[squid-dev] Piping existing SSL session into squid SSL session cache

Alex Rousskov rousskov at measurement-factory.com
Wed Apr 27 21:06:15 UTC 2016

On 04/27/2016 01:01 PM, Florian Schüttler wrote:

> I have a scenario in which clients (<10) are connected to a server using
> an application protocol inside a TLS connection. These clients should
> now be able to reuse the existing TLS session for a TLS connection to
> Squid running on the same server by passing the session (e.g. using two
> OpenSSL s_client instances and parameter -sess_out resp. -sess_in). That
> would save an expensive key exchange operation. So far, my application
> server writes the session info to a named pipe when the handshake is
> completed using OpenSSL's PEM_write_SSL_SESSION().

Just to clarify: Do you want the client-to-Squid TLS connection to reuse
a TLS session established when the client was talking to an application
server that has nothing to do with Squid/HTTP except that both Squid and
the application server run on the same box?

> I would now like to implement a feature in Squid which periodically
> reads the pipe and adds this session information to the staticSslContext
> in Squid using PEM_read_SSL_SESSION(). Ideally, this would integrate
> into the event scheduling infrastructure (commEngine?) and not just be
> hacked into the main loop, but I can not find easy documentation about
> how to achieve this. Can anyone give me some pointers?

AFAIK, there is no "easy documentation" for what you want to do.

If possible, I would simplify this a lot by writing session information
into a well-known file and [re]loading the session information [if it
has changed] just after accepting a TCP connection on https_port and
before calling SSL_accept(). This way, there is no need to add any new
Squid "events" and maintain an asynchronous session-updating job
reacting to those events.



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