This repo provides factory diagnostic infrastructure for embedded systems.

Theory of operation:

    The factory server has two ethernet interfaces, one that goes to the world
    (via the factory) and one that goes DUTs via a switch. 

    DUTs attach to the DUT subnet via pionic test controller or USB ethernet
    switch.

    The DUT boots normal production code, allowing testing of DUTs even if
    secure boot is enabled.

    At some point early in the boot, the normal production code executes the
    'startdiag.sh'. The script tries to detect if it is in the factory, either
    by listening for an ethernet "beacon" or by performing a specific HTTP
    fetch.

    If the script decides that DUT really is in the factory, it downloads a
    tarball from the factory server via https. The factory server SSL key is
    known to the startdiag.sh script in advance, if the key is invalid then
    diagnostics will not proceed. This prevents exploitation of this mechanism
    in the field. (Security of the factory SSL key is of utmost importance.)

    Otherwise the files in the tarball are extracted and the DUT invokes the
    dodiag.sh script contained therein. dodiag.sh can do whatever it wishes to
    test the system, but typically it passes control to a dodiag executable which in
    turn executes various tests that were included in the downloaded tarball.

    The server maintains a DHCP server which assigns static IPs to pre-defined
    MAC address of pionic controller or USB ethernet dongle. The last octet of
    the IP address is the test station ID.

    It's important to note that the DUT tests itself, the external systems only
    supply support for the test code running on the DUT.

    The server provides access to a CGI that is invoked by the DUT during
    testing to manipulate test status and output data. The server also provides
    a set of CGIs that can be invoed by factory personnel to look at diagnostic
    results and configure the server.
    
    The server runs a DHCP server on the DUT interface which assigned static
    IPs to the pre-defined MAC address of pionic controller or USB ethernet
    dongle.  The last octet of the IP address is the test station ID.

    The server acts as a NAT router to allow DUTs (and pionic controllers) to
    access the internet for name resolution, NTP, etc.


The 'server' directory contains everything necessary to configure the factory server. See the README in that directory.

The 'client' directory contains example code that runs on DUT and interacts
with server and CGIs.

    startdiag.sh - this is code that is shipped with the production code and tries to detect factory environment during startup.

    dodiag,sh - this goes in the diagnostic tarball, it is started by startdiag.sh after the tarball is downloaded. It prepares the DUT to perform diagnostics.

    dodiag - this also goes in the diagnostics tarball, it invokes the various tests and interacts with the factory server.