panic on GRASP message with empty option

[mcr]

via Brian E Carpenter

One more panic:
thread 'tokio-runtime-worker' panicked at 'index out of bounds: the len is 0 but the index is 0', src/grasp.rs:161:11

That's on this statement:

match ctarray[0] {
    CborType::Integer(O_IPV6_LOCATOR) => grasp_parse_ipv6_locator(ctarray),
    CborType::Integer(O_IPV4_LOCATOR) => grasp_parse_ipv4_locator(ctarray),
    CborType::Integer(O_FQDN_LOCATOR) => grasp_parse_fqdn_locator(ctarray),
    CborType::Integer(O_URI_LOCATOR)  => grasp_parse_uri_locator(ctarray),
    _ => return Err(ConnectError::MisformedGraspObjective)
}

It looks as if your code received a GRASP message including an empty option where a locator option was expected. That is legal, for the case where the flood sender doesn't desire to provide a locator:

   message /= flood-message
   flood-message = [M_FLOOD, session-id, initiator, ttl,
                   +[objective, (locator-option / [])]]

For the ACP or BRSKI objectives, you would never send an empty option, but at least one of my demo apps does flood an objective without a locator.

I see that my code for incoming floods has an explicit test for this case..