xref: /openbsd-src/usr.sbin/dhcpd/parse.c (revision a15cd29622c9321173e85e78eff2317df5c665fe)

/*	$OpenBSD: parse.c,v 1.29 2024/06/27 16:39:31 florian Exp $	*/

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

#include <net/if.h>

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

#include <ctype.h>
#include <errno.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <unistd.h>

#include "dhcp.h"
#include "tree.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;
	char		*val;
	int		 brace_count = 0;

	do {
		token = peek_token(&val, cfile);
		if (token == '}') {
			if (brace_count) {
				token = next_token(&val, cfile);
				if (!--brace_count)
					return;
			} else
				return;
		} else if (token == '{') {
			brace_count++;
		} else if (token == ';' && !brace_count) {
			token = next_token(&val, 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(&val, cfile);
			return;
		}
		token = next_token(&val, cfile);
	} while (token != EOF);
}

int
parse_semi(FILE *cfile)
{
	int token;
	char *val;

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

/*
 * string-parameter :== STRING SEMI
 */
char *
parse_string(FILE *cfile)
{
	char *val, *s;
	int token;

	token = next_token(&val, cfile);
	if (token != TOK_STRING) {
		parse_warn("filename must be a string");
		skip_to_semi(cfile);
		return (NULL);
	}
	s = strdup(val);
	if (s == NULL)
		fatalx("no memory for string %s.", val);

	if (!parse_semi(cfile)) {
		free(s);
		return (NULL);
	}
	return (s);
}

/*
 * hostname :== identifier | hostname DOT identifier
 */
char *
parse_host_name(FILE *cfile)
{
	char *val, *s, *t;
	int token, len = 0;
	pair c = NULL;

	/* Read a dotted hostname... */
	do {
		/* Read a token, which should be an identifier. */
		token = next_token(&val, cfile);
		if (!is_identifier(token)) {
			parse_warn("expecting an identifier in hostname");
			skip_to_semi(cfile);
			return (NULL);
		}
		/* Store this identifier... */
		s = strdup(val);
		if (s == NULL)
			fatalx("can't allocate temp space for hostname.");
		c = cons((caddr_t) s, c);
		len += strlen(s) + 1;
		/*
		 * Look for a dot; if it's there, keep going, otherwise
		 * we're done.
		 */
		token = peek_token(&val, cfile);
		if (token == '.')
			token = next_token(&val, cfile);
	} while (token == '.');

	/* Assemble the hostname together into a string. */
	if (!(s = malloc(len)))
		fatalx("can't allocate space for hostname.");
	t = s + len;
	*--t = '\0';
	while (c) {
		pair cdr = c->cdr;
		int l = strlen((char *)c->car);

		t -= l;
		memcpy(t, (char *)c->car, l);
		/* Free up temp space. */
		free(c->car);
		free(c);
		c = cdr;
		if (t != s)
			*--t = '.';
	}
	return (s);
}

/*
 * hardware-parameter :== HARDWARE ETHERNET csns SEMI
 * csns :== NUMBER | csns COLON NUMBER
 */
void
parse_hardware_param(FILE *cfile, struct hardware *hardware)
{
	char *val;
	int token, hlen = 0;
	unsigned char *e, *t = NULL;

	token = next_token(&val, cfile);
	switch (token) {
	case TOK_ETHERNET:
		hardware->htype = HTYPE_ETHER;
		break;
	case TOK_IPSEC_TUNNEL:
		hardware->htype = HTYPE_IPSEC_TUNNEL;
		break;
	default:
		parse_warn("expecting a network hardware type");
		skip_to_semi(cfile);
		return;
	}


	/* Try looking up in /etc/ethers first. */
	if (hardware->htype == HTYPE_ETHER) {
		token = peek_token(&val, cfile);
		hlen = sizeof(struct ether_addr);
		if ((e = malloc(hlen)) == NULL)
			fatalx("can't allocate space for ethernet address.");
		if (ether_hostton(val, (struct ether_addr *)e) == 0) {
			(void)next_token(&val, cfile); /* consume token */
			t = e;
		} else
			free(e);
	}

	/*
	 * Parse the hardware address information.   Technically, it
	 * would make a lot of sense to restrict the length of the data
	 * we'll accept here to the length of a particular hardware
	 * address type.   Unfortunately, there are some broken clients
	 * out there that put bogus data in the chaddr buffer, and we
	 * accept that data in the lease file rather than simply failing
	 * on such clients.   Yuck.
	 */
	if (!t)
		t = parse_numeric_aggregate(cfile, NULL, &hlen, ':', 16, 8);

	if (!t)
		return;
	if (hlen > sizeof(hardware->haddr)) {
		free(t);
		parse_warn("hardware address too long");
	} else {
		hardware->hlen = hlen;
		memcpy((unsigned char *)&hardware->haddr[0], t,
		    hardware->hlen);
		if (hlen < sizeof(hardware->haddr))
			memset(&hardware->haddr[hlen], 0,
			    sizeof(hardware->haddr) - hlen);
		free(t);
	}

	token = next_token(&val, cfile);
	if (token != ';') {
		parse_warn("expecting semicolon.");
		skip_to_semi(cfile);
	}
}

/*
 * lease-time :== NUMBER SEMI
 */
void
parse_lease_time(FILE *cfile, time_t *timep)
{
	const char *errstr;
	char *val;
	uint32_t value;

	next_token(&val, cfile);

	value = strtonum(val, 0, UINT32_MAX, &errstr);
	if (errstr) {
		parse_warn("lease time is %s: %s", errstr, val);
		skip_to_semi(cfile);
		return;
	}

	*timep = value;

	parse_semi(cfile);
}

/*
 * No BNF for numeric aggregates - that's defined by the caller.  What
 * this function does is to parse a sequence of numbers separated by the
 * token specified in separator.  If max is zero, any number of numbers
 * will be parsed; otherwise, exactly max numbers are expected.  Base
 * and size tell us how to internalize the numbers once they've been
 * tokenized.
 */
unsigned char *
parse_numeric_aggregate(FILE *cfile, unsigned char *buf, int *max,
    int separator, int base, int size)
{
	char *val, *t;
	int token, count = 0;
	unsigned char *bufp = buf, *s = NULL;
	pair c = NULL;

	if (!bufp && *max) {
		bufp = malloc(*max * size / 8);
		if (!bufp)
			fatalx("can't allocate space for numeric aggregate");
	} else
		s = bufp;

	do {
		if (count) {
			token = peek_token(&val, cfile);
			if (token != separator) {
				if (!*max)
					break;
				if (token != '{' && token != '}')
					token = next_token(&val, cfile);
				parse_warn("too few numbers.");
				if (token != ';')
					skip_to_semi(cfile);
				return (NULL);
			}
			token = next_token(&val, cfile);
		}
		token = next_token(&val, cfile);

		if (token == EOF) {
			parse_warn("unexpected end of file");
			break;
		}
		if (token != TOK_NUMBER && token != TOK_NUMBER_OR_NAME) {
			parse_warn("expecting numeric value.");
			skip_to_semi(cfile);
			return (NULL);
		}
		/*
		 * If we can, convert the number now; otherwise, build a
		 * linked list of all the numbers.
		 */
		if (s) {
			convert_num(s, val, base, size);
			s += size / 8;
		} else {
			t = strdup(val);
			if (t == NULL)
				fatalx("no temp space for number.");
			c = cons(t, c);
		}
	} while (++count != *max);

	/* If we had to cons up a list, convert it now. */
	if (c) {
		bufp = malloc(count * size / 8);
		if (!bufp)
			fatalx("can't allocate space for numeric aggregate.");
		s = bufp + count - size / 8;
		*max = count;
	}
	while (c) {
		pair		cdr = c->cdr;
		convert_num(s, (char *)c->car, base, size);
		s -= size / 8;
		/* Free up temp space. */
		free(c->car);
		free(c);
		c = cdr;
	}
	return (bufp);
}

void
convert_num(unsigned char *buf, char *str, int base, int size)
{
	int negative = 0, tval, max;
	u_int32_t val = 0;
	char *ptr = str;

	if (*ptr == '-') {
		negative = 1;
		ptr++;
	}

	/* If base wasn't specified, figure it out from the data. */
	if (!base) {
		if (ptr[0] == '0') {
			if (ptr[1] == 'x') {
				base = 16;
				ptr += 2;
			} else if (isascii((unsigned char)ptr[1]) &&
			    isdigit((unsigned char)ptr[1])) {
				base = 8;
				ptr += 1;
			} else
				base = 10;
		} else
			base = 10;
	}

	do {
		tval = *ptr++;
		/* XXX assumes ASCII... */
		if (tval >= 'a')
			tval = tval - 'a' + 10;
		else if (tval >= 'A')
			tval = tval - 'A' + 10;
		else if (tval >= '0')
			tval -= '0';
		else {
			log_warnx("Bogus number: %s.", str);
			break;
		}
		if (tval >= base) {
			log_warnx("Bogus number: %s: digit %d not in base %d",
			    str, tval, base);
			break;
		}
		val = val * base + tval;
	} while (*ptr);

	if (negative)
		max = (1 << (size - 1));
	else
		max = (1 << (size - 1)) + ((1 << (size - 1)) - 1);
	if (val > max) {
		switch (base) {
		case 8:
			log_warnx("value %s%o exceeds max (%d) for precision.",
			    negative ? "-" : "", val, max);
			break;
		case 16:
			log_warnx("value %s%x exceeds max (%d) for precision.",
			    negative ? "-" : "", val, max);
			break;
		default:
			log_warnx("value %s%u exceeds max (%d) for precision.",
			    negative ? "-" : "", val, max);
			break;
		}
	}

	if (negative) {
		switch (size) {
		case 8:
			*buf = -(unsigned long)val;
			break;
		case 16:
			putShort(buf, -(unsigned long)val);
			break;
		case 32:
			putLong(buf, -(unsigned long)val);
			break;
		default:
			log_warnx("Unexpected integer size: %d", size);
			break;
		}
	} else {
		switch (size) {
		case 8:
			*buf = (u_int8_t)val;
			break;
		case 16:
			putUShort(buf, (u_int16_t)val);
			break;
		case 32:
			putULong(buf, val);
			break;
		default:
			log_warnx("Unexpected integer size: %d", size);
			break;
		}
	}
}

/*
 * 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.
 */
time_t
parse_date(FILE *cfile)
{
	struct tm tm;
	char timestr[26]; /* "w yyyy/mm/dd hh:mm:ss UTC" */
	char *val, *p;
	size_t n;
	time_t guess;
	int token;

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

	do {
		token = peek_token(NULL, cfile);
		switch (token) {
		case TOK_NAME:
		case TOK_NUMBER:
		case TOK_NUMBER_OR_NAME:
		case '/':
		case ':':
			token = next_token(&val, cfile);
			n = strlcat(timestr, val, sizeof(timestr));
			if (n >= sizeof(timestr)) {
				/* XXX Will break after year 9999! */
				parse_warn("time string too long");
				skip_to_semi(cfile);
				return (0);
			}
			break;
		case';':
			break;
		default:
			parse_warn("invalid time string");
			skip_to_semi(cfile);
			return (0);
		}
	} while (token != ';');

	parse_semi(cfile);

	memset(&tm, 0, sizeof(tm));	/* 'cuz strptime ignores tm_isdt. */
	p = strptime(timestr, DB_TIMEFMT, &tm);
	if (p == NULL || *p != '\0') {
		p = strptime(timestr, OLD_DB_TIMEFMT, &tm);
		if (p == NULL || *p != '\0') {
			parse_warn("unparseable time string");
			return (0);
		}
	}

	guess = timegm(&tm);
	if (guess == -1) {
		parse_warn("time could not be represented");
		return (0);
	}

	return (guess);
}

int warnings_occurred;

int
parse_warn(char *fmt, ...)
{
	static char fbuf[1024];
	static char mbuf[1024];
	static char spaces[81];
	va_list list;
	int i;

	snprintf(fbuf, sizeof(fbuf), "%s line %d: %s", tlname, lexline, mbuf);
	va_start(list, fmt);
	vsnprintf(mbuf, sizeof(mbuf), fbuf, list);
	va_end(list);

	log_warnx("%s", mbuf);
	log_warnx("%s", token_line);
	if (lexchar < sizeof(spaces)) {
		memset(spaces, 0, sizeof(spaces));
		for (i = 0; i < lexchar - 1; i++) {
			if (token_line[i] == '\t')
				spaces[i] = '\t';
			else
				spaces[i] = ' ';
		}
	}
	log_warnx("%s^", spaces);

	warnings_occurred = 1;

	return (0);
}