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Add 'echo-client-id' statment, so that RFC 6842 behaviour can be
turned off for those clients and networks that find it impossible to
move past RFC 2131. Modelled on the same statement in recent ISC
versions, though we default to 'on' (a.k.a. RFC 6842) rather that
'off' (a.k.a. RFC 2131).

Problems reported by Bastien Durel (Xerox Phaser 6022 printer) and
Bryan Vyhmeister (Hon Hai Precision router) via misc@. Thanks!

/*	$OpenBSD: conflex.c,v 1.19 2017/04/24 14:58:36 krw Exp $	*/

/* Lexical scanner for dhcpd config file... */

/*
 * Copyright (c) 1995, 1996, 1997 The Internet Software Consortium.
 * 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.
 * 3. Neither the name of The Internet Software Consortium 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 INTERNET SOFTWARE CONSORTIUM 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 INTERNET SOFTWARE CONSORTIUM 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.
 *
 * This software has been written for the Internet Software Consortium
 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
 * Enterprises.  To learn more about the Internet Software Consortium,
 * see ``http://www.vix.com/isc''.  To learn more about Vixie
 * Enterprises, see ``http://www.vix.com''.
 */

#include <sys/types.h>
#include <sys/socket.h>

#include <net/if.h>

#include <netinet/in.h>

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "dhcp.h"
#include "tree.h"
#include "dhcpd.h"
#include "dhctoken.h"

int lexline;
int lexchar;
char *token_line;
char *prev_line;
char *cur_line;
char *tlname;
int eol_token;

static char line1[81];
static char line2[81];
static int lpos;
static int line;
static int tlpos;
static int tline;
static int token;
static int ugflag;
static char *tval;
static char tokbuf[1500];

static int get_char(FILE *);
static int get_token(FILE *);
static void skip_to_eol(FILE *);
static int read_string(FILE *);
static int read_num_or_name(int, FILE *);
static int intern(char *, int);
static int kw_cmp(const void *, const void *);

void
new_parse(char *name)
{
	tlname = name;
	lpos = line = 1;
	cur_line = line1;
	prev_line = line2;
	token_line = cur_line;
	cur_line[0] = prev_line[0] = 0;
	warnings_occurred = 0;
}

static int
get_char(FILE *cfile)
{
	int c = getc(cfile);
	if (!ugflag) {
		if (c == '\n') {
			if (cur_line == line1) {
				cur_line = line2;
				prev_line = line1;
			} else {
				cur_line = line1;
				prev_line = line2;
			}
			line++;
			lpos = 1;
			cur_line[0] = 0;
		} else if (c != EOF) {
			if (lpos < sizeof(line1)) {
				cur_line[lpos - 1] = c;
				cur_line[lpos] = 0;
			}
			lpos++;
		}
	} else
		ugflag = 0;
	return (c);
}

static int
get_token(FILE *cfile)
{
	int		c, ttok;
	static char	tb[2];
	int		l, p;

	do {
		l = line;
		p = lpos;

		c = get_char(cfile);

		if (!(c == '\n' && eol_token) && isascii(c) && isspace(c))
			continue;
		if (c == '#') {
			skip_to_eol(cfile);
			continue;
		}
		lexline = l;
		lexchar = p;
		if (c == '"') {
			ttok = read_string(cfile);
			break;
		} else if (c == '-' || (isascii(c) && isalnum(c))) {
			ttok = read_num_or_name(c, cfile);
			break;
		} else {
			tb[0] = c;
			tb[1] = 0;
			tval = tb;
			ttok = c;
			break;
		}
	} while (1);
	return (ttok);
}

int
next_token(char **rval, FILE *cfile)
{
	int	rv;

	if (token) {
		if (lexline != tline)
			token_line = cur_line;
		lexchar = tlpos;
		lexline = tline;
		rv = token;
		token = 0;
	} else {
		rv = get_token(cfile);
		token_line = cur_line;
	}
	if (rval)
		*rval = tval;

	return (rv);
}

int
peek_token(char **rval, FILE *cfile)
{
	int	x;

	if (!token) {
		tlpos = lexchar;
		tline = lexline;
		token = get_token(cfile);
		if (lexline != tline)
			token_line = prev_line;
		x = lexchar;
		lexchar = tlpos;
		tlpos = x;
		x = lexline;
		lexline = tline;
		tline = x;
	}
	if (rval)
		*rval = tval;

	return (token);
}

static void
skip_to_eol(FILE *cfile)
{
	int	c;

	do {
		c = get_char(cfile);
		if (c == EOF)
			return;
		if (c == '\n')
			return;
	} while (1);
}

static int
read_string(FILE *cfile)
{
	int i, c, bs;

	bs = i = 0;
	do {
		c = get_char(cfile);
		if (bs)
			bs = 0;
		else if (c == '\\')
			bs = 1;

		if (c != '"' && c != EOF && bs == 0)
			tokbuf[i++] = c;

	} while (i < (sizeof(tokbuf) - 1) && c != EOF && c != '"');

	if (c == EOF)
		parse_warn("eof in string constant");
	else if (c != '"')
		parse_warn("string constant larger than internal buffer");

	tokbuf[i] = 0;
	tval = tokbuf;

	return (TOK_STRING);
}

static int
read_num_or_name(int c, FILE *cfile)
{
	int i, rv, xdigits;

	xdigits = isxdigit(c) ? 1 : 0;

	tokbuf[0] = c;
	for (i = 1; i < sizeof(tokbuf); i++) {
		c = get_char(cfile);
		if (!isascii(c) || (c != '-' && c != '_' && !isalnum(c))) {
			ungetc(c, cfile);
			ugflag = 1;
			break;
		}
		if (isxdigit(c))
			xdigits++;
		tokbuf[i] = c;
	}
	if (i == sizeof(tokbuf)) {
		parse_warn("token larger than internal buffer");
		i--;
		c = tokbuf[i];
		if (isxdigit(c))
			xdigits--;
	}
	tokbuf[i] = 0;
	tval = tokbuf;

	c = (unsigned int)tokbuf[0];

	if (c == '-')
		rv = TOK_NUMBER;
	else
		rv = intern(tval, TOK_NUMBER_OR_NAME);

	if (rv == TOK_NUMBER_OR_NAME && xdigits != i)
		rv = TOK_NAME;

	return (rv);
}

static const struct keywords {
	const char	*k_name;
	int		k_val;
} keywords[] = {
	{ "abandoned",			TOK_ABANDONED },
	{ "allow",			TOK_ALLOW },
	{ "always-reply-rfc1048",	TOK_ALWAYS_REPLY_RFC1048 },
	{ "authoritative",		TOK_AUTHORITATIVE },
	{ "booting",			TOK_BOOTING },
	{ "bootp",			TOK_BOOTP },
	{ "class",			TOK_CLASS },
	{ "client-hostname",		TOK_CLIENT_HOSTNAME },
	{ "default-lease-time",		TOK_DEFAULT_LEASE_TIME },
	{ "deny",			TOK_DENY },
	{ "domain",			TOK_DOMAIN },
	{ "dynamic-bootp",		TOK_DYNAMIC_BOOTP },
	{ "dynamic-bootp-lease-cutoff",	TOK_DYNAMIC_BOOTP_LEASE_CUTOFF },
	{ "dynamic-bootp-lease-length",	TOK_DYNAMIC_BOOTP_LEASE_LENGTH },
	{ "echo-client-id",		TOK_ECHO_CLIENT_ID },
	{ "ends",			TOK_ENDS },
	{ "ethernet",			TOK_ETHERNET },
	{ "filename",			TOK_FILENAME },
	{ "fixed-address",		TOK_FIXED_ADDR },
	{ "get-lease-hostnames",	TOK_GET_LEASE_HOSTNAMES },
	{ "group",			TOK_GROUP },
	{ "hardware",			TOK_HARDWARE },
	{ "host",			TOK_HOST },
	{ "hostname",			TOK_HOSTNAME },
	{ "ipsec-tunnel",		TOK_IPSEC_TUNNEL },
	{ "lease",			TOK_LEASE },
	{ "max-lease-time",		TOK_MAX_LEASE_TIME },
	{ "netmask",			TOK_NETMASK },
	{ "next-server",		TOK_NEXT_SERVER },
	{ "not",			TOK_TOKEN_NOT },
	{ "option",			TOK_OPTION },
	{ "range",			TOK_RANGE },
	{ "server-identifier",		TOK_SERVER_IDENTIFIER },
	{ "server-name",		TOK_SERVER_NAME },
	{ "shared-network",		TOK_SHARED_NETWORK },
	{ "starts",			TOK_STARTS },
	{ "subnet",			TOK_SUBNET },
	{ "timeout",			TOK_TIMEOUT },
	{ "timestamp",			TOK_TIMESTAMP },
	{ "uid",			TOK_UID },
	{ "unknown-clients",		TOK_UNKNOWN_CLIENTS },
	{ "use-host-decl-names",	TOK_USE_HOST_DECL_NAMES },
	{ "use-lease-addr-for-default-route",
					TOK_USE_LEASE_ADDR_FOR_DEFAULT_ROUTE },
	{ "user-class",			TOK_USER_CLASS },
	{ "vendor-class",		TOK_VENDOR_CLASS }
};

static int
kw_cmp(const void *k, const void *e)
{
	return (strcasecmp(k, ((const struct keywords *)e)->k_name));
}

static int
intern(char *atom, int dfv)
{
	const struct keywords *p;

	p = bsearch(atom, keywords, sizeof(keywords)/sizeof(keywords[0]),
	    sizeof(keywords[0]), kw_cmp);
	if (p)
		return (p->k_val);
	return (dfv);
}