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nuttxs
7b3913da60
1. Adopt an exponential backoff strategy () to dynamically adjust the timeout duration, which is suitable for retry scenarios. 2. Optimize the default configuration to set the initial timeout to 5 seconds. 3. Support dynamic modification of the maximum timeout limit to adapt to different scenarios. Reference: RFC 1536 (section on retransmission implementation recommendations) Signed-off-by: nuttxs <zhaoqing.zhang@sony.com>
295 lines
9.0 KiB
C
295 lines
9.0 KiB
C
/****************************************************************************
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* libs/libc/netdb/lib_dns.h
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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#ifndef __LIBS_LIBC_NETDB_LIB_DNS_H
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#define __LIBS_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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#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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#ifndef CONFIG_NETDB_DNSSERVER_NAMESERVERS
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# define CONFIG_NETDB_DNSSERVER_NAMESERVERS 1
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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_addr_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 addresses */
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EXTERN union dns_addr_u g_dns_servers[];
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EXTERN uint8_t g_dns_nservers;
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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_lock
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*
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* Description:
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* Take the DNS mutex, ignoring errors due to the receipt of signals.
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*
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****************************************************************************/
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void dns_lock(void);
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/****************************************************************************
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* Name: dns_unlock
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*
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* Description:
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* Release the DNS mutex
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*
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****************************************************************************/
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void dns_unlock(void);
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/****************************************************************************
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* Name: dns_breaklock
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*
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* Description:
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* Break the DNS lock
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*
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****************************************************************************/
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void dns_breaklock(FAR unsigned int *count);
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/****************************************************************************
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* Name: dns_restorelock
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*
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* Description:
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* Restore the DNS lock
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*
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****************************************************************************/
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void dns_restorelock(unsigned int count);
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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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* family - Address family (AF_INET or AF_INET6)
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* stream - Whether to use stream socket
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* retry_count - Current retry attempt (0 for first attempt)
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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(sa_family_t family, bool stream, int retry_count);
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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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* hostname - The hostname string to be resolved.
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* addr - The location to return the IP addresses associated with the
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* hostname.
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* naddr - On entry, the count of addresses backing up the 'addr'
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* pointer. On return, this location will hold the actual count of
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* the returned addresses.
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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(FAR const char *hostname, FAR union dns_addr_u *addr,
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FAR int *naddr);
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/****************************************************************************
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* Name: dns_is_queryfamily
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*
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* Description:
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* Determine if the specified address family is available for DNS query.
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*
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* Input Parameters:
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* family - The address family. AF_INET or AF_INET6 is specified.
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*
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* Returned Value:
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* Returns true if the address family specified in the family argument
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* is available.
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*
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****************************************************************************/
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bool dns_is_queryfamily(sa_family_t family);
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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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* Save 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 addresses associated with the hostname.
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* naddr - The count of the IP addresses.
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* ttl - The TTL of the IP addresses.
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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 union dns_addr_u *addr, int naddr,
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uint32_t ttl);
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#endif
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/****************************************************************************
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* Name: dns_clear_answer
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*
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* Description:
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* Clear the resolved hostname in the DNS cache
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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_clear_answer(void);
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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 addresses associated with the
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* hostname.
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* naddr - On entry, the count of addresses backing up the 'addr'
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* pointer. On return, this location will hold the actual count of
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* the returned addresses.
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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 union dns_addr_u *addr,
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FAR int *naddr);
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#endif
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/****************************************************************************
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* Name: dns_notify_nameserver
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****************************************************************************/
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void dns_notify_nameserver(FAR const struct sockaddr *addr,
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socklen_t addrlen);
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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 /* __LIBS_LIBC_NETDB_LIB_DNS_H */
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