dns.c File Reference

#include "lwip/opt.h"
#include "lwip/def.h"
#include "lwip/udp.h"
#include "lwip/mem.h"
#include "lwip/memp.h"
#include "lwip/dns.h"
#include "lwip/prot/dns.h"
#include <string.h>

Data Structures
struct	dns_query
struct	dns_answer
struct	dns_table_entry
struct	dns_req_entry

Macros
#define	DNS_RAND_TXID   LWIP_RAND
#define	DNS_PORT_ALLOWED(port)   ((port) >= 1024)
#define	DNS_MAX_RETRIES   4
#define	DNS_MAX_TTL   604800

Functions
void	dns_init (void)
void	dns_setserver (u8_t numdns, const ip_addr_t *dnsserver)
const ip_addr_t *	dns_getserver (u8_t numdns)
void	dns_tmr (void)
err_t	dns_gethostbyname (const char *hostname, ip_addr_t *addr, dns_found_callback found, void *callback_arg)
err_t	dns_gethostbyname_addrtype (const char *hostname, ip_addr_t *addr, dns_found_callback found, void *callback_arg, u8_t dns_addrtype)

Detailed Description

DNS - host name to IP address resolver.

Macro Definition Documentation

DNS_MAX_RETRIES

#define DNS_MAX_RETRIES   4

DNS maximum number of retries when asking for a name, before "timeout".

DNS_MAX_TTL

#define DNS_MAX_TTL   604800

DNS resource record max. TTL (one week as default)

DNS_PORT_ALLOWED

#define DNS_PORT_ALLOWED

(

port

)

((port) >= 1024)

Limits the source port to be >= 1024 by default

DNS_RAND_TXID

#define DNS_RAND_TXID   LWIP_RAND

Random generator function to create random TXIDs and source ports for queries

Function Documentation

dns_init()

void dns_init

(

void

)

Initialize the resolver: set up the UDP pcb and configure the default server (if DNS_SERVER_ADDRESS is set).

dns_tmr()

void dns_tmr

(

void

)

The DNS resolver client timer - handle retries and timeouts and should be called every DNS_TMR_INTERVAL milliseconds (every second by default).