/*
 * Copyright (c) 1989 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static char sccsid[] = "@(#)utility.c	5.1 (Berkeley) 09/01/89";
#endif /* not lint */


#include "telnetd.h"

/*
 * utility functions performing io related tasks
 */

/*
 * 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()
{
    void netflush();

    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();
    }
}  /* end of ttloop */

/*
 * 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");
    }
    if (FD_ISSET(s, &excepts)) {
	return 1;
    } else {
	return 0;
    }
}

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;
}

/*
 * nextitem()
 *
 *	Return the address of the next "item" in the TELNET data
 * stream.  This will be the address of the next character if
 * the current address is a user data character, or it will
 * be the address of the character following the TELNET command
 * if the current address is a TELNET IAC ("I Am a Command")
 * character.
 */
char *
nextitem(current)
char	*current;
{
    if ((*current&0xff) != IAC) {
	return current+1;
    }
    switch (*(current+1)&0xff) {
    case DO:
    case DONT:
    case WILL:
    case WONT:
	return current+3;
    case SB:		/* loop forever looking for the SE */
	{
	    register char *look = current+2;

	    for (;;) {
		if ((*look++&0xff) == IAC) {
		    if ((*look++&0xff) == SE) {
			return look;
		    }
		}
	    }
	}
    default:
	return current+2;
    }
}  /* end of nextitem */


/*
 * netclear()
 *
 *	We are about to do a TELNET SYNCH operation.  Clear
 * the path to the network.
 *
 *	Things are a bit tricky since we may have sent the first
 * byte or so of a previous TELNET command into the network.
 * So, we have to scan the network buffer from the beginning
 * until we are up to where we want to be.
 *
 *	A side effect of what we do, just to keep things
 * simple, is to clear the urgent data pointer.  The principal
 * caller should be setting the urgent data pointer AFTER calling
 * us in any case.
 */
netclear()
{
    register char *thisitem, *next;
    char *good;
#define	wewant(p)	((nfrontp > p) && ((*p&0xff) == IAC) && \
				((*(p+1)&0xff) != EC) && ((*(p+1)&0xff) != EL))

    thisitem = netobuf;

    while ((next = nextitem(thisitem)) <= nbackp) {
	thisitem = next;
    }

    /* Now, thisitem is first before/at boundary. */

    good = netobuf;	/* where the good bytes go */

    while (nfrontp > thisitem) {
	if (wewant(thisitem)) {
	    int length;

	    next = thisitem;
	    do {
		next = nextitem(next);
	    } while (wewant(next) && (nfrontp > next));
	    length = next-thisitem;
	    bcopy(thisitem, good, length);
	    good += length;
	    thisitem = next;
	} else {
	    thisitem = nextitem(thisitem);
	}
    }

    nbackp = netobuf;
    nfrontp = good;		/* next byte to be sent */
    neturg = 0;
}  /* end of netclear */

/*
 *  netflush
 *		Send as much data as possible to the network,
 *	handling requests for urgent data.
 */
void
netflush()
{
    int n;
    extern int not42;

    if ((n = nfrontp - nbackp) > 0) {
	/*
	 * if no urgent data, or if the other side appears to be an
	 * old 4.2 client (and thus unable to survive TCP urgent data),
	 * write the entire buffer in non-OOB mode.
	 */
	if ((neturg == 0) || (not42 == 0)) {
	    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 || errno == EINTR)
		return;
	cleanup();
    }
    nbackp += n;
    if (nbackp >= neturg) {
	neturg = 0;
    }
    if (nbackp == nfrontp) {
	nbackp = nfrontp = netobuf;
    }
    return;
}  /* end of netflush */


/*
 * writenet
 *
 * Just a handy little function to write a bit of raw data to the net.
 * It will force a transmit of the buffer if necessary
 *
 * arguments
 *    ptr - A pointer to a character string to write
 *    len - How many bytes to write
 */
writenet(ptr, len)
register char *ptr;
register int len;
{
	/* flush buffer if no room for new data) */
	if ((&netobuf[BUFSIZ] - nfrontp) < len) {
		/* if this fails, don't worry, buffer is a little big */
		netflush();
	}

	bcopy(ptr, nfrontp, len);
	nfrontp += len;

}  /* end of writenet */


/*
 * miscellaneous functions doing a variety of little jobs follow ...
 */


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

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

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

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

char editedhost[32];

edithost(pat, host)
	register char *pat;
	register char *host;
{
	register char *res = editedhost;
	char *strncpy();

	if (!pat)
		pat = "";
	while (*pat) {
		switch (*pat) {

		case '#':
			if (*host)
				host++;
			break;

		case '@':
			if (*host)
				*res++ = *host++;
			break;

		default:
			*res++ = *pat;
			break;
		}
		if (res == &editedhost[sizeof editedhost - 1]) {
			*res = '\0';
			return;
		}
		pat++;
	}
	if (*host)
		(void) strncpy(res, host,
				sizeof editedhost - (res - editedhost) -1);
	else
		*res = '\0';
	editedhost[sizeof editedhost - 1] = '\0';
}

static char *putlocation;

putstr(s)
register char *s;
{

	while (*s)
		putchr(*s++);
}

putchr(cc)
{
	*putlocation++ = cc;
}

putf(cp, where)
register char *cp;
char *where;
{
	char *slash;
#ifndef	NO_GETTYTAB
	char datebuffer[60];
#endif	/* NO_GETTYTAB */
	extern char *rindex();

	putlocation = where;

	while (*cp) {
		if (*cp != '%') {
			putchr(*cp++);
			continue;
		}
		switch (*++cp) {

		case 't':
			slash = rindex(line, '/');
			if (slash == (char *) 0)
				putstr(line);
			else
				putstr(&slash[1]);
			break;

		case 'h':
			putstr(editedhost);
			break;

#ifndef	NO_GETTYTAB
		case 'd':
			get_date(datebuffer);
			putstr(datebuffer);
			break;
#endif	/* NO_GETTYTAB */

		case '%':
			putchr('%');
			break;
		}
		cp++;
	}
}

/*ARGSUSED*/
#ifdef	NO_GETTYTAB
getent(cp, name)
char *cp, *name;
{
	return(0);
}

/*ARGSUSED*/
char *
getstr(cp, cpp)
char *cp, **cpp;
{
	return(0);
}
#endif	/* NO_GETTYTAB */