Socket(3) Perl Programmers Reference Guide Socket(3)NAME
Socket, sockaddr_in, sockaddr_un, inet_aton, inet_ntoa -
load the C socket.h defines and structure manipulators
SYNOPSIS
use Socket;
$proto = getprotobyname('udp');
socket(Socket_Handle, PF_INET, SOCK_DGRAM, $proto);
$iaddr = gethostbyname('hishost.com');
$port = getservbyname('time', 'udp');
$sin = sockaddr_in($port, $iaddr);
send(Socket_Handle, 0, 0, $sin);
$proto = getprotobyname('tcp');
socket(Socket_Handle, PF_INET, SOCK_STREAM, $proto);
$port = getservbyname('smtp', 'tcp');
$sin = sockaddr_in($port,inet_aton("127.1"));
$sin = sockaddr_in(7,inet_aton("localhost"));
$sin = sockaddr_in(7,INADDR_LOOPBACK);
connect(Socket_Handle,$sin);
($port, $iaddr) = sockaddr_in(getpeername(Socket_Handle));
$peer_host = gethostbyaddr($iaddr, AF_INET);
$peer_addr = inet_ntoa($iaddr);
$proto = getprotobyname('tcp');
socket(Socket_Handle, PF_UNIX, SOCK_STREAM, $proto);
unlink('/tmp/usock');
$sun = sockaddr_un('/tmp/usock');
connect(Socket_Handle,$sun);
DESCRIPTION
This module is just a translation of the C socket.h file.
Unlike the old mechanism of requiring a translated
socket.ph file, this uses the h2xs program (see the Perl
source distribution) and your native C compiler. This
means that it has a far more likely chance of getting the
numbers right. This includes all of the commonly used
pound-defines like AF_INET, SOCK_STREAM, etc.
Also, some common socket "newline" constants are provided:
the constants "CR", "LF", and "CRLF", as well as "$CR",
"$LF", and "$CRLF", which map to "\015", "\012", and
"\015\012". If you do not want to use the literal charac
ters in your programs, then use the constants provided
here. They are not exported by default, but can be
imported individually, and with the ":crlf" export tag:
use Socket qw(:DEFAULT :crlf);
In addition, some structure manipulation functions are
available:
inet_aton HOSTNAME
Takes a string giving the name of a host, and trans
lates that to the 4-byte string (structure). Takes
arguments of both the 'rtfm.mit.edu' type and
'18.181.0.24'. If the host name cannot be resolved,
returns undef. For multi-homed hosts (hosts with more
than one address), the first address found is
returned.
inet_ntoa IP_ADDRESS
Takes a four byte ip address (as returned by
inet_aton()) and translates it into a string of the
form 'd.d.d.d' where the 'd's are numbers less than
256 (the normal readable four dotted number notation
for internet addresses).
INADDR_ANY
Note: does not return a number, but a packed string.
Returns the 4-byte wildcard ip address which specifies
any of the hosts ip addresses. (A particular machine
can have more than one ip address, each address corre
sponding to a particular network interface. This wild
card address allows you to bind to all of them simul
taneously.) Normally equivalent to
inet_aton('0.0.0.0').
INADDR_BROADCAST
Note: does not return a number, but a packed string.
Returns the 4-byte 'this-lan' ip broadcast address.
This can be useful for some protocols to solicit
information from all servers on the same LAN cable.
Normally equivalent to inet_aton('255.255.255.255').
INADDR_LOOPBACK
Note - does not return a number.
Returns the 4-byte loopback address. Normally equiva
lent to inet_aton('localhost').
INADDR_NONE
Note - does not return a number.
Returns the 4-byte 'invalid' ip address. Normally
equivalent to inet_aton('255.255.255.255').
sockaddr_in PORT, ADDRESS
sockaddr_in SOCKADDR_IN
In a list context, unpacks its SOCKADDR_IN argument
and returns an array consisting of (PORT, ADDRESS).
In a scalar context, packs its (PORT, ADDRESS) argu
ments as a SOCKADDR_IN and returns it. If this is
confusing, use pack_sockaddr_in() and unpack_sock_
addr_in() explicitly.
pack_sockaddr_in PORT, IP_ADDRESS
Takes two arguments, a port number and a 4 byte
IP_ADDRESS (as returned by inet_aton()). Returns the
sockaddr_in structure with those arguments packed in
with AF_INET filled in. For internet domain sockets,
this structure is normally what you need for the argu
ments in bind(), connect(), and send(), and is also
returned by getpeername(), getsockname() and recv().
unpack_sockaddr_in SOCKADDR_IN
Takes a sockaddr_in structure (as returned by
pack_sockaddr_in()) and returns an array of two ele
ments: the port and the 4-byte ip-address. Will croak
if the structure does not have AF_INET in the right
place.
sockaddr_un PATHNAME
sockaddr_un SOCKADDR_UN
In a list context, unpacks its SOCKADDR_UN argument
and returns an array consisting of (PATHNAME). In a
scalar context, packs its PATHNAME arguments as a
SOCKADDR_UN and returns it. If this is confusing, use
pack_sockaddr_un() and unpack_sockaddr_un() explic
itly. These are only supported if your system has
<sys/un.h>.
pack_sockaddr_un PATH
Takes one argument, a pathname. Returns the sock
addr_un structure with that path packed in with
AF_UNIX filled in. For unix domain sockets, this
structure is normally what you need for the arguments
in bind(), connect(), and send(), and is also returned
by getpeername(), getsockname() and recv().
unpack_sockaddr_un SOCKADDR_UN
Takes a sockaddr_un structure (as returned by
pack_sockaddr_un()) and returns the pathname. Will
croak if the structure does not have AF_UNIX in the
right place.
2001-03-18 perl v5.6.1 Socket(3)
