"libnm-core/" is rather complicated. It provides a static library that
is linked into libnm.so and NetworkManager. It also contains public
headers (like "nm-setting.h") which are part of public libnm API.
Then we have helper libraries ("libnm-core/nm-libnm-core-*/") which
only rely on public API of libnm-core, but are themself static
libraries that can be used by anybody who uses libnm-core. And
"libnm-core/nm-libnm-core-intern" is used by libnm-core itself.
Move "libnm-core/" to "src/". But also split it in different
directories so that they have a clearer purpose.
The goal is to have a flat directory hierarchy. The "src/libnm-core*/"
directories correspond to the different modules (static libraries and set
of headers that we have). We have different kinds of such modules because
of how we combine various code together. The directory layout now reflects
this.
Add new configure option to set the path to "polkit-agent-helper-1".
The path cannot be obtained from pkg-config and `pkg-config
--variable=prefix polkit-agent-1` is not good enough.
On Fedora, the path is "/usr/lib/polkit-1/polkit-agent-helper-1".
On Debian Buster, the path is "/usr/lib/policykit-1/polkit-agent-helper-1"
On Debian Sid, the path is "/usr/libexec/polkit-agent-helper-1" (but
currently it is also symlinked from "/usr/lib/policykit-1/polkit-agent-helper-1".
(cherry picked from commit 801c41a11c)
Add new configure option to set the path to "polkit-agent-helper-1".
The path cannot be obtained from pkg-config and `pkg-config
--variable=prefix polkit-agent-1` is not good enough.
On Fedora, the path is "/usr/lib/polkit-1/polkit-agent-helper-1".
On Debian Buster, the path is "/usr/lib/policykit-1/polkit-agent-helper-1"
On Debian Sid, the path is "/usr/libexec/polkit-agent-helper-1" (but
currently it is also symlinked from "/usr/lib/policykit-1/polkit-agent-helper-1".
No big change, but eventually I' like to move all source
directories under src/. That must be done one after the other,
so the first step is to move libnm-core/ into src/. If libnm
gets loaded in between, that causes odd ordering.
"src/core" should not depend on "libnm" and vice versa, so this
should have little effect for now.
Our source tree also has certain consistency requirements. Since the
source is in git, this is a rather static check. However, we want to
ensure that future changes don't break it by adding a test.
Currently "src/" mostly contains the source code of the daemon.
I say mostly, because that is not true, there are also the device,
settings, wwan, ppp plugins, the initrd generator, the pppd and dhcp
helper, and probably more.
Also we have source code under libnm-core/, libnm/, clients/, and
shared/ directories. That is all confusing.
We should have one "src" directory, that contains subdirectories. Those
subdirectories should contain individual parts (libraries or
applications), that possibly have dependencies on other subdirectories.
There should be a flat hierarchy of directories under src/, which
contains individual modules.
As the name "src/" is already taken, that prevents any sensible
restructuring of the code.
As a first step, move "src/" to "src/core/". This gives space to
reorganize the code better by moving individual components into "src/".
For inspiration, look at systemd's "src/" directory.
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/743
Drop some "helper" variables that are only used once. These variables
spread out what is defined, and only make the meson file more complicated
to follow.
musl added support for reallocarray, but the function prototype is
declared in stdlib.h instead of malloc.h.
Update the check for reallocarray to check both in malloc.h and
stdlib.h.
https://man7.org/linux/man-pages/man3/reallocarray.3.html
We must set these compiler flags independent as to whether this
is a release build or a debug build.
In most cases, we don't differentiate between release and debug build
anyway. Granted, we have "-D more_asserts=100" and set "-O" CFLAGS,
but that is more granular and not a simple "buildtype".
In particular, these compiler flags apply to all kinds of builds.
This is important, because otherwise we get build failures, because
also in release build we want to build with `-Werror` and `-Wall`.
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/692
(cherry picked from commit c0c6470e4d)
We must set these compiler flags independent as to whether this
is a release build or a debug build.
In most cases, we don't differentiate between release and debug build
anyway. Granted, we have "-D more_asserts=100" and set "-O" CFLAGS,
but that is more granular and not a simple "buildtype".
In particular, these compiler flags apply to all kinds of builds.
This is important, because otherwise we get build failures, because
also in release build we want to build with `-Werror` and `-Wall`.
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/692
more_asserts are our NetworkManager specific assertions, and the only
point of having them at all (beside g_assert(), assert() and g_return*()),
is that these assertions are disabled by default in production.
meson always enabled them by default. That is definitely wrong.
autotools enables more_asserts by default if we build a devel version
from master. I think that is bad too, because (again) having these assertions
disabled by default is the only point of having them. Anyway, mimic
the behavior of autotools, to at least disable them in release builds.
jansson 2.7 was released October 2014. It's also in Ubuntu 16.06.
Other distros (like CentOS 7.5 and Debian Stretch/9) have both newer
versions.
Bump the requirement, simply because our CI does not use such old version
so it's not clear whether it works at all.
We anyway load libjansson with dlopen(), and already before it could
happen that libjansson is not available. In that case, we would not
crash, but simply proceed without json validation.
Since libnm-core no longer uses libjansson directly, but only via
"nm-glib-aux/nm-json.h", we can just always compile with that, and use
it at runtime. That means, libjansson is not a build dependency for
libnm anymore, so we don't need a compile time check.
Note that if you build without libjansson, then JANSSON_SONAME is
undefined, and loading it will still fail at runtime. So, even if
we now always build with all our code enabled, it only works if you
actually build with libjansson. Still, it's simpler to drop the
conditional build, as the only benefit is a (minimally) smaller
build.
The build for 0.46.0 probably isn't working anymore. Also, I'd like to
use dictionaries, which might not be available in such old meson
versions.
Anyway, it's not a problem. We in general aim to build on ancient
distros, like CentOS-7.5 and Ubuntu-16.04. But on those systems we
install meson using `pip3 install` anyway, where we get a recent meson
version.
Note that on Ubuntu 16.04, `pip3 install meson` would currently give us
meson 0.54.2. However, that meson requires a newer Python 3 version than
we have available. Hence, on Ubuntu 16.04 we actually want to install
`pip3 install meson==0.53.2`. See commit 5feba97cd1 ('gitlab-ci: use
old meson version on Ubuntu 16.04 to work with ninja-1.5.1').
We also still build on Fedora 28, which installs meson 0.47.2 from
packaging system. So, let's stick to 0.47.2 for now.
Install a NM-specific firewalld zone to be used for interfaces that
are used for connection sharing. The zone blocks all traffic to the
local machine except some protocols (DHCP, DNS and ICMP) and allows
all forwarded traffic.
Seen on Debian 9, clang-3.8 (1:3.8.1-24):
../libnm-core/nm-setting-bond.c:596:49: error: comparison of constant 32 with expression of type 'NMBondMode' is always true [-Werror,-Wtautological-constant-out-of-range-compare]
nm_assert (_NM_INT_NOT_NEGATIVE (mode) && mode < 32);
~~~~ ^ ~~
This warning is not useful. While it may be implementation defined how enum
values outside the defined ones are handled, we commonly rely on placing
special numeric values in enums (e.g. ((NMEnumType) -1)).
An enum is (with our compilers) just a glorified integer, and there is nothing
preventing it from being outside the enum values. The warning is not helpful
and outright wrong. Disable it.
See-also: https://bugs.llvm.org//show_bug.cgi?id=16154
Fixes: 957bb2e111 ('libnm: use binary search for _nm_setting_bond_option_supported() implementation')
The following used functions:
`compiler.has_link_argument`,
`link_whole arg in declare_dependency`,
`compiler.has_multi_link_argument`
are present only from meson 0.46.
After 1.22.0 is released, merge it back into master so that
1.22.0 is part of the history of master. That means,
$ git log --first-parent master
will also traverse 1.22.0 and 1.22-rc*.
Also bump the micro version to 1.23.1-dev to indicate that this is
after 1.22.0 is out.
See mesonbuild issue 5003.
Oddly, this isn't inside a method call, while we use ternaries
inside a method calls otherwise. Anyway, workaround this and
avoid the crash.
Fixes: c21c6bc0be ('build/meson: allow configuring default for main.auth-polkit setting')
(cherry picked from commit 0e3400bef7)
See mesonbuild issue 5003.
Oddly, this isn't inside a method call, while we use ternaries
inside a method calls otherwise. Anyway, workaround this and
avoid the crash.
Fixes: c21c6bc0be ('build/meson: allow configuring default for main.auth-polkit setting')
We always build PolicyKit support, because it merely depends on some
D-Bus calls. However, there are two things to configure:
- the default value for main.auth-polkit in NetworkManager.conf. This
is now called "-Dconfig_auth_polkit_default=$VAL".
- whether to install the policy file. This is called "-Dpolkit=$VAL".
These settings are mostly independent, so add "config_auth_polkit_default" to
make the default explicitly configurable.
(cherry picked from commit c21c6bc0be)
We always build PolicyKit support, because it merely depends on some
D-Bus calls. However, there are two things to configure:
- the default value for main.auth-polkit in NetworkManager.conf. This
is now called "-Dconfig_auth_polkit_default=$VAL".
- whether to install the policy file. This is called "-Dpolkit=$VAL".
These settings are mostly independent, so add "config_auth_polkit_default" to
make the default explicitly configurable.
- the variables in meson.build and in the meson-post-install.sh script
should have the same names.
- the positional command line arguments should be assigned to variables,
because the variable name acts like a documentation what the variable
means (contrary to the argument number).
- the boolean flags should not map to other special values, like
"enable_docs ? 'install_docs' : ''". The name "enable_docs" is
good already, it shall be either passed as 1 or 0 and use the name
consistently.
We don't need such data duplicated. The build setup should
have only one configuration_data() for patching such values.
Now we only have one global, immutable data_conf dictionary with
configuration values. Note that none of the users of data_conf uses all
entries, but as the entries are basically only dependent on the
meson/configure option and valid for the entire project, this simplifies
to handling.
Some variables belong to variables in their correspondent pkg-config
file.
These variables have been renamed to `dependency_variable` to
reflect the dependency and variables from pkg-config files they are
related to.
Some of these has also been fixed to use paths relative to
installation prefix.
Qt dependencies have been moved to the main build file where the
rest of dependencies are located. This makes it easier to find them.
The included directories has also reviewed and removed the
unnecessary ones.
The variable holding the compiler flags, `cflags`, has been renamed
to `c_flags` to be consistent with the rest of build files.
Different objects used in the `test-dispatcher-envp` target
have been grouped together.
The dependency over the `libnm` library has been removed as it is
unnecessary.
The `ifcfg-rh` meson build file installs a new post install script
to create the `network-config` directory.
This has been moved to the main post install file so it's easier to
find because all post install steps are together and it avoids and
extra post install script execution.
There are multiple conditional steps for building encryption
support. This is because the support varies from `gnutls` or `nss`.
This has been improved to reduce the number of used conditions.
The used meson modules, default directories and includes have been
moved to the start of the build file, just after project related
information, so they are available early.
Functions derived from generators as `configure_file`,
`custom_target` and `i18n.merge_file` can use placeholders like
`@BASENAME@` that removes the extension from the input filename
string.
The output string has been replaced by this placeholder that
allows in some cases the use of less variables.
After 1.20.0 is released, merge it back into master so that
1.20.0 is part of the history of master. That means,
$ git log --first-parent master
will also traverse 1.20.0 and 1.20-rc*.
Also bump the micro version to 1.21.1-dev to indicate that this is
after 1.20.0 is out.
The functionality of the ibft settings plugin is now handled by
nm-initrd-generator. There is no need for it anymore, drop it.
Note that ibft called iscsiadm, which requires CAP_SYS_ADMIN to work
([1]). We really want to drop this capability, so the current solution
of a settings plugin (as it is implemented) is wrong. The solution
instead is nm-initrd-generator.
Also, on Fedora the ibft was disabled and probably on most other
distributions as well. This was only used on RHEL.
[1] https://bugzilla.redhat.com/show_bug.cgi?id=1371201#c7
clang on CentOS 7.6 (3.4.2-9.el7) warns:
CC clients/tui/newt/clients_tui_newt_libnmt_newt_a-nmt-newt-button.o
In file included from ../clients/tui/newt/nmt-newt-button.c:26:
In file included from ../shared/nm-default.h:280:
../shared/nm-glib-aux/nm-macros-internal.h:1617:2: error: unknown warning group -Wstringop-truncation, ignored [-Werror,-Wunknown-pragmas]
NM_PRAGMA_WARNING_DISABLE ("-Wstringop-truncation");
^
../shared/nm-glib-aux/nm-macros-internal.h:419:9: note: expanded from macro NM_PRAGMA_WARNING_DISABLE
_Pragma(_NM_PRAGMA_WARNING_DO(warning))
^
<scratch space>:109:25: note: expanded from here
GCC diagnostic ignored "-Wstringop-truncation"
^
This warning totally defeats the purpose of why we use the pragma in the
first place.
After 1.18.0 is released, merge it back into master so that
1.18.0 is part of the history of master. That means,
$ git log --first-parent master
will also traverse 1.18.0 and 1.18-rc*.
Also bump the micro version to 1.19.1-dev to indicate that this is
after 1.18.0 is out.
Otherwise, the meson configure step fails with:
libnm/fake-typelib/meson.build:23:0: ERROR: The "dependencies" argument of gnome.compile_resources() can not
be used with the current version of glib-compile-resources due to
<https://bugzilla.gnome.org/show_bug.cgi?id=774368>
The fake-typelib is not really essential. Don't fix it, just print
a warning that we are unable to build it.
This removes libnm-glib, libnm-glib-vpn, and libnm-util for good.
The it has been replaced with libnm since NetworkManager 1.0, disabled
by default since 1.12 and no up-to-date distributions ship it for years
now.
Removing the libraries allows us to:
* Remove the horrible hacks that were in place to deal with accidental use
of both the new and old library in a single process.
* Relief the translators of maintenance burden of similar yet different
strings.
* Get rid of known bad code without chances of ever getting fixed
(libnm-glib/nm-object.c and libnm-glib/nm-object-cache.c)
* Generally lower the footprint of the releases and our workspace
If there are some really really legacy users; they can just build
libnm-glib and friends from the NetworkManager-1.16 distribution. The
D-Bus API is stable and old libnm-glib will keep working forever.
https://github.com/NetworkManager/NetworkManager/pull/308
This removes libnm-glib, libnm-glib-vpn, and libnm-util for good.
The it has been replaced with libnm since NetworkManager 1.0, disabled
by default since 1.12 and no up-to-date distributions ship it for years
now.
Removing the libraries allows us to:
* Remove the horrible hacks that were in place to deal with accidental use
of both the new and old library in a single process.
* Relief the translators of maintenance burden of similar yet different
strings.
* Get rid of known bad code without chances of ever getting fixed
(libnm-glib/nm-object.c and libnm-glib/nm-object-cache.c)
* Generally lower the footprint of the releases and our workspace
If there are some really really legacy users; they can just build
libnm-glib and friends from the NetworkManager-1.16 distribution. The
D-Bus API is stable and old libnm-glib will keep working forever.
https://github.com/NetworkManager/NetworkManager/pull/308
After 1.16.0 is released, merge it back into master so that
1.16.0 is part of the history of master. That means,
$ git log --first-parent master
will also traverse 1.16.0 and 1.16-rc*.
Also bump the micro version to 1.17.1-dev to indicate that this is
after 1.16.0 is out.
The defaults for test timeouts in meson is 30 seconds. That is not long
enough when running
$ NMTST_USE_VALGRIND=1 ninja -C build test
Note that meson supports --timeout-multiplier, and automatically
increases the timeout when running under valgrind. However, meson
does not understand that we are running tests under valgrind via
NMTST_USE_VALGRIND=1 environment variable.
Timeouts are really not expected to be reached and are a mean of last
resort. Hence, increasing the timeout to a large value is likely to
have no effect or to fix test failures where the timeout was too rigid.
It's unlikely that the test indeed hangs and the increase of timeout
causes a unnecessary increase of waittime before aborting.
It's not useful for us.
In file included from ../src/systemd/src/libsystemd/sd-event/sd-event.c:14:
../src/systemd/src/libsystemd/sd-event/event-source.h:195:36: error: field 'buffer' with variable sized type 'union inotify_event_buffer' not at the end of a struct or class is a GNU extension [-Werror,-Wgnu-variable-sized-type-not-at-end]
union inotify_event_buffer buffer;
^
Like we do with autotools, otherwise we get a warning:
[576/1030] Compiling C object src/25a6634@@NetworkManager@sta/nm-session-monitor.c.o.
../src/nm-session-monitor.c:31:5: warning: "SESSION_TRACKING_SYSTEMD" is not defined, evaluates to 0 [-Wundef]
#if SESSION_TRACKING_SYSTEMD && SESSION_TRACKING_ELOGIND
^~~~~~~~~~~~~~~~~~~~~~~~
The variable containing the list of compiler arguments to be checked
can be removed without any harm to readibility.
The variable has been removed by appending directly to the list of
common compiler arguments, those that are supported.
Although some paths related to DBus and PolicyKit are present in
their pkg-config files, those paths might not be writable for the
user. To solve this issue, some build options are present that can
be used to choose a different location.
However, usually these paths are relative to some other variables
such as `prefix`, `datadir`, etc. Using the `define_variable`
option the relative path can be change to point to a directory
under prefix.
These paths are now using relative paths based on the installation
`prefix` and their related options have been removed as they are
unnecessary now. Only `dbus_conf_dir` option has been left because
it must be modified depending on the distribution[0].
[0] contrib/fedora/rpm/NetworkManager.spec
meson is able to get variables defined in pkg-config files such as
directory paths. PolicyKit defines in its pkg-config file the path to
the directory where `policy` files are present.
This removes the `polkit_dir` option to ease the move to start using
those variables. The `polkit` variable has also been converted to
boolean.
Fedora spec script has also been updated accordingly.
We need to copy all introspection files to the same directory when
building the documentation.
Note that we only require Meson 0.44, but for the documentation at
least 0.46 is needed because of a new functionality of
gnome.gdbus_codegen(). In this way we can still build on Travis CI
(without documentation).
Adapt the meson post-installation script to handle the $DESTDIR
variable supplied by user to specify the installation target
directory. While at it, convert the script to shell because it seems
simpler to me.
After 1.14.0 is released, merge it back into master so that
1.14.0 is part of the history of master. That means,
$ git log --first-parent master
will also traverse 1.14.0 and 1.14-rc*.
Also bump the micro version to 1.15.1-dev to indicate that this is
after 1.14.0 is out.
Some path variable like $(bindir), $(datadir), etc. are special for
autotools and must be handled separately through config-extra.h.
But dhcp path variables are just normal variables defined through
the configure script and should go into config.h.
(cherry picked from commit 087c367d62)
dhcpcd version 6, the first supporting IPv6, was released more than 5
years ago. Remove all checks on version number and IPv6 support.
(cherry picked from commit e0c49d7341)
Handle the iptables, dnsmasq and dnssec-trigger paths in the same way
through common code.
The path set by user must be accepted as is, even if does not exist,
because this is a requirement for cross-compilation. When user does
not specify a path, search a predefined set of paths and fall back to
an hardcoded one.
(cherry picked from commit 220dea0948)
Some path variable like $(bindir), $(datadir), etc. are special for
autotools and must be handled separately through config-extra.h.
But dhcp path variables are just normal variables defined through
the configure script and should go into config.h.
Handle the iptables, dnsmasq and dnssec-trigger paths in the same way
through common code.
The path set by user must be accepted as is, even if does not exist,
because this is a requirement for cross-compilation. When user does
not specify a path, search a predefined set of paths and fall back to
an hardcoded one.
If the library is available, let's at least compile both
crypto backends.
That is helpful when developing on crypto backends, so that
one does not have to configure the build twice.
With autotools, the build is only run during `make check`.
Not for meson, but that is generally the case with our meson
setup, that it also builds tests during the regular build step.
suspend-resume must be selectable, out of for possible options.
We can do auto-detection based on present libraries, but it
shall be selectable. Like it is with autotools.
- always define the SESSION_TRACKING_* defines to replace
"#ifdef" with "#if".
- drop defining the consolekit database path CKDB_PATH in
config.h. The path was not customizable via configure/meson.
- fix meson build to enable consolekit support for session tracking
without also enabling logind/elogind session tracking.
logind/elogind is mutually exclusive, but consolekit session tracking
goes together just fine.
1) the command line gets shorter. I frequently run `make V=1` to see
the command line arguments for the compiler, and there is a lot
of noise.
2) define each of these variables at one place. This makes it easy
to verify that for all compilation units, a particular
define has the same value. Previously that was not obvious or
even not the case (see commit e5d1a71396
and commit d63cf1ef2f).
The point is to avoid redundancy.
3) not all compilation units need all defines. In fact, most modules
would only need a few of these defines. We aimed to pass the necessary
minium of defines to each compilation unit, but that was non-obvious
to get right and often we set a define that wasn't used. See for example
"src_settings_plugins_ibft_cppflags" which needlessly had "-DSYSCONFDIR".
This question is now entirely avoided by just defining all variables in
a header. We don't care to find the minimum, because every component
gets anyway all defines from the header.
4) this also avoids the situation, where a module that previously did
not use a particular define gets modified to require it. Previously,
that would have required to identify the missing define, and add
it to the CFLAGS of the complation unit. Since every compilation
now includes "config-extra.h", all defines are available everywhere.
5) the fact that each define is now available in all compilation units
could be perceived as a downside. But it isn't, because these defines
should have a unique name and one specific value. Defining the same
name with different values, or refer to the same value by different
names is a bug, not a desirable feature. Since these defines should
be unique accross the entire tree, there is no problem in providing
them to every compilation unit.
6) the reason why we generate "config-extra.h" this way, instead of using
AC_DEFINE() in configure.ac, is due to the particular handling of
autoconf for directory variables. See [1].
With meson, it would be trivial to put them into "config.h.meson".
While that is not easy with autoconf, the "config-extra.h" workaround
seems still preferable to me.
[1] https://www.gnu.org/software/autoconf/manual/autoconf-2.63/html_node/Installation-Directory-Variables.html
After 1.12.0 is released, merge it back into master so that
1.12.0 is part of the history of master. That means,
$ git log --first-parent master
will also traverse 1.12.0 and 1.12-rc*.
Also bump the micro version to 1.13.1-dev to indicate that this is
after 1.12.0 is out.
This makes package updates more robust, avoiding in-place replaces of
the plugins.
Previously, if an upgrade transaction was terminated, NetworkManager
library could end up being of a different version than the plugins.
If the user was unfortunate enough to connect using a connection that
required a plugin (say, Wi-Fi), he would be left without a network
connection making it somewhat inconvenient to recover from the botched
upgrade.
This makes the whole situation a little bit less sad.
The VPN plugins are kept where they always have been -- the path is not
qualified with a version number.
With autotools, we use libtool so that the right libraries are
automatically found. Still, we won't find the right GI typelib.
Add a mechanism so that when make/meson invokes the run-nm-test.sh
runner, it passes the build-root directory.
Also, try to autodetect when invoked manually.
This makes package updates more robust, avoiding in-place replaces of
the plugins.
Previously, if an upgrade transaction was terminated, NetworkManager
library could end up being of a different version than the plugins.
If the user was unfortunate enough to connect using a connection that
required a plugin (say, Wi-Fi), he would be left without a network
connection making it somewhat inconvenient to recover from the botched
upgrade.
This makes the whole situation a little bit less sad.
Supporting PolicyKit required no additional library, just extra code
to handle the D-Bus calls. For that, there was a compile time option
to even stip out that code. Note, that you could (and still can)
configure the system not to use policy-kit. The point was to reduce
the binary size in case you don't need it.
Remove this. I guess, we we aim for such aggressive optimization of
the binary size, we should instead make all device types disablable
at configuration time. We don't do that either and other low hanging
fruits, because it's better to always enable features, unless they
require external dependencies.
Also, the next commit will make more use of NMAuthManager. So, having
it disabled at compile time, makes even less sense.
From libnl3, we only used the helper function to parse/generate netlink
messages and the socket functions to send/receive messages. We don't
need an external dependency to do that, it is simple enough.
Drop the libnl3 dependency, and replace all missing code by directly
copying it from libnl3 sources. At this point, I mostly tried to
import the required bits to make it working with few modifications.
Note that this increases the binary size of NetworkManager by 4736 bytes
for contrib/rpm build on x86_64. In the future, we can simplify the code
further.
A few modifications from libnl3 are:
- netlink errors NLE_* are now in the domain or regular errno.
The distinction of having to bother with two kinds of error
number domains was annoying.
- parts of the callback handling is copied partially and unused parts
are dropped. Especially, the verbose/debug handlers are not used.
In following commits, the callback handling will be significantly
simplified.
- the complex handling of seleting ports was simplified. We now always
let kernel choose the right port automatically.
