Liyi Meng
a3934cde9a
Three correctness gaps found in code review of the private-loop rewrite, all in how chansrv's thread and the IBus thread interact around `bus`: - xrdp_input_enable() read the shared `bus` pointer with no synchronization at all, despite the IBus thread being free to null it out (disconnect, teardown) at any time - a real use-after-free risk, not just a formality, since this function actively calls methods on it rather than just checking it's non-NULL. Fixed by taking a ref under state_mutex before touching it, and using that local reference for the rest of the call; bus's creation and teardown in xrdp_input_main_loop() now publish/clear the shared pointer under the same lock so the ref-under-lock pattern actually synchronizes against something. - xrdp_input_unicode_init()'s fast path trusted ibus_ready without re-checking the connection. ibus_ready and connection liveness normally change together, but there's a window between the underlying socket actually dying and the "disconnected" signal being dispatched on the IBus thread. A client that reconnects into that window would get a false "unicode input is supported" advertisement it could never actually use. Now double-checks ibus_bus_is_connected() before taking the fast path. - That staleness check can't just flip ibus_ready and fall through to spawning a new thread - the old one may still be alive and about to touch bus/g_engine itself, racing the new thread's own setup. Now asks the stale thread to shut down (g_main_loop_quit, safe to call cross-thread) and waits on the exit condvar before proceeding, so there's never more than one IBus thread alive at a time. Verified: 20 back-to-back xrdp_input_unicode_init() calls on a healthy connection all take the fast path correctly (no spurious thread restarts); 5 kill/restart cycles still show no thread leak; an 18-char rapid-fire send against a real focused GTK entry still lands every character in order with zero drops after these changes. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
xrdp - an open source RDP server
Overview
xrdp provides a graphical login to remote machines using Microsoft Remote Desktop Protocol (RDP). xrdp accepts connections from a variety of RDP clients:
- FreeRDP
- rdesktop
- KRDC
- NeutrinoRDP
- Windows MSTSC (Microsoft Terminal Services Client, aka
mstsc.exe) - Microsoft Remote Desktop (found on Microsoft Store, which is distinct from MSTSC)
Many of these work on some or all of Windows, Mac OS, iOS, and/or Android.
RDP transport is encrypted using TLS by default.
Features
Remote Desktop Access
- Connect to a Linux desktop using RDP from anywhere (requires xorgxrdp Xorg module)
- Reconnect to an existing session
- Session resizing (both on-connect and on-the-fly)
- RDP/VNC proxy (connect to another RDP/VNC server via xrdp)
Access to Remote Resources
- Two-way clipboard transfer (text, bitmap, file)
- Audio redirection (requires to build additional modules)
- Microphone redirection (requires to build additional modules)
- Drive redirection (mount local client drives on remote machine)
Supported Platforms
xrdp primarily targets GNU/Linux operating system. x86 (including x86-64) and ARM processors are most mature architecture to run xrdp on. See also Platform Support Tier.
Some components such as xorgxrdp and RemoteFX codec have special optimization for x86 using SIMD instructions. So running xrdp on x86 processors will get fully accelerated experience.
Quick Start
Most Linux distributions should distribute the latest release of xrdp in their repository. You would need xrdp and xorgxrdp packages for the best experience. It is recommended that xrdp depends on xorgxrdp, so it should be sufficient to install xrdp. If xorgxrdp is not provided, use Xvnc server.
xrdp listens on 3389/tcp. Make sure your firewall accepts connection to 3389/tcp from where you want to access.
Ubuntu / Debian
apt install xrdp
Fedora, RHEL and derivatives
If you're not running Fedora, make sure to enable EPEL packages first.
dnf install epel-release
(All systems) Install xrdp with:-
dnf install xrdp
Compiling
See also https://github.com/neutrinolabs/xrdp/wiki#building-from-sources
Prerequisites
To compile xrdp from the packaged sources, you need basic build tools - a compiler (gcc or clang) and the make program. Additionally, you would need openssl-devel, pam-devel, libX11-devel, libXfixes-devel, libXrandr-devel. More additional software would be needed depending on your configuration.
To compile xrdp from a checked out git repository, you would additionally need autoconf, automake, libtool and pkg-config.
Get the source and build it
If compiling from the packaged source, unpack the tarball and change to the resulting directory.
If compiling from a checked out repository, please make sure you've got the submodules
cloned too (use git clone --recursive https://github.com/neutrinolabs/xrdp)
Then run following commands to compile and install xrdp:
./bootstrap
./configure
make
sudo make install
If you want to use audio redirection, you need to build and install additional pulseaudio modules. The build instructions can be found at wiki.
Directory Structure
xrdp
├── common ······ common code
├── docs ········ documentation
├── fontutils ··· font handling utilities
├── genkeymap ··· keymap generator
├── instfiles ··· installable data file
├── keygen ······ xrdp RSA key pair generator
├── libpainter ·· painter library
├── librfxcodec · RFX codec library
├── libxrdp ····· core RDP protocol implementation
├── m4 ·········· Autoconf macros
├── mc ·········· media center module
├── neutrinordp · RDP client module for proxying RDP connections using NeutrinoRDP
├── pkgconfig ··· pkg-config configuration
├── scripts ····· build scripts
├┬─ sesman ······ session manager for xrdp
|├── chansrv ···· channel server for xrdp
|├── libsesman ·· Code common to sesman and its related executables
|└── tools ······ session management tools for sys admins
├── tests ······· tests for the code
├┬─ tools ······· tools
|└┬─ devel ······ development tools
| ├── gtcp_proxy GTK app that forwards TCP connections to a remote host
| └── tcp_proxy · CLI app that forwards TCP connections to a remote host
├── vnc ········· VNC client module for xrdp
├── vrplayer ···· QT player redirecting video/audio to clients over xrdpvr channel
├── xrdp ········ main server code
├── xrdpapi ····· virtual channel API
├── xrdpvr ······ API for playing media over RDP
└── xup ········· xorgxrdp client module