Socket(3p) Perl Programmers Reference Guide Socket(3p)
Socket, sockaddr_in, sockaddr_un, inet_aton, inet_ntoa -
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', '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('/var/run/usock');
$sun = sockaddr_un('/var/run/usock');
connect(Socket_Handle,$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 dis-
tribution) 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 characters in your pro-
grams, 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);
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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 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.
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
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 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.
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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 buil-
tin functions getsockname() and getpeername()) and
returns the address family tag. It will match the con-
stant 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 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 an array of two ele-
ments: 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(),
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and send(), and is also returned by getpeername(), get-
sockname() 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.
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