getipnodebyname, getipnodebyaddr, freehostent — get network host names and addresses
#include <sys/types.h> #include <sys/socket.h> #include <netdb.h>
struct hostent *getipnodebyname( |
const char * | name, |
int | af, | |
int | flags, | |
int * | error_num) ; |
struct hostent *getipnodebyaddr( |
const void * | addr, |
size_t | len, | |
int | af, | |
int * | error_num) ; |
void
freehostent( |
struct hostent * | ip) ; |
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:
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 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.
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_DEFAULT
This flag is equivalent to (AI_ADDRCONFIG | AI_V4MAPPED).
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 struct in_addr and
len
must be
set to sizeof(struct
in_addr).
AF_INET6
The addr
parameter points to a struct in6_addr and
len
must be
set to sizeof(struct
in6_addr).
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
contains the following fields:
This is the official name of this network host.
This is an array of pointers to unofficial aliases for the same host. The array is terminated by a null pointer.
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
.
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.
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.
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 deprecated.
getaddrinfo(3), getnameinfo(3), inet_ntop(3), inet_pton(3)
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