Originální popis anglicky:
getipnodebyname, getipnodebyaddr, freehostent - get network host names and
addresses
Návod, kniha: Linux Programmer's Manual
#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:
- 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(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.
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.
RFC 2553.
getaddrinfo(3),
getnameinfo(3),
inet_ntop(3),
inet_pton(3)
