ENDHOSTENT(3XNET) X/Open Networking Services Library Functions
NAME
endhostent, gethostbyaddr, gethostbyname, gethostent, sethostent -
network host database functions
SYNOPSIS
cc [
flag ... ]
file ...
-lxnet [
library ... ]
#include <netdb.h>
extern int h_errno;
void endhostent(void)
struct hostent *gethostbyaddr(
const void *addr,
socklen_t len,
int type);
struct hostent *gethostbyname(
const char *name);
struct hostent *gethostent(void)
void sethostent(
int stayopen);
DESCRIPTION
The
gethostent(),
gethostbyaddr(), and
gethostbyname() functions each
return a pointer to a
hostent structure, the members of which contain
the fields of an entry in the network host database.
The
gethostent() function reads the next entry of the database,
opening a connection to the database if necessary.
The
gethostbyaddr() function searches the database and finds an entry
which matches the address family specified by the
type argument and
which matches the address pointed to by the
addr argument, opening a
connection to the database if necessary. The
addr argument is a
pointer to the binary-format (that is, not null-terminated) address
in network byte order, whose length is specified by the
len argument.
The datatype of the address depends on the address family. For an
address of type
AF_INET, this is an
in_addr structure, defined in
<
netinet/in.h>. For an address of type
AF_INET6, there is an
in6_addr structure defined in <
netinet/in.h>.
The
gethostbyname() function searches the database and finds an entry
which matches the host name specified by the
name argument, opening a
connection to the database if necessary. If
name is an alias for a
valid host name, the function returns information about the host name
to which the alias refers, and
name is included in the list of
aliases returned.
The
sethostent() function opens a connection to the network host
database, and sets the position of the next entry to the first entry.
If the
stayopen argument is non-zero, the connection to the host
database will not be closed after each call to
gethostent() (either
directly, or indirectly through one of the other
gethost*() functions).
The
endhostent() function closes the connection to the database.
USAGE
The
gethostent(),
gethostbyaddr(), and
gethostbyname() functions may
return pointers to static data, which may be overwritten by
subsequent calls to any of these functions.
These functions are generally used with the Internet address family.
RETURN VALUES
On successful completion,
gethostbyaddr(),
gethostbyname() and
gethostent() return a pointer to a
hostent structure if the requested
entry was found, and a null pointer if the end of the database was
reached or the requested entry was not found. Otherwise, a null
pointer is returned.
On unsuccessful completion,
gethostbyaddr() and
gethostbyname() functions set
h_errno to indicate the error.
ERRORS
No errors are defined for
endhostent(),
gethostent() and
sethostent().
The
gethostbyaddr() and
gethostbyname() functions will fail in the
following cases, setting
h_errno to the value shown in the list
below. Any changes to
errno are unspecified.
HOST_NOT_FOUND No such host is known.
NO_DATA The server recognised the request and the name but
no address is available. Another type of request
to the name server for the domain might return an
answer.
NO_RECOVERY An unexpected server failure occurred which can not
be recovered.
TRY_AGAIN A temporary and possibly transient error occurred,
such as a failure of a server to respond.
ATTRIBUTES
See
attributes(7) for descriptions of the following attributes:
+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+
SEE ALSO
endservent(3XNET),
htonl(3XNET),
inet_addr(3XNET),
attributes(7),
standards(7) November 1, 2003 ENDHOSTENT(3XNET)
