255 lines
8.3 KiB
C
255 lines
8.3 KiB
C
/****************************************************************************
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* libc/netdb/lib_dns.h
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* DNS resolver code header file.
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*
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* Copyright (C) 2007-2009, 2011-2012, 2014 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Inspired by/based on uIP logic by Adam Dunkels:
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*
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* Copyright (c) 2002-2003, Adam Dunkels. All rights reserved.
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* Author Adam Dunkels <adam@dunkels.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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#ifndef __LIBC_NETDB_LIB_DNS_H
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#define __LIBC_NETDB_LIB_DNS_H
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdbool.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <nuttx/net/netconfig.h>
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#include <nuttx/net/dns.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* DNS client configuration **************************************************/
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#ifndef CONFIG_NETDB_DNSCLIENT_ENTRIES
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# define CONFIG_NETDB_DNSCLIENT_ENTRIES 4
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#endif
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#define RESOLV_ENTRIES CONFIG_NETDB_DNSCLIENT_ENTRIES
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#ifndef CONFIG_NETDB_DNSCLIENT_MAXRESPONSE
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# define CONFIG_NETDB_DNSCLIENT_MAXRESPONSE 96
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#endif
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#ifndef CONFIG_NETDB_DNSCLIENT_NAMESIZE
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# define CONFIG_NETDB_DNSCLIENT_NAMESIZE 32
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#endif
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#ifndef CONFIG_NETDB_DNSCLIENT_LIFESEC
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# define CONFIG_NETDB_DNSCLIENT_LIFESEC 3600
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#endif
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#ifndef CONFIG_NETDB_RESOLVCONF_PATH
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# define CONFIG_NETDB_RESOLVCONF_PATH "/etc/resolv.conf"
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#endif
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#define DNS_MAX_ADDRSTR 48
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#define DNS_MAX_LINE 64
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#define NETDB_DNS_KEYWORD "nameserver"
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/****************************************************************************
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* Public Types
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****************************************************************************/
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/* This describes either an IPv4 or IPv6 address. It is essentially a named
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* alternative to sockaddr_storage.
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*/
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union dns_server_u
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{
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struct sockaddr addr; /* Common address representation */
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#ifdef CONFIG_NET_IPv4
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struct sockaddr_in ipv4; /* IPv4 address */
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#endif
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#ifdef CONFIG_NET_IPv6
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struct sockaddr_in6 ipv6; /* IPv6 address */
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#endif
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};
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/****************************************************************************
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* Public Data
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****************************************************************************/
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#undef EXTERN
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#if defined(__cplusplus)
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#define EXTERN extern "C"
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extern "C"
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{
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#else
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#define EXTERN extern
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#endif
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#ifndef CONFIG_NETDB_RESOLVCONF
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/* The DNS server address */
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EXTERN union dns_server_u g_dns_server;
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EXTERN bool g_dns_address; /* true: We have the address of the DNS server */
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#endif
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/****************************************************************************
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* Public Function Prototypes
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****************************************************************************/
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/****************************************************************************
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* Name: dns_initialize
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*
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* Description:
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* Make sure that the DNS client has been properly initialized for use.
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*
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****************************************************************************/
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bool dns_initialize(void);
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/****************************************************************************
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* Name: dns_semtake
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*
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* Description:
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* Take the DNS semaphore, ignoring errors do to the receipt of signals.
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*
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****************************************************************************/
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void dns_semtake(void);
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/****************************************************************************
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* Name: dns_semgive
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*
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* Description:
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* Release the DNS semaphore
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*
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****************************************************************************/
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void dns_semgive(void);
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/****************************************************************************
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* Name: dns_bind
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*
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* Description:
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* Initialize the DNS resolver and return a socket bound to the DNS name
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* server. The name server was previously selected via dns_server().
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*
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* Input Parameters:
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* None
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*
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* Returned Value:
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* On success, the bound, non-negative socket descriptor is returned. A
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* negated errno value is returned on any failure.
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*
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****************************************************************************/
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int dns_bind(void);
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/****************************************************************************
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* Name: dns_query
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*
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* Description:
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* Using the DNS resolver socket (sd), look up the 'hostname', and
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* return its IP address in 'ipaddr'
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*
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* Input Parameters:
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* sd - The socket descriptor previously initialized by dsn_bind().
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* hostname - The hostname string to be resolved.
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* addr - The location to return the IP address associated with the
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* hostname
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* addrlen - On entry, the size of the buffer backing up the 'addr'
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* pointer. On return, this location will hold the actual size of
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* the returned address.
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*
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* Returned Value:
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* Returns zero (OK) if the query was successful.
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*
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****************************************************************************/
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int dns_query(int sd, FAR const char *hostname, FAR struct sockaddr *addr,
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FAR socklen_t *addrlen);
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/****************************************************************************
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* Name: dns_save_answer
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*
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* Description:
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* Same the last resolved hostname in the DNS cache
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*
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* Input Parameters:
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* hostname - The hostname string to be cached.
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* addr - The IP address associated with the hostname
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* addrlen - The size of the of the IP address.
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
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void dns_save_answer(FAR const char *hostname,
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FAR const struct sockaddr *addr, socklen_t addrlen);
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#endif
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/****************************************************************************
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* Name: dns_find_answer
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*
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* Description:
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* Check if we already have the resolved hostname address in the cache.
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*
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* Input Parameters:
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* hostname - The hostname string to be resolved.
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* addr - The location to return the IP address associated with the
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* hostname
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* addrlen - On entry, the size of the buffer backing up the 'addr'
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* pointer. On return, this location will hold the actual size of
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* the returned address.
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*
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* Returned Value:
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* If the host name was successfully found in the DNS name resolution
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* cache, zero (OK) will be returned. Otherwise, some negated errno
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* value will be returned, typically -ENOENT meaning that the hostname
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* was not found in the cache.
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*
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****************************************************************************/
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#if CONFIG_NETDB_DNSCLIENT_ENTRIES > 0
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int dns_find_answer(FAR const char *hostname, FAR struct sockaddr *addr,
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FAR socklen_t *addrlen);
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#endif
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#undef EXTERN
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#if defined(__cplusplus)
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}
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#endif
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#endif /* __LIBC_NETDB_LIB_DNS_H */
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