netdb.c File Reference

Data Structures
struct	gethostbyname_r_helper
Functions
struct hostent *	lwip_gethostbyname (const char *name)
int	lwip_gethostbyname_r (const char *name, struct hostent *ret, char *buf, size_t buflen, struct hostent **result, int *h_errnop)
void	lwip_freeaddrinfo (struct addrinfo *ai)
int	lwip_getaddrinfo (const char *nodename, const char *servname, const struct addrinfo *hints, struct addrinfo **res)
Variables
int	h_errno

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Detailed Description

API functions for name resolving

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Function Documentation

void lwip_freeaddrinfo

(

struct addrinfo *

ai

)

Frees one or more addrinfo structures returned by getaddrinfo(), along with any additional storage associated with those structures. If the ai_next field of the structure is not null, the entire list of structures is freed.

Parameters:

ai

struct addrinfo to free

int lwip_getaddrinfo	(	const char *	nodename,
		const char *	servname,
		const struct addrinfo *	hints,
		struct addrinfo **	res
	)

Translates the name of a service location (for example, a host name) and/or a service name and returns a set of socket addresses and associated information to be used in creating a socket with which to address the specified service. Memory for the result is allocated internally and must be freed by calling lwip_freeaddrinfo()!

Due to a limitation in dns_gethostbyname, only the first address of a host is returned. Also, service names are not supported (only port numbers)!

Parameters:

	nodename	descriptive name or address string of the host (may be NULL -> local address)
	servname	port number as string of NULL
	hints	structure containing input values that set socktype and protocol
	res	pointer to a pointer where to store the result (set to NULL on failure)

Returns:

0 on success, non-zero on failure

struct hostent* lwip_gethostbyname

(

const char *

name

)

[read]

Returns an entry containing addresses of address family AF_INET for the host with name name. Due to dns_gethostbyname limitations, only one address is returned.

Parameters:

name

the hostname to resolve

Returns:

an entry containing addresses of address family AF_INET for the host with name name

int lwip_gethostbyname_r	(	const char *	name,
		struct hostent *	ret,
		char *	buf,
		size_t	buflen,
		struct hostent **	result,
		int *	h_errnop
	)

Thread-safe variant of lwip_gethostbyname: instead of using a static buffer, this function takes buffer and errno pointers as arguments and uses these for the result.

Parameters:

	name	the hostname to resolve
	ret	pre-allocated struct where to store the result
	buf	pre-allocated buffer where to store additional data
	buflen	the size of buf
	result	pointer to a hostent pointer that is set to ret on success and set to zero on error
	h_errnop	pointer to an int where to store errors (instead of modifying the global h_errno)

Returns:

0 on success, non-zero on error, additional error information is stored in *h_errnop instead of h_errno to be thread-safe

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Variable Documentation

int h_errno

h_errno is exported in netdb.h for access by applications.

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