DNS resolver
[Apps]

Collaboration diagram for DNS resolver:

Data Structures
struct	dns_hdr
struct	dns_answer
struct	namemap
Files
file	resolv.c
file	resolv.h
Defines
#define	MAX_RETRIES   8
#define	RESOLV_ENTRIES   4
#define	UIP_UDP_APPCALL   resolv_appcall
Typedefs
typedef int	uip_udp_appstate_t
Functions
void	resolv_appcall (void)
void	resolv_query (char *name)
u16_t *	resolv_lookup (char *name)
u16_t *	resolv_getserver (void)
void	resolv_conf (u16_t *dnsserver)
void	resolv_init (void)
void	resolv_found (char *name, u16_t *ipaddr)

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Detailed Description

The uIP DNS resolver functions are used to lookup a hostname and map it to a numerical IP address. It maintains a list of resolved hostnames that can be queried with the resolv_lookup() function. New hostnames can be resolved using the resolv_query() function.

When a hostname has been resolved (or found to be non-existant), the resolver code calls a callback function called resolv_found() that must be implemented by the module that uses the resolver.

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Define Documentation

#define MAX_RETRIES   8

#define RESOLV_ENTRIES   4

#define UIP_UDP_APPCALL   resolv_appcall

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Typedef Documentation

typedef int uip_udp_appstate_t

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Function Documentation

void resolv_appcall

(

void

)

void resolv_conf

(

u16_t *

dnsserver

)

Configure which DNS server to use for queries.

Parameters:

dnsserver

A pointer to a 4-byte representation of the IP address of the DNS server to be configured.

void resolv_found	(	char *	name,
		u16_t *	ipaddr
	)

Callback function which is called when a hostname is found.

This function must be implemented by the module that uses the DNS resolver. It is called when a hostname is found, or when a hostname was not found.

Parameters:

	name	A pointer to the name that was looked up.
	ipaddr	A pointer to a 4-byte array containing the IP address of the hostname, or NULL if the hostname could not be found.

Here is the call graph for this function:

u16_t * resolv_getserver

(

void

)

Obtain the currently configured DNS server.

Returns:

A pointer to a 4-byte representation of the IP address of the currently configured DNS server or NULL if no DNS server has been configured.

void resolv_init

(

void

)

Initalize the resolver.

u16_t * resolv_lookup

(

char *

name

)

Look up a hostname in the array of known hostnames.

Note:

This function only looks in the internal array of known hostnames, it does not send out a query for the hostname if none was found. The function resolv_query() can be used to send a query for a hostname.

Returns:

A pointer to a 4-byte representation of the hostname's IP address, or NULL if the hostname was not found in the array of hostnames.

void resolv_query

(

char *

name

)

Queues a name so that a question for the name will be sent out.

Parameters:

name

The hostname that is to be queried.