Network address database functionality. More...

#include <sys/cdefs.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <inttypes.h>

Data Structures
struct	hostent
	Network host entry. More...

struct	addrinfo
	Network address information structure. More...

Macros
#define	h_addr h_addr_list[0]
	Primary network address. More...

#define	HOST_NOT_FOUND 1
	Hostname not found. More...

#define	TRY_AGAIN 2
	Try the request again. More...

#define	NO_RECOVERY 3
	A non-recoverable error. More...

#define	NO_DATA 4
	Host found, but no data. More...

#define	EAI_AGAIN 1
	Try the request again. More...

#define	EAI_BADFLAGS 2
	Invalid hint flags. More...

#define	EAI_FAIL 3
	A non-recoverable error. More...

#define	EAI_FAMILY 4
	Invalid address family. More...

#define	EAI_MEMORY 5
	Memory allocation error. More...

#define	EAI_NONAME 6
	Hostname not found. More...

#define	EAI_SERVICE 7
	Invalid service value. More...

#define	EAI_SOCKTYPE 8
	Invalid socket type. More...

#define	EAI_SYSTEM 9
	System error, check errno. More...

#define	EAI_OVERFLOW 10
	Argument buffer overflow. More...

#define	AI_PASSIVE 0x00000001
	Address intended for bind(). More...

#define	AI_CANONNAME 0x00000002
	Request canonical name. More...

#define	AI_NUMERICHOST 0x00000004
	Inhibit host resolution. More...

#define	AI_NUMERICSERV 0x00000008
	Inhibit service resolution. More...

#define	AI_V4MAPPED 0x00000010
	Return v4-mapped IPv6 addrs. More...

#define	AI_ALL 0x00000020
	Query for both IPv4 and IPv6. More...

#define	AI_ADDRCONFIG 0x00000040
	Only query for IPv4/IPv6 addrs the system has a valid addr. More...

Functions
void	freeaddrinfo (struct addrinfo *ai)
	Free an address information structure returned by getaddrinfo(). More...

int	getaddrinfo (const char nodename, const char servname, const struct addrinfo hints, struct addrinfo *res)
	Get information about a specified addresss. More...

struct hostent *	gethostbyname (const char *name)
	Look up a host by its name. More...

struct hostent *	gethostbyname2 (const char *name, int af)
	Look up a host by its name and address family. More...

Variables
int	h_errno
	Error value for gethostbyname(). More...

Detailed Description

Network address database functionality.

This file contains functions related to network address lookups, usually performed through DNS.

Author: Lawrence Sebald

Macro Definition Documentation

#define h_addr h_addr_list[0]

Primary network address.

Function Documentation

void freeaddrinfo ( struct addrinfo * ai )

Free an address information structure returned by getaddrinfo().

This function cleans up any memory associated with the specified struct addrinfo, which was returned previously by a call to getaddrinfo().

Parameters

ai	The struct addrinfo to clean up.

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

Get information about a specified addresss.

This function translates the name of a host and service into a set of socket addresses and related information to be used in creating a socket. This includes potentially looking up the host information in the network address database (and thus in DNS possibly as well).

Parameters

nodename	The host to look up.
servname	The service to look up.
hints	Hints used in aiding lookup.
res	The resulting address information.

Returns: 0 on success, non-zero error code on failure.

See also: Errors for the getaddrinfo() function

struct hostent* gethostbyname ( const char * name )

Look up a host by its name.

This function queries the network address database (possibly recursively) for the network address of the specified hostname. This will first search any local databases before querying remote databases (such as a DNS server) for the host specified.

Parameters

name	The hostname to look up.

Returns: A pointer to a host entry on success or NULL on failure. h_errno is set on failure to indicate the error that occurred.

Note: This function is non-reentrant. getaddrinfo() should (in general) be used instead of this function.

struct hostent* gethostbyname2	(	const char *	name,
		int	af
	)

Look up a host by its name and address family.

This function queries the network address database (possibly recursively) for the network address of the specified hostname. This will first search any local databases before querying remote databases (such as a DNS server) for the host specified.

This function allows you to specify the address family that you wish the returned hostent to contain. This function is a GNU extension and has not been specified by any POSIX specification.

Parameters

name	The hostname to look up.
af	The address family to use for lookups (AF_INET or AF_INET6).

Returns: A pointer to a host entry on success or NULL on failure. h_errno is set on failure to indicate the error that occurred.

Note: This function is non-reentrant. getaddrinfo() should (in general) be used instead of this function.

Variable Documentation

int h_errno

Error value for gethostbyname().

See also: Error values for the h_errno variable

Data Structures

Macros

Functions

Variables

Detailed Description

Macro Definition Documentation

Function Documentation

Variable Documentation