getipnodebyaddr - Get a network host entry by address
struct hostent *getipnodebyaddr(
const void *src,
int *error_num );
Standard C Library (libc)
Specifies an Internet address in network order. Specifies
the number of bytes in an Internet address. Specifies the
Internet domain address format. Valid values are AF_INET
and AF_INET6. Specifies an error return code value if the
function is not successful. See the ERRORS section for a
description of the values.
The use of this routine is deprecated. Use the getnameinfo(3) routine instead; it is also protocol-independent.
The getipnodebyaddr() routine is an evolution of the gethostbyaddr()
routine that enables address lookups in
address families other than AF_INET.
The getipnodebyaddr() routine returns a pointer to a
structure of type hostent. Its members specify data
obtained from the local /etc/ipnodes file, /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: 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. If the af parameter is AF_INET, the
routine queries for a PTR record in the in-addr.arpa
domain. If the af parameter is AF_INET6, the routine
queries for a PTR record in the ip6.int domain. 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.
The :: and ::1 IPv6 addresses are not considered IPv4-compatible
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 ipnodes name file for IPv6 and IPv4
addresses and the hosts name file for IPv4 addresses, if
none are found in the ipnodes file.
The getipnodebyaddr() routine dynamically allocates the
hostent structure. Use the freehostent() routine to free
the allocated memory.
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
If the getipnodebyaddr() routine call fails, error_num is
set to one of the following values: Host is unknown. 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. An unexpected server failure
occurred. This is a nonrecoverable error. A transient
error occurred, for example, the server did not respond.
A retry at some later time may be successful.
For IPv4 applications (backward compatibility), use the
getipnodebyaddr(address, 4, AF_INET, &error_num);
The Internet network node name database. Each record in
the file occupies a single line and has three fields consisting
of the node address (IPv6 or IPv4), official node
name, and aliases. 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
IPv4 address, official hostname, and aliases. The
resolver configuration file. The database service selection
Routines: endhostent(3), freehostent(3), getnameinfo(3),
Files: hosts(4), resolv.conf(4), svc.conf(4).
Networks: bind_intro(7), nis_intro(7).
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