getnetbyaddr(3) Library Functions Manual getnetbyaddr(3)
NAME
getnetbyaddr, getnetbyaddr_r - Get a network entry by address
LIBRARY
Standard C Library (libc.so, libc.a)
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 oper-
ating 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);
STANDARDS
Interfaces documented on this reference page conform to industry standards as follows:
getnetbyaddr(): XNS4.0
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 Internet 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 sequentially 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 flag of the netent_data structure if you are not using the setnetent() function.
RETURN VALUES
Upon successful completion, the getnetbyaddr() function and its backward 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 getnetbyaddr() function.
[Tru64 UNIX] If any of the following conditions occurs, the getnetbyaddr_r() function sets errno to the corresponding value:
The net or net_data parameter is invalid. The search failed.
FILES
The DARPA Internet network name database file. Each record in the file occupies a single line and has three fields: the official network
name, the network number, and alias.
RELATED INFORMATION
Functions: endnetent(3), getnetent(3), getnetbyname(3), setnetent(3).
Files: networks(4), svc.conf(4).
Networks: nis_intro(7).
Standards: standards(5) delim off
getnetbyaddr(3)