Restore full Remote Play Together on current Steam builds (invite and control)

[okabeeer]

Restore full Remote Play Together on current Steam builds (invite and control)

On today's Steam client, stock RemotePlayWhatever has two problems: it crashes on some builds, and even when it doesn't, invited friends can only watch — they never get control and never show up in the overlay's player list. This PR fixes both, so a guest can actually join and play, and adds a small window to hand each guest keyboard / mouse / controller individually (and take it back).

It's three self-contained commits so you can take them separately if you'd rather:

1. Resolve internal client interfaces by method name — the crash fix.
2. Add per-friend Remote Play Together control roster — the "guests can actually play" fix + UI.
3. Make group creation and invites asynchronous — polish so the UI never freezes.

---

1. Crash fix — resolve internal interfaces by method name

IClientRemoteClientManager is an undocumented interface, and Valve keeps adding Remote Play methods to it between Steam client builds. A C++ virtual call compiles to a fixed vtable index taken from the declaration order in the OpenSteamworks header. So the moment a real Steam build no longer matches that order, every call after the inserted method lands on the wrong function, gets the wrong arguments, and crashes the client. This is the recurring "it worked before, now it crashes after a Steam update" report.

The fix: resolve the method indices by name at runtime instead of trusting the header's order. Each Steam client method stub references its own bare name as an ASCII string near the top of the function (Valve's telemetry / profiling scope). The resolver reads the lea reg, [rip+disp32] that loads that string, builds a name -> vtable-index map, and calls through the resolved index. Calls then self-adapt to whatever build is installed.

• Pure x86-64 machine-code matching, and the name string is present in both steamclient64.dll (PE, Windows) and steamclient.so (ELF, Linux — incl. Steam Deck), so the same path works on every target this project builds for.
• Module bounds via the OS loader: PE headers + VirtualQuery on Windows; dladdr + dl_iterate_phdr on Linux (already linked through CMAKE_DL_LIBS).
• Deliberately minimal: new header-only ClientVTableByName.h (clientvt::NamedVTable), and only IClientRemoteClientManager is routed through it via a thin CRemoteClientManagerByName proxy. IClientEngine is left exactly as before (stable interface, and its stubs don't embed method-name strings). Existing call sites (RemoteClientManager()->…) compile and read identically. Init() now fails cleanly if a required method can't be resolved instead of calling a wrong slot.
• One wrinkle: a few RCM stubs don't embed their name (CancelRemotePlayInviteAndSession). That method is resolved by anchoring between its two named neighbours (…Create, Cancel, Join…); if the anchors bracket exactly one slot that's Cancel, otherwise it's skipped rather than mis-called.

ABI note: on x86-64 both conventions (Windows x64 and System V) pass this as the first integer argument, so invoking the resolved function pointer with the interface pointer prepended is ABI-identical to the original virtual call. RemotePlayPlayer_t args are forwarded by value with their declared types.

---

2. Guests can actually play — control roster

The root cause of "friends can only watch": stock RPW hardcodes groupID = 1 but never actually creates a Remote Play Together group. On current builds the guest joins the stream but has no real group membership — no input control, and they don't appear in the Shift-Tab player list.

The fix runs the real sequence before inviting: ShowRemotePlayTogetherUI(appId) → poll GetLocalRemotePlayTogetherGroupID while it settles → BCreateRemotePlayGroup() → poll again → then invite with the real group id and a guest id from GetAvailableRemotePlayTogetherGuestID. Control is granted per guest via SetPerUser{Keyboard,Mouse,Controller}InputEnabled, using the exact RemotePlayPlayer_t Steam hands back on the RemoteClientStartStreamSession_t callback, and re-asserted every ~2s so Steam can't silently reset it.

New proxy methods for the above are added to CRemoteClientManagerByName (same name-resolution path as the crash fix, so this stays drift-proof too).

UI: a small ControlFrame window pops up when the first guest connects — one row per guest with their avatar and name and three green/red toggle buttons (Keyboard / Mouse / Controller). Clicking a toggle grants or revokes that peripheral for that guest live. It's plain wxWidgets (core base adv), no new dependencies, hidden until there's someone to show.

---

3. Async invites — no UI freeze

The first cut created the group with a blocking RunCallbacks + sleep loop inside SendInvite, freezing the window for ~5s. This commit replaces it with a small state machine (GroupTick) driven from the existing 200ms app timer: SendInvite just queues the invitee and starts group creation, and the invite fires once the group has settled. GroupTick is also called from the CLI oneshot loop so -i still works headless.

---

Testing

• Windows — validated live against the current Steam client. All five original RCM methods resolve correctly, and a call through a resolved index returns cleanly:

  RCM vtable: resolved 126 named methods
    BCreateRemotePlayInviteAndSession              -> index 113
    BIsStreamingSessionActive                      -> index 74
    SetStreamingDesktopToRemotePlayTogetherEnabled -> index 117
    ShowRemotePlayTogetherUI                       -> index 132
    CancelRemotePlayInviteAndSession               -> index 114 (anchored: Create@113, Join@115)
  

  Note BCreateRemotePlayInviteAndSession resolves to 113, not the header's 126 — this build has already drifted, which is exactly what the crash fix handles.
• Full control flow, live: invited two friends into a running game. Both joined, both showed up in the roster window and in the Shift-Tab player list, and I could grant/revoke keyboard, mouse and controller for each of them independently. Invite no longer freezes the UI.
• Linux / Steam Deck: the Linux branch compiles and the same name strings exist in steamclient.so, but I don't have a Deck to verify end-to-end. A Linux test from you or the community would be appreciated before merge.

Happy to split the commits into separate PRs, or adjust naming / style / UI to match your preferences.

[Raiden-Pax]

I compiled and tested it on linux and it crashed my steam every time. I think it might be bugged there, but I'd be willing to help debug it with you

[okabeeer]

I compiled and tested it on linux and it crashed my steam every time. I think it might be bugged there, but I'd be willing to help debug it with you

could you give me your discord so we can stay in touch? @Raiden-Pax

[okabeeer]

@Raiden-Pax
Greatly appreciate you testing on Linux and volunteering to debug; that’s exactly what this PR needed.
I'm almost certain I've found the problem, and it's specific to Linux. The by-name resolver reads the names of each method by scanning through the Steam client module’s memory, and it previously assumed the module was a contiguous chunk. That works for a PE image on Windows (a single committed mapping), but for a .so file on Linux it’s multiple PT_LOAD segments (text, rodata, data) separated by unmapped space. Therefore, a scan could end up jumping past a segment’s boundary into unmapped territory and segfault, crashing Steam at startup, which is why it didn’t happen on Windows.
I’ve pushed a fix to make sure all reads stay within mapped memory ranges and added opt-in logging. The branch is here: https://github.com/okabeeer/RemotePlayWhatever/tree/linux-vtable-fix

Could you build that and try this:

RPW_VTDEBUG=1 ./remoteplaywhatever 2> rpw-vt.log

and paste rpw-vt.log? If that crashes as well, a backtrace would show us exactly where:
gdb -batch -ex run -ex bt --args ./remoteplaywhatever
Two quick things that'll be helpful either way: (1) does the crash happen immediately at launch or only after you invite a friend? (2) What distribution are you running and which Steam client (native vs Flatpak)?
Thanks – if this solves the issue, I’ll merge it into the PR immediately.

[FerLuisxd]

Any updates on this? 👀

[NightCorpse]

@Raiden-Pax Greatly appreciate you testing on Linux and volunteering to debug; that’s exactly what this PR needed. I'm almost certain I've found the problem, and it's specific to Linux. The by-name resolver reads the names of each method by scanning through the Steam client module’s memory, and it previously assumed the module was a contiguous chunk. That works for a PE image on Windows (a single committed mapping), but for a .so file on Linux it’s multiple PT_LOAD segments (text, rodata, data) separated by unmapped space. Therefore, a scan could end up jumping past a segment’s boundary into unmapped territory and segfault, crashing Steam at startup, which is why it didn’t happen on Windows. I’ve pushed a fix to make sure all reads stay within mapped memory ranges and added opt-in logging. The branch is here: https://github.com/okabeeer/RemotePlayWhatever/tree/linux-vtable-fix

Could you build that and try this:

RPW_VTDEBUG=1 ./remoteplaywhatever 2> rpw-vt.log

and paste rpw-vt.log? If that crashes as well, a backtrace would show us exactly where: gdb -batch -ex run -ex bt --args ./remoteplaywhatever Two quick things that'll be helpful either way: (1) does the crash happen immediately at launch or only after you invite a friend? (2) What distribution are you running and which Steam client (native vs Flatpak)? Thanks – if this solves the issue, I’ll merge it into the PR immediately.

I tested the linux-vtable-fix branch on Arch Linux and managed to fix the initialization crash!

The issue was that the NameOf function wasn't scanning far enough into the Linux steamclient.so methods to find the telemetry strings (they are pushed further down the function body on Linux).

I simply increased the scan limit in ClientVTableByName.h around line 192:
for (int k = 0; k < 300; ++k)

With 300, it successfully resolves all methods. The UI and controls are working correctly!

The only issue I encountered was the lack of audio on the remote player's end.

rpw-vt.log output

[vt] module /home/user/.steam/sdk64//steamclient.so base=0x7f2b01200000 : 4 PT_LOAD segment(s)
[vt]   seg[0] 0x7f2b01200000 .. 0x7f2b01f8cef0
[vt]   seg[1] 0x7f2b01f8def0 .. 0x7f2b03cb011f
[vt]   seg[2] 0x7f2b03cb1140 .. 0x7f2b03e14000
[vt]   seg[3] 0x7f2b03e14be8 .. 0x7f2b03f02758
[vt] resolved 139 named method(s)
[vt] --- 139 resolved methods ---
[vt]   NotifySettingsChanged                            -> 139
[vt]   MarkTaskComplete                                 -> 138
[vt]   BGetRemotePlayTogetherMouseCursor                -> 135
[vt]   OnSendRemotePlayTogetherInvite                   -> 133
[vt]   OnRemotePlayUIMovedController                    -> 132
[vt]   DisbandRemotePlayTogetherGroup                   -> 131
[vt]   UpdateRemotePlayTogetherGroups                   -> 129
[vt]   EnableWifiRadioSoftwareState                     -> 58
[vt]   BRemoteClientConnectedToWifiAP                   -> 48
[vt]   SendSuspendLanPeerContent                        -> 26
[vt]   UnpairLocalWifiAP                                -> 56
[vt]   GetConnectedWifiAPClientID                       -> 49
[vt]   BRemoteClientHasStreamingSupported               -> 44
[vt]   CancelRemoteClientPairing                        -> 104
[vt]   GetRemoteDeviceCount                             -> 59
[vt]   BGetStreamingClientConfig                        -> 92
[vt]   GetRemoteClientConnectState                      -> 42
[vt]   StopRemoteClientStream                           -> 137
[vt]   GetStreamingPINSize                              -> 103
[vt]   GetRemoteClientStreamingEnabledCount             -> 35
[vt]   BIsStreamingSessionActiveForGame                 -> 77
[vt]   GetRemoteClientNameByIndex                       -> 33
[vt]   Shutdown                                         -> 140
[vt]   BRemoteClientHasLocalConnection                  -> 43
[vt]   OnRemoteClientRemotePlayClearControllers         -> 127
[vt]   BRemoteClientHasStreamingSupportedByIndex        -> 30
[vt]   SetRemotePlayTogetherBitrateOverride             -> 109
[vt]   BHasRemotePlayInviteAndSession                   -> 110
[vt]   GetStreamingSessionForRemotePlayer               -> 120
[vt]   BRemoteClientStreaming                           -> 37
[vt]   SendStreamTransportSignal                        -> 12
[vt]   ShowRemotePlayTogetherUI                         -> 134
[vt]   GetClientPlatformTypes                           -> 16
[vt]   BIsStreamClientRunningConnectedToClient          -> 89
[vt]   BGetStreamTransportSignal                        -> 11
[vt]   UsedVideoH264                                    -> 106
[vt]   GetStreamClientPlayer                            -> 7
[vt]   GetPerUserInputSettings                          -> 124
[vt]   ProcessStreamShutdown                            -> 4
[vt]   BQueueControllerConfigMessageForRemote           -> 94
[vt]   UpdateStreamClientResolution                     -> 5
[vt]   GetWifiAPStateJSONString                         -> 51
[vt]   ProcessStreamAvailable                           -> 3
[vt]   BAnyRemoteClientCanSteamVR                       -> 41
[vt]   SetStreamingDesktopToRemotePlayTogetherEnabled   -> 119
[vt]   GetRemoteClientConnectedCount                    -> 34
[vt]   GetRemoteClientAppStateByIndex                   -> 32
[vt]   ConnectToRemoteAddress                           -> 14
[vt]   ConnectToRemote                                  -> 13
[vt]   JoinRemotePlaySession                            -> 117
[vt]   PairViaWifiAP                                    -> 55
[vt]   GetRemotePlayTogetherGroupIDForOverlayPID        -> 113
[vt]   SendEnableAllDownloadsToRemoteClient             -> 28
[vt]   GetRemoteClientStreamingSession                  -> 38
[vt]   StreamingAudioFinished                           -> 2
[vt]   BRemoteClientIsConnected                         -> 22
[vt]   BCanPairViaWifiAP                                -> 52
[vt]   GetActiveVRStreamingInvitationClientID           -> 50
[vt]   BStreamingClientWantsRecentGames                 -> 79
[vt]   UpdateStreamClientNetworkUtilization             -> 9
[vt]   GetStreamClientFormFactor                        -> 8
[vt]   GetRemoteClientFormFactor                        -> 39
[vt]   LaunchAppResult                                  -> 82
[vt]   GetRemoteClientConnectStateByIndex               -> 23
[vt]   BIsStreamingEnabled                              -> 71
[vt]   BRemoteClientWifiAPUnpaired                      -> 54
[vt]   RefreshRemoteClients                             -> 15
[vt]   GetWifiDongleProblemFlags                        -> 57
[vt]   SetUIReadyForStream                              -> 0
[vt]   GetRemoteClientCount                             -> 17
[vt]   SendDownloadIndexChangeToRemoteClient            -> 25
[vt]   GetRemoteDeviceStreamingSession                  -> 64
[vt]   BGetControllerConfigMessageForLocal              -> 95
[vt]   GetRemoteClientIDByIndex                         -> 18
[vt]   BRemoteClientHasStreamingEnabled                 -> 45
[vt]   GetConnectedRemoteClientIDByIndex                -> 19
[vt]   BRemoteClientDownloadManagementEnabled           -> 20
[vt]   BHasConnectedClients                             -> 21
[vt]   SendDownloadQueueChangeToRemoteClient            -> 24
[vt]   UnpairRemoteDevice                               -> 67
[vt]   GetCloudGameTimeRemaining                        -> 136
[vt]   CancelRemotePlayInviteAndSession                 -> 116
[vt]   SetPerUserControllerInputEnabled                 -> 123
[vt]   GetRemoteClientName                              -> 36
[vt]   ProcessStreamClientDisconnected                  -> 10
[vt]   SendRemoveFromDownloadsToRemoteClient            -> 29
[vt]   GetRemoteDeviceIDByIndex                         -> 60
[vt]   GetRemoteDeviceNameByIndex                       -> 61
[vt]   AcceptAllEULAs                                   -> 86
[vt]   SetPerUserMouseInputEnabled                      -> 122
[vt]   BRemoteDeviceStreaming                           -> 63
[vt]   GetRemoteDeviceFormFactor                        -> 65
[vt]   SetRemoteDeviceSpectateAllowed                   -> 100
[vt]   UnpairRemoteClient                               -> 66
[vt]   UnpairRemoteDevices                              -> 68
[vt]   BIsStreamingSupported                            -> 69
[vt]   BIsStreamingDisabledBySystemPolicy               -> 70
[vt]   GetControllerConfig                              -> 98
[vt]   SetStreamingEnabled                              -> 72
[vt]   StreamingAudioPreparationComplete                -> 1
[vt]   StartStream                                      -> 73
[vt]   GetRemoteDeviceName                              -> 62
[vt]   BIsRemoteLaunch                                  -> 74
[vt]   BIsBigPictureActiveForStreaming                  -> 75
[vt]   GetRemoteClientAppState                          -> 46
[vt]   StopStreamingSession                             -> 80
[vt]   BIsStreamStartInProgress                         -> 83
[vt]   LaunchAppResultRequestLaunchOption               -> 84
[vt]   BRemoteClientIsLowSpecHardware                   -> 47
[vt]   AcceptEULA                                       -> 85
[vt]   BRemoteClientCanStreamSteamVR                    -> 40
[vt]   BIsStreamingClientConnected                      -> 78
[vt]   GetRemoteClientPlatformName                      -> 87
[vt]   LaunchAppProgress                                -> 81
[vt]   BIsStreamClientRunning                           -> 88
[vt]   BIsStreamClientRemotePlayTogether                -> 90
[vt]   GetStreamClientRemoteSteamVersion                -> 91
[vt]   RequestControllerConfig                          -> 96
[vt]   PostControllerConfig                             -> 97
[vt]   BRemoteClientHasStreamingEnabledByIndex          -> 31
[vt]   SetRemoteDeviceAuthorized                        -> 99
[vt]   BStreamingDesktopToRemotePlayTogetherEnabled     -> 118
[vt]   SetStreamingDriversInstalled                     -> 101
[vt]   SetStreamingPIN                                  -> 102
[vt]   BIsStreamingSessionActive                        -> 76
[vt]   UsedVideoX264                                    -> 105
[vt]   UsedVideoHEVC                                    -> 107
[vt]   SetRemotePlayTogetherQualityOverride             -> 108
[vt]   BCreateRemotePlayGroup                           -> 111
[vt]   GetLocalRemotePlayTogetherGroupID                -> 112
[vt]   UpdateRemotePlayTogetherGroup                    -> 130
[vt]   GetAvailableRemotePlayTogetherGuestID            -> 114
[vt]   BCreateRemotePlayInviteAndSession                -> 115
[vt]   BRemoteClientCanPairViaWifiAP                    -> 53
[vt]   SendSuspendDownloadThrottleingToRemoteClient     -> 27
[vt]   BSetStreamingClientConfig                        -> 93
[vt]   SetPerUserKeyboardInputEnabled                   -> 121
[vt]   OnClientUsedInput                                -> 125
[vt]   OnPlaceholderStateChanged                        -> 126

(remoteplaywhatever:327386): Gtk-WARNING **: 17:29:06.992: cache version is different 1 != 2