1/*
2 * Copyright (c) 1988, 1990, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include "telnet_locl.h"
35
36RCSID("$Id: sys_bsd.c 10941 2002-04-18 16:18:43Z joda $");
37
38/*
39 * The following routines try to encapsulate what is system dependent
40 * (at least between 4.x and dos) which is used in telnet.c.
41 */
42
43int
44	tout,			/* Output file descriptor */
45	tin,			/* Input file descriptor */
46	net;
47
48struct	termios old_tc = { 0 };
49extern struct termios new_tc;
50
51# ifndef	TCSANOW
52#  ifdef TCSETS
53#   define	TCSANOW		TCSETS
54#   define	TCSADRAIN	TCSETSW
55#   define	tcgetattr(f, t) ioctl(f, TCGETS, (char *)t)
56#  else
57#   ifdef TCSETA
58#    define	TCSANOW		TCSETA
59#    define	TCSADRAIN	TCSETAW
60#    define	tcgetattr(f, t) ioctl(f, TCGETA, (char *)t)
61#   else
62#    define	TCSANOW		TIOCSETA
63#    define	TCSADRAIN	TIOCSETAW
64#    define	tcgetattr(f, t) ioctl(f, TIOCGETA, (char *)t)
65#   endif
66#  endif
67#  define	tcsetattr(f, a, t) ioctl(f, a, (char *)t)
68#  define	cfgetospeed(ptr)	((ptr)->c_cflag&CBAUD)
69#  ifdef CIBAUD
70#   define	cfgetispeed(ptr)	(((ptr)->c_cflag&CIBAUD) >> IBSHIFT)
71#  else
72#   define	cfgetispeed(ptr)	cfgetospeed(ptr)
73#  endif
74# endif /* TCSANOW */
75
76static fd_set ibits, obits, xbits;
77
78
79void
80init_sys(void)
81{
82    tout = fileno(stdout);
83    tin = fileno(stdin);
84    FD_ZERO(&ibits);
85    FD_ZERO(&obits);
86    FD_ZERO(&xbits);
87
88    errno = 0;
89}
90
91
92int
93TerminalWrite(char *buf, int n)
94{
95    return write(tout, buf, n);
96}
97
98int
99TerminalRead(unsigned char *buf, int n)
100{
101    return read(tin, buf, n);
102}
103
104/*
105 *
106 */
107
108int
109TerminalAutoFlush(void)
110{
111#if	defined(LNOFLSH)
112    int flush;
113
114    ioctl(0, TIOCLGET, (char *)&flush);
115    return !(flush&LNOFLSH);	/* if LNOFLSH, no autoflush */
116#else	/* LNOFLSH */
117    return 1;
118#endif	/* LNOFLSH */
119}
120
121/*
122 * TerminalSpecialChars()
123 *
124 * Look at an input character to see if it is a special character
125 * and decide what to do.
126 *
127 * Output:
128 *
129 *	0	Don't add this character.
130 *	1	Do add this character
131 */
132
133int
134TerminalSpecialChars(int c)
135{
136    if (c == termIntChar) {
137	intp();
138	return 0;
139    } else if (c == termQuitChar) {
140#ifdef	KLUDGELINEMODE
141	if (kludgelinemode)
142	    sendbrk();
143	else
144#endif
145	    sendabort();
146	return 0;
147    } else if (c == termEofChar) {
148	if (my_want_state_is_will(TELOPT_LINEMODE)) {
149	    sendeof();
150	    return 0;
151	}
152	return 1;
153    } else if (c == termSuspChar) {
154	sendsusp();
155	return(0);
156    } else if (c == termFlushChar) {
157	xmitAO();		/* Transmit Abort Output */
158	return 0;
159    } else if (!MODE_LOCAL_CHARS(globalmode)) {
160	if (c == termKillChar) {
161	    xmitEL();
162	    return 0;
163	} else if (c == termEraseChar) {
164	    xmitEC();		/* Transmit Erase Character */
165	    return 0;
166	}
167    }
168    return 1;
169}
170
171
172/*
173 * Flush output to the terminal
174 */
175
176void
177TerminalFlushOutput(void)
178{
179#ifdef	TIOCFLUSH
180    ioctl(fileno(stdout), TIOCFLUSH, (char *) 0);
181#else
182    ioctl(fileno(stdout), TCFLSH, (char *) 0);
183#endif
184}
185
186void
187TerminalSaveState(void)
188{
189    tcgetattr(0, &old_tc);
190
191    new_tc = old_tc;
192
193#ifndef	VDISCARD
194    termFlushChar = CONTROL('O');
195#endif
196#ifndef	VWERASE
197    termWerasChar = CONTROL('W');
198#endif
199#ifndef	VREPRINT
200    termRprntChar = CONTROL('R');
201#endif
202#ifndef	VLNEXT
203    termLiteralNextChar = CONTROL('V');
204#endif
205#ifndef	VSTART
206    termStartChar = CONTROL('Q');
207#endif
208#ifndef	VSTOP
209    termStopChar = CONTROL('S');
210#endif
211#ifndef	VSTATUS
212    termAytChar = CONTROL('T');
213#endif
214}
215
216cc_t*
217tcval(int func)
218{
219    switch(func) {
220    case SLC_IP:	return(&termIntChar);
221    case SLC_ABORT:	return(&termQuitChar);
222    case SLC_EOF:	return(&termEofChar);
223    case SLC_EC:	return(&termEraseChar);
224    case SLC_EL:	return(&termKillChar);
225    case SLC_XON:	return(&termStartChar);
226    case SLC_XOFF:	return(&termStopChar);
227    case SLC_FORW1:	return(&termForw1Char);
228    case SLC_FORW2:	return(&termForw2Char);
229# ifdef	VDISCARD
230    case SLC_AO:	return(&termFlushChar);
231# endif
232# ifdef	VSUSP
233    case SLC_SUSP:	return(&termSuspChar);
234# endif
235# ifdef	VWERASE
236    case SLC_EW:	return(&termWerasChar);
237# endif
238# ifdef	VREPRINT
239    case SLC_RP:	return(&termRprntChar);
240# endif
241# ifdef	VLNEXT
242    case SLC_LNEXT:	return(&termLiteralNextChar);
243# endif
244# ifdef	VSTATUS
245    case SLC_AYT:	return(&termAytChar);
246# endif
247
248    case SLC_SYNCH:
249    case SLC_BRK:
250    case SLC_EOR:
251    default:
252	return((cc_t *)0);
253    }
254}
255
256void
257TerminalDefaultChars(void)
258{
259    memmove(new_tc.c_cc, old_tc.c_cc, sizeof(old_tc.c_cc));
260# ifndef	VDISCARD
261    termFlushChar = CONTROL('O');
262# endif
263# ifndef	VWERASE
264    termWerasChar = CONTROL('W');
265# endif
266# ifndef	VREPRINT
267    termRprntChar = CONTROL('R');
268# endif
269# ifndef	VLNEXT
270    termLiteralNextChar = CONTROL('V');
271# endif
272# ifndef	VSTART
273    termStartChar = CONTROL('Q');
274# endif
275# ifndef	VSTOP
276    termStopChar = CONTROL('S');
277# endif
278# ifndef	VSTATUS
279    termAytChar = CONTROL('T');
280# endif
281}
282
283#ifdef notdef
284void
285TerminalRestoreState()
286{
287}
288#endif
289
290/*
291 * TerminalNewMode - set up terminal to a specific mode.
292 *	MODE_ECHO: do local terminal echo
293 *	MODE_FLOW: do local flow control
294 *	MODE_TRAPSIG: do local mapping to TELNET IAC sequences
295 *	MODE_EDIT: do local line editing
296 *
297 *	Command mode:
298 *		MODE_ECHO|MODE_EDIT|MODE_FLOW|MODE_TRAPSIG
299 *		local echo
300 *		local editing
301 *		local xon/xoff
302 *		local signal mapping
303 *
304 *	Linemode:
305 *		local/no editing
306 *	Both Linemode and Single Character mode:
307 *		local/remote echo
308 *		local/no xon/xoff
309 *		local/no signal mapping
310 */
311
312
313#ifdef	SIGTSTP
314static RETSIGTYPE susp(int);
315#endif	/* SIGTSTP */
316#ifdef	SIGINFO
317static RETSIGTYPE ayt(int);
318#endif
319
320void
321TerminalNewMode(int f)
322{
323    static int prevmode = 0;
324    struct termios tmp_tc;
325    int onoff;
326    int old;
327    cc_t esc;
328
329    globalmode = f&~MODE_FORCE;
330    if (prevmode == f)
331	return;
332
333    /*
334     * Write any outstanding data before switching modes
335     * ttyflush() returns 0 only when there is no more data
336     * left to write out, it returns -1 if it couldn't do
337     * anything at all, otherwise it returns 1 + the number
338     * of characters left to write.
339     */
340    old = ttyflush(SYNCHing|flushout);
341    if (old < 0 || old > 1) {
342	tcgetattr(tin, &tmp_tc);
343	do {
344	    /*
345	     * Wait for data to drain, then flush again.
346	     */
347	    tcsetattr(tin, TCSADRAIN, &tmp_tc);
348	    old = ttyflush(SYNCHing|flushout);
349	} while (old < 0 || old > 1);
350    }
351
352    old = prevmode;
353    prevmode = f&~MODE_FORCE;
354    tmp_tc = new_tc;
355
356    if (f&MODE_ECHO) {
357	tmp_tc.c_lflag |= ECHO;
358	tmp_tc.c_oflag |= ONLCR;
359	if (crlf)
360		tmp_tc.c_iflag |= ICRNL;
361    } else {
362	tmp_tc.c_lflag &= ~ECHO;
363	tmp_tc.c_oflag &= ~ONLCR;
364# ifdef notdef
365	if (crlf)
366		tmp_tc.c_iflag &= ~ICRNL;
367# endif
368    }
369
370    if ((f&MODE_FLOW) == 0) {
371	tmp_tc.c_iflag &= ~(IXOFF|IXON);	/* Leave the IXANY bit alone */
372    } else {
373	if (restartany < 0) {
374		tmp_tc.c_iflag |= IXOFF|IXON;	/* Leave the IXANY bit alone */
375	} else if (restartany > 0) {
376		tmp_tc.c_iflag |= IXOFF|IXON|IXANY;
377	} else {
378		tmp_tc.c_iflag |= IXOFF|IXON;
379		tmp_tc.c_iflag &= ~IXANY;
380	}
381    }
382
383    if ((f&MODE_TRAPSIG) == 0) {
384	tmp_tc.c_lflag &= ~ISIG;
385	localchars = 0;
386    } else {
387	tmp_tc.c_lflag |= ISIG;
388	localchars = 1;
389    }
390
391    if (f&MODE_EDIT) {
392	tmp_tc.c_lflag |= ICANON;
393    } else {
394	tmp_tc.c_lflag &= ~ICANON;
395	tmp_tc.c_iflag &= ~ICRNL;
396	tmp_tc.c_cc[VMIN] = 1;
397	tmp_tc.c_cc[VTIME] = 0;
398    }
399
400    if ((f&(MODE_EDIT|MODE_TRAPSIG)) == 0) {
401# ifdef VLNEXT
402	tmp_tc.c_cc[VLNEXT] = (cc_t)(_POSIX_VDISABLE);
403# endif
404    }
405
406    if (f&MODE_SOFT_TAB) {
407# ifdef	OXTABS
408	tmp_tc.c_oflag |= OXTABS;
409# endif
410# ifdef	TABDLY
411	tmp_tc.c_oflag &= ~TABDLY;
412	tmp_tc.c_oflag |= TAB3;
413# endif
414    } else {
415# ifdef	OXTABS
416	tmp_tc.c_oflag &= ~OXTABS;
417# endif
418# ifdef	TABDLY
419	tmp_tc.c_oflag &= ~TABDLY;
420# endif
421    }
422
423    if (f&MODE_LIT_ECHO) {
424# ifdef	ECHOCTL
425	tmp_tc.c_lflag &= ~ECHOCTL;
426# endif
427    } else {
428# ifdef	ECHOCTL
429	tmp_tc.c_lflag |= ECHOCTL;
430# endif
431    }
432
433    if (f == -1) {
434	onoff = 0;
435    } else {
436	if (f & MODE_INBIN)
437		tmp_tc.c_iflag &= ~ISTRIP;
438	else
439		tmp_tc.c_iflag |= ISTRIP;
440	if ((f & MODE_OUTBIN) || (f & MODE_OUT8)) {
441		tmp_tc.c_cflag &= ~(CSIZE|PARENB);
442		tmp_tc.c_cflag |= CS8;
443		if(f & MODE_OUTBIN)
444		    tmp_tc.c_oflag &= ~OPOST;
445		else
446		    tmp_tc.c_oflag |= OPOST;
447	} else {
448		tmp_tc.c_cflag &= ~(CSIZE|PARENB);
449		tmp_tc.c_cflag |= old_tc.c_cflag & (CSIZE|PARENB);
450		tmp_tc.c_oflag |= OPOST;
451	}
452	onoff = 1;
453    }
454
455    if (f != -1) {
456
457#ifdef	SIGTSTP
458	signal(SIGTSTP, susp);
459#endif	/* SIGTSTP */
460#ifdef	SIGINFO
461	signal(SIGINFO, ayt);
462#endif
463#ifdef NOKERNINFO
464	tmp_tc.c_lflag |= NOKERNINFO;
465#endif
466	/*
467	 * We don't want to process ^Y here.  It's just another
468	 * character that we'll pass on to the back end.  It has
469	 * to process it because it will be processed when the
470	 * user attempts to read it, not when we send it.
471	 */
472# ifdef	VDSUSP
473	tmp_tc.c_cc[VDSUSP] = (cc_t)(_POSIX_VDISABLE);
474# endif
475	/*
476	 * If the VEOL character is already set, then use VEOL2,
477	 * otherwise use VEOL.
478	 */
479	esc = (rlogin != _POSIX_VDISABLE) ? rlogin : escape;
480	if ((tmp_tc.c_cc[VEOL] != esc)
481# ifdef	VEOL2
482	    && (tmp_tc.c_cc[VEOL2] != esc)
483# endif
484	    ) {
485		if (tmp_tc.c_cc[VEOL] == (cc_t)(_POSIX_VDISABLE))
486		    tmp_tc.c_cc[VEOL] = esc;
487# ifdef	VEOL2
488		else if (tmp_tc.c_cc[VEOL2] == (cc_t)(_POSIX_VDISABLE))
489		    tmp_tc.c_cc[VEOL2] = esc;
490# endif
491	}
492    } else {
493        sigset_t sm;
494
495#ifdef	SIGINFO
496	signal(SIGINFO, ayt_status);
497#endif
498#ifdef	SIGTSTP
499	signal(SIGTSTP, SIG_DFL);
500	sigemptyset(&sm);
501	sigaddset(&sm, SIGTSTP);
502	sigprocmask(SIG_UNBLOCK, &sm, NULL);
503#endif	/* SIGTSTP */
504	tmp_tc = old_tc;
505    }
506    if (tcsetattr(tin, TCSADRAIN, &tmp_tc) < 0)
507	tcsetattr(tin, TCSANOW, &tmp_tc);
508
509    ioctl(tin, FIONBIO, (char *)&onoff);
510    ioctl(tout, FIONBIO, (char *)&onoff);
511
512}
513
514/*
515 * Try to guess whether speeds are "encoded" (4.2BSD) or just numeric (4.4BSD).
516 */
517#if B4800 != 4800
518#define	DECODE_BAUD
519#endif
520
521#ifdef	DECODE_BAUD
522#ifndef	B7200
523#define B7200   B4800
524#endif
525
526#ifndef	B14400
527#define B14400  B9600
528#endif
529
530#ifndef	B19200
531# define B19200 B14400
532#endif
533
534#ifndef	B28800
535#define B28800  B19200
536#endif
537
538#ifndef	B38400
539# define B38400 B28800
540#endif
541
542#ifndef B57600
543#define B57600  B38400
544#endif
545
546#ifndef B76800
547#define B76800  B57600
548#endif
549
550#ifndef B115200
551#define B115200 B76800
552#endif
553
554#ifndef B230400
555#define B230400 B115200
556#endif
557
558
559/*
560 * This code assumes that the values B0, B50, B75...
561 * are in ascending order.  They do not have to be
562 * contiguous.
563 */
564struct termspeeds {
565	long speed;
566	long value;
567} termspeeds[] = {
568	{ 0,      B0 },      { 50,    B50 },    { 75,     B75 },
569	{ 110,    B110 },    { 134,   B134 },   { 150,    B150 },
570	{ 200,    B200 },    { 300,   B300 },   { 600,    B600 },
571	{ 1200,   B1200 },   { 1800,  B1800 },  { 2400,   B2400 },
572	{ 4800,   B4800 },   { 7200,  B7200 },  { 9600,   B9600 },
573	{ 14400,  B14400 },  { 19200, B19200 }, { 28800,  B28800 },
574	{ 38400,  B38400 },  { 57600, B57600 }, { 115200, B115200 },
575	{ 230400, B230400 }, { -1,    B230400 }
576};
577#endif	/* DECODE_BAUD */
578
579void
580TerminalSpeeds(long *input_speed, long *output_speed)
581{
582#ifdef	DECODE_BAUD
583    struct termspeeds *tp;
584#endif	/* DECODE_BAUD */
585    long in, out;
586
587    out = cfgetospeed(&old_tc);
588    in = cfgetispeed(&old_tc);
589    if (in == 0)
590	in = out;
591
592#ifdef	DECODE_BAUD
593    tp = termspeeds;
594    while ((tp->speed != -1) && (tp->value < in))
595	tp++;
596    *input_speed = tp->speed;
597
598    tp = termspeeds;
599    while ((tp->speed != -1) && (tp->value < out))
600	tp++;
601    *output_speed = tp->speed;
602#else	/* DECODE_BAUD */
603	*input_speed = in;
604	*output_speed = out;
605#endif	/* DECODE_BAUD */
606}
607
608int
609TerminalWindowSize(long *rows, long *cols)
610{
611    struct winsize ws;
612
613    if (get_window_size (STDIN_FILENO, &ws) == 0) {
614	*rows = ws.ws_row;
615	*cols = ws.ws_col;
616	return 1;
617    } else
618	return 0;
619}
620
621int
622NetClose(int fd)
623{
624    return close(fd);
625}
626
627
628void
629NetNonblockingIO(int fd, int onoff)
630{
631    ioctl(fd, FIONBIO, (char *)&onoff);
632}
633
634
635/*
636 * Various signal handling routines.
637 */
638
639static RETSIGTYPE deadpeer(int),
640  intr(int), intr2(int), susp(int), sendwin(int);
641#ifdef SIGINFO
642static RETSIGTYPE ayt(int);
643#endif
644
645
646    /* ARGSUSED */
647static RETSIGTYPE
648deadpeer(int sig)
649{
650	setcommandmode();
651	longjmp(peerdied, -1);
652}
653
654int intr_happened = 0;
655int intr_waiting = 0;
656
657    /* ARGSUSED */
658static RETSIGTYPE
659intr(int sig)
660{
661    if (intr_waiting) {
662	intr_happened = 1;
663	return;
664    }
665    if (localchars) {
666	intp();
667	return;
668    }
669    setcommandmode();
670    longjmp(toplevel, -1);
671}
672
673    /* ARGSUSED */
674static RETSIGTYPE
675intr2(int sig)
676{
677    if (localchars) {
678#ifdef	KLUDGELINEMODE
679	if (kludgelinemode)
680	    sendbrk();
681	else
682#endif
683	    sendabort();
684	return;
685    }
686}
687
688#ifdef	SIGTSTP
689    /* ARGSUSED */
690static RETSIGTYPE
691susp(int sig)
692{
693    if ((rlogin != _POSIX_VDISABLE) && rlogin_susp())
694	return;
695    if (localchars)
696	sendsusp();
697}
698#endif
699
700#ifdef	SIGWINCH
701    /* ARGSUSED */
702static RETSIGTYPE
703sendwin(int sig)
704{
705    if (connected) {
706	sendnaws();
707    }
708}
709#endif
710
711#ifdef	SIGINFO
712    /* ARGSUSED */
713static RETSIGTYPE
714ayt(int sig)
715{
716    if (connected)
717	sendayt();
718    else
719	ayt_status(sig);
720}
721#endif
722
723
724void
725sys_telnet_init(void)
726{
727    signal(SIGINT, intr);
728    signal(SIGQUIT, intr2);
729    signal(SIGPIPE, deadpeer);
730#ifdef	SIGWINCH
731    signal(SIGWINCH, sendwin);
732#endif
733#ifdef	SIGTSTP
734    signal(SIGTSTP, susp);
735#endif
736#ifdef	SIGINFO
737    signal(SIGINFO, ayt);
738#endif
739
740    setconnmode(0);
741
742    NetNonblockingIO(net, 1);
743
744
745#if	defined(SO_OOBINLINE)
746    if (SetSockOpt(net, SOL_SOCKET, SO_OOBINLINE, 1) == -1)
747	perror("setsockopt (SO_OOBINLINE) (ignored)");
748#endif	/* defined(SO_OOBINLINE) */
749}
750
751/*
752 * Process rings -
753 *
754 *	This routine tries to fill up/empty our various rings.
755 *
756 *	The parameter specifies whether this is a poll operation,
757 *	or a block-until-something-happens operation.
758 *
759 *	The return value is 1 if something happened, 0 if not.
760 */
761
762int
763process_rings(int netin,
764	      int netout,
765	      int netex,
766	      int ttyin,
767	      int ttyout,
768	      int poll) /* If 0, then block until something to do */
769{
770    int c;
771		/* One wants to be a bit careful about setting returnValue
772		 * to one, since a one implies we did some useful work,
773		 * and therefore probably won't be called to block next
774		 * time (TN3270 mode only).
775		 */
776    int returnValue = 0;
777    static struct timeval TimeValue = { 0 };
778
779    if (net >= FD_SETSIZE
780	|| tout >= FD_SETSIZE
781	|| tin >= FD_SETSIZE)
782	errx (1, "fd too large");
783
784    if (netout) {
785	FD_SET(net, &obits);
786    }
787    if (ttyout) {
788	FD_SET(tout, &obits);
789    }
790    if (ttyin) {
791	FD_SET(tin, &ibits);
792    }
793    if (netin) {
794	FD_SET(net, &ibits);
795    }
796#if !defined(SO_OOBINLINE)
797    if (netex) {
798	FD_SET(net, &xbits);
799    }
800#endif
801    if ((c = select(FD_SETSIZE, &ibits, &obits, &xbits,
802			(poll == 0)? (struct timeval *)0 : &TimeValue)) < 0) {
803	if (c == -1) {
804		    /*
805		     * we can get EINTR if we are in line mode,
806		     * and the user does an escape (TSTP), or
807		     * some other signal generator.
808		     */
809	    if (errno == EINTR) {
810		return 0;
811	    }
812		    /* I don't like this, does it ever happen? */
813	    printf("sleep(5) from telnet, after select\r\n");
814	    sleep(5);
815	}
816	return 0;
817    }
818
819    /*
820     * Any urgent data?
821     */
822    if (FD_ISSET(net, &xbits)) {
823	FD_CLR(net, &xbits);
824	SYNCHing = 1;
825	ttyflush(1);	/* flush already enqueued data */
826    }
827
828    /*
829     * Something to read from the network...
830     */
831    if (FD_ISSET(net, &ibits)) {
832	int canread;
833
834	FD_CLR(net, &ibits);
835	canread = ring_empty_consecutive(&netiring);
836#if	!defined(SO_OOBINLINE)
837	    /*
838	     * In 4.2 (and some early 4.3) systems, the
839	     * OOB indication and data handling in the kernel
840	     * is such that if two separate TCP Urgent requests
841	     * come in, one byte of TCP data will be overlaid.
842	     * This is fatal for Telnet, but we try to live
843	     * with it.
844	     *
845	     * In addition, in 4.2 (and...), a special protocol
846	     * is needed to pick up the TCP Urgent data in
847	     * the correct sequence.
848	     *
849	     * What we do is:  if we think we are in urgent
850	     * mode, we look to see if we are "at the mark".
851	     * If we are, we do an OOB receive.  If we run
852	     * this twice, we will do the OOB receive twice,
853	     * but the second will fail, since the second
854	     * time we were "at the mark", but there wasn't
855	     * any data there (the kernel doesn't reset
856	     * "at the mark" until we do a normal read).
857	     * Once we've read the OOB data, we go ahead
858	     * and do normal reads.
859	     *
860	     * There is also another problem, which is that
861	     * since the OOB byte we read doesn't put us
862	     * out of OOB state, and since that byte is most
863	     * likely the TELNET DM (data mark), we would
864	     * stay in the TELNET SYNCH (SYNCHing) state.
865	     * So, clocks to the rescue.  If we've "just"
866	     * received a DM, then we test for the
867	     * presence of OOB data when the receive OOB
868	     * fails (and AFTER we did the normal mode read
869	     * to clear "at the mark").
870	     */
871	if (SYNCHing) {
872	    int atmark;
873	    static int bogus_oob = 0, first = 1;
874
875	    ioctl(net, SIOCATMARK, (char *)&atmark);
876	    if (atmark) {
877		c = recv(net, netiring.supply, canread, MSG_OOB);
878		if ((c == -1) && (errno == EINVAL)) {
879		    c = recv(net, netiring.supply, canread, 0);
880		    if (clocks.didnetreceive < clocks.gotDM) {
881			SYNCHing = stilloob();
882		    }
883		} else if (first && c > 0) {
884		    /*
885		     * Bogosity check.  Systems based on 4.2BSD
886		     * do not return an error if you do a second
887		     * recv(MSG_OOB).  So, we do one.  If it
888		     * succeeds and returns exactly the same
889		     * data, then assume that we are running
890		     * on a broken system and set the bogus_oob
891		     * flag.  (If the data was different, then
892		     * we probably got some valid new data, so
893		     * increment the count...)
894		     */
895		    int i;
896		    i = recv(net, netiring.supply + c, canread - c, MSG_OOB);
897		    if (i == c &&
898			 memcmp(netiring.supply, netiring.supply + c, i) == 0) {
899			bogus_oob = 1;
900			first = 0;
901		    } else if (i < 0) {
902			bogus_oob = 0;
903			first = 0;
904		    } else
905			c += i;
906		}
907		if (bogus_oob && c > 0) {
908		    int i;
909		    /*
910		     * Bogosity.  We have to do the read
911		     * to clear the atmark to get out of
912		     * an infinate loop.
913		     */
914		    i = read(net, netiring.supply + c, canread - c);
915		    if (i > 0)
916			c += i;
917		}
918	    } else {
919		c = recv(net, netiring.supply, canread, 0);
920	    }
921	} else {
922	    c = recv(net, netiring.supply, canread, 0);
923	}
924	settimer(didnetreceive);
925#else	/* !defined(SO_OOBINLINE) */
926	c = recv(net, (char *)netiring.supply, canread, 0);
927#endif	/* !defined(SO_OOBINLINE) */
928	if (c < 0 && errno == EWOULDBLOCK) {
929	    c = 0;
930	} else if (c <= 0) {
931	    return -1;
932	}
933	if (netdata) {
934	    Dump('<', netiring.supply, c);
935	}
936	if (c)
937	    ring_supplied(&netiring, c);
938	returnValue = 1;
939    }
940
941    /*
942     * Something to read from the tty...
943     */
944    if (FD_ISSET(tin, &ibits)) {
945	FD_CLR(tin, &ibits);
946	c = TerminalRead(ttyiring.supply, ring_empty_consecutive(&ttyiring));
947	if (c < 0 && errno == EIO)
948	    c = 0;
949	if (c < 0 && errno == EWOULDBLOCK) {
950	    c = 0;
951	} else {
952	    /* EOF detection for line mode!!!! */
953	    if ((c == 0) && MODE_LOCAL_CHARS(globalmode) && isatty(tin)) {
954			/* must be an EOF... */
955		*ttyiring.supply = termEofChar;
956		c = 1;
957	    }
958	    if (c <= 0) {
959		return -1;
960	    }
961	    if (termdata) {
962		Dump('<', ttyiring.supply, c);
963	    }
964	    ring_supplied(&ttyiring, c);
965	}
966	returnValue = 1;		/* did something useful */
967    }
968
969    if (FD_ISSET(net, &obits)) {
970	FD_CLR(net, &obits);
971	returnValue |= netflush();
972    }
973    if (FD_ISSET(tout, &obits)) {
974	FD_CLR(tout, &obits);
975	returnValue |= (ttyflush(SYNCHing|flushout) > 0);
976    }
977
978    return returnValue;
979}
980