avoid ssl_eof error on SSL_WANT_READ and friends

lib/DJabberd/Stanza/StartTLS.pm

 package DJabberd::Stanza::StartTLS;
 use strict;
 use base qw(DJabberd::Stanza);
 use Net::SSLeay;
 
 Net::SSLeay::load_error_strings();
 Net::SSLeay::SSLeay_add_ssl_algorithms();
 Net::SSLeay::randomize();
 
 use constant SSL_ERROR_WANT_READ     => 2;
 use constant SSL_ERROR_WANT_WRITE    => 3;
+use constant SSL_ERROR_WANT_CONNECT  => 4;
+use constant SSL_ERROR_WANT_ACCEPT   => 5;
 
 sub on_recv_from_server { &process }
 sub on_recv_from_client { &process }
 
 sub process {
     my ($self, $conn) = @_;
 
     # {=tls-no-spaces} -- we can't send spaces after the closing bracket
     $conn->write("<proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls' />");
 
@@ skipping 37 matching lines @@
     if (!$rv) {
         warn "SSL accept error on $conn\n";
         $conn->close;
         return;
     }
 
     warn "$conn:  Cipher `" . Net::SSLeay::get_cipher($ssl) . "'\n";
 
     $conn->set_writer_func(DJabberd::Stanza::StartTLS->danga_socket_writerfunc($conn));
 }
+
+sub actual_error_on_empty_read {
+    my ($class, $ssl) = @_;
+    my $err = Net::SSLeay::get_error($ssl, -1);
+    if ($err == SSL_ERROR_WANT_READ || 
+        $err == SSL_ERROR_WANT_WRITE || 
+        $err == SSL_ERROR_WANT_CONNECT || 
+        $err == SSL_ERROR_WANT_ACCEPT) {
+        # Not an actual error, SSL is busy doing something like renegotiating encryption
+        # just try again next time
+        return 0;
+    }
+    # This is actually an error (return the SSL err code)
+    # unlike the 'no-op' WANT_READ and WANT_WRITE
+    return $err;
+}
+
 
 sub danga_socket_writerfunc {
     my ($class, $conn) = @_;
     my $ssl = $conn->{ssl};
     return sub {
         my ($bref, $to_write, $offset) = @_;
 
         # unless our event_read has been called, we don't want to try
         # to do any work now.  and probably we should complain.
         if ($conn->{write_when_readable}) {
@@ skipping 28 matching lines @@
             return 0;
         }
 
         return $written;
     };
 }
 
 1;
 
 #  LocalWords:  conn