/*	$FreeBSD: stable/10/usr.sbin/rtadvd/advcap.c 222824 2011-06-07 15:40:17Z hrs $	*/
/*	$KAME: advcap.c,v 1.11 2003/05/19 09:46:50 keiichi Exp $	*/

/*
 * Copyright (c) 1983 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * remcap - routines for dealing with the remote host data base
 *
 * derived from termcap
 */
#include <sys/types.h>
#include <sys/uio.h>
#include <unistd.h>
#include <fcntl.h>
#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>
#include <syslog.h>
#include <errno.h>
#include <string.h>
#include "pathnames.h"

#ifndef BUFSIZ
#define	BUFSIZ		1024
#endif
#define MAXHOP		32		/* max number of tc= indirections */

#define	tgetent		agetent
#define	tnchktc		anchktc
#define	tnamatch	anamatch
#define	tgetnum		agetnum
#define	tgetflag	agetflag
#define	tgetstr		agetstr

#if 0
#define V_TERMCAP	"REMOTE"
#define V_TERM		"HOST"
#endif

/*
 * termcap - routines for dealing with the terminal capability data base
 *
 * BUG:		Should use a "last" pointer in tbuf, so that searching
 *		for capabilities alphabetically would not be a n**2/2
 *		process when large numbers of capabilities are given.
 * Note:	If we add a last pointer now we will screw up the
 *		tc capability. We really should compile termcap.
 *
 * Essentially all the work here is scanning and decoding escapes
 * in string capabilities.  We don't use stdio because the editor
 * doesn't, and because living w/o it is not hard.
 */

static	char *tbuf;
static	int hopcount;	/* detect infinite loops in termcap, init 0 */

extern const char *conffile;

int tgetent(char *, char *);
int getent(char *, char *, const char *);
int tnchktc(void);
int tnamatch(char *);
static char *tskip(char *);
int64_t tgetnum(char *);
int tgetflag(char *);
char *tgetstr(char *, char **);
static char *tdecode(char *, char **);

/*
 * Get an entry for terminal name in buffer bp,
 * from the termcap file.  Parse is very rudimentary;
 * we just notice escaped newlines.
 */
int
tgetent(char *bp, char *name)
{
	return (getent(bp, name, conffile));
}

int
getent(char *bp, char *name, const char *cfile)
{
	int c;
	int i = 0, cnt = 0;
	char ibuf[BUFSIZ];
	char *cp;
	int tf;

	tbuf = bp;
	tf = 0;
	/*
	 * TERMCAP can have one of two things in it. It can be the
	 * name of a file to use instead of /etc/termcap. In this
	 * case it better start with a "/". Or it can be an entry to
	 * use so we don't have to read the file. In this case it
	 * has to already have the newlines crunched out.
	 */
	if (cfile && *cfile)
		tf = open(cfile, O_RDONLY);

	if (tf < 0) {
		syslog(LOG_INFO,
		       "<%s> open: %s", __func__, strerror(errno));
		return (-2);
	}
	for (;;) {
		cp = bp;
		for (;;) {
			if (i == cnt) {
				cnt = read(tf, ibuf, BUFSIZ);
				if (cnt <= 0) {
					close(tf);
					return (0);
				}
				i = 0;
			}
			c = ibuf[i++];
			if (c == '\n') {
				if (cp > bp && cp[-1] == '\\') {
					cp--;
					continue;
				}
				break;
			}
			if (cp >= bp + BUFSIZ) {
				write(STDERR_FILENO, "Remcap entry too long\n",
				      23);
				break;
			} else
				*cp++ = c;
		}
		*cp = 0;

		/*
		 * The real work for the match.
		 */
		if (tnamatch(name)) {
			close(tf);
			return (tnchktc());
		}
	}
}

/*
 * tnchktc: check the last entry, see if it's tc=xxx. If so,
 * recursively find xxx and append that entry (minus the names)
 * to take the place of the tc=xxx entry. This allows termcap
 * entries to say "like an HP2621 but doesn't turn on the labels".
 * Note that this works because of the left to right scan.
 */
int
tnchktc(void)
{
	char *p, *q;
	char tcname[16];	/* name of similar terminal */
	char tcbuf[BUFSIZ];
	char *holdtbuf = tbuf;
	int l;

	p = tbuf + strlen(tbuf) - 2;	/* before the last colon */
	while (*--p != ':')
		if (p < tbuf) {
			write(STDERR_FILENO, "Bad remcap entry\n", 18);
			return (0);
		}
	p++;
	/* p now points to beginning of last field */
	if (p[0] != 't' || p[1] != 'c')
		return (1);
	strlcpy(tcname, p + 3, sizeof tcname);
	q = tcname;
	while (*q && *q != ':')
		q++;
	*q = 0;
	if (++hopcount > MAXHOP) {
		write(STDERR_FILENO, "Infinite tc= loop\n", 18);
		return (0);
	}
	if (getent(tcbuf, tcname, conffile) != 1) {
		return (0);
	}
	for (q = tcbuf; *q++ != ':'; )
		;
	l = p - holdtbuf + strlen(q);
	if (l > BUFSIZ) {
		write(STDERR_FILENO, "Remcap entry too long\n", 23);
		q[BUFSIZ - (p-holdtbuf)] = 0;
	}
	strcpy(p, q);
	tbuf = holdtbuf;
	return (1);
}

/*
 * Tnamatch deals with name matching.  The first field of the termcap
 * entry is a sequence of names separated by |'s, so we compare
 * against each such name.  The normal : terminator after the last
 * name (before the first field) stops us.
 */
int
tnamatch(char *np)
{
	char *Np, *Bp;

	Bp = tbuf;
	if (*Bp == '#')
		return (0);
	for (;;) {
		for (Np = np; *Np && *Bp == *Np; Bp++, Np++)
			continue;
		if (*Np == 0 && (*Bp == '|' || *Bp == ':' || *Bp == 0))
			return (1);
		while (*Bp && *Bp != ':' && *Bp != '|')
			Bp++;
		if (*Bp == 0 || *Bp == ':')
			return (0);
		Bp++;
	}
}

/*
 * Skip to the next field.  Notice that this is very dumb, not
 * knowing about \: escapes or any such.  If necessary, :'s can be put
 * into the termcap file in octal.
 */
static char *
tskip(char *bp)
{
	int dquote;

	dquote = 0;
	while (*bp) {
		switch (*bp) {
		case ':':
			if (!dquote)
				goto breakbreak;
			else
				bp++;
			break;
		case '\\':
			bp++;
			if (isdigit(*bp)) {
				while (isdigit(*bp++))
					;
			} else
				bp++;
		case '"':
			dquote = (dquote ? 1 : 0);
			bp++;
			break;
		default:
			bp++;
			break;
		}
	}
breakbreak:
	if (*bp == ':')
		bp++;
	return (bp);
}

/*
 * Return the (numeric) option id.
 * Numeric options look like
 *	li#80
 * i.e. the option string is separated from the numeric value by
 * a # character.  If the option is not found we return -1.
 * Note that we handle octal numbers beginning with 0.
 */
int64_t
tgetnum(char *id)
{
	int64_t i;
	int base;
	char *bp = tbuf;

	for (;;) {
		bp = tskip(bp);
		if (*bp == 0)
			return (-1);
		if (strncmp(bp, id, strlen(id)) != 0)
			continue;
		bp += strlen(id);
		if (*bp == '@')
			return (-1);
		if (*bp != '#')
			continue;
		bp++;
		base = 10;
		if (*bp == '0')
			base = 8;
		i = 0;
		while (isdigit(*bp))
			i *= base, i += *bp++ - '0';
		return (i);
	}
}

/*
 * Handle a flag option.
 * Flag options are given "naked", i.e. followed by a : or the end
 * of the buffer.  Return 1 if we find the option, or 0 if it is
 * not given.
 */
int
tgetflag(char *id)
{
	char *bp = tbuf;

	for (;;) {
		bp = tskip(bp);
		if (!*bp)
			return (0);
		if (strncmp(bp, id, strlen(id)) == 0) {
			bp += strlen(id);
			if (!*bp || *bp == ':')
				return (1);
			else if (*bp == '@')
				return (0);
		}
	}
}

/*
 * Get a string valued option.
 * These are given as
 *	cl=^Z
 * Much decoding is done on the strings, and the strings are
 * placed in area, which is a ref parameter which is updated.
 * No checking on area overflow.
 */
char *
tgetstr(char *id, char **area)
{
	char *bp = tbuf;

	for (;;) {
		bp = tskip(bp);
		if (!*bp)
			return (0);
		if (strncmp(bp, id, strlen(id)) != 0)
			continue;
		bp += strlen(id);
		if (*bp == '@')
			return (0);
		if (*bp != '=')
			continue;
		bp++;
		return (tdecode(bp, area));
	}
}

/*
 * Tdecode does the grung work to decode the
 * string capability escapes.
 */
static char *
tdecode(char *str, char **area)
{
	char *cp;
	int c;
	const char *dp;
	int i;
	char term;

	term = ':';
	cp = *area;
again:
	if (*str == '"') {
		term = '"';
		str++;
	}
	while ((c = *str++) && c != term) {
		switch (c) {

		case '^':
			c = *str++ & 037;
			break;

		case '\\':
			dp = "E\033^^\\\\::n\nr\rt\tb\bf\f\"\"";
			c = *str++;
nextc:
			if (*dp++ == c) {
				c = *dp++;
				break;
			}
			dp++;
			if (*dp)
				goto nextc;
			if (isdigit(c)) {
				c -= '0', i = 2;
				do
					c <<= 3, c |= *str++ - '0';
				while (--i && isdigit(*str));
			}
			break;
		}
		*cp++ = c;
	}
	if (c == term && term != ':') {
		term = ':';
		goto again;
	}
	*cp++ = 0;
	str = *area;
	*area = cp;
	return (str);
}