parse.c

DHCP服务器源码

/* parse.c

   Common parser code for dhcpd and dhclient. */

/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1995-2003 by Internet Software Consortium
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 *   Internet Systems Consortium, Inc.
 *   950 Charter Street
 *   Redwood City, CA 94063
 *   <[e-mail]>
 *   http://www.isc.org/
 *
 * This software has been written for Internet Systems Consortium
 * by Ted Lemon in cooperation with Vixie Enterprises and Nominum, Inc.
 * To learn more about Internet Systems Consortium, see
 * ``http://www.isc.org/''.  To learn more about Vixie Enterprises,
 * see ``http://www.vix.com''.   To learn more about Nominum, Inc., see
 * ``http://www.nominum.com''.
 */

#ifndef lint
static char copyright[] =
"$Id: parse.c,v 1.104.2.17 2004/06/17 20:54:38 dhankins Exp $ Copyright (c) 2004 Internet Systems Consortium.  All rights reserved.\n";
#endif /* not lint */

#include "dhcpd.h"

/* Enumerations can be specified in option formats, and are used for
   parsing, so we define the routines that manage them here. */

struct enumeration *enumerations;

void add_enumeration (struct enumeration *enumeration)
{
	enumeration -> next = enumerations;
	enumerations = enumeration;
}

struct enumeration *find_enumeration (const char *name, int length)
{
	struct enumeration *e;

	for (e = enumerations; e; e = e -> next)
		if (strlen (e -> name) == length &&
		    !memcmp (e -> name, name, (unsigned)length))
			return e;
	return (struct enumeration *)0;
}

struct enumeration_value *find_enumeration_value (const char *name,
						  int length,
						  const char *value)
{
	struct enumeration *e;
	int i;

	e = find_enumeration (name, length);
	if (e) {
		for (i = 0; e -> values [i].name; i++) {
			if (!strcmp (value, e -> values [i].name))
				return &e -> values [i];
		}
	}
	return (struct enumeration_value *)0;
}

/* 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 (cfile)
	struct parse *cfile;
{
	skip_to_rbrace (cfile, 0);
}

void skip_to_rbrace (cfile, brace_count)
	struct parse *cfile;
	int brace_count;
{
	enum dhcp_token token;
	const char *val;

#if defined (DEBUG_TOKEN)
	log_error ("skip_to_rbrace: %d\n", brace_count);
#endif
	do {
		token = peek_token (&val, (unsigned *)0, cfile);
		if (token == RBRACE) {
			token = next_token (&val, (unsigned *)0, cfile);
			if (brace_count) {
				if (!--brace_count)
					return;
			} else
				return;
		} else if (token == LBRACE) {
			brace_count++;
		} else if (token == SEMI && !brace_count) {
			token = next_token (&val, (unsigned *)0, cfile);
			return;
		} else if (token == EOL) {
			/* 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, (unsigned *)0, cfile);
			return;
		}
		token = next_token (&val, (unsigned *)0, cfile);
	} while (token != END_OF_FILE);
}

int parse_semi (cfile)
	struct parse *cfile;
{
	enum dhcp_token token;
	const char *val;

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

/* string-parameter :== STRING SEMI */

int parse_string (cfile, sptr, lptr)
	struct parse *cfile;
	char **sptr;
	unsigned *lptr;
{
	const char *val;
	enum dhcp_token token;
	char *s;
	unsigned len;

	token = next_token (&val, &len, cfile);
	if (token != STRING) {
		parse_warn (cfile, "expecting a string");
		skip_to_semi (cfile);
		return 0;
	}
	s = (char *)dmalloc (len + 1, MDL);
	if (!s)
		log_fatal ("no memory for string %s.", val);
	memcpy (s, val, len + 1);

	if (!parse_semi (cfile)) {
		dfree (s, MDL);
		return 0;
	}
	if (sptr)
		*sptr = s;
	else
		dfree (s, MDL);
	if (lptr)
		*lptr = len;
	return 1;
}

/*
 * hostname :== IDENTIFIER
 *		| IDENTIFIER DOT
 *		| hostname DOT IDENTIFIER
 */

char *parse_host_name (cfile)
	struct parse *cfile;
{
	const char *val;
	enum dhcp_token token;
	unsigned len = 0;
	char *s;
	char *t;
	pair c = (pair)0;
	int ltid = 0;
	
	/* Read a dotted hostname... */
	do {
		/* Read a token, which should be an identifier. */
		token = peek_token (&val, (unsigned *)0, cfile);
		if (!is_identifier (token) && token != NUMBER)
			break;
		token = next_token (&val, (unsigned *)0, cfile);

		/* Store this identifier... */
		if (!(s = (char *)dmalloc (strlen (val) + 1, MDL)))
			log_fatal ("can't allocate temp space for hostname.");
		strcpy (s, val);
		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, (unsigned *)0, cfile);
		if (token == DOT) {
			token = next_token (&val, (unsigned *)0, cfile);
			ltid = 1;
		} else
			ltid = 0;
	} while (token == DOT);

	/* Should be at least one token. */
	if (!len)
		return (char *)0;

	/* Assemble the hostname together into a string. */
	if (!(s = (char *)dmalloc (len + ltid, MDL)))
		log_fatal ("can't allocate space for hostname.");
	t = s + len + ltid;
	*--t = 0;
	if (ltid)
		*--t = '.';
	while (c) {
		pair cdr = c -> cdr;
		unsigned l = strlen ((char *)(c -> car));
		t -= l;
		memcpy (t, (char *)(c -> car), l);
		/* Free up temp space. */
		dfree (c -> car, MDL);
		dfree (c, MDL);
		c = cdr;
		if (t != s)
			*--t = '.';
	}
	return s;
}

/* ip-addr-or-hostname :== ip-address | hostname
   ip-address :== NUMBER DOT NUMBER DOT NUMBER DOT NUMBER
   
   Parse an ip address or a hostname.   If uniform is zero, put in
   an expr_substring node to limit hostnames that evaluate to more
   than one IP address. */

int parse_ip_addr_or_hostname (expr, cfile, uniform)
	struct expression **expr;
	struct parse *cfile;
	int uniform;
{
	const char *val;
	enum dhcp_token token;
	unsigned char addr [4];
	unsigned len = sizeof addr;
	char *name;
	struct expression *x = (struct expression *)0;

	token = peek_token (&val, (unsigned *)0, cfile);
	if (is_identifier (token)) {
		name = parse_host_name (cfile);
		if (!name)
			return 0;
		if (!make_host_lookup (expr, name)) {
			dfree(name, MDL);
			return 0;
		}
		dfree(name, MDL);
		if (!uniform) {
			if (!make_limit (&x, *expr, 4))
				return 0;
			expression_dereference (expr, MDL);
			*expr = x;
		}
	} else if (token == NUMBER) {
		if (!parse_numeric_aggregate (cfile, addr, &len, DOT, 10, 8))
			return 0;
		return make_const_data (expr, addr, len, 0, 1, MDL);
	} else {
		if (token != RBRACE && token != LBRACE)
			token = next_token (&val, (unsigned *)0, cfile);
		parse_warn (cfile, "%s (%d): expecting IP address or hostname",
			    val, token);
		if (token != SEMI)
			skip_to_semi (cfile);
		return 0;
	}

	return 1;
}	
	
/*
 * ip-address :== NUMBER DOT NUMBER DOT NUMBER DOT NUMBER
 */

int parse_ip_addr (cfile, addr)
	struct parse *cfile;
	struct iaddr *addr;
{
	const char *val;
	enum dhcp_token token;

	addr -> len = 4;
	if (parse_numeric_aggregate (cfile, addr -> iabuf,
				     &addr -> len, DOT, 10, 8))
		return 1;
	return 0;
}	

/*
 * hardware-parameter :== HARDWARE hardware-type colon-seperated-hex-list SEMI
 * hardware-type :== ETHERNET | TOKEN_RING | FDDI
 */

void parse_hardware_param (cfile, hardware)
	struct parse *cfile;
	struct hardware *hardware;
{
	const char *val;
	enum dhcp_token token;
	unsigned hlen;
	unsigned char *t;

	token = next_token (&val, (unsigned *)0, cfile);
	switch (token) {
	      case ETHERNET:
		hardware -> hbuf [0] = HTYPE_ETHER;
		break;
	      case TOKEN_RING:
		hardware -> hbuf [0] = HTYPE_IEEE802;
		break;
	      case FDDI:
		hardware -> hbuf [0] = HTYPE_FDDI;
		break;
	      default:
		if (!strncmp (val, "unknown-", 8)) {
			hardware -> hbuf [0] = atoi (&val [8]);
		} else {
			parse_warn (cfile,
				    "expecting a network hardware type");
			skip_to_semi (cfile);

			return;
		}
	}

	/* 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. */
	hlen = 0;
	token = peek_token (&val, (unsigned *)0, cfile);
	if (token == SEMI) {
		hardware -> hlen = 1;
		goto out;
	}
	t = parse_numeric_aggregate (cfile, (unsigned char *)0, &hlen,
				     COLON, 16, 8);
	if (!t) {
		hardware -> hlen = 1;
		return;
	}
	if (hlen + 1 > sizeof hardware -> hbuf) {
		dfree (t, MDL);
		parse_warn (cfile, "hardware address too long");
	} else {
		hardware -> hlen = hlen + 1;
		memcpy ((unsigned char *)&hardware -> hbuf [1], t, hlen);
		if (hlen + 1 < sizeof hardware -> hbuf)
			memset (&hardware -> hbuf [hlen + 1], 0,
				(sizeof hardware -> hbuf) - hlen - 1);
		dfree (t, MDL);
	}
	
      out:
	token = next_token (&val, (unsigned *)0, cfile);
	if (token != SEMI) {
		parse_warn (cfile, "expecting semicolon.");
		skip_to_semi (cfile);
	}
}

/* lease-time :== NUMBER SEMI */

void parse_lease_time (cfile, timep)
	struct parse *cfile;
	TIME *timep;
{
	const char *val;
	enum dhcp_token token;

	token = next_token (&val, (unsigned *)0, cfile);
	if (token != NUMBER) {
		parse_warn (cfile, "Expecting numeric lease time");
		skip_to_semi (cfile);
		return;
	}
	convert_num (cfile, (unsigned char *)timep, val, 10, 32);
	/* Unswap the number - convert_num returns stuff in NBO. */
	*timep = ntohl (*timep); /* XXX */

	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 seperated by
   the token specified in seperator.  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 (cfile, buf,
					max, seperator, base, size)
	struct parse *cfile;
	unsigned char *buf;
	unsigned *max;
	int seperator;
	int base;
	unsigned size;
{
	const char *val;
	enum dhcp_token token;
	unsigned char *bufp = buf, *s, *t;
	unsigned count = 0;
	pair c = (pair)0;

	if (!bufp && *max) {
		bufp = (unsigned char *)dmalloc (*max * size / 8, MDL);
		if (!bufp)
			log_fatal ("no space for numeric aggregate");
		s = 0;
	} else
		s = bufp;

	do {
		if (count) {
			token = peek_token (&val, (unsigned *)0, cfile);
			if (token != seperator) {
				if (!*max)
					break;
				if (token != RBRACE && token != LBRACE)
					token = next_token (&val,
							    (unsigned *)0,
							    cfile);
				parse_warn (cfile, "too few numbers.");
				if (token != SEMI)
					skip_to_semi (cfile);
				return (unsigned char *)0;
			}
			token = next_token (&val, (unsigned *)0, cfile);
		}
		token = next_token (&val, (unsigned *)0, cfile);

		if (token == END_OF_FILE) {
			parse_warn (cfile, "unexpected end of file");
			break;
		}

		/* Allow NUMBER_OR_NAME if base is 16. */
		if (token != NUMBER &&
		    (base != 16 || token != NUMBER_OR_NAME)) {
			parse_warn (cfile, "expecting numeric value.");
			skip_to_semi (cfile);
			return (unsigned char *)0;
		}
		/* If we can, convert the number now; otherwise, build
		   a linked list of all the numbers. */
		if (s) {
			convert_num (cfile, s, val, base, size);
			s += size / 8;
		} else {
			t = (unsigned char *)dmalloc (strlen (val) + 1, MDL);
			if (!t)
				log_fatal ("no temp space for number.");
			strcpy ((char *)t, val);
			c = cons ((caddr_t)t, c);
		}
	} while (++count != *max);

	/* If we had to cons up a list, convert it now. */
	if (c) {
		bufp = (unsigned char *)dmalloc (count * size / 8, MDL);
		if (!bufp)
			log_fatal ("no space for numeric aggregate.");
		s = bufp + count - size / 8;
		*max = count;
	}
	while (c) {
		pair cdr = c -> cdr;
		convert_num (cfile, s, (char *)(c -> car), base, size);
		s -= size / 8;
		/* Free up temp space. */
		dfree (c -> car, MDL);
		dfree (c, MDL);
		c = cdr;
	}
	return bufp;
}

void convert_num (cfile, buf, str, base, size)
	struct parse *cfile;
	unsigned char *buf;
	const char *str;
	int base;
	unsigned size;
{