/*
- * Copyright (c) 1982 Regents of the University of California.
- * All rights reserved. The Berkeley software License Agreement
- * specifies the terms and conditions for redistribution.
+ * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
+ * All rights reserved.
*
- * @(#)tcp_input.c 6.13 (Berkeley) %G%
+ * Redistribution and use in source and binary forms are permitted
+ * provided that the above copyright notice and this paragraph are
+ * duplicated in all such forms and that any documentation,
+ * advertising materials, and other materials related to such
+ * distribution and use acknowledge that the software was developed
+ * by the University of California, Berkeley. The name of the
+ * University may not be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * @(#)tcp_input.c 7.20 (Berkeley) %G%
*/
#include "param.h"
#include "systm.h"
+#include "malloc.h"
#include "mbuf.h"
#include "protosw.h"
#include "socket.h"
#include "tcp_debug.h"
int tcpprintfs = 0;
-int tcpcksum = 1;
+int tcprexmtthresh = 3;
struct tcpiphdr tcp_saveti;
-extern tcpnodelack;
struct tcpcb *tcp_newtcpcb();
* (segment is the next to be received on an established connection,
* and the queue is empty), avoiding linkage into and removal
* from the queue and repetition of various conversions.
+ * Set DELACK for segments received in order, but ack immediately
+ * when segments are out of order (so fast retransmit can work).
*/
#define TCP_REASS(tp, ti, m, so, flags) { \
if ((ti)->ti_seq == (tp)->rcv_nxt && \
(tp)->seg_next == (struct tcpiphdr *)(tp) && \
(tp)->t_state == TCPS_ESTABLISHED) { \
+ tp->t_flags |= TF_DELACK; \
(tp)->rcv_nxt += (ti)->ti_len; \
flags = (ti)->ti_flags & TH_FIN; \
+ tcpstat.tcps_rcvpack++;\
+ tcpstat.tcps_rcvbyte += (ti)->ti_len;\
sbappend(&(so)->so_rcv, (m)); \
sorwakeup(so); \
- } else \
+ } else { \
(flags) = tcp_reass((tp), (ti)); \
+ tp->t_flags |= TF_ACKNOW; \
+ } \
}
tcp_reass(tp, ti)
/* conversion to int (in i) handles seq wraparound */
i = q->ti_seq + q->ti_len - ti->ti_seq;
if (i > 0) {
- if (i >= ti->ti_len)
+ if (i >= ti->ti_len) {
+ tcpstat.tcps_rcvduppack++;
+ tcpstat.tcps_rcvdupbyte += ti->ti_len;
goto drop;
+ }
m_adj(dtom(ti), i);
ti->ti_len -= i;
ti->ti_seq += i;
}
q = (struct tcpiphdr *)(q->ti_next);
}
+ tcpstat.tcps_rcvoopack++;
+ tcpstat.tcps_rcvoobyte += ti->ti_len;
/*
* While we overlap succeeding segments trim them or,
* TCP input routine, follows pages 65-76 of the
* protocol specification dated September, 1981 very closely.
*/
-tcp_input(m0)
- struct mbuf *m0;
+tcp_input(m, iphlen)
+ register struct mbuf *m;
+ int iphlen;
{
register struct tcpiphdr *ti;
struct inpcb *inp;
- register struct mbuf *m;
struct mbuf *om = 0;
int len, tlen, off;
register struct tcpcb *tp = 0;
register int tiflags;
struct socket *so;
- int todrop, acked;
+ int todrop, acked, ourfinisacked, needoutput = 0;
short ostate;
struct in_addr laddr;
int dropsocket = 0;
+ int iss = 0;
+ tcpstat.tcps_rcvtotal++;
/*
* Get IP and TCP header together in first mbuf.
* Note: IP leaves IP header in first mbuf.
*/
- m = m0;
ti = mtod(m, struct tcpiphdr *);
- if (((struct ip *)ti)->ip_hl > (sizeof (struct ip) >> 2))
- ip_stripoptions((struct ip *)ti, (struct mbuf *)0);
- if (m->m_off > MMAXOFF || m->m_len < sizeof (struct tcpiphdr)) {
+ if (iphlen > sizeof (struct ip))
+ ip_stripoptions(m, (struct mbuf *)0);
+ if (m->m_flags & M_EXT || m->m_len < sizeof (struct tcpiphdr)) {
if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) {
- tcpstat.tcps_hdrops++;
+ tcpstat.tcps_rcvshort++;
return;
}
ti = mtod(m, struct tcpiphdr *);
*/
tlen = ((struct ip *)ti)->ip_len;
len = sizeof (struct ip) + tlen;
- if (tcpcksum) {
- ti->ti_next = ti->ti_prev = 0;
- ti->ti_x1 = 0;
- ti->ti_len = (u_short)tlen;
- ti->ti_len = htons((u_short)ti->ti_len);
- if (ti->ti_sum = in_cksum(m, len)) {
- if (tcpprintfs)
- printf("tcp sum: src %x\n", ti->ti_src);
- tcpstat.tcps_badsum++;
- goto drop;
- }
+ ti->ti_next = ti->ti_prev = 0;
+ ti->ti_x1 = 0;
+ ti->ti_len = (u_short)tlen;
+ ti->ti_len = htons((u_short)ti->ti_len);
+ if (ti->ti_sum = in_cksum(m, len)) {
+ if (tcpprintfs)
+ printf("tcp sum: src %x\n", ti->ti_src);
+ tcpstat.tcps_rcvbadsum++;
+ goto drop;
}
/*
if (off < sizeof (struct tcphdr) || off > tlen) {
if (tcpprintfs)
printf("tcp off: src %x off %d\n", ti->ti_src, off);
- tcpstat.tcps_badoff++;
+ tcpstat.tcps_rcvbadoff++;
goto drop;
}
tlen -= off;
if (off > sizeof (struct tcphdr)) {
if (m->m_len < sizeof(struct ip) + off) {
if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) {
- tcpstat.tcps_hdrops++;
+ tcpstat.tcps_rcvshort++;
return;
}
ti = mtod(m, struct tcpiphdr *);
{ caddr_t op = mtod(m, caddr_t) + sizeof (struct tcpiphdr);
bcopy(op, mtod(om, caddr_t), (unsigned)om->m_len);
m->m_len -= om->m_len;
+ m->m_pkthdr.len -= om->m_len;
bcopy(op+om->m_len, op,
(unsigned)(m->m_len-sizeof (struct tcpiphdr)));
}
tiflags = ti->ti_flags;
/*
- * Drop TCP and IP headers.
+ * Drop TCP and IP headers; TCP options were dropped above.
*/
- off += sizeof (struct ip);
- m->m_off += off;
- m->m_len -= off;
+ m->m_data += sizeof(struct tcpiphdr);
+ m->m_len -= sizeof(struct tcpiphdr);
+ m->m_pkthdr.len -= sizeof(struct tcpiphdr);
/*
* Convert TCP protocol specific fields to host format.
/*
* Locate pcb for segment.
*/
+findpcb:
inp = in_pcblookup
(&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport,
INPLOOKUP_WILDCARD);
/*
* If the state is CLOSED (i.e., TCB does not exist) then
* all data in the incoming segment is discarded.
+ * If the TCB exists but is in CLOSED state, it is embryonic,
+ * but should either do a listen or a connect soon.
*/
if (inp == 0)
goto dropwithreset;
tp = intotcpcb(inp);
if (tp == 0)
goto dropwithreset;
+ if (tp->t_state == TCPS_CLOSED)
+ goto drop;
so = inp->inp_socket;
if (so->so_options & SO_DEBUG) {
ostate = tp->t_state;
inp = (struct inpcb *)so->so_pcb;
inp->inp_laddr = ti->ti_dst;
inp->inp_lport = ti->ti_dport;
+#if BSD>=43
inp->inp_options = ip_srcroute();
+#endif
tp = intotcpcb(inp);
tp->t_state = TCPS_LISTEN;
}
* Reset idle time and keep-alive timer.
*/
tp->t_idle = 0;
- tp->t_timer[TCPT_KEEP] = TCPTV_KEEP;
+ tp->t_timer[TCPT_KEEP] = tcp_keepidle;
/*
* Process options if not in LISTEN state,
* Receive window is amount of space in rcv queue,
* but not less than advertised window.
*/
- tp->rcv_wnd = MAX(sbspace(&so->so_rcv), tp->rcv_adv - tp->rcv_nxt);
- if (tp->rcv_wnd < 0)
- tp->rcv_wnd = 0;
+ { int win;
+
+ win = sbspace(&so->so_rcv);
+ if (win < 0)
+ win = 0;
+ tp->rcv_wnd = max(win, (int)(tp->rcv_adv - tp->rcv_nxt));
+ }
switch (tp->t_state) {
* If the state is LISTEN then ignore segment if it contains an RST.
* If the segment contains an ACK then it is bad and send a RST.
* If it does not contain a SYN then it is not interesting; drop it.
+ * Don't bother responding if the destination was a broadcast.
* Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial
* tp->iss, and send a segment:
* <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
goto dropwithreset;
if ((tiflags & TH_SYN) == 0)
goto drop;
+ if (m->m_flags & M_BCAST)
+ goto drop;
am = m_get(M_DONTWAIT, MT_SONAME);
if (am == NULL)
goto drop;
(void) m_free(am);
tp->t_template = tcp_template(tp);
if (tp->t_template == 0) {
- in_pcbdisconnect(inp);
+ tp = tcp_drop(tp, ENOBUFS);
dropsocket = 0; /* socket is already gone */
- tp = 0;
goto drop;
}
if (om) {
tcp_dooptions(tp, om, ti);
om = 0;
}
- tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2;
+ if (iss)
+ tp->iss = iss;
+ else
+ tp->iss = tcp_iss;
+ tcp_iss += TCP_ISSINCR/2;
tp->irs = ti->ti_seq;
tcp_sendseqinit(tp);
tcp_rcvseqinit(tp);
+ tp->t_flags |= TF_ACKNOW;
tp->t_state = TCPS_SYN_RECEIVED;
- tp->t_timer[TCPT_KEEP] = TCPTV_KEEP;
+ tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
dropsocket = 0; /* committed to socket */
+ tcpstat.tcps_accepts++;
goto trimthenstep6;
}
}
if ((tiflags & TH_SYN) == 0)
goto drop;
- tp->snd_una = ti->ti_ack;
- if (SEQ_LT(tp->snd_nxt, tp->snd_una))
- tp->snd_nxt = tp->snd_una;
+ if (tiflags & TH_ACK) {
+ tp->snd_una = ti->ti_ack;
+ if (SEQ_LT(tp->snd_nxt, tp->snd_una))
+ tp->snd_nxt = tp->snd_una;
+ }
tp->t_timer[TCPT_REXMT] = 0;
tp->irs = ti->ti_seq;
tcp_rcvseqinit(tp);
tp->t_flags |= TF_ACKNOW;
- if (SEQ_GT(tp->snd_una, tp->iss)) {
+ if (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) {
+ tcpstat.tcps_connects++;
soisconnected(so);
tp->t_state = TCPS_ESTABLISHED;
- tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp));
+ tp->t_maxseg = min(tp->t_maxseg, tcp_mss(tp));
(void) tcp_reass(tp, (struct tcpiphdr *)0);
+ /*
+ * if we didn't have to retransmit the SYN,
+ * use its rtt as our initial srtt & rtt var.
+ */
+ if (tp->t_rtt) {
+ tp->t_srtt = tp->t_rtt << 3;
+ tp->t_rttvar = tp->t_rtt << 1;
+ TCPT_RANGESET(tp->t_rxtcur,
+ ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1,
+ TCPTV_MIN, TCPTV_REXMTMAX);
+ tp->t_rtt = 0;
+ }
} else
tp->t_state = TCPS_SYN_RECEIVED;
- goto trimthenstep6;
trimthenstep6:
/*
ti->ti_seq++;
if (ti->ti_len > tp->rcv_wnd) {
todrop = ti->ti_len - tp->rcv_wnd;
+#if BSD>=43
m_adj(m, -todrop);
+#else
+ /* XXX work around 4.2 m_adj bug */
+ if (m->m_len) {
+ m_adj(m, -todrop);
+ } else {
+ /* skip tcp/ip header in first mbuf */
+ m_adj(m->m_next, -todrop);
+ }
+#endif
ti->ti_len = tp->rcv_wnd;
- ti->ti_flags &= ~TH_FIN;
+ tiflags &= ~TH_FIN;
+ tcpstat.tcps_rcvpackafterwin++;
+ tcpstat.tcps_rcvbyteafterwin += todrop;
}
tp->snd_wl1 = ti->ti_seq - 1;
+ tp->rcv_up = ti->ti_seq;
goto step6;
}
/*
- * If data is received on a connection after the
+ * States other than LISTEN or SYN_SENT.
+ * First check that at least some bytes of segment are within
+ * receive window. If segment begins before rcv_nxt,
+ * drop leading data (and SYN); if nothing left, just ack.
+ */
+ todrop = tp->rcv_nxt - ti->ti_seq;
+ if (todrop > 0) {
+ if (tiflags & TH_SYN) {
+ tiflags &= ~TH_SYN;
+ ti->ti_seq++;
+ if (ti->ti_urp > 1)
+ ti->ti_urp--;
+ else
+ tiflags &= ~TH_URG;
+ todrop--;
+ }
+ if (todrop > ti->ti_len ||
+ todrop == ti->ti_len && (tiflags&TH_FIN) == 0) {
+ tcpstat.tcps_rcvduppack++;
+ tcpstat.tcps_rcvdupbyte += ti->ti_len;
+ /*
+ * If segment is just one to the left of the window,
+ * check two special cases:
+ * 1. Don't toss RST in response to 4.2-style keepalive.
+ * 2. If the only thing to drop is a FIN, we can drop
+ * it, but check the ACK or we will get into FIN
+ * wars if our FINs crossed (both CLOSING).
+ * In either case, send ACK to resynchronize,
+ * but keep on processing for RST or ACK.
+ */
+ if ((tiflags & TH_FIN && todrop == ti->ti_len + 1)
+#ifdef TCP_COMPAT_42
+ || (tiflags & TH_RST && ti->ti_seq == tp->rcv_nxt - 1)
+#endif
+ ) {
+ todrop = ti->ti_len;
+ tiflags &= ~TH_FIN;
+ tp->t_flags |= TF_ACKNOW;
+ } else
+ goto dropafterack;
+ } else {
+ tcpstat.tcps_rcvpartduppack++;
+ tcpstat.tcps_rcvpartdupbyte += todrop;
+ }
+ m_adj(m, todrop);
+ ti->ti_seq += todrop;
+ ti->ti_len -= todrop;
+ if (ti->ti_urp > todrop)
+ ti->ti_urp -= todrop;
+ else {
+ tiflags &= ~TH_URG;
+ ti->ti_urp = 0;
+ }
+ }
+
+ /*
+ * If new data are received on a connection after the
* user processes are gone, then RST the other end.
*/
- if ((so->so_state & SS_NOFDREF) && tp->t_state > TCPS_CLOSE_WAIT &&
- ti->ti_len) {
+ if ((so->so_state & SS_NOFDREF) &&
+ tp->t_state > TCPS_CLOSE_WAIT && ti->ti_len) {
tp = tcp_close(tp);
+ tcpstat.tcps_rcvafterclose++;
goto dropwithreset;
}
/*
- * States other than LISTEN or SYN_SENT.
- * First check that at least some bytes of segment are within
- * receive window.
+ * If segment ends after window, drop trailing data
+ * (and PUSH and FIN); if nothing left, just ACK.
*/
- if (tp->rcv_wnd == 0) {
- /*
- * If window is closed can only take segments at
- * window edge, and have to drop data and PUSH from
- * incoming segments.
- */
- if (tp->rcv_nxt != ti->ti_seq)
- goto dropafterack;
- if (ti->ti_len > 0) {
- m_adj(m, ti->ti_len);
- ti->ti_len = 0;
- ti->ti_flags &= ~(TH_PUSH|TH_FIN);
- }
- } else {
- /*
- * If segment begins before rcv_nxt, drop leading
- * data (and SYN); if nothing left, just ack.
- */
- todrop = tp->rcv_nxt - ti->ti_seq;
- if (todrop > 0) {
- if (tiflags & TH_SYN) {
- tiflags &= ~TH_SYN;
- ti->ti_flags &= ~TH_SYN;
- ti->ti_seq++;
- if (ti->ti_urp > 1)
- ti->ti_urp--;
- else
- tiflags &= ~TH_URG;
- todrop--;
- }
- if (todrop > ti->ti_len ||
- todrop == ti->ti_len && (tiflags&TH_FIN) == 0)
- goto dropafterack;
- m_adj(m, todrop);
- ti->ti_seq += todrop;
- ti->ti_len -= todrop;
- if (ti->ti_urp > todrop)
- ti->ti_urp -= todrop;
- else {
- tiflags &= ~TH_URG;
- ti->ti_flags &= ~TH_URG;
- ti->ti_urp = 0;
+ todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd);
+ if (todrop > 0) {
+ tcpstat.tcps_rcvpackafterwin++;
+ if (todrop >= ti->ti_len) {
+ tcpstat.tcps_rcvbyteafterwin += ti->ti_len;
+ /*
+ * If a new connection request is received
+ * while in TIME_WAIT, drop the old connection
+ * and start over if the sequence numbers
+ * are above the previous ones.
+ */
+ if (tiflags & TH_SYN &&
+ tp->t_state == TCPS_TIME_WAIT &&
+ SEQ_GT(ti->ti_seq, tp->rcv_nxt)) {
+ iss = tp->rcv_nxt + TCP_ISSINCR;
+ (void) tcp_close(tp);
+ goto findpcb;
}
- }
- /*
- * If segment ends after window, drop trailing data
- * (and PUSH and FIN); if nothing left, just ACK.
- */
- todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd);
- if (todrop > 0) {
- if (todrop >= ti->ti_len)
+ /*
+ * If window is closed can only take segments at
+ * window edge, and have to drop data and PUSH from
+ * incoming segments. Continue processing, but
+ * remember to ack. Otherwise, drop segment
+ * and ack.
+ */
+ if (tp->rcv_wnd == 0 && ti->ti_seq == tp->rcv_nxt) {
+ tp->t_flags |= TF_ACKNOW;
+ tcpstat.tcps_rcvwinprobe++;
+ } else
goto dropafterack;
+ } else
+ tcpstat.tcps_rcvbyteafterwin += todrop;
+#if BSD>=43
+ m_adj(m, -todrop);
+#else
+ /* XXX work around m_adj bug */
+ if (m->m_len) {
m_adj(m, -todrop);
- ti->ti_len -= todrop;
- ti->ti_flags &= ~(TH_PUSH|TH_FIN);
+ } else {
+ /* skip tcp/ip header in first mbuf */
+ m_adj(m->m_next, -todrop);
}
+#endif
+ ti->ti_len -= todrop;
+ tiflags &= ~(TH_PUSH|TH_FIN);
}
/*
if (tiflags&TH_RST) switch (tp->t_state) {
case TCPS_SYN_RECEIVED:
- tp = tcp_drop(tp, ECONNREFUSED);
- goto drop;
+ so->so_error = ECONNREFUSED;
+ goto close;
case TCPS_ESTABLISHED:
case TCPS_FIN_WAIT_1:
case TCPS_FIN_WAIT_2:
case TCPS_CLOSE_WAIT:
- tp = tcp_drop(tp, ECONNRESET);
+ so->so_error = ECONNRESET;
+ close:
+ tp->t_state = TCPS_CLOSED;
+ tcpstat.tcps_drops++;
+ tp = tcp_close(tp);
goto drop;
case TCPS_CLOSING:
/*
* In SYN_RECEIVED state if the ack ACKs our SYN then enter
- * ESTABLISHED state and continue processing, othewise
+ * ESTABLISHED state and continue processing, otherwise
* send an RST.
*/
case TCPS_SYN_RECEIVED:
if (SEQ_GT(tp->snd_una, ti->ti_ack) ||
SEQ_GT(ti->ti_ack, tp->snd_max))
goto dropwithreset;
- tp->snd_una++; /* SYN acked */
- if (SEQ_LT(tp->snd_nxt, tp->snd_una))
- tp->snd_nxt = tp->snd_una;
- tp->t_timer[TCPT_REXMT] = 0;
+ tcpstat.tcps_connects++;
soisconnected(so);
tp->t_state = TCPS_ESTABLISHED;
- tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp));
+ tp->t_maxseg = min(tp->t_maxseg, tcp_mss(tp));
(void) tcp_reass(tp, (struct tcpiphdr *)0);
tp->snd_wl1 = ti->ti_seq - 1;
/* fall into ... */
case TCPS_CLOSING:
case TCPS_LAST_ACK:
case TCPS_TIME_WAIT:
-#define ourfinisacked (acked > 0)
- if (SEQ_LEQ(ti->ti_ack, tp->snd_una))
+ if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) {
+ if (ti->ti_len == 0 && ti->ti_win == tp->snd_wnd) {
+ tcpstat.tcps_rcvdupack++;
+ /*
+ * If we have outstanding data (not a
+ * window probe), this is a completely
+ * duplicate ack (ie, window info didn't
+ * change), the ack is the biggest we've
+ * seen and we've seen exactly our rexmt
+ * threshhold of them, assume a packet
+ * has been dropped and retransmit it.
+ * Kludge snd_nxt & the congestion
+ * window so we send only this one
+ * packet. If this packet fills the
+ * only hole in the receiver's seq.
+ * space, the next real ack will fully
+ * open our window. This means we
+ * have to do the usual slow-start to
+ * not overwhelm an intermediate gateway
+ * with a burst of packets. Leave
+ * here with the congestion window set
+ * to allow 2 packets on the next real
+ * ack and the exp-to-linear thresh
+ * set for half the current window
+ * size (since we know we're losing at
+ * the current window size).
+ */
+ if (tp->t_timer[TCPT_REXMT] == 0 ||
+ ti->ti_ack != tp->snd_una)
+ tp->t_dupacks = 0;
+ else if (++tp->t_dupacks == tcprexmtthresh) {
+ tcp_seq onxt = tp->snd_nxt;
+ u_int win =
+ min(tp->snd_wnd, tp->snd_cwnd) / 2 /
+ tp->t_maxseg;
+
+ if (win < 2)
+ win = 2;
+ tp->snd_ssthresh = win * tp->t_maxseg;
+
+ tp->t_timer[TCPT_REXMT] = 0;
+ tp->t_rtt = 0;
+ tp->snd_nxt = ti->ti_ack;
+ tp->snd_cwnd = tp->t_maxseg;
+ (void) tcp_output(tp);
+
+ if (SEQ_GT(onxt, tp->snd_nxt))
+ tp->snd_nxt = onxt;
+ goto drop;
+ }
+ } else
+ tp->t_dupacks = 0;
break;
- if (SEQ_GT(ti->ti_ack, tp->snd_max))
+ }
+ tp->t_dupacks = 0;
+ if (SEQ_GT(ti->ti_ack, tp->snd_max)) {
+ tcpstat.tcps_rcvacktoomuch++;
goto dropafterack;
+ }
acked = ti->ti_ack - tp->snd_una;
+ tcpstat.tcps_rcvackpack++;
+ tcpstat.tcps_rcvackbyte += acked;
/*
* If transmit timer is running and timed sequence
* number was acked, update smoothed round trip time.
+ * Since we now have an rtt measurement, cancel the
+ * timer backoff (cf., Phil Karn's retransmit alg.).
+ * Recompute the initial retransmit timer.
*/
if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) {
- if (tp->t_srtt == 0)
- tp->t_srtt = tp->t_rtt;
- else
- tp->t_srtt =
- tcp_alpha * tp->t_srtt +
- (1 - tcp_alpha) * tp->t_rtt;
+ tcpstat.tcps_rttupdated++;
+ if (tp->t_srtt != 0) {
+ register short delta;
+
+ /*
+ * srtt is stored as fixed point with 3 bits
+ * after the binary point (i.e., scaled by 8).
+ * The following magic is equivalent
+ * to the smoothing algorithm in rfc793
+ * with an alpha of .875
+ * (srtt = rtt/8 + srtt*7/8 in fixed point).
+ * Adjust t_rtt to origin 0.
+ */
+ delta = tp->t_rtt - 1 - (tp->t_srtt >> 3);
+ if ((tp->t_srtt += delta) <= 0)
+ tp->t_srtt = 1;
+ /*
+ * We accumulate a smoothed rtt variance
+ * (actually, a smoothed mean difference),
+ * then set the retransmit timer to smoothed
+ * rtt + 2 times the smoothed variance.
+ * rttvar is stored as fixed point
+ * with 2 bits after the binary point
+ * (scaled by 4). The following is equivalent
+ * to rfc793 smoothing with an alpha of .75
+ * (rttvar = rttvar*3/4 + |delta| / 4).
+ * This replaces rfc793's wired-in beta.
+ */
+ if (delta < 0)
+ delta = -delta;
+ delta -= (tp->t_rttvar >> 2);
+ if ((tp->t_rttvar += delta) <= 0)
+ tp->t_rttvar = 1;
+ } else {
+ /*
+ * No rtt measurement yet - use the
+ * unsmoothed rtt. Set the variance
+ * to half the rtt (so our first
+ * retransmit happens at 2*rtt)
+ */
+ tp->t_srtt = tp->t_rtt << 3;
+ tp->t_rttvar = tp->t_rtt << 1;
+ }
tp->t_rtt = 0;
+ tp->t_rxtshift = 0;
+ TCPT_RANGESET(tp->t_rxtcur,
+ ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1,
+ TCPTV_MIN, TCPTV_REXMTMAX);
}
- if (ti->ti_ack == tp->snd_max)
+ /*
+ * If all outstanding data is acked, stop retransmit
+ * timer and remember to restart (more output or persist).
+ * If there is more data to be acked, restart retransmit
+ * timer, using current (possibly backed-off) value.
+ */
+ if (ti->ti_ack == tp->snd_max) {
tp->t_timer[TCPT_REXMT] = 0;
- else {
- TCPT_RANGESET(tp->t_timer[TCPT_REXMT],
- tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX);
- tp->t_rxtshift = 0;
- }
+ needoutput = 1;
+ } else if (tp->t_timer[TCPT_PERSIST] == 0)
+ tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
/*
- * When new data is acked, open the congestion window a bit.
+ * When new data is acked, open the congestion window.
+ * If the window gives us less than ssthresh packets
+ * in flight, open exponentially (maxseg per packet).
+ * Otherwise open linearly (maxseg per window,
+ * or maxseg^2 / cwnd per packet).
*/
- if (acked > 0)
- tp->snd_cwnd = MIN(11 * tp->snd_cwnd / 10, 65535);
+ {
+ u_int incr = tp->t_maxseg;
+
+ if (tp->snd_cwnd > tp->snd_ssthresh)
+ incr = max(incr * incr / tp->snd_cwnd, 1);
+
+ tp->snd_cwnd = min(tp->snd_cwnd + incr, USHRT_MAX); /* XXX */
+ }
if (acked > so->so_snd.sb_cc) {
tp->snd_wnd -= so->so_snd.sb_cc;
- sbdrop(&so->so_snd, so->so_snd.sb_cc);
+ sbdrop(&so->so_snd, (int)so->so_snd.sb_cc);
+ ourfinisacked = 1;
} else {
sbdrop(&so->so_snd, acked);
tp->snd_wnd -= acked;
- acked = 0;
+ ourfinisacked = 0;
}
- if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel)
- sowwakeup(so);
+ sowwakeup(so);
tp->snd_una = ti->ti_ack;
if (SEQ_LT(tp->snd_nxt, tp->snd_una))
tp->snd_nxt = tp->snd_una;
*/
if (so->so_state & SS_CANTRCVMORE) {
soisdisconnected(so);
- tp->t_timer[TCPT_2MSL] = TCPTV_MAXIDLE;
+ tp->t_timer[TCPT_2MSL] = tcp_maxidle;
}
tp->t_state = TCPS_FIN_WAIT_2;
}
break;
/*
- * The only thing that can arrive in LAST_ACK state
- * is an acknowledgment of our FIN. If our FIN is now
- * acknowledged, delete the TCB, enter the closed state
- * and return.
+ * In LAST_ACK, we may still be waiting for data to drain
+ * and/or to be acked, as well as for the ack of our FIN.
+ * If our FIN is now acknowledged, delete the TCB,
+ * enter the closed state and return.
*/
case TCPS_LAST_ACK:
- if (ourfinisacked)
+ if (ourfinisacked) {
tp = tcp_close(tp);
- goto drop;
+ goto drop;
+ }
+ break;
/*
* In TIME_WAIT state the only thing that should arrive
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
goto dropafterack;
}
-#undef ourfinisacked
}
step6:
/*
* Update window information.
+ * Don't look at window if no ACK: TAC's send garbage on first SYN.
*/
- if (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq &&
+ if ((tiflags & TH_ACK) &&
+ (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq &&
(SEQ_LT(tp->snd_wl2, ti->ti_ack) ||
- tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd)) {
+ tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd))) {
+ /* keep track of pure window updates */
+ if (ti->ti_len == 0 &&
+ tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd)
+ tcpstat.tcps_rcvwinupd++;
tp->snd_wnd = ti->ti_win;
tp->snd_wl1 = ti->ti_seq;
tp->snd_wl2 = ti->ti_ack;
+ if (tp->snd_wnd > tp->max_sndwnd)
+ tp->max_sndwnd = tp->snd_wnd;
+ needoutput = 1;
}
/*
if ((tiflags & TH_URG) && ti->ti_urp &&
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
/*
- * This is a kludge, but if we receive accept
+ * This is a kludge, but if we receive and accept
* random urgent pointers, we'll crash in
* soreceive. It's hard to imagine someone
* actually wanting to send this much urgent data.
*/
- if (ti->ti_urp + (unsigned) so->so_rcv.sb_cc > 32767) {
+ if (ti->ti_urp + so->so_rcv.sb_cc > SB_MAX) {
ti->ti_urp = 0; /* XXX */
tiflags &= ~TH_URG; /* XXX */
- ti->ti_flags &= ~TH_URG; /* XXX */
- goto badurp; /* XXX */
+ goto dodata; /* XXX */
}
/*
* If this segment advances the known urgent pointer,
* in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
* a FIN has been received from the remote side.
* In these states we ignore the URG.
+ *
+ * According to RFC961 (Assigned Protocols),
+ * the urgent pointer points to the last octet
+ * of urgent data. We continue, however,
+ * to consider it to indicate the first octet
+ * of data past the urgent section
+ * as the original spec states.
*/
if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) {
tp->rcv_up = ti->ti_seq + ti->ti_urp;
* but if two URG's are pending at once, some out-of-band
* data may creep in... ick.
*/
- if (ti->ti_urp <= ti->ti_len)
+ if (ti->ti_urp <= ti->ti_len
+#ifdef SO_OOBINLINE
+ && (so->so_options & SO_OOBINLINE) == 0
+#endif
+ )
tcp_pulloutofband(so, ti);
- }
-badurp: /* XXX */
+ } else
+ /*
+ * If no out of band data is expected,
+ * pull receive urgent pointer along
+ * with the receive window.
+ */
+ if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
+ tp->rcv_up = tp->rcv_nxt;
+dodata: /* XXX */
/*
* Process the segment text, merging it into the TCP sequencing queue,
if ((ti->ti_len || (tiflags&TH_FIN)) &&
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
TCP_REASS(tp, ti, m, so, tiflags);
- if (tcpnodelack == 0)
- tp->t_flags |= TF_DELACK;
- else
- tp->t_flags |= TF_ACKNOW;
+ /*
+ * Note the amount of data that peer has sent into
+ * our window, in order to estimate the sender's
+ * buffer size.
+ */
+ len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt);
+ if (len > tp->max_rcvd)
+ tp->max_rcvd = len;
} else {
m_freem(m);
tiflags &= ~TH_FIN;
/*
* Return any desired output.
*/
- (void) tcp_output(tp);
+ if (needoutput || (tp->t_flags & TF_ACKNOW))
+ (void) tcp_output(tp);
return;
dropafterack:
* Generate an ACK dropping incoming segment if it occupies
* sequence space, where the ACK reflects our state.
*/
- if ((tiflags&TH_RST) ||
- tlen == 0 && (tiflags&(TH_SYN|TH_FIN)) == 0)
+ if (tiflags & TH_RST)
goto drop;
- if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
- tcp_trace(TA_RESPOND, ostate, tp, &tcp_saveti, 0);
- tcp_respond(tp, ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK);
+ m_freem(m);
+ tp->t_flags |= TF_ACKNOW;
+ (void) tcp_output(tp);
return;
dropwithreset:
/*
* Generate a RST, dropping incoming segment.
* Make ACK acceptable to originator of segment.
+ * Don't bother to respond if destination was broadcast.
*/
- if (tiflags & TH_RST)
+ if ((tiflags & TH_RST) || m->m_flags & M_BCAST)
goto drop;
if (tiflags & TH_ACK)
- tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST);
+ tcp_respond(tp, ti, m, (tcp_seq)0, ti->ti_ack, TH_RST);
else {
if (tiflags & TH_SYN)
ti->ti_len++;
- tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0,
+ tcp_respond(tp, ti, m, ti->ti_seq+ti->ti_len, (tcp_seq)0,
TH_RST|TH_ACK);
}
/* destroy temporarily created socket */
continue;
tp->t_maxseg = *(u_short *)(cp + 2);
tp->t_maxseg = ntohs((u_short)tp->t_maxseg);
- tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp));
+ tp->t_maxseg = min(tp->t_maxseg, tcp_mss(tp));
break;
}
}
* Determine a reasonable value for maxseg size.
* If the route is known, use one that can be handled
* on the given interface without forcing IP to fragment.
- * If bigger than a page (CLBYTES), round down to nearest pagesize
- * to utilize pagesize mbufs.
+ * If bigger than an mbuf cluster (MCLBYTES), round down to nearest size
+ * to utilize large mbufs.
* If interface pointer is unavailable, or the destination isn't local,
* use a conservative size (512 or the default IP max size, but no more
* than the mtu of the interface through which we route),
* as we can't discover anything about intervening gateways or networks.
+ * We also initialize the congestion/slow start window to be a single
+ * segment if the destination isn't local; this information should
+ * probably all be saved with the routing entry at the transport level.
*
* This is ugly, and doesn't belong at this level, but has to happen somehow.
*/
}
mss = ifp->if_mtu - sizeof(struct tcpiphdr);
-#if (CLBYTES & (CLBYTES - 1)) == 0
- if (mss > CLBYTES)
- mss &= ~(CLBYTES-1);
+#if (MCLBYTES & (MCLBYTES - 1)) == 0
+ if (mss > MCLBYTES)
+ mss &= ~(MCLBYTES-1);
#else
- if (mss > CLBYTES)
- mss = mss / CLBYTES * CLBYTES;
+ if (mss > MCLBYTES)
+ mss = mss / MCLBYTES * MCLBYTES;
#endif
if (in_localaddr(inp->inp_faddr))
return (mss);
- return (MIN(mss, TCP_MSS));
+
+ mss = min(mss, TCP_MSS);
+ tp->snd_cwnd = mss;
+ return (mss);
+}
+
+#if BSD<43
+/* XXX this belongs in netinet/in.c */
+in_localaddr(in)
+ struct in_addr in;
+{
+ register u_long i = ntohl(in.s_addr);
+ register struct ifnet *ifp;
+ register struct sockaddr_in *sin;
+ register u_long mask;
+
+ if (IN_CLASSA(i))
+ mask = IN_CLASSA_NET;
+ else if (IN_CLASSB(i))
+ mask = IN_CLASSB_NET;
+ else if (IN_CLASSC(i))
+ mask = IN_CLASSC_NET;
+ else
+ return (0);
+
+ i &= mask;
+ for (ifp = ifnet; ifp; ifp = ifp->if_next) {
+ if (ifp->if_addr.sa_family != AF_INET)
+ continue;
+ sin = (struct sockaddr_in *)&ifp->if_addr;
+ if ((sin->sin_addr.s_addr & mask) == i)
+ return (1);
+ }
+ return (0);
}
+#endif