There are many ways to contribute to Socket2, including (but not limited to) answering questions, adding new features, fixing bugs or expanding the documentation. This document will focus on adding new features and fixing bugs.
If you're adding a new feature please first open an issue laying out what would be added and a design you're proposing. Doing this before actually writing the code will save you time if others suggest improvements to the design. Once there is some consensus on 1) the feature is a good addition to Socket2 and 2) the proposed design is the right one, open a pull request with the changes.
If you're working on fixing a bug please say so on the specific issue so that two people don't work on fixing the same bug. For more complex bugs or fixes please also share your proposed design on the issue tracker, same as for new features.
Once you're working on the code it's useful to understand where the code is (or should) be located, the code structure section describes how the code of Socket2 is organised.
To make sure we don't create the same bug again, or to ensure that new features keep working, please add (regression) test for the changes you've made to the code. The testing section below describes how to run the tests and where to add new tests.
All types and methods that are available on all tier 1 platforms are defined in
the first level of the source, i.e. src/*.rs files. Additional API that is
platform specific, e.g. Domain::VSOCK, is defined in src/sys/*.rs and only
for the platforms that support it. For API that is not available on all tier 1
platforms the all feature is used, to indicate to the user that they're using
API that might is not available on all platforms.
The main Socket type is defined in src/socket.rs with additional methods
defined in the src/sys/*.rs files, as per above. The methods on
Socket are split into multiple impl blocks. The first impl block contains
a collection of system calls for creating and using the socket, e.g.
socket(2), bind(2), listen(2), etc. The other implementation blocks are
for getting and setting socket options on various levels, e.g. SOL_SOCKET,
where each block contains a single level. The methods in these block are sorted
based on the option name, e.g. IP_ADD_MEMBERSHIP rather than
join_multicast_v4. Finally the last block contains platforms specific methods
such as Socket::freebind which is (at the time of writing) only available on
Android, Linux and Fuchsia, which is defined in the src/sys/*.rs files.
Other types are mostly defined in src/lib.rs, except for SockAddr and
SockRef which have their own file. These types follow the same structure as
Socket, where OS specific methods are defined in src/sys/*.rs, e.g.
Type::cloexec.
Testing Socket2 is as simple as running cargo test --all-features.
However Socket2 supports a good number of OSs and features. If you want to
test/check all those combinations it's easier to use the Makefile. Using make test_all it will check all supported OS targets and all combinations of
supported features. Note that this requires cargo-hack and various rustup
targets to be installed. Cargo-hack must be installed manually, the various
targets can be installed automatically using make install_targets (which uses
rustup).
Tests should be added to tests/socket.rs, following (roughly) the same order
in which the methods are defined on a type. At the bottom of this file it has a
macro to create a simple get/set socket option test, more complex API however
needs a manually written test.
Tests that need to use internal API can be defined directly at the bottom of the source file. No need for a test module since we intend on keeping the number of internal tests low.