DNS

Overview

Macros
#define	LWIP_DNS   0
#define	DNS_TABLE_SIZE   4
#define	DNS_MAX_NAME_LENGTH   256
#define	DNS_MAX_SERVERS   2
#define	DNS_MAX_RETRIES   4
#define	DNS_DOES_NAME_CHECK   1
#define	LWIP_DNS_SECURE   (LWIP_DNS_SECURE_RAND_XID | LWIP_DNS_SECURE_NO_MULTIPLE_OUTSTANDING | LWIP_DNS_SECURE_RAND_SRC_PORT)
#define	DNS_LOCAL_HOSTLIST   0
#define	DNS_LOCAL_HOSTLIST_IS_DYNAMIC   0
#define	LWIP_DNS_SUPPORT_MDNS_QUERIES   0

Macro Definition Documentation

#define LWIP_DNS   0

LWIP_DNS==1: Turn on DNS module. UDP must be available for DNS transport.

#define DNS_TABLE_SIZE   4

DNS maximum number of entries to maintain locally.

#define DNS_MAX_NAME_LENGTH   256

DNS maximum host name length supported in the name table.

#define DNS_MAX_SERVERS   2

The maximum of DNS servers The first server can be initialized automatically by defining DNS_SERVER_ADDRESS(ipaddr), where 'ipaddr' is an 'ip_addr_t*'

#define DNS_MAX_RETRIES   4

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

#define DNS_DOES_NAME_CHECK   1

DNS do a name checking between the query and the response.

#define LWIP_DNS_SECURE   (LWIP_DNS_SECURE_RAND_XID | LWIP_DNS_SECURE_NO_MULTIPLE_OUTSTANDING | LWIP_DNS_SECURE_RAND_SRC_PORT)

LWIP_DNS_SECURE: controls the security level of the DNS implementation Use all DNS security features by default. This is overridable but should only be needed by very small targets or when using against non standard DNS servers.

#define DNS_LOCAL_HOSTLIST   0

DNS_LOCAL_HOSTLIST: Implements a local host-to-address list. If enabled, you have to define an initializer: #define DNS_LOCAL_HOSTLIST_INIT {DNS_LOCAL_HOSTLIST_ELEM("host_ip4", IPADDR4_INIT_BYTES(1,2,3,4)), \ DNS_LOCAL_HOSTLIST_ELEM("host_ip6", IPADDR6_INIT_HOST(123, 234, 345, 456)}

Instead, you can also use an external function: #define DNS_LOOKUP_LOCAL_EXTERN(x) extern err_t my_lookup_function(const char *name, ip_addr_t *addr, u8_t dns_addrtype) that looks up the IP address and returns ERR_OK if found (LWIP_DNS_ADDRTYPE_xxx is passed in dns_addrtype).

#define DNS_LOCAL_HOSTLIST_IS_DYNAMIC   0

If this is turned on, the local host-list can be dynamically changed at runtime.

#define LWIP_DNS_SUPPORT_MDNS_QUERIES   0

Set this to 1 to enable querying ".local" names via mDNS using a One-Shot Multicast DNS Query