use warnings;
use strict;

use IO::Socket::SSL;

use constant { BUFSIZE => 16384 };
die 'Invalid BUFSIZE value (must be a multiple of 16)' if(BUFSIZE%16);

my $LOCAL_ADDR='0.0.0.0';
my $LOCAL_PORT=1234;
my $BUFFER = '0123456789ABCDEF' x (BUFSIZE/16);

my $srvSock;
$srvSock=IO::Socket::SSL->new(
  LocalHost => $LOCAL_ADDR,
  LocalPort => $LOCAL_PORT,
  ReuseAddr => 1,
  Listen => 1,
  SSL_cert_file => 'cert.pem',
  SSL_key_file => 'key.pem',
) or die "Failed to create listening SSL socket: $!";

print "SSL server listening on $LOCAL_ADDR:$LOCAL_PORT\n";

while() {
  print "Waiting for client to connect...\n";
  my $clientSock = $srvSock->accept()
    or die "Failed to accept SSL client connection: $!, $SSL_ERROR\n";

  print "Client connected, sending data.\n";
  while() {
    my $writeLength=syswrite($clientSock,$BUFFER)
      or do {
        print "  Failed to write to client: $!, $SSL_ERROR\n";
        last;
      };
    if($writeLength != BUFSIZE) {
      print "  Unexpected write length: $writeLength\n";
      last;
    }
  }
}
##</code><code>##

use warnings;
use strict;

use IO::Socket::SSL;
use Time::HiRes qw'time';

use constant { 
  BUFSIZE => 16384,
  INTERVAL => 1,
};

my $PEER_ADDR='192.168.1.10';
my $PEER_PORT=1234;

print "Connecting to SSL server ($PEER_ADDR:$PEER_PORT)\n";
my $clientSock = IO::Socket::SSL->new(
  PeerHost => $PEER_ADDR,
  PeerPort => $PEER_PORT,
  Proto => 'tcp',
  SSL_verify_mode => SSL_VERIFY_NONE,
) or die "Failed to connect to SSL server: $!, $SSL_ERROR";

print "Connected, switching to non-blocking mode.\n";
$clientSock->blocking(0);

my $sockVec='';
vec($sockVec,fileno($clientSock),1)=1;

my ($nbRead,$nbSslWantRead,$nbSslWantWrite,$transferred)=(0,0,0,0);

print "Downloading data from server...\n";
my $currentTime=time();
my ($intvlStart,$intvlEnd)=($currentTime,$currentTime+INTERVAL);
while() {

  # There should be no pending data when BUFSIZE = max SSL frame size
  die 'Unexpected pending data in SSL socket'
      if($clientSock->pending());
  
  $!=0;
  select(my $readyVec=$sockVec,undef,undef,undef) > 0
      or die "Error in select for read: $!";
  
  my $readLength=sysread($clientSock,my $readData,BUFSIZE);
  $nbRead++;
  if(defined $readLength) {
    die "Connection closed by peer"
        unless($readLength);
    die "Unexpected read length: $readLength"
        unless($readLength == BUFSIZE);
  }else{
    die "Failed to read from SSL socket: $!"
        unless($!{EWOULDBLOCK} || $!{EAGAIN});
    if($SSL_ERROR == SSL_WANT_READ) {
      $nbSslWantRead++;
      next;
    }
    if($SSL_ERROR == SSL_WANT_WRITE) {
      $nbSslWantWrite++;
      select(undef,my $readyVec=$sockVec,undef,undef) > 0
          or die "Error in select for write: $!";
      next;
    }
    die 'Unexpected WOULDBLOCK/EAGAIN status when trying to read';
  }
  
  $transferred+=BUFSIZE;
  $currentTime=time(); 
  if($currentTime >= $intvlEnd) {
    printReport();
    initNewInterval();
  }
}

sub printReport {
  my $speed=formatSize($transferred/($currentTime-$intvlStart));
  my $pctSslWantRead=sprintf('%.2f',$nbSslWantRead*100/$nbRead);
  my $pctSslWantWrite=sprintf('%.2f',$nbSslWantWrite*100/$nbRead);
  print "Transfer speed: $speed/s\n";
  print "  Read failure due to SSL_WANT_READ: $pctSslWantRead%\n";
  print "  Read failure due to SSL_WANT_WRITE: $pctSslWantWrite%\n";
}

sub formatSize {
  my $size=shift;
  my @UNITS=('',qw'K M G T');
  my $unitIdx=0;
  while($size >= 1000 && $unitIdx < $#UNITS) {
    $size/=1000;
    $unitIdx++;
  }
  $size=sprintf('%.2f',$size) if(index($size,'.') != -1);
  return $size.' '.$UNITS[$unitIdx].'B';
}

sub initNewInterval {
  ($nbRead,$nbSslWantRead,$nbSslWantWrite,$transferred)=(0,0,0,0);
  $intvlStart=$currentTime;
  $intvlEnd+=INTERVAL while($intvlEnd < $intvlStart+INTERVAL/2);
}

##</code><code>##

$ perl sslclinb.pl
Connecting to SSL server (192.168.1.10:1234)
Connected, switching to non-blocking mode.
Downloading data from server...
Transfer speed: 117.55 MB/s
  Read failure due to SSL_WANT_READ: 87.46%
  Read failure due to SSL_WANT_WRITE: 0.00%
Transfer speed: 117.61 MB/s
  Read failure due to SSL_WANT_READ: 90.84%
  Read failure due to SSL_WANT_WRITE: 0.00%
Transfer speed: 117.61 MB/s
  Read failure due to SSL_WANT_READ: 90.84%
  Read failure due to SSL_WANT_WRITE: 0.00%
Transfer speed: 117.61 MB/s
  Read failure due to SSL_WANT_READ: 90.88%
  Read failure due to SSL_WANT_WRITE: 0.00%
Transfer speed: 117.61 MB/s
  Read failure due to SSL_WANT_READ: 90.50%
  Read failure due to SSL_WANT_WRITE: 0.00%
Transfer speed: 117.61 MB/s
  Read failure due to SSL_WANT_READ: 82.52%
  Read failure due to SSL_WANT_WRITE: 0.00%
Transfer speed: 117.61 MB/s
  Read failure due to SSL_WANT_READ: 82.63%
  Read failure due to SSL_WANT_WRITE: 0.00%
Transfer speed: 117.61 MB/s
  Read failure due to SSL_WANT_READ: 82.58%
  Read failure due to SSL_WANT_WRITE: 0.00%
Transfer speed: 117.61 MB/s
  Read failure due to SSL_WANT_READ: 82.58%
  Read failure due to SSL_WANT_WRITE: 0.00%
Transfer speed: 117.61 MB/s
  Read failure due to SSL_WANT_READ: 82.57%
  Read failure due to SSL_WANT_WRITE: 0.00%
^C