getnetent() — Get the next network entry

Standards

Standards / Extensions C or C++ Dependencies

XPG4.2
Single UNIX Specification, Version 3

 both  

Format

X/Open: 
#define _XOPEN_SOURCE_EXTENDED 1
#include <netdb.h>

struct netent *getnetent(void);
Berkeley sockets: 
#define _OE_SOCKETS
#include <netdb.h>

struct netent *getnetent(void);

General description

The getnetent() call reads the next entry of the tcpip.HOSTS.ADDRINFO data set.

You can use the X_ADDR environment variable to specify a data set other than tcpip.HOSTS.ADDRINFO.

Note: For more information on these data sets and environment variables, tcpip.HOSTS.LOCAL, tcpip.HOSTS.ADDRINFO, and tcpip.HOSTS.SITEINFO, see z/OS V2R1.0 Communications Server: IP Configuration Guide.

The getnetent() call returns a pointer to the next entry in the tcpip.HOSTS.SITEINFO data set.

getnetbyaddr(), getnetbyname(), and getnetent() all use the same static area to return the netent structure. This static area is only valid until the next one of these functions is called on the same thread.

The netent structure is defined in the netdb.h include file and contains the following elements:
Element
Description
n_addrtype
The type of network address returned. The call always sets this value to AF_INET.
n_aliases
An array, terminated with a NULL pointer, of alternative names for the network.
n_name
The official name of the network.
n_net
The network number, returned in host byte order.

Special behavior for C++: To use this function with C++, you must use the _XOPEN_SOURCE_EXTENDED 1 feature test macro.

Returned value

If successful, getnetent() returns a pointer to a netent structure. The return value points to data that is overwritten by subsequent calls returning the same data structure.

If unsuccessful, getnetent() returns a NULL pointer, indicating an error or End Of File (EOF).

Related information

Parent topic: Library functions