NETDB.H(3HEAD) Headers NETDB.H(3HEAD)

NAME

netdb.h, netdb - definitions for network database operations

SYNOPSIS

#include <netdb.h>

DESCRIPTION

The <netdb.h> header defines the type in_port_t and the type in_addr_t as
described in in.h(3HEAD).


The <netdb.h> header defines the hostent structure that includes the
following members:

char *h_name /* official name of the host */
char **h_aliases /* pointer to an array of pointers to
alternative host names, terminated
by a null pointer */
int h_addrtype /* address type */
int h_length /* length, in bytes, of the address */
char **h_addr_list /* pointer to an array of pointers to
network addresses (in network byte
order)for the host, terminated by a
null pointer */


The <netdb.h> header defines the netent structure that includes the
following members:

char *n_name /* official, fully-qualified */
(including the domain) name
of the network */
char **n_aliases /* pointer to an array of pointers to
alternative network names, terminated */
by a null pointer */
int n_addrtype /* the address type of the network */
in_addr_t n_net /* the network number, in host byte order */


The <netdb.h> header defines the protoent structure that includes the
following members:

char *p_name /* official name of the protocol */
char **p_aliases /* pointer to an array of pointers to
alternative protocol names, terminated
by a null pointer */
int p_proto /* protocol number */


The <netdb.h> header defines the servent structure that includes the
following members:

char *s_name /* oficial name of the service */
char **s_aliases /* pointer to an array of pointers to
alternativeservice names, terminated by
a null pointer */
int s_port /* port number at which the service
resides, in network byte order */
char *s_proto /* name of the protocol to use when
contacting the service */


The <netdb.h> header defines the macro IPPORT_RESERVED with the value of
the highest reserved Internet port number.


The <netdb.h> header provides a declaration for h_errno:


extern int h_errno;


The <netdb.h> header defines the following macros for use as error values
for gethostbyaddr() and gethostbyname():


HOST_NOT_FOUND NO_DATA
NO_RECOVERY TRY_AGAIN


Inclusion of the <netdb.h> header may also make visible all symbols from
in.h(3HEAD).

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+

SEE ALSO

Intro(3), in.h(3HEAD), endhostent(3NSL), endnetent(3SOCKET),
endprotoent(3SOCKET), endservent(3SOCKET), endhostent(3XNET),
endnetent(3XNET), endprotoent(3XNET), endservent(3XNET), attributes(7),
standards(7)

September 10, 2004 NETDB.H(3HEAD)