Initial commit: hello-agent — headless RustDesk-protocol-compatible Windows agent

A single-binary, Flutter-free remote-support agent that speaks the stock
RustDesk wire protocol. Designed for one-line MDM deployment against a
self-hosted rustdesk-server: a supporter using the unmodified rustdesk.exe
client connects, the controlled-side user gets a native Win32 approval
prompt, click Yes / No.

CLI surface

    hello-agent.exe --install                # register + start service
    hello-agent.exe --uninstall              # stop, delete, clean up
    hello-agent.exe --config <BLOB>          # admin-UI deploy string
    hello-agent.exe --install --config <BLOB>   # MDM one-liner

--config accepts both forms emitted by the rustdesk-server admin UI: the
reversed-base64 deploy string and the host=,key=,api=,relay= filename
form. Decoded via the upstream custom_server module, persisted via
hbb_common::config::Config::set_option.

Architecture

    --service runs as a Session 0 LocalSystem service. It polls
    WTSGetActiveConsoleSessionId and (re)spawns hello-agent.exe --server
    into the active console session via librustdesk::platform::run_as_user,
    handling the Session 0 → user-session token impersonation.

    --server is the worker. It boots three concurrent components:
      1. cm_popup: an IPC listener on the rustdesk `_cm` named pipe
      2. librustdesk::start_server(true, false): the upstream protocol
         stack — rendezvous mediator, NAT punch, IPC server, screen
         capture, login validation, hbbs_http heartbeat / sysinfo sync
      3. (implicit) ApproveMode::Click is pinned in config, so every
         incoming connection routes through cm_popup

The popup mechanism reuses an existing upstream contract without any
patches to the protocol code: when a peer connects with no password,
Connection::start in the upstream code calls try_start_cm_ipc, which
ipc::connect-s the `_cm` pipe before falling back to spawning a Flutter
CM child. Since cm_popup is up first, step 1 succeeds; we read the
Data::Login{authorized:false} frame, show MessageBoxTimeoutW (Yes/No,
60s, top-most, system-modal), and reply Data::Authorize or Data::Close.

Source tree

    src/main.rs             CLI dispatcher + run_server() composition
    src/cli.rs              hand-rolled argv parser + unit tests
    src/service.rs          windows-service install/uninstall/dispatcher
    src/config_import.rs    --config blob decoding + persistence
    src/cm_popup.rs         _cm IPC listener + Win32 approval dialog

Vendoring

The upstream RustDesk crate is vendored under vendor/rustdesk/ — full
workspace including libs/{hbb_common, scrap, enigo, clipboard,
virtual_display, remote_printer}. This makes the build self-contained
(no submodules, no sibling-repo checkout in CI) and gives us freedom to
fork in a different direction later. Excluded from the vendor: .git,
target/, flutter/, appimage/, flatpak/, fastlane/, docs/, examples/,
ci/, build.py, Dockerfile, upstream README/CLAUDE/AGENTS/GEMINI.

One local divergence vs. upstream: vendor/rustdesk/src/lib.rs flips
`mod custom_server` → `pub mod custom_server` so config_import.rs can
call get_custom_server_from_string without going through the
ui_interface shim. Documented in README.md → "Re-syncing the vendored
copy".

CI

.gitea/workflows/build-windows.yml builds on a self-hosted Windows
runner with Rust 1.75, LLVM 15.0.6 (libclang for bindgen via libvpx-sys),
and a vcpkg cache. The vendored vcpkg.json drives x64-windows-static
deps. The workflow stages the resulting hello-agent.exe into
SignOutput\, reports authenticode signing status (warns on unsigned),
and uploads as artifact. ~15 min full build, faster on incremental.

Out of scope for this commit: Linux/macOS builds, code signing, MSI
packaging, coexistence with stock rustdesk on the same box (currently
shares the RustDesk APP_NAME and config dir).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Cargo.toml

@@ -0,0 +1,62 @@
+[package]
+name = "hello-agent"
+version = "0.1.0"
+edition = "2021"
+rust-version = "1.75"
+description = "Headless RustDesk-protocol-compatible support agent for Windows"
+publish = false
+
+[[bin]]
+name = "hello-agent"
+path = "src/main.rs"
+
+# The full RustDesk protocol stack is vendored under `vendor/rustdesk/`.
+# We consume it as a path dependency on the `librustdesk` crate (the rlib
+# crate-type in its Cargo.toml's [lib] section is what makes this work).
+#
+# We deliberately turn off rustdesk's `flutter` feature: we don't ship the
+# Flutter UI. We keep `hwcodec` for parity with the upstream Windows build
+# and `vram` for hardware-accelerated encoding paths.
+[dependencies]
+# The vendored rustdesk crate's [package] name is "rustdesk" but its [lib]
+# name is "librustdesk". `package = "rustdesk"` aliases it so we can keep
+# `use librustdesk::…` in source.
+librustdesk = { package = "rustdesk", path = "vendor/rustdesk", default-features = false, features = ["use_dasp", "hwcodec", "vram"] }
+hbb_common  = { path = "vendor/rustdesk/libs/hbb_common" }
+
+tokio       = { version = "1", features = ["rt-multi-thread", "macros", "sync", "time", "io-util"] }
+log         = "0.4"
+env_logger  = "0.10"
+anyhow      = "1"
+
+[target.'cfg(target_os = "windows")'.dependencies]
+windows-service = "0.6"
+winapi          = { version = "0.3", features = ["winuser", "wtsapi32", "processthreadsapi", "synchapi", "handleapi", "winbase"] }
+winreg          = "0.11"
+
+# Embed the icon and EXE metadata via the Windows resource compiler.
+# Same crate (and version) the vendored rustdesk uses for its own icon —
+# keeping them in lockstep avoids a duplicate `winres` in Cargo.lock.
+#
+# Unconditional rather than target-gated: build.rs runs on the *host* and
+# decides via `CARGO_CFG_TARGET_OS` whether the target is Windows. A
+# host-conditional build-dep would hide winres on a Linux/macOS host even
+# when cross-compiling to Windows.
+[build-dependencies]
+winres = "0.1"
+
+# Match upstream's release profile so the resulting binary has the same
+# stripping / LTO behavior. Diverging here would surprise CI.
+[profile.release]
+lto = true
+codegen-units = 1
+panic = "abort"
+strip = true
+
+# Mirror the [patch.crates-io] from the vendored rustdesk Cargo.toml. Cargo
+# only honors [patch] at the *outermost* workspace root, so we have to
+# repeat it here. (The Linux-only libxdo-sys-stub avoids requiring libxdo
+# on the build host; on Windows it's conditionally compiled out anyway, but
+# keeping the patch makes a future Linux build configuration easier.)
+[patch.crates-io]
+libxdo-sys = { path = "vendor/rustdesk/libs/libxdo-sys-stub" }