Async API review by d12fk · Pull Request #1 · d12fk/dbus-asio

d12fk · 2022-04-14T12:31:48Z

This PR is for reviewing the changes, and also to get notified when new stuff is force pushed.

Signed-off-by: Heiko Hund <heiko@openvpn.net>

* remove quotes from name (not needed) * while at it rephrase * remove empty Requires Signed-off-by: Heiko Hund <heiko@openvpn.net>

d12fk · 2022-04-15T00:58:10Z

src/dbus_names.h

        enum Type {
            BusName, UniqueName, WellKnownName, ErrorName,
            InterfaceName, NamespaceName, MemberName };
-        static constexpr std::array<const char*, 7> nameStr = {


@mikecrowe this symbol was missing according to clang, has this to do with -fvisibility as well? If so what's happening?
Moving the symbol to the .cpp made it link again

This might be similar to 7ca1104.

I must admit that I'm not at all expert with -fvisibility, especially with C++, and the need to use -fuse-ld=gold in ff563e1 doesn't inspire confidence that all is well. Does the problem go away if you revert ff563e1?

Reverting didn't help: https://github.com/d12fk/dbus-asio/runs/6042722273
I have no idea what clang doesn't like here.

This works with -std=c++17, so I guess there's an issue with std::array that's resolved in later a std. For now I would like to keep it to -std=c++1y, as RHEL7 is that far back and supported for another year.

RHEL7 is that far back and supported for another year.

RHEL7 is supported until end of June 2024, so two more years. It by default ships with GCC 4.8.5 (IIRC), which only supports -std=c++1y (which is most of, but not all, C++14 features). That said, the devtoolset-10 software library is available, which gives GCC-10.3, with should support -std=c++17. OpenVPN 3 Linux is already being built with this compiler for the official releases.

This set of types makes it possible to validate strings according to the requirements for certain "names" as specified in the DBus spec. The sections "Valid Names", "Valid Object Paths" and "Match Rules" in the spec define the rules for validaton. The types are: * UniqueName - a unique connection name * WellKnownName - a unique name alias, aka well-known bus name * BusName - either one of the previous two, a "bus address" * ObjectPath - a object path as used in the message header * InterfaceName - a interface name as used in the message header * MemberName - a member name as used in the message header * ErrorName - a error name as used in the message header * NamespaceName - a special kind of bus name used in match rules The types are opaque, since they take a C or std:: string and have an operator std::string(). Signed-off-by: Heiko Hund <heiko@openvpn.net>

Change the way MatchRules are constructed. Instead of taking a string and then parsing it, take the match keys in a structured way, validate them and generate a match rule string from them. Added support for missing match rules keys, except "eavesdrop", since that one is deprecated in favor of the "BecomeMonitor" method. Signed-off-by: Heiko Hund <heiko@openvpn.net>

Let the user decide which version of ASIO to build against. Users of dbus-asio need to link against the same version of asio, so this adds some flexibility if they can't or don't want to switch to boost. Signed-off-by: Heiko Hund <heiko@openvpn.net>

This error abstraction is able to hold either a error_code as used by asio, or a DBus::Message::Error as received from dbus. Signed-off-by: Heiko Hund <heiko@openvpn.net>

Also added some spacing after 8 bytes to make things look prettier. Output looks like this now (hex shortened): 6c ... 00 02 ... 00 06 ... 00 | l....... ........ ..s..... 6f ... 65 64 ... 2e 44 ... 00 | org.free desktop. DBus.... 01 ... 00 2f ... 65 65 ... 70 | ..o..... /org/fre edesktop 2f ... 00 02 ... 00 6f ... 65 | /DBus... ..s..... org.free 64 ... 2e 44 ... 00 03 ... 00 | desktop. DBus.... ..s..... 52 ... 4e 61 ... 00 08 ... 00 | RequestN ame..... ..g..su. 0a ... 74 2e ... 00 00 ... | ....test .steev.. .... So, you can tell pretty good what's going on in the message blob without dissecting the bits carefully. Signed-off-by: Heiko Hund <heiko@openvpn.net>

The previous approach using boost::any as the generic DBus type had the downside that any data(type) could be fed into it, no matter if DBus actually supports the datatype. Instead, there's now a DBus::Type::Any which behaves more like a std::variant with some DBus specific extras. It serves as the container for the others inheriting from DBus::Type and as a generic type the DBus container types can store. This type system is more type safe than before, so there's no need to compare types by their serialized string form, as each can be cast back to the native C++ type. The Signature type now validates the signature string passed to it. So, it is no longer possible to use DictEntry's outside of an Array, like the standard mandates. The ObjectPath type makes use of the DBus::ObjectPath "name" and the validation done therein. The Array type checks the all Array::add()ed elements have the correct signature and/or type. Made the DBus::Type::toString() output a bit more compact and reflect the container types a bit better by using [], {} and () in the right places. Signed-off-by: Heiko Hund <heiko@openvpn.net>

DBus has support for passing file descriptors between processes via the Unix sockets. This adds the respective type and prepares buffer and streams to handle such FDs when sending and receiving messages. Signed-off-by: Heiko Hund <heiko@openvpn.net>

Most of things are now done in the the base type DBus::Message (was: DBus::Message::Base). As a consequence the types representing the four DBus messages hardly have any code left and their implementation was moved in with the rest of the message handling code. The DBus::Message::Header now makes use of the DBus type system and has support for all header fields. It also got a toString() for logging. Same goes for the body, a.k.a parameters, which can now be logged for incoming and outgoing messages using the DBus::Type system. The MethodCallIdentifier and MethodCallParameters types are now simply known as Identifier and Paramaeters, since they are used with other messages than MethodCall as well. MethodCallParametersIn is now the non-const part of the Parameters type. Signed-off-by: Heiko Hund <heiko@openvpn.net>

Convert to use functionality from the new DBus::Type system. Signed-off-by: Heiko Hund <heiko@openvpn.net>

There's specialized functions for sending authentication protocol commands and DBus messages. Messages can transport file descriptors as a side load in cmsg'es. All is pretty straight forward (if you also consider cmsg that). Signed-off-by: Heiko Hund <heiko@openvpn.net>

The class now implements the complete state machine for the DBus authentication protocol and handles all commands. It's works completely async. With little work it should be doable to subclass different auth protocols from this. However, I'm not sure if there's need for more than what has been there before, so I left it as it is for now. Signed-off-by: Heiko Hund <heiko@openvpn.net>

Sending and receiving of messages is now done asyncronously. In the receive loop, we first peek at the message to determine its size and the receive it in one go including file descriptors, potentially. Received messages are dispatched to their registered handlers, a.k.a completion tokens, to be dealt with. Added the DBus::StoredToken helper class to keep a hold of the callers completion token while we're waiting for a message event it receives to happen, as ASIO itself currently does not have support for that. Signed-off-by: Heiko Hund <heiko@openvpn.net>

This is the class to tie all things together. It replaces DBus::Native with pretty much comparable functionality. Just think the name suits better. Offers an interface to connect to DBus and deal with messages on a low level. There are also helper functions for DBus interfaces and messages. Signed-off-by: Heiko Hund <heiko@openvpn.net>

They have been converted 1:1 even if the functionality doesn't make much sense anymore. To be extended at a later time. Signed-off-by: Heiko Hund <heiko@openvpn.net>

Get rid of boost and pthreads. Signed-off-by: Heiko Hund <heiko@openvpn.net>

Signed-off-by: Heiko Hund <heiko@openvpn.net>

BusName, InterfaceName and ObjectPath are not needed in all messages and thus can be left undefined for those. This can be achieved by default constructing them. Added an operator bool() to test for this. Also support ostream'ing names via operator const char*(). Signed-off-by: Heiko Hund <heiko@openvpn.net>

Since each represents one flag value, it's a bit easier on the eye. Signed-off-by: Heiko Hund <heiko@openvpn.net>

Signed-off-by: Heiko Hund <heiko@openvpn.net>

d12fk added 2 commits April 14, 2022 13:29

update catch2 to version 2.13.7

6bf0af0

Signed-off-by: Heiko Hund <heiko@openvpn.net>

update pkg-config file

01e1118

* remove quotes from name (not needed) * while at it rephrase * remove empty Requires Signed-off-by: Heiko Hund <heiko@openvpn.net>

d12fk marked this pull request as draft April 14, 2022 12:34

d12fk self-assigned this Apr 14, 2022

d12fk mentioned this pull request Apr 14, 2022

Feedback dbus-asio/dbus-asio#13

Open

d12fk force-pushed the async_api branch 4 times, most recently from 7403650 to 0e4bdec Compare April 15, 2022 00:48

d12fk commented Apr 15, 2022

View reviewed changes

d12fk force-pushed the async_api branch 2 times, most recently from 7d78237 to 0e4bdec Compare April 15, 2022 20:53

d12fk added 2 commits April 19, 2022 13:19

d12fk force-pushed the async_api branch 4 times, most recently from d2827d4 to 79ea89a Compare April 23, 2022 09:52

d12fk added 10 commits April 23, 2022 12:18

add option to use standalone ASIO

ba23113

Let the user decide which version of ASIO to build against. Users of dbus-asio need to link against the same version of asio, so this adds some flexibility if they can't or don't want to switch to boost. Signed-off-by: Heiko Hund <heiko@openvpn.net>

add DBus::Error type as a generic error wrapper

c06503d

This error abstraction is able to hold either a error_code as used by asio, or a DBus::Message::Error as received from dbus. Signed-off-by: Heiko Hund <heiko@openvpn.net>

add support for the UnixFd DBus type

0bd6757

DBus has support for passing file descriptors between processes via the Unix sockets. This adds the respective type and prepares buffer and streams to handle such FDs when sending and receiving messages. Signed-off-by: Heiko Hund <heiko@openvpn.net>

use Type::Signature in Introspectable

62caac1

Convert to use functionality from the new DBus::Type system. Signed-off-by: Heiko Hund <heiko@openvpn.net>

d12fk force-pushed the async_api branch 2 times, most recently from cd0fff4 to 30d47b3 Compare April 23, 2022 10:52

d12fk force-pushed the async_api branch 6 times, most recently from b0639be to 3b413f9 Compare April 23, 2022 11:39

d12fk added 10 commits May 16, 2022 15:47

convert example programs to use the new API

ad41751

They have been converted 1:1 even if the functionality doesn't make much sense anymore. To be extended at a later time. Signed-off-by: Heiko Hund <heiko@openvpn.net>

remove no longer needed dependencies

17b8560

Get rid of boost and pthreads. Signed-off-by: Heiko Hund <heiko@openvpn.net>

also build asio standalone in github action

ac36dfa

Signed-off-by: Heiko Hund <heiko@openvpn.net>

use singular for enum RequestNameFlag

2008378

Since each represents one flag value, it's a bit easier on the eye. Signed-off-by: Heiko Hund <heiko@openvpn.net>

add convenience connect API and connected() method

2c9c335

Signed-off-by: Heiko Hund <heiko@openvpn.net>

add method to cancel receiving signal(s)

91345d2

Signed-off-by: Heiko Hund <heiko@openvpn.net>

add variadic template, copy and move c'tors to Parameters

01120f1

Signed-off-by: Heiko Hund <heiko@openvpn.net>

move more initialization into Message c'tor

2391617

Signed-off-by: Heiko Hund <heiko@openvpn.net>

d12fk force-pushed the async_api branch from 3b413f9 to 2391617 Compare May 16, 2022 13:49

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Async API review#1

Async API review#1
d12fk wants to merge 24 commits intomasterfrom
async_api

d12fk commented Apr 14, 2022

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d12fk commented Apr 14, 2022

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