telnetd.c

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· C语言 代码 · 共 1,646 行 · 第 1/3 页

#ifndef lint
static	char	*sccsid = "@(#)telnetd.c	4.1	(ULTRIX)	7/2/90";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1984,1988 by			*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/
/*
 * Copyright (c) 1983,1986 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */
/*
 * Modification History:
 *
 * 30-Aug-88    Michael G. Mc Menemy
 *      Fixed hang in cleanup by closing master side of pty before
 *      calling vhangup.
 *      Flush any remaining output from slave pty to the master pty for
 *      the telnet client.
 *
 * 09-Jun-88	Mark Parenti
 *	Changed signal handlers to void.
 *
 */
/*
#ifndef lint
char copyright[] =
" Copyright (c) 1983 Regents of the University of California.\n\
 All rights reserved.\n";
#endif not lint

#ifndef lint
static char sccsid[] = "telnetd.c	5.18 (Berkeley) 5/12/86";
#endif not lint
*/
/*
 * Telnet server.
 */
#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/time.h>

#include <netinet/in.h>

#include <arpa/telnet.h>

#include <stdio.h>
#include <signal.h>
#include <errno.h>
#include <sgtty.h>
#include <netdb.h>
#include <syslog.h>

#include <ctype.h>

#define	OPT_NO			0		/* won't do this option */
#define	OPT_YES			1		/* will do this option */
#define	OPT_YES_BUT_ALWAYS_LOOK	2
#define	OPT_NO_BUT_ALWAYS_LOOK	3
char	hisopts[256];
char	myopts[256];

char	doopt[] = { IAC, DO, '%', 'c', 0 };
char	dont[] = { IAC, DONT, '%', 'c', 0 };
char	will[] = { IAC, WILL, '%', 'c', 0 };
char	wont[] = { IAC, WONT, '%', 'c', 0 };

/*
 * I/O data buffers, pointers, and counters.
 */
char	ptyibuf[BUFSIZ], *ptyip = ptyibuf;

char	ptyobuf[BUFSIZ], *pfrontp = ptyobuf, *pbackp = ptyobuf;

char	netibuf[BUFSIZ], *netip = netibuf;
#define	NIACCUM(c)	{   *netip++ = c; \
			    ncc++; \
			}

char	netobuf[BUFSIZ], *nfrontp = netobuf, *nbackp = netobuf;
char	*neturg = 0;		/* one past last bye of urgent data */
	/* the remote system seems to NOT be an old 4.2 */
int	not42 = 1;

#ifdef 43BSD
char BANNER1[] = "\r\n\r\n 4.3 BSD (",
    BANNER2[] = ")\r\n\r\0\r\n\r\0";
#else
char *BANNER1;
#endif
#define	TABBUFSIZ	512

		/* buffer for sub-options */
char	subbuffer[100], *subpointer= subbuffer, *subend= subbuffer;
#define	SB_CLEAR()	subpointer = subbuffer;
#define	SB_TERM()	{ subend = subpointer; SB_CLEAR(); }
#define	SB_ACCUM(c)	if (subpointer < (subbuffer+sizeof subbuffer)) { \
				*subpointer++ = (c); \
			}
#define	SB_GET()	((*subpointer++)&0xff)
#define	SB_EOF()	(subpointer >= subend)

int	pcc, ncc;

int	pty, net;
int	inter;
extern	char **environ;
extern	int errno;
char	*line;
int	SYNCHing = 0;		/* we are in TELNET SYNCH mode */
/*
 * The following are some clocks used to decide how to interpret
 * the relationship between various variables.
 */

struct {
    int
	system,			/* what the current time is */
	echotoggle,		/* last time user entered echo character */
	modenegotiated,		/* last time operating mode negotiated */
	didnetreceive,		/* last time we read data from network */
	ttypeopt,		/* ttype will/won't received */
	ttypesubopt,		/* ttype subopt is received */
	getterminal,		/* time started to get terminal information */
	gotDM;			/* when did we last see a data mark */
} clocks;

#define	settimer(x)	(clocks.x = ++clocks.system)
#define	sequenceIs(x,y)	(clocks.x < clocks.y)

main(argc, argv)
	char *argv[];
{
	struct sockaddr_in from;
	int on = 1, fromlen;

#if	defined(DEBUG)
	{
	    int s, ns, foo;
	    struct servent *sp;
	    static struct sockaddr_in sin = { AF_INET };

	    sp = getservbyname("telnet", "tcp");
	    if (sp == 0) {
		    fprintf(stderr, "telnetd: tcp/telnet: unknown service\n");
		    exit(1);
	    }
	    sin.sin_port = sp->s_port;
	    argc--, argv++;
	    if (argc > 0) {
		    sin.sin_port = atoi(*argv);
		    sin.sin_port = htons((u_short)sin.sin_port);
	    }

	    s = socket(AF_INET, SOCK_STREAM, 0);
	    if (s < 0) {
		    perror("telnetd: socket");;
		    exit(1);
	    }
	    if (bind(s, &sin, sizeof sin) < 0) {
		perror("bind");
		exit(1);
	    }
	    if (listen(s, 1) < 0) {
		perror("listen");
		exit(1);
	    }
	    foo = sizeof sin;
	    ns = accept(s, &sin, &foo);
	    if (ns < 0) {
		perror("accept");
		exit(1);
	    }
	    dup2(ns, 0);
	    close(s);
	}
#endif	/* defined(DEBUG) */
#ifdef 43BSD
	openlog("telnetd", LOG_PID | LOG_ODELAY, LOG_DAEMON);
#else
	openlog("telnetd", LOG_PID );
#endif
	fromlen = sizeof (from);
	if (getpeername(0, &from, &fromlen) < 0) {
		fprintf(stderr, "%s: ", argv[0]);
		perror("getpeername");
		_exit(1);
	}
	if (setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0) {
		syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
	}
	doit(0, &from);
}

char	*terminaltype = 0;
char	*envinit[2];
void	cleanup();

/*
 * ttloop
 *
 *	A small subroutine to flush the network output buffer, get some data
 * from the network, and pass it through the telnet state machine.  We
 * also flush the pty input buffer (by dropping its data) if it becomes
 * too full.
 */

void
ttloop()
{
    if (nfrontp-nbackp) {
	netflush();
    }
    ncc = read(net, netibuf, sizeof netibuf);
    if (ncc < 0) {
	syslog(LOG_INFO, "ttloop:  read: %m\n");
	exit(1);
    } else if (ncc == 0) {
	syslog(LOG_INFO, "ttloop:  peer died: %m\n");
	exit(1);
    }
    netip = netibuf;
    telrcv();			/* state machine */
    if (ncc > 0) {
	pfrontp = pbackp = ptyobuf;
	telrcv();
    }
}

/*
 * getterminaltype
 *
 *	Ask the other end to send along its terminal type.
 * Output is the variable terminaltype filled in.
 */

void
getterminaltype()
{
    static char sbuf[] = { IAC, DO, TELOPT_TTYPE };

    settimer(getterminal);
    bcopy(sbuf, nfrontp, sizeof sbuf);
    nfrontp += sizeof sbuf;
    hisopts[TELOPT_TTYPE] = OPT_YES_BUT_ALWAYS_LOOK;
    while (sequenceIs(ttypeopt, getterminal)) {
	ttloop();
    }
    if (hisopts[TELOPT_TTYPE] == OPT_YES) {
	static char sbbuf[] = { IAC, SB, TELOPT_TTYPE, TELQUAL_SEND, IAC, SE };

	bcopy(sbbuf, nfrontp, sizeof sbbuf);
	nfrontp += sizeof sbbuf;
	while (sequenceIs(ttypesubopt, getterminal)) {
	    ttloop();
	}
    }
}

/*
 * Get a pty, scan input lines.
 */
doit(f, who)
	int f;
	struct sockaddr_in *who;
{
	char *host, *inet_ntoa();
	int i, p, t;
	struct sgttyb b;
	struct hostent *hp;
	int c;

	for (c = 'p'; c <= 'z'; c++) {
		struct stat stb;

		line = "/dev/ptyXX";
		line[strlen("/dev/pty")] = c;
		line[strlen("/dev/ptyp")] = '0';
		if (stat(line, &stb) < 0)
			break;
		for (i = 0; i < 16; i++) {
			line[strlen("/dev/ptyp")] = "0123456789abcdef"[i];
			p = open(line, 2);
			if (p > 0)
				goto gotpty;
		}
	}
	fatal(f, "All network ports in use");
	/*NOTREACHED*/
gotpty:
	dup2(f, 0);
	line[strlen("/dev/")] = 't';
	t = open("/dev/tty", O_RDWR);
	if (t >= 0) {
		ioctl(t, TIOCNOTTY, 0);
		close(t);
	}
	t = open(line, O_RDWR);
	if (t < 0)
		fatalperror(f, line, errno);
	ioctl(t, TIOCGETP, &b);
	b.sg_flags = CRMOD|XTABS|ANYP;
	ioctl(t, TIOCSETP, &b);
	ioctl(p, TIOCGETP, &b);
	b.sg_flags &= ~ECHO;
	ioctl(p, TIOCSETP, &b);
	hp = gethostbyaddr(&who->sin_addr, sizeof (struct in_addr),
		who->sin_family);
	if (hp)
		host = hp->h_name;
	else
		host = inet_ntoa(who->sin_addr);

	net = f;
	pty = p;

	/*
	 * get terminal type.
	 */
	getterminaltype();

	if ((i = fork()) < 0)
		fatalperror(f, "fork", errno);
	if (i)
		telnet(f, p);
	close(f);
	close(p);
	dup2(t, 0);
	dup2(t, 1);
	dup2(t, 2);
	close(t);
	envinit[0] = terminaltype;
	envinit[1] = 0;
	environ = envinit;
	/*
	 * -h : pass on name of host.
	 *		WARNING:  -h is accepted by login if and only if
	 *			getuid() == 0.
	 * -p : don't clobber the environment (so terminal type stays set).
	 */
	execl("/bin/login", "login", "-h", host,
					terminaltype ? "-p" : 0, 0);
	fatalperror(f, "/bin/login", errno);
	/*NOTREACHED*/
}

fatal(f, msg)
	int f;
	char *msg;
{
	char buf[BUFSIZ];

	(void) sprintf(buf, "telnetd: %s.\r\n", msg);
	(void) write(f, buf, strlen(buf));
	exit(1);
}

fatalperror(f, msg, errno)
	int f;
	char *msg;
	int errno;
{
	char buf[BUFSIZ];
	extern char *sys_errlist[];

	(void) sprintf(buf, "%s: %s\r\n", msg, sys_errlist[errno]);
	fatal(f, buf);
}


/*
 * Check a descriptor to see if out of band data exists on it.
 */


stilloob(s)
int	s;		/* socket number */
{
    static struct timeval timeout = { 0 };
    fd_set	excepts;
    int value;

    do {
	FD_ZERO(&excepts);
	FD_SET(s, &excepts);
	value = select(s+1, (fd_set *)0, (fd_set *)0, &excepts, &timeout);
    } while ((value == -1) && (errno == EINTR));

    if (value < 0) {
	fatalperror(pty, "select", errno);
    }
    if (FD_ISSET(s, &excepts)) {
	return 1;
    } else {
	return 0;
    }
}

/*
 * Main loop.  Select from pty and network, and
 * hand data to telnet receiver finite state machine.
 */
char hostname[MAXHOSTNAMELEN];
telnet(f, p)
{
	int on = 1;

	ioctl(f, FIONBIO, &on);
	ioctl(p, FIONBIO, &on);
#if	defined(SO_OOBINLINE)
	setsockopt(net, SOL_SOCKET, SO_OOBINLINE, &on, sizeof on);
#endif	/* defined(SO_OOBINLINE) */
	signal(SIGTSTP, SIG_IGN);
        /*
	 * Ignoring SIGTTOU keeps the kernel from blocking us
	 * in ttioctl() in /sys/tty.c.
	 */
	signal(SIGTTOU, SIG_IGN);
	signal(SIGCHLD, cleanup);
	setpgrp(0, 0);

	/*
	 * Request to do remote echo and to suppress go ahead.
	 */
	if (!myopts[TELOPT_ECHO]) {
	    dooption(TELOPT_ECHO);
	}
	if (!myopts[TELOPT_SGA]) {
	    dooption(TELOPT_SGA);
	}
	/*
	 * Is the client side a 4.2 (NOT 4.3) system?  We need to know this
	 * because 4.2 clients are unable to deal with TCP urgent data.
	 *
	 * To find out, we send out a "DO ECHO".  If the remote system
	 * answers "WILL ECHO" it is probably a 4.2 client, and we note
	 * that fact ("WILL ECHO" ==> that the client will echo what
	 * WE, the server, sends it; it does NOT mean that the client will
	 * echo the terminal input).
	 */
	(void) sprintf(nfrontp, doopt, TELOPT_ECHO);
	nfrontp += sizeof doopt-2;
	hisopts[TELOPT_ECHO] = OPT_YES_BUT_ALWAYS_LOOK;

	/*
	 * Show banner that getty never gave.
	 *
	 * The banner includes some null's (for TELNET CR disambiguation),
	 * so we have to be somewhat complicated.
	 */

	gethostname(hostname, sizeof (hostname));

#ifdef 43bsd
	bcopy(BANNER1, nfrontp, sizeof BANNER1 -1);
	nfrontp += sizeof BANNER1 - 1;
	bcopy(hostname, nfrontp, strlen(hostname));
	nfrontp += strlen(hostname);
	bcopy(BANNER2, nfrontp, sizeof BANNER2 -1);
	nfrontp += sizeof BANNER2 - 1;
#else
	{
		char buffer[TABBUFSIZ], barea[TABBUFSIZ];
		char *getstr(), *area = barea;
		if(getent(buffer, "default") >0) {
			BANNER1 = getstr("im", &area);
			bcopy(BANNER1, nfrontp, strlen(BANNER1));
			nfrontp += strlen(BANNER1);
		}
	}
#endif

	/*
	 * Call telrcv() once to pick up anything received during
	 * terminal type negotiation.
	 */
	telrcv();

	for (;;) {
		fd_set ibits, obits, xbits;
		register int c;

		if (ncc < 0 && pcc < 0)
			break;

		FD_ZERO(&ibits);
		FD_ZERO(&obits);
		FD_ZERO(&xbits);
		/*
		 * Never look for input if there's still
		 * stuff in the corresponding output buffer
		 */
		if (nfrontp - nbackp || pcc > 0) {
			FD_SET(f, &obits);
		} else {
			FD_SET(p, &ibits);
		}
		if (pfrontp - pbackp || ncc > 0) {
			FD_SET(p, &obits);
		} else {
			FD_SET(f, &ibits);
		}
		if (!SYNCHing) {
			FD_SET(f, &xbits);
		}
		if ((c = select(16, &ibits, &obits, &xbits,
						(struct timeval *)0)) < 1) {
			if (c == -1) {
				if (errno == EINTR) {
					continue;
				}
			}
			sleep(1);
			continue;
		}

		/*
		 * Any urgent data?
		 */
		if (FD_ISSET(net, &xbits)) {