'\" te
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.TH NETDB.H 3HEAD "Sep 10, 2004"
.SH NAME
netdb.h, netdb \- definitions for network database operations
.SH SYNOPSIS
.LP
.nf
\fB#include <netdb.h>\fR
.fi

.SH DESCRIPTION
.sp
.LP
The <\fBnetdb.h\fR> header defines the type \fBin_port_t\fR and the type
\fBin_addr_t\fR as described in \fBin.h\fR(3HEAD).
.sp
.LP
The <\fBnetdb.h\fR> header defines the \fBhostent\fR structure that includes
the following members:
.sp
.in +2
.nf
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 */
.fi
.in -2

.sp
.LP
The <\fBnetdb.h\fR> header defines the \fBnetent\fR structure that includes the
following members:
.sp
.in +2
.nf
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 */
.fi
.in -2

.sp
.LP
The <\fBnetdb.h\fR> header defines the \fBprotoent\fR structure that includes
the following members:
.sp
.in +2
.nf
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 */
.fi
.in -2

.sp
.LP
The <\fBnetdb.h\fR> header defines the \fBservent\fR structure that includes
the following members:
.sp
.in +2
.nf
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 */
.fi
.in -2

.sp
.LP
The <\fBnetdb.h\fR> header defines the macro \fBIPPORT_RESERVED\fR with the
value of the highest reserved Internet port number.
.sp
.LP
The <\fBnetdb.h\fR> header provides a declaration for \fBh_errno\fR:
.sp
.LP
extern int h_errno;
.sp
.LP
The <\fBnetdb.h\fR> header defines the following macros for use as error values
for \fBgethostbyaddr()\fR and \fBgethostbyname()\fR:
.sp

.sp
.TS
l l
l l .
\fBHOST_NOT_FOUND\fR	\fBNO_DATA\fR
\fBNO_RECOVERY\fR	\fBTRY_AGAIN\fR
.TE

.sp
.LP
Inclusion of the <\fBnetdb.h\fR> header may also make visible all symbols from
\fBin.h\fR(3HEAD).
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
.TE

.SH SEE ALSO
.sp
.LP
\fBIntro\fR(3), \fBendhostent\fR(3NSL), \fBendhostent\fR(3XNET),
\fBendnetent\fR(3SOCKET), \fBendnetent\fR(3XNET), \fBendprotoent\fR(3SOCKET),
\fBendprotoent\fR(3XNET), \fBendservent\fR(3SOCKET), \fBendservent\fR(3XNET),
\fBin.h\fR(3HEAD), \fBattributes\fR(5), \fBstandards\fR(5)