We've been working on MMS support for Ubuntu Touch recently and have run
into a couple of stumbling blocks, so I have a few questions about the
current MMS logic in oFono ( we're still 1.12 based ), and in particular
the provisioning/management of gprs-contexts.
As part of this work, we're planning to switch from using the builtin
gprs 'provision' plugin, to the new android-provision/apndb plugin (
originally written by Simon Busch ) which uses the file apns-conf.xml
instead of mbpi's serviceproviders.xml.
There are a couple of issues we ran into...
1. How to represent APNs that support multiple usages types?
The "type" attribute in apns-conf.xml is a list vs. the single type
defined by a gprs_context.
The android-apndb plugin uses TYPE_INTERNET for APNs which support
multiple types. In order to properly support MMS, the core code needed
to be modified to allow the MMS properties to be additionally be set on
a TYPE_INTERNET context. Thus if an APN supports both Internet and MMS,
our DownloadManager can grab the additional MMS properties from the
context and handle MMS traffic.
Now perhaps I missed something and there is a way to represent a
combined usage APN ( maybe using TYPE_ANY? ), but I couldn't see how to
accomplish without changes to the core gprs code.
2. No way to disable core ofono TYPE_MMS network config.
The core gprs_context code has special logic for TYPE_MMS contexts which
configures the HTTP proxy using networking ioctl requests. We have an
external download manager that handles the actual download of content
from the message center. As it has logic to handle HTTP proxies
already, if we use TYPE_MMS, we'd need a way to disable ofono's builtin
logic.
Would it make sense to add a command-line option to control this behavior?
3. No way to associate additional APN properties with a gprs_context.
apns-conf.xml has many additional APN attributes which don't map
directly to gprs_context properties ( eg. authtype, mvno_type, ... ).
"types" is especially important, as without it, we can't tell exactly
which services are supported by the APN ( as the plugin sets the type to
TYPE_INTERNET ).
So, here's a summary of the changes I made ( again with MMS support as
one of the main goals ). Also note, this is WIP, and if there other
approaches I should consider, I'd appreciate some feedback.
My latest code containing these changes can be found in the following
github branch.
https://github.com/tonyespy/ofono/tree/mms-new
Note, if it'd be more helpful, I can email the patches directly to the
list with a "RFC" in the subject line, however I think there's little
chance that they'd be taken "as is".
1. Modified the core gprs code to allow MMS proxy and message center
properties to be set on OFONO_GPRS_CONTEXT_TYPE_INTERNET contexts.
2. Modified the android_apndb plugin such that it always creates
TYPE_INTERNET contexts ( even for standalone MMS APNs, as this allows us
to bypass the previously mentioned HTTP proxy logic ).
3. Modified the core gprs_context code to allow a new property called
'ExtraData' to be set during provisioning. This property is a DBus
dictionary type ( ie. like 'Setttings' ), and is used by provisioning to
convey any attributes in apn-confs.xml which don't map directly to ofono
gprs_contexts. The current impl doesn't support writes to ExtraData
from DBus yet. We may add support to allow a "preferred" attribute (
ie. usabe by our Cellular Settings UI ).
If there's a way to accomplish any of these changes via plugins alone, I
would've gone that route... Also, if I've missed any other hooks that
might help us accomplish these changes, I'm welcome to suggestions.
Regards,
/tony
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