Overview

Relevant source files

• README.md
• libs/scrap/src/common/record.rs
• src/client.rs
• src/client/io_loop.rs
• src/flutter.rs
• src/flutter_ffi.rs
• src/server/connection.rs
• src/ui/header.tis
• src/ui/remote.rs
• src/ui/remote.tis
• src/ui_session_interface.rs

RustDesk is a cross-platform remote desktop application written in Rust. It provides peer-to-peer remote desktop access with support for screen sharing, remote control, file transfer, audio streaming, and terminal access. The system operates with a multi-process architecture and supports connections through direct peer-to-peer (with NAT traversal) or via relay servers.

This page provides a high-level overview of the entire RustDesk codebase, its architecture, and how major components interact. For detailed information about specific subsystems:

• Connection handling details: see Connection Management
• UI implementation: see User Interface
• Service implementations: see Core Services
• Platform-specific code: see Platform Services
• Build processes: see Build System

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System Purpose

RustDesk implements a complete remote desktop solution with the following capabilities:

Capability	Description
Remote Desktop Control	Full keyboard/mouse control of remote systems with video streaming
File Transfer	Bidirectional file transfer with resume support
Port Forwarding	TCP tunneling for accessing remote services
Audio Streaming	Voice calls and remote audio playback
Terminal Access	Remote shell access with PTY support
Camera Viewing	Remote camera access
NAT Traversal	UDP/TCP hole punching for direct peer-to-peer connections

The codebase is structured to support multiple UI frameworks (Flutter primary, Sciter deprecated), multiple operating systems (Windows, Linux, macOS, Android, iOS), and various hardware codec implementations.

Sources: README.md20-28 src/server/connection.rs1-305 src/client.rs1-100

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Core Architecture Components

Sources: README.md159-171 src/flutter_ffi.rs1-100 src/client.rs184-230 src/server/connection.rs349-489

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Multi-Process Architecture

RustDesk uses separate processes for privilege separation and stability:

Process Responsibilities:

Process	Flag	Primary Role	Key Files
Main	--default	UI, user input, client connections	src/main.rs flutter/
Server	--server	Accept incoming connections, manage sessions	src/server/connection.rs350-489
CM	--cm	Connection manager UI, file operations	src/flutter.rs src/ui_cm_interface.rs

The server process spawns a Connection instance for each incoming remote client. Each Connection manages its own service subscriptions (video, audio, input, clipboard).

Sources: src/server/connection.rs207-305 src/ipc.rs src/main.rs

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Connection Establishment Flow

RustDesk establishes connections through a multi-step process involving NAT traversal:

Key Classes in Connection Flow:

• Client::start() in src/client.rs188-230 - Initiates outbound connections
• Client::_start_inner() in src/client.rs366-627 - NAT traversal and relay logic
• Connection::start() in src/server/connection.rs350-489 - Handles incoming connections
• ConnInner in src/server/connection.rs126-130 - Represents connection endpoint for services
• Subscriber trait for service pub-sub pattern

Sources: src/client.rs188-627 src/server/connection.rs126-489 src/rendezvous_mediator.rs

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Service Architecture

Services implement a publish-subscribe pattern where connections subscribe to needed services:

Service Names (Constants):

• video_service::NAME - Video frame streaming
• input_service::NAME - Input event processing
• audio_service::NAME - Audio streaming
• clipboard_service::NAME - Text clipboard sync
• clipboard_service::FILE_NAME - File clipboard (Windows/Linux)
• NAME_CURSOR - Cursor position updates
• NAME_POS - Window position updates

Sources: src/server/connection.rs593-663 src/server/video_service.rs src/server/input_service.rs

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Flutter-Rust Integration

The Flutter UI communicates with the Rust core through FFI:

Key FFI Functions:

• session_start() in src/flutter_ffi.rs178-184 - Start a session
• session_send_mouse() - Send mouse events
• session_input_key() in src/flutter_ffi.rs628-642 - Send keyboard input
• session_login() in src/flutter_ffi.rs232-242 - Authenticate connection
• main_get_option() / main_set_option() in src/flutter_ffi.rs945-1017 - Configuration

The FlutterHandler implements InvokeUiSession trait to push events back to Flutter via StreamSink<EventToUI>.

Sources: src/flutter_ffi.rs1-200 src/flutter.rs200-450 src/ui_session_interface.rs1-100

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Data Flow: Video Streaming

Video frames flow from screen capture through encoding to the client UI:

Key Components:

• video_service::run() spawns per-display capture threads
• Capturer implementations in libs/scrap/src/ for each platform
• Encoder in libs/scrap/src/common/codec.rs
• VideoFrameController in src/server/video_service.rs manages frame pacing
• Decoder::handle_video_frame() in client processes frames
• FlutterHandler::on_rgba() or texture rendering pushes to UI

Sources: src/server/video_service.rs libs/scrap/src/common/codec.rs src/client/io_loop.rs src/flutter.rs240-450

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Message Protocol

Communication uses Protocol Buffers defined in hbb_common::message_proto:

Message Type	Purpose	Key Fields
LoginRequest	Initial authentication	username, password, my_id, option
LoginResponse	Auth result	error, peer_info
VideoFrame	Video data	vp8s/vp9s/av1s/h264s/h265s union
CursorPosition	Cursor location	x, y
CursorData	Cursor image	id, hotx, hoty, width, height, colors
MouseEvent	Mouse input	mask, x, y, modifiers
KeyEvent	Keyboard input	chr, down, press, mode, modifiers
Clipboard	Clipboard sync	compress, content or cliprdr
FileAction	File operations	send/receive/remove_file/all_files union
Misc	Control messages	audio_format/chat_message/switch_display union

Messages are sent via Stream::send(&Message) and received via Stream::next().

Sources: hbb_common/protos/message.proto src/server/connection.rs768-1500 src/client/io_loop.rs225-355

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Configuration System

RustDesk uses a multi-layered configuration system:

Configuration Storage:

• LocalConfig stored in {APP_DIR}/config/RustDesk.toml (hbb_common/src/config.rs)
• PeerConfig stored in {APP_DIR}/config/peers/{peer_id}.toml
• Keys defined as constants in hbb_common/src/config/keys.rs

Sources: hbb_common/src/config.rs src/client.rs44-73 src/ui_session_interface.rs199-650

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Summary

RustDesk implements a sophisticated remote desktop system with:

1. Multi-process architecture for security and stability
2. Flexible UI layer supporting Flutter (primary) and Sciter (deprecated)
3. Service-oriented design with pub-sub patterns for video, audio, input, and clipboard
4. NAT traversal with UDP/TCP hole punching and relay fallback
5. Cross-platform support via platform abstraction layers
6. Multiple transport protocols (TCP, UDP, KCP, WebSocket)
7. Hardware and software codecs for video encoding/decoding

The architecture prioritizes performance (hardware encoding, efficient IPC), security (process isolation, encryption), and portability (platform abstraction, multiple UI frameworks).

For deeper understanding of specific subsystems, refer to the linked sections at the top of this page.

Sources: README.md1-183 src/server/connection.rs1-305 src/client.rs1-230 src/flutter_ffi.rs1-200