getnetbyaddr(3)getnetbyaddr(3)NAME
getnetbyaddr, getnetbyaddr_r - Get a network entry by address
SYNOPSIS
#include <netdb.h>
struct netent *getnetbyaddr(
in_addr_t num,
int type );
[Tru64 UNIX] The following obsolete function is supported in order to
maintain backward compatibility with previous versions of the operating
system. You should not use it in new designs. int getnetbyaddr_r(
int num,
int type,
struct netent *net,
struct netent_data *net_data );
[Tru64 UNIX] The following definition of the getnetbyaddr() function
does not conform to current standards and is supported only for back‐
ward compatibility: struct netent *getnetbyaddr(
int num,
int type );
LIBRARY
Standard C Library (libc)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
getnetbyaddr(): XNS4.0, XNS5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Specifies the number of the network in host-byte order. [Tru64
UNIX] For getnetbyaddr_r(), this points to the netent structure. The
netdb.h header file defines the netent structure. Specifies the Inter‐
net domain address format. The value AF_INET must be used. [Tru64
UNIX] Specifies the number of the network in host-byte order. [Tru64
UNIX] Is data for the networks database. The netdb.h header file
defines the netent_data structure.
DESCRIPTION
The getnetbyaddr() function returns a pointer to a structure of type
netent. Its members specify data obtained from either the local
/etc/networks file or the NIS distributed networks file. To determine
which file or files to search, and in which order, the system uses the
switches in the /etc/svc.conf file. The netdb.h header file defines
the netent structure.
The getnetbyaddr() function searches the network database file sequen‐
tially until a match with the num and type parameters occurs. The num
parameter must specify the network number in host-byte order. The type
parameter must be the constant AF_INET. When EOF (End-of-File) is
reached without a match, an error value is returned by this parameter.
Use the endnetent() function to close the networks file.
NOTES
The getnetbyaddr() function and its backward compatible version return
a pointer to thread-specific data. Subsequent calls to these or
related functions from the same thread overwrite this data.
[Tru64 UNIX] The getnetbyaddr_r() function is an obsolete reentrant
version of the getnetbyaddr() function. It is supported in order to
maintain backward compatibility with previous versions of the operating
system and should not be used in new designs. Note that you must set
the net_fp field of the netent_data structure to NULL before its first
access by either the setnetent_r() or getnetbyaddr_r() function.
You must initialize the _net_stayopen option of the netent_data struc‐
ture if you are not using the setnetent() function.
RETURN VALUES
Upon successful completion, the getnetbyaddr() function and its back‐
ward compatible version return a pointer to a netent structure. If it
fails or reaches the end of the /etc/networks name file, it returns a
null pointer.
[Tru64 UNIX] Upon successful completion, the getnetbyaddr_r() function
stores the netent structure in the location pointed to by net, and
returns a value of 0 (zero). Upon failure, it returns a value of -1.
ERRORS
Current industry standards do not define error values for the getnet‐
byaddr() function.
[Tru64 UNIX] If any of the following conditions occurs, the getnet‐
byaddr_r() function sets errno to the corresponding value:
The net or net_data parameter is invalid. The search failed.
FILES
The Internet network name database file. Each record in the file occu‐
pies a single line and has three fields: the official network name, the
network number, and alias.
SEE ALSO
Functions: endnetent(3), getnetent(3), getnetbyname(3), setnetent(3).
Files: networks(4), svc.conf(4).
Networks: nis_intro(7).
Standards: standards(5).
Network Programmer's Guide
getnetbyaddr(3)