NAME¶

getipnodebyname, getipnodebyaddr, freehostent - get network hostnames and addresses

LIBRARY¶

Standard C library (libc, -lc)

SYNOPSIS¶

#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>

[[deprecated]] struct hostent *getipnodebyname(const char *name, int af,
                                            int flags, int *error_num);
[[deprecated]] struct hostent *getipnodebyaddr(const void addr[.len],
                                            size_t len, int af,
                                            int *error_num);
[[deprecated]] void freehostent(struct hostent *ip);

DESCRIPTION¶

These functions are deprecated (and unavailable in glibc). Use getaddrinfo(3) and getnameinfo(3) instead.

The getipnodebyname() and getipnodebyaddr() functions return the names and addresses of a network host. These functions return a pointer to the following structure:

struct hostent {


    char  *h_name;


    char **h_aliases;


    int    h_addrtype;


    int    h_length;


    char **h_addr_list;
};

These functions replace the gethostbyname(3) and gethostbyaddr(3) functions, which could access only the IPv4 network address family. The getipnodebyname() and getipnodebyaddr() functions can access multiple network address families.

Unlike the gethostby functions, these functions return pointers to dynamically allocated memory. The freehostent() function is used to release the dynamically allocated memory after the caller no longer needs the hostent structure.

RETURN VALUE¶

NULL is returned if an error occurred, and error_num will contain an error code from the following list:

HOST_NOT_FOUND

The hostname or network address was not found.

NO_ADDRESS

The domain name server recognized the network address or name, but no answer was returned. This can happen if the network host has only IPv4 addresses and a request has been made for IPv6 information only, or vice versa.

NO_RECOVERY

The domain name server returned a permanent failure response.

TRY_AGAIN

The domain name server returned a temporary failure response. You might have better luck next time.

A successful query returns a pointer to a hostent structure that contains the following fields:

h_name

This is the official name of this network host.

h_aliases

This is an array of pointers to unofficial aliases for the same host. The array is terminated by a null pointer.

h_addrtype

This is a copy of the af argument to getipnodebyname() or getipnodebyaddr(). h_addrtype will always be AF_INET if the af argument was AF_INET. h_addrtype will always be AF_INET6 if the af argument was AF_INET6.

h_length

This field will be set to sizeof(struct in_addr) if h_addrtype is AF_INET, and to sizeof(struct in6_addr) if h_addrtype is AF_INET6.

h_addr_list

This is an array of one or more pointers to network address structures for the network host. The array is terminated by a null pointer.

STANDARDS¶

None.

HISTORY¶

RFC 2553.

Present in glibc 2.1.91-95, but removed again. Several UNIX-like systems support them, but all call them deprecated.

SEE ALSO¶

getaddrinfo(3), getnameinfo(3), inet_ntop(3), inet_pton(3)