7.2.58 Socket - Load the C socket.h Defines and Structure Manipulators

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);

socket(Socket_Handle, PF_UNIX, SOCK_STREAM, 0);
unlink('/tmp/usock');
$sun = sockaddr_un('/tmp/usock');
bind(Socket_Handle, $sun);

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 preprocessor-defined constants like AF_INET , SOCK_STREAM , and so on.

In addition, some structure manipulation functions are available:

inet_aton HOSTNAME

Takes a string giving the name of a host, and translates that to a four-byte, packed string (structure). Takes arguments of both the rtfm.mit.edu and 18.181.0.24 types. If the host name cannot be resolved, returns the undefined value.

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, dotted-quad notation for Internet addresses).

INADDR_ANY

Note: This function does not return a number, but a packed string. Returns the four-byte wildcard IP address that specifies any of the host's 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 simultaneously.) Normally equivalent to inet_aton('0.0.0.0') .

INADDR_LOOPBACK

Note: does not return a number, but a packed string. Returns the four-byte loopback address. Normally equivalent to inet_aton('localhost') .

INADDR_NONE

Note: does not return a number, but a packed string. Returns the four-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 a list 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 a four-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 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 a list of two elements: the port and the four-byte IP address. This function 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, it unpacks its SOCKADDR_UN argument and returns a list consisting of ( PATHNAME ) . In a scalar context, it packs its PATHNAME argument as a SOCKADDR_UN and returns it. If this is confusing, use pack_sockaddr_un() and unpack_sockaddr_un() explicitly. These functions 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 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.