464cdbbb6e
This simplifies the code and allows older records to be reused when no more memory can be allocated for new addresses. Each slot of the hash table has 16 records and there is no chaining between different slots. Reused records may be newer than records in other slots, but the search time remains constant.
280 lines
6.7 KiB
C
280 lines
6.7 KiB
C
/*
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chronyd/chronyc - Programs for keeping computer clocks accurate.
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**********************************************************************
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* Copyright (C) Richard P. Curnow 1997-2003
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* Copyright (C) Miroslav Lichvar 2009
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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**********************************************************************
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=======================================================================
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This module keeps a count of the number of successful accesses by
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clients, and the times of the last accesses.
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This can be used for status reporting, and (in the case of a
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server), if it needs to know which clients have made use of its data
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recently.
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*/
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#include "config.h"
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#include "sysincl.h"
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#include "array.h"
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#include "clientlog.h"
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#include "conf.h"
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#include "memory.h"
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#include "reports.h"
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#include "util.h"
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#include "logging.h"
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typedef struct {
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IPAddr ip_addr;
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uint32_t ntp_hits;
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uint32_t cmd_hits;
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time_t last_ntp_hit;
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time_t last_cmd_hit;
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} Record;
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/* Hash table of records, there is a fixed number of records per slot */
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static ARR_Instance records;
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#define SLOT_BITS 4
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/* Number of records in one slot of the hash table */
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#define SLOT_SIZE (1U << SLOT_BITS)
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/* Minimum number of slots */
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#define MIN_SLOTS 1
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/* Maximum number of slots, this is a hard limit */
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#define MAX_SLOTS (1U << (24 - SLOT_BITS))
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/* Number of slots in the hash table */
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static unsigned int slots;
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/* Maximum number of slots given memory allocation limit */
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static unsigned int max_slots;
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/* Flag indicating whether facility is turned on or not */
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static int active;
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/* ================================================== */
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static int expand_hashtable(void);
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/* ================================================== */
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static Record *
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get_record(IPAddr *ip)
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{
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unsigned int first, i;
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time_t last_hit, oldest_hit = 0;
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Record *record, *oldest_record;
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if (ip->family != IPADDR_INET4 && ip->family != IPADDR_INET6)
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return NULL;
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while (1) {
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/* Get index of the first record in the slot */
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first = UTI_IPToHash(ip) % slots * SLOT_SIZE;
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for (i = 0, oldest_record = NULL; i < SLOT_SIZE; i++) {
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record = ARR_GetElement(records, first + i);
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if (!UTI_CompareIPs(ip, &record->ip_addr, NULL))
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return record;
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if (record->ip_addr.family == IPADDR_UNSPEC)
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break;
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last_hit = MAX(record->last_ntp_hit, record->last_cmd_hit);
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if (!oldest_record ||
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oldest_hit > last_hit ||
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(oldest_hit == last_hit && record->ntp_hits + record->cmd_hits <
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oldest_record->ntp_hits + oldest_record->cmd_hits)) {
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oldest_record = record;
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oldest_hit = last_hit;
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}
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}
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/* If the slot still has an empty record, use it */
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if (record->ip_addr.family == IPADDR_UNSPEC)
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break;
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/* Resize the table if possible and try again as the new slot may
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have some empty records */
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if (expand_hashtable())
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continue;
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/* There is no other option, replace the oldest record */
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record = oldest_record;
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break;
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}
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record->ip_addr = *ip;
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record->ntp_hits = record->cmd_hits = 0;
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record->last_ntp_hit = record->last_cmd_hit = 0;
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return record;
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}
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/* ================================================== */
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static int
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expand_hashtable(void)
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{
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ARR_Instance old_records;
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Record *old_record, *new_record;
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unsigned int i;
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old_records = records;
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if (2 * slots > max_slots)
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return 0;
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records = ARR_CreateInstance(sizeof (Record));
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slots = MAX(MIN_SLOTS, 2 * slots);
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assert(slots <= max_slots);
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ARR_SetSize(records, slots * SLOT_SIZE);
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/* Mark all new records as empty */
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for (i = 0; i < slots * SLOT_SIZE; i++) {
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new_record = ARR_GetElement(records, i);
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new_record->ip_addr.family = IPADDR_UNSPEC;
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}
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if (!old_records)
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return 1;
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/* Copy old records to the new hash table */
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for (i = 0; i < ARR_GetSize(old_records); i++) {
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old_record = ARR_GetElement(old_records, i);
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if (old_record->ip_addr.family == IPADDR_UNSPEC)
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continue;
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new_record = get_record(&old_record->ip_addr);
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assert(new_record);
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*new_record = *old_record;
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}
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ARR_DestroyInstance(old_records);
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return 1;
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}
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/* ================================================== */
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void
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CLG_Initialise(void)
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{
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active = !CNF_GetNoClientLog();
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if (!active)
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return;
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/* Calculate the maximum number of slots that can be allocated in the
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configured memory limit. Take into account expanding of the hash
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table where two copies exist at the same time. */
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max_slots = CNF_GetClientLogLimit() / (sizeof (Record) * SLOT_SIZE * 3 / 2);
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if (max_slots < MIN_SLOTS)
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max_slots = MIN_SLOTS;
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else if (max_slots > MAX_SLOTS)
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max_slots = MAX_SLOTS;
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slots = 0;
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records = NULL;
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expand_hashtable();
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}
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/* ================================================== */
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void
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CLG_Finalise(void)
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{
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if (!active)
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return;
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ARR_DestroyInstance(records);
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}
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/* ================================================== */
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void
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CLG_LogNTPAccess(IPAddr *client, time_t now)
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{
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Record *record;
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if (!active)
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return;
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record = get_record(client);
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if (record == NULL)
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return;
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record->ntp_hits++;
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record->last_ntp_hit = now;
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}
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/* ================================================== */
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void
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CLG_LogCommandAccess(IPAddr *client, time_t now)
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{
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Record *record;
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if (!active)
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return;
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record = get_record(client);
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if (record == NULL)
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return;
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record->cmd_hits++;
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record->last_cmd_hit = now;
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}
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/* ================================================== */
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CLG_Status
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CLG_GetClientAccessReportByIndex(int index, RPT_ClientAccessByIndex_Report *report,
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time_t now, unsigned long *n_indices)
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{
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Record *record;
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if (!active)
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return CLG_INACTIVE;
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*n_indices = ARR_GetSize(records);
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if (index < 0 || index >= *n_indices)
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return CLG_INDEXTOOLARGE;
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record = ARR_GetElement(records, index);
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report->ip_addr = record->ip_addr;
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report->ntp_hits = record->ntp_hits;
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report->cmd_hits = record->cmd_hits;
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report->last_ntp_hit_ago = now - record->last_ntp_hit;
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report->last_cmd_hit_ago = now - record->last_cmd_hit;
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return CLG_SUCCESS;
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}
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