Socket
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('/var/run/usock');
$sun = sockaddr_un('/var/run/usock');
connect(Socket_Handle,$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 com-
piler. 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 con-
stants "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 programs, then use the constants provided
here. They are not exported by default, but can be imported individu-
ally, 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 net-
work 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.
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
getpeername()) and returns the address family tag. It will match
the constant AF_INET for a sockaddr_in and AF_UNIX for a sock-
addr_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() explic-
itly. 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 v5.8.6 2001-09-21 Socket(3)
