telnetd.c revision 202212 
1/*
2 * Copyright (c) 1989, 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#if 0
35#ifndef lint
36static const char sccsid[] = "@(#)telnetd.c	8.4 (Berkeley) 5/30/95";
37#endif
38#endif
39#include <sys/cdefs.h>
40__FBSDID("$FreeBSD: head/contrib/telnet/telnetd/telnetd.c 202212 2010-01-13 18:37:42Z ed $");
41
42#include "telnetd.h"
43#include "pathnames.h"
44
45#include <sys/mman.h>
46#include <err.h>
47#include <libutil.h>
48#include <paths.h>
49#include <termcap.h>
50
51#include <arpa/inet.h>
52
53#ifdef	AUTHENTICATION
54#include <libtelnet/auth.h>
55int	auth_level = 0;
56#endif
57#ifdef	ENCRYPTION
58#include <libtelnet/encrypt.h>
59#endif
60#include <libtelnet/misc.h>
61
62char	remote_hostname[MAXHOSTNAMELEN];
63size_t	utmp_len = sizeof(remote_hostname) - 1;
64int	registerd_host_only = 0;
65
66
67/*
68 * I/O data buffers,
69 * pointers, and counters.
70 */
71char	ptyibuf[BUFSIZ], *ptyip = ptyibuf;
72char	ptyibuf2[BUFSIZ];
73
74int readstream(int, char *, int);
75void doit(struct sockaddr *);
76int terminaltypeok(char *);
77
78int	hostinfo = 1;			/* do we print login banner? */
79
80static int debug = 0;
81int keepalive = 1;
82const char *altlogin;
83
84void doit(struct sockaddr *);
85int terminaltypeok(char *);
86void startslave(char *, int, char *);
87extern void usage(void);
88static void _gettermname(void);
89
90/*
91 * The string to pass to getopt().  We do it this way so
92 * that only the actual options that we support will be
93 * passed off to getopt().
94 */
95char valid_opts[] = {
96	'd', ':', 'h', 'k', 'n', 'p', ':', 'S', ':', 'u', ':', 'U',
97	'4', '6',
98#ifdef	AUTHENTICATION
99	'a', ':', 'X', ':',
100#endif
101#ifdef BFTPDAEMON
102	'B',
103#endif
104#ifdef DIAGNOSTICS
105	'D', ':',
106#endif
107#ifdef	ENCRYPTION
108	'e', ':',
109#endif
110#ifdef	LINEMODE
111	'l',
112#endif
113	'\0'
114};
115
116int family = AF_INET;
117
118#ifndef	MAXHOSTNAMELEN
119#define	MAXHOSTNAMELEN 256
120#endif	/* MAXHOSTNAMELEN */
121
122char *hostname;
123char host_name[MAXHOSTNAMELEN];
124
125extern void telnet(int, int, char *);
126
127int level;
128char user_name[256];
129
130int
131main(int argc, char *argv[])
132{
133	u_long ultmp;
134	struct sockaddr_storage from;
135	int on = 1, fromlen;
136	int ch;
137#if	defined(IPPROTO_IP) && defined(IP_TOS)
138	int tos = -1;
139#endif
140	char *ep;
141
142	pfrontp = pbackp = ptyobuf;
143	netip = netibuf;
144	nfrontp = nbackp = netobuf;
145#ifdef	ENCRYPTION
146	nclearto = 0;
147#endif	/* ENCRYPTION */
148
149	/*
150	 * This initialization causes linemode to default to a configuration
151	 * that works on all telnet clients, including the FreeBSD client.
152	 * This is not quite the same as the telnet client issuing a "mode
153	 * character" command, but has most of the same benefits, and is
154	 * preferable since some clients (like usofts) don't have the
155	 * mode character command anyway and linemode breaks things.
156	 * The most notable symptom of fix is that csh "set filec" operations
157	 * like <ESC> (filename completion) and ^D (choices) keys now work
158	 * in telnet sessions and can be used more than once on the same line.
159	 * CR/LF handling is also corrected in some termio modes.  This
160	 * change resolves problem reports bin/771 and bin/1037.
161	 */
162
163	linemode=1;	/*Default to mode that works on bulk of clients*/
164
165	while ((ch = getopt(argc, argv, valid_opts)) != -1) {
166		switch(ch) {
167
168#ifdef	AUTHENTICATION
169		case 'a':
170			/*
171			 * Check for required authentication level
172			 */
173			if (strcmp(optarg, "debug") == 0) {
174				extern int auth_debug_mode;
175				auth_debug_mode = 1;
176			} else if (strcasecmp(optarg, "none") == 0) {
177				auth_level = 0;
178			} else if (strcasecmp(optarg, "other") == 0) {
179				auth_level = AUTH_OTHER;
180			} else if (strcasecmp(optarg, "user") == 0) {
181				auth_level = AUTH_USER;
182			} else if (strcasecmp(optarg, "valid") == 0) {
183				auth_level = AUTH_VALID;
184			} else if (strcasecmp(optarg, "off") == 0) {
185				/*
186				 * This hack turns off authentication
187				 */
188				auth_level = -1;
189			} else {
190				warnx("unknown authorization level for -a");
191			}
192			break;
193#endif	/* AUTHENTICATION */
194
195#ifdef BFTPDAEMON
196		case 'B':
197			bftpd++;
198			break;
199#endif /* BFTPDAEMON */
200
201		case 'd':
202			if (strcmp(optarg, "ebug") == 0) {
203				debug++;
204				break;
205			}
206			usage();
207			/* NOTREACHED */
208			break;
209
210#ifdef DIAGNOSTICS
211		case 'D':
212			/*
213			 * Check for desired diagnostics capabilities.
214			 */
215			if (!strcmp(optarg, "report")) {
216				diagnostic |= TD_REPORT|TD_OPTIONS;
217			} else if (!strcmp(optarg, "exercise")) {
218				diagnostic |= TD_EXERCISE;
219			} else if (!strcmp(optarg, "netdata")) {
220				diagnostic |= TD_NETDATA;
221			} else if (!strcmp(optarg, "ptydata")) {
222				diagnostic |= TD_PTYDATA;
223			} else if (!strcmp(optarg, "options")) {
224				diagnostic |= TD_OPTIONS;
225			} else {
226				usage();
227				/* NOT REACHED */
228			}
229			break;
230#endif /* DIAGNOSTICS */
231
232#ifdef	ENCRYPTION
233		case 'e':
234			if (strcmp(optarg, "debug") == 0) {
235				extern int encrypt_debug_mode;
236				encrypt_debug_mode = 1;
237				break;
238			}
239			usage();
240			/* NOTREACHED */
241			break;
242#endif	/* ENCRYPTION */
243
244		case 'h':
245			hostinfo = 0;
246			break;
247
248#ifdef	LINEMODE
249		case 'l':
250			alwayslinemode = 1;
251			break;
252#endif	/* LINEMODE */
253
254		case 'k':
255#if	defined(LINEMODE) && defined(KLUDGELINEMODE)
256			lmodetype = NO_AUTOKLUDGE;
257#else
258			/* ignore -k option if built without kludge linemode */
259#endif	/* defined(LINEMODE) && defined(KLUDGELINEMODE) */
260			break;
261
262		case 'n':
263			keepalive = 0;
264			break;
265
266		case 'p':
267			altlogin = optarg;
268			break;
269
270		case 'S':
271#ifdef	HAS_GETTOS
272			if ((tos = parsetos(optarg, "tcp")) < 0)
273				warnx("%s%s%s",
274					"bad TOS argument '", optarg,
275					"'; will try to use default TOS");
276#else
277#define	MAXTOS	255
278			ultmp = strtoul(optarg, &ep, 0);
279			if (*ep || ep == optarg || ultmp > MAXTOS)
280				warnx("%s%s%s",
281					"bad TOS argument '", optarg,
282					"'; will try to use default TOS");
283			else
284				tos = ultmp;
285#endif
286			break;
287
288		case 'u':
289			utmp_len = (size_t)atoi(optarg);
290			if (utmp_len >= sizeof(remote_hostname))
291				utmp_len = sizeof(remote_hostname) - 1;
292			break;
293
294		case 'U':
295			registerd_host_only = 1;
296			break;
297
298#ifdef	AUTHENTICATION
299		case 'X':
300			/*
301			 * Check for invalid authentication types
302			 */
303			auth_disable_name(optarg);
304			break;
305#endif	/* AUTHENTICATION */
306
307		case '4':
308			family = AF_INET;
309			break;
310
311#ifdef INET6
312		case '6':
313			family = AF_INET6;
314			break;
315#endif
316
317		default:
318			warnx("%c: unknown option", ch);
319			/* FALLTHROUGH */
320		case '?':
321			usage();
322			/* NOTREACHED */
323		}
324	}
325
326	argc -= optind;
327	argv += optind;
328
329	if (debug) {
330	    int s, ns, foo, error;
331	    const char *service = "telnet";
332	    struct addrinfo hints, *res;
333
334	    if (argc > 1) {
335		usage();
336		/* NOT REACHED */
337	    } else if (argc == 1)
338		service = *argv;
339
340	    memset(&hints, 0, sizeof(hints));
341	    hints.ai_flags = AI_PASSIVE;
342	    hints.ai_family = family;
343	    hints.ai_socktype = SOCK_STREAM;
344	    hints.ai_protocol = 0;
345	    error = getaddrinfo(NULL, service, &hints, &res);
346
347	    if (error) {
348		errx(1, "tcp/%s: %s\n", service, gai_strerror(error));
349		if (error == EAI_SYSTEM)
350		    errx(1, "tcp/%s: %s\n", service, strerror(errno));
351		usage();
352	    }
353
354	    s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
355	    if (s < 0)
356		    err(1, "socket");
357	    (void) setsockopt(s, SOL_SOCKET, SO_REUSEADDR,
358				(char *)&on, sizeof(on));
359	    if (debug > 1)
360	        (void) setsockopt(s, SOL_SOCKET, SO_DEBUG,
361				(char *)&on, sizeof(on));
362	    if (bind(s, res->ai_addr, res->ai_addrlen) < 0)
363		err(1, "bind");
364	    if (listen(s, 1) < 0)
365		err(1, "listen");
366	    foo = res->ai_addrlen;
367	    ns = accept(s, res->ai_addr, &foo);
368	    if (ns < 0)
369		err(1, "accept");
370	    (void) setsockopt(ns, SOL_SOCKET, SO_DEBUG,
371				(char *)&on, sizeof(on));
372	    (void) dup2(ns, 0);
373	    (void) close(ns);
374	    (void) close(s);
375#ifdef convex
376	} else if (argc == 1) {
377		; /* VOID*/		/* Just ignore the host/port name */
378#endif
379	} else if (argc > 0) {
380		usage();
381		/* NOT REACHED */
382	}
383
384	openlog("telnetd", LOG_PID | LOG_ODELAY, LOG_DAEMON);
385	fromlen = sizeof (from);
386	if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
387		warn("getpeername");
388		_exit(1);
389	}
390	if (keepalive &&
391	    setsockopt(0, SOL_SOCKET, SO_KEEPALIVE,
392			(char *)&on, sizeof (on)) < 0) {
393		syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
394	}
395
396#if	defined(IPPROTO_IP) && defined(IP_TOS)
397	if (from.ss_family == AF_INET) {
398# if	defined(HAS_GETTOS)
399		struct tosent *tp;
400		if (tos < 0 && (tp = gettosbyname("telnet", "tcp")))
401			tos = tp->t_tos;
402# endif
403		if (tos < 0)
404			tos = 020;	/* Low Delay bit */
405		if (tos
406		   && (setsockopt(0, IPPROTO_IP, IP_TOS,
407				  (char *)&tos, sizeof(tos)) < 0)
408		   && (errno != ENOPROTOOPT) )
409			syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
410	}
411#endif	/* defined(IPPROTO_IP) && defined(IP_TOS) */
412	net = 0;
413	doit((struct sockaddr *)&from);
414	/* NOTREACHED */
415	return(0);
416}  /* end of main */
417
418	void
419usage()
420{
421	fprintf(stderr, "usage: telnetd");
422#ifdef	AUTHENTICATION
423	fprintf(stderr,
424	    " [-4] [-6] [-a (debug|other|user|valid|off|none)]\n\t");
425#endif
426#ifdef BFTPDAEMON
427	fprintf(stderr, " [-B]");
428#endif
429	fprintf(stderr, " [-debug]");
430#ifdef DIAGNOSTICS
431	fprintf(stderr, " [-D (options|report|exercise|netdata|ptydata)]\n\t");
432#endif
433#ifdef	AUTHENTICATION
434	fprintf(stderr, " [-edebug]");
435#endif
436	fprintf(stderr, " [-h]");
437#if	defined(LINEMODE) && defined(KLUDGELINEMODE)
438	fprintf(stderr, " [-k]");
439#endif
440#ifdef LINEMODE
441	fprintf(stderr, " [-l]");
442#endif
443	fprintf(stderr, " [-n]");
444	fprintf(stderr, "\n\t");
445#ifdef	HAS_GETTOS
446	fprintf(stderr, " [-S tos]");
447#endif
448#ifdef	AUTHENTICATION
449	fprintf(stderr, " [-X auth-type]");
450#endif
451	fprintf(stderr, " [-u utmp_hostname_length] [-U]");
452	fprintf(stderr, " [port]\n");
453	exit(1);
454}
455
456/*
457 * getterminaltype
458 *
459 *	Ask the other end to send along its terminal type and speed.
460 * Output is the variable terminaltype filled in.
461 */
462static unsigned char ttytype_sbbuf[] = {
463	IAC, SB, TELOPT_TTYPE, TELQUAL_SEND, IAC, SE
464};
465
466
467#ifndef	AUTHENTICATION
468#define undef2 __unused
469#else
470#define undef2
471#endif
472
473static int
474getterminaltype(char *name undef2)
475{
476    int retval = -1;
477
478    settimer(baseline);
479#ifdef	AUTHENTICATION
480    /*
481     * Handle the Authentication option before we do anything else.
482     */
483    if (auth_level >= 0) {
484	send_do(TELOPT_AUTHENTICATION, 1);
485	while (his_will_wont_is_changing(TELOPT_AUTHENTICATION))
486	    ttloop();
487	if (his_state_is_will(TELOPT_AUTHENTICATION)) {
488	    retval = auth_wait(name);
489	}
490    }
491#endif
492
493#ifdef	ENCRYPTION
494    send_will(TELOPT_ENCRYPT, 1);
495#endif	/* ENCRYPTION */
496    send_do(TELOPT_TTYPE, 1);
497    send_do(TELOPT_TSPEED, 1);
498    send_do(TELOPT_XDISPLOC, 1);
499    send_do(TELOPT_NEW_ENVIRON, 1);
500    send_do(TELOPT_OLD_ENVIRON, 1);
501    while (
502#ifdef	ENCRYPTION
503	   his_do_dont_is_changing(TELOPT_ENCRYPT) ||
504#endif	/* ENCRYPTION */
505	   his_will_wont_is_changing(TELOPT_TTYPE) ||
506	   his_will_wont_is_changing(TELOPT_TSPEED) ||
507	   his_will_wont_is_changing(TELOPT_XDISPLOC) ||
508	   his_will_wont_is_changing(TELOPT_NEW_ENVIRON) ||
509	   his_will_wont_is_changing(TELOPT_OLD_ENVIRON)) {
510	ttloop();
511    }
512#ifdef	ENCRYPTION
513    /*
514     * Wait for the negotiation of what type of encryption we can
515     * send with.  If autoencrypt is not set, this will just return.
516     */
517    if (his_state_is_will(TELOPT_ENCRYPT)) {
518	encrypt_wait();
519    }
520#endif	/* ENCRYPTION */
521    if (his_state_is_will(TELOPT_TSPEED)) {
522	static unsigned char sb[] =
523			{ IAC, SB, TELOPT_TSPEED, TELQUAL_SEND, IAC, SE };
524
525	output_datalen(sb, sizeof sb);
526	DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
527    }
528    if (his_state_is_will(TELOPT_XDISPLOC)) {
529	static unsigned char sb[] =
530			{ IAC, SB, TELOPT_XDISPLOC, TELQUAL_SEND, IAC, SE };
531
532	output_datalen(sb, sizeof sb);
533	DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
534    }
535    if (his_state_is_will(TELOPT_NEW_ENVIRON)) {
536	static unsigned char sb[] =
537			{ IAC, SB, TELOPT_NEW_ENVIRON, TELQUAL_SEND, IAC, SE };
538
539	output_datalen(sb, sizeof sb);
540	DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
541    }
542    else if (his_state_is_will(TELOPT_OLD_ENVIRON)) {
543	static unsigned char sb[] =
544			{ IAC, SB, TELOPT_OLD_ENVIRON, TELQUAL_SEND, IAC, SE };
545
546	output_datalen(sb, sizeof sb);
547	DIAG(TD_OPTIONS, printsub('>', sb + 2, sizeof sb - 2););
548    }
549    if (his_state_is_will(TELOPT_TTYPE)) {
550
551	output_datalen(ttytype_sbbuf, sizeof ttytype_sbbuf);
552	DIAG(TD_OPTIONS, printsub('>', ttytype_sbbuf + 2,
553					sizeof ttytype_sbbuf - 2););
554    }
555    if (his_state_is_will(TELOPT_TSPEED)) {
556	while (sequenceIs(tspeedsubopt, baseline))
557	    ttloop();
558    }
559    if (his_state_is_will(TELOPT_XDISPLOC)) {
560	while (sequenceIs(xdisplocsubopt, baseline))
561	    ttloop();
562    }
563    if (his_state_is_will(TELOPT_NEW_ENVIRON)) {
564	while (sequenceIs(environsubopt, baseline))
565	    ttloop();
566    }
567    if (his_state_is_will(TELOPT_OLD_ENVIRON)) {
568	while (sequenceIs(oenvironsubopt, baseline))
569	    ttloop();
570    }
571    if (his_state_is_will(TELOPT_TTYPE)) {
572	char first[256], last[256];
573
574	while (sequenceIs(ttypesubopt, baseline))
575	    ttloop();
576
577	/*
578	 * If the other side has already disabled the option, then
579	 * we have to just go with what we (might) have already gotten.
580	 */
581	if (his_state_is_will(TELOPT_TTYPE) && !terminaltypeok(terminaltype)) {
582	    (void) strncpy(first, terminaltype, sizeof(first)-1);
583	    first[sizeof(first)-1] = '\0';
584	    for(;;) {
585		/*
586		 * Save the unknown name, and request the next name.
587		 */
588		(void) strncpy(last, terminaltype, sizeof(last)-1);
589		last[sizeof(last)-1] = '\0';
590		_gettermname();
591		if (terminaltypeok(terminaltype))
592		    break;
593		if ((strncmp(last, terminaltype, sizeof(last)) == 0) ||
594		    his_state_is_wont(TELOPT_TTYPE)) {
595		    /*
596		     * We've hit the end.  If this is the same as
597		     * the first name, just go with it.
598		     */
599		    if (strncmp(first, terminaltype, sizeof(first)) == 0)
600			break;
601		    /*
602		     * Get the terminal name one more time, so that
603		     * RFC1091 compliant telnets will cycle back to
604		     * the start of the list.
605		     */
606		     _gettermname();
607		    if (strncmp(first, terminaltype, sizeof(first)) != 0) {
608			(void) strncpy(terminaltype, first, sizeof(terminaltype)-1);
609			terminaltype[sizeof(terminaltype)-1] = '\0';
610		    }
611		    break;
612		}
613	    }
614	}
615    }
616    return(retval);
617}  /* end of getterminaltype */
618
619static void
620_gettermname(void)
621{
622    /*
623     * If the client turned off the option,
624     * we can't send another request, so we
625     * just return.
626     */
627    if (his_state_is_wont(TELOPT_TTYPE))
628	return;
629    settimer(baseline);
630    output_datalen(ttytype_sbbuf, sizeof ttytype_sbbuf);
631    DIAG(TD_OPTIONS, printsub('>', ttytype_sbbuf + 2,
632					sizeof ttytype_sbbuf - 2););
633    while (sequenceIs(ttypesubopt, baseline))
634	ttloop();
635}
636
637int
638terminaltypeok(char *s)
639{
640    char buf[1024];
641
642    if (terminaltype == NULL)
643	return(1);
644
645    /*
646     * tgetent() will return 1 if the type is known, and
647     * 0 if it is not known.  If it returns -1, it couldn't
648     * open the database.  But if we can't open the database,
649     * it won't help to say we failed, because we won't be
650     * able to verify anything else.  So, we treat -1 like 1.
651     */
652    if (tgetent(buf, s) == 0)
653	return(0);
654    return(1);
655}
656
657/*
658 * Get a pty, scan input lines.
659 */
660void
661doit(struct sockaddr *who)
662{
663	int err_; /* XXX */
664	int ptynum;
665
666	/*
667	 * Find an available pty to use.
668	 */
669#ifndef	convex
670	pty = getpty(&ptynum);
671	if (pty < 0)
672		fatal(net, "All network ports in use");
673#else
674	for (;;) {
675		char *lp;
676
677		if ((lp = getpty()) == NULL)
678			fatal(net, "Out of ptys");
679
680		if ((pty = open(lp, 2)) >= 0) {
681			strlcpy(line,lp,sizeof(line));
682			line[5] = 't';
683			break;
684		}
685	}
686#endif
687
688	/* get name of connected client */
689	if (realhostname_sa(remote_hostname, sizeof(remote_hostname) - 1,
690	    who, who->sa_len) == HOSTNAME_INVALIDADDR && registerd_host_only)
691		fatal(net, "Couldn't resolve your address into a host name.\r\n\
692	Please contact your net administrator");
693	remote_hostname[sizeof(remote_hostname) - 1] = '\0';
694
695	trimdomain(remote_hostname, UT_HOSTSIZE);
696	if (!isdigit(remote_hostname[0]) && strlen(remote_hostname) > utmp_len)
697		err_ = getnameinfo(who, who->sa_len, remote_hostname,
698				  sizeof(remote_hostname), NULL, 0,
699				  NI_NUMERICHOST);
700		/* XXX: do 'err_' check */
701
702	(void) gethostname(host_name, sizeof(host_name) - 1);
703	host_name[sizeof(host_name) - 1] = '\0';
704	hostname = host_name;
705
706#ifdef	AUTHENTICATION
707#ifdef	ENCRYPTION
708/* The above #ifdefs should actually be "or"'ed, not "and"'ed.
709 * This is a byproduct of needing "#ifdef" and not "#if defined()"
710 * for unifdef. XXX MarkM
711 */
712	auth_encrypt_init(hostname, remote_hostname, "TELNETD", 1);
713#endif
714#endif
715
716	init_env();
717	/*
718	 * get terminal type.
719	 */
720	*user_name = 0;
721	level = getterminaltype(user_name);
722	setenv("TERM", terminaltype ? terminaltype : "network", 1);
723
724	telnet(net, pty, remote_hostname);	/* begin server process */
725
726	/*NOTREACHED*/
727}  /* end of doit */
728
729/*
730 * Main loop.  Select from pty and network, and
731 * hand data to telnet receiver finite state machine.
732 */
733void
734telnet(int f, int p, char *host)
735{
736	int on = 1;
737#define	TABBUFSIZ	512
738	char	defent[TABBUFSIZ];
739	char	defstrs[TABBUFSIZ];
740#undef	TABBUFSIZ
741	char *HE;
742	char *HN;
743	char *IM;
744	int nfd;
745
746	/*
747	 * Initialize the slc mapping table.
748	 */
749	get_slc_defaults();
750
751	/*
752	 * Do some tests where it is desireable to wait for a response.
753	 * Rather than doing them slowly, one at a time, do them all
754	 * at once.
755	 */
756	if (my_state_is_wont(TELOPT_SGA))
757		send_will(TELOPT_SGA, 1);
758	/*
759	 * Is the client side a 4.2 (NOT 4.3) system?  We need to know this
760	 * because 4.2 clients are unable to deal with TCP urgent data.
761	 *
762	 * To find out, we send out a "DO ECHO".  If the remote system
763	 * answers "WILL ECHO" it is probably a 4.2 client, and we note
764	 * that fact ("WILL ECHO" ==> that the client will echo what
765	 * WE, the server, sends it; it does NOT mean that the client will
766	 * echo the terminal input).
767	 */
768	send_do(TELOPT_ECHO, 1);
769
770#ifdef	LINEMODE
771	if (his_state_is_wont(TELOPT_LINEMODE)) {
772		/* Query the peer for linemode support by trying to negotiate
773		 * the linemode option.
774		 */
775		linemode = 0;
776		editmode = 0;
777		send_do(TELOPT_LINEMODE, 1);  /* send do linemode */
778	}
779#endif	/* LINEMODE */
780
781	/*
782	 * Send along a couple of other options that we wish to negotiate.
783	 */
784	send_do(TELOPT_NAWS, 1);
785	send_will(TELOPT_STATUS, 1);
786	flowmode = 1;		/* default flow control state */
787	restartany = -1;	/* uninitialized... */
788	send_do(TELOPT_LFLOW, 1);
789
790	/*
791	 * Spin, waiting for a response from the DO ECHO.  However,
792	 * some REALLY DUMB telnets out there might not respond
793	 * to the DO ECHO.  So, we spin looking for NAWS, (most dumb
794	 * telnets so far seem to respond with WONT for a DO that
795	 * they don't understand...) because by the time we get the
796	 * response, it will already have processed the DO ECHO.
797	 * Kludge upon kludge.
798	 */
799	while (his_will_wont_is_changing(TELOPT_NAWS))
800		ttloop();
801
802	/*
803	 * But...
804	 * The client might have sent a WILL NAWS as part of its
805	 * startup code; if so, we'll be here before we get the
806	 * response to the DO ECHO.  We'll make the assumption
807	 * that any implementation that understands about NAWS
808	 * is a modern enough implementation that it will respond
809	 * to our DO ECHO request; hence we'll do another spin
810	 * waiting for the ECHO option to settle down, which is
811	 * what we wanted to do in the first place...
812	 */
813	if (his_want_state_is_will(TELOPT_ECHO) &&
814	    his_state_is_will(TELOPT_NAWS)) {
815		while (his_will_wont_is_changing(TELOPT_ECHO))
816			ttloop();
817	}
818	/*
819	 * On the off chance that the telnet client is broken and does not
820	 * respond to the DO ECHO we sent, (after all, we did send the
821	 * DO NAWS negotiation after the DO ECHO, and we won't get here
822	 * until a response to the DO NAWS comes back) simulate the
823	 * receipt of a will echo.  This will also send a WONT ECHO
824	 * to the client, since we assume that the client failed to
825	 * respond because it believes that it is already in DO ECHO
826	 * mode, which we do not want.
827	 */
828	if (his_want_state_is_will(TELOPT_ECHO)) {
829		DIAG(TD_OPTIONS, output_data("td: simulating recv\r\n"));
830		willoption(TELOPT_ECHO);
831	}
832
833	/*
834	 * Finally, to clean things up, we turn on our echo.  This
835	 * will break stupid 4.2 telnets out of local terminal echo.
836	 */
837
838	if (my_state_is_wont(TELOPT_ECHO))
839		send_will(TELOPT_ECHO, 1);
840
841	/*
842	 * Turn on packet mode
843	 */
844	(void) ioctl(p, TIOCPKT, (char *)&on);
845
846#if	defined(LINEMODE) && defined(KLUDGELINEMODE)
847	/*
848	 * Continuing line mode support.  If client does not support
849	 * real linemode, attempt to negotiate kludge linemode by sending
850	 * the do timing mark sequence.
851	 */
852	if (lmodetype < REAL_LINEMODE)
853		send_do(TELOPT_TM, 1);
854#endif	/* defined(LINEMODE) && defined(KLUDGELINEMODE) */
855
856	/*
857	 * Call telrcv() once to pick up anything received during
858	 * terminal type negotiation, 4.2/4.3 determination, and
859	 * linemode negotiation.
860	 */
861	telrcv();
862
863	(void) ioctl(f, FIONBIO, (char *)&on);
864	(void) ioctl(p, FIONBIO, (char *)&on);
865
866#if	defined(SO_OOBINLINE)
867	(void) setsockopt(net, SOL_SOCKET, SO_OOBINLINE,
868				(char *)&on, sizeof on);
869#endif	/* defined(SO_OOBINLINE) */
870
871#ifdef	SIGTSTP
872	(void) signal(SIGTSTP, SIG_IGN);
873#endif
874#ifdef	SIGTTOU
875	/*
876	 * Ignoring SIGTTOU keeps the kernel from blocking us
877	 * in ttioct() in /sys/tty.c.
878	 */
879	(void) signal(SIGTTOU, SIG_IGN);
880#endif
881
882	(void) signal(SIGCHLD, cleanup);
883
884#ifdef  TIOCNOTTY
885	{
886		int t;
887		t = open(_PATH_TTY, O_RDWR);
888		if (t >= 0) {
889			(void) ioctl(t, TIOCNOTTY, (char *)0);
890			(void) close(t);
891		}
892	}
893#endif
894
895	/*
896	 * Show banner that getty never gave.
897	 *
898	 * We put the banner in the pty input buffer.  This way, it
899	 * gets carriage return null processing, etc., just like all
900	 * other pty --> client data.
901	 */
902
903	if (getent(defent, "default") == 1) {
904		char *cp=defstrs;
905
906		HE = Getstr("he", &cp);
907		HN = Getstr("hn", &cp);
908		IM = Getstr("im", &cp);
909		if (HN && *HN)
910			(void) strlcpy(host_name, HN, sizeof(host_name));
911		if (IM == 0)
912			IM = strdup("");
913	} else {
914		IM = strdup(DEFAULT_IM);
915		HE = 0;
916	}
917	edithost(HE, host_name);
918	if (hostinfo && *IM)
919		putf(IM, ptyibuf2);
920
921	if (pcc)
922		(void) strncat(ptyibuf2, ptyip, pcc+1);
923	ptyip = ptyibuf2;
924	pcc = strlen(ptyip);
925#ifdef	LINEMODE
926	/*
927	 * Last check to make sure all our states are correct.
928	 */
929	init_termbuf();
930	localstat();
931#endif	/* LINEMODE */
932
933	DIAG(TD_REPORT, output_data("td: Entering processing loop\r\n"));
934
935	/*
936	 * Startup the login process on the slave side of the terminal
937	 * now.  We delay this until here to insure option negotiation
938	 * is complete.
939	 */
940	startslave(host, level, user_name);
941
942	nfd = ((f > p) ? f : p) + 1;
943	for (;;) {
944		fd_set ibits, obits, xbits;
945		int c;
946
947		if (ncc < 0 && pcc < 0)
948			break;
949
950		FD_ZERO(&ibits);
951		FD_ZERO(&obits);
952		FD_ZERO(&xbits);
953		/*
954		 * Never look for input if there's still
955		 * stuff in the corresponding output buffer
956		 */
957		if (nfrontp - nbackp || pcc > 0) {
958			FD_SET(f, &obits);
959		} else {
960			FD_SET(p, &ibits);
961		}
962		if (pfrontp - pbackp || ncc > 0) {
963			FD_SET(p, &obits);
964		} else {
965			FD_SET(f, &ibits);
966		}
967		if (!SYNCHing) {
968			FD_SET(f, &xbits);
969		}
970		if ((c = select(nfd, &ibits, &obits, &xbits,
971						(struct timeval *)0)) < 1) {
972			if (c == -1) {
973				if (errno == EINTR) {
974					continue;
975				}
976			}
977			sleep(5);
978			continue;
979		}
980
981		/*
982		 * Any urgent data?
983		 */
984		if (FD_ISSET(net, &xbits)) {
985		    SYNCHing = 1;
986		}
987
988		/*
989		 * Something to read from the network...
990		 */
991		if (FD_ISSET(net, &ibits)) {
992#if	!defined(SO_OOBINLINE)
993			/*
994			 * In 4.2 (and 4.3 beta) systems, the
995			 * OOB indication and data handling in the kernel
996			 * is such that if two separate TCP Urgent requests
997			 * come in, one byte of TCP data will be overlaid.
998			 * This is fatal for Telnet, but we try to live
999			 * with it.
1000			 *
1001			 * In addition, in 4.2 (and...), a special protocol
1002			 * is needed to pick up the TCP Urgent data in
1003			 * the correct sequence.
1004			 *
1005			 * What we do is:  if we think we are in urgent
1006			 * mode, we look to see if we are "at the mark".
1007			 * If we are, we do an OOB receive.  If we run
1008			 * this twice, we will do the OOB receive twice,
1009			 * but the second will fail, since the second
1010			 * time we were "at the mark", but there wasn't
1011			 * any data there (the kernel doesn't reset
1012			 * "at the mark" until we do a normal read).
1013			 * Once we've read the OOB data, we go ahead
1014			 * and do normal reads.
1015			 *
1016			 * There is also another problem, which is that
1017			 * since the OOB byte we read doesn't put us
1018			 * out of OOB state, and since that byte is most
1019			 * likely the TELNET DM (data mark), we would
1020			 * stay in the TELNET SYNCH (SYNCHing) state.
1021			 * So, clocks to the rescue.  If we've "just"
1022			 * received a DM, then we test for the
1023			 * presence of OOB data when the receive OOB
1024			 * fails (and AFTER we did the normal mode read
1025			 * to clear "at the mark").
1026			 */
1027		    if (SYNCHing) {
1028			int atmark;
1029
1030			(void) ioctl(net, SIOCATMARK, (char *)&atmark);
1031			if (atmark) {
1032			    ncc = recv(net, netibuf, sizeof (netibuf), MSG_OOB);
1033			    if ((ncc == -1) && (errno == EINVAL)) {
1034				ncc = read(net, netibuf, sizeof (netibuf));
1035				if (sequenceIs(didnetreceive, gotDM)) {
1036				    SYNCHing = stilloob(net);
1037				}
1038			    }
1039			} else {
1040			    ncc = read(net, netibuf, sizeof (netibuf));
1041			}
1042		    } else {
1043			ncc = read(net, netibuf, sizeof (netibuf));
1044		    }
1045		    settimer(didnetreceive);
1046#else	/* !defined(SO_OOBINLINE)) */
1047		    ncc = read(net, netibuf, sizeof (netibuf));
1048#endif	/* !defined(SO_OOBINLINE)) */
1049		    if (ncc < 0 && errno == EWOULDBLOCK)
1050			ncc = 0;
1051		    else {
1052			if (ncc <= 0) {
1053			    break;
1054			}
1055			netip = netibuf;
1056		    }
1057		    DIAG((TD_REPORT | TD_NETDATA),
1058			output_data("td: netread %d chars\r\n", ncc));
1059		    DIAG(TD_NETDATA, printdata("nd", netip, ncc));
1060		}
1061
1062		/*
1063		 * Something to read from the pty...
1064		 */
1065		if (FD_ISSET(p, &ibits)) {
1066			pcc = read(p, ptyibuf, BUFSIZ);
1067			/*
1068			 * On some systems, if we try to read something
1069			 * off the master side before the slave side is
1070			 * opened, we get EIO.
1071			 */
1072			if (pcc < 0 && (errno == EWOULDBLOCK ||
1073#ifdef	EAGAIN
1074					errno == EAGAIN ||
1075#endif
1076					errno == EIO)) {
1077				pcc = 0;
1078			} else {
1079				if (pcc <= 0)
1080					break;
1081#ifdef	LINEMODE
1082				/*
1083				 * If ioctl from pty, pass it through net
1084				 */
1085				if (ptyibuf[0] & TIOCPKT_IOCTL) {
1086					copy_termbuf(ptyibuf+1, pcc-1);
1087					localstat();
1088					pcc = 1;
1089				}
1090#endif	/* LINEMODE */
1091				if (ptyibuf[0] & TIOCPKT_FLUSHWRITE) {
1092					netclear();	/* clear buffer back */
1093#ifndef	NO_URGENT
1094					/*
1095					 * There are client telnets on some
1096					 * operating systems get screwed up
1097					 * royally if we send them urgent
1098					 * mode data.
1099					 */
1100					output_data("%c%c", IAC, DM);
1101					neturg = nfrontp-1; /* off by one XXX */
1102					DIAG(TD_OPTIONS,
1103					    printoption("td: send IAC", DM));
1104
1105#endif
1106				}
1107				if (his_state_is_will(TELOPT_LFLOW) &&
1108				    (ptyibuf[0] &
1109				     (TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))) {
1110					int newflow =
1111					    ptyibuf[0] & TIOCPKT_DOSTOP ? 1 : 0;
1112					if (newflow != flowmode) {
1113						flowmode = newflow;
1114						output_data("%c%c%c%c%c%c",
1115							IAC, SB, TELOPT_LFLOW,
1116							flowmode ? LFLOW_ON
1117								 : LFLOW_OFF,
1118							IAC, SE);
1119						DIAG(TD_OPTIONS, printsub('>',
1120						    (unsigned char *)nfrontp-4,
1121						    4););
1122					}
1123				}
1124				pcc--;
1125				ptyip = ptyibuf+1;
1126			}
1127		}
1128
1129		while (pcc > 0) {
1130			if ((&netobuf[BUFSIZ] - nfrontp) < 2)
1131				break;
1132			c = *ptyip++ & 0377, pcc--;
1133			if (c == IAC)
1134				output_data("%c", c);
1135			output_data("%c", c);
1136			if ((c == '\r') && (my_state_is_wont(TELOPT_BINARY))) {
1137				if (pcc > 0 && ((*ptyip & 0377) == '\n')) {
1138					output_data("%c", *ptyip++ & 0377);
1139					pcc--;
1140				} else
1141					output_data("%c", '\0');
1142			}
1143		}
1144
1145		if (FD_ISSET(f, &obits) && (nfrontp - nbackp) > 0)
1146			netflush();
1147		if (ncc > 0)
1148			telrcv();
1149		if (FD_ISSET(p, &obits) && (pfrontp - pbackp) > 0)
1150			ptyflush();
1151	}
1152	cleanup(0);
1153}  /* end of telnet */
1154
1155#ifndef	TCSIG
1156# ifdef	TIOCSIG
1157#  define TCSIG TIOCSIG
1158# endif
1159#endif
1160
1161/*
1162 * Send interrupt to process on other side of pty.
1163 * If it is in raw mode, just write NULL;
1164 * otherwise, write intr char.
1165 */
1166void
1167interrupt(void)
1168{
1169	ptyflush();	/* half-hearted */
1170
1171#ifdef	TCSIG
1172	(void) ioctl(pty, TCSIG, SIGINT);
1173#else	/* TCSIG */
1174	init_termbuf();
1175	*pfrontp++ = slctab[SLC_IP].sptr ?
1176			(unsigned char)*slctab[SLC_IP].sptr : '\177';
1177#endif	/* TCSIG */
1178}
1179
1180/*
1181 * Send quit to process on other side of pty.
1182 * If it is in raw mode, just write NULL;
1183 * otherwise, write quit char.
1184 */
1185void
1186sendbrk(void)
1187{
1188	ptyflush();	/* half-hearted */
1189#ifdef	TCSIG
1190	(void) ioctl(pty, TCSIG, SIGQUIT);
1191#else	/* TCSIG */
1192	init_termbuf();
1193	*pfrontp++ = slctab[SLC_ABORT].sptr ?
1194			(unsigned char)*slctab[SLC_ABORT].sptr : '\034';
1195#endif	/* TCSIG */
1196}
1197
1198void
1199sendsusp(void)
1200{
1201#ifdef	SIGTSTP
1202	ptyflush();	/* half-hearted */
1203# ifdef	TCSIG
1204	(void) ioctl(pty, TCSIG, SIGTSTP);
1205# else	/* TCSIG */
1206	*pfrontp++ = slctab[SLC_SUSP].sptr ?
1207			(unsigned char)*slctab[SLC_SUSP].sptr : '\032';
1208# endif	/* TCSIG */
1209#endif	/* SIGTSTP */
1210}
1211
1212/*
1213 * When we get an AYT, if ^T is enabled, use that.  Otherwise,
1214 * just send back "[Yes]".
1215 */
1216void
1217recv_ayt(void)
1218{
1219#if	defined(SIGINFO) && defined(TCSIG)
1220	if (slctab[SLC_AYT].sptr && *slctab[SLC_AYT].sptr != _POSIX_VDISABLE) {
1221		(void) ioctl(pty, TCSIG, SIGINFO);
1222		return;
1223	}
1224#endif
1225	output_data("\r\n[Yes]\r\n");
1226}
1227
1228void
1229doeof(void)
1230{
1231	init_termbuf();
1232
1233#if	defined(LINEMODE) && defined(USE_TERMIO) && (VEOF == VMIN)
1234	if (!tty_isediting()) {
1235		extern char oldeofc;
1236		*pfrontp++ = oldeofc;
1237		return;
1238	}
1239#endif
1240	*pfrontp++ = slctab[SLC_EOF].sptr ?
1241			(unsigned char)*slctab[SLC_EOF].sptr : '\004';
1242}
1243