94a13982eb
* Implement DNS query over TCP * Implement TCP fallback on responses with the TC bit set References: * https://www.ietf.org/rfc/rfc2181.txt * http://www.dnsflagday.net/2020/ * https://www.netmeister.org/blog/dns-size.html
292 lines
8.9 KiB
C
292 lines
8.9 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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* 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(sa_family_t family, bool stream);
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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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