-/* tcp_input.c 1.47 82/01/13 */
-
-#include "../h/param.h"
-#include "../h/systm.h"
-#include "../h/mbuf.h"
-#include "../h/protosw.h"
-#include "../h/socket.h"
-#include "../h/socketvar.h"
-#include "../net/in.h"
-#include "../net/in_pcb.h"
-#include "../net/in_systm.h"
+/*
+ * Copyright (c) 1982, 1986 Regents of the University of California.
+ * All rights reserved. The Berkeley software License Agreement
+ * specifies the terms and conditions for redistribution.
+ *
+ * @(#)tcp_input.c 7.12 (Berkeley) %G%
+ */
+
+#include "param.h"
+#include "systm.h"
+#include "mbuf.h"
+#include "protosw.h"
+#include "socket.h"
+#include "socketvar.h"
+#include "errno.h"
+
#include "../net/if.h"
-#include "../net/ip.h"
-#include "../net/ip_var.h"
-#include "../net/tcp.h"
-#include "../net/tcp_fsm.h"
-#include "../net/tcp_seq.h"
-#include "../net/tcp_timer.h"
-#include "../net/tcp_var.h"
-#include "../net/tcpip.h"
-#include "../net/tcp_debug.h"
-#include "../errno.h"
+#include "../net/route.h"
+
+#include "in.h"
+#include "in_pcb.h"
+#include "in_systm.h"
+#include "ip.h"
+#include "ip_var.h"
+#include "tcp.h"
+#include "tcp_fsm.h"
+#include "tcp_seq.h"
+#include "tcp_timer.h"
+#include "tcp_var.h"
+#include "tcpip.h"
+#include "tcp_debug.h"
int tcpprintfs = 0;
int tcpcksum = 1;
-struct sockaddr_in tcp_in = { AF_INET };
+int tcprexmtthresh = 3;
struct tcpiphdr tcp_saveti;
+extern tcpnodelack;
struct tcpcb *tcp_newtcpcb();
+
+/*
+ * Insert segment ti into reassembly queue of tcp with
+ * control block tp. Return TH_FIN if reassembly now includes
+ * a segment with FIN. The macro form does the common case inline
+ * (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.
+ */
+#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)->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 \
+ (flags) = tcp_reass((tp), (ti)); \
+}
+
+tcp_reass(tp, ti)
+ register struct tcpcb *tp;
+ register struct tcpiphdr *ti;
+{
+ register struct tcpiphdr *q;
+ struct socket *so = tp->t_inpcb->inp_socket;
+ struct mbuf *m;
+ int flags;
+
+ /*
+ * Call with ti==0 after become established to
+ * force pre-ESTABLISHED data up to user socket.
+ */
+ if (ti == 0)
+ goto present;
+
+ /*
+ * Find a segment which begins after this one does.
+ */
+ for (q = tp->seg_next; q != (struct tcpiphdr *)tp;
+ q = (struct tcpiphdr *)q->ti_next)
+ if (SEQ_GT(q->ti_seq, ti->ti_seq))
+ break;
+
+ /*
+ * If there is a preceding segment, it may provide some of
+ * our data already. If so, drop the data from the incoming
+ * segment. If it provides all of our data, drop us.
+ */
+ if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) {
+ register int i;
+ q = (struct tcpiphdr *)q->ti_prev;
+ /* 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) {
+ 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,
+ * if they are completely covered, dequeue them.
+ */
+ while (q != (struct tcpiphdr *)tp) {
+ register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq;
+ if (i <= 0)
+ break;
+ if (i < q->ti_len) {
+ q->ti_seq += i;
+ q->ti_len -= i;
+ m_adj(dtom(q), i);
+ break;
+ }
+ q = (struct tcpiphdr *)q->ti_next;
+ m = dtom(q->ti_prev);
+ remque(q->ti_prev);
+ m_freem(m);
+ }
+
+ /*
+ * Stick new segment in its place.
+ */
+ insque(ti, q->ti_prev);
+
+present:
+ /*
+ * Present data to user, advancing rcv_nxt through
+ * completed sequence space.
+ */
+ if (TCPS_HAVERCVDSYN(tp->t_state) == 0)
+ return (0);
+ ti = tp->seg_next;
+ if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt)
+ return (0);
+ if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len)
+ return (0);
+ do {
+ tp->rcv_nxt += ti->ti_len;
+ flags = ti->ti_flags & TH_FIN;
+ remque(ti);
+ m = dtom(ti);
+ ti = (struct tcpiphdr *)ti->ti_next;
+ if (so->so_state & SS_CANTRCVMORE)
+ m_freem(m);
+ else
+ sbappend(&so->so_rcv, m);
+ } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt);
+ sorwakeup(so);
+ return (flags);
+drop:
+ m_freem(dtom(ti));
+ return (0);
+}
+
/*
* TCP input routine, follows pages 65-76 of the
* protocol specification dated September, 1981 very closely.
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;
-COUNT(TCP_INPUT);
+ tcpstat.tcps_rcvtotal++;
/*
* Get IP and TCP header together in first mbuf.
* Note: IP leaves IP header in first mbuf.
ip_stripoptions((struct ip *)ti, (struct mbuf *)0);
if (m->m_off > MMAXOFF || 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 *);
ti->ti_next = ti->ti_prev = 0;
ti->ti_x1 = 0;
ti->ti_len = (u_short)tlen;
-#if vax
- ti->ti_len = htons(ti->ti_len);
-#endif
+ ti->ti_len = htons((u_short)ti->ti_len);
if (ti->ti_sum = in_cksum(m, len)) {
- tcpstat.tcps_badsum++;
- printf("tcp cksum %x\n", ti->ti_sum);
+ if (tcpprintfs)
+ printf("tcp sum: src %x\n", ti->ti_src);
+ tcpstat.tcps_rcvbadsum++;
goto drop;
}
}
/*
* Check that TCP offset makes sense,
- * process TCP options and adjust length.
+ * pull out TCP options and adjust length.
*/
off = ti->ti_off << 2;
if (off < sizeof (struct tcphdr) || off > tlen) {
- tcpstat.tcps_badoff++;
+ if (tcpprintfs)
+ printf("tcp off: src %x off %d\n", ti->ti_src, off);
+ tcpstat.tcps_rcvbadoff++;
goto drop;
}
- ti->ti_len = tlen - off;
-#if 0
- if (off > sizeof (struct tcphdr))
- tcp_options(ti);
-#endif
+ tlen -= off;
+ ti->ti_len = tlen;
+ 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_rcvshort++;
+ return;
+ }
+ ti = mtod(m, struct tcpiphdr *);
+ }
+ om = m_get(M_DONTWAIT, MT_DATA);
+ if (om == 0)
+ goto drop;
+ om->m_len = off - sizeof (struct tcphdr);
+ { 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;
+ bcopy(op+om->m_len, op,
+ (unsigned)(m->m_len-sizeof (struct tcpiphdr)));
+ }
+ }
tiflags = ti->ti_flags;
-#if vax
+ /*
+ * Drop TCP and IP headers; TCP options were dropped above.
+ */
+ m->m_off += sizeof(struct tcpiphdr);
+ m->m_len -= sizeof(struct tcpiphdr);
+
/*
* Convert TCP protocol specific fields to host format.
*/
ti->ti_ack = ntohl(ti->ti_ack);
ti->ti_win = ntohs(ti->ti_win);
ti->ti_urp = ntohs(ti->ti_urp);
-#endif
/*
* Locate pcb for segment.
*/
+findpcb:
inp = in_pcblookup
- (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport);
+ (&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;
tcp_saveti = *ti;
}
+ if (so->so_options & SO_ACCEPTCONN) {
+ so = sonewconn(so);
+ if (so == 0)
+ goto drop;
+ /*
+ * This is ugly, but ....
+ *
+ * Mark socket as temporary until we're
+ * committed to keeping it. The code at
+ * ``drop'' and ``dropwithreset'' check the
+ * flag dropsocket to see if the temporary
+ * socket created here should be discarded.
+ * We mark the socket as discardable until
+ * we're committed to it below in TCPS_LISTEN.
+ */
+ dropsocket++;
+ inp = (struct inpcb *)so->so_pcb;
+ inp->inp_laddr = ti->ti_dst;
+ inp->inp_lport = ti->ti_dport;
+ inp->inp_options = ip_srcroute();
+ tp = intotcpcb(inp);
+ tp->t_state = TCPS_LISTEN;
+ }
/*
* Segment received on connection.
tp->t_idle = 0;
tp->t_timer[TCPT_KEEP] = TCPTV_KEEP;
+ /*
+ * Process options if not in LISTEN state,
+ * else do it below (after getting remote address).
+ */
+ if (om && tp->t_state != TCPS_LISTEN) {
+ tcp_dooptions(tp, om, ti);
+ om = 0;
+ }
+
/*
* Calculate amount of space in receive window,
* and then do TCP input processing.
+ * Receive window is amount of space in rcv queue,
+ * but not less than advertised window.
*/
- tp->rcv_wnd = sbspace(&so->so_rcv);
- 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>
* Enter SYN_RECEIVED state, and process any other fields of this
* segment in this state.
*/
- case TCPS_LISTEN:
+ case TCPS_LISTEN: {
+ struct mbuf *am;
+ register struct sockaddr_in *sin;
+
if (tiflags & TH_RST)
goto drop;
if (tiflags & TH_ACK)
goto dropwithreset;
if ((tiflags & TH_SYN) == 0)
goto drop;
- tcp_in.sin_addr = ti->ti_src;
- tcp_in.sin_port = ti->ti_sport;
- if (in_pcbconnect(inp, (struct sockaddr *)&tcp_in))
+ if (in_broadcast(ti->ti_dst))
+ goto drop;
+ am = m_get(M_DONTWAIT, MT_SONAME);
+ if (am == NULL)
+ goto drop;
+ am->m_len = sizeof (struct sockaddr_in);
+ sin = mtod(am, struct sockaddr_in *);
+ sin->sin_family = AF_INET;
+ sin->sin_addr = ti->ti_src;
+ sin->sin_port = ti->ti_sport;
+ laddr = inp->inp_laddr;
+ if (inp->inp_laddr.s_addr == INADDR_ANY)
+ inp->inp_laddr = ti->ti_dst;
+ if (in_pcbconnect(inp, am)) {
+ inp->inp_laddr = laddr;
+ (void) m_free(am);
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 */
goto drop;
}
- tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2;
+ if (om) {
+ tcp_dooptions(tp, om, ti);
+ om = 0;
+ }
+ 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;
+ dropsocket = 0; /* committed to socket */
+ tcpstat.tcps_accepts++;
goto trimthenstep6;
+ }
/*
* If the state is SYN_SENT:
*/
case TCPS_SYN_SENT:
if ((tiflags & TH_ACK) &&
-/* this should be SEQ_LT; is SEQ_LEQ for BBN vax TCP only */
- (SEQ_LT(ti->ti_ack, tp->iss) ||
+ (SEQ_LEQ(ti->ti_ack, tp->iss) ||
SEQ_GT(ti->ti_ack, tp->snd_max)))
goto dropwithreset;
if (tiflags & TH_RST) {
if (tiflags & TH_ACK)
- tcp_drop(tp, ECONNREFUSED);
+ tp = tcp_drop(tp, ECONNREFUSED);
goto drop;
}
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 (so->so_options & SO_ACCEPTCONN)
- so->so_state |= SS_CONNAWAITING;
+ 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));
(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:
/*
todrop = ti->ti_len - tp->rcv_wnd;
m_adj(m, -todrop);
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;
}
/*
* States other than LISTEN or SYN_SENT.
* First check that at least some bytes of segment are within
- * receive window.
+ * 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) {
+#ifdef TCP_COMPAT_42
+ /*
+ * Don't toss RST in response to 4.2-style keepalive.
+ */
+ if (ti->ti_seq == tp->rcv_nxt - 1 && tiflags & TH_RST)
+ goto do_rst;
+#endif
+ tcpstat.tcps_rcvduppack++;
+ tcpstat.tcps_rcvdupbyte += ti->ti_len;
+ todrop = ti->ti_len;
+ tiflags &= ~TH_FIN;
+ tp->t_flags |= TF_ACKNOW;
+ } 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 (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 new data is received on a connection after the
+ * user processes are gone, then RST the other end.
*/
- if (tp->rcv_nxt != ti->ti_seq)
+ if ((so->so_state & SS_NOFDREF) &&
+ tp->t_state > TCPS_CLOSE_WAIT && ti->ti_len) {
+ tp = tcp_close(tp);
+ tcpstat.tcps_rcvafterclose++;
+ goto dropwithreset;
+ }
+ if (tp->rcv_nxt != ti->ti_seq) {
+ tcpstat.tcps_rcvpackafterwin++;
+ tcpstat.tcps_rcvbyteafterwin += ti->ti_len;
goto dropafterack;
- if (ti->ti_len > 0) {
- 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.
- */
- if (SEQ_GT(tp->rcv_nxt, ti->ti_seq)) {
- todrop = tp->rcv_nxt - ti->ti_seq;
- 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)
- goto dropafterack;
- m_adj(m, todrop);
- ti->ti_seq += todrop;
- ti->ti_len -= todrop;
- if (ti->ti_urp > todrop)
- ti->ti_urp -= todrop;
+ if (ti->ti_len > 0) {
+ if (ti->ti_len == 1)
+ tcpstat.tcps_rcvwinprobe++;
else {
- tiflags &= ~TH_URG;
- /* ti->ti_flags &= ~TH_URG; */
- /* ti->ti_urp = 0; */
+ tcpstat.tcps_rcvpackafterwin++;
+ tcpstat.tcps_rcvbyteafterwin += ti->ti_len;
}
- /* tiflags &= ~TH_SYN; */
- /* ti->ti_flags &= ~TH_SYN; */
+ m_adj(m, ti->ti_len);
+ ti->ti_len = 0;
+ tiflags &= ~(TH_PUSH|TH_FIN);
}
+ } else {
/*
* If segment ends after window, drop trailing data
* (and PUSH and FIN); if nothing left, just ACK.
*/
- if (SEQ_GT(ti->ti_seq+ti->ti_len, tp->rcv_nxt+tp->rcv_wnd)) {
- todrop =
- ti->ti_seq+ti->ti_len - (tp->rcv_nxt+tp->rcv_wnd);
- if (todrop > ti->ti_len)
+ todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd);
+ if (todrop > 0) {
+ if (todrop >= 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 (todrop == 1)
+ tcpstat.tcps_rcvwinprobe++;
+ else {
+ tcpstat.tcps_rcvpackafterwin++;
+ tcpstat.tcps_rcvbyteafterwin += ti->ti_len;
+ }
goto dropafterack;
+ }
+ tcpstat.tcps_rcvpackafterwin++;
+ tcpstat.tcps_rcvbyteafterwin += todrop;
m_adj(m, -todrop);
ti->ti_len -= todrop;
- ti->ti_flags &= ~(TH_PUSH|TH_FIN);
+ tiflags &= ~(TH_PUSH|TH_FIN);
}
}
+#ifdef TCP_COMPAT_42
+do_rst:
+#endif
/*
* If the RST bit is set examine the state:
* SYN_RECEIVED STATE:
if (tiflags&TH_RST) switch (tp->t_state) {
case TCPS_SYN_RECEIVED:
- if (inp->inp_socket->so_options & SO_ACCEPTCONN) {
- /* a miniature tcp_close, but invisible to user */
- (void) m_free(dtom(tp->t_template));
- (void) m_free(dtom(tp));
- inp->inp_ppcb = 0;
- tp = tcp_newtcpcb(inp);
- tp->t_state = TCPS_LISTEN;
- goto drop;
- }
- tcp_drop(tp, ECONNREFUSED);
+ tp = tcp_drop(tp, ECONNREFUSED);
goto drop;
case TCPS_ESTABLISHED:
case TCPS_FIN_WAIT_1:
case TCPS_FIN_WAIT_2:
case TCPS_CLOSE_WAIT:
- tcp_drop(tp, ECONNRESET);
+ tp = tcp_drop(tp, ECONNRESET);
goto drop;
case TCPS_CLOSING:
case TCPS_LAST_ACK:
case TCPS_TIME_WAIT:
- tcp_close(tp);
+ tp = tcp_close(tp);
goto drop;
}
* error and we send an RST and drop the connection.
*/
if (tiflags & TH_SYN) {
- tcp_drop(tp, ECONNRESET);
+ tp = tcp_drop(tp, ECONNRESET);
goto dropwithreset;
}
/*
* 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;
- if (so->so_options & SO_ACCEPTCONN)
- so->so_state |= SS_CONNAWAITING;
+ tcpstat.tcps_connects++;
soisconnected(so);
tp->t_state = TCPS_ESTABLISHED;
+ 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;
- 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);
+ 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)) {
+ 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.
+ */
+ tp->t_rtt--;
+ delta = tp->t_rtt - (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 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;
+ 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.
+ * 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).
+ */
+ {
+ 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, 65535); /* XXX */
}
if (acked > so->so_snd.sb_cc) {
- sbdrop(&so->so_snd, so->so_snd.sb_cc);
tp->snd_wnd -= so->so_snd.sb_cc;
+ sbdrop(&so->so_snd, (int)so->so_snd.sb_cc);
+ ourfinisacked = 1;
} else {
- sbdrop(&so->so_snd.sb_cc, acked);
+ sbdrop(&so->so_snd, acked);
tp->snd_wnd -= acked;
- acked = 0;
+ ourfinisacked = 0;
}
- if (so->so_snd.sb_flags & SB_WAIT)
+ if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel)
sowwakeup(so);
tp->snd_una = ti->ti_ack;
if (SEQ_LT(tp->snd_nxt, tp->snd_una))
tp->snd_nxt = tp->snd_una;
- /*
- * If transmit timer is running and timed sequence
- * number was acked, update smoothed round trip time.
- */
- 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;
- tp->t_rtt = 0;
- }
-
switch (tp->t_state) {
/*
* then enter FIN_WAIT_2.
*/
case TCPS_FIN_WAIT_1:
- if (ourfinisacked)
+ if (ourfinisacked) {
+ /*
+ * If we can't receive any more
+ * data, then closing user can proceed.
+ * Starting the timer is contrary to the
+ * specification, but if we don't get a FIN
+ * we'll hang forever.
+ */
+ if (so->so_state & SS_CANTRCVMORE) {
+ soisdisconnected(so);
+ tp->t_timer[TCPT_2MSL] = TCPTV_MAXIDLE;
+ }
tp->t_state = TCPS_FIN_WAIT_2;
+ }
break;
/*
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)
- tcp_close(tp);
- goto drop;
+ if (ourfinisacked) {
+ tp = tcp_close(tp);
+ 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)) {
-/*
-printf("wl1 %x seq %x wl2 %x ack %x win %x wnd %x\n", tp->snd_wl1, ti->ti_seq, 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 > 0)
- tp->t_timer[TCPT_PERSIST] = 0;
+ if (tp->snd_wnd > tp->max_sndwnd)
+ tp->max_sndwnd = tp->snd_wnd;
+ needoutput = 1;
}
/*
- * If an URG bit is set in the segment and is greater than the
- * current known urgent pointer, then signal the user that the
- * remote side has out of band data. This should not happen
- * 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.
+ * Process segments with URG.
*/
- if ((tiflags & TH_URG) == 0 && TCPS_HAVERCVDFIN(tp->t_state) == 0)
- if (SEQ_GT(ti->ti_urp, tp->rcv_up)) {
- tp->rcv_up = ti->ti_urp;
-#if 0
- sohasoutofband(so); /* XXX */
-#endif
+ if ((tiflags & TH_URG) && ti->ti_urp &&
+ TCPS_HAVERCVDFIN(tp->t_state) == 0) {
+ /*
+ * 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 + so->so_rcv.sb_cc > SB_MAX) {
+ ti->ti_urp = 0; /* XXX */
+ tiflags &= ~TH_URG; /* XXX */
+ goto dodata; /* XXX */
+ }
+ /*
+ * If this segment advances the known urgent pointer,
+ * then mark the data stream. This should not happen
+ * 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;
+ so->so_oobmark = so->so_rcv.sb_cc +
+ (tp->rcv_up - tp->rcv_nxt) - 1;
+ if (so->so_oobmark == 0)
+ so->so_state |= SS_RCVATMARK;
+ sohasoutofband(so);
+ tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA);
}
+ /*
+ * Remove out of band data so doesn't get presented to user.
+ * This can happen independent of advancing the URG pointer,
+ * 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 &&
+ (so->so_options & SO_OOBINLINE) == 0)
+ tcp_pulloutofband(so, ti);
+ } 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) {
- off += sizeof (struct ip); /* drop IP header */
- m->m_off += off;
- m->m_len -= off;
- tiflags = tcp_reass(tp, ti);
-{ extern tcpdelack;
-if (tcpdelack) tp->t_flags |= TF_DELACK; else
- tp->t_flags |= TF_ACKNOW; /* XXX TF_DELACK */
-}
+ 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.
*/
- tcp_output(tp);
+ if (needoutput || (tp->t_flags & TF_ACKNOW))
+ (void) tcp_output(tp);
return;
dropafterack:
/*
- * Generate an ACK dropping incoming segment.
- * Make ACK reflect our state.
+ * Generate an ACK dropping incoming segment if it occupies
+ * sequence space, where the ACK reflects our state.
*/
if (tiflags & TH_RST)
goto drop;
- 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:
+ if (om) {
+ (void) m_free(om);
+ om = 0;
+ }
/*
* 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) || in_broadcast(ti->ti_dst))
goto drop;
if (tiflags & TH_ACK)
tcp_respond(tp, ti, (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, TH_RST|TH_ACK);
+ tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0,
+ TH_RST|TH_ACK);
}
+ /* destroy temporarily created socket */
+ if (dropsocket)
+ (void) soabort(so);
return;
drop:
+ if (om)
+ (void) m_free(om);
/*
* Drop space held by incoming segment and return.
*/
+ if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
+ tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0);
m_freem(m);
+ /* destroy temporarily created socket */
+ if (dropsocket)
+ (void) soabort(so);
return;
}
-/*
- * Insert segment ti into reassembly queue of tcp with
- * control block tp. Return TH_FIN if reassembly now includes
- * a segment with FIN.
- */
-tcp_reass(tp, ti)
- register struct tcpcb *tp;
- register struct tcpiphdr *ti;
+tcp_dooptions(tp, om, ti)
+ struct tcpcb *tp;
+ struct mbuf *om;
+ struct tcpiphdr *ti;
{
- register struct tcpiphdr *q;
- struct socket *so = tp->t_inpcb->inp_socket;
- struct mbuf *m;
- int flags;
-COUNT(TCP_REASS);
+ register u_char *cp;
+ int opt, optlen, cnt;
- /*
- * Call with ti==0 after become established to
- * force pre-ESTABLISHED data up to user socket.
- */
- if (ti == 0)
- goto present;
+ cp = mtod(om, u_char *);
+ cnt = om->m_len;
+ for (; cnt > 0; cnt -= optlen, cp += optlen) {
+ opt = cp[0];
+ if (opt == TCPOPT_EOL)
+ break;
+ if (opt == TCPOPT_NOP)
+ optlen = 1;
+ else {
+ optlen = cp[1];
+ if (optlen <= 0)
+ break;
+ }
+ switch (opt) {
- /*
- * Find a segment which begins after this one does.
- */
- for (q = tp->seg_next; q != (struct tcpiphdr *)tp;
- q = (struct tcpiphdr *)q->ti_next)
- if (SEQ_GT(q->ti_seq, ti->ti_seq))
+ default:
break;
- /*
- * If there is a preceding segment, it may provide some of
- * our data already. If so, drop the data from the incoming
- * segment. If it provides all of our data, drop us.
- */
- if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) {
- register int i;
- q = (struct tcpiphdr *)(q->ti_prev);
- /* 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)
- goto drop;
- m_adj(dtom(tp), i);
- ti->ti_len -= i;
- ti->ti_seq += i;
+ case TCPOPT_MAXSEG:
+ if (optlen != 4)
+ continue;
+ if (!(ti->ti_flags & TH_SYN))
+ 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));
+ break;
}
- q = (struct tcpiphdr *)(q->ti_next);
}
+ (void) m_free(om);
+}
- /*
- * While we overlap succeeding segments trim them or,
- * if they are completely covered, dequeue them.
- */
- while (q != (struct tcpiphdr *)tp &&
- SEQ_GT(ti->ti_seq + ti->ti_len, q->ti_seq)) {
- register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq;
- if (i < q->ti_len) {
- q->ti_len -= i;
- m_adj(dtom(q), i);
+/*
+ * Pull out of band byte out of a segment so
+ * it doesn't appear in the user's data queue.
+ * It is still reflected in the segment length for
+ * sequencing purposes.
+ */
+tcp_pulloutofband(so, ti)
+ struct socket *so;
+ struct tcpiphdr *ti;
+{
+ register struct mbuf *m;
+ int cnt = ti->ti_urp - 1;
+
+ m = dtom(ti);
+ while (cnt >= 0) {
+ if (m->m_len > cnt) {
+ char *cp = mtod(m, caddr_t) + cnt;
+ struct tcpcb *tp = sototcpcb(so);
+
+ tp->t_iobc = *cp;
+ tp->t_oobflags |= TCPOOB_HAVEDATA;
+ bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1));
+ m->m_len--;
+ return;
+ }
+ cnt -= m->m_len;
+ m = m->m_next;
+ if (m == 0)
break;
+ }
+ panic("tcp_pulloutofband");
+}
+
+/*
+ * 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 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.
+ */
+tcp_mss(tp)
+ register struct tcpcb *tp;
+{
+ struct route *ro;
+ struct ifnet *ifp;
+ int mss;
+ struct inpcb *inp;
+
+ inp = tp->t_inpcb;
+ ro = &inp->inp_route;
+ if ((ro->ro_rt == (struct rtentry *)0) ||
+ (ifp = ro->ro_rt->rt_ifp) == (struct ifnet *)0) {
+ /* No route yet, so try to acquire one */
+ if (inp->inp_faddr.s_addr != INADDR_ANY) {
+ ro->ro_dst.sa_family = AF_INET;
+ ((struct sockaddr_in *) &ro->ro_dst)->sin_addr =
+ inp->inp_faddr;
+ rtalloc(ro);
}
- q = (struct tcpiphdr *)q->ti_next;
- m_freem(dtom(q->ti_prev));
- remque(q->ti_prev);
+ if ((ro->ro_rt == 0) || (ifp = ro->ro_rt->rt_ifp) == 0)
+ return (TCP_MSS);
}
- /*
- * Stick new segment in its place.
- */
- insque(ti, q->ti_prev);
+ mss = ifp->if_mtu - sizeof(struct tcpiphdr);
+#if (MCLBYTES & (MCLBYTES - 1)) == 0
+ if (mss > MCLBYTES)
+ mss &= ~(MCLBYTES-1);
+#else
+ if (mss > MCLBYTES)
+ mss = mss / MCLBYTES * MCLBYTES;
+#endif
+ if (in_localaddr(inp->inp_faddr))
+ return (mss);
-present:
- /*
- * Present data to user, advancing rcv_nxt through
- * completed sequence space.
- */
- if (TCPS_HAVERCVDSYN(tp->t_state) == 0)
- return (0);
- ti = tp->seg_next;
- if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt)
- return (0);
- if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len)
- return (0);
- do {
- tp->rcv_nxt += ti->ti_len;
- flags = ti->ti_flags & TH_FIN;
- remque(ti);
- m = dtom(ti);
- ti = (struct tcpiphdr *)ti->ti_next;
- if (so->so_state & SS_CANTRCVMORE)
- (void) m_freem(m);
- else
- sbappend(&so->so_rcv, m);
- } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt);
- sorwakeup(so);
- return (flags);
-drop:
- m_freem(dtom(ti));
- return (0);
+ mss = MIN(mss, TCP_MSS);
+ tp->snd_cwnd = mss;
+ return (mss);
}