INTERNET(3X) INTERNET(3X)
NAME
in_host, in_ntoa, in_address, in_service - internet
networking functions
SYNOPSIS
#include <sys/inet/in.h>
char *in_host(hostaddr)
in_addr hostaddr;
char *in_ntoa(hostaddr)
in_addr hostaddr;
in_addr in_address(hostname)
char *hostname;
struct in_service *in_service(name, proto, port)
char *name, *proto;
unsigned long port;
DESCRIPTION
These routines are loaded by the -lin option of ld(1).
Internet addresses, type in_addr, are 32-bit quantities glo-
bal to the network. The ASCII representation of an in_addr
can be either a host name or of the form b1.b2.b3.b4, where
each `bx' is the value of the x'th byte of the address in
decimal. Since host names are considered local `aliases'
for internet addresses, the host-to-address mapping is sub-
jective.
In_address maps an internet host name to an address and
returns 0 if the name is not found in the host table.
In_host maps an internet address into a host name. If the
host is not found in the host table, the ASCII representa-
tion of the address is returned.
In_ntoa maps an internet address to its ASCII numeric for-
mat.
In_service returns the closest match to name in the services
file. If either name or port are 0, they will match any
name or port. If proto is (char *)0, the tcp protocol is
assumed.
FILES
/usr/inet/lib/hosts mapping between host names and addresses
/usr/inet/lib/networks mapping between network names and addresses
/usr/inet/lib/services database of services
INTERNET(3X) INTERNET(3X)
/usr/inet/lib/hosts.equiv machines with common administration
SEE ALSO
ipc(3), tcp(3), udp(3)
BUGS
The mappings between internet addresses and names is arbi-
trary at best. The hosts file may contain many addresses
for each name and/or many names for each address.
In_address and in_host each start at the beginning of the
file and search sequentially for a match. Therefore,
in_addr(in_host(addr)) == addr is not necessarily true.