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getipnodebyaddr(3)
NAME
  getipnodebyaddr - Gets a network host entry by address

LIBRARY
  Standard C Library (libc.so, libc.a)

SYNOPSIS
  #include <netdb.h>

  struct hostent *getipnodebyaddr(
	  const void *src,
	  size_t len,
	  int af,
	  int *error_num);

PARAMETERS
  src	    Specifies an Internet address in network order.

  len	    Specifies the number of bytes in an Internet address.

  af	    Specifies the Internet domain address format.  Valid values are
	    AF_INET and AF_INET6.

  error_num Specifies an error return code value if the function is not
	    successful.	 See the ERRORS section for a description of the
	    values.

DESCRIPTION
  The getipnodebyaddr() routine returns a pointer to a structure of type
  hostent.  Its members specify data obtained from either the local
  /etc/hosts file or one of the files distributed by DNS/BIND or NIS.  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 hostent structure.

  The getipnodebyaddr() routine searches the network host database
  sequentially until a match with the src and af parameters occurs.  The len
  parameter must specify the number of bytes in an Internet address.  The src
  parameter must specify the address in network order.	The af parameter can
  be either the constant AF_INET or AF_INET6, which specifies the Internet
  Protocol Version 4 (IPv4) address format or Internet Protocol Version 6
  (IPv6) address format, respectively.	When EOF (End-of-File) is reached
  without a match, an error value is returned.

  If the src parameter is either an Internet Protocol Version 4 (IPv4) mapped
  IPv6 address or an IPv4-compatible IPv6 address, the routine performs the
  following steps in order:

   1.  If the af parameter is AF_INET6, the len parameter is 16, and the src
       parameter is either an IPV4-mapped IPv6 address or an IPv4-compatible
       IPv6 address, the routine skips the first 12 bytes of the address,
       sets af to AF_INET and len to 4.

   2.  If the af parameter is AF_INET, the routine queries for a PTR record
       in the in-addr.arpa domain.

   3.  If the af parameter is AF_INET6, the routine queries for a PTR record
       in the ip6.int domain.

   4.  If the routine returns success, the single address and address family
       returned in the hostent structure are copies of the src parameter and
       the af parameter, respectively, that were passed to the routine.

				     Note

       The :: and ::1 IPv6 addresses are not considered IPv4-compatible
       addresses.


  If using DNS/BIND, the information is obtained from a name server specified
  in the /etc/resolv.conf file.	 When the name server is not running, the
  getipnodebyaddr() routine searches the local hosts name file.

  The getipnodebyaddr() routine dynamically allocates the hostent structure.
  Use the freehostent() routine to free the allocated memory.

EXAMPLES
   1.  For IPv4 applications (backward compatibility), use the following
       syntax:
	    getipnodebyaddr(address, 4, AF_INET, &error_num);

RETURN VALUES
  Upon successful completion, the getipnodebyaddr() routine returns a pointer
  to a hostent structure.  If it reaches the end of the network hostname
  database, it returns a null pointer.

ERRORS
  If the getipnodebyaddr() routine call fails, error_num is set to one of the
  following values:

  [HOST_NOT_FOUND]
	    Host is unknown.

  [NO_DATA] The server recognized the request and the name, but no address is
	    available for the name.  Another type of name server request may
	    be successful.

  [NO_RECOVERY]
	    An unexpected server failure occurred.  This is a nonrecoverable
	    error.

  [TRY_AGAIN]
	    A transient error occurred, for example, the server did not
	    respond.  A retry at some later time may be successful.

FILES
  /etc/hosts
	    This file is the Internet network hostname database.  Each record
	    in the file occupies a single line and has three fields
	    consisting of the host address, official hostname, and aliases.

  /etc/resolv.conf
	    The resolver configuration file.

  /etc/svc.conf
	    The database service selection configuration file.

RELATED INFORMATION
  Routines: endhostent(3), freehostent(3), getipnodebyname(3), sethostent(3).

  Files: hosts(4), resolv.conf(4), svc.conf(4).

  Networks: bind_intro(7), nis_intro(7).

  Standards: standards(5).

Index for Section 3

Alphabetical listing for G

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