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/* tree.c
Routines for manipulating parse trees... */
/*
* 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''.
*/
#ifndef lint
static char copyright[] =
"$Id: tree.c,v 1.10 1997/05/09 08:14:57 mellon Exp $ Copyright (c) 1995, 1996, 1997 The Internet Software Consortium. All rights reserved.\n";
#endif /* not lint */
#include "dhcpd.h"
static TIME tree_evaluate_recurse PROTO ((int *, unsigned char **, int *,
struct tree *));
static TIME do_host_lookup PROTO ((int *, unsigned char **, int *,
struct dns_host_entry *));
static void do_data_copy PROTO ((int *, unsigned char **, int *,
unsigned char *, int));
pair cons (car, cdr)
caddr_t car;
pair cdr;
{
pair foo = (pair)dmalloc (sizeof *foo, "cons");
if (!foo)
error ("no memory for cons.");
foo -> car = car;
foo -> cdr = cdr;
return foo;
}
struct tree_cache *tree_cache (tree)
struct tree *tree;
{
struct tree_cache *tc;
tc = new_tree_cache ("tree_cache");
if (!tc)
return 0;
tc -> value = (unsigned char *)0;
tc -> len = tc -> buf_size = 0;
tc -> timeout = 0;
tc -> tree = tree;
return tc;
}
struct tree *tree_host_lookup (name)
char *name;
{
struct tree *nt;
nt = new_tree ("tree_host_lookup");
if (!nt)
error ("No memory for host lookup tree node.");
nt -> op = TREE_HOST_LOOKUP;
nt -> data.host_lookup.host = enter_dns_host (name);
return nt;
}
struct dns_host_entry *enter_dns_host (name)
char *name;
{
struct dns_host_entry *dh;
if (!(dh = (struct dns_host_entry *)dmalloc
(sizeof (struct dns_host_entry), "enter_dns_host"))
|| !(dh -> hostname = dmalloc (strlen (name) + 1,
"enter_dns_host")))
error ("Can't allocate space for new host.");
strcpy (dh -> hostname, name);
dh -> data = (unsigned char *)0;
dh -> data_len = 0;
dh -> buf_len = 0;
dh -> timeout = 0;
return dh;
}
struct tree *tree_const (data, len)
unsigned char *data;
int len;
{
struct tree *nt;
if (!(nt = new_tree ("tree_const"))
|| !(nt -> data.const_val.data =
(unsigned char *)dmalloc (len, "tree_const")))
error ("No memory for constant data tree node.");
nt -> op = TREE_CONST;
memcpy (nt -> data.const_val.data, data, len);
nt -> data.const_val.len = len;
return nt;
}
struct tree *tree_concat (left, right)
struct tree *left, *right;
{
struct tree *nt;
/* 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)
return right;
if (!right)
return left;
/* If both trees are constant, combine them. */
if (left -> op == TREE_CONST && right -> op == TREE_CONST) {
unsigned char *buf = dmalloc (left -> data.const_val.len
+ right -> data.const_val.len,
"tree_concat");
if (!buf)
error ("No memory to concatenate constants.");
memcpy (buf, left -> data.const_val.data,
left -> data.const_val.len);
memcpy (buf + left -> data.const_val.len,
right -> data.const_val.data,
right -> data.const_val.len);
dfree (left -> data.const_val.data, "tree_concat");
dfree (right -> data.const_val.data, "tree_concat");
left -> data.const_val.data = buf;
left -> data.const_val.len += right -> data.const_val.len;
free_tree (right, "tree_concat");
return left;
}
/* Otherwise, allocate a new node to concatenate the two. */
if (!(nt = new_tree ("tree_concat")))
error ("No memory for data tree concatenation node.");
nt -> op = TREE_CONCAT;
nt -> data.concat.left = left;
nt -> data.concat.right = right;
return nt;
}
struct tree *tree_limit (tree, limit)
struct tree *tree;
int limit;
{
struct tree *rv;
/* If the tree we're limiting is constant, limit it now. */
if (tree -> op == TREE_CONST) {
if (tree -> data.const_val.len > limit)
tree -> data.const_val.len = limit;
return tree;
}
/* Otherwise, put in a node which enforces the limit on evaluation. */
rv = new_tree ("tree_limit");
if (!rv)
return (struct tree *)0;
rv -> op = TREE_LIMIT;
rv -> data.limit.tree = tree;
rv -> data.limit.limit = limit;
return rv;
}
int tree_evaluate (tree_cache)
struct tree_cache *tree_cache;
{
unsigned char *bp = tree_cache -> value;
int bc = tree_cache -> buf_size;
int bufix = 0;
/* If there's no tree associated with this cache, it evaluates
to a constant and that was detected at startup. */
if (!tree_cache -> tree)
return 1;
/* Try to evaluate the tree without allocating more memory... */
tree_cache -> timeout = tree_evaluate_recurse (&bufix, &bp, &bc,
tree_cache -> tree);
/* No additional allocation needed? */
if (bufix <= bc) {
tree_cache -> len = bufix;
return 1;
}
/* If we can't allocate more memory, return with what we
have (maybe nothing). */
if (!(bp = (unsigned char *)dmalloc (bufix, "tree_evaluate")))
return 0;
/* Record the change in conditions... */
bc = bufix;
bufix = 0;
/* Note that the size of the result shouldn't change on the
second call to tree_evaluate_recurse, since we haven't
changed the ``current'' time. */
tree_evaluate_recurse (&bufix, &bp, &bc, tree_cache -> tree);
/* Free the old buffer if needed, then store the new buffer
location and size and return. */
if (tree_cache -> value)
dfree (tree_cache -> value, "tree_evaluate");
tree_cache -> value = bp;
tree_cache -> len = bufix;
tree_cache -> buf_size = bc;
return 1;
}
static TIME tree_evaluate_recurse (bufix, bufp, bufcount, tree)
int *bufix;
unsigned char **bufp;
int *bufcount;
struct tree *tree;
{
int limit;
TIME t1, t2;
switch (tree -> op) {
case TREE_CONCAT:
t1 = tree_evaluate_recurse (bufix, bufp, bufcount,
tree -> data.concat.left);
t2 = tree_evaluate_recurse (bufix, bufp, bufcount,
tree -> data.concat.right);
if (t1 > t2)
return t2;
return t1;
case TREE_HOST_LOOKUP:
return do_host_lookup (bufix, bufp, bufcount,
tree -> data.host_lookup.host);
case TREE_CONST:
do_data_copy (bufix, bufp, bufcount,
tree -> data.const_val.data,
tree -> data.const_val.len);
t1 = MAX_TIME;
return t1;
case TREE_LIMIT:
limit = *bufix + tree -> data.limit.limit;
t1 = tree_evaluate_recurse (bufix, bufp, bufcount,
tree -> data.limit.tree);
*bufix = limit;
return t1;
default:
warn ("Bad node id in tree: %d.");
t1 = MAX_TIME;
return t1;
}
}
static TIME do_host_lookup (bufix, bufp, bufcount, dns)
int *bufix;
unsigned char **bufp;
int *bufcount;
struct dns_host_entry *dns;
{
struct hostent *h;
int i;
int new_len;
#ifdef DEBUG_EVAL
debug ("time: now = %d dns = %d %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
debug ("easy copy: %x %d %x",
dns -> data, dns -> data_len,
dns -> data ? *(int *)(dns -> data) : 0);
#endif
do_data_copy (bufix, bufp, bufcount,
dns -> data, dns -> data_len);
return dns -> timeout;
}
#ifdef DEBUG_EVAL
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
warn ("%s: host unknown.", dns -> hostname);
#ifndef NO_H_ERRNO
break;
case TRY_AGAIN:
warn ("%s: temporary name server failure",
dns -> hostname);
break;
case NO_RECOVERY:
warn ("%s: name server failed", dns -> hostname);
break;
case NO_DATA:
warn ("%s: no A record associated with address",
dns -> hostname);
}
#endif /* !NO_H_ERRNO */
/* Okay to try again after a minute. */
return cur_time + 60;
}
#ifdef DEBUG_EVAL
debug ("Lookup succeeded; first address is %x",
h -> h_addr_list [0]);
#endif
/* Count the number of addresses we got... */
for (i = 0; h -> h_addr_list [i]; i++)
;
/* Do we need to allocate more memory? */
new_len = i * h -> h_length;
if (dns -> buf_len < i) {
unsigned char *buf =
(unsigned char *)dmalloc (new_len, "do_host_lookup");
/* If we didn't get more memory, use what we have. */
if (!buf) {
new_len = dns -> buf_len;
if (!dns -> buf_len) {
dns -> timeout = cur_time + 60;
return dns -> timeout;
}
} else {
if (dns -> data)
dfree (dns -> data, "do_host_lookup");
dns -> data = buf;
dns -> buf_len = new_len;
}
}
/* Addresses are conveniently stored one to the buffer, so we
have to copy them out one at a time... :'( */
for (i = 0; i < new_len / h -> h_length; i++) {
memcpy (dns -> data + h -> h_length * i,
h -> h_addr_list [i], h -> h_length);
}
#ifdef DEBUG_EVAL
debug ("dns -> data: %x h -> h_addr_list [0]: %x",
*(int *)(dns -> data), h -> h_addr_list [0]);
#endif
dns -> data_len = new_len;
/* 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
debug ("hard copy: %x %d %x",
dns -> data, dns -> data_len, *(int *)(dns -> data));
#endif
do_data_copy (bufix, bufp, bufcount, dns -> data, dns -> data_len);
return dns -> timeout;
}
static void do_data_copy (bufix, bufp, bufcount, data, len)
int *bufix;
unsigned char **bufp;
int *bufcount;
unsigned char *data;
int len;
{
int space = *bufcount - *bufix;
/* If there's more space than we need, use only what we need. */
if (space > len)
space = len;
/* Copy as much data as will fit, then increment the buffer index
by the amount we actually had to copy, which could be more. */
if (space > 0)
memcpy (*bufp + *bufix, data, space);
*bufix += len;
}
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