telnetdaaa.c

经典的unix下telnetd代码

	init_termdriver(f, p, interrupt, sendbrk);
#endif

#if	defined(SO_OOBINLINE)
	(void) setsockopt(net, SOL_SOCKET, SO_OOBINLINE,
				(char *)&on, sizeof on);
#endif	/* defined(SO_OOBINLINE) */

#ifdef	SIGTSTP
	(void) signal(SIGTSTP, SIG_IGN);
#endif
#ifdef	SIGTTOU
	/*
	 * Ignoring SIGTTOU keeps the kernel from blocking us
	 * in ttioct() in /sys/tty.c.
	 */
	(void) signal(SIGTTOU, SIG_IGN);
#endif

	(void) signal(SIGCHLD, cleanup);

#if	defined(CRAY2) && defined(UNICOS5)
	/*
	 * Cray-2 will send a signal when pty modes are changed by slave
	 * side.  Set up signal handler now.
	 */
	if ((int)signal(SIGUSR1, termstat) < 0)
		perror("signal");
	else if (ioctl(p, TCSIGME, (char *)SIGUSR1) < 0)
		perror("ioctl:TCSIGME");
	/*
	 * Make processing loop check terminal characteristics early on.
	 */
	termstat();
#endif

#ifdef  TIOCNOTTY
	{
		register int t;
		t = open(_PATH_TTY, O_RDWR);
		if (t >= 0) {
			(void) ioctl(t, TIOCNOTTY, (char *)0);
			(void) close(t);
		}
	}
#endif

#if	defined(CRAY) && defined(NEWINIT) && defined(TIOCSCTTY)
	(void) setsid();
	ioctl(p, TIOCSCTTY, 0);
#endif

	/*
	 * Show banner that getty never gave.
	 *
	 * We put the banner in the pty input buffer.  This way, it
	 * gets carriage return null processing, etc., just like all
	 * other pty --> client data.
	 */

#if	!defined(CRAY) || !defined(NEWINIT)
	if (getenv("USER"))
		hostinfo = 0;
#endif

	if (getent(defent, "default") == 1) {
		char *Getstr();
		char *cp=defstrs;

		HE = Getstr("he", &cp);
		HN = Getstr("hn", &cp);
		IM = Getstr("im", &cp);
		if (HN && *HN) {
			(void) strncpy(host_name, HN, sizeof(host_name)-1);
			hostname[sizeof(host_name)-1] = '\0';
		}
		if (IM == 0)
			IM = "";
	} else {
		IM = DEFAULT_IM;
		HE = 0;
	}
	edithost(HE, host_name);
	if (hostinfo && *IM)
		putf(IM, ptyibuf2);

	if (pcc)
		(void) strncat(ptyibuf2, ptyip, pcc+1);
	ptyip = ptyibuf2;
	pcc = strlen(ptyip);
#ifdef	LINEMODE
	/*
	 * Last check to make sure all our states are correct.
	 */
	init_termbuf();
	localstat();
#endif	/* LINEMODE */

	DIAG(TD_REPORT,
		{sprintf(nfrontp, "td: Entering processing loop\r\n");
		 nfrontp += strlen(nfrontp);});

#ifdef	convex
	startslave(host);
#endif

	nfd = ((f > p) ? f : p) + 1;
	for (;;) {
		fd_set ibits, obits, xbits;
		register int c;

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

#if	defined(CRAY2) && defined(UNICOS5)
		if (needtermstat)
			_termstat();
#endif	/* defined(CRAY2) && defined(UNICOS5) */
		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(nfd, &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(SO_OOBINLINE)
			/*
			 * In 4.2 (and 4.3 beta) 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;

			(void) 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 (sequenceIs(didnetreceive, gotDM)) {
				    SYNCHing = stilloob(net);
				}
			    }
			} else {
			    ncc = read(net, netibuf, sizeof (netibuf));
			}
		    } else {
			ncc = read(net, netibuf, sizeof (netibuf));
		    }
		    settimer(didnetreceive);
#else	/* !defined(SO_OOBINLINE)) */
		    ncc = read(net, netibuf, sizeof (netibuf));
#endif	/* !defined(SO_OOBINLINE)) */
		    if (ncc < 0 && errno == EWOULDBLOCK)
			ncc = 0;
		    else {
			if (ncc <= 0) {
			    break;
			}
			netip = netibuf;
		    }
		    DIAG((TD_REPORT | TD_NETDATA),
			    {sprintf(nfrontp, "td: netread %d chars\r\n", ncc);
			     nfrontp += strlen(nfrontp);});
		    DIAG(TD_NETDATA, printdata("nd", netip, ncc));
		}

		/*
		 * Something to read from the pty...
		 */
		if (FD_ISSET(p, &ibits)) {
#ifndef	STREAMSPTY
			pcc = read(p, ptyibuf, BUFSIZ);
#else
			pcc = readstream(p, ptyibuf, BUFSIZ);
#endif
			/*
			 * On some systems, if we try to read something
			 * off the master side before the slave side is
			 * opened, we get EIO.
			 */
			if (pcc < 0 && (errno == EWOULDBLOCK ||
#ifdef	EAGAIN
					errno == EAGAIN ||
#endif
					errno == EIO)) {
				pcc = 0;
			} else {
				if (pcc <= 0)
					break;
#if	!defined(CRAY2) || !defined(UNICOS5)
#ifdef	LINEMODE
				/*
				 * If ioctl from pty, pass it through net
				 */
				if (ptyibuf[0] & TIOCPKT_IOCTL) {
					copy_termbuf(ptyibuf+1, pcc-1);
					localstat();
					pcc = 1;
				}
#endif	/* LINEMODE */
				if (ptyibuf[0] & TIOCPKT_FLUSHWRITE) {
					netclear();	/* clear buffer back */
#ifndef	NO_URGENT
					/*
					 * There are client telnets on some
					 * operating systems get screwed up
					 * royally if we send them urgent
					 * mode data.
					 */
					*nfrontp++ = IAC;
					*nfrontp++ = DM;
					neturg = nfrontp-1; /* off by one XXX */
					DIAG(TD_OPTIONS,
					    printoption("td: send IAC", DM));

#endif
				}
				if (his_state_is_will(TELOPT_LFLOW) &&
				    (ptyibuf[0] &
				     (TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))) {
					int newflow =
					    ptyibuf[0] & TIOCPKT_DOSTOP ? 1 : 0;
					if (newflow != flowmode) {
						flowmode = newflow;
						(void) sprintf(nfrontp,
							"%c%c%c%c%c%c",
							IAC, SB, TELOPT_LFLOW,
							flowmode ? LFLOW_ON
								 : LFLOW_OFF,
							IAC, SE);
						nfrontp += 6;
						DIAG(TD_OPTIONS, printsub('>',
						    (unsigned char *)nfrontp-4,
						    4););
					}
				}
				pcc--;
				ptyip = ptyibuf+1;
#else	/* defined(CRAY2) && defined(UNICOS5) */
				if (!uselinemode) {
					unpcc = pcc;
					unptyip = ptyibuf;
					pcc = term_output(&unptyip, ptyibuf2,
								&unpcc, BUFSIZ);
					ptyip = ptyibuf2;
				} else
					ptyip = ptyibuf;
#endif	/* defined(CRAY2) && defined(UNICOS5) */
			}
		}

		while (pcc > 0) {
			if ((&netobuf[BUFSIZ] - nfrontp) < 2)
				break;
			c = *ptyip++ & 0377, pcc--;
			if (c == IAC)
				*nfrontp++ = c;
#if	defined(CRAY2) && defined(UNICOS5)
			else if (c == '\n' &&
				     my_state_is_wont(TELOPT_BINARY) && newmap)
				*nfrontp++ = '\r';
#endif	/* defined(CRAY2) && defined(UNICOS5) */
			*nfrontp++ = c;
			if ((c == '\r') && (my_state_is_wont(TELOPT_BINARY))) {
				if (pcc > 0 && ((*ptyip & 0377) == '\n')) {
					*nfrontp++ = *ptyip++ & 0377;
					pcc--;
				} else
					*nfrontp++ = '\0';
			}
		}
#if	defined(CRAY2) && defined(UNICOS5)
		/*
		 * If chars were left over from the terminal driver,
		 * note their existence.
		 */
		if (!uselinemode && unpcc) {
			pcc = unpcc;
			unpcc = 0;
			ptyip = unptyip;
		}
#endif	/* defined(CRAY2) && defined(UNICOS5) */

		if (FD_ISSET(f, &obits) && (nfrontp - nbackp) > 0)
			netflush();
		if (ncc > 0)
			telrcv();
		if (FD_ISSET(p, &obits) && (pfrontp - pbackp) > 0)
			ptyflush();
	}
	cleanup(0);
}  /* end of telnet */

#ifndef	TCSIG
# ifdef	TIOCSIG
#  define TCSIG TIOCSIG
# endif
#endif

#ifdef	STREAMSPTY

int flowison = -1;  /* current state of flow: -1 is unknown */

int readstream(p, ibuf, bufsize)
	int p;
	char *ibuf;
	int bufsize;
{
	int flags = 0;
	int ret = 0;
	struct termios *tsp;
	struct termio *tp;
	struct iocblk *ip;
	char vstop, vstart;
	int ixon;
	int newflow;

	strbufc.maxlen = BUFSIZ;
	strbufc.buf = (char *)ctlbuf;
	strbufd.maxlen = bufsize-1;
	strbufd.len = 0;
	strbufd.buf = ibuf+1;
	ibuf[0] = 0;

	ret = getmsg(p, &strbufc, &strbufd, &flags);
	if (ret < 0)  /* error of some sort -- probably EAGAIN */
		return(-1);

	if (strbufc.len <= 0 || ctlbuf[0] == M_DATA) {
		/* data message */
		if (strbufd.len > 0) {			/* real data */
			return(strbufd.len + 1);	/* count header char */
		} else {
			/* nothing there */
			errno = EAGAIN;
			return(-1);
		}
	}

	/*
	 * It's a control message.  Return 1, to look at the flag we set
	 */

	switch (ctlbuf[0]) {
	case M_FLUSH:
		if (ibuf[1] & FLUSHW)
			ibuf[0] = TIOCPKT_FLUSHWRITE;
		return(1);

	case M_IOCTL:
		ip = (struct iocblk *) (ibuf+1);

		switch (ip->ioc_cmd) {
		case TCSETS:
		case TCSETSW:
		case TCSETSF:
			tsp = (struct termios *)
					(ibuf+1 + sizeof(struct iocblk));
			vstop = tsp->c_cc[VSTOP];
			vstart = tsp->c_cc[VSTART];
			ixon = tsp->c_iflag & IXON;
			break;
		case TCSETA:
		case TCSETAW:
		case TCSETAF:
			tp = (struct termio *) (ibuf+1 + sizeof(struct iocblk));
			vstop = tp->c_cc[VSTOP];
			vstart = tp->c_cc[VSTART];
			ixon = tp->c_iflag & IXON;
			break;
		default:
			errno = EAGAIN;
			return(-1);
		}

		newflow =  (ixon && (vstart == 021) && (vstop == 023)) ? 1 : 0;
		if (newflow != flowison) {  /* it's a change */
			flowison = newflow;
			ibuf[0] = newflow ? TIOCPKT_DOSTOP : TIOCPKT_NOSTOP;
			return(1);
		}
	}

	/* nothing worth doing anything about */
	errno = EAGAIN;
	return(-1);
}
#endif /* STREAMSPTY */

/*
 * Send interrupt to process on other side of pty.
 * If it is in raw mode, just write NULL;
 * otherwise, write intr char.
 */
	void
interrupt()
{
	ptyflush();	/* half-hearted */

#if defined(STREAMSPTY) && defined(TIOCSIGNAL)
	/* Streams PTY style ioctl to post a signal */
	{
		int sig = SIGINT;
		(void) ioctl(pty, TIOCSIGNAL, &sig);
		(void) ioctl(pty, I_FLUSH, FLUSHR);
	}
#else
#ifdef	TCSIG
	(void) ioctl(pty, TCSIG, (char *)SIGINT);
#else	/* TCSIG */
	init_termbuf();
	*pfrontp++ = slctab[SLC_IP].sptr ?
			(unsigned char)*slctab[SLC_IP].sptr : '\177';
#endif	/* TCSIG */
#endif
}

/*
 * Send quit to process on other side of pty.
 * If it is in raw mode, just write NULL;
 * otherwise, write quit char.
 */
	void
sendbrk()
{
	ptyflush();	/* half-hearted */
#ifdef	TCSIG
	(void) ioctl(pty, TCSIG, (char *)SIGQUIT);
#else	/* TCSIG */
	init_termbuf();
	*pfrontp++ = slctab[SLC_ABORT].sptr ?
			(unsigned char)*slctab[SLC_ABORT].sptr : '\034';
#endif	/* TCSIG */
}

	void
sendsusp()
{
#ifdef	SIGTSTP
	ptyflush();	/* half-hearted */
# ifdef	TCSIG
	(void) ioctl(pty, TCSIG, (char *)SIGTSTP);
# else	/* TCSIG */
	*pfrontp++ = slctab[SLC_SUSP].sptr ?
			(unsigned char)*slctab[SLC_SUSP].sptr : '\032';
# endif	/* TCSIG */
#endif	/* SIGTSTP */
}

/*
 * When we get an AYT, if ^T is enabled, use that.  Otherwise,
 * just send back "[Yes]".
 */
	void
recv_ayt()
{
#if	defined(SIGINFO) && defined(TCSIG)
	if (slctab[SLC_AYT].sptr && *slctab[SLC_AYT].sptr != _POSIX_VDISABLE) {
		(void) ioctl(pty, TCSIG, (char *)SIGINFO);
		return;
	}
#endif
	(void) strcpy(nfrontp, "\r\n[Yes]\r\n");
	nfrontp += 9;
}

	void
doeof()
{
	init_termbuf();

#if	defined(LINEMODE) && defined(USE_TERMIO) && (VEOF == VMIN)
	if (!tty_isediting()) {
		extern char oldeofc;
		*pfrontp++ = oldeofc;
		return;
	}
#endif
	*pfrontp++ = slctab[SLC_EOF].sptr ?
			(unsigned char)*slctab[SLC_EOF].sptr : '\004';
}