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ckcfn2.c
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/* C K C F N 2 -- System-independent Kermit protocol support functions... */
/* ...Part 2 (continued from ckcfns.c) */
/*
Author: Frank da Cruz <[email protected]>,
Columbia University Academic Information Systems, New York City.
Copyright (C) 1985, 2022,
Trustees of Columbia University in the City of New York.
All rights reserved. See the C-Kermit COPYING.TXT file or the
copyright text in the ckcmai.c module for disclaimer and permissions.
Last update: Fri Sep 23 15:23:24 2022 (CR -> CK_CR)
*/
/*
Note -- if you change this file, please amend the version number and date at
the top of ckcfns.c accordingly.
*/
#include "ckcsym.h" /* Compilation options */
#include "ckcdeb.h" /* Debugging and other symbols */
#include "ckcasc.h" /* ASCII symbols */
#include "ckcker.h" /* Kermit symbols */
#include "ckcxla.h" /* Translation */
#include "ckcnet.h" /* IKS and VMS #define TCPSOCKET */
#ifdef TCPSOCKET /* For TELNET business in spack() */
extern int tn_nlm, ttnproto, tn_b_nlm;
#endif /* TCPSOCKET */
extern int parity, network, local, interrupted, fatalio, wasclosed;
int kstartactive = 0; /* Flag for kstart() in a packet */
static CHAR p_tbl[] = { /* Even parity table for dopar(). */
(CHAR) '\000', /* ANSI C casts '\ooo' constants */
(CHAR) '\201', /* to signed char, so we have to */
(CHAR) '\202', /* cast back to unsigned char... */
(CHAR) '\003',
(CHAR) '\204',
(CHAR) '\005',
(CHAR) '\006',
(CHAR) '\207',
(CHAR) '\210',
(CHAR) '\011',
(CHAR) '\012',
(CHAR) '\213',
(CHAR) '\014',
(CHAR) '\215',
(CHAR) '\216',
(CHAR) '\017',
(CHAR) '\220',
(CHAR) '\021',
(CHAR) '\022',
(CHAR) '\223',
(CHAR) '\024',
(CHAR) '\225',
(CHAR) '\226',
(CHAR) '\027',
(CHAR) '\030',
(CHAR) '\231',
(CHAR) '\232',
(CHAR) '\033',
(CHAR) '\234',
(CHAR) '\035',
(CHAR) '\036',
(CHAR) '\237',
(CHAR) '\240',
(CHAR) '\041',
(CHAR) '\042',
(CHAR) '\243',
(CHAR) '\044',
(CHAR) '\245',
(CHAR) '\246',
(CHAR) '\047',
(CHAR) '\050',
(CHAR) '\251',
(CHAR) '\252',
(CHAR) '\053',
(CHAR) '\254',
(CHAR) '\055',
(CHAR) '\056',
(CHAR) '\257',
(CHAR) '\060',
(CHAR) '\261',
(CHAR) '\262',
(CHAR) '\063',
(CHAR) '\264',
(CHAR) '\065',
(CHAR) '\066',
(CHAR) '\267',
(CHAR) '\270',
(CHAR) '\071',
(CHAR) '\072',
(CHAR) '\273',
(CHAR) '\074',
(CHAR) '\275',
(CHAR) '\276',
(CHAR) '\077',
(CHAR) '\300',
(CHAR) '\101',
(CHAR) '\102',
(CHAR) '\303',
(CHAR) '\104',
(CHAR) '\305',
(CHAR) '\306',
(CHAR) '\107',
(CHAR) '\110',
(CHAR) '\311',
(CHAR) '\312',
(CHAR) '\113',
(CHAR) '\314',
(CHAR) '\115',
(CHAR) '\116',
(CHAR) '\317',
(CHAR) '\120',
(CHAR) '\321',
(CHAR) '\322',
(CHAR) '\123',
(CHAR) '\324',
(CHAR) '\125',
(CHAR) '\126',
(CHAR) '\327',
(CHAR) '\330',
(CHAR) '\131',
(CHAR) '\132',
(CHAR) '\333',
(CHAR) '\134',
(CHAR) '\335',
(CHAR) '\336',
(CHAR) '\137',
(CHAR) '\140',
(CHAR) '\341',
(CHAR) '\342',
(CHAR) '\143',
(CHAR) '\344',
(CHAR) '\145',
(CHAR) '\146',
(CHAR) '\347',
(CHAR) '\350',
(CHAR) '\151',
(CHAR) '\152',
(CHAR) '\353',
(CHAR) '\154',
(CHAR) '\355',
(CHAR) '\356',
(CHAR) '\157',
(CHAR) '\360',
(CHAR) '\161',
(CHAR) '\162',
(CHAR) '\363',
(CHAR) '\164',
(CHAR) '\365',
(CHAR) '\366',
(CHAR) '\167',
(CHAR) '\170',
(CHAR) '\371',
(CHAR) '\372',
(CHAR) '\173',
(CHAR) '\374',
(CHAR) '\175',
(CHAR) '\176',
(CHAR) '\377'
};
/* D O P A R -- Add an appropriate parity bit to a character */
CHAR
#ifdef CK_ANSIC
dopar(register CHAR ch)
#else
dopar(ch) register CHAR ch;
#endif /* CK_ANSIC */
{
register unsigned int a;
if (!parity
#ifdef TCPSOCKET
|| (network && (ttnproto == NP_TELNET) && (TELOPT_ME(TELOPT_BINARY)))
#ifndef NOXFER
|| (!local && sstelnet) /* TELNET BINARY MODE */
#endif /* NOXFER */
#endif /* TCPSOCKET */
) return((CHAR) (ch & 255)); else a = ch & 127;
switch (parity) {
case 'e': return(p_tbl[a]); /* Even */
case 'm': return((CHAR) (a | 128)); /* Mark */
case 'o': return((CHAR) (p_tbl[a] ^ 128)); /* Odd */
case 's': return((CHAR) a); /* Space */
default: return((CHAR) a); /* Something illegal */
}
}
#ifndef NOXFER /* Rest of this file... */
#define NEWDPL /* New dynamic packet length method */
#ifdef VMS
extern int batch;
#else
extern int backgrd;
#endif /* VMS */
#ifdef DYNAMIC
extern struct pktinfo *s_pkt; /* array of pktinfo structures */
extern struct pktinfo *r_pkt; /* array of pktinfo structures */
#else
extern struct pktinfo s_pkt[]; /* array of pktinfo structures */
extern struct pktinfo r_pkt[]; /* array of pktinfo structures */
#endif /* DYNAMIC */
extern int sseqtbl[], rseqtbl[], sbufuse[], sacktbl[], wslots, winlo, wslotn,
sbufnum, rbufnum, pktpaus, reliable;
#ifdef STREAMING
static int dontsend = 0;
extern int streaming;
#endif /* STREAMING */
extern int ttprty; /* from ck*tio.c */
extern int autopar;
extern int spsiz, spmax, rpsiz, timint, timef, npad, bestlen, maxsend;
extern int rpt, rptq, rptflg, capas, spsizf, en_fin, tsecs, flow;
extern int pktnum, sndtyp, rcvtyp, bctr, bctu, bctf, bctl, rsn, rln, maxtry;
extern int size, osize, maxsize, spktl, rpktl, nfils, stdouf, fsecs;
extern int turn, turnch, displa, pktlog, seslog, xflg, mypadn;
extern int hcflg, server, cxseen, czseen, discard, slostart;
extern int nakstate, quiet, success, xitsta, what, filestatus;
extern int spackets, rpackets, timeouts, retrans, crunched, urpsiz;
extern int carrier, fdispla, srvidl;
#ifdef GFTIMER
extern CKFLOAT fptsecs, fpfsecs, fpxfsecs;
#endif /* GFTIMER */
extern long filcnt, filrej, speed, filcps, tfcps;
extern CK_OFF_T ffc, flci, flco, tlci, tlco, tfc;
extern char *cmarg, filnam[];
extern CHAR padch, mypadc, eol, seol, ctlq, sstate;
extern CHAR *recpkt, *data, myinit[];
extern CHAR *srvptr, stchr, mystch, *rdatap;
extern CHAR padbuf[];
extern CHAR * epktmsg;
extern int epktrcvd, epktsent;
#ifdef OS2 /* AUTODOWNLOAD parameters */
extern int adl_kmode, adl_zmode; /* Match Packet to signal download */
extern char * adl_kstr; /* KERMIT Download String */
extern char * adl_zstr; /* ZMODEM Download String */
#endif /* OS2 */
#ifdef CK_AUTODL
CHAR ksbuf[96] = { NUL, NUL }; /* Autodownload "Kermit Start" buf */
#endif /* CK_AUTODL */
int numerrs = 0; /* Number of packet errors so far */
int rcvtimo = 0; /* Timeout for receiving a packet */
int idletmo = 0; /* Flag for idle timeout */
long filcps = 0L; /* CPS most recent file transferred */
long tfcps = 0L; /* CPS most recent transaction */
long xfsecs = 0L; /* Elapsed time for most recent file */
#ifdef GFTIMER
CKFLOAT fpxfsecs = 0.0; /* Ditto, but floating point */
#endif /* GFTIMER */
#ifdef CK_TIMERS
int rrttbl[64], srttbl[64]; /* Packet timestamp tables */
extern int rttflg;
#define RTT_SCALE 1000
long
rttsamples, /* Round trip time samples */
rttdelay, /* RTT delay */
pktintvl, /* Interpacket arrival time */
rttvariance, /* RTT variance */
rttstddev; /* RTT standard deviation */
#endif /* CK_TIMERS */
/* CRC generation tables */
long crcta[16] = { 0L, 010201L, 020402L, 030603L, 041004L,
051205L, 061406L, 071607L, 0102010L, 0112211L, 0122412L, 0132613L, 0143014L,
0153215L, 0163416L, 0173617L
};
long crctb[16] = { 0L, 010611L, 021422L, 031233L, 043044L,
053655L, 062466L, 072277L, 0106110L, 0116701L, 0127532L, 0137323L, 0145154L,
0155745L, 0164576L, 0174367L
};
#ifdef CK_TIMERS
/*
Round-trip timer calculations adapted from Tim Kientzle's article,
"Improving Kermit Performance", Dr Dobb's Journal, February 1996.
*/
/* R T T I N I T -- Initialize timers at start of transaction */
VOID
rttinit() { /* Initialize round-trip timing */
int i;
if (timint == 0)
return;
rttsamples = 0L; /* Samples (packets) */
rttvariance = 0L; /* Variance in delay */
rttdelay = (long) timint * RTT_SCALE; /* Delay */
pktintvl = (long) timint * RTT_SCALE; /* Delay */
rttstddev = (long) timint * RTT_SCALE; /* Standard deviation of delay */
/* Tables of timestamps indexed by packet sequence number */
for (i = 0; i < 64; i++) {
rrttbl[i] = -1; /* Time each packet was received */
srttbl[i] = -1; /* Time each packet was sent */
}
rcvtimo = timint; /* Initial timeout is what user said */
}
/* G E T R T T -- Get packet round trip time */
/*
Call with nakstate == 0 if file sender, nonzero if receiver,
and n == packet sequence number of the packet we just received.
Returns:
-1 on failure with rcvtimo set to timint (what the user said), or:
0 on success with rcvtimo set to dynamically calculated value:
1 <= rcvtimo <= timint * 3.
*/
int
getrtt(nakstate, n) int nakstate, n; {
extern int mintime, maxtime;
static int prevz = 0, prevr = 0;
int x, y, yy, z = 0, zz = 0; /* How long did it take to get here? */
rcvtimo = timint; /* Default timeout is what user said */
if (timint == 0) /* We're not timing out. */
return(0);
if (!rttflg) /* Not supposed to be doing this? */
return(-1); /* So don't */
if (!RTT_SCALE) /* Paranoia... */
return(-1);
/* rtimer() (reset timer) is not called until 1st data packet */
#ifdef GFTIMER
/* rftimer(); */
#endif /* GFTIMER */
/* S (F [ A ] D* Z)* B */
/* NOTE: we calculate both the round-trip time AND the packet */
/* arrival rate. We don't use the RTT for anything, we just display it. */
/* Timeouts are based on the packet arrival rate. */
if (spackets > 3) { /* Don't start till 4th packet */
if (nakstate) { /* File receiver */
x = rrttbl[n]; /* Time when I got packet n */
y = rrttbl[n > 0 ? n - 1 : 63]; /* Time when I got packet n-1 */
yy = srttbl[n > 0 ? n - 1 : 63]; /* Time when I sent ACK(n-1) */
if (x > -1 && y > -1) { /* Be careful */
z = x - y; /* Packet rate */
zz = x - yy; /* Round trip time */
z++; /* So sender & receiver differ */
debug(F101,"RTT RECV","",z);
} else { /* This shouldn't happen */
debug(F101,"RTT RECV ERROR spackets","",spackets);
debug(F101,"RTT RECV ERROR sequence","",n);
return(-1);
}
} else { /* File sender */
x = rrttbl[n]; /* Time when I got ACK(n) */
y = rrttbl[n > 0 ? n - 1 : 63]; /* Time when I got packet n-1 */
yy = srttbl[n]; /* Time when I sent n */
if (x > -1 && y > -1) {
z = x - y; /* Packet rate */
zz = x - yy; /* Round trip time */
debug(F101,"RTT SEND","",z);
} else {
debug(F100,"RTT SEND ERROR","",0);
return(-1);
}
}
if (z < 1) /* For fast connections */
z = RTT_SCALE / 2; /* Convert to scale... */
else
z *= RTT_SCALE;
debug(F101,"RTT z scaled","",z);
if (zz < 1) /* For fast connections */
zz = RTT_SCALE / 2; /* Convert to scale... */
else
zz *= RTT_SCALE;
rttdelay = zz; /* Round trip time of this packet */
#ifdef COMMENT
/*
This was used in C-Kermit 7.0 (and 6.0?) but not only is it overkill,
it also can produce ridiculously long timeouts under certain conditions.
Replaced in 8.0 by a far simpler and more aggressive strategy.
*/
if (rttsamples++ == 0L) { /* First sample */
pktintvl = z;
} else { /* Subsequent samples */
long oldavg = pktintvl;
long rttdiffsq;
if (rttsamples > 30) /* Use real average for first 30 */
rttsamples = 30; /* then decaying average. */
/* Average delay, difference squared, variance, std deviation */
pktintvl += (z - pktintvl) / rttsamples;
rttdiffsq = (z - oldavg) * (z - oldavg);
rttvariance += (rttdiffsq - rttvariance) / rttsamples;
debug(F101,"RTT stddev1","",rttstddev);
if (rttstddev < 1L) /* It can be zero, in which case */
rttstddev = RTT_SCALE / 3; /* set it to something small... */
rttstddev = (rttstddev + rttvariance / rttstddev) / 2;
}
debug(F101,"RTT stddev2","",rttstddev);
debug(F101,"RTT delay ","",pktintvl);
rcvtimo = (pktintvl + (3L * rttstddev)) / RTT_SCALE + 1;
if (rpackets < 32) /* Allow for slow start */
rcvtimo += rcvtimo + 2;
else if (rpackets < 64)
rcvtimo += rcvtimo / 2 + 1;
/* On a reliable link, don't try too hard to time out. */
/* Especially on fast local network connections. */
if (server && what == W_NOTHING) /* Server command wait */
rcvtimo = rcvtimo; /* == srvtim */
else if (reliable == SET_ON && rcvtimo > 0) /* Reliable */
rcvtimo = rcvtimo +15; /* and not server command wait */
else /* Not reliable or server cmd wait */
rcvtimo = rcvtimo;
if (rcvtimo < mintime) /* Lower bound */
rcvtimo = mintime;
if (maxtime > 0) { /* User specified an upper bound */
if (rcvtimo > maxtime)
rcvtimo = maxtime;
} else if (maxtime == 0) { /* User didn't specify */
if (rcvtimo > timint * 6)
rcvtimo = timint * 6;
}
#else /* COMMENT */
#ifdef CKFLOAT
{
CKFLOAT x;
x = (CKFLOAT)(prevz + z + z) / 3.0;
rcvtimo = (int)((((CKFLOAT)x * 2.66) / RTT_SCALE) + 0.5);
debug(F101,"RTT rcvtimo (float)","",rcvtimo);
}
#else
rcvtimo = (prevz + z + z) / RTT_SCALE;
debug(F101,"RTT rcvtimo (int)","",rcvtimo);
#endif /* CKFLOAT */
#endif /* COMMENT */
zz = (rttdelay + 500) / 1000;
if (rcvtimo > (zz * 3))
rcvtimo = zz * 3;
if (rcvtimo < 1)
rcvtimo = 1;
if (mintime > 0) {
if (rcvtimo < mintime) /* Lower bound */
rcvtimo = mintime;
}
if (maxtime > 0) { /* Upper bound */
if (rcvtimo > maxtime)
rcvtimo = maxtime;
}
if (rcvtimo == (prevr - 1))
rcvtimo++;
debug(F101,"RTT final rcvtimo","",rcvtimo);
}
prevz = z;
prevr = rcvtimo;
return(0);
}
#endif /* CK_TIMERS */
/* I N P U T -- Attempt to read packet number 'pktnum'. */
/*
This is the function that feeds input to Kermit's finite state machine,
in the form of a character in the range 32-126, normally a packet type
(uppercase letter) or pseudo-packet-type (lowercase letter).
If a special start state is in effect, that state is returned as if it were
the type of an incoming packet.
*/
int
input() {
int type = 0, acktype; /* Received packet type */
int x, y, k; /* Workers */
int z, pi, nf; /* Worker, packet index, NAK flag */
int nak2ack = 0;
debug(F000,"input sstate","",sstate);
debug(F101,"input nakstate","",nakstate);
debug(F000,"input sndtyp","",sndtyp);
debug(F101,"input xitsta","",xitsta);
debug(F101,"input what","",what);
while (1) { /* Big loop... */
/*
It is ttchk()'s responsibility to tell us if the connection is broken,
and to do so instantly and nondestructively -- no blocking, etc, that would
slow down file transfer.
*/
if (ttchk() < 0) {
debug(F100,"input CONNECTION BROKEN","",0);
fatalio = 1;
return('q');
}
if (sstate != 0) { /* If a start state is in effect, */
type = sstate; /* return it like a packet type, */
sstate = 0; /* and then nullify it. */
numerrs = 0; /* (PWP) no errors so far */
return(type);
}
if (nakstate) { /* This section for file receiver. */
if (wslots > 1) { /* If we're doing windows, */
x = rseqtbl[winlo]; /* see if desired packet already in. */
debug(F101,"input winlo","",winlo);
debug(F101,"input rseqtbl[winlo]","",rseqtbl[winlo]);
if (x > -1) { /* Already there? */
if (r_pkt[x].pk_seq == winlo) { /* (double check) */
rsn = winlo; /* Yes, return its info */
debug(F101,"input return pre-stashed packet","",rsn);
dumprbuf();
rdatap = r_pkt[x].pk_adr; /* like rpack would do. */
rln = (int)strlen((char *) rdatap);
type = r_pkt[x].pk_typ;
break;
}
}
}
type = rpack(); /* Try to read a packet. */
debug(F101,"input rpack","",type);
while (type == 'e') { /* Handle echoes */
debug(F101,"input echo discarded","",type);
type = rpack();
}
#ifdef DEBUG
if (deblog) {
if (type == 'D')
debug(F011,"input type D=",(char *)rdatap,39);
else
debug(F000,"input type",(char *)rdatap,type);
}
#endif /* DEBUG */
#ifndef OLDCHKINT
if (type == 'z') {
epktrcvd = 1;
errpkt((CHAR *)"User cancelled.");
type = 'E';
break;
}
#endif /* OLDCHKINT */
if (type < -1) {
char * s;
s = (type == -2) ?
"FAILED - Interrupted" :
"FAILED - Connection lost";
xxscreen(SCR_PT,'q',0L,s);
dologend();
return('q'); /* Ctrl-C or connection lost */
}
if (type < 0) { /* Receive window full */
/* Another thing to do here would be to delete */
/* the highest packet and NAK winlo. But that */
/* shouldn't be necessary since the other Kermit */
/* should not have sent a packet outside the window. */
#ifdef COMMENT
char foo[256];
ckmakxmsg(foo,256,"Receive window full (rpack): wslots=",
ckitoa(wslots)," winlo=",ckitoa(winlo)," pktnum=",
ckitoa(pktnum), NULL,NULL,NULL,NULL,NULL,NULL);
errpkt((CHAR *)foo);
debug(F100,foo,"",0);
#else
errpkt((CHAR *)"Receive window full");
debug(F101,"rpack receive window full","",0);
debug(F101," wslots","",wslots);
debug(F101," winlo","",winlo);
debug(F101," pktnum","",pktnum);
#endif
dumprbuf();
type = 'E';
break;
}
dumprbuf();
#ifdef OLDCHKINT
if (chkint() < 0) { /* Check for console interrupts. */
errpkt((CHAR *)"User cancelled."); /* (old way) */
type = 'E';
break;
}
#endif /* OLDCHKINT */
#ifdef STREAMING
if (streaming) { /* Streaming */
if (type == 'Q' || type == 'T') { /* Errors are fatal. */
crunched++; /* For statistics */
errpkt((CHAR *)"Transmission error on reliable link.");
type = 'E';
}
}
#endif /* STREAMING */
if (type == 'E') {
debug(F101,"input got E, nakstate","",nakstate);
break; /* Error packet */
}
if (type == 'Q') { /* Crunched packet. */
crunched++;
numerrs++;
/*
Packet arrived damaged. It was most likely the packet we were expecting
next, so we send a NAK for that packet. Prior to 5A(189), we always
NAK'd winlo here, but that was bad because if two (or more) different
packets were damaged, we would keep NAKing the first one and never NAK the
other ones, which could result in a lengthy series of timeouts. Now we
NAK the oldest as-yet-unNAK'd missing packet.
*/
#ifdef CK_TIMERS
rcvtimo++; /* Stretch the timeout a little */
#endif /* CK_TIMERS */
z = (winlo + wslots) % 64; /* Search from winlo to z */
debug(F101,"ZZZ crunched z","",z);
nf = 0; /* NAK flag not set yet */
for (x = winlo; x != z; x = (x + 1) % 64) {
debug(F101,"ZZZ x","",x);
if (rseqtbl[x] > -1) /* Have I received packet x? */
continue; /* Yes, go on. */
debug(F101,"ZZZ x not recd yet","",x);
pi = sseqtbl[x]; /* No, have I NAK'd it yet? */
if (pi < 0 || s_pkt[pi].pk_rtr == 0) {
debug(F101,"ZZZ x not NAK'd yet","",x);
nack(x); /* No, NAK it now. */
nf = 1; /* Flag that I did. */
break;
}
}
if (!nf) { /* If we didn't NAK anything above, */
debug(F101,"ZZZ NAKing winlo","",winlo);
if (nack(winlo) < 0) { /* we have to NAK winlo (again) */
errpkt((CHAR *)"Too many retries."); /* Too many */
type = 'E';
break;
}
}
continue;
}
if (type == 'T') { /* Timeout */
#ifndef OS2
/* K95 does this its own way */
if (server && srvidl) {
idletmo = 1;
debug(F101,"SERVER IDLE TIMEOUT","",srvidl);
return('q');
}
#endif /* OS2 */
#ifdef CK_TIMERS
rcvtimo++; /* Stretch the timeout a little */
#endif /* CK_TIMERS */
timeouts++;
debug(F101,"input receive-state timeout, winlo","",winlo);
/* NAK only the packet at window-low */
debug(F101,"input sending NAK for winlo","",winlo);
x = ttchk();
if (x > 0) /* Don't give up if there is still */
continue; /* something to read. */
else if (x < 0) {
dologend();
fatalio = 1;
return('q'); /* Connection Lost */
}
if (nack(winlo) < 0) {
debug(F101,"input sent too many naks","",winlo);
errpkt((CHAR *)"Too many retries.");
type = 'E';
break;
} else continue;
}
if (rsn == winlo) { /* Got the packet we want, done. */
#ifdef CK_TIMERS
if (rttflg && timint) /* Dynamic round trip timers? */
getrtt(nakstate, rsn); /* yes, do it. */
else /* JHD 20100208 */
rcvtimo = timint; /* JHD 20100208 */
#endif /* CK_TIMERS */
debug(F101,"input rsn=winlo","",rsn);
break;
}
/* Got a packet out of order. */
debug(F101,"input out of sequence, rsn","",rsn);
k = rseqtbl[rsn]; /* Get window slot of this packet. */
debug(F101,"input rseqtbl[rsn]","",k);
if (k < 0) {
debug(F101,"input recv can't find index for rcvd pkt","",rsn);
/* Was "Internal error 21" */
/* This should not happen */
errpkt((CHAR *)"Sliding windows protocol error.");
type = 'E';
break;
}
y = chkwin(rsn,winlo,wslots); /* See what window it's in. */
debug(F101,"input recv chkwin","",y);
if (y == 1) { /* From previous window. */
#ifdef STREAMING
if (!streaming) /* NO RESEND IF STREAMING! */
#endif /* STREAMING */
resend(rsn); /* Resend the ACK (might have data) */
freerpkt(rsn); /* Get rid of received packet */
continue; /* Back to wait for another packet */
} else { /* In this window or out of range */
if (y < 0) /* If out of range entirely, */
freerpkt(rsn); /* release its buffer */
#ifdef STREAMING
if (streaming) { /* Streaming (this shouldn't happen) */
errpkt((CHAR *)"Sequence error on reliable link.");
type = 'E';
break;
}
#endif /* STREAMING */
/* If our receive window is full, NAK window-low */
if (rbufnum < 1) { /* Receive window full? */
if (nack(winlo) < 0) { /* No choice, must NAK winlo. */
errpkt((CHAR *)"Too many retries."); /* Too many */
type = 'E';
break;
} else continue;
}
/*
Receive window not full. This is a packet in the current window but it is
not the desired packet at winlo. So therefore there are gaps before this
packet. So we find the "lowest" unNAK'd missing packet, if any, between
winlo and this one, and NAK it. If there are no as-yet-unNAK'd missing
packets in the window, then we send nothing and go wait for another packet.
In theory, this could result in a timeout, but in practice it is likely that
the already-NAK'd missing packets are already on their way. Note, we do not
NAK ahead of ourselves, as that only creates unnecessary retransmissions.
*/
for (x = winlo; x != rsn; x = (x + 1) % 64) {
if (rseqtbl[x] > -1) /* Have I received packet x? */
continue; /* Yes, check next sequence number. */
pi = sseqtbl[x]; /* No, have I NAK'd it yet? */
if (pi < 0 || s_pkt[pi].pk_rtr == 0) {
nack(x); /* No, NAK it now. */
break;
}
}
}
/*!!!*/
} else { /* Otherwise file sender... */
#ifdef STREAMING
if (streaming && sndtyp == 'D') {
debug(F101,"STREAMING input streaming","",streaming);
debug(F000,"STREAMING input sndtyp","",sndtyp);
rsn = winlo;
type = 'Y'; /* Pretend we got an ACK */
}
#endif /* STREAMING */
if (!nak2ack) { /* NAK(n+1) = ACK(n) */
if (wslots > 1) { /* Packet at winlo already ACK'd? */
if (sacktbl[winlo]) { /* If so, */
sacktbl[winlo] = 0; /* Turn off the ACK'd flag */
winlo = (winlo + 1) % 64; /* Rotate the window */
type = 'Y'; /* And return ACK */
debug(F101,
"input send returning pre-stashed ACK","",
winlo-1);
break;
}
}
#ifdef STREAMING
if (!(streaming && sndtyp == 'D')) { /* Not streaming | data */
type = rpack(); /* Try to read an acknowledgement */
} else { /* Streaming and in Data phase */
type = 'Y'; /* Assume all is normal */
if (chkint() < 0) /* Check for console interrupts. */
type = 'z';
else if (ttchk() > 4 + bctu) /* Check for return traffic */
type = rpack();
debug(F000,"input streaming type","",type);
}
#endif /* STREAMING */
debug(F111,"input send",(char *) rdatap,(int) type);
while (type == 'e') { /* Handle echoes */
debug(F000,"echo discarded","",type);
type = rpack();
}
#ifndef OLDCHKINT
if (type == 'z') {
epktrcvd = 1;
errpkt((CHAR *)"User cancelled.");
type = 'E';
break;
}
#endif /* OLDCHKINT */
if (type < -1) {
xxscreen(SCR_PT,'q',0L,
((char *)((type == -2) ?
"Interrupted" :
"Connection lost"))
);
if (type != -2)
dologend();
return('q'); /* Ctrl-C or connection lost */
}
if (type == -1) {
#ifdef COMMENT
char foo[256];
ckmakxmsg(foo,256,
"Receive window full (error 18): wslots=",
ckitoa(wslots),
" winlo=",ckitoa(winlo)," pktnum=",
ckitoa(pktnum), NULL,NULL,NULL,NULL,NULL,NULL);
errpkt((CHAR *)foo);
debug(F100,foo,"",0);
#else
errpkt((CHAR *)"Receive window full"); /* was "internal */
debug(F101," wslots","",wslots); /* error 18" */
debug(F101," winlo","",winlo);
debug(F101," pktnum","",pktnum);
#endif /* COMMENT */
dumprbuf();
type = 'E';
break;
}
dumprbuf(); /* Debugging */
#ifdef OLDCHKINT
if (chkint() < 0) { /* Check for console interrupts. */
errpkt((CHAR *)"User cancelled.");
return(type = 'E');
}
#endif /* OLDCHKINT */
/* Got a packet */
#ifdef STREAMING
if (streaming) { /* Streaming */
if (type == 'Q' || type == 'T') { /* Errors are fatal. */
crunched++; /* For statistics */
errpkt((CHAR *)"Transmission error on reliable link.");
type = 'E';
}
}
#endif /* STREAMING */
if (type == 'E') {
debug(F101,"input send got E, nakstate","",nakstate);
break; /* Error packet */
}
if (type == 'Q') { /* Crunched packet */
crunched++; /* For statistics */
numerrs++; /* For packet resizing */
x = resend(winlo); /* Resend window-low */
if (x < 0) {
type = 'E';
errpkt((CHAR *)"Too many retries");
break;
}
continue;
}
if (type == 'T') { /* Timeout waiting for ACKs. */
timeouts++; /* Count it */
numerrs++; /* Count an error too */
debug(F101,"input send state timeout, winlo","",winlo);
/* Retransmit the oldest un-ACK'd packet. */
debug(F101,"input send resending winlo","",winlo);
if (resend(winlo) < 0) { /* Check retries */
debug(F101,"input send too many resends","",maxtry);
errpkt((CHAR *)"Too many retries");
return(type = 'E');
}
#ifdef NEWDPL
/* Reduce prevailing packet length */
x = sseqtbl[winlo]; /* Get length of packet we want ACKd */
if (x > -1) { /* Only if we have a valid index */
if (s_pkt[x].pk_typ == 'D') { /* only for D packets */
spsiz = (s_pkt[x].pk_len + 8) >> 1; /* halve it */
if (spsiz < 20) spsiz = 20; /* within reason */
debug(F101,"input T cut packet length","",spsiz);
}
}
#endif /* NEWDPL */
continue;
}
}
/* Got an actual normal packet */
nak2ack = 0; /* Unset this flag. */
y = chkwin(rsn,winlo,wslots); /* Is it in the window? */
debug(F101,"input send rsn","",rsn);
debug(F101,"input send winlo","",winlo);
debug(F101,"input send chkwin","",y);
if (type == 'Y') { /* Got an ACK */
if (y == 0) { /* In current window */
if (spackets < 4) /* Error counter doesn't count */
numerrs = 0; /* until data phase. */
sacktbl[rsn]++; /* Mark the packet as ACK'd */
x = sseqtbl[rsn]; /* Get ACK'd packet's buffer index */
debug(F101,"bestlen ack x","",x);
#ifdef NEWDPL
if (x > -1) {
acktype = s_pkt[x].pk_typ; /* Get type */
debug(F000,"bestlen ack type","",acktype);
if (acktype == 'D') { /* Adjust data packet length */
if (spsiz > bestlen) {
bestlen = spsiz;
debug(F101,"bestlen B","",bestlen);
}
#ifdef DEBUG
if (deblog) {
debug(F101,"bestlen retry","",s_pkt[x].pk_rtr);
debug(F101,"bestlen len","",s_pkt[x].pk_len);
debug(F101,"bestlen spackets","",spackets);
}
#endif /* DEBUG */
/* Set new best length */
if (s_pkt[x].pk_rtr == 0 &&
s_pkt[x].pk_len + 8 > bestlen) {
bestlen = s_pkt[x].pk_len + 8;
if (bestlen > spmax)
bestlen = spmax;
debug(F101,"bestlen A","",bestlen);
}
#ifdef DEBUG
if (deblog) {
debug(F101,"bestlen wslots","",wslots);
debug(F101,"bestlen maxsend","",maxsend);
}
#endif /* DEBUG */
/* Slow start */
if (slostart &&
(maxsend <= spmax) &&
(rpackets < 11) &&
(numerrs == 0)) {
spsiz = spsiz << 1;
debug(F101,"bestlen spsiz A","",spsiz);
/* Creep up to best length */
} else if ((spackets > 5) &&
(spsiz < bestlen - 8)) {
spsiz += (bestlen - spsiz) / 3;
debug(F101,"bestlen spsiz B","",spsiz);
/* Push the envelope */
} else if ((spackets % (wslots + 1) == 0) &&
(spackets > 6) &&
(bestlen < spmax - 8) &&
(spsiz < spmax)) {
spsiz += (spmax - bestlen) / 3;
debug(F101,"bestlen spsiz C","",spsiz);
}
/* But not too far */
if (spsiz > spmax) {
spsiz = spmax;
debug(F101,"bestlen spsiz D","",spsiz);
}
}
}
#endif /* NEWDPL */
#ifdef CK_TIMERS
if (rttflg && timint) /* If doing dynamic timers */
getrtt(nakstate, rsn); /* call routine to set it. */
else /* JHD 20100208 */
rcvtimo = timint; /* JHD 20100208 */
#endif /* CK_TIMERS */
/*
NOTE: The following statement frees the buffer of the ACK we just got.
But the upper layers still need the data, like if it's the ACK to an I,
S, F, D, Z, or just about any kind of packet. So for now, freerbuf()
deallocates the buffer, but does not erase the data or destroy the pointer
to it. There's no other single place where these receive buffers can be
correctly freed (?) ...
*/
freerpkt(rsn); /* Free the ACK's buffer */