Nintendo Switch emulator
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comex 8e703e08df Implement SSL service
This implements some missing network APIs including a large chunk of the SSL
service, enough for Mario Maker (with an appropriate mod applied) to connect to
the fan server [Open Course World](https://opencourse.world/).

Connecting to first-party servers is out of scope of this PR and is a
minefield I'd rather not step into.

 ## TLS

TLS is implemented with multiple backends depending on the system's 'native'
TLS library.  Currently there are two backends: Schannel for Windows, and
OpenSSL for Linux.  (In reality Linux is a bit of a free-for-all where there's
no one 'native' library, but OpenSSL is the closest it gets.)  On macOS the
'native' library is SecureTransport but that isn't implemented in this PR.
(Instead, all non-Windows OSes will use OpenSSL unless disabled with
`-DENABLE_OPENSSL=OFF`.)

Why have multiple backends instead of just using a single library, especially
given that Yuzu already embeds mbedtls for cryptographic algorithms?  Well, I
tried implementing this on mbedtls first, but the problem is TLS policies -
mainly trusted certificate policies, and to a lesser extent trusted algorithms,
SSL versions, etc.

...In practice, the chance that someone is going to conduct a man-in-the-middle
attack on a third-party game server is pretty low, but I'm a security nerd so I
like to do the right security things.

My base assumption is that we want to use the host system's TLS policies.  An
alternative would be to more closely emulate the Switch's TLS implementation
(which is based on NSS).  But for one thing, I don't feel like reverse
engineering it.  And I'd argue that for third-party servers such as Open Course
World, it's theoretically preferable to use the system's policies rather than
the Switch's, for two reasons

1. Someday the Switch will stop being updated, and the trusted cert list,
   algorithms, etc. will start to go stale, but users will still want to
   connect to third-party servers, and there's no reason they shouldn't have
   up-to-date security when doing so.  At that point, homebrew users on actual
   hardware may patch the TLS implementation, but for emulators it's simpler to
   just use the host's stack.

2. Also, it's good to respect any custom certificate policies the user may have
   added systemwide.  For example, they may have added custom trusted CAs in
   order to use TLS debugging tools or pass through corporate MitM middleboxes.
   Or they may have removed some CAs that are normally trusted out of paranoia.

Note that this policy wouldn't work as-is for connecting to first-party
servers, because some of them serve certificates based on Nintendo's own CA
rather than a publicly trusted one.  However, this could probably be solved
easily by using appropriate APIs to adding Nintendo's CA as an alternate
trusted cert for Yuzu's connections.  That is not implemented in this PR
because, again, first-party servers are out of scope.

(If anything I'd rather have an option to _block_ connections to Nintendo
servers, but that's not implemented here.)

To use the host's TLS policies, there are three theoretical options:

a) Import the host's trusted certificate list into a cross-platform TLS
   library (presumably mbedtls).

b) Use the native TLS library to verify certificates but use a cross-platform
   TLS library for everything else.

c) Use the native TLS library for everything.

Two problems with option a).  First, importing the trusted certificate list at
minimum requires a bunch of platform-specific code, which mbedtls does not have
built in.  Interestingly, OpenSSL recently gained the ability to import the
Windows certificate trust store... but that leads to the second problem, which
is that a list of trusted certificates is [not expressive
enough](https://bugs.archlinux.org/task/41909) to express a modern certificate
trust policy.  For example, Windows has the concept of [explicitly distrusted
certificates](https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-r2-and-2012/dn265983(v=ws.11)),
and macOS requires Certificate Transparency validation for some certificates
with complex rules for when it's required.

Option b) (using native library just to verify certs) is probably feasible, but
it would miss aspects of TLS policy other than trusted certs (like allowed
algorithms), and in any case it might well require writing more code, not less,
compared to using the native library for everything.

So I ended up at option c), using the native library for everything.

What I'd *really* prefer would be to use a third-party library that does option
c) for me.  Rust has a good library for this,
[native-tls](https://docs.rs/native-tls/latest/native_tls/).  I did search, but
I couldn't find a good option in the C or C++ ecosystem, at least not any that
wasn't part of some much larger framework.  I was surprised - isn't this a
pretty common use case?  Well, many applications only need TLS for HTTPS, and they can
use libcurl, which has a TLS abstraction layer internally but doesn't expose
it.  Other applications only support a single TLS library, or use one of the
aforementioned larger frameworks, or are platform-specific to begin with, or of
course are written in a non-C/C++ language, most of which have some canonical
choice for TLS.  But there are also many applications that have a set of TLS
backends just like this; it's just that nobody has gone ahead and abstracted
the pattern into a library, at least not a widespread one.

Amusingly, there is one TLS abstraction layer that Yuzu already bundles: the
one in ffmpeg.  But it is missing some features that would be needed to use it
here (like reusing an existing socket rather than managing the socket itself).
Though, that does mean that the wiki's build instructions for Linux (and macOS
for some reason?) already recommend installing OpenSSL, so no need to update
those.

 ## Other APIs implemented

- Sockets:
    - GetSockOpt(`SO_ERROR`)
    - SetSockOpt(`SO_NOSIGPIPE`) (stub, I have no idea what this does on Switch)
    - `DuplicateSocket` (because the SSL sysmodule calls it internally)
    - More `PollEvents` values

- NSD:
    - `Resolve` and `ResolveEx` (stub, good enough for Open Course World and
      probably most third-party servers, but not first-party)

- SFDNSRES:
    - `GetHostByNameRequest` and `GetHostByNameRequestWithOptions`
    - `ResolverSetOptionRequest` (stub)

 ## Fixes

- Parts of the socket code were previously allocating a `sockaddr` object on
  the stack when calling functions that take a `sockaddr*` (e.g. `accept`).
  This might seem like the right thing to do to avoid illegal aliasing, but in
  fact `sockaddr` is not guaranteed to be large enough to hold any particular
  type of address, only the header.  This worked in practice because in
  practice `sockaddr` is the same size as `sockaddr_in`, but it's not how the
  API is meant to be used.  I changed this to allocate an `sockaddr_in` on the
  stack and `reinterpret_cast` it.  I could try to do something cleverer with
  `aligned_storage`, but casting is the idiomatic way to use these particular
  APIs, so it's really the system's responsibility to avoid any aliasing
  issues.

- I rewrote most of the `GetAddrInfoRequest[WithOptions]` implementation.  The
  old implementation invoked the host's getaddrinfo directly from sfdnsres.cpp,
  and directly passed through the host's socket type, protocol, etc. values
  rather than looking up the corresponding constants on the Switch.  To be
  fair, these constants don't tend to actually vary across systems, but
  still... I added a wrapper for `getaddrinfo` in
  `internal_network/network.cpp` similar to the ones for other socket APIs, and
  changed the `GetAddrInfoRequest` implementation to use it.  While I was at
  it, I rewrote the serialization to use the same approach I used to implement
  `GetHostByNameRequest`, because it reduces the number of size calculations.
  While doing so I removed `AF_INET6` support because the Switch doesn't
  support IPv6; it might be nice to support IPv6 anyway, but that would have to
  apply to all of the socket APIs.

  I also corrected the IPC wrappers for `GetAddrInfoRequest` and
  `GetAddrInfoRequestWithOptions` based on reverse engineering and hardware
  testing.  Every call to `GetAddrInfoRequestWithOptions` returns *four*
  different error codes (IPC status, getaddrinfo error code, netdb error code,
  and errno), and `GetAddrInfoRequest` returns three of those but in a
  different order, and it doesn't really matter but the existing implementation
  was a bit off, as I discovered while testing `GetHostByNameRequest`.

  - The new serialization code is based on two simple helper functions:

    ```cpp
    template <typename T> static void Append(std::vector<u8>& vec, T t);
    void AppendNulTerminated(std::vector<u8>& vec, std::string_view str);
    ```

    I was thinking there must be existing functions somewhere that assist with
    serialization/deserialization of binary data, but all I could find was the
    helper methods in `IOFile` and `HLERequestContext`, not anything that could
    be used with a generic byte buffer.  If I'm not missing something, then
    maybe I should move the above functions to a new header in `common`...
    right now they're just sitting in `sfdnsres.cpp` where they're used.

- Not a fix, but `SocketBase::Recv`/`Send` is changed to use `std::span<u8>`
  rather than `std::vector<u8>&` to avoid needing to copy the data to/from a
  vector when those methods are called from the TLS implementation.
2023-06-25 12:53:31 -07:00
.ci android: Various fixes for CI. 2023-06-03 00:06:05 -07:00
.github github: Remove release workflow 2023-06-06 15:12:12 -04:00
.reuse android: Various fixes for CI. 2023-06-03 00:06:05 -07:00
CMakeModules android: Use ext-android-bin for external binaries. 2023-06-03 00:06:06 -07:00
dist Update translations (2023-06-01) 2023-06-01 03:01:52 +00:00
externals Merge pull request #10825 from 8bitDream/vcpkg-zlib 2023-06-18 09:43:12 -04:00
hooks chore: make yuzu REUSE compliant 2022-07-27 12:53:49 +02:00
LICENSES android: Various fixes for CI. 2023-06-03 00:06:05 -07:00
src Implement SSL service 2023-06-25 12:53:31 -07:00
.codespellrc codespell: Exclude android resources directory 2023-06-13 02:15:21 +02:00
.gitattributes chore: make yuzu REUSE compliant 2022-07-27 12:53:49 +02:00
.gitignore android: Initialize defaults for each orientations 2023-06-14 16:35:58 -04:00
.gitmodules externals: submodule tzdb_to_nx 2023-06-16 04:15:19 -04:00
CMakeLists.txt Implement SSL service 2023-06-25 12:53:31 -07:00
CONTRIBUTING.md chore: make yuzu REUSE compliant 2022-07-27 12:53:49 +02:00
Doxyfile chore: make yuzu REUSE compliant 2022-07-27 12:53:49 +02:00
LICENSE.txt chore: make yuzu REUSE compliant 2022-07-27 12:53:49 +02:00
README.md Update README.md (Add Android at builds description) (#10586) 2023-06-03 16:29:26 +02:00
vcpkg.json externals: Update vcpkg to 2023.06.17 2023-06-17 21:46:09 -04:00


yuzu
yuzu

yuzu is the world's most popular, open-source, Nintendo Switch emulator — started by the creators of Citra.
It is written in C++ with portability in mind, and we actively maintain builds for Windows, Linux and Android.

Azure Mainline CI Build Status Discord

Compatibility | Development | Building | Download | Support | License

Compatibility

The emulator is capable of running most commercial games at full speed, provided you meet the necessary hardware requirements.

For a full list of games yuzu support, please visit our Compatibility page

Check out our website for the latest news on exciting features, monthly progress reports, and more!

Development

Most of the development happens on GitHub. It's also where our central repository is hosted. For development discussion, please join us on Discord.

If you want to contribute, please take a look at the Contributor's Guide and Developer Information. You can also contact any of the developers on Discord in order to know about the current state of the emulator.

If you want to contribute to the user interface translation project, please check out the yuzu project on transifex. We centralize translation work there, and periodically upstream translations.

Building

Download

You can download the latest releases automatically via the installer on our downloads page.

Support

If you enjoy the project and want to support us financially, check out our Patreon!

Any donations received will go towards things like:

  • Switch consoles to explore and reverse-engineer the hardware
  • Switch games for testing, reverse-engineering, and implementing new features
  • Web hosting and infrastructure setup
  • Software licenses (e.g. Visual Studio, IDA Pro, etc.)
  • Additional hardware (e.g. GPUs as-needed to improve rendering support, other peripherals to add support for, etc.)

If you wish to support us a different way, please join our Discord and talk to bunnei. You may also contact: donations@yuzu-emu.org.

License

yuzu is licensed under the GPLv3 (or any later version). Refer to the LICENSE.txt file.