desktop-companion

Project primer

desktop-companion — NinjaRMM Desktop Companion (review primer)

Cross-platform (Windows x86/x64/ARM64, macOS x64/ARM64) C++/Qt system-tray desktop client
(Qt Quick/QML UI + Qt Network/NetworkAuth). Authenticates MSPs/end-users via OAuth2 + PKCE
against the NinjaRMM cloud API, shows a managed-device list, and launches remote-access sessions
(RDP, TeamViewer, Splashtop, NinjaConnect, web terminal, PowerShell). WiX MSI on Windows.

Architecture (durable map)

• REST API wrappers per endpoint group + an HTTP worker (QNetworkAccessManager) + response

deserialization into value-object models.

• OAuth2 authorization-code + PKCE flow with a local loopback reply handler; a user-session

singleton owning token lifecycle (acquire/refresh/revoke) + environment (prod/non-prod).

• Platform keychain manager for token storage; QML UI talking to C++ singletons via context

properties; dashboard (device list + self-update), remote-access dispatcher, settings
(QSettings + autostart), single-instance guard (shared memory), Crashpad/Sentry.

What matters most when reviewing here (durable risk areas)

• OAuth2 / token handling. PKCE state + code-verifier generation, callback state validation,

keychain storage, refresh/expiry. Bugs leak or stale credentials.

• Self-update. Download an installer → verify hash → run. Integrity must gate execution;

path-handling / TOCTOU gaps are critical.

• Remote-session launch. URLs/process args are built from API-sourced device data —

URL/argument injection if unsanitised.

• Cryptographic randomness. OAuth state/verifier and single-instance keys must use a CSPRNG,

not a non-cryptographic RNG — verify RNG strength.

• API error handling. Silently swallowed 401/403 leaves a stale session active.
• Cross-platform. Windows/macOS branches (settings, autostart, log paths, build) — validate both.
• QML↔C++ boundary. Context-property names/types are stringly-typed contracts; mismatches

crash the engine.

Security-sensitive zones

Token acquisition/storage/refresh + keychain (a plaintext fallback would be severe); the OAuth2
loopback redirect + PKCE/state validation; self-update integrity + download destination; remote-
launch URL/arg construction from API data; logs must never contain tokens/credentials.

Compatibility surfaces (contracts that must not silently break)

• The NinjaRMM REST API shapes the models deserialize (tolerant parsing can hide breakage).
• OAuth2 endpoint paths + per-environment client IDs.
• QSettings keys + the Windows autostart registry entry (renames silently drop user settings).
• The WiX MSI UpgradeCode (must never change — changing it breaks major-upgrade detection).
• QML/C++ context-property names.

Conventions & gotchas

• Qt version — the ONE exception to "Qt5 is retired". Unlike the ncpeer/nmsnj family (all

migrated to Qt6), desktop-companion may still target/support Qt5, so — uniquely for this repo —
a change that breaks Qt5 build/compatibility CAN be a legitimate finding. Confirm the actual Qt
version in the build files before relying on either assumption; do not blanket-apply the
Qt6-only rule here.

• Singletons via static-local accessors; background-worker signals need queued connections.
• A hidden QA mode (multi-click) enables non-production environments — ensure it can't trigger in prod.
• Crash symbols / Sentry DSN are baked at build time via vcpkg; a missing vcpkg root yields a

silent empty-libs build.

_Orientation only — verify current specifics in the code; this describes durable architecture &
risk areas, not a snapshot._

Ecosystem map

NinjaRemote / NinjaOne project ecosystem (relationship map)

How the monitored repos relate — so a change in one repo is reviewed with its blast
radius in mind (a change upstream of ncpeer can break ncpeer even if it looks local).
Orientation only; verify specifics in code.

NinjaRemote product

• ncpeer — the remote-desktop client/agent (streamer host + player viewer). The hub.
• ncrp — the server/relay component NinjaRemote peers connect through; ncpeer ⇄ ncrp

speak the NCRP wire protocol (protocol/format changes must stay compatible across
client and server versions).

• ncinstaller — installs the ncpeer player onto end machines.
• qclauncher — bootstraps/launches an ncpeer quick-connect session.

Cloud-side relays of the ninja-remote system (AWS-hosted, Python/Go)

• websocket-switch — generic WebSocket pairing relay: two clients join with signed

URLs, it pairs them and forwards frames verbatim. Signed join URLs are minted by the
Ninja backend — the signature scheme is a backend⇄relay contract, and the frame
semantics are a peer⇄peer contract.

• file-transfer-service — the same pairing idea over plain HTTP for file transfer:

a signed upload leg streams to a signed download leg through memory (never stored).
Two parallel implementations (Python ftsv2/ + Go fts_go/) must stay behaviorally
identical; the URL/signature scheme is shared-family with websocket-switch.
NinjaRemote file-transfer features ride on these relays when peers can't go direct.

Pulled INTO ncpeer (and sometimes nmsnj) — upstream of the products

• nccommon — shared C++ library; a submodule of BOTH ncpeer and nmsnj. An API/ABI

or behaviour change here affects both consumers.

• nr-i18n — localization resources; a submodule of ncpeer.
• nrvirtdisplay — Windows virtual-display driver used by ncpeer.
• nrvusb — virtual-USB driver used by ncpeer.
• ncpeer_vcpkg — the pinned/patched dependency set (vcpkg fork) that **ncpeer and nmsnj

build against**. A dependency bump changes what those products link (security/ABI/build).

• ncpeer_qt6win7 — patched Qt6 (QtBase) for legacy-OS support, delivered to the clients

through the ncpeer_vcpkg overlay.

Largely independent

• nmsnj — network-management delegate (talks to the Ninja Backend over WAMP/RPC);

shares nccommon and ncpeer_vcpkg with ncpeer.

• ninjaflow — packet-capture library + agent (a distinct network-telemetry product, NOT

part of the remote-desktop family). Runs as a child process of the NinjaRMM agent (the
parent owns install/upgrade/policy/launch); NinjaFlow owns the CLI contract, config schema,
credential precedence, DB schema/migrations, and exit-code meanings the parent consumes —
those are cross-process contracts. Submits telemetry to the Ninja Backend. Shares no code with
ncpeer/nmsnj; adjacent to nmsnj only in domain (network), not in implementation.

• desktop-companion — internal companion app; mostly standalone.
• spaceship — AppSec SBOM-ingestion backend (Python/Flask). A distinct security product,

not part of any product's build. It consumes the SBOMs the other products' pipelines emit
(Ninja-Remote/ncpeer, NMS/nmsnj, NinjaFlow all appear in its scope maps), scans them for CVEs
and files Jira issues — a downstream *security-scanning* relationship, not a code dependency.
Shares no code with the others; has its own DB/schema and a toolbox submodule.

• ssh-pam-ninja — SSH one-time-password PAM gatekeeper (Linux C). A standalone

authentication component: its pam_ninja.so gates SSH reverse-tunnel access into
Ninja infrastructure with a time-based OTP. Shares no code with the other repos; its
blast radius is operational (who can SSH-tunnel into hosts), not code-level. The client OTP
generators and the module must agree on the OTP scheme + shared secret.

Review implications

• Reviewing nccommon / nr-i18n / nrvirtdisplay / nrvusb / ncpeer_vcpkg / ncpeer_qt6win7:

these are *upstream* of ncpeer (and nccommon/vcpkg also of nmsnj) — weigh the consumer
side: API/ABI compatibility, build impact, and cross-platform reach.

• Reviewing ncpeer or ncrp: the NCRP wire protocol between them is a cross-version

contract.