/**************************************************************************** * 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 * * Inspired by/based on uIP logic by Adam Dunkels: * * Copyright (c) 2002-2003, Adam Dunkels. All rights reserved. * Author Adam Dunkels * * 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 #include #include #include #include #include /**************************************************************************** * 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 '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 */