti->ti_win << tp->snd_scale;
450: * else
451: */
452: tiwin = ti->ti_win;
453:
454: /*
455: * Segment received on connection.
456: * Reset idle time and keep-alive timer.
457: */
458: tp->t_idle = 0;
1.1.1.3 root 459: if (SO_OPTIONS)
460: tp->t_timer[TCPT_KEEP] = TCPTV_KEEPINTVL;
1.1 root 461: else
1.1.1.3 root 462: tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_IDLE;
1.1 root 463:
464: /*
465: * Process options if not in LISTEN state,
466: * else do it below (after getting remote address).
467: */
468: if (optp && tp->t_state != TCPS_LISTEN)
1.1.1.3 root 469: tcp_dooptions(tp, (u_char *)optp, optlen, ti);
1.1 root 470: /* , */
471: /* &ts_present, &ts_val, &ts_ecr); */
472:
1.1.1.3 root 473: /*
1.1 root 474: * Header prediction: check for the two common cases
475: * of a uni-directional data xfer. If the packet has
476: * no control flags, is in-sequence, the window didn't
477: * change and we're not retransmitting, it's a
478: * candidate. If the length is zero and the ack moved
479: * forward, we're the sender side of the xfer. Just
480: * free the data acked & wake any higher level process
481: * that was blocked waiting for space. If the length
482: * is non-zero and the ack didn't move, we're the
483: * receiver side. If we're getting packets in-order
484: * (the reassembly queue is empty), add the data to
485: * the socket buffer and note that we need a delayed ack.
486: *
487: * XXX Some of these tests are not needed
488: * eg: the tiwin == tp->snd_wnd prevents many more
489: * predictions.. with no *real* advantage..
490: */
491: if (tp->t_state == TCPS_ESTABLISHED &&
492: (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK &&
493: /* (!ts_present || TSTMP_GEQ(ts_val, tp->ts_recent)) && */
494: ti->ti_seq == tp->rcv_nxt &&
495: tiwin && tiwin == tp->snd_wnd &&
496: tp->snd_nxt == tp->snd_max) {
1.1.1.3 root 497: /*
1.1 root 498: * If last ACK falls within this segment's sequence numbers,
499: * record the timestamp.
500: */
501: /* if (ts_present && SEQ_LEQ(ti->ti_seq, tp->last_ack_sent) &&
502: * SEQ_LT(tp->last_ack_sent, ti->ti_seq + ti->ti_len)) {
503: * tp->ts_recent_age = tcp_now;
504: * tp->ts_recent = ts_val;
505: * }
506: */
507: if (ti->ti_len == 0) {
508: if (SEQ_GT(ti->ti_ack, tp->snd_una) &&
509: SEQ_LEQ(ti->ti_ack, tp->snd_max) &&
510: tp->snd_cwnd >= tp->snd_wnd) {
511: /*
512: * this is a pure ack for outstanding data.
513: */
1.1.1.3 root 514: STAT(tcpstat.tcps_predack++);
1.1 root 515: /* if (ts_present)
516: * tcp_xmit_timer(tp, tcp_now-ts_ecr+1);
1.1.1.3 root 517: * else
1.1 root 518: */ if (tp->t_rtt &&
519: SEQ_GT(ti->ti_ack, tp->t_rtseq))
520: tcp_xmit_timer(tp, tp->t_rtt);
521: acked = ti->ti_ack - tp->snd_una;
1.1.1.3 root 522: STAT(tcpstat.tcps_rcvackpack++);
523: STAT(tcpstat.tcps_rcvackbyte += acked);
1.1 root 524: sbdrop(&so->so_snd, acked);
525: tp->snd_una = ti->ti_ack;
526: m_freem(m);
527:
528: /*
529: * If all outstanding data are acked, stop
530: * retransmit timer, otherwise restart timer
531: * using current (possibly backed-off) value.
532: * If process is waiting for space,
533: * wakeup/selwakeup/signal. If data
534: * are ready to send, let tcp_output
535: * decide between more output or persist.
536: */
537: if (tp->snd_una == tp->snd_max)
538: tp->t_timer[TCPT_REXMT] = 0;
539: else if (tp->t_timer[TCPT_PERSIST] == 0)
540: tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
541:
1.1.1.3 root 542: /*
1.1 root 543: * There's room in so_snd, sowwakup will read()
544: * from the socket if we can
545: */
546: /* if (so->so_snd.sb_flags & SB_NOTIFY)
547: * sowwakeup(so);
548: */
1.1.1.3 root 549: /*
1.1 root 550: * This is called because sowwakeup might have
551: * put data into so_snd. Since we don't so sowwakeup,
552: * we don't need this.. XXX???
553: */
554: if (so->so_snd.sb_cc)
555: (void) tcp_output(tp);
556:
557: return;
558: }
559: } else if (ti->ti_ack == tp->snd_una &&
1.1.1.4 ! root 560: tcpfrag_list_empty(tp) &&
1.1 root 561: ti->ti_len <= sbspace(&so->so_rcv)) {
562: /*
563: * this is a pure, in-sequence data packet
564: * with nothing on the reassembly queue and
565: * we have enough buffer space to take it.
566: */
1.1.1.3 root 567: STAT(tcpstat.tcps_preddat++);
1.1 root 568: tp->rcv_nxt += ti->ti_len;
1.1.1.3 root 569: STAT(tcpstat.tcps_rcvpack++);
570: STAT(tcpstat.tcps_rcvbyte += ti->ti_len);
1.1 root 571: /*
572: * Add data to socket buffer.
573: */
574: if (so->so_emu) {
575: if (tcp_emu(so,m)) sbappend(so, m);
576: } else
577: sbappend(so, m);
1.1.1.3 root 578:
579: /*
1.1 root 580: * XXX This is called when data arrives. Later, check
581: * if we can actually write() to the socket
582: * XXX Need to check? It's be NON_BLOCKING
583: */
584: /* sorwakeup(so); */
1.1.1.3 root 585:
1.1 root 586: /*
587: * If this is a short packet, then ACK now - with Nagel
588: * congestion avoidance sender won't send more until
589: * he gets an ACK.
1.1.1.3 root 590: *
1.1.1.2 root 591: * It is better to not delay acks at all to maximize
592: * TCP throughput. See RFC 2581.
1.1.1.3 root 593: */
1.1.1.2 root 594: tp->t_flags |= TF_ACKNOW;
595: tcp_output(tp);
1.1 root 596: return;
597: }
598: } /* header prediction */
599: /*
600: * Calculate amount of space in receive window,
601: * and then do TCP input processing.
602: * Receive window is amount of space in rcv queue,
603: * but not less than advertised window.
604: */
605: { int win;
606: win = sbspace(&so->so_rcv);
607: if (win < 0)
608: win = 0;
609: tp->rcv_wnd = max(win, (int)(tp->rcv_adv - tp->rcv_nxt));
610: }
611:
612: switch (tp->t_state) {
613:
614: /*
615: * If the state is LISTEN then ignore segment if it contains an RST.
616: * If the segment contains an ACK then it is bad and send a RST.
617: * If it does not contain a SYN then it is not interesting; drop it.
618: * Don't bother responding if the destination was a broadcast.
619: * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial
620: * tp->iss, and send a segment:
621: * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
622: * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss.
623: * Fill in remote peer address fields if not previously specified.
624: * Enter SYN_RECEIVED state, and process any other fields of this
625: * segment in this state.
626: */
627: case TCPS_LISTEN: {
628:
629: if (tiflags & TH_RST)
630: goto drop;
631: if (tiflags & TH_ACK)
632: goto dropwithreset;
633: if ((tiflags & TH_SYN) == 0)
634: goto drop;
1.1.1.3 root 635:
1.1 root 636: /*
637: * This has way too many gotos...
638: * But a bit of spaghetti code never hurt anybody :)
639: */
1.1.1.3 root 640:
1.1 root 641: /*
642: * If this is destined for the control address, then flag to
643: * tcp_ctl once connected, otherwise connect
644: */
645: if ((so->so_faddr.s_addr&htonl(0xffffff00)) == special_addr.s_addr) {
646: int lastbyte=ntohl(so->so_faddr.s_addr) & 0xff;
647: if (lastbyte!=CTL_ALIAS && lastbyte!=CTL_DNS) {
648: #if 0
649: if(lastbyte==CTL_CMD || lastbyte==CTL_EXEC) {
650: /* Command or exec adress */
651: so->so_state |= SS_CTL;
1.1.1.3 root 652: } else
1.1 root 653: #endif
654: {
655: /* May be an add exec */
656: for(ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
1.1.1.3 root 657: if(ex_ptr->ex_fport == so->so_fport &&
1.1 root 658: lastbyte == ex_ptr->ex_addr) {
659: so->so_state |= SS_CTL;
660: break;
661: }
662: }
663: }
664: if(so->so_state & SS_CTL) goto cont_input;
665: }
666: /* CTL_ALIAS: Do nothing, tcp_fconnect will be called on it */
667: }
1.1.1.3 root 668:
1.1 root 669: if (so->so_emu & EMU_NOCONNECT) {
670: so->so_emu &= ~EMU_NOCONNECT;
671: goto cont_input;
672: }
1.1.1.3 root 673:
1.1 root 674: if((tcp_fconnect(so) == -1) && (errno != EINPROGRESS) && (errno != EWOULDBLOCK)) {
675: u_char code=ICMP_UNREACH_NET;
676: DEBUG_MISC((dfd," tcp fconnect errno = %d-%s\n",
677: errno,strerror(errno)));
678: if(errno == ECONNREFUSED) {
679: /* ACK the SYN, send RST to refuse the connection */
680: tcp_respond(tp, ti, m, ti->ti_seq+1, (tcp_seq)0,
1.1.1.3 root 681: TH_RST|TH_ACK);
1.1 root 682: } else {
683: if(errno == EHOSTUNREACH) code=ICMP_UNREACH_HOST;
684: HTONL(ti->ti_seq); /* restore tcp header */
685: HTONL(ti->ti_ack);
686: HTONS(ti->ti_win);
687: HTONS(ti->ti_urp);
688: m->m_data -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
689: m->m_len += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
690: *ip=save_ip;
691: icmp_error(m, ICMP_UNREACH,code, 0,strerror(errno));
692: }
693: tp = tcp_close(tp);
694: m_free(m);
695: } else {
696: /*
697: * Haven't connected yet, save the current mbuf
698: * and ti, and return
699: * XXX Some OS's don't tell us whether the connect()
700: * succeeded or not. So we must time it out.
701: */
702: so->so_m = m;
703: so->so_ti = ti;
704: tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
705: tp->t_state = TCPS_SYN_RECEIVED;
706: }
707: return;
708:
1.1.1.3 root 709: cont_conn:
710: /* m==NULL
1.1 root 711: * Check if the connect succeeded
712: */
713: if (so->so_state & SS_NOFDREF) {
714: tp = tcp_close(tp);
715: goto dropwithreset;
716: }
1.1.1.3 root 717: cont_input:
1.1 root 718: tcp_template(tp);
1.1.1.3 root 719:
1.1 root 720: if (optp)
721: tcp_dooptions(tp, (u_char *)optp, optlen, ti);
722: /* , */
723: /* &ts_present, &ts_val, &ts_ecr); */
1.1.1.3 root 724:
1.1 root 725: if (iss)
726: tp->iss = iss;
1.1.1.3 root 727: else
1.1 root 728: tp->iss = tcp_iss;
729: tcp_iss += TCP_ISSINCR/2;
730: tp->irs = ti->ti_seq;
731: tcp_sendseqinit(tp);
732: tcp_rcvseqinit(tp);
733: tp->t_flags |= TF_ACKNOW;
734: tp->t_state = TCPS_SYN_RECEIVED;
735: tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
1.1.1.3 root 736: STAT(tcpstat.tcps_accepts++);
1.1 root 737: goto trimthenstep6;
738: } /* case TCPS_LISTEN */
1.1.1.3 root 739:
1.1 root 740: /*
741: * If the state is SYN_SENT:
742: * if seg contains an ACK, but not for our SYN, drop the input.
743: * if seg contains a RST, then drop the connection.
744: * if seg does not contain SYN, then drop it.
745: * Otherwise this is an acceptable SYN segment
746: * initialize tp->rcv_nxt and tp->irs
747: * if seg contains ack then advance tp->snd_una
748: * if SYN has been acked change to ESTABLISHED else SYN_RCVD state
749: * arrange for segment to be acked (eventually)
750: * continue processing rest of data/controls, beginning with URG
751: */
752: case TCPS_SYN_SENT:
753: if ((tiflags & TH_ACK) &&
754: (SEQ_LEQ(ti->ti_ack, tp->iss) ||
755: SEQ_GT(ti->ti_ack, tp->snd_max)))
756: goto dropwithreset;
757:
758: if (tiflags & TH_RST) {
759: if (tiflags & TH_ACK)
760: tp = tcp_drop(tp,0); /* XXX Check t_softerror! */
761: goto drop;
762: }
763:
764: if ((tiflags & TH_SYN) == 0)
765: goto drop;
766: if (tiflags & TH_ACK) {
767: tp->snd_una = ti->ti_ack;
768: if (SEQ_LT(tp->snd_nxt, tp->snd_una))
769: tp->snd_nxt = tp->snd_una;
770: }
771:
772: tp->t_timer[TCPT_REXMT] = 0;
773: tp->irs = ti->ti_seq;
774: tcp_rcvseqinit(tp);
775: tp->t_flags |= TF_ACKNOW;
776: if (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) {
1.1.1.3 root 777: STAT(tcpstat.tcps_connects++);
1.1 root 778: soisfconnected(so);
779: tp->t_state = TCPS_ESTABLISHED;
1.1.1.3 root 780:
1.1 root 781: /* Do window scaling on this connection? */
782: /* if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
783: * (TF_RCVD_SCALE|TF_REQ_SCALE)) {
784: * tp->snd_scale = tp->requested_s_scale;
785: * tp->rcv_scale = tp->request_r_scale;
786: * }
787: */
788: (void) tcp_reass(tp, (struct tcpiphdr *)0,
789: (struct mbuf *)0);
790: /*
791: * if we didn't have to retransmit the SYN,
792: * use its rtt as our initial srtt & rtt var.
793: */
794: if (tp->t_rtt)
795: tcp_xmit_timer(tp, tp->t_rtt);
796: } else
797: tp->t_state = TCPS_SYN_RECEIVED;
798:
799: trimthenstep6:
800: /*
801: * Advance ti->ti_seq to correspond to first data byte.
802: * If data, trim to stay within window,
803: * dropping FIN if necessary.
804: */
805: ti->ti_seq++;
806: if (ti->ti_len > tp->rcv_wnd) {
807: todrop = ti->ti_len - tp->rcv_wnd;
808: m_adj(m, -todrop);
809: ti->ti_len = tp->rcv_wnd;
810: tiflags &= ~TH_FIN;
1.1.1.3 root 811: STAT(tcpstat.tcps_rcvpackafterwin++);
812: STAT(tcpstat.tcps_rcvbyteafterwin += todrop);
1.1 root 813: }
814: tp->snd_wl1 = ti->ti_seq - 1;
815: tp->rcv_up = ti->ti_seq;
816: goto step6;
817: } /* switch tp->t_state */
818: /*
819: * States other than LISTEN or SYN_SENT.
820: * First check timestamp, if present.
1.1.1.3 root 821: * Then check that at least some bytes of segment are within
1.1 root 822: * receive window. If segment begins before rcv_nxt,
823: * drop leading data (and SYN); if nothing left, just ack.
1.1.1.3 root 824: *
1.1 root 825: * RFC 1323 PAWS: If we have a timestamp reply on this segment
826: * and it's less than ts_recent, drop it.
827: */
828: /* if (ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent &&
829: * TSTMP_LT(ts_val, tp->ts_recent)) {
830: *
831: */ /* Check to see if ts_recent is over 24 days old. */
832: /* if ((int)(tcp_now - tp->ts_recent_age) > TCP_PAWS_IDLE) {
833: */ /*
834: * * Invalidate ts_recent. If this segment updates
835: * * ts_recent, the age will be reset later and ts_recent
836: * * will get a valid value. If it does not, setting
837: * * ts_recent to zero will at least satisfy the
838: * * requirement that zero be placed in the timestamp
839: * * echo reply when ts_recent isn't valid. The
840: * * age isn't reset until we get a valid ts_recent
841: * * because we don't want out-of-order segments to be
842: * * dropped when ts_recent is old.
843: * */
844: /* tp->ts_recent = 0;
845: * } else {
846: * tcpstat.tcps_rcvduppack++;
847: * tcpstat.tcps_rcvdupbyte += ti->ti_len;
848: * tcpstat.tcps_pawsdrop++;
849: * goto dropafterack;
850: * }
851: * }
852: */
853:
854: todrop = tp->rcv_nxt - ti->ti_seq;
855: if (todrop > 0) {
856: if (tiflags & TH_SYN) {
857: tiflags &= ~TH_SYN;
858: ti->ti_seq++;
1.1.1.3 root 859: if (ti->ti_urp > 1)
1.1 root 860: ti->ti_urp--;
861: else
862: tiflags &= ~TH_URG;
863: todrop--;
864: }
865: /*
866: * Following if statement from Stevens, vol. 2, p. 960.
867: */
868: if (todrop > ti->ti_len
869: || (todrop == ti->ti_len && (tiflags & TH_FIN) == 0)) {
870: /*
871: * Any valid FIN must be to the left of the window.
872: * At this point the FIN must be a duplicate or out
873: * of sequence; drop it.
874: */
875: tiflags &= ~TH_FIN;
1.1.1.3 root 876:
1.1 root 877: /*
878: * Send an ACK to resynchronize and drop any data.
879: * But keep on processing for RST or ACK.
880: */
881: tp->t_flags |= TF_ACKNOW;
882: todrop = ti->ti_len;
1.1.1.3 root 883: STAT(tcpstat.tcps_rcvduppack++);
884: STAT(tcpstat.tcps_rcvdupbyte += todrop);
1.1 root 885: } else {
1.1.1.3 root 886: STAT(tcpstat.tcps_rcvpartduppack++);
887: STAT(tcpstat.tcps_rcvpartdupbyte += todrop);
1.1 root 888: }
889: m_adj(m, todrop);
890: ti->ti_seq += todrop;
891: ti->ti_len -= todrop;
892: if (ti->ti_urp > todrop)
893: ti->ti_urp -= todrop;
894: else {
895: tiflags &= ~TH_URG;
896: ti->ti_urp = 0;
897: }
898: }
899: /*
900: * If new data are received on a connection after the
901: * user processes are gone, then RST the other end.
902: */
903: if ((so->so_state & SS_NOFDREF) &&
904: tp->t_state > TCPS_CLOSE_WAIT && ti->ti_len) {
905: tp = tcp_close(tp);
1.1.1.3 root 906: STAT(tcpstat.tcps_rcvafterclose++);
1.1 root 907: goto dropwithreset;
908: }
909:
910: /*
911: * If segment ends after window, drop trailing data
912: * (and PUSH and FIN); if nothing left, just ACK.
913: */
914: todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd);
915: if (todrop > 0) {
1.1.1.3 root 916: STAT(tcpstat.tcps_rcvpackafterwin++);
1.1 root 917: if (todrop >= ti->ti_len) {
1.1.1.3 root 918: STAT(tcpstat.tcps_rcvbyteafterwin += ti->ti_len);
1.1 root 919: /*
920: * If a new connection request is received
921: * while in TIME_WAIT, drop the old connection
922: * and start over if the sequence numbers
923: * are above the previous ones.
924: */
925: if (tiflags & TH_SYN &&
926: tp->t_state == TCPS_TIME_WAIT &&
927: SEQ_GT(ti->ti_seq, tp->rcv_nxt)) {
928: iss = tp->rcv_nxt + TCP_ISSINCR;
929: tp = tcp_close(tp);
930: goto findso;
931: }
932: /*
933: * If window is closed can only take segments at
934: * window edge, and have to drop data and PUSH from
935: * incoming segments. Continue processing, but
936: * remember to ack. Otherwise, drop segment
937: * and ack.
938: */
939: if (tp->rcv_wnd == 0 && ti->ti_seq == tp->rcv_nxt) {
940: tp->t_flags |= TF_ACKNOW;
1.1.1.3 root 941: STAT(tcpstat.tcps_rcvwinprobe++);
1.1 root 942: } else
943: goto dropafterack;
944: } else
1.1.1.3 root 945: STAT(tcpstat.tcps_rcvbyteafterwin += todrop);
1.1 root 946: m_adj(m, -todrop);
947: ti->ti_len -= todrop;
948: tiflags &= ~(TH_PUSH|TH_FIN);
949: }
950:
951: /*
952: * If last ACK falls within this segment's sequence numbers,
953: * record its timestamp.
954: */
955: /* if (ts_present && SEQ_LEQ(ti->ti_seq, tp->last_ack_sent) &&
956: * SEQ_LT(tp->last_ack_sent, ti->ti_seq + ti->ti_len +
957: * ((tiflags & (TH_SYN|TH_FIN)) != 0))) {
958: * tp->ts_recent_age = tcp_now;
959: * tp->ts_recent = ts_val;
960: * }
961: */
962:
963: /*
964: * If the RST bit is set examine the state:
965: * SYN_RECEIVED STATE:
966: * If passive open, return to LISTEN state.
967: * If active open, inform user that connection was refused.
968: * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES:
969: * Inform user that connection was reset, and close tcb.
970: * CLOSING, LAST_ACK, TIME_WAIT STATES
971: * Close the tcb.
972: */
973: if (tiflags&TH_RST) switch (tp->t_state) {
974:
975: case TCPS_SYN_RECEIVED:
976: /* so->so_error = ECONNREFUSED; */
977: goto close;
978:
979: case TCPS_ESTABLISHED:
980: case TCPS_FIN_WAIT_1:
981: case TCPS_FIN_WAIT_2:
982: case TCPS_CLOSE_WAIT:
983: /* so->so_error = ECONNRESET; */
984: close:
985: tp->t_state = TCPS_CLOSED;
1.1.1.3 root 986: STAT(tcpstat.tcps_drops++);
1.1 root 987: tp = tcp_close(tp);
988: goto drop;
989:
990: case TCPS_CLOSING:
991: case TCPS_LAST_ACK:
992: case TCPS_TIME_WAIT:
993: tp = tcp_close(tp);
994: goto drop;
995: }
996:
997: /*
998: * If a SYN is in the window, then this is an
999: * error and we send an RST and drop the connection.
1000: */
1001: if (tiflags & TH_SYN) {
1002: tp = tcp_drop(tp,0);
1003: goto dropwithreset;
1004: }
1005:
1006: /*
1007: * If the ACK bit is off we drop the segment and return.
1008: */
1009: if ((tiflags & TH_ACK) == 0) goto drop;
1010:
1011: /*
1012: * Ack processing.
1013: */
1014: switch (tp->t_state) {
1015: /*
1016: * In SYN_RECEIVED state if the ack ACKs our SYN then enter
1017: * ESTABLISHED state and continue processing, otherwise
1018: * send an RST. una<=ack<=max
1019: */
1020: case TCPS_SYN_RECEIVED:
1021:
1022: if (SEQ_GT(tp->snd_una, ti->ti_ack) ||
1023: SEQ_GT(ti->ti_ack, tp->snd_max))
1024: goto dropwithreset;
1.1.1.3 root 1025: STAT(tcpstat.tcps_connects++);
1.1 root 1026: tp->t_state = TCPS_ESTABLISHED;
1.1.1.3 root 1027: /*
1028: * The sent SYN is ack'ed with our sequence number +1
1029: * The first data byte already in the buffer will get
1.1 root 1030: * lost if no correction is made. This is only needed for
1031: * SS_CTL since the buffer is empty otherwise.
1.1.1.3 root 1032: * tp->snd_una++; or:
1.1 root 1033: */
1034: tp->snd_una=ti->ti_ack;
1035: if (so->so_state & SS_CTL) {
1036: /* So tcp_ctl reports the right state */
1037: ret = tcp_ctl(so);
1038: if (ret == 1) {
1039: soisfconnected(so);
1040: so->so_state &= ~SS_CTL; /* success XXX */
1041: } else if (ret == 2) {
1042: so->so_state = SS_NOFDREF; /* CTL_CMD */
1043: } else {
1044: needoutput = 1;
1045: tp->t_state = TCPS_FIN_WAIT_1;
1046: }
1047: } else {
1048: soisfconnected(so);
1049: }
1.1.1.3 root 1050:
1.1 root 1051: /* Do window scaling? */
1052: /* if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
1053: * (TF_RCVD_SCALE|TF_REQ_SCALE)) {
1054: * tp->snd_scale = tp->requested_s_scale;
1055: * tp->rcv_scale = tp->request_r_scale;
1056: * }
1057: */
1058: (void) tcp_reass(tp, (struct tcpiphdr *)0, (struct mbuf *)0);
1059: tp->snd_wl1 = ti->ti_seq - 1;
1060: /* Avoid ack processing; snd_una==ti_ack => dup ack */
1061: goto synrx_to_est;
1062: /* fall into ... */
1063:
1064: /*
1065: * In ESTABLISHED state: drop duplicate ACKs; ACK out of range
1066: * ACKs. If the ack is in the range
1067: * tp->snd_una < ti->ti_ack <= tp->snd_max
1068: * then advance tp->snd_una to ti->ti_ack and drop
1069: * data from the retransmission queue. If this ACK reflects
1070: * more up to date window information we update our window information.
1071: */
1072: case TCPS_ESTABLISHED:
1073: case TCPS_FIN_WAIT_1:
1074: case TCPS_FIN_WAIT_2:
1075: case TCPS_CLOSE_WAIT:
1076: case TCPS_CLOSING:
1077: case TCPS_LAST_ACK:
1078: case TCPS_TIME_WAIT:
1079:
1080: if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) {
1081: if (ti->ti_len == 0 && tiwin == tp->snd_wnd) {
1.1.1.3 root 1082: STAT(tcpstat.tcps_rcvdupack++);
1.1 root 1083: DEBUG_MISC((dfd," dup ack m = %lx so = %lx \n",
1084: (long )m, (long )so));
1085: /*
1086: * If we have outstanding data (other than
1087: * a window probe), this is a completely
1088: * duplicate ack (ie, window info didn't
1089: * change), the ack is the biggest we've
1090: * seen and we've seen exactly our rexmt
1091: * threshold of them, assume a packet
1092: * has been dropped and retransmit it.
1093: * Kludge snd_nxt & the congestion
1094: * window so we send only this one
1095: * packet.
1096: *
1097: * We know we're losing at the current
1098: * window size so do congestion avoidance
1099: * (set ssthresh to half the current window
1100: * and pull our congestion window back to
1101: * the new ssthresh).
1102: *
1103: * Dup acks mean that packets have left the
1.1.1.3 root 1104: * network (they're now cached at the receiver)
1.1 root 1105: * so bump cwnd by the amount in the receiver
1106: * to keep a constant cwnd packets in the
1107: * network.
1108: */
1109: if (tp->t_timer[TCPT_REXMT] == 0 ||
1110: ti->ti_ack != tp->snd_una)
1111: tp->t_dupacks = 0;
1.1.1.3 root 1112: else if (++tp->t_dupacks == TCPREXMTTHRESH) {
1.1 root 1113: tcp_seq onxt = tp->snd_nxt;
1114: u_int win =
1115: min(tp->snd_wnd, tp->snd_cwnd) / 2 /
1116: tp->t_maxseg;
1117:
1118: if (win < 2)
1119: win = 2;
1120: tp->snd_ssthresh = win * tp->t_maxseg;
1121: tp->t_timer[TCPT_REXMT] = 0;
1122: tp->t_rtt = 0;
1123: tp->snd_nxt = ti->ti_ack;
1124: tp->snd_cwnd = tp->t_maxseg;
1125: (void) tcp_output(tp);
1126: tp->snd_cwnd = tp->snd_ssthresh +
1127: tp->t_maxseg * tp->t_dupacks;
1128: if (SEQ_GT(onxt, tp->snd_nxt))
1129: tp->snd_nxt = onxt;
1130: goto drop;
1.1.1.3 root 1131: } else if (tp->t_dupacks > TCPREXMTTHRESH) {
1.1 root 1132: tp->snd_cwnd += tp->t_maxseg;
1133: (void) tcp_output(tp);
1134: goto drop;
1135: }
1136: } else
1137: tp->t_dupacks = 0;
1138: break;
1139: }
1140: synrx_to_est:
1141: /*
1142: * If the congestion window was inflated to account
1143: * for the other side's cached packets, retract it.
1144: */
1.1.1.3 root 1145: if (tp->t_dupacks > TCPREXMTTHRESH &&
1.1 root 1146: tp->snd_cwnd > tp->snd_ssthresh)
1147: tp->snd_cwnd = tp->snd_ssthresh;
1148: tp->t_dupacks = 0;
1149: if (SEQ_GT(ti->ti_ack, tp->snd_max)) {
1.1.1.3 root 1150: STAT(tcpstat.tcps_rcvacktoomuch++);
1.1 root 1151: goto dropafterack;
1152: }
1153: acked = ti->ti_ack - tp->snd_una;
1.1.1.3 root 1154: STAT(tcpstat.tcps_rcvackpack++);
1155: STAT(tcpstat.tcps_rcvackbyte += acked);
1.1 root 1156:
1157: /*
1158: * If we have a timestamp reply, update smoothed
1159: * round trip time. If no timestamp is present but
1160: * transmit timer is running and timed sequence
1161: * number was acked, update smoothed round trip time.
1162: * Since we now have an rtt measurement, cancel the
1163: * timer backoff (cf., Phil Karn's retransmit alg.).
1164: * Recompute the initial retransmit timer.
1165: */
1166: /* if (ts_present)
1167: * tcp_xmit_timer(tp, tcp_now-ts_ecr+1);
1168: * else
1.1.1.3 root 1169: */
1.1 root 1170: if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq))
1171: tcp_xmit_timer(tp,tp->t_rtt);
1172:
1173: /*
1174: * If all outstanding data is acked, stop retransmit
1175: * timer and remember to restart (more output or persist).
1176: * If there is more data to be acked, restart retransmit
1177: * timer, using current (possibly backed-off) value.
1178: */
1179: if (ti->ti_ack == tp->snd_max) {
1180: tp->t_timer[TCPT_REXMT] = 0;
1181: needoutput = 1;
1182: } else if (tp->t_timer[TCPT_PERSIST] == 0)
1183: tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
1184: /*
1185: * When new data is acked, open the congestion window.
1186: * If the window gives us less than ssthresh packets
1187: * in flight, open exponentially (maxseg per packet).
1188: * Otherwise open linearly: maxseg per window
1189: * (maxseg^2 / cwnd per packet).
1190: */
1191: {
1192: register u_int cw = tp->snd_cwnd;
1193: register u_int incr = tp->t_maxseg;
1194:
1195: if (cw > tp->snd_ssthresh)
1196: incr = incr * incr / cw;
1197: tp->snd_cwnd = min(cw + incr, TCP_MAXWIN<<tp->snd_scale);
1198: }
1199: if (acked > so->so_snd.sb_cc) {
1200: tp->snd_wnd -= so->so_snd.sb_cc;
1201: sbdrop(&so->so_snd, (int )so->so_snd.sb_cc);
1202: ourfinisacked = 1;
1203: } else {
1204: sbdrop(&so->so_snd, acked);
1205: tp->snd_wnd -= acked;
1206: ourfinisacked = 0;
1207: }
1208: /*
1209: * XXX sowwakup is called when data is acked and there's room for
1.1.1.3 root 1210: * for more data... it should read() the socket
1.1 root 1211: */
1212: /* if (so->so_snd.sb_flags & SB_NOTIFY)
1213: * sowwakeup(so);
1214: */
1215: tp->snd_una = ti->ti_ack;
1216: if (SEQ_LT(tp->snd_nxt, tp->snd_una))
1217: tp->snd_nxt = tp->snd_una;
1218:
1219: switch (tp->t_state) {
1220:
1221: /*
1222: * In FIN_WAIT_1 STATE in addition to the processing
1223: * for the ESTABLISHED state if our FIN is now acknowledged
1224: * then enter FIN_WAIT_2.
1225: */
1226: case TCPS_FIN_WAIT_1:
1227: if (ourfinisacked) {
1228: /*
1229: * If we can't receive any more
1230: * data, then closing user can proceed.
1231: * Starting the timer is contrary to the
1232: * specification, but if we don't get a FIN
1233: * we'll hang forever.
1234: */
1235: if (so->so_state & SS_FCANTRCVMORE) {
1236: soisfdisconnected(so);
1.1.1.3 root 1237: tp->t_timer[TCPT_2MSL] = TCP_MAXIDLE;
1.1 root 1238: }
1239: tp->t_state = TCPS_FIN_WAIT_2;
1240: }
1241: break;
1242:
1243: /*
1244: * In CLOSING STATE in addition to the processing for
1245: * the ESTABLISHED state if the ACK acknowledges our FIN
1246: * then enter the TIME-WAIT state, otherwise ignore
1247: * the segment.
1248: */
1249: case TCPS_CLOSING:
1250: if (ourfinisacked) {
1251: tp->t_state = TCPS_TIME_WAIT;
1252: tcp_canceltimers(tp);
1253: tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1254: soisfdisconnected(so);
1255: }
1256: break;
1257:
1258: /*
1259: * In LAST_ACK, we may still be waiting for data to drain
1260: * and/or to be acked, as well as for the ack of our FIN.
1261: * If our FIN is now acknowledged, delete the TCB,
1262: * enter the closed state and return.
1263: */
1264: case TCPS_LAST_ACK:
1265: if (ourfinisacked) {
1266: tp = tcp_close(tp);
1267: goto drop;
1268: }
1269: break;
1270:
1271: /*
1272: * In TIME_WAIT state the only thing that should arrive
1273: * is a retransmission of the remote FIN. Acknowledge
1274: * it and restart the finack timer.
1275: */
1276: case TCPS_TIME_WAIT:
1277: tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1278: goto dropafterack;
1279: }
1280: } /* switch(tp->t_state) */
1281:
1282: step6:
1283: /*
1284: * Update window information.
1285: * Don't look at window if no ACK: TAC's send garbage on first SYN.
1286: */
1287: if ((tiflags & TH_ACK) &&
1.1.1.3 root 1288: (SEQ_LT(tp->snd_wl1, ti->ti_seq) ||
1.1 root 1289: (tp->snd_wl1 == ti->ti_seq && (SEQ_LT(tp->snd_wl2, ti->ti_ack) ||
1290: (tp->snd_wl2 == ti->ti_ack && tiwin > tp->snd_wnd))))) {
1291: /* keep track of pure window updates */
1292: if (ti->ti_len == 0 &&
1293: tp->snd_wl2 == ti->ti_ack && tiwin > tp->snd_wnd)
1.1.1.3 root 1294: STAT(tcpstat.tcps_rcvwinupd++);
1.1 root 1295: tp->snd_wnd = tiwin;
1296: tp->snd_wl1 = ti->ti_seq;
1297: tp->snd_wl2 = ti->ti_ack;
1298: if (tp->snd_wnd > tp->max_sndwnd)
1299: tp->max_sndwnd = tp->snd_wnd;
1300: needoutput = 1;
1301: }
1302:
1303: /*
1304: * Process segments with URG.
1305: */
1306: if ((tiflags & TH_URG) && ti->ti_urp &&
1307: TCPS_HAVERCVDFIN(tp->t_state) == 0) {
1308: /*
1309: * This is a kludge, but if we receive and accept
1310: * random urgent pointers, we'll crash in
1311: * soreceive. It's hard to imagine someone
1312: * actually wanting to send this much urgent data.
1313: */
1314: if (ti->ti_urp + so->so_rcv.sb_cc > so->so_rcv.sb_datalen) {
1315: ti->ti_urp = 0;
1316: tiflags &= ~TH_URG;
1317: goto dodata;
1318: }
1319: /*
1320: * If this segment advances the known urgent pointer,
1321: * then mark the data stream. This should not happen
1322: * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
1.1.1.3 root 1323: * a FIN has been received from the remote side.
1.1 root 1324: * In these states we ignore the URG.
1325: *
1326: * According to RFC961 (Assigned Protocols),
1327: * the urgent pointer points to the last octet
1328: * of urgent data. We continue, however,
1329: * to consider it to indicate the first octet
1.1.1.3 root 1330: * of data past the urgent section as the original
1.1 root 1331: * spec states (in one of two places).
1332: */
1333: if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) {
1334: tp->rcv_up = ti->ti_seq + ti->ti_urp;
1335: so->so_urgc = so->so_rcv.sb_cc +
1336: (tp->rcv_up - tp->rcv_nxt); /* -1; */
1337: tp->rcv_up = ti->ti_seq + ti->ti_urp;
1.1.1.3 root 1338:
1.1 root 1339: }
1340: } else
1341: /*
1342: * If no out of band data is expected,
1343: * pull receive urgent pointer along
1344: * with the receive window.
1345: */
1346: if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
1347: tp->rcv_up = tp->rcv_nxt;
1348: dodata:
1349:
1350: /*
1351: * Process the segment text, merging it into the TCP sequencing queue,
1352: * and arranging for acknowledgment of receipt if necessary.
1353: * This process logically involves adjusting tp->rcv_wnd as data
1354: * is presented to the user (this happens in tcp_usrreq.c,
1355: * case PRU_RCVD). If a FIN has already been received on this
1356: * connection then we just ignore the text.
1357: */
1358: if ((ti->ti_len || (tiflags&TH_FIN)) &&
1359: TCPS_HAVERCVDFIN(tp->t_state) == 0) {
1360: TCP_REASS(tp, ti, m, so, tiflags);
1361: /*
1362: * Note the amount of data that peer has sent into
1363: * our window, in order to estimate the sender's
1364: * buffer size.
1365: */
1366: len = so->so_rcv.sb_datalen - (tp->rcv_adv - tp->rcv_nxt);
1367: } else {
1368: m_free(m);
1369: tiflags &= ~TH_FIN;
1370: }
1371:
1372: /*
1373: * If FIN is received ACK the FIN and let the user know
1374: * that the connection is closing.
1375: */
1376: if (tiflags & TH_FIN) {
1377: if (TCPS_HAVERCVDFIN(tp->t_state) == 0) {
1378: /*
1379: * If we receive a FIN we can't send more data,
1380: * set it SS_FDRAIN
1381: * Shutdown the socket if there is no rx data in the
1382: * buffer.
1383: * soread() is called on completion of shutdown() and
1384: * will got to TCPS_LAST_ACK, and use tcp_output()
1385: * to send the FIN.
1386: */
1387: /* sofcantrcvmore(so); */
1388: sofwdrain(so);
1.1.1.3 root 1389:
1.1 root 1390: tp->t_flags |= TF_ACKNOW;
1391: tp->rcv_nxt++;
1392: }
1393: switch (tp->t_state) {
1394:
1395: /*
1396: * In SYN_RECEIVED and ESTABLISHED STATES
1397: * enter the CLOSE_WAIT state.
1398: */
1399: case TCPS_SYN_RECEIVED:
1400: case TCPS_ESTABLISHED:
1401: if(so->so_emu == EMU_CTL) /* no shutdown on socket */
1402: tp->t_state = TCPS_LAST_ACK;
1.1.1.3 root 1403: else
1.1 root 1404: tp->t_state = TCPS_CLOSE_WAIT;
1405: break;
1406:
1407: /*
1408: * If still in FIN_WAIT_1 STATE FIN has not been acked so
1409: * enter the CLOSING state.
1410: */
1411: case TCPS_FIN_WAIT_1:
1412: tp->t_state = TCPS_CLOSING;
1413: break;
1414:
1415: /*
1416: * In FIN_WAIT_2 state enter the TIME_WAIT state,
1.1.1.3 root 1417: * starting the time-wait timer, turning off the other
1.1 root 1418: * standard timers.
1419: */
1420: case TCPS_FIN_WAIT_2:
1421: tp->t_state = TCPS_TIME_WAIT;
1422: tcp_canceltimers(tp);
1423: tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1424: soisfdisconnected(so);
1425: break;
1426:
1427: /*
1428: * In TIME_WAIT state restart the 2 MSL time_wait timer.
1429: */
1430: case TCPS_TIME_WAIT:
1431: tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1432: break;
1433: }
1434: }
1435:
1436: /*
1437: * If this is a small packet, then ACK now - with Nagel
1438: * congestion avoidance sender won't send more until
1439: * he gets an ACK.
1.1.1.3 root 1440: *
1.1 root 1441: * See above.
1442: */
1443: /* if (ti->ti_len && (unsigned)ti->ti_len < tp->t_maxseg) {
1444: */
1445: /* if ((ti->ti_len && (unsigned)ti->ti_len < tp->t_maxseg &&
1446: * (so->so_iptos & IPTOS_LOWDELAY) == 0) ||
1447: * ((so->so_iptos & IPTOS_LOWDELAY) &&
1448: * ((struct tcpiphdr_2 *)ti)->first_char == (char)27)) {
1449: */
1450: if (ti->ti_len && (unsigned)ti->ti_len <= 5 &&
1451: ((struct tcpiphdr_2 *)ti)->first_char == (char)27) {
1452: tp->t_flags |= TF_ACKNOW;
1453: }
1454:
1455: /*
1456: * Return any desired output.
1457: */
1458: if (needoutput || (tp->t_flags & TF_ACKNOW)) {
1459: (void) tcp_output(tp);
1460: }
1461: return;
1462:
1463: dropafterack:
1464: /*
1465: * Generate an ACK dropping incoming segment if it occupies
1466: * sequence space, where the ACK reflects our state.
1467: */
1468: if (tiflags & TH_RST)
1469: goto drop;
1470: m_freem(m);
1471: tp->t_flags |= TF_ACKNOW;
1472: (void) tcp_output(tp);
1473: return;
1474:
1475: dropwithreset:
1476: /* reuses m if m!=NULL, m_free() unnecessary */
1477: if (tiflags & TH_ACK)
1478: tcp_respond(tp, ti, m, (tcp_seq)0, ti->ti_ack, TH_RST);
1479: else {
1480: if (tiflags & TH_SYN) ti->ti_len++;
1481: tcp_respond(tp, ti, m, ti->ti_seq+ti->ti_len, (tcp_seq)0,
1482: TH_RST|TH_ACK);
1483: }
1484:
1485: return;
1486:
1487: drop:
1488: /*
1489: * Drop space held by incoming segment and return.
1490: */
1491: m_free(m);
1492:
1493: return;
1494: }
1495:
1496: /* , ts_present, ts_val, ts_ecr) */
1497: /* int *ts_present;
1498: * u_int32_t *ts_val, *ts_ecr;
1499: */
1.1.1.3 root 1500: static void
1501: tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt, struct tcpiphdr *ti)
1.1 root 1502: {
1503: u_int16_t mss;
1504: int opt, optlen;
1505:
1506: DEBUG_CALL("tcp_dooptions");
1507: DEBUG_ARGS((dfd," tp = %lx cnt=%i \n", (long )tp, cnt));
1508:
1509: for (; cnt > 0; cnt -= optlen, cp += optlen) {
1510: opt = cp[0];
1511: if (opt == TCPOPT_EOL)
1512: break;
1513: if (opt == TCPOPT_NOP)
1514: optlen = 1;
1515: else {
1516: optlen = cp[1];
1517: if (optlen <= 0)
1518: break;
1519: }
1520: switch (opt) {
1521:
1522: default:
1523: continue;
1524:
1525: case TCPOPT_MAXSEG:
1526: if (optlen != TCPOLEN_MAXSEG)
1527: continue;
1528: if (!(ti->ti_flags & TH_SYN))
1529: continue;
1530: memcpy((char *) &mss, (char *) cp + 2, sizeof(mss));
1531: NTOHS(mss);
1532: (void) tcp_mss(tp, mss); /* sets t_maxseg */
1533: break;
1534:
1535: /* case TCPOPT_WINDOW:
1536: * if (optlen != TCPOLEN_WINDOW)
1537: * continue;
1538: * if (!(ti->ti_flags & TH_SYN))
1539: * continue;
1540: * tp->t_flags |= TF_RCVD_SCALE;
1541: * tp->requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT);
1542: * break;
1543: */
1544: /* case TCPOPT_TIMESTAMP:
1545: * if (optlen != TCPOLEN_TIMESTAMP)
1546: * continue;
1547: * *ts_present = 1;
1548: * memcpy((char *) ts_val, (char *)cp + 2, sizeof(*ts_val));
1549: * NTOHL(*ts_val);
1550: * memcpy((char *) ts_ecr, (char *)cp + 6, sizeof(*ts_ecr));
1551: * NTOHL(*ts_ecr);
1552: *
1.1.1.3 root 1553: */ /*
1.1 root 1554: * * A timestamp received in a SYN makes
1555: * * it ok to send timestamp requests and replies.
1556: * */
1557: /* if (ti->ti_flags & TH_SYN) {
1558: * tp->t_flags |= TF_RCVD_TSTMP;
1559: * tp->ts_recent = *ts_val;
1560: * tp->ts_recent_age = tcp_now;
1561: * }
1562: */ break;
1563: }
1564: }
1565: }
1566:
1567:
1568: /*
1569: * Pull out of band byte out of a segment so
1570: * it doesn't appear in the user's data queue.
1571: * It is still reflected in the segment length for
1572: * sequencing purposes.
1573: */
1574:
1575: #ifdef notdef
1576:
1577: void
1578: tcp_pulloutofband(so, ti, m)
1579: struct socket *so;
1580: struct tcpiphdr *ti;
1581: register struct mbuf *m;
1582: {
1583: int cnt = ti->ti_urp - 1;
1.1.1.3 root 1584:
1.1 root 1585: while (cnt >= 0) {
1586: if (m->m_len > cnt) {
1587: char *cp = mtod(m, caddr_t) + cnt;
1588: struct tcpcb *tp = sototcpcb(so);
1589:
1590: tp->t_iobc = *cp;
1591: tp->t_oobflags |= TCPOOB_HAVEDATA;
1592: memcpy(sp, cp+1, (unsigned)(m->m_len - cnt - 1));
1593: m->m_len--;
1594: return;
1595: }
1596: cnt -= m->m_len;
1597: m = m->m_next; /* XXX WRONG! Fix it! */
1598: if (m == 0)
1599: break;
1600: }
1601: panic("tcp_pulloutofband");
1602: }
1603:
1604: #endif /* notdef */
1605:
1606: /*
1607: * Collect new round-trip time estimate
1608: * and update averages and current timeout.
1609: */
1610:
1.1.1.3 root 1611: static void
1612: tcp_xmit_timer(register struct tcpcb *tp, int rtt)
1.1 root 1613: {
1614: register short delta;
1615:
1616: DEBUG_CALL("tcp_xmit_timer");
1617: DEBUG_ARG("tp = %lx", (long)tp);
1618: DEBUG_ARG("rtt = %d", rtt);
1.1.1.3 root 1619:
1620: STAT(tcpstat.tcps_rttupdated++);
1.1 root 1621: if (tp->t_srtt != 0) {
1622: /*
1623: * srtt is stored as fixed point with 3 bits after the
1624: * binary point (i.e., scaled by 8). The following magic
1625: * is equivalent to the smoothing algorithm in rfc793 with
1626: * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
1627: * point). Adjust rtt to origin 0.
1628: */
1629: delta = rtt - 1 - (tp->t_srtt >> TCP_RTT_SHIFT);
1630: if ((tp->t_srtt += delta) <= 0)
1631: tp->t_srtt = 1;
1632: /*
1633: * We accumulate a smoothed rtt variance (actually, a
1634: * smoothed mean difference), then set the retransmit
1635: * timer to smoothed rtt + 4 times the smoothed variance.
1636: * rttvar is stored as fixed point with 2 bits after the
1637: * binary point (scaled by 4). The following is
1638: * equivalent to rfc793 smoothing with an alpha of .75
1639: * (rttvar = rttvar*3/4 + |delta| / 4). This replaces
1640: * rfc793's wired-in beta.
1641: */
1642: if (delta < 0)
1643: delta = -delta;
1644: delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT);
1645: if ((tp->t_rttvar += delta) <= 0)
1646: tp->t_rttvar = 1;
1647: } else {
1.1.1.3 root 1648: /*
1.1 root 1649: * No rtt measurement yet - use the unsmoothed rtt.
1650: * Set the variance to half the rtt (so our first
1651: * retransmit happens at 3*rtt).
1652: */
1653: tp->t_srtt = rtt << TCP_RTT_SHIFT;
1654: tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
1655: }
1656: tp->t_rtt = 0;
1657: tp->t_rxtshift = 0;
1658:
1659: /*
1660: * the retransmit should happen at rtt + 4 * rttvar.
1661: * Because of the way we do the smoothing, srtt and rttvar
1662: * will each average +1/2 tick of bias. When we compute
1663: * the retransmit timer, we want 1/2 tick of rounding and
1664: * 1 extra tick because of +-1/2 tick uncertainty in the
1665: * firing of the timer. The bias will give us exactly the
1666: * 1.5 tick we need. But, because the bias is
1667: * statistical, we have to test that we don't drop below
1668: * the minimum feasible timer (which is 2 ticks).
1669: */
1670: TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
1671: (short)tp->t_rttmin, TCPTV_REXMTMAX); /* XXX */
1.1.1.3 root 1672:
1.1 root 1673: /*
1674: * We received an ack for a packet that wasn't retransmitted;
1675: * it is probably safe to discard any error indications we've
1676: * received recently. This isn't quite right, but close enough
1677: * for now (a route might have failed after we sent a segment,
1678: * and the return path might not be symmetrical).
1679: */
1680: tp->t_softerror = 0;
1681: }
1682:
1683: /*
1684: * Determine a reasonable value for maxseg size.
1685: * If the route is known, check route for mtu.
1686: * If none, use an mss that can be handled on the outgoing
1687: * interface without forcing IP to fragment; if bigger than
1688: * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES
1689: * to utilize large mbufs. If no route is found, route has no mtu,
1690: * or the destination isn't local, use a default, hopefully conservative
1691: * size (usually 512 or the default IP max size, but no more than the mtu
1692: * of the interface), as we can't discover anything about intervening
1693: * gateways or networks. We also initialize the congestion/slow start
1694: * window to be a single segment if the destination isn't local.
1695: * While looking at the routing entry, we also initialize other path-dependent
1696: * parameters from pre-set or cached values in the routing entry.
1697: */
1698:
1699: int
1700: tcp_mss(tp, offer)
1701: register struct tcpcb *tp;
1702: u_int offer;
1703: {
1704: struct socket *so = tp->t_socket;
1705: int mss;
1.1.1.3 root 1706:
1.1 root 1707: DEBUG_CALL("tcp_mss");
1708: DEBUG_ARG("tp = %lx", (long)tp);
1709: DEBUG_ARG("offer = %d", offer);
1.1.1.3 root 1710:
1711: mss = min(IF_MTU, IF_MRU) - sizeof(struct tcpiphdr);
1.1 root 1712: if (offer)
1713: mss = min(mss, offer);
1714: mss = max(mss, 32);
1715: if (mss < tp->t_maxseg || offer != 0)
1716: tp->t_maxseg = mss;
1.1.1.3 root 1717:
1.1 root 1718: tp->snd_cwnd = mss;
1.1.1.3 root 1719:
1720: sbreserve(&so->so_snd, TCP_SNDSPACE + ((TCP_SNDSPACE % mss) ?
1721: (mss - (TCP_SNDSPACE % mss)) :
1722: 0));
1723: sbreserve(&so->so_rcv, TCP_RCVSPACE + ((TCP_RCVSPACE % mss) ?
1724: (mss - (TCP_RCVSPACE % mss)) :
1725: 0));
1726:
1.1 root 1727: DEBUG_MISC((dfd, " returning mss = %d\n", mss));
1.1.1.3 root 1728:
1.1 root 1729: return mss;
1730: }
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