Socket Programming With Perl
Sample client
#!/usr/bin/perl -w
use strict;
use Socket;
my ($remote,$port, $iaddr, $paddr, $proto, $line);
$remote = 'localhost';
$port = 2345;
$iaddr = inet_aton($remote) || die "no host: $remote";
$paddr = sockaddr_in($port, $iaddr);
$proto = getprotobyname('tcp');
socket(SOCK, PF_INET, SOCK_STREAM, $proto) || die "socket: $!";
connect(SOCK, $paddr) || die "connect: $!";
while (defined($line = <SOCK>)) {
print $line;
}
close (SOCK) || die "close: $!";
Sample server
#!/usr/bin/perl -Tw
use strict;
use Socket;
use Carp;
use POSIX ":sys_wait_h";
use Errno;
my $EOL = "\015\012";
my $port = 2345;
my $proto = getprotobyname('tcp');
my $waitedpid = 0;
my $paddr;
sub spawn; # forward declaration
sub logmsg { print "$0 $$: @_ at ", scalar localtime, "\n" }
sub REAPER {
local $!; # don't let waitpid() overwrite current error
while ((my $pid = waitpid(-1,WNOHANG)) > 0 && WIFEXITED($?)) {
logmsg "reaped $waitedpid" . ($? ? " with exit $?" : '');
}
$SIG{CHLD} = \&REAPER; # loathe sysV
}
$SIG{CHLD} = \&REAPER;
socket(SERVER, PF_INET, SOCK_STREAM, $proto) || die "socket: $!";
setsockopt(SERVER, SOL_SOCKET, SO_REUSEADDR, pack("l", 1)) || die "setsockopt: $!";
bind(SERVER, sockaddr_in($port, INADDR_ANY)) || die "bind: $!";
listen(SERVER,SOMAXCONN) || die "listen: $!";
while(1) {
$paddr = accept(CLIENT, SERVER) || do {
# try again if accept() returned because a signal was received
next if $!{EINTR};
die "accept: $!";
};
my ($port, $iaddr) = sockaddr_in($paddr);
my $name = gethostbyaddr($iaddr, AF_INET);
logmsg "connection from $name [", inet_ntoa($iaddr), "] at port $port";
spawn sub {
$|=1;
print "Hello there, $name, it's now ", scalar localtime, $EOL;
exec '/usr/games/fortune' or confess "can't exec fortune: $!";
};
close Client;
}
sub spawn {
my $coderef = shift;
unless (@_ == 0 && $coderef && ref($coderef) eq 'CODE') {
confess "usage: spawn CODEREF";
}
my $pid;
if (! defined($pid = fork)) {
logmsg "cannot fork: $!";
return;
} elsif ($pid) {
logmsg "begat $pid";
return; # I'm the parent
}
# else I'm the child -- go spawn
open(STDIN, "<&Client") || die "can't dup client to stdin";
open(STDOUT, ">&Client") || die "can't dup client to stdout";
## open(STDERR, ">&STDOUT") || die "can't dup stdout to stderr";
exit &$coderef();
}
Another example:
#!/usr/bin/perl
# maillog.serve
use Socket;
$port = "2680";
$remote = "someIP";
$proto = getprotobyname('tcp');
socket(SOCK, PF_INET, SOCK_STREAM, $proto);
setsockopt(SOCK, SOL_SOCKET, SO_REUSEADDR, pack("l",1)); // the first parameter to the pack method is the lower-cased letter L
$iaddr = inet_aton($remote);
$paddr = sockaddr_in($port, $paddr); // Should the second parameter to sockaddr_in be iaddr?
bind(SOCK, paddr);
listen(SOCK, SOMAXCONN);
for (; $paddr = accept(CLIENT, SOCK); close(CLIENT)) {
print CLIENT $_;
}
Other information:
use Socket;
use IO::Socket;
$socket = IO::Socket::INET->new(
PeerAddr => 'www.perl.org',
PeerPort => 'http(80)',
Proto => 'tcp'
);
$sock = IO::Socket::INET->new(
PeerAddr => 'localhost:smtp(25)'
);
$sock = IO::Socket::INET->new(
Listen => 25,
LocalAddr => 'localhost',
LocalPort => 9000,
Proto => 'tcp'
);
sockport() // returns the port number on the local host
sockhost() // returns the IP of the local socket
peerport() // returns the port number of the remote host
peerhost() // returns the IP of the remote host
timeout([val])
sockopt(OPT [,VAL])
sockdomain() // returns the numerical number for socket domain
// For a AF_INET, the value will be &AF_INET
socktype() // returns the numerical number for socket type
// For a SOCK_STREAM socket, the value &SOCK_STREAM is returned
inet_aton HOSTNAME // Takes a hostname or an IP address and
// converts it to numeric form (structure) sockaddr_in
inet_ntoa IP_ADDR // Takes a numeric form (structure) (returned by inet_aton)
// and converts it to dotted IP address.
INADDR_ANY
INADDR_BROADCAST
INADDR_LOOPBACK
INADDR_NONE // represent invalid IP address.
sockaddr_in(PORT, ADDRESS) // pack and return a sockaddr_in structure
sockaddr_in(SOCKADDR_IN) // unpack and return a list (port, address)
$proto = getprotobyname('udp'); // returns the protocol number for given protocol
$iaddr = gethostbyname('xyz.com'); // returns the internal address for given hostname/IP.
$port = getservbyname('time','udp'); // returns the port number for given service and protocol
$peer_host = gethostbyaddr($iaddr, AF_INET);
$peer_addr = inet_ntoa($iaddr);
($port,$iaddr) = sockaddr_in(getpeername(socketHandle));
socket(SOCKFD, DOMAIN, TYPE, PROTOCOL);
connect(SOCKFD, NAME); // NAME should be a packed address of appropriate type
listen(SOCKFD, QUEUESIZE);
accept(NEWSOCK,GENERICSOCK);
send(SOCKFD, MSG, FLAGS)
page revision: 8, last edited: 13 Apr 2016 10:42