redhat man page for socket

Socket(3pm)						 Perl Programmers Reference Guide					       Socket(3pm)

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 "15", "12", and "1512".  If you do not want to use the literal characters 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 translates that to an opaque string (if programming in C, struct in_addr). Takes argu-
	   ments 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.

	   For portability do not assume that the result of inet_aton() is 32 bits wide, in other words, that it would contain only the IPv4
	   address in network order.

       inet_ntoa IP_ADDRESS
	   Takes a string (an opaque string as returned by inet_aton(), or a v-string representing the four octets of the IPv4 address in network
	   order) and translates it into a string of the form 'd.d.d.d' where the 'd's are numbers less than 256 (the normal human-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 corresponding to a particular network interface. This wildcard address allows you to bind to all of them simulta-
	   neously.)  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 equivalent 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_family SOCKADDR
	   Takes a sockaddr structure (as returned by pack_sockaddr_in(), pack_sockaddr_un() or the perl builtin functions getsockname() and get-
	   peername()) and returns the address family tag.  It will match the constant AF_INET for a sockaddr_in and AF_UNIX for a sockaddr_un.
	   It can be used to figure out what unpacker to use for a sockaddr of unknown type.

       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) 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 an opaque string, IP_ADDRESS (as returned by inet_aton(), or a v-string).  Returns the sock-
	   addr_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 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()) and returns an array of two elements: the port and an opaque string
	   representing the IP address (you can use inet_ntoa() to convert the address to the four-dotted numeric format).  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() 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 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 getpeer-
	   name(), 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.

perl v5.8.0							    2002-06-01							       Socket(3pm)