Index for Section 3

Alphabetical listing for G

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);

  [Digital]  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);

  [Digital]  The following definition of the getnetbyaddr() function does not
  conform to current standards and is supported only for backward
  compatibility:

  struct netent *getnetbyaddr(
	  int num,
	  int type);

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  getnetbyaddr():  XPG4-UNIX

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  num	    Specifies the number of the network in host-byte order.

  net	    [Digital]  For getnetbyaddr_r(), this points to the netent
	    structure.	The netdb.h header file defines the netent structure.

  type	    Specifies the Internet domain address format. The value AF_INET
	    must be used.

  num	    [Digital]  Specifies the number of the network in host-byte
	    order.

  net_data  [Digital]  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.

  [Digital]  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.

  [Digital]  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.

  [Digital]  If any of the following conditions occurs, the getnetbyaddr_r()
  function sets errno to the corresponding value:

  [EINVAL]  The net or net_data parameter is invalid.

  [ESRCH]   The search failed.

FILES
  /etc/networks
	    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)