[Ovmsdev] Update WolfSSH/SSL

[Mark Webb-Johnson]

The disk space requirement is not really a problem.

The stack size increase is not good, but probably manageable.

Imho, IRAM is out biggest issue at the moment, and any reduction in that is welcome.

Regards, Mark.

> On 24 Jan 2021, at 2:38 PM, Stephen Casner <casner at acm.org> wrote:
> 
> After a pause of three years, I have finally gotten around to updating
> wolfssh and wolfssl to the current stable releases, 1.4.5 and 4.6.0
> respectively.  This includes the code to support SCP that I wrote and
> contributed back to them and was integrated into wolfssh 1.3.0.  There
> were some API tweaks that I needed to work through, but the source
> files are now unmodified except for wolfcrypt/settings.h where I ran
> into a compilation conflict on the XREALLOC macro.  As before, I need
> to supply my own malloc, free and realloc functions so we can control
> PSRAM usage and so we can emit a log message if memory allocation
> fails.
> 
> For starters, this update removes the restriction to use cipher
> aes128-cbc.  In addition, the WolfSSL code now includes integration
> with the hardware crypto acceleration capabilities of the ESP32.  I'm
> not sure how much that will affect performance as we see it because I
> think the biggest performance factor is how we need to use the APIs
> given our task structure.  The public key handshake for initial
> connection may be faster.
> 
> I added the new code on a branch named update-wolfssh by copying in
> the source files as I did when creating the wolfssh and wolfssl
> components initially.  I'm running the new code on OVMS in my car and
> have given it basic testing by connecting with the ssh client and
> transferring files with scp.  I invite anyone else who is interested
> to test as well or to comment if there are any concerns about merging
> to the master branch.  There are some memory considerations.
> 
> I've added the complete wolfssl source tree even though we only use
> the wolfcrypt subset of wolfssl.  The update added a bunch of files
> and increased the required disk space from 18M to 43M.  Similarly,
> wolfssh added code for scp, sftp, ssh agent server code and also ssh
> clients that we are not using; that increased disk space from 2.0M to
> 2.6M.  I added our scp code before they implemented theirs and I have
> not examined their scp and sftp code to see if there would be any
> advantage in trying to adapt it to fit our non-blocking architecture.
> 
> I had to increase the size of the NetMan stack from 8K to 10K to avoid
> stack overflow.  With current master code the max used on my OVMS was
> 5616 whereas after the update it is 9700.
> 
> With the current master code, the amount of memory added by NetMan
> when an ssh connection was established was 2557 D/IRAM and 6108 SPIRAM
> for 8665 total.  With the update it was 1240 D/IRAM and 8768 SPIRAM
> for 10008 total.
> 
>                                                        -- Steve
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