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freebsd/usr.sbin/nscd/parser.c
Stefan Eßer a397989d4e Add the possibility to specify a threshold for the number of negative cache
results required to have the cache return lookup failure.

A new configuration parameter is introduced, which must be set to a value
greater than 1 to activate this feature. The default behavior is unchanged.

The purpose of this change is to allow probes for the existence of an entry
(which are expected to fail), before that entry is added to one of the
queried databases, without the cache returning the stale information from
the probe query until that cache entry expires. If, for example, a new user
account is created after checking that the new account name is available,
the negative cache entry would prevent immediate access to the account.

For that example, the new configuration option

negative-confidence-threshold passwd 2

will require a second negative query result to consider the negative cache
entry for a passwd entry valid, but if the user account has been created
between the queries, then the positive query result from the second query
will be cached and returned.
2012-07-04 09:02:12 +00:00

523 lines
13 KiB
C

/*-
* Copyright (c) 2005 Michael Bushkov <bushman@rsu.ru>
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/time.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "config.h"
#include "debug.h"
#include "log.h"
#include "parser.h"
static void enable_cache(struct configuration *,const char *, int);
static struct configuration_entry *find_create_entry(struct configuration *,
const char *);
static int get_number(const char *, int, int);
static enum cache_policy_t get_policy(const char *);
static int get_yesno(const char *);
static int check_cachename(const char *);
static void check_files(struct configuration *, const char *, int);
static void set_keep_hot_count(struct configuration *, const char *, int);
static void set_negative_policy(struct configuration *, const char *,
enum cache_policy_t);
static void set_negative_time_to_live(struct configuration *,
const char *, int);
static void set_positive_policy(struct configuration *, const char *,
enum cache_policy_t);
static void set_perform_actual_lookups(struct configuration *, const char *,
int);
static void set_positive_time_to_live(struct configuration *,
const char *, int);
static void set_suggested_size(struct configuration *, const char *,
int size);
static void set_threads_num(struct configuration *, int);
static int strbreak(char *, char **, int);
static int
strbreak(char *str, char **fields, int fields_size)
{
char *c = str;
int i, num;
TRACE_IN(strbreak);
num = 0;
for (i = 0;
((*fields =
strsep(i < fields_size ? &c : NULL, "\n\t ")) != NULL);
++i)
if ((*(*fields)) != '\0') {
++fields;
++num;
}
TRACE_OUT(strbreak);
return (num);
}
/*
* Tries to find the configuration entry with the specified name. If search
* fails, the new entry with the default parameters will be created.
*/
static struct configuration_entry *
find_create_entry(struct configuration *config,
const char *entry_name)
{
struct configuration_entry *entry = NULL;
int res;
TRACE_IN(find_create_entry);
entry = configuration_find_entry(config, entry_name);
if (entry == NULL) {
entry = create_def_configuration_entry(entry_name);
assert( entry != NULL);
res = add_configuration_entry(config, entry);
assert(res == 0);
}
TRACE_OUT(find_create_entry);
return (entry);
}
/*
* The vast majority of the functions below corresponds to the particular
* keywords in the configuration file.
*/
static void
enable_cache(struct configuration *config, const char *entry_name, int flag)
{
struct configuration_entry *entry;
TRACE_IN(enable_cache);
entry = find_create_entry(config, entry_name);
entry->enabled = flag;
TRACE_OUT(enable_cache);
}
static void
set_positive_time_to_live(struct configuration *config,
const char *entry_name, int ttl)
{
struct configuration_entry *entry;
struct timeval lifetime;
TRACE_IN(set_positive_time_to_live);
assert(ttl >= 0);
assert(entry_name != NULL);
memset(&lifetime, 0, sizeof(struct timeval));
lifetime.tv_sec = ttl;
entry = find_create_entry(config, entry_name);
memcpy(&entry->positive_cache_params.max_lifetime,
&lifetime, sizeof(struct timeval));
memcpy(&entry->mp_cache_params.max_lifetime,
&lifetime, sizeof(struct timeval));
TRACE_OUT(set_positive_time_to_live);
}
static void
set_negative_time_to_live(struct configuration *config,
const char *entry_name, int nttl)
{
struct configuration_entry *entry;
struct timeval lifetime;
TRACE_IN(set_negative_time_to_live);
assert(nttl > 0);
assert(entry_name != NULL);
memset(&lifetime, 0, sizeof(struct timeval));
lifetime.tv_sec = nttl;
entry = find_create_entry(config, entry_name);
assert(entry != NULL);
memcpy(&entry->negative_cache_params.max_lifetime,
&lifetime, sizeof(struct timeval));
TRACE_OUT(set_negative_time_to_live);
}
static void
set_positive_confidence_threshold(struct configuration *config,
const char *entry_name, int conf_thresh)
{
struct configuration_entry *entry;
TRACE_IN(set_positive_conf_thresh);
assert(conf_thresh > 0);
assert(entry_name != NULL);
entry = find_create_entry(config, entry_name);
assert(entry != NULL);
entry->positive_cache_params.confidence_threshold = conf_thresh;
TRACE_OUT(set_positive_conf_thresh);
}
static void
set_negative_confidence_threshold(struct configuration *config,
const char *entry_name, int conf_thresh)
{
struct configuration_entry *entry;
TRACE_IN(set_negative_conf_thresh);
assert(conf_thresh > 0);
assert(entry_name != NULL);
entry = find_create_entry(config, entry_name);
assert(entry != NULL);
entry->negative_cache_params.confidence_threshold = conf_thresh;
TRACE_OUT(set_negative_conf_thresh);
}
/*
* Hot count is actually the elements size limit.
*/
static void
set_keep_hot_count(struct configuration *config,
const char *entry_name, int count)
{
struct configuration_entry *entry;
TRACE_IN(set_keep_hot_count);
assert(count >= 0);
assert(entry_name != NULL);
entry = find_create_entry(config, entry_name);
assert(entry != NULL);
entry->positive_cache_params.max_elemsize = count;
entry = find_create_entry(config, entry_name);
assert(entry != NULL);
entry->negative_cache_params.max_elemsize = count;
TRACE_OUT(set_keep_hot_count);
}
static void
set_positive_policy(struct configuration *config,
const char *entry_name, enum cache_policy_t policy)
{
struct configuration_entry *entry;
TRACE_IN(set_positive_policy);
assert(entry_name != NULL);
entry = find_create_entry(config, entry_name);
assert(entry != NULL);
entry->positive_cache_params.policy = policy;
TRACE_OUT(set_positive_policy);
}
static void
set_negative_policy(struct configuration *config,
const char *entry_name, enum cache_policy_t policy)
{
struct configuration_entry *entry;
TRACE_IN(set_negative_policy);
assert(entry_name != NULL);
entry = find_create_entry(config, entry_name);
assert(entry != NULL);
entry->negative_cache_params.policy = policy;
TRACE_OUT(set_negative_policy);
}
static void
set_perform_actual_lookups(struct configuration *config,
const char *entry_name, int flag)
{
struct configuration_entry *entry;
TRACE_IN(set_perform_actual_lookups);
assert(entry_name != NULL);
entry = find_create_entry(config, entry_name);
assert(entry != NULL);
entry->perform_actual_lookups = flag;
TRACE_OUT(set_perform_actual_lookups);
}
static void
set_suggested_size(struct configuration *config,
const char *entry_name, int size)
{
struct configuration_entry *entry;
TRACE_IN(set_suggested_size);
assert(config != NULL);
assert(entry_name != NULL);
assert(size > 0);
entry = find_create_entry(config, entry_name);
assert(entry != NULL);
entry->positive_cache_params.cache_entries_size = size;
entry->negative_cache_params.cache_entries_size = size;
TRACE_OUT(set_suggested_size);
}
static void
check_files(struct configuration *config, const char *entry_name, int flag)
{
TRACE_IN(check_files);
assert(entry_name != NULL);
TRACE_OUT(check_files);
}
static int
get_yesno(const char *str)
{
if (strcmp(str, "yes") == 0)
return (1);
else if (strcmp(str, "no") == 0)
return (0);
else
return (-1);
}
static int
get_number(const char *str, int low, int max)
{
char *end = NULL;
int res = 0;
if (str[0] == '\0')
return (-1);
res = strtol(str, &end, 10);
if (*end != '\0')
return (-1);
else
if (((res >= low) || (low == -1)) &&
((res <= max) || (max == -1)))
return (res);
else
return (-2);
}
static enum cache_policy_t
get_policy(const char *str)
{
if (strcmp(str, "fifo") == 0)
return (CPT_FIFO);
else if (strcmp(str, "lru") == 0)
return (CPT_LRU);
else if (strcmp(str, "lfu") == 0)
return (CPT_LFU);
return (-1);
}
static int
check_cachename(const char *str)
{
assert(str != NULL);
return ((strlen(str) > 0) ? 0 : -1);
}
static void
set_threads_num(struct configuration *config, int value)
{
assert(config != NULL);
config->threads_num = value;
}
/*
* The main configuration routine. Its implementation is hugely inspired by the
* the same routine implementation in Solaris NSCD.
*/
int
parse_config_file(struct configuration *config,
const char *fname, char const **error_str, int *error_line)
{
FILE *fin;
char buffer[255];
char *fields[128];
int field_count, line_num, value;
int res;
TRACE_IN(parse_config_file);
assert(config != NULL);
assert(fname != NULL);
fin = fopen(fname, "r");
if (fin == NULL) {
TRACE_OUT(parse_config_file);
return (-1);
}
res = 0;
line_num = 0;
memset(buffer, 0, sizeof(buffer));
while ((res == 0) && (fgets(buffer, sizeof(buffer) - 1, fin) != NULL)) {
field_count = strbreak(buffer, fields, sizeof(fields));
++line_num;
if (field_count == 0)
continue;
switch (fields[0][0]) {
case '#':
case '\0':
continue;
case 'e':
if ((field_count == 3) &&
(strcmp(fields[0], "enable-cache") == 0) &&
(check_cachename(fields[1]) == 0) &&
((value = get_yesno(fields[2])) != -1)) {
enable_cache(config, fields[1], value);
continue;
}
break;
case 'd':
if ((field_count == 2) &&
(strcmp(fields[0], "debug-level") == 0) &&
((value = get_number(fields[1], 0, 10)) != -1)) {
continue;
}
break;
case 'p':
if ((field_count == 3) &&
(strcmp(fields[0], "positive-time-to-live") == 0) &&
(check_cachename(fields[1]) == 0) &&
((value = get_number(fields[2], 0, -1)) != -1)) {
set_positive_time_to_live(config,
fields[1], value);
continue;
} else if ((field_count == 3) &&
(strcmp(fields[0], "positive-confidence-threshold") == 0) &&
((value = get_number(fields[2], 1, -1)) != -1)) {
set_positive_confidence_threshold(config,
fields[1], value);
continue;
} else if ((field_count == 3) &&
(strcmp(fields[0], "positive-policy") == 0) &&
(check_cachename(fields[1]) == 0) &&
((value = get_policy(fields[2])) != -1)) {
set_positive_policy(config, fields[1], value);
continue;
} else if ((field_count == 3) &&
(strcmp(fields[0], "perform-actual-lookups") == 0) &&
(check_cachename(fields[1]) == 0) &&
((value = get_yesno(fields[2])) != -1)) {
set_perform_actual_lookups(config, fields[1],
value);
continue;
}
break;
case 'n':
if ((field_count == 3) &&
(strcmp(fields[0], "negative-time-to-live") == 0) &&
(check_cachename(fields[1]) == 0) &&
((value = get_number(fields[2], 0, -1)) != -1)) {
set_negative_time_to_live(config,
fields[1], value);
continue;
} else if ((field_count == 3) &&
(strcmp(fields[0], "negative-confidence-threshold") == 0) &&
((value = get_number(fields[2], 1, -1)) != -1)) {
set_negative_confidence_threshold(config,
fields[1], value);
continue;
} else if ((field_count == 3) &&
(strcmp(fields[0], "negative-policy") == 0) &&
(check_cachename(fields[1]) == 0) &&
((value = get_policy(fields[2])) != -1)) {
set_negative_policy(config,
fields[1], value);
continue;
}
break;
case 's':
if ((field_count == 3) &&
(strcmp(fields[0], "suggested-size") == 0) &&
(check_cachename(fields[1]) == 0) &&
((value = get_number(fields[2], 1, -1)) != -1)) {
set_suggested_size(config, fields[1], value);
continue;
}
break;
case 't':
if ((field_count == 2) &&
(strcmp(fields[0], "threads") == 0) &&
((value = get_number(fields[1], 1, -1)) != -1)) {
set_threads_num(config, value);
continue;
}
break;
case 'k':
if ((field_count == 3) &&
(strcmp(fields[0], "keep-hot-count") == 0) &&
(check_cachename(fields[1]) == 0) &&
((value = get_number(fields[2], 0, -1)) != -1)) {
set_keep_hot_count(config,
fields[1], value);
continue;
}
break;
case 'c':
if ((field_count == 3) &&
(strcmp(fields[0], "check-files") == 0) &&
(check_cachename(fields[1]) == 0) &&
((value = get_yesno(fields[2])) != -1)) {
check_files(config,
fields[1], value);
continue;
}
break;
default:
break;
}
LOG_ERR_2("config file parser", "error in file "
"%s on line %d", fname, line_num);
*error_str = "syntax error";
*error_line = line_num;
res = -1;
}
fclose(fin);
TRACE_OUT(parse_config_file);
return (res);
}