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nuttx/libc/netdb/lib_dns.h

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/****************************************************************************
* libc/netdb/lib_dns.h
* DNS resolver code header file.
*
* Copyright (C) 2007-2009, 2011-2012, 2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Inspired by/based on uIP logic by Adam Dunkels:
*
* Copyright (c) 2002-2003, Adam Dunkels. All rights reserved.
* Author Adam Dunkels <adam@dunkels.com>
*
* 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. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
*
****************************************************************************/
#ifndef __LIBC_NETDB_LIB_DNS_H
#define __LIBC_NETDB_LIB_DNS_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdbool.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <nuttx/net/netconfig.h>
#include <nuttx/net/dns.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* DNS client configuration **************************************************/
#ifndef CONFIG_NETDB_DNSCLIENT_ENTRIES
# define CONFIG_NETDB_DNSCLIENT_ENTRIES 4
#endif
#define RESOLV_ENTRIES CONFIG_NETDB_DNSCLIENT_ENTRIES
#ifndef CONFIG_NETDB_DNSCLIENT_MAXRESPONSE
# define CONFIG_NETDB_DNSCLIENT_MAXRESPONSE 96
#endif
#ifndef CONFIG_NETDB_DNSCLIENT_NAMESIZE
# define CONFIG_NETDB_DNSCLIENT_NAMESIZE 32
#endif
#ifndef CONFIG_NETDB_DNSCLIENT_LIFESEC
# define CONFIG_NETDB_DNSCLIENT_LIFESEC 3600
#endif
#ifndef CONFIG_NETDB_RESOLVCONF_PATH
# define CONFIG_NETDB_RESOLVCONF_PATH "/etc/resolv.conf"
#endif
#define DNS_MAX_ADDRSTR 48
#define DNS_MAX_LINE 64
#define NETDB_DNS_KEYWORD "nameserver"
/****************************************************************************
* Public Types
****************************************************************************/
/* This describes either an IPv4 or IPv6 address. It is essentially a named
* alternative to sockaddr_storage.
*/
union dns_server_u
{
struct sockaddr addr; /* Common address representation */
#ifdef CONFIG_NET_IPv4
struct sockaddr_in ipv4; /* IPv4 address */
#endif
#ifdef CONFIG_NET_IPv6
struct sockaddr_in6 ipv6; /* IPv6 address */
#endif
};
/****************************************************************************
* Public Data
****************************************************************************/
#undef EXTERN
#if defined(__cplusplus)
#define EXTERN extern "C"
extern "C"
{
#else
#define EXTERN extern
#endif
#ifndef CONFIG_NETDB_RESOLVCONF
/* The DNS server address */
EXTERN union dns_server_u g_dns_server;
EXTERN bool g_dns_address; /* true: We have the address of the DNS server */
#endif
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
/****************************************************************************
* Name: dns_initialize
*
* Description:
* Make sure that the DNS client has been properly initialized for use.
*
****************************************************************************/
bool dns_initialize(void);
/****************************************************************************
* Name: dns_semtake
*
* Description:
* Take the DNS semaphore, ignoring errors do to the receipt of signals.
*
****************************************************************************/
void dns_semtake(void);
/****************************************************************************
* Name: dns_semgive
*
* Description:
* Release the DNS semaphore
*
****************************************************************************/
void dns_semgive(void);
/****************************************************************************
* Name: dns_bind
*
* Description:
* Initialize the DNS resolver and return a socket bound to the DNS name
* server. The name server was previously selected via dns_server().
*
* Input Parameters:
* None
*
* Returned Value:
* On success, the bound, non-negative socket descriptor is returned. A
* negated errno value is returned on any failure.
*
****************************************************************************/
int dns_bind(void);
/****************************************************************************
* Name: dns_query
*
* Description:
* Using the DNS resolver socket (sd), look up the the 'hostname', and
* return its IP address in 'ipaddr'
*
* Input Parameters:
* sd - The socket descriptor previously initialized by dsn_bind().
* hostname - The hostname string to be resolved.
* addr - The location to return the IP address associated with the
* hostname
* addrlen - On entry, the size of the buffer backing up the 'addr'
* pointer. On return, this location will hold the actual size of
* the returned address.
*
* Returned Value:
* Returns zero (OK) if the query was successful.
*
****************************************************************************/
int dns_query(int sd, FAR const char *hostname, FAR struct sockaddr *addr,
FAR socklen_t *addrlen);
/****************************************************************************
* Name: dns_save_answer
*
* Description:
* Same the last resolved hostname in the DNS cache
*
* Input Parameters:
* hostname - The hostname string to be cached.
* addr - The IP address associated with the hostname
* addrlen - The size of the of the IP address.
*
* Returned Value:
* None
*
****************************************************************************/
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
void dns_save_answer(FAR const char *hostname,
FAR const struct sockaddr *addr, socklen_t addrlen);
#endif
/****************************************************************************
* 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 address associated with the
* hostname
* addrlen - On entry, the size of the buffer backing up the 'addr'
* pointer. On return, this location will hold the actual size of
* the returned address.
*
* 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.
*
****************************************************************************/
#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
int dns_find_answer(FAR const char *hostname, FAR struct sockaddr *addr,
FAR socklen_t *addrlen);
#endif
#undef EXTERN
#if defined(__cplusplus)
}
#endif
#endif /* __LIBC_NETDB_LIB_DNS_H */
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