Aleksander Morgado
f31f42dda1
When IPv6 is requested during a connection attempt, two things may happen: either the modem itself runs SLAAC, or otherwise the host is the one that should run SLAAC. Until now we have assumed that the first IP configuration query that is run upon finishing a connection attempt always gives us a "final result", so if the modem did run SLAAC by itself, we would have expected to see a global IPv6 reported in that first query. And if there was no global IPv6 reported, then we would have assumed that the host was the one tasked with running SLAAC. There is a third option that we now consider, which is the case where the first IP configuration query does not report a global IPv6, but the modem is really running SLAAC, and the global IPv6 address will be reported via a IP configuration indication as soon as SLAAC finishes. This third option cannot be assumed by default, because it introduces the possibility of MM waiting for the indication with the SLAAC results and that indication never arriving in the 10s timeout used as default. If a modem is supposed to use this third option, the feature must be explicitly flagged by the modem plugin.
ModemManager
ModemManager provides a unified high level API for communicating with mobile broadband modems, regardless of the protocol used to communicate with the actual device (Generic AT, vendor-specific AT, QCDM, QMI, MBIM...).
Using
ModemManager is a system daemon and is not meant to be used directly from the command line. However, since it provides a DBus API, it is possible to use 'dbus-send' commands or the new 'mmcli' command line interface to control it from the terminal. The devices are queried from udev and automatically updated based on hardware events, although a manual re-scan can also be requested to look for RS232 modems.
Implementation
ModemManager is a DBus system bus activated service (meaning it's started automatically when a request arrives). It is written in C, using glib and gio. Several GInterfaces specify different features that the modems support, including the generic MMIfaceModem3gpp and MMIfaceModemCdma which provide basic operations for 3GPP (GSM, UMTS, LTE) or CDMA (CDMA1x, EV-DO) modems. If a given feature is not available in the modem, the specific interface will not be exported in DBus.
Plugins
Plugins are loaded on startup, and must implement the MMPlugin interface. It consists of a couple of methods which tell the daemon whether the plugin supports a port and to create custom MMBroadbandModem implementations. It most likely makes sense to derive custom modem implementations from one of the generic classes and just add (or override) operations which are not standard. There are multiple fully working plugins in the plugins/ directory that can be used as an example for writing new plugins. Writing new plugins is highly encouraged! The plugin API is open for changes, so if you're writing a plugin and need to add or change some public method, feel free to suggest it!
License
The ModemManager and mmcli binaries are both GPLv2+. The libmm-glib library is LGPLv2+.
Code of Conduct
Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms, which you can find in the following link: https://www.freedesktop.org/wiki/CodeOfConduct
CoC issues may be raised to the project maintainers at the following address: modemmanager-devel-owner@lists.freedesktop.org