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I forgot Dave Borman's change to keep options up to date (arghh!).
[unix-history] / usr / src / libexec / telnetd / telnetd.c
/*
* 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[] = "@(#)telnetd.c 5.11 (Berkeley) %G%";
#endif not lint
/*
* Stripped-down telnet server.
*/
#include <sys/types.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>
#define BELL '\07'
#define BANNER "\r\n\r\n4.3 BSD UNIX (%s)\r\n\r\r\n\r%s"
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;
char netobuf[BUFSIZ], *nfrontp = netobuf, *nbackp = netobuf;
char *neturg = 0; /* one past last bye of urgent data */
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 */
gotDM; /* when did we last see a data mark */
} clocks;
#define settimer(x) clocks.x = clocks.system++
\f
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) */
openlog("telnetd", LOG_PID | LOG_ODELAY, LOG_DAEMON);
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 *envinit[] = { "TERM=network", 0 };
int cleanup();
/*
* 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;
char c;
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[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);
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);
environ = envinit;
execl("/bin/login", "login", "-h", host, 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;
}
}
\f
/*
* Main loop. Select from pty and network, and
* hand data to telnet receiver finite state machine.
*/
telnet(f, p)
{
int on = 1;
char hostname[32];
net = f, pty = p;
ioctl(f, FIONBIO, &on);
ioctl(p, FIONBIO, &on);
signal(SIGTSTP, SIG_IGN);
signal(SIGCHLD, cleanup);
setpgrp(0, 0);
/*
* Request to do remote echo and to suppress go ahead.
*/
dooption(TELOPT_ECHO);
dooption(TELOPT_SGA);
/*
* Show banner that getty never gave.
*/
gethostname(hostname, sizeof (hostname));
sprintf(nfrontp, BANNER, hostname, "");
nfrontp += strlen(nfrontp);
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(5);
continue;
}
/*
* Any urgent data?
*/
if (FD_ISSET(net, &xbits)) {
SYNCHing = 1;
}
/*
* Something to read from the network...
*/
if (FD_ISSET(net, &ibits)) {
#if !defined(IOCTL_TO_DO_UNIX_OOB_IN_TCP_WAY)
/*
* In 4.2 (and some early 4.3) systems, the
* OOB indication and data handling in the kernel
* is such that if two separate TCP Urgent requests
* come in, one byte of TCP data will be overlaid.
* This is fatal for Telnet, but we try to live
* with it.
*
* In addition, in 4.2 (and...), a special protocol
* is needed to pick up the TCP Urgent data in
* the correct sequence.
*
* What we do is: if we think we are in urgent
* mode, we look to see if we are "at the mark".
* If we are, we do an OOB receive. If we run
* this twice, we will do the OOB receive twice,
* but the second will fail, since the second
* time we were "at the mark", but there wasn't
* any data there (the kernel doesn't reset
* "at the mark" until we do a normal read).
* Once we've read the OOB data, we go ahead
* and do normal reads.
*
* There is also another problem, which is that
* since the OOB byte we read doesn't put us
* out of OOB state, and since that byte is most
* likely the TELNET DM (data mark), we would
* stay in the TELNET SYNCH (SYNCHing) state.
* So, clocks to the rescue. If we've "just"
* received a DM, then we test for the
* presence of OOB data when the receive OOB
* fails (and AFTER we did the normal mode read
* to clear "at the mark").
*/
if (SYNCHing) {
int atmark;
ioctl(net, SIOCATMARK, (char *)&atmark);
if (atmark) {
ncc = recv(net, netibuf, sizeof (netibuf), MSG_OOB);
if ((ncc == -1) && (errno == EINVAL)) {
ncc = read(net, netibuf, sizeof (netibuf));
if (clocks.didnetreceive < clocks.gotDM) {
SYNCHing = stilloob(net);
}
}
} else {
ncc = read(net, netibuf, sizeof (netibuf));
}
} else {
ncc = read(net, netibuf, sizeof (netibuf));
}
settimer(didnetreceive);
#else /* !defined(IOCTL_TO_DO_UNIX_OOB_IN_TCP_WAY) */
ncc = read(net, netibuf, sizeof (netibuf));
#endif /* !defined(IOCTL_TO_DO_UNIX_OOB_IN_TCP_WAY) */
if (ncc < 0 && errno == EWOULDBLOCK)
ncc = 0;
else {
if (ncc <= 0) {
break;
}
netip = netibuf;
}
}
/*
* Something to read from the pty...
*/
if (FD_ISSET(p, &ibits)) {
pcc = read(p, ptyibuf, BUFSIZ);
if (pcc < 0 && errno == EWOULDBLOCK)
pcc = 0;
else {
if (pcc <= 0)
break;
ptyip = ptyibuf;
}
}
while (pcc > 0) {
if ((&netobuf[BUFSIZ] - nfrontp) < 2)
break;
c = *ptyip++ & 0377, pcc--;
if (c == IAC)
*nfrontp++ = c;
*nfrontp++ = c;
if (c == '\r') {
if (pcc > 0 && ((*ptyip & 0377) == '\n')) {
*nfrontp++ = *ptyip++ & 0377;
pcc--;
} else
*nfrontp++ = '\0';
}
}
if (FD_ISSET(f, &obits) && (nfrontp - nbackp) > 0)
netflush();
if (ncc > 0)
telrcv();
if (FD_ISSET(p, &obits) && (pfrontp - pbackp) > 0)
ptyflush();
}
cleanup();
}
/*
* State for recv fsm
*/
#define TS_DATA 0 /* base state */
#define TS_IAC 1 /* look for double IAC's */
#define TS_CR 2 /* CR-LF ->'s CR */
#define TS_BEGINNEG 3 /* throw away begin's... */
#define TS_ENDNEG 4 /* ...end's (suboption negotiation) */
#define TS_WILL 5 /* will option negotiation */
#define TS_WONT 6 /* wont " */
#define TS_DO 7 /* do " */
#define TS_DONT 8 /* dont " */
telrcv()
{
register int c;
static int state = TS_DATA;
while (ncc > 0) {
if ((&ptyobuf[BUFSIZ] - pfrontp) < 2)
return;
c = *netip++ & 0377, ncc--;
switch (state) {
case TS_CR:
state = TS_DATA;
if ((c == 0) || (c == '\n')) {
break;
}
/* FALL THROUGH */
case TS_DATA:
if (c == IAC) {
state = TS_IAC;
break;
}
if (inter > 0)
break;
/*
* We map \r\n ==> \n, since \r\n says
* that we want to be in column 1 of the next
* printable line, and \n is the standard
* unix way of saying that (\r is only good
* if CRMOD is set, which it normally is).
*/
if (!myopts[TELOPT_BINARY] && c == '\r') {
if ((ncc > 0) && ('\n' == *netip)) {
netip++; ncc--;
c = '\n';
} else {
state = TS_CR;
}
}
*pfrontp++ = c;
break;
case TS_IAC:
switch (c) {
/*
* Send the process on the pty side an
* interrupt. Do this with a NULL or
* interrupt char; depending on the tty mode.
*/
case BREAK:
case IP:
interrupt();
break;
/*
* Are You There?
*/
case AYT:
strcpy(nfrontp, "\r\n[Yes]\r\n");
nfrontp += 9;
break;
/*
* Abort Output
*/
case AO: {
struct ltchars tmpltc;
ptyflush(); /* half-hearted */
ioctl(pty, TIOCGLTC, &tmpltc);
if (tmpltc.t_flushc != '\377') {
*pfrontp++ = tmpltc.t_flushc;
}
*nfrontp++ = IAC;
*nfrontp++ = DM;
neturg = nfrontp-1; /* off by one XXX */
break;
}
/*
* Erase Character and
* Erase Line
*/
case EC:
case EL: {
struct sgttyb b;
char ch;
ptyflush(); /* half-hearted */
ioctl(pty, TIOCGETP, &b);
ch = (c == EC) ?
b.sg_erase : b.sg_kill;
if (ch != '\377') {
*pfrontp++ = ch;
}
break;
}
/*
* Check for urgent data...
*/
case DM:
SYNCHing = stilloob(net);
settimer(gotDM);
break;
/*
* Begin option subnegotiation...
*/
case SB:
state = TS_BEGINNEG;
continue;
case WILL:
state = TS_WILL;
continue;
case WONT:
state = TS_WONT;
continue;
case DO:
state = TS_DO;
continue;
case DONT:
state = TS_DONT;
continue;
case IAC:
*pfrontp++ = c;
break;
}
state = TS_DATA;
break;
case TS_BEGINNEG:
if (c == IAC)
state = TS_ENDNEG;
break;
case TS_ENDNEG:
state = c == SE ? TS_DATA : TS_BEGINNEG;
break;
case TS_WILL:
if (!hisopts[c])
willoption(c);
state = TS_DATA;
continue;
case TS_WONT:
if (hisopts[c])
wontoption(c);
state = TS_DATA;
continue;
case TS_DO:
if (!myopts[c])
dooption(c);
state = TS_DATA;
continue;
case TS_DONT:
if (myopts[c]) {
myopts[c] = 0;
sprintf(nfrontp, wont, c);
nfrontp += sizeof (wont) - 2;
}
state = TS_DATA;
continue;
default:
printf("telnetd: panic state=%d\n", state);
exit(1);
}
}
}
willoption(option)
int option;
{
char *fmt;
switch (option) {
case TELOPT_BINARY:
mode(RAW, 0);
fmt = doopt;
break;
case TELOPT_ECHO:
mode(0, ECHO|CRMOD);
fmt = doopt;
break;
case TELOPT_SGA:
fmt = doopt;
break;
case TELOPT_TM:
fmt = dont;
break;
default:
fmt = dont;
break;
}
if (fmt == doopt) {
hisopts[option] = 1;
} else {
hisopts[option] = 0;
}
sprintf(nfrontp, fmt, option);
nfrontp += sizeof (dont) - 2;
}
wontoption(option)
int option;
{
char *fmt;
switch (option) {
case TELOPT_ECHO:
mode(ECHO|CRMOD, 0);
break;
case TELOPT_BINARY:
mode(0, RAW);
break;
}
fmt = dont;
hisopts[option] = 0;
sprintf(nfrontp, fmt, option);
nfrontp += sizeof (doopt) - 2;
}
dooption(option)
int option;
{
char *fmt;
switch (option) {
case TELOPT_TM:
fmt = wont;
break;
case TELOPT_ECHO:
mode(ECHO|CRMOD, 0);
fmt = will;
break;
case TELOPT_BINARY:
mode(RAW, 0);
fmt = will;
break;
case TELOPT_SGA:
fmt = will;
break;
default:
fmt = wont;
break;
}
if (fmt == will) {
myopts[option] = 1;
} else {
myopts[option] = 0;
}
sprintf(nfrontp, fmt, option);
nfrontp += sizeof (doopt) - 2;
}
mode(on, off)
int on, off;
{
struct sgttyb b;
ptyflush();
ioctl(pty, TIOCGETP, &b);
b.sg_flags |= on;
b.sg_flags &= ~off;
ioctl(pty, TIOCSETP, &b);
}
/*
* Send interrupt to process on other side of pty.
* If it is in raw mode, just write NULL;
* otherwise, write intr char.
*/
interrupt()
{
struct sgttyb b;
struct tchars tchars;
ptyflush(); /* half-hearted */
ioctl(pty, TIOCGETP, &b);
if (b.sg_flags & RAW) {
*pfrontp++ = '\0';
return;
}
*pfrontp++ = ioctl(pty, TIOCGETC, &tchars) < 0 ?
'\177' : tchars.t_intrc;
}
ptyflush()
{
int n;
if ((n = pfrontp - pbackp) > 0)
n = write(pty, pbackp, n);
if (n < 0)
return;
pbackp += n;
if (pbackp == pfrontp)
pbackp = pfrontp = ptyobuf;
}
#if 0
netflush()
{
int n;
if ((n = nfrontp - nbackp) > 0)
n = write(net, nbackp, n);
if (n < 0) {
if (errno == EWOULDBLOCK)
return;
/* should blow this guy away... */
return;
}
nbackp += n;
if (nbackp == nfrontp)
nbackp = nfrontp = netobuf;
}
#else /* 0 */
/*
* netflush
* Send as much data as possible to the network,
* handling requests for urgent data.
*/
netflush()
{
int n;
if ((n = nfrontp - nbackp) > 0) {
if (!neturg) {
n = write(net, nbackp, n); /* normal write */
} else {
n = neturg - nbackp;
/*
* In 4.2 (and 4.3) systems, there is some question about
* what byte in a sendOOB operation is the "OOB" data.
* To make ourselves compatible, we only send ONE byte
* out of band, the one WE THINK should be OOB (though
* we really have more the TCP philosophy of urgent data
* rather than the Unix philosophy of OOB data).
*/
if (n > 1) {
n = send(net, nbackp, n-1, 0); /* send URGENT all by itself */
} else {
n = send(net, nbackp, n, MSG_OOB); /* URGENT data */
}
}
}
if (n < 0) {
if (errno == EWOULDBLOCK)
return;
/* should blow this guy away... */
return;
}
nbackp += n;
if (nbackp >= neturg) {
neturg = 0;
}
if (nbackp == nfrontp) {
nbackp = nfrontp = netobuf;
}
}
#endif /* 0 */
cleanup()
{
rmut();
vhangup(); /* XXX */
shutdown(net, 2);
exit(1);
}
#include <utmp.h>
struct utmp wtmp;
char wtmpf[] = "/usr/adm/wtmp";
char utmpf[] = "/etc/utmp";
#define SCPYN(a, b) strncpy(a, b, sizeof(a))
#define SCMPN(a, b) strncmp(a, b, sizeof(a))
rmut()
{
register f;
int found = 0;
struct utmp *u, *utmp;
int nutmp;
struct stat statbf;
f = open(utmpf, O_RDWR);
if (f >= 0) {
fstat(f, &statbf);
utmp = (struct utmp *)malloc(statbf.st_size);
if (!utmp)
syslog(LOG_ERR, "utmp malloc failed");
if (statbf.st_size && utmp) {
nutmp = read(f, utmp, statbf.st_size);
nutmp /= sizeof(struct utmp);
for (u = utmp ; u < &utmp[nutmp] ; u++) {
if (SCMPN(u->ut_line, line+5) ||
u->ut_name[0]==0)
continue;
lseek(f, ((long)u)-((long)utmp), L_SET);
SCPYN(u->ut_name, "");
SCPYN(u->ut_host, "");
time(&u->ut_time);
write(f, (char *)u, sizeof(wtmp));
found++;
}
}
close(f);
}
if (found) {
f = open(wtmpf, O_WRONLY|O_APPEND);
if (f >= 0) {
SCPYN(wtmp.ut_line, line+5);
SCPYN(wtmp.ut_name, "");
SCPYN(wtmp.ut_host, "");
time(&wtmp.ut_time);
write(f, (char *)&wtmp, sizeof(wtmp));
close(f);
}
}
chmod(line, 0666);
chown(line, 0, 0);
line[strlen("/dev/")] = 'p';
chmod(line, 0666);
chown(line, 0, 0);
}
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.