getipnodebyname(3) Linux Programmer's Manual getipnodebyname(3)
NAME
getipnodebyname, getipnodebyaddr, freehostent - get network host names
and addresses
SYNOPSIS
#include<sys/types.h>
#include<sys/socket.h>
#include<netdb.h>
structhostent*getipnodebyname(constchar*name,
int af,int flags,
int*error_num);
structhostent*getipnodebyaddr(constvoid*addr,
size_t len,int af,
int*error_num);
voidfreehostent(structhostent*ip);
DESCRIPTION
These functions are deprecated. Use getaddrinfo(3) and getnameinfo(3)
instead.
The getipnodebyname(3) and getipnodebyaddr(3) functions return the
names and addresses of a network host. These functions return a
pointer to the following structure:
structhostent{
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) func-
tions, which could only access the IPv4 network address family. The
getipnodebyname(3) and getipnodebyaddr(3) functions can access multiple
network address families.
Unlike the gethostby functions, these functions return pointers to
dynamically allocated memory. The freehostent(3) function is used to
release the dynamically allocated memory after the caller no longer
needs the hostent structure.
getipnodebynameparameters
The getipnodebyname(3) function looks up network addresses for the host
specified by the name parameter. The af parameter specifies one of the
following values:
AF_INET
The name parameter points to a dotted-quad IPv4 address or a
name of an IPv4 network host.
AF_INET6
The name parameter points to a hexadecimal IPv6 address or a
name of an IPv6 network host.
The flags parameter specifies additional options. More than one option
can be specified by logically OR-ing them together. flags should be
set to 0 if no options are desired.
AI_V4MAPPED
This flag is used with AF_INET6 to request a query for IPv4
addresses instead of IPv6 addresses; the IPv4 addresses will be
mapped to IPv6 addresses.
AI_ALL This flag is used with AI_V4MAPPED to request a query for both
IPv4 and IPv6 addresses. Any IPv4 address found will be mapped
to an IPv6 address.
AI_ADDRCONFIG
This flag is used with AF_INET6 to further request that queries
for IPv6 addresses should not be made unless the system has at
least one IPv6 address assigned to a network interface, and that
queries for IPv4 addresses should not be made unless the system
has at least one IPv4 address assigned to a network interface.
This flag may be used by itself or with the AI_V4MAPPED flag.
AI_ALL This flag is equivalent to (AI_ADDRCONFIG|AI_V4MAPPED).
getipnodebyaddrparameters
The getipnodebyaddr(3) function looks up the name of the host whose
network address is specified by the addr parameter. The af parameter
specifies one of the following values:
AF_INET
The addr parameter points to a structin_addr and len must be
set to sizeof(structin_addr).
AF_INET6
The addr parameter points to a structin6_addr and len must be
set to sizeof(structin6_addr).
RETURNVALUE
A null pointer is returned if an error occurred, and error_num will
contain an error code from the following list:
HOST_NOT_FOUND
The host name 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 con-
tains 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 parameter to getipnodebyname(3) or
getipnodebyaddr(3). h_addrtype will always be AF_INET if the af
parameter was AF_INET. h_addrtype will always be AF_INET6 if
the af parameter was AF_INET6.
h_length
This field will be set to sizeof(structin_addr) if h_addrtype
is AF_INET, and to sizeof(structin6_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.
NOTES
These functions have been present in glibc 2.1.91-95, but were removed
again. Several Unix-like systems support them, but all call them depre-
cated.
CONFORMINGTO
RFC 2553.
SEEALSO
getaddrinfo(3), getnameinfo(3), inet_ntop(3), inet_pton(3)
Linux Man Page 2002-04-03 getipnodebyname(3)
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