/*	$OpenBSD: parse.c,v 1.73 2017/10/14 15:31:46 krw Exp $	*/

/* Common parser code for dhcpd and dhclient. */

/*
 * Copyright (c) 1995, 1996, 1997, 1998 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/queue.h>
#include <sys/socket.h>

#include <net/if.h>

#include <netinet/in.h>
#include <netinet/if_ether.h>

#include <errno.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <vis.h>

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

/*
 * Skip to the semicolon ending the current statement.   If we encounter
 * braces, the matching closing brace terminates the statement.   If we
 * encounter a right brace but haven't encountered a left brace, return
 * leaving the brace in the token buffer for the caller.   If we see a
 * semicolon and haven't seen a left brace, return.   This lets us skip
 * over:
 *
 *	statement;
 *	statement foo bar { }
 *	statement foo bar { statement { } }
 *	statement}
 *
 *	...et cetera.
 */
void
skip_to_semi(FILE *cfile)
{
	int		 token;
	int		 brace_count = 0;

	do {
		token = peek_token(NULL, cfile);
		if (token == '}') {
			if (brace_count > 0) {
				if (--brace_count == 0) {
					token = next_token(NULL, cfile);
					return;
				}
			} else
				return;
		} else if (token == '{') {
			brace_count++;
		} else if (token == ';' && brace_count == 0) {
			token = next_token(NULL, cfile);
			return;
		} else if (token == '\n') {
			/*
			 * EOL only happens when parsing
			 * /etc/resolv.conf, and we treat it like a
			 * semicolon because the resolv.conf file is
			 * line-oriented.
			 */
			token = next_token(NULL, cfile);
			return;
		}
		token = next_token(NULL, cfile);
	} while (token != EOF);
}

int
parse_semi(FILE *cfile)
{
	int token;

	token = next_token(NULL, cfile);
	if (token != ';') {
		parse_warn("expecting semicolon.");
		skip_to_semi(cfile);
		return 0;
	}
	return 1;
}

int
parse_string(FILE *cfile, unsigned int *len, char **string)
{
	static char	 unvisbuf[1500];
	char		*val;
	int		 i, token;

	token = next_token(&val, cfile);
	if (token == TOK_STRING) {
		i = strnunvis(unvisbuf, val, sizeof(unvisbuf));
		if (i >= 0) {
			*string = malloc(i+1);
			if (*string == NULL)
				fatal("unvis string %s", val);
			memcpy(*string, unvisbuf, i+1);	/* Copy the NUL. */
			if (len != NULL)
				*len = i;
			return 1;
		}
	}

	parse_warn("expecting string.");

	if (token != ';')
		skip_to_semi(cfile);

	return 0;
}

/*
 * cidr :== ip-address "/" bit-count
 * ip-address :== NUMBER [ DOT NUMBER [ DOT NUMBER [ DOT NUMBER ] ] ]
 * bit-count :== 0..32
 */
int
parse_cidr(FILE *cfile, unsigned char *cidr)
{
	uint8_t		 buf[5];
	const char	*errstr;
	char		*val;
	long long	 numval;
	unsigned int	 i;
	int		 token;

	memset(buf, 0, sizeof(buf));
	i = 1;	/* Last four octets hold subnet, first octet the # of bits. */
	do {
		token = next_token(&val, cfile);
		if (i == 0)
			numval = strtonum(val, 0, 32, &errstr);
		else
			numval = strtonum(val, 0, UINT8_MAX, &errstr);
		if (errstr != NULL)
			break;
		buf[i++] = numval;
		if (i == 1) {
			memcpy(cidr, buf, sizeof(buf)); /* XXX Need cidr_t */
			return 1;
		}
		token = next_token(NULL, cfile);
		if (token == '/')
			i = 0;
		if (i == sizeof(buf))
			break;
	} while (token == '.' || token == '/');

	parse_warn("expecting IPv4 CIDR block.");

	if (token != ';')
		skip_to_semi(cfile);

	return 0;
}

int
parse_ip_addr(FILE *cfile, struct in_addr *addr)
{
	struct in_addr	 buf;
	const char	*errstr;
	char		*val;
	long long	 numval;
	unsigned int	 i;
	int		 token;

	i = 0;
	do {
		token = next_token(&val, cfile);
		numval = strtonum(val, 0, UINT8_MAX, &errstr);
		if (errstr != NULL)
			break;
		((uint8_t *)&buf)[i++] = numval;
		if (i == sizeof(buf)) {
			memcpy(addr, &buf, sizeof(*addr));
			return 1;
		}
		token = next_token(NULL, cfile);
	} while (token == '.');

	parse_warn("expecting IPv4 address.");

	if (token != ';')
		skip_to_semi(cfile);

	return 0;
}

/*
 * lease-time :== NUMBER SEMI
 */
int
parse_lease_time(FILE *cfile, time_t *timep)
{
	const char	*errstr;
	char		*val;
	long long	 numval;
	int		 token;

	token = next_token(&val, cfile);
	numval = strtonum(val, 0, UINT32_MAX, &errstr);
	if (errstr == NULL) {
		*timep = numval;
		return 1;
	}

	parse_warn("expecting unsigned 32-bit decimal value.");
	if (token != ';')
		skip_to_semi(cfile);

	return 0;
}

int
parse_boolean(FILE *cfile, unsigned char *buf)
{
	char	*val;
	int	 token;

	token = next_token(&val, cfile);
	if (is_identifier(token) != 0) {
		if (strcasecmp(val, "true") == 0 ||
		    strcasecmp(val, "on") == 0) {
			buf[0] = 1;
			return 1;
		}
		if (strcasecmp(val, "false") == 0 ||
		    strcasecmp(val, "off") == 0) {
			buf[0] = 0;
			return 1;
		}
	}

	parse_warn("expecting boolean.");
	if (token != ';')
		skip_to_semi(cfile);

	return 0;
}

int
parse_decimal(FILE *cfile, unsigned char *buf, char fmt)
{
	const char	*errstr;
	char		*val, *msg;
	int		 bytes, rslt, token;
	long long	 numval, low, high;

	token = next_token(&val, cfile);

	switch (fmt) {
	case 'l':	/* Signed 32-bit integer. */
		low = INT32_MIN;
		high = INT32_MAX;
		bytes = 4;
		break;
	case 'L':	/* Unsigned 32-bit integer. */
		low = 0;
		high = UINT32_MAX;
		bytes = 4;
		break;
	case 'S':	/* Unsigned 16-bit integer. */
		low = 0;
		high = UINT16_MAX;
		bytes = 2;
		break;
	case 'B':	/* Unsigned 8-bit integer. */
		low = 0;
		high = UINT8_MAX;
		bytes = 1;
		break;
	default:
		return 0;
	}

	numval = strtonum(val, low, high, &errstr);
	if (errstr == NULL) {
		numval = htobe64(numval);
		memcpy(buf, (char *)&numval + (sizeof(numval) - bytes), bytes);
		return 1;
	}

	rslt = asprintf(&msg, "expecting integer between %lld and %lld", low,
	    high);
	if (rslt != -1) {
		parse_warn(msg);
		free(msg);
	}

	if (token != ';')
		skip_to_semi(cfile);

	return 0;
}

/*
 * date :== NUMBER NUMBER SLASH NUMBER SLASH NUMBER
 *		NUMBER COLON NUMBER COLON NUMBER UTC SEMI
 *
 * Dates are always in UTC; first number is day of week; next is
 * year/month/day; next is hours:minutes:seconds on a 24-hour
 * clock.
 *
 * XXX Will break after year 9999!
 */
int
parse_date(FILE *cfile, time_t *date)
{
	char		 timestr[23]; /* "wyyyy/mm/ddhh:mm:ssUTC" */
	struct tm	 tm;
	char		*val, *p;
	size_t		 n;
	time_t		 guess;
	int		 token;

	memset(timestr, 0, sizeof(timestr));

	n = 0;
	do {
		token = peek_token(&val, cfile);

		switch (token) {
		case EOF:
			n = sizeof(timestr);
			break;
		case';':
			/* strptime() ignores tm_isdt so ensure it is 0. */
			memset(&tm, 0, sizeof(tm));
			p = strptime(timestr, DB_TIMEFMT, &tm);
			if (p != NULL && *p == '\0') {
				guess = timegm(&tm);
				if (guess != -1) {
					*date = guess;
					return 1;
				}
			}
			token = next_token(NULL, cfile);
			break;
		default:
			n = strlcat(timestr, val, sizeof(timestr));
			token = next_token(NULL, cfile);
			break;

		}
	} while (n < sizeof(timestr) && token != ';');

	parse_warn("expecting UTC time.");

	if (token != ';')
		skip_to_semi(cfile);

	return 0;
}

void
parse_warn(char *msg)
{
	static char	 spaces[81];
	unsigned int	 i;

	log_warnx("%s: %s line %d: %s", log_procname, tlname, lexline, msg);
	log_warnx("%s: %s", log_procname, token_line);
	if ((unsigned int)lexchar < sizeof(spaces)) {
		memset(spaces, 0, sizeof(spaces));
		for (i = 0; (int)i < lexchar - 1; i++) {
			if (token_line[i] == '\t')
				spaces[i] = '\t';
			else
				spaces[i] = ' ';
		}
	}
	log_warnx("%s: %s^", log_procname, spaces);
}