xref: /csrg-svn/libexec/rlogind/rlogind.c (revision 35440)

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#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[] = "@(#)rlogind.c	5.16 (Berkeley) 08/31/88";
#endif not lint

/*
 * remote login server:
 *	remuser\0
 *	locuser\0
 *	terminal info\0
 *	data
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/file.h>

#include <netinet/in.h>

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

# ifndef TIOCPKT_WINDOW
# define TIOCPKT_WINDOW 0x80
# endif TIOCPKT_WINDOW

extern	int errno;
int	reapchild();
struct	passwd *getpwnam();
char	*malloc();

/*ARGSUSED*/
main(argc, argv)
	int argc;
	char **argv;
{
	int on = 1, fromlen;
	struct sockaddr_in from;

	openlog("rlogind", LOG_PID | LOG_AUTH, LOG_AUTH);
	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);
}

int	child;
int	cleanup();
int	netf;
char	*line;
extern	char	*inet_ntoa();

struct winsize win = { 0, 0, 0, 0 };


doit(f, fromp)
	int f;
	struct sockaddr_in *fromp;
{
	int i, p, t, pid, on = 1;
	register struct hostent *hp;
	struct hostent hostent;
	char c;

	alarm(60);
	read(f, &c, 1);
	if (c != 0)
		exit(1);
	alarm(0);
	fromp->sin_port = ntohs((u_short)fromp->sin_port);
	hp = gethostbyaddr(&fromp->sin_addr, sizeof (struct in_addr),
		fromp->sin_family);
	if (hp == 0) {
		/*
		 * Only the name is used below.
		 */
		hp = &hostent;
		hp->h_name = inet_ntoa(fromp->sin_addr);
	}
	if (fromp->sin_family != AF_INET ||
	    fromp->sin_port >= IPPORT_RESERVED ||
	    fromp->sin_port < IPPORT_RESERVED/2)
		fatal(f, "Permission denied");
	write(f, "", 1);
	for (c = 'p'; c <= 's'; 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[sizeof("/dev/ptyp") - 1] = "0123456789abcdef"[i];
			p = open(line, O_RDWR);
			if (p > 0)
				goto gotpty;
		}
	}
	fatal(f, "Out of ptys");
	/*NOTREACHED*/
gotpty:
	(void) ioctl(p, TIOCSWINSZ, &win);
	netf = f;
	line[strlen("/dev/")] = 't';
	t = open(line, O_RDWR);
	if (t < 0)
		fatalperror(f, line);
	if (fchmod(t, 0))
		fatalperror(f, line);
	(void)signal(SIGHUP, SIG_IGN);
	vhangup();
	(void)signal(SIGHUP, SIG_DFL);
	t = open(line, O_RDWR);
	if (t < 0)
		fatalperror(f, line);
	{
		struct sgttyb b;

		(void)ioctl(t, TIOCGETP, &b);
		b.sg_flags = RAW|ANYP;
		(void)ioctl(t, TIOCSETP, &b);
	}
#ifdef DEBUG
	{
		int tt = open("/dev/tty", O_RDWR);
		if (tt > 0) {
			(void)ioctl(tt, TIOCNOTTY, 0);
			(void)close(tt);
		}
	}
#endif
	pid = fork();
	if (pid < 0)
		fatalperror(f, "");
	if (pid == 0) {
		close(f), close(p);
		dup2(t, 0), dup2(t, 1), dup2(t, 2);
		close(t);
		execl("/bin/login", "login", "-r", hp->h_name, 0);
		fatalperror(2, "/bin/login");
		/*NOTREACHED*/
	}
	close(t);
	ioctl(f, FIONBIO, &on);
	ioctl(p, FIONBIO, &on);
	ioctl(p, TIOCPKT, &on);
	signal(SIGTSTP, SIG_IGN);
	signal(SIGCHLD, cleanup);
	setpgrp(0, 0);
	protocol(f, p);
	signal(SIGCHLD, SIG_IGN);
	cleanup();
}

char	magic[2] = { 0377, 0377 };
char	oobdata[] = {TIOCPKT_WINDOW};

/*
 * Handle a "control" request (signaled by magic being present)
 * in the data stream.  For now, we are only willing to handle
 * window size changes.
 */
control(pty, cp, n)
	int pty;
	char *cp;
	int n;
{
	struct winsize w;

	if (n < 4+sizeof (w) || cp[2] != 's' || cp[3] != 's')
		return (0);
	oobdata[0] &= ~TIOCPKT_WINDOW;	/* we know he heard */
	bcopy(cp+4, (char *)&w, sizeof(w));
	w.ws_row = ntohs(w.ws_row);
	w.ws_col = ntohs(w.ws_col);
	w.ws_xpixel = ntohs(w.ws_xpixel);
	w.ws_ypixel = ntohs(w.ws_ypixel);
	(void)ioctl(pty, TIOCSWINSZ, &w);
	return (4+sizeof (w));
}

/*
 * rlogin "protocol" machine.
 */
protocol(f, p)
	int f, p;
{
	char pibuf[1024], fibuf[1024], *pbp, *fbp;
	register pcc = 0, fcc = 0;
	int cc;
	char cntl;

	/*
	 * Must ignore SIGTTOU, otherwise we'll stop
	 * when we try and set slave pty's window shape
	 * (our controlling tty is the master pty).
	 */
	(void) signal(SIGTTOU, SIG_IGN);
	send(f, oobdata, 1, MSG_OOB);	/* indicate new rlogin */
	for (;;) {
		int ibits, obits, ebits;

		ibits = 0;
		obits = 0;
		if (fcc)
			obits |= (1<<p);
		else
			ibits |= (1<<f);
		if (pcc >= 0)
			if (pcc)
				obits |= (1<<f);
			else
				ibits |= (1<<p);
		ebits = (1<<p);
		if (select(16, &ibits, &obits, &ebits, 0) < 0) {
			if (errno == EINTR)
				continue;
			fatalperror(f, "select");
		}
		if (ibits == 0 && obits == 0 && ebits == 0) {
			/* shouldn't happen... */
			sleep(5);
			continue;
		}
#define	pkcontrol(c)	((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))
		if (ebits & (1<<p)) {
			cc = read(p, &cntl, 1);
			if (cc == 1 && pkcontrol(cntl)) {
				cntl |= oobdata[0];
				send(f, &cntl, 1, MSG_OOB);
				if (cntl & TIOCPKT_FLUSHWRITE) {
					pcc = 0;
					ibits &= ~(1<<p);
				}
			}
		}
		if (ibits & (1<<f)) {
			fcc = read(f, fibuf, sizeof (fibuf));
			if (fcc < 0 && errno == EWOULDBLOCK)
				fcc = 0;
			else {
				register char *cp;
				int left, n;

				if (fcc <= 0)
					break;
				fbp = fibuf;

			top:
				for (cp = fibuf; cp < fibuf+fcc-1; cp++)
					if (cp[0] == magic[0] &&
					    cp[1] == magic[1]) {
						left = fcc - (cp-fibuf);
						n = control(p, cp, left);
						if (n) {
							left -= n;
							if (left > 0)
								bcopy(cp+n, cp, left);
							fcc -= n;
							goto top; /* n^2 */
						}
					}
			}
		}

		if ((obits & (1<<p)) && fcc > 0) {
			cc = write(p, fbp, fcc);
			if (cc > 0) {
				fcc -= cc;
				fbp += cc;
			}
		}

		if (ibits & (1<<p)) {
			pcc = read(p, pibuf, sizeof (pibuf));
			pbp = pibuf;
			if (pcc < 0 && errno == EWOULDBLOCK)
				pcc = 0;
			else if (pcc <= 0)
				break;
			else if (pibuf[0] == 0)
				pbp++, pcc--;
			else {
				if (pkcontrol(pibuf[0])) {
					pibuf[0] |= oobdata[0];
					send(f, &pibuf[0], 1, MSG_OOB);
				}
				pcc = 0;
			}
		}
		if ((obits & (1<<f)) && pcc > 0) {
			cc = write(f, pbp, pcc);
			if (cc < 0 && errno == EWOULDBLOCK) {
				/* also shouldn't happen */
				sleep(5);
				continue;
			}
			if (cc > 0) {
				pcc -= cc;
				pbp += cc;
			}
		}
	}
}

cleanup()
{
	char *p;

	p = line + sizeof("/dev/") - 1;
	if (logout(p))
		logwtmp(p, "", "");
	(void)chmod(line, 0666);
	(void)chown(line, 0, 0);
	*p = 'p';
	(void)chmod(line, 0666);
	(void)chown(line, 0, 0);
	shutdown(netf, 2);
	exit(1);
}

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

	buf[0] = '\01';		/* error indicator */
	(void) sprintf(buf + 1, "rlogind: %s.\r\n", msg);
	(void) write(f, buf, strlen(buf));
	exit(1);
}

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

	if ((unsigned)errno < sys_nerr)
		(void) sprintf(buf, "%s: %s", msg, sys_errlist[errno]);
	else
		(void) sprintf(buf, "%s: Error %d", msg, errno);
	fatal(f, buf);
}