MAN page from RedHat Other perl-5.004-0.1.i386.rpm

Socket

Section: Perl Programmers Reference Guide (3)
Updated: perl 5.004, patch 04
Index

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');    $sin = sockaddr_in($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.phfile, 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 includesall of the commonly used pound-defines like AF_INET, SOCK_STREAM, etc.

In addition, some structure manipulation functions are available:

inet_aton HOSTNAME

Takes a string giving the name of a host, and translates thatto the 4-byte string (structure). Takes arguments of boththe `rtfm.mit.edu' type and `18.181.0.24'. If the host namecannot be resolved, returns undef. For multi-homed hosts (hostswith 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 normalreadable 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 anyof the hosts ip addresses. (A particular machine can havemore than one ip address, each address corresponding toa particular network interface. This wildcard addressallows you to bind to all of them simultaneously.)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 informationfrom 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 equivalentto inet_aton('localhost').

INADDR_NONE

Note - does not return a number.

Returns the 4-byte `invalid' ip address. Normally equivalentto inet_aton('255.255.255.255').

sockaddr_in PORT, ADDRESS

sockaddr_in SOCKADDR_IN

In an array context, unpacks its SOCKADDR_IN argument and returns an arrayconsisting of (PORT, ADDRESS). In a scalar context, packs its (PORT,ADDRESS) arguments as a SOCKADDR_IN and returns it. If this is confusing,use pack_sockaddr_in() and unpack_sockaddr_in() explicitly.

pack_sockaddr_in PORT, IP_ADDRESS

Takes two arguments, a port number and a 4 byte IP_ADDRESS (as returned byinet_aton()). Returns the sockaddr_in structure with those argumentspacked in with AF_INET filled in. For internet domain sockets, thisstructure is normally what you need for the arguments 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()) andreturns an array of two elements: 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 an array context, unpacks its SOCKADDR_UN argument and returns an arrayconsisting of (PATHNAME). In a scalar context, packs its PATHNAMEarguments as a SOCKADDR_UN and returns it. If this is confusing, usepack_sockaddr_un() and unpack_sockaddr_un() explicitly.These are only supported if your system has <sys/un.h>.

pack_sockaddr_un PATH

Takes one argument, a pathname. Returns the sockaddr_un structure withthat path packed in with AF_UNIX filled in. For unix domain sockets, thisstructure 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 nothave AF_UNIX in the right place.

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