36abcda0d2
Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
290 lines
8.1 KiB
C
290 lines
8.1 KiB
C
/****************************************************************************
|
|
* libs/libc/netdb/lib_dnscache.c
|
|
*
|
|
* Licensed to the Apache Software Foundation (ASF) under one or more
|
|
* contributor license agreements. See the NOTICE file distributed with
|
|
* this work for additional information regarding copyright ownership. The
|
|
* ASF licenses this file to you under the Apache License, Version 2.0 (the
|
|
* "License"); you may not use this file except in compliance with the
|
|
* License. You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
|
* License for the specific language governing permissions and limitations
|
|
* under the License.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Included Files
|
|
****************************************************************************/
|
|
|
|
#include <nuttx/config.h>
|
|
|
|
#include <sys/time.h>
|
|
#include <string.h>
|
|
#include <time.h>
|
|
#include <assert.h>
|
|
#include <errno.h>
|
|
#include <debug.h>
|
|
|
|
#include "netdb/lib_dns.h"
|
|
|
|
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
|
|
|
|
/****************************************************************************
|
|
* Private Types
|
|
****************************************************************************/
|
|
|
|
/* This described one entry in the cache of resolved hostnames.
|
|
*
|
|
* REVISIT: this consumes extra space, especially when multiple
|
|
* addresses per name are stored.
|
|
*/
|
|
|
|
struct dns_cache_s
|
|
{
|
|
#if CONFIG_NETDB_DNSCLIENT_LIFESEC > 0
|
|
time_t ctime; /* Creation time */
|
|
#endif
|
|
char name[CONFIG_NETDB_DNSCLIENT_NAMESIZE];
|
|
uint8_t naddr; /* How many addresses per name */
|
|
union dns_addr_u addr[CONFIG_NETDB_MAX_IPADDR];
|
|
};
|
|
|
|
/****************************************************************************
|
|
* Private Data
|
|
****************************************************************************/
|
|
|
|
static uint8_t g_dns_head; /* Head of the circular, DNS resolver cache */
|
|
static uint8_t g_dns_tail; /* Tail of the circular, DNS resolver cache */
|
|
|
|
/* This is the DNS resolver cache */
|
|
|
|
static struct dns_cache_s g_dns_cache[CONFIG_NETDB_DNSCLIENT_ENTRIES];
|
|
|
|
/****************************************************************************
|
|
* Private Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: dns_save_answer
|
|
*
|
|
* Description:
|
|
* Save the last resolved hostname in the DNS cache
|
|
*
|
|
* Input Parameters:
|
|
* hostname - The hostname string to be cached.
|
|
* addr - The IP addresses associated with the hostname.
|
|
* naddr - The count of the IP addresses.
|
|
*
|
|
* Returned Value:
|
|
* None
|
|
*
|
|
****************************************************************************/
|
|
|
|
void dns_save_answer(FAR const char *hostname,
|
|
FAR const union dns_addr_u *addr, int naddr)
|
|
{
|
|
FAR struct dns_cache_s *entry;
|
|
#if CONFIG_NETDB_DNSCLIENT_LIFESEC > 0
|
|
struct timespec now;
|
|
#endif
|
|
int next;
|
|
int ndx;
|
|
|
|
naddr = MIN(naddr, CONFIG_NETDB_MAX_IPADDR);
|
|
DEBUGASSERT(naddr >= 1 && naddr <= UCHAR_MAX);
|
|
|
|
/* Get exclusive access to the DNS cache */
|
|
|
|
dns_lock();
|
|
|
|
/* Get the index to the new head of the list */
|
|
|
|
ndx = g_dns_head;
|
|
next = ndx + 1;
|
|
if (next >= CONFIG_NETDB_DNSCLIENT_ENTRIES)
|
|
{
|
|
next = 0;
|
|
}
|
|
|
|
/* If the next head pointer would match the tail index, then increment
|
|
* the tail index, discarding the oldest mapping in the cache.
|
|
*/
|
|
|
|
if (next == g_dns_tail)
|
|
{
|
|
int tmp = g_dns_tail + 1;
|
|
if (tmp >= CONFIG_NETDB_DNSCLIENT_ENTRIES)
|
|
{
|
|
tmp = 0;
|
|
}
|
|
|
|
g_dns_tail = tmp;
|
|
}
|
|
|
|
/* Save the answer in the cache */
|
|
|
|
entry = &g_dns_cache[ndx];
|
|
|
|
#if CONFIG_NETDB_DNSCLIENT_LIFESEC > 0
|
|
/* Get the current time */
|
|
|
|
clock_gettime(CLOCK_MONOTONIC, &now);
|
|
entry->ctime = (time_t)now.tv_sec;
|
|
#endif
|
|
|
|
strlcpy(entry->name, hostname, CONFIG_NETDB_DNSCLIENT_NAMESIZE);
|
|
memcpy(&entry->addr, addr, naddr * sizeof(*addr));
|
|
entry->naddr = naddr;
|
|
|
|
/* Save the updated head index */
|
|
|
|
g_dns_head = next;
|
|
dns_unlock();
|
|
}
|
|
|
|
/****************************************************************************
|
|
* Name: dns_clear_answer
|
|
*
|
|
* Description:
|
|
* Clear the resolved hostname in the DNS cache
|
|
*
|
|
* Returned Value:
|
|
* None
|
|
*
|
|
****************************************************************************/
|
|
|
|
void dns_clear_answer(void)
|
|
{
|
|
/* Get exclusive access to the DNS cache */
|
|
|
|
dns_lock();
|
|
|
|
/* Reset the circular of DNS cache */
|
|
|
|
g_dns_head = 0;
|
|
g_dns_tail = 0;
|
|
|
|
dns_unlock();
|
|
}
|
|
|
|
/****************************************************************************
|
|
* Name: dns_find_answer
|
|
*
|
|
* Description:
|
|
* Check if we already have the resolved hostname address in the cache.
|
|
*
|
|
* Input Parameters:
|
|
* hostname - The hostname string to be resolved.
|
|
* addr - The location to return the IP addresses associated with the
|
|
* hostname.
|
|
* naddr - On entry, the count of addresses backing up the 'addr'
|
|
* pointer. On return, this location will hold the actual count of
|
|
* the returned addresses.
|
|
*
|
|
* Returned Value:
|
|
* If the host name was successfully found in the DNS name resolution
|
|
* cache, zero (OK) will be returned. Otherwise, some negated errno
|
|
* value will be returned, typically -ENOENT meaning that the hostname
|
|
* was not found in the cache.
|
|
*
|
|
****************************************************************************/
|
|
|
|
int dns_find_answer(FAR const char *hostname, FAR union dns_addr_u *addr,
|
|
FAR int *naddr)
|
|
{
|
|
FAR struct dns_cache_s *entry;
|
|
#if CONFIG_NETDB_DNSCLIENT_LIFESEC > 0
|
|
struct timespec now;
|
|
uint32_t elapsed;
|
|
int ret;
|
|
#endif
|
|
int next;
|
|
int ndx;
|
|
|
|
/* Get exclusive access to the DNS cache */
|
|
|
|
dns_lock();
|
|
|
|
#if CONFIG_NETDB_DNSCLIENT_LIFESEC > 0
|
|
/* Get the current time */
|
|
|
|
ret = clock_gettime(CLOCK_MONOTONIC, &now);
|
|
#endif
|
|
|
|
for (ndx = g_dns_tail; ndx != g_dns_head; ndx = next)
|
|
{
|
|
entry = &g_dns_cache[ndx];
|
|
|
|
/* Advance the index for the next time through the loop, handling
|
|
* wrapping to the beginning of the circular buffer.
|
|
*/
|
|
|
|
next = ndx + 1;
|
|
if (next >= CONFIG_NETDB_DNSCLIENT_ENTRIES)
|
|
{
|
|
next = 0;
|
|
}
|
|
|
|
#if CONFIG_NETDB_DNSCLIENT_LIFESEC > 0
|
|
/* Check if this entry has expired
|
|
* REVISIT: Does not this calculation assume that the sizeof(time_t)
|
|
* is equal to the sizeof(uint32_t)?
|
|
*/
|
|
|
|
elapsed = (uint32_t)now.tv_sec - (uint32_t)entry->ctime;
|
|
if (ret >= 0 && elapsed > CONFIG_NETDB_DNSCLIENT_LIFESEC)
|
|
{
|
|
/* This entry has expired. Increment the tail index to exclude
|
|
* this entry on future traversals.
|
|
*/
|
|
|
|
g_dns_tail = next;
|
|
}
|
|
else
|
|
#endif
|
|
{
|
|
/* The entry has not expired, check for a name match. Because
|
|
* the names are truncated to CONFIG_NETDB_DNSCLIENT_NAMESIZE,
|
|
* this has the possibility of aliasing two names and returning
|
|
* the wrong entry from the cache.
|
|
*/
|
|
|
|
if (strncmp(hostname, entry->name,
|
|
CONFIG_NETDB_DNSCLIENT_NAMESIZE) == 0)
|
|
{
|
|
/* We have a match. Return the resolved host address */
|
|
|
|
/* Make sure that the address will fit in the caller-provided
|
|
* buffer.
|
|
*/
|
|
|
|
*naddr = MIN(*naddr, entry->naddr);
|
|
|
|
/* Return the address information */
|
|
|
|
memcpy(addr, &entry->addr, *naddr * sizeof(*addr));
|
|
|
|
dns_unlock();
|
|
return OK;
|
|
}
|
|
}
|
|
}
|
|
|
|
ret = -ENOENT;
|
|
|
|
dns_unlock();
|
|
return ret;
|
|
}
|
|
|
|
#endif /* CONFIG_NETDB_DNSCLIENT_ENTRIES > 0 */
|