oFono: Plugin Has the Incorrect Conditional for Evaluating When a Context Was Successfully Added

Team Connection Manager and Ofono:

At the appropriate moment in the oFono plugin lifecycle, it gets and evaluates contexts from a given Cellular modem. Depending on the HNI/MCC+MNC and the network operator, there may be one or more such contexts, each with a different type.

Within ‘cm_get_contexts_reply', each received context is iterated on, evaluating each for the type ‘internet' by calling ‘add_cm_context'. If the context is not of type ‘internet’, ‘cm_get_contexts_reply' should continue to iterate until all contexts are exhausted or a matching context is found.

The return semantics of ‘add_cm_context’ are ‘-EINVAL' if a context *not* of the type ‘internet' is evaluated; otherwise zero ('0') if a context of type ‘internet' was found.

However, the current conditional logic of ‘cm_get_contexts_reply' is:

    while (dbus_message_iter_get_arg_type(&dict) == DBUS_TYPE_STRUCT) {
        const char *context_path;

        dbus_message_iter_recurse(&dict, &entry);
        dbus_message_iter_get_basic(&entry, &context_path);

        dbus_message_iter_next(&entry);
        dbus_message_iter_recurse(&entry, &value);

        if (add_cm_context(modem, context_path, &value))
            break;

        dbus_message_iter_next(&dict);
    }

So, assuming a set of contexts from, for example Verizon, such as '[ { vzwims, ims }, { vzwinternet, internet }, { vzwapp, wap } ]', then the above logic will encounter '{ vzwims, ims }', evaluate that it is not of type ‘internet', return ‘-EINVAL' from ‘add_cm_context', that will satisfy the conditional and trigger the ‘break' from the ‘while' loop and context iteration will terminate. This then misses the second '{ vzwinternet, internet }' context that was sought and the Cellular interface will never come up on connman.

See https://github.com/Nuovations/connman/issues/133.

Patch forthcoming which amounts to:

        if (add_cm_context(modem, context_path, &value) == 0)
            break;

Best,

Grant

-- 
Principal
Nuovations

[email protected]
https://www.nuovations.com/