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Thomas Haller d8a31794c8 connectivity: rework async connectivity check requests
An asynchronous request should either be cancellable or not keep
the target object alive. Preferably both.

Otherwise, it is impossible to do a controlled shutdown when terminating
NetworkManager. Currently, when NetworkManager is about to terminate,
it just quits the mainloop and essentially leaks everything. That is a
bug. If we ever want to fix that, every asynchronous request must be
cancellable in a controlled way (or it must not prevent objects from
getting disposed, where disposing the object automatically cancels the
callback).

Rework the asynchronous request for connectivity check to

- return a handle that can be used to cancel the operation.
  Cancelling is optional. The caller may choose to ignore the handle
  because the asynchronous operation does not keep the target object
  alive. That means, it is still possible to shutdown, by everybody
  giving up their reference to the target object. In which case the
  callback will be invoked during dispose() of the target object.

- also, the callback will always be invoked exactly once, and never
  synchronously from within the asynchronous start call. But during
  cancel(), the callback is invoked synchronously from within cancel().
  Note that it's only allowed to cancel an action at most once, and
  never after the callback is invoked (also not from within the callback
  itself).

- also, NMConnectivity already supports a fake handler, in case
  connectivity check is disabled via configuration. Hence, reuse
  the same code paths also when compiling without --enable-concheck.
  That means, instead of having #if WITH_CONCHECK at various callers,
  move them into NMConnectivity. The downside is, that if you build
  without concheck, there is a small overhead compared to before. The
  upside is, we reuse the same code paths when compiling with or without
  concheck.

- also, the patch synchronizes the connecitivty states. For example,
  previously `nmcli networking connectivity check` would schedule
  requests in parallel, and return the accumulated result of the individual
  requests.
  However, the global connectivity state of the manager might have have
  been the same as the answer to the explicit connecitivity check,
  because while the answer for the manual check is waiting for all
  pending checks to complete, the global connectivity state could
  already change. That is just wrong. There are not multiple global
  connectivity states at the same time, there is just one. A manual
  connectivity check should have the meaning of ensure that the global
  state is up to date, but it still should return the global
  connectivity state -- not the answers for several connectivity checks
  issued in parallel.
  This is related to commit b799de281b
  (libnm: update property in the manager after connectivity check),
  which tries to address a similar problem client side.
  Similarly, each device has a connectivity state. While there might
  be several connectivity checks per device pending, whenever a check
  completes, it can update the per-device state (and return that device
  state as result), but the immediate answer of the individual check
  might not matter. This is especially the case, when a later request
  returns earlier and obsoletes all earlier requests. In that case,
  earlier requests return with the result of the currend devices
  connectivity state.

This patch cleans up the internal API and gives a better defined behavior
to the user (thus, the simple API which simplifies implementation for the
caller). However, the implementation of getting this API right and properly
handle cancel and destruction of the target object is more complicated and
complex. But this but is not just for the sake of a nicer API. This fixes
actual issues explained above.

Also, get rid of GAsyncResult to track information about the pending request.
Instead, allocate our own handle structure, which ends up to be nicer
because it's strongly typed and has exactly the properties that are
useful to track the request. Also, it gets rid of the awkward
_finish() API by passing the relevant arguments to the callback
directly.
2018-04-10 15:11:23 +02:00
clients Add calls to g_simple_async_result_set_check_cancellable 2018-03-08 14:52:45 +01:00
contrib contrib/nm-live-vm: remove nm-live-vm scripts 2018-03-27 11:13:41 +02:00
data systemd: make enablement of n-m-wait-online.service follow n-m.service 2018-03-14 10:24:45 +01:00
dispatcher all: replace non-leading tabs with spaces 2018-02-07 13:32:04 +01:00
docs docs: fix VPN chapter ID 2018-03-16 12:56:22 -05:00
examples libnm: rework checkpoint API 2018-04-04 14:02:13 +02:00
introspection checkpoint: allow resetting the rollback timeout via D-Bus 2018-04-04 14:02:13 +02:00
libnm libnm: rework checkpoint API 2018-04-04 14:02:13 +02:00
libnm-core docs: fix typo in nm-settings-ifcfg-rh:dhcp-client-id doc 2018-04-06 18:53:49 +02:00
libnm-glib libnm-glib: do not use deprecated Gtk-Doc Type: and Virtual: tags 2018-03-26 12:46:22 +02:00
libnm-util libnm-util: Fix a minor type problem with GValue 2018-02-08 17:47:53 +01:00
m4 m4: parametrize flags variable 2018-02-16 16:06:59 +01:00
man man: update NetworkManager.conf man page to account for stub-resolv.conf (#68) 2018-02-18 14:22:24 +01:00
po po: update Czech translation 2018-03-30 22:01:50 +02:00
shared shared/tests: add nmtst_assert_nonnull() macro 2018-04-09 20:16:30 +02:00
src connectivity: rework async connectivity check requests 2018-04-10 15:11:23 +02:00
tools tools/run-nm-test.sh: add -d option to set NMTST_DEBUG=d 2018-04-09 20:16:30 +02:00
vapi meson: Use string variables extensively 2018-01-10 12:22:55 +01:00
.dir-locals.el misc: add toplevel .dir-locals file that tells Emacs to show trailing whitespace 2013-03-08 15:15:28 +01:00
.gitignore gitignore: ignore *.pyc files 2018-04-04 14:57:07 +02:00
.travis.yml travis: install meson 0.44.1 for travis' meson build 2018-03-05 17:47:21 +01:00
AUTHORS misc: update maintainers and authors 2016-04-21 13:39:03 -05:00
autogen.sh build: fix gtk-doc/introspection handling for build 2016-11-28 12:43:51 +01:00
ChangeLog Changelog: remove and replace the changelog by a stub 2017-02-14 17:39:46 +01:00
config.h.meson systemd: merge branch systemd into master 2018-04-04 17:47:22 +02:00
configure.ac systemd: merge branch systemd into master 2018-04-04 17:47:22 +02:00
CONTRIBUTING Make licensing of contributions more explicit 2017-07-25 07:16:35 +02:00
COPYING docs: create new master NM documentation module 2011-02-16 16:24:16 -06:00
linker-script-binary.ver iface-helper/build: add linker version script 2016-10-13 21:33:33 +02:00
linker-script-devices.ver devices/build: use one linker-script-devices.ver for all device plugins 2016-10-13 21:36:06 +02:00
linker-script-settings.ver settings/build: add linker version script for settings plugins 2016-10-13 21:33:33 +02:00
MAINTAINERS misc: update maintainers and authors 2016-04-21 13:39:03 -05:00
Makefile.am checkpoint: embed CList in NMCheckpoint instance 2018-04-04 14:02:13 +02:00
Makefile.examples examples: add python utils for examples 2018-04-04 14:02:13 +02:00
Makefile.glib build: include "config.h" in nm*enum-types.c sources 2015-10-05 15:01:38 +02:00
Makefile.vapigen build: fix make always re-making vapigen target 2016-10-21 18:46:03 +02:00
meson.build systemd: merge branch systemd into master 2018-04-04 17:47:22 +02:00
meson_options.txt build: Rename settings-docs.c file 2018-01-12 09:39:06 +01:00
meson_post_install.py build: add initial support for meson build system 2017-12-13 15:48:50 +01:00
NetworkManager.pc.in build: update NetworkManager.pc 2013-01-29 16:17:30 -05:00
NEWS dhcp: dhclient: set type 0 for printable client IDs 2018-03-15 17:25:27 +01:00
README trivial: typo fixes 2010-09-25 00:34:10 -05:00
TODO all: drop trailing spaces 2018-02-07 13:32:04 +01:00
valgrind.suppressions valgrind: update glib2 suppression for Fedora 27 2017-11-15 17:05:01 +01:00
zanata.xml po: add Zanata configuration 2016-04-05 14:35:53 +02:00

******************
2008-12-11: NetworkManager core daemon has moved to git.freedesktop.org!

git clone git://git.freedesktop.org/git/NetworkManager/NetworkManager.git
******************


Networking that Just Works
--------------------------

NetworkManager attempts to keep an active network connection available at all
times.  The point of NetworkManager is to make networking configuration and
setup as painless and automatic as possible.  NetworkManager is intended to
replace default route, replace other routes, set IP addresses, and in general
configure networking as NM sees fit (with the possibility of manual override as
necessary).  In effect, the goal of NetworkManager is to make networking Just
Work with a minimum of user hassle, but still allow customization and a high
level of manual network control.  If you have special needs, we'd like to hear
about them, but understand that NetworkManager is not intended for every
use-case.

NetworkManager will attempt to keep every network device in the system up and
active, as long as the device is available for use (has a cable plugged in,
the killswitch isn't turned on, etc).  Network connections can be set to
'autoconnect', meaning that NetworkManager will make that connection active
whenever it and the hardware is available.

"Settings services" store lists of user- or administrator-defined "connections",
which contain all the settings and parameters required to connect to a specific
network.  NetworkManager will _never_ activate a connection that is not in this
list, or that the user has not directed NetworkManager to connect to.


How it works:

The NetworkManager daemon runs as a privileged service (since it must access
and control hardware), but provides a D-Bus interface on the system bus to
allow for fine-grained control of networking.  NetworkManager does not store
connections or settings, it is only the mechanism by which those connections
are selected and activated.

To store pre-defined network connections, two separate services, the "system
settings service" and the "user settings service" store connection information
and provide these to NetworkManager, also via D-Bus.  Each settings service
can determine how and where it persistently stores the connection information;
for example, the GNOME applet stores its configuration in GConf, and the system
settings service stores it's config in distro-specific formats, or in a distro-
agnostic format, depending on user/administrator preference.

A variety of other system services are used by NetworkManager to provide
network functionality: wpa_supplicant for wireless connections and 802.1x
wired connections, pppd for PPP and mobile broadband connections, DHCP clients
for dynamic IP addressing, dnsmasq for proxy nameserver and DHCP server
functionality for internet connection sharing, and avahi-autoipd for IPv4
link-local addresses.  Most communication with these daemons occurs, again,
via D-Bus.


Why doesn't my network Just Work?

Driver problems are the #1 cause of why NetworkManager sometimes fails to
connect to wireless networks.  Often, the driver simply doesn't behave in a
consistent manner, or is just plain buggy.  NetworkManager supports _only_
those drivers that are shipped with the upstream Linux kernel, because only
those drivers can be easily fixed and debugged.  ndiswrapper, vendor binary
drivers, or other out-of-tree drivers may or may not work well with
NetworkManager, precisely because they have not been vetted and improved by the
open-source community, and because problems in these drivers usually cannot
be fixed.

Sometimes, command-line tools like 'iwconfig' will work, but NetworkManager will
fail.  This is again often due to buggy drivers, because these drivers simply
aren't expecting the dynamic requests that NetworkManager and wpa_supplicant
make.  Driver bugs should be filed in the bug tracker of the distribution being
run, since often distributions customize their kernel and drivers.

Sometimes, it really is NetworkManager's fault.  If you think that's the case,
please file a bug at http://bugzilla.gnome.org and choose the NetworkManager
component.  Attaching the output of /var/log/messages or /var/log/daemon.log
(wherever your distribution directs syslog's 'daemon' facility output) is often
very helpful, and (if you can get) a working wpa_supplicant config file helps
enormously.