There is no explicit support in IO::Socket::SSL to do this, that is it can only deal with fixed certificates for SNI and has no way to create a certificate on demand for SNI. The way SNI on the server side works is by supplying an tls_ext_servername_callback and set the relevant context there.

I suggest you have a look at the code for IO::Socket::SSL and look how it uses Net::SSLeay::CTX_set_tlsext_servername_callback. Your code must work in a similar way, but instead of using an already created SSL context you have to create a new context with your own certifcates in this callback.

thanks for this!

according to CPAN

http://search.cpan.org/~mikem/Net-SSLeay-1.66/lib/Net/SSLeay.pod#Low_level_API:_Server_side_Server_Name_Indication_%28SNI%29_support

the goal can be reached with code like this:

# create default context
my $ctx = Net::SSLeay::CTX_new or die;
Net::SSLeay::CTX_set_cipher_list($ctx, 'ALL');
Net::SSLeay::set_cert_and_key($ctx, 'cert.pem','key.pem') or die;

# create new context for each new hostname
my %hostnames = ();
Net::SSLeay::CTX_set_tlsext_servername_callback(
    $ctx,
    sub {
        my $ssl = shift;
        my $h = Net::SSLeay::get_servername($ssl);
        unless (exists $hostnames{$h}) {
            $hostnames{$h}->{ctx} = Net::SSLeay::CTX_new or die;
            Net::SSLeay::CTX_set_cipher_list($hostnames{$h}->{ctx}, 'A
+LL');
            $hostnames{$h}->{cert} = ... # generate certificate and
            $hostnames{$h}->{key}  = ... # key based on hostname in $h
                                         # and re-use them in future f
+rom hash as below
            Net::SSLeay::set_cert_and_key(
                $hostnames{$h}->{ctx},
                $hostnames{$h}->{cert},
                $hostnames{$h}->{key}
            ) or die;
        }
        Net::SSLeay::set_SSL_CTX($ssl, $hostnames{$h}->{ctx});
    }
);
[download]

but every new cert/key pair generation will use some time.
in my case, the script is a multiplexing server based on IO::Select, so it reads and writes with short parts of data to prevent any long/heavy transfer to block the others.
and each time the new pair is generated the script will block for this time.

is there a way to solve this in non-blocking manner?

thanks!

> is there a way to solve this in non-blocking manner?

I don't think so. To do this in a sensible non-blocking way you would need to have control about the SSL state machine. But OpenSSL only exposes some hooks into this machine with callbacks and I don't think you can have multiple servername callbacks on the same context run in parallel.