Ultrix-3.1/sys/net/tcp_input.c
/**********************************************************************
* Copyright (c) Digital Equipment Corporation 1984, 1985, 1986. *
* All Rights Reserved. *
* Reference "/usr/src/COPYRIGHT" for applicable restrictions. *
**********************************************************************/
/*
* Copyright (c) 1982 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*
* SCCSID: @(#)tcp_input.c 3.0 (ULTRIX-11) 4/21/86
* Based on: @(#)tcp_input.c 6.11 (Berkeley) 6/8/85
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <errno.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <netinet/tcp_fsm.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/tcpip.h>
#include <netinet/tcp_debug.h>
int tcpprintfs = 0;
int tcpcksum = 1;
#ifdef TCP_DEBUG
struct tcpiphdr tcp_saveti;
#endif TCP_DEBUG
extern tcpnodelack;
struct tcpcb *tcp_newtcpcb();
/*
* TCP input routine, follows pages 65-76 of the
* protocol specification dated September, 1981 very closely.
*/
tcp_input(m0)
struct mbuf *m0;
{
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;
#ifdef TCP_DEBUG
short ostate;
#endif TCP_DEBUG
struct in_addr laddr;
int dropsocket = 0;
#ifdef pdp11
segm map;
#define return goto finishup
saveseg5(map);
#endif pdp11
/*
* 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 ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) {
tcpstat.tcps_hdrops++;
return;
}
ti = mtod(m, struct tcpiphdr *);
}
/*
* Checksum extended TCP header and data.
*/
tlen = ((struct ip *)ti)->ip_len;
len = sizeof (struct ip) + tlen;
#ifdef TCPLOOPBACK
if (tcpcksum && (ti->ti_src.s_addr != ti->ti_dst.s_addr)) {
#else TCPLOOPBACK
if (tcpcksum) {
#endif TCPLOOPBACK
ti->ti_next = ti->ti_prev = 0;
#ifdef pdp11
ti->ti_pad = 0;
#endif pdp11
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;
}
}
/*
* Check that TCP offset makes sense,
* pull out TCP options and adjust length.
*/
off = ti->ti_off << 2;
if (off < sizeof (struct tcphdr) || off > tlen) {
if (tcpprintfs)
printf("tcp off: src %x off %d\n", ti->ti_src, off);
tcpstat.tcps_badoff++;
goto drop;
}
tlen -= off;
ti->ti_len = tlen;
if (off > sizeof (struct tcphdr)) {
if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) {
tcpstat.tcps_hdrops++;
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);
#ifndef pdp11
bcopy(op, mtod(om, caddr_t), (unsigned)om->m_len);
#else pdp11
MBCOPY(m, sizeof(struct tcpiphdr), om, 0, (unsigned)om->m_len);
#endif pdp11
m->m_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.
*/
off += sizeof (struct ip);
m->m_off += off;
m->m_len -= off;
/*
* Convert TCP protocol specific fields to host format.
*/
ti->ti_seq = ntohl(ti->ti_seq);
ti->ti_ack = ntohl(ti->ti_ack);
ti->ti_win = ntohs(ti->ti_win);
ti->ti_urp = ntohs(ti->ti_urp);
/*
* Locate pcb for segment.
*/
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 (inp == 0)
goto dropwithreset;
tp = intotcpcb(inp);
if (tp == 0)
goto dropwithreset;
so = inp->inp_socket;
#ifdef TCP_DEBUG
if (so->so_options & SO_DEBUG) {
ostate = tp->t_state;
tcp_saveti = *ti;
}
#endif TCP_DEBUG
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;
tp = intotcpcb(inp);
tp->t_state = TCPS_LISTEN;
}
/*
* Segment received on connection.
* Reset idle time and keep-alive timer.
*/
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.
*/
tp->rcv_wnd = sbspace(&so->so_rcv);
if (tp->rcv_wnd < 0)
tp->rcv_wnd = 0;
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.
* 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>
* Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss.
* Fill in remote peer address fields if not previously specified.
* Enter SYN_RECEIVED state, and process any other fields of this
* segment in this state.
*/
case TCPS_LISTEN: {
#ifndef pdp11
struct mbuf *am;
#endif pdp11
register struct sockaddr_in *sin;
if (tiflags & TH_RST)
goto drop;
if (tiflags & TH_ACK)
goto dropwithreset;
if ((tiflags & TH_SYN) == 0)
goto drop;
#ifndef pdp11
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 *);
#else pdp11
MSGET(sin, struct sockaddr_in, MT_SONAME, 0, M_DONTWAIT);
if (sin == NULL)
goto drop;
#endif pdp11
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;
#ifndef pdp11
if (in_pcbconnect(inp, am))
#else pdp11
if (in_pcbconnect(inp, sin))
#endif pdp11
{
inp->inp_laddr = laddr;
#ifndef pdp11
(void) m_free(am);
#else pdp11
MSFREE(sin);
#endif pdp11
goto drop;
}
#ifndef pdp11
(void) m_free(am);
#else pdp11
MSFREE(sin);
#endif pdp11
tp->t_template = tcp_template(tp);
if (tp->t_template == 0) {
in_pcbdisconnect(inp);
dropsocket = 0; /* socket is already gone */
inp->inp_laddr = laddr;
tp = 0;
goto drop;
}
if (om) {
tcp_dooptions(tp, om, ti);
om = 0;
}
tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2;
tp->irs = ti->ti_seq;
tcp_sendseqinit(tp);
tcp_rcvseqinit(tp);
tp->t_state = TCPS_SYN_RECEIVED;
tp->t_timer[TCPT_KEEP] = TCPTV_KEEP;
dropsocket = 0; /* committed to socket */
goto trimthenstep6;
}
/*
* If the state is SYN_SENT:
* if seg contains an ACK, but not for our SYN, drop the input.
* if seg contains a RST, then drop the connection.
* if seg does not contain SYN, then drop it.
* Otherwise this is an acceptable SYN segment
* initialize tp->rcv_nxt and tp->irs
* if seg contains ack then advance tp->snd_una
* if SYN has been acked change to ESTABLISHED else SYN_RCVD state
* arrange for segment to be acked (eventually)
* continue processing rest of data/controls, beginning with URG
*/
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_GT(ti->ti_ack, tp->snd_max)))
goto dropwithreset;
if (tiflags & TH_RST) {
if (tiflags & TH_ACK)
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;
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)) {
soisconnected(so);
tp->t_state = TCPS_ESTABLISHED;
tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp));
(void) tcp_reass(tp, (struct tcpiphdr *)0);
} else
tp->t_state = TCPS_SYN_RECEIVED;
goto trimthenstep6;
trimthenstep6:
/*
* Advance ti->ti_seq to correspond to first data byte.
* If data, trim to stay within window,
* dropping FIN if necessary.
*/
ti->ti_seq++;
if (ti->ti_len > tp->rcv_wnd) {
todrop = ti->ti_len - tp->rcv_wnd;
m_adj(m, -todrop);
ti->ti_len = tp->rcv_wnd;
ti->ti_flags &= ~TH_FIN;
}
tp->snd_wl1 = ti->ti_seq - 1;
goto step6;
}
/*
* If data is 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) {
tp = tcp_close(tp);
goto dropwithreset;
}
/*
* States other than LISTEN or SYN_SENT.
* First check that at least some bytes of segment are within
* receive window.
*/
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;
}
}
/*
* 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)
goto dropafterack;
m_adj(m, -todrop);
ti->ti_len -= todrop;
ti->ti_flags &= ~(TH_PUSH|TH_FIN);
}
}
/*
* If the RST bit is set examine the state:
* SYN_RECEIVED STATE:
* If passive open, return to LISTEN state.
* If active open, inform user that connection was refused.
* ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES:
* Inform user that connection was reset, and close tcb.
* CLOSING, LAST_ACK, TIME_WAIT STATES
* Close the tcb.
*/
if (tiflags&TH_RST) switch (tp->t_state) {
case TCPS_SYN_RECEIVED:
tp = tcp_drop(tp, ECONNREFUSED);
goto drop;
case TCPS_ESTABLISHED:
case TCPS_FIN_WAIT_1:
case TCPS_FIN_WAIT_2:
case TCPS_CLOSE_WAIT:
tp = tcp_drop(tp, ECONNRESET);
goto drop;
case TCPS_CLOSING:
case TCPS_LAST_ACK:
case TCPS_TIME_WAIT:
tp = tcp_close(tp);
#ifdef TCPLOOPBACK
case TCPS_CLOSED:
#endif TCPLOOPBACK
goto drop;
}
/*
* If a SYN is in the window, then this is an
* error and we send an RST and drop the connection.
*/
if (tiflags & TH_SYN) {
tp = tcp_drop(tp, ECONNRESET);
goto dropwithreset;
}
/*
* If the ACK bit is off we drop the segment and return.
*/
if ((tiflags & TH_ACK) == 0)
goto drop;
/*
* Ack processing.
*/
switch (tp->t_state) {
/*
* In SYN_RECEIVED state if the ack ACKs our SYN then enter
* ESTABLISHED state and continue processing, othewise
* 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;
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 ... */
/*
* In ESTABLISHED state: drop duplicate ACKs; ACK out of range
* ACKs. If the ack is in the range
* tp->snd_una < ti->ti_ack <= tp->snd_max
* then advance tp->snd_una to ti->ti_ack and drop
* data from the retransmission queue. If this ACK reflects
* more up to date window information we update our window information.
*/
case TCPS_ESTABLISHED:
case TCPS_FIN_WAIT_1:
case TCPS_FIN_WAIT_2:
case TCPS_CLOSE_WAIT:
case TCPS_CLOSING:
case TCPS_LAST_ACK:
case TCPS_TIME_WAIT:
#define ourfinisacked (acked > 0)
if (SEQ_LEQ(ti->ti_ack, tp->snd_una))
break;
if (SEQ_GT(ti->ti_ack, tp->snd_max))
goto dropafterack;
acked = ti->ti_ack - 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)
#ifdef pdp11
tp->t_srtt = tp->t_rtt * 10;
#else vax
tp->t_srtt = tp->t_rtt;
#endif
else
tp->t_srtt =
#ifdef pdp11
(tcp_alpha * tp->t_srtt) / 10 +
(10 - tcp_alpha) * tp->t_rtt;
#else vax
tcp_alpha * tp->t_srtt +
(1 - tcp_alpha) * tp->t_rtt;
#endif
tp->t_rtt = 0;
}
if (ti->ti_ack == tp->snd_max)
tp->t_timer[TCPT_REXMT] = 0;
else {
TCPT_RANGESET(tp->t_timer[TCPT_REXMT],
#ifdef pdp11
(tcp_beta * tp->t_srtt)/100, TCPTV_MIN, TCPTV_MAX);
#else vax
tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX);
#endif
tp->t_rxtshift = 0;
}
/*
* When new data is acked, open the congestion window a bit.
*/
if (acked > 0)
#ifdef vax
tp->snd_cwnd = MIN(11 * tp->snd_cwnd / 10, 65535);
#else pdp11
{
/*
* We need to avoid overflow. 110% of
* anything over 59570 will be over 65535,
* so just assign, only do the calculation
* when we know it won't overflow!
*/
if (tp->snd_cwnd >= 59570)
tp->snd_cwnd = 65535;
else {
register unsigned t;
t = tp->snd_cwnd/10;
/* make sure t not 0 -- Fred 2/20/86 */
if(t == 0)
t++;
tp->snd_cwnd = t*11;
}
}
#endif
if (acked > so->so_snd.sb_cc) {
tp->snd_wnd -= so->so_snd.sb_cc;
sbdrop(&so->so_snd, so->so_snd.sb_cc);
} else {
sbdrop(&so->so_snd, acked);
tp->snd_wnd -= acked;
acked = 0;
}
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;
switch (tp->t_state) {
/*
* In FIN_WAIT_1 STATE in addition to the processing
* for the ESTABLISHED state if our FIN is now acknowledged
* then enter FIN_WAIT_2.
*/
case TCPS_FIN_WAIT_1:
if (ourfinisacked) {
/*
* If we can't receive any more
* data, then closing user can proceed.
*/
if (so->so_state & SS_CANTRCVMORE)
soisdisconnected(so);
tp->t_state = TCPS_FIN_WAIT_2;
/*
* This is contrary to the specification,
* but if we haven't gotten our FIN in
* 5 minutes, it's not forthcoming.
tp->t_timer[TCPT_2MSL] = 5 * 60 * PR_SLOWHZ;
* MUST WORRY ABOUT ONE-WAY CONNECTIONS.
*/
}
break;
/*
* In CLOSING STATE in addition to the processing for
* the ESTABLISHED state if the ACK acknowledges our FIN
* then enter the TIME-WAIT state, otherwise ignore
* the segment.
*/
case TCPS_CLOSING:
if (ourfinisacked) {
tp->t_state = TCPS_TIME_WAIT;
tcp_canceltimers(tp);
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
soisdisconnected(so);
}
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.
*/
case TCPS_LAST_ACK:
if (ourfinisacked)
tp = tcp_close(tp);
goto drop;
/*
* In TIME_WAIT state the only thing that should arrive
* is a retransmission of the remote FIN. Acknowledge
* it and restart the finack timer.
*/
case TCPS_TIME_WAIT:
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
goto dropafterack;
}
#undef ourfinisacked
}
step6:
/*
* Update window information.
*/
if (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_wnd = ti->ti_win;
tp->snd_wl1 = ti->ti_seq;
tp->snd_wl2 = ti->ti_ack;
}
/*
* Process segments with URG.
*/
if ((tiflags & TH_URG) && ti->ti_urp &&
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
/*
* This is a kludge, but if we receive 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) {
ti->ti_urp = 0; /* XXX */
tiflags &= ~TH_URG; /* XXX */
ti->ti_flags &= ~TH_URG; /* XXX */
goto badurp; /* 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.
*/
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;
}
/*
* 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)
tcp_pulloutofband(so, ti);
}
badurp: /* XXX */
/*
* Process the segment text, merging it into the TCP sequencing queue,
* and arranging for acknowledgment of receipt if necessary.
* This process logically involves adjusting tp->rcv_wnd as data
* is presented to the user (this happens in tcp_usrreq.c,
* case PRU_RCVD). If a FIN has already been received on this
* connection then we just ignore the text.
*/
if ((ti->ti_len || (tiflags&TH_FIN)) &&
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
tiflags = tcp_reass(tp, ti);
if (tcpnodelack == 0)
tp->t_flags |= TF_DELACK;
else
tp->t_flags |= TF_ACKNOW;
} else {
m_freem(m);
tiflags &= ~TH_FIN;
}
/*
* If FIN is received ACK the FIN and let the user know
* that the connection is closing.
*/
if (tiflags & TH_FIN) {
if (TCPS_HAVERCVDFIN(tp->t_state) == 0) {
socantrcvmore(so);
tp->t_flags |= TF_ACKNOW;
tp->rcv_nxt++;
}
switch (tp->t_state) {
/*
* In SYN_RECEIVED and ESTABLISHED STATES
* enter the CLOSE_WAIT state.
*/
case TCPS_SYN_RECEIVED:
case TCPS_ESTABLISHED:
tp->t_state = TCPS_CLOSE_WAIT;
break;
/*
* If still in FIN_WAIT_1 STATE FIN has not been acked so
* enter the CLOSING state.
*/
case TCPS_FIN_WAIT_1:
tp->t_state = TCPS_CLOSING;
break;
/*
* In FIN_WAIT_2 state enter the TIME_WAIT state,
* starting the time-wait timer, turning off the other
* standard timers.
*/
case TCPS_FIN_WAIT_2:
tp->t_state = TCPS_TIME_WAIT;
tcp_canceltimers(tp);
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
soisdisconnected(so);
break;
/*
* In TIME_WAIT state restart the 2 MSL time_wait timer.
*/
case TCPS_TIME_WAIT:
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
break;
}
}
#ifdef TCP_DEBUG
if (so->so_options & SO_DEBUG)
tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0);
#endif TCP_DEBUG
/*
* Return any desired output.
*/
(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)
goto drop;
#ifdef TCP_DEBUG
if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
tcp_trace(TA_RESPOND, ostate, tp, &tcp_saveti, 0);
#endif TCP_DEBUG
tcp_respond(tp, ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK);
return;
dropwithreset:
if (om) {
(void) m_free(om);
om = 0;
}
/*
* Generate a RST, dropping incoming segment.
* Make ACK acceptable to originator of segment.
*/
if (tiflags & TH_RST)
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);
}
/* 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.
*/
#ifdef TCP_DEBUG
if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0);
#endif TCP_DEBUG
m_freem(m);
/* destroy temporarily created socket */
if (dropsocket)
(void) soabort(so);
return;
#ifdef pdp11
#undef return
finishup:
restorseg5(map);
return;
#endif pdp11
}
static
tcp_dooptions(tp, om, ti)
struct tcpcb *tp;
struct mbuf *om;
struct tcpiphdr *ti;
{
register u_char *cp;
int opt, optlen, cnt;
#ifdef pdp11
MAPSAVE();
#endif
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) {
default:
break;
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;
}
}
(void) m_free(om);
#ifdef pdp11
MAPREST();
#endif
}
/*
* 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.
*/
static
tcp_pulloutofband(so, ti)
struct socket *so;
struct tcpiphdr *ti;
{
register struct mbuf *m;
int cnt = ti->ti_urp - 1;
#ifdef pdp11
MAPSAVE();
#endif
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--;
#ifdef pdp11
goto out;
#else vax
return;
#endif
}
cnt -= m->m_len;
m = m->m_next;
if (m == 0)
break;
}
panic("tcp_pulloutofband");
#ifdef pdp11
out:
MAPREST();
#endif
}
#ifdef pdp11
#define ti_mbuf ti_sum
#define DTOM(d) ( (struct mbuf *) ((d)->ti_mbuf) )
#define INSQUE(i,p) { \
struct tcpiphdr *tii; \
MSGET(tii, struct tcpiphdr, MT_HEADER, 0, M_DONTWAIT); if (tii == 0) goto drop; \
insque(tii, p); \
tii->ti_len = (i)->ti_len; tii->ti_seq = (i)->ti_seq; \
tii->ti_flags = (i)->ti_flags; tii->ti_mbuf = m0; i = tii; }
#endif
/*
* Insert segment ti into reassembly queue of tcp with
* control block tp. Return TH_FIN if reassembly now includes
* a segment with FIN.
*/
static
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;
#ifdef pdp11
struct mbuf *m0;
register struct tcpiphdr *qp;
#endif pdp11
/*
* Call with ti==0 after become established to
* force pre-ESTABLISHED data up to user socket.
*/
if (ti == 0)
goto present;
#ifdef pdp11
m0 = dtom(ti);
#endif pdp11
/*
* 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)
goto drop;
#ifndef pdp11
m_adj(dtom(ti), i);
#else pdp11
m_adj(m0, i);
#endif pdp11
ti->ti_len -= i;
ti->ti_seq += i;
}
q = (struct tcpiphdr *)(q->ti_next);
}
/*
* 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;
#ifndef pdp11
m_adj(dtom(q), i);
#else pdp11
m_adj(DTOM(q), i);
#endif pdp11
break;
}
#ifndef pdp11
q = (struct tcpiphdr *)q->ti_next;
m = dtom(q->ti_prev);
remque(q->ti_prev);
#else pdp11
qp = q;
q = (struct tcpiphdr *)q->ti_next;
m = DTOM(qp);
remque(qp);
MSFREE(qp);
#endif pdp11
m_freem(m);
}
/*
* Stick new segment in its place.
*/
#ifndef pdp11
insque(ti, q->ti_prev);
#else pdp11
INSQUE(ti, q->ti_prev);
#endif pdp11
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);
#ifndef pdp11
m = dtom(ti);
#else pdp11
m = DTOM(ti);
qp = ti;
#endif pdp11
ti = (struct tcpiphdr *)ti->ti_next;
#ifdef pdp11
MSFREE(qp);
#endif pdp11
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:
#ifndef pdp11
m_freem(dtom(ti));
#else pdp11
m_freem(m0);
#endif pdp11
return (0);
}
/*
* 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 (CLSIZE), round down to nearest pagesize
* to utilize pagesize mbufs.
* If interface pointer is unavailable, or the destination isn't local,
* use a conservative size (512 or the default IP max size),
* as we can't discover anything about intervening gateways or networks.
*
* 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);
}
if ((ro->ro_rt == 0) || (ifp = ro->ro_rt->rt_ifp) == 0)
return (TCP_MSS);
}
mss = ifp->if_mtu - sizeof(struct tcpiphdr);
#if (CLBYTES & (CLBYTES - 1)) == 0
if (mss > CLBYTES)
mss &= ~(CLBYTES-1);
#else
if (mss > CLBYTES)
mss = mss / CLBYTES * CLBYTES;
#endif
if (in_localaddr(tp->t_inpcb->inp_faddr))
return(mss);
return (MIN(mss, TCP_MSS));
}