tree.c

DHCP服务器源码

/* tree.c

   Routines for manipulating parse trees... */

/*
 * 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: tree.c,v 1.101.2.9 2004/06/17 20:54:39 dhankins Exp $ Copyright (c) 2004 Internet Systems Consortium.  All rights reserved.\n";
#endif /* not lint */

#include "dhcpd.h"
#include <omapip/omapip_p.h>

struct binding_scope *global_scope;

static int do_host_lookup PROTO ((struct data_string *,
				  struct dns_host_entry *));

#ifdef NSUPDATE
struct __res_state resolver_state;
int resolver_inited = 0;
#endif

pair cons (car, cdr)
	caddr_t car;
	pair cdr;
{
	pair foo = (pair)dmalloc (sizeof *foo, MDL);
	if (!foo)
		log_fatal ("no memory for cons.");
	foo -> car = car;
	foo -> cdr = cdr;
	return foo;
}

int make_const_option_cache (oc, buffer, data, len, option, file, line)
	struct option_cache **oc;
	struct buffer **buffer;
	u_int8_t *data;
	unsigned len;
	struct option *option;
	const char *file;
	int line;
{
	struct buffer *bp;

	if (buffer) {
		bp = *buffer;
		*buffer = 0;
	} else {
		bp = (struct buffer *)0;
		if (!buffer_allocate (&bp, len, file, line)) {
			log_error ("%s(%d): can't allocate buffer.",
				   file, line);
			return 0;
		}
	}

	if (!option_cache_allocate (oc, file, line)) {
		log_error ("%s(%d): can't allocate option cache.", file, line);
		buffer_dereference (&bp, file, line);
		return 0;
	}

	(*oc) -> data.len = len;
	(*oc) -> data.buffer = bp;
	(*oc) -> data.data = &bp -> data [0];
	(*oc) -> data.terminated = 0;
	if (data)
		memcpy (&bp -> data [0], data, len);
	(*oc) -> option = option;
	return 1;
}

int make_host_lookup (expr, name)
	struct expression **expr;
	const char *name;
{
	if (!expression_allocate (expr, MDL)) {
		log_error ("No memory for host lookup tree node.");
		return 0;
	}
	(*expr) -> op = expr_host_lookup;
	if (!enter_dns_host (&((*expr) -> data.host_lookup), name)) {
		expression_dereference (expr, MDL);
		return 0;
	}
	return 1;
}

int enter_dns_host (dh, name)
	struct dns_host_entry **dh;
	const char *name;
{
	/* XXX This should really keep a hash table of hostnames
	   XXX and just add a new reference to a hostname that
	   XXX already exists, if possible, rather than creating
	   XXX a new structure. */
	if (!dns_host_entry_allocate (dh, name, MDL)) {
		log_error ("Can't allocate space for new host.");
		return 0;
	}
	return 1;
}

int make_const_data (struct expression **expr, const unsigned char *data,
		     unsigned len, int terminated, int allocate,
		     const char *file, int line)
{
	struct expression *nt;

	if (!expression_allocate (expr, file, line)) {
		log_error ("No memory for make_const_data tree node.");
		return 0;
	}
	nt = *expr;

	if (len) {
		if (allocate) {
			if (!buffer_allocate (&nt -> data.const_data.buffer,
					      len + terminated, file, line)) {
				log_error ("Can't allocate const_data buffer");
				expression_dereference (expr, file, line);
				return 0;
			}
			nt -> data.const_data.data =
				&nt -> data.const_data.buffer -> data [0];
			memcpy (nt -> data.const_data.buffer -> data,
				data, len + terminated);
		} else 
			nt -> data.const_data.data = data;
		nt -> data.const_data.terminated = terminated;
	} else
		nt -> data.const_data.data = 0;

	nt -> op = expr_const_data;
	nt -> data.const_data.len = len;
	return 1;
}

int make_const_int (expr, val)
	struct expression **expr;
	unsigned long val;
{
	if (!expression_allocate (expr, MDL)) {
		log_error ("No memory for make_const_int tree node.");
		return 0;
	}

	(*expr) -> op = expr_const_int;
	(*expr) -> data.const_int = val;
	return 1;
}

int make_concat (expr, left, right)
	struct expression **expr;
	struct expression *left, *right;
{
	/* If we're concatenating a null tree to a non-null tree, just
	   return the non-null tree; if both trees are null, return
	   a null tree. */
	if (!left) {
		if (!right)
			return 0;
		expression_reference (expr, right, MDL);
		return 1;
	}
	if (!right) {
		expression_reference (expr, left, MDL);
		return 1;
	}
			
	/* Otherwise, allocate a new node to concatenate the two. */
	if (!expression_allocate (expr, MDL)) {
		log_error ("No memory for concatenation expression node.");
		return 0;
	}
		
	(*expr) -> op = expr_concat;
	expression_reference (&(*expr) -> data.concat [0], left, MDL);
	expression_reference (&(*expr) -> data.concat [1], right, MDL);
	return 1;
}

int make_encapsulation (expr, name)
	struct expression **expr;
	struct data_string *name;
{
	/* Allocate a new node to store the encapsulation. */
	if (!expression_allocate (expr, MDL)) {
		log_error ("No memory for encapsulation expression node.");
		return 0;
	}
		
	(*expr) -> op = expr_encapsulate;
	data_string_copy (&(*expr) -> data.encapsulate, name, MDL);
	return 1;
}

int make_substring (new, expr, offset, length)
	struct expression **new;
	struct expression *expr;
	struct expression *offset;
	struct expression *length;
{
	/* Allocate an expression node to compute the substring. */
	if (!expression_allocate (new, MDL)) {
		log_error ("no memory for substring expression.");
		return 0;
	}
	(*new) -> op = expr_substring;
	expression_reference (&(*new) -> data.substring.expr, expr, MDL);
	expression_reference (&(*new) -> data.substring.offset, offset, MDL);
	expression_reference (&(*new) -> data.substring.len, length, MDL);
	return 1;
}

int make_limit (new, expr, limit)
	struct expression **new;
	struct expression *expr;
	int limit;
{
	struct expression *rv;

	/* Allocate a node to enforce a limit on evaluation. */
	if (!expression_allocate (new, MDL))
		log_error ("no memory for limit expression");
	(*new) -> op = expr_substring;
	expression_reference (&(*new) -> data.substring.expr, expr, MDL);

	/* Offset is a constant 0. */
	if (!expression_allocate (&(*new) -> data.substring.offset, MDL)) {
		log_error ("no memory for limit offset expression");
		expression_dereference (new, MDL);
		return 0;
	}
	(*new) -> data.substring.offset -> op = expr_const_int;
	(*new) -> data.substring.offset -> data.const_int = 0;

	/* Length is a constant: the specified limit. */
	if (!expression_allocate (&(*new) -> data.substring.len, MDL)) {
		log_error ("no memory for limit length expression");
		expression_dereference (new, MDL);
		return 0;
	}
	(*new) -> data.substring.len -> op = expr_const_int;
	(*new) -> data.substring.len -> data.const_int = limit;

	return 1;
}

int option_cache (struct option_cache **oc, struct data_string *dp,
		  struct expression *expr, struct option *option,
		  const char *file, int line)
{
	if (!option_cache_allocate (oc, file, line))
		return 0;
	if (dp)
		data_string_copy (&(*oc) -> data, dp, file, line);
	if (expr)
		expression_reference (&(*oc) -> expression, expr, file, line);
	(*oc) -> option = option;
	return 1;
}

int make_let (result, name)
	struct executable_statement **result;
	const char *name;
{
	if (!(executable_statement_allocate (result, MDL)))
		return 0;
	
	(*result) -> op = let_statement;
	(*result) -> data.let.name = dmalloc (strlen (name) + 1, MDL);
	if (!(*result) -> data.let.name) {
		executable_statement_dereference (result, MDL);
		return 0;
	}
	strcpy ((*result) -> data.let.name, name);
	return 1;
}
		
static int do_host_lookup (result, dns)
	struct data_string *result;
	struct dns_host_entry *dns;
{
	struct hostent *h;
	unsigned i, count;
	unsigned new_len;

#ifdef DEBUG_EVAL
	log_debug ("time: now = %d  dns = %d  diff = %d",
	       cur_time, dns -> timeout, cur_time - dns -> timeout);
#endif

	/* If the record hasn't timed out, just copy the data and return. */
	if (cur_time <= dns -> timeout) {
#ifdef DEBUG_EVAL
		log_debug ("easy copy: %d %s",
		       dns -> data.len,
		       (dns -> data.len > 4
			? inet_ntoa (*(struct in_addr *)(dns -> data.data))
			: 0));
#endif
		data_string_copy (result, &dns -> data, MDL);
		return 1;
	}
#ifdef DEBUG_EVAL
	log_debug ("Looking up %s", dns -> hostname);
#endif

	/* Otherwise, look it up... */
	h = gethostbyname (dns -> hostname);
	if (!h) {
#ifndef NO_H_ERRNO
		switch (h_errno) {
		      case HOST_NOT_FOUND:
#endif
			log_error ("%s: host unknown.", dns -> hostname);
#ifndef NO_H_ERRNO
			break;
		      case TRY_AGAIN:
			log_error ("%s: temporary name server failure",
				   dns -> hostname);
			break;
		      case NO_RECOVERY:
			log_error ("%s: name server failed", dns -> hostname);
			break;
		      case NO_DATA:
			log_error ("%s: no A record associated with address",
				   dns -> hostname);
		}
#endif /* !NO_H_ERRNO */

		/* Okay to try again after a minute. */
		dns -> timeout = cur_time + 60;
		data_string_forget (&dns -> data, MDL);
		return 0;
	}

#ifdef DEBUG_EVAL
	log_debug ("Lookup succeeded; first address is %s",
	       inet_ntoa (h -> h_addr_list [0]));
#endif

	/* Count the number of addresses we got... */
	for (count = 0; h -> h_addr_list [count]; count++)
		;
	
	/* Dereference the old data, if any. */
	data_string_forget (&dns -> data, MDL);

	/* Do we need to allocate more memory? */
	new_len = count * h -> h_length;
	if (!buffer_allocate (&dns -> data.buffer, new_len, MDL))
	{
		log_error ("No memory for %s.", dns -> hostname);
		return 0;
	}

	dns -> data.data = &dns -> data.buffer -> data [0];
	dns -> data.len = new_len;
	dns -> data.terminated = 0;

	/* Addresses are conveniently stored one to the buffer, so we
	   have to copy them out one at a time... :'( */
	for (i = 0; i < count; i++) {
		memcpy (&dns -> data.buffer -> data [h -> h_length * i],
			h -> h_addr_list [i], (unsigned)(h -> h_length));
	}
#ifdef DEBUG_EVAL
	log_debug ("dns -> data: %x  h -> h_addr_list [0]: %x",
		   *(int *)(dns -> buffer), h -> h_addr_list [0]);
#endif

	/* XXX Set the timeout for an hour from now.
	   XXX This should really use the time on the DNS reply. */
	dns -> timeout = cur_time + 3600;

#ifdef DEBUG_EVAL
	log_debug ("hard copy: %d %s", dns -> data.len,
	       (dns -> data.len > 4
		? inet_ntoa (*(struct in_addr *)(dns -> data.data)) : 0));
#endif
	data_string_copy (result, &dns -> data, MDL);
	return 1;
}

int evaluate_expression (result, packet, lease, client_state,
			 in_options, cfg_options, scope, expr, file, line)
	struct binding_value **result;
	struct packet *packet;
	struct lease *lease;
	struct client_state *client_state;
	struct option_state *in_options;
	struct option_state *cfg_options;
	struct binding_scope **scope;
	struct expression *expr;
	const char *file;
	int line;
{
	struct binding_value *bv;
	int status;
	struct binding *binding;

	bv = (struct binding_value *)0;

	if (expr -> op == expr_variable_reference) {
		if (!scope || !*scope)
			return 0;

		binding = find_binding (*scope, expr -> data.variable);

		if (binding && binding -> value) {
			if (result)
				binding_value_reference (result,
							 binding -> value,
							 file, line);
			return 1;
		} else
			return 0;
	} else if (expr -> op == expr_funcall) {
		struct string_list *s;
		struct expression *arg;
		struct binding_scope *ns;
		struct binding *nb;

		if (!scope || !*scope) {
			log_error ("%s: no such function.",
				   expr -> data.funcall.name);
			return 0;
		}

		binding = find_binding (*scope, expr -> data.funcall.name);

		if (!binding || !binding -> value) {
			log_error ("%s: no such function.",
				   expr -> data.funcall.name);
			return 0;
		}
		if (binding -> value -> type != binding_function) {
			log_error ("%s: not a function.",
				   expr -> data.funcall.name);
			return 0;
		}

		/* Create a new binding scope in which to define
		   the arguments to the function. */
		ns = (struct binding_scope *)0;
		if (!binding_scope_allocate (&ns, MDL)) {
			log_error ("%s: can't allocate argument scope.",
				   expr -> data.funcall.name);