The Servo Browser Engine
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atbrakhi 71d97bd935
Devtools: send error replies instead of ignoring messages (#37686)
Client messages, which are always requests, are dispatched to Actor
instances one at a time via Actor::handle_message. Each request must be
paired with exactly one reply from the same actor the request was sent
to, where a reply is a message with no type (if a message from the
server has a type, it’s a notification, not a reply).

Failing to reply to a request will almost always permanently break that
actor, because either the client gets stuck waiting for a reply, or the
client receives the reply for a subsequent request as if it was the
reply for the current request. If an actor fails to reply to a request,
we want the dispatcher (ActorRegistry::handle_message) to send an error
of type `unrecognizedPacketType`, to keep the conversation for that
actor in sync. Since replies come in all shapes and sizes, we want to
allow Actor types to send replies without having to return them to the
dispatcher.

This patch adds a wrapper type around a client stream that guarantees
request/reply invariants. It allows the dispatcher to check if a valid
reply was sent, and guarantees that if the actor tries to send a reply,
it’s actually a valid reply (see ClientRequest::is_valid_reply). It does
not currently guarantee anything about messages sent via the TcpStream
released via ClientRequest::try_clone_stream or the return value of
ClientRequest::reply. We also send `unrecognizedPacketType`,
`missingParameter`, `badParameterType`, and `noSuchActor` messages per
the
[protocol](https://firefox-source-docs.mozilla.org/devtools/backend/protocol.html#error-packets)
[docs](https://firefox-source-docs.mozilla.org/devtools/backend/protocol.html#packets).

Testing: automated tests all pass, and manual testing looks ok
Fixes: #37683 and at least six bugs, plus one with a different root
cause, plus three with zero impact

---------

Signed-off-by: atbrakhi <atbrakhi@igalia.com>
Signed-off-by: Delan Azabani <dazabani@igalia.com>
Co-authored-by: delan azabani <dazabani@igalia.com>
Co-authored-by: Simon Wülker <simon.wuelker@arcor.de>
Co-authored-by: the6p4c <me@doggirl.gay>
2025-07-07 12:40:44 +00:00
.cargo Move various reflector types and traits to script_bindings (#35279) 2025-02-04 06:58:08 +00:00
.github OHOS CI: Robustness of speedometer (#37830) 2025-07-02 14:48:47 +00:00
.vscode use ruff rather than flake8 for python code linting (#37045) 2025-05-24 14:19:47 +00:00
components Devtools: send error replies instead of ignoring messages (#37686) 2025-07-07 12:40:44 +00:00
docs Update in-tree docs to point to the new book (#32743) 2024-07-09 15:42:00 +00:00
etc Support WPT subsuites in agregating and flake detection (#37584) 2025-07-04 16:58:42 +00:00
ports/servoshell Move webdriver actions commands to servoshell (#37669) 2025-07-04 16:29:38 +00:00
python Support WPT subsuites in agregating and flake detection (#37584) 2025-07-04 16:58:42 +00:00
resources tests: Use Ahem font provided by WPT harness. (#37054) 2025-06-09 08:13:05 +00:00
support libservo|compositor: Have scroll offset directionality match that of WebRender and the web (#37752) 2025-07-03 13:04:06 +00:00
tests Implement initial version of ReportingObserver (#37905) 2025-07-07 10:43:30 +00:00
third_party Fix the native-bluetooth feature on macOS (#37476) 2025-06-16 06:58:08 +00:00
.gitattributes openharmony: add servoshell for ohos (#33295) 2024-09-20 08:20:27 +00:00
.gitignore Add justfile to gitignore (#37621) 2025-06-23 02:37:04 +00:00
.mailmap Update Tetsuharu OHZEKI's entry in mailmap 2019-11-15 00:46:45 +09:00
.python-version Set python version to 3.11 (#34707) 2024-12-19 18:42:36 +00:00
Cargo.lock build(deps): bump cc from 1.2.27 to 1.2.28 (#37884) 2025-07-04 17:23:53 +00:00
Cargo.toml Send WillNavigate earlier during navigation startup (#37778) 2025-07-05 11:35:37 +00:00
CODE_OF_CONDUCT.md Clarify the Code of Conduct (closes servo/servo.org#164) (#32835) 2024-07-23 09:12:03 +00:00
CONTRIBUTING.md Update in-tree docs to point to the new book (#32743) 2024-07-09 15:42:00 +00:00
deny.toml servoshell: Enable accesskit integration. (#37519) 2025-06-25 03:52:49 +00:00
Info.plist remove bhtml 2018-02-11 08:02:39 +01:00
LICENSE Update MPL license to https (part 1) 2018-11-19 14:46:43 +01:00
LICENSE_WHATWG_SPECS Add license for WHATWG specifications in code (#36282) 2025-04-03 04:33:06 +00:00
mach Mergeruff.toml into pyproject.toml (#37741) 2025-07-04 12:21:48 +00:00
mach.bat Mergeruff.toml into pyproject.toml (#37741) 2025-07-04 12:21:48 +00:00
PULL_REQUEST_TEMPLATE.md Use a simpler GitHub pull request template (#36203) 2025-03-30 10:14:13 +00:00
pyproject.toml Mergeruff.toml into pyproject.toml (#37741) 2025-07-04 12:21:48 +00:00
README.md Link to the Zulip and project repo in README (#37134) 2025-05-26 15:51:50 +00:00
rust-toolchain.toml Unsimplify rust-toolchain.toml by adding clippy and rustfmt (#37028) 2025-05-16 17:04:27 +00:00
rustfmt.toml Update rustfmt to the 2024 style edition (#35764) 2025-03-03 11:26:53 +00:00
SECURITY.md docs(security): avoid possible misconception in the security policy (#37032) 2025-05-16 21:27:42 +00:00
servo-tidy.toml Implement basics of link preloading (#37036) 2025-05-29 11:26:27 +00:00
servobuild.example Fix DBus warning when running mach (#37818) 2025-07-02 23:17:01 +00:00
shell.nix Fix DBus warning when running mach (#37818) 2025-07-02 23:17:01 +00:00
taplo.toml Format toml files (#30112) 2023-08-17 15:07:43 +00:00
uv.toml uv: Use native-tls (#36564) 2025-04-16 11:47:49 +00:00

The Servo Parallel Browser Engine Project

Servo is a prototype web browser engine written in the Rust language. It is currently developed on 64-bit macOS, 64-bit Linux, 64-bit Windows, 64-bit OpenHarmony, and Android.

Servo welcomes contribution from everyone. Check out:

Coordination of Servo development happens:

Getting started

For more detailed build instructions, see the Servo book under Setting up your environment, Building Servo, Building for Android and Building for OpenHarmony.

macOS

  • Download and install Xcode and brew.
  • Install uv: curl -LsSf https://astral.sh/uv/install.sh | sh
  • Install rustup: curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
  • Restart your shell to make sure cargo is available
  • Install the other dependencies: ./mach bootstrap
  • Build servoshell: ./mach build

Linux

  • Install curl:
    • Arch: sudo pacman -S --needed curl
    • Debian, Ubuntu: sudo apt install curl
    • Fedora: sudo dnf install curl
    • Gentoo: sudo emerge net-misc/curl
  • Install uv: curl -LsSf https://astral.sh/uv/install.sh | sh
  • Install rustup: curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
  • Restart your shell to make sure cargo is available
  • Install the other dependencies: ./mach bootstrap
  • Build servoshell: ./mach build

Windows

  • Download uv, choco, and rustup
    • Be sure to select Quick install via the Visual Studio Community installer
  • In the Visual Studio Installer, ensure the following components are installed:
    • Windows 10 SDK (10.0.19041.0) (Microsoft.VisualStudio.Component.Windows10SDK.19041)
    • MSVC v143 - VS 2022 C++ x64/x86 build tools (Latest) (Microsoft.VisualStudio.Component.VC.Tools.x86.x64)
    • C++ ATL for latest v143 build tools (x86 & x64) (Microsoft.VisualStudio.Component.VC.ATL)
    • C++ MFC for latest v143 build tools (x86 & x64) (Microsoft.VisualStudio.Component.VC.ATLMFC)
  • Restart your shell to make sure cargo is available
  • Install the other dependencies: .\mach bootstrap
  • Build servoshell: .\mach build

Android

  • Ensure that the following environment variables are set:
    • ANDROID_SDK_ROOT
    • ANDROID_NDK_ROOT: $ANDROID_SDK_ROOT/ndk/26.2.11394342/ ANDROID_SDK_ROOT can be any directory (such as ~/android-sdk). All of the Android build dependencies will be installed there.
  • Install the latest version of the Android command-line tools to $ANDROID_SDK_ROOT/cmdline-tools/latest.
  • Run the following command to install the necessary components:
    sudo $ANDROID_SDK_ROOT/cmdline-tools/latest/bin/sdkmanager --install \
     "build-tools;34.0.0" \
     "emulator" \
     "ndk;26.2.11394342" \
     "platform-tools" \
     "platforms;android-33" \
     "system-images;android-33;google_apis;x86_64"
    
  • Follow the instructions above for the platform you are building on

OpenHarmony

  • Follow the instructions above for the platform you are building on to prepare the environment.
  • Depending on the target distribution (e.g. HarmonyOS NEXT vs pure OpenHarmony) the build configuration will differ slightly.
  • Ensure that the following environment variables are set
    • DEVECO_SDK_HOME (Required when targeting HarmonyOS NEXT)
    • OHOS_BASE_SDK_HOME (Required when targeting OpenHarmony)
    • OHOS_SDK_NATIVE (e.g. ${DEVECO_SDK_HOME}/default/openharmony/native or ${OHOS_BASE_SDK_HOME}/${API_VERSION}/native)
    • SERVO_OHOS_SIGNING_CONFIG: Path to json file containing a valid signing configuration for the demo app.
  • Review the detailed instructions at Building for OpenHarmony.
  • The target distribution can be modified by passing --flavor=<default|harmonyos> to `mach <build|package|install>.