Non-blocking IO::Socket::SSL client example

use IO::Socket::INET;
use IO::Socket::SSL;
use IO::Select;
use strict;

my $sock = IO::Socket::INET->new(
  PeerHost => 'encrypted.google.com', PeerPort => 443, Blocking => 0
) or die $@; # first create simple N-B socket with IO::Socket::INET

my $sel = IO::Select->new($sock); # wait until it connected
if ($sel->can_write) {
    print "IO::Socket::INET connected\n";
}

# upgrade socket to IO::Socket::SSL
IO::Socket::SSL->start_SSL($sock, SSL_startHandshake => 0);

# make non-blocking SSL handshake
while (1) {
    if ($sock->connect_SSL) { # will not block
        print "IO::Socket::SSL connected\n";
        last;
    }
    else { # handshake still incomplete
        print "IO::Socket::SSL not connected yet\n";
        if ($SSL_ERROR == SSL_WANT_READ) {
            $sel->can_read;
        }
        elsif ($SSL_ERROR == SSL_WANT_WRITE) {
            $sel->can_write;
        }
        else {
            die "IO::Socket::SSL unknown error: ", $SSL_ERROR;
        }
    }
}

# sucessfully connected, we can write to socket
$sock->syswrite(
    join(
        "\015\012",
        "GET / HTTP/1.0",
        "\015\012"
    )
) or die $!;

# and then read from it
while ($sel->can_read && $sock->sysread(my $buf, 1024)) {
    print $buf;
}

$sock->close();