Expose Connection environment variables to the app start

[TheElixZammuto]

Description

When starting apps, some environment variables releated to the connection are passed to the commands (pre/detatched/do)
Instead of #1096 that relies on text replacement, this uses the environment variables system, which should be more robust and secure (Although I haven't tested cmd injection techinques). I've also documented inside the Web UI which vars are exposed and how to consume them in a standard cmd command on Windows (other platform suggestions are welcome!)

This should make scripts more elegant instead of relying on parsing log files.

Screenshot

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Dependency update (updates to dependencies)
• Documentation update (changes to documentation)
• Repository update (changes to repository files, e.g. .github/...)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the in code docstring/documentation-blocks for new or existing methods/components

Branch Updates

LizardByte requires that branches be up-to-date before merging. This means that after any PR is merged, this branch
must be updated before it can be merged. You must also
Allow edits from maintainers.

• I want maintainers to keep my branch updated

[ReenigneArcher]

Should we add something to the docs about environment variables as well?

We could also update these do command examples to use the environment variables: https://github.com/LizardByte/Sunshine/blob/nightly/docs/source/about/app_examples.rst?plain=1#L131-L183

Linux Example: https://docs.lizardbyte.dev/projects/sunshine/en/nightly/about/app_examples.html#changing-resolution-and-refresh-rate-linux-x11

macOS Example: https://docs.lizardbyte.dev/projects/sunshine/en/nightly/about/app_examples.html#changing-resolution-and-refresh-rate-macos

And we could remove this section (don't think it will be useful after this is merged): https://github.com/LizardByte/Sunshine/blob/nightly/docs/source/about/app_examples.rst?plain=1#L188-L189

[Nonary]

Ideally all parameters of the client should be accessible, anyone opposed to something like that? I’m guessing it would be documentation and more code changes?

[Nonary]

Specifically there is a bunch of moonlight variables logged when the log level as set to debug, which gives a lot of useful information. I’ve been wanting to make those accessible but it appears those are logged after the stream starts, not beforehand.

[TheElixZammuto]

Specifically there is a bunch of moonlight variables logged when the log level as set to debug, which gives a lot of useful information. I’ve been wanting to make those accessible but it appears those are logged after the stream starts, not beforehand.

Yup, the app starts when a /launch command is issued on the client side, so we can only access the variables sent using this endpoint. Do you have any specific variable you want to be passed?

[Nonary]

Specifically there is a bunch of moonlight variables logged when the log level as set to debug, which gives a lot of useful information. I’ve been wanting to make those accessible but it appears those are logged after the stream starts, not beforehand.

Yup, the app starts when a /launch command is issued on the client side, so we can only access the variables sent using this endpoint. Do you have any specific variable you want to be passed?

All of the parameters logged that start with a=nv-video would be great

a=x-nv-video[0].clientViewportWd:3840 
a=x-nv-video[0].clientViewportHt:2160 
a=x-nv-video[0].maxFPS:60 
a=x-nv-video[0].packetSize:1392 
a=x-nv-video[0].rateControlMode:4 
a=x-nv-video[0].timeoutLengthMs:7000 
a=x-nv-video[0].framesWithInvalidRefThreshold:0 
a=x-nv-video[0].initialBitrateKbps:80000 
a=x-nv-video[0].initialPeakBitrateKbps:80000 
a=x-nv-vqos[0].bw.minimumBitrateKbps:80000 
a=x-nv-vqos[0].bw.maximumBitrateKbps:80000 
a=x-nv-vqos[0].fec.enable:1 
a=x-nv-vqos[0].videoQualityScoreUpdateTime:5000 
a=x-nv-vqos[0].qosTrafficType:5 
a=x-nv-aqos.qosTrafficType:4 
a=x-nv-general.featureFlags:167 
a=x-nv-general.useReliableUdp:13 
a=x-nv-vqos[0].fec.minRequiredFecPackets:2 
a=x-nv-vqos[0].bllFec.enable:0 
a=x-nv-vqos[0].drc.enable:0 
a=x-nv-general.enableRecoveryMode:0 
a=x-nv-video[0].videoEncoderSlicesPerFrame:1 
a=x-nv-clientSupportHevc:1 
a=x-nv-vqos[0].bitStreamFormat:1 
a=x-nv-video[0].dynamicRangeMode:1 
a=x-nv-video[0].maxNumReferenceFrames:1 
a=x-nv-video[0].clientRefreshRateX100:0 
a=x-nv-audio.surround.numChannels:2 
a=x-nv-audio.surround.channelMask:3 
a=x-nv-audio.surround.enable:0 
a=x-nv-audio.surround.AudioQuality:0 
a=x-nv-aqos.packetDuration:5 
a=x-nv-video[0].encoderCscMode:0 

But I suppose just having HDR, fps and resolution is fine for my use cases though.

What's the option for figuring out if user has enabled/disabled the feature to close games on stream end? I could use that for my playnite watcher script.

[TheElixZammuto]

Specifically there is a bunch of moonlight variables logged when the log level as set to debug, which gives a lot of useful information. I’ve been wanting to make those accessible but it appears those are logged after the stream starts, not beforehand.

Yup, the app starts when a /launch command is issued on the client side, so we can only access the variables sent using this endpoint. Do you have any specific variable you want to be passed?

All of the parameters logged that start with a=nv-video would be great

a=x-nv-video[0].clientViewportWd:3840 
...

But I suppose just having HDR, fps and resolution is fine for my use cases though.

Unfortunately these are passed on the RTSP stage, so they cannot be passed on the app start

What's the option for figuring out if user has enabled/disabled the feature to close games on stream end? I could use that for my playnite watcher script.

It seems that it's a client-only option

EDIT: I think the best thing is to make in a future PR a named-pipe to handle all of these cases, so the integration can be completed

[ReenigneArcher]

Can we add a macOS example?

Also, how about adding a section about the env variables to the docs? I could take care of this in a separate PR in order to get this moving along.

[ReenigneArcher]

@TheElixZammuto

Can we set a default value to empty/null if the client doesn't provide it? I'm thinking something similar to Python's os.getenv method. os.getenv(key, "some default value")

Apparently, Moonlight on Apple doesn't provide UUID (and who knows about every possible homebrew moonlight client). https://discord.com/channels/804382334370578482/1074377411069747250/1135639228613664858

[Xythus]

Perhaps something like

  std::string
  get_arg(const args_t &args, const char *name, const char *default_value = nullptr) {
    auto it = args.find(name);
    if (it == std::end(args)) {
      if (default_value != NULL) {
        return std::string(default_value);
      }
      
      throw std::out_of_range(name);
    }
    return it->second;
  }

Used as such:

   launch_session.gcm_key = util::from_hex<crypto::aes_t>(get_arg(args, "rikey", "0"), true);
    std::stringstream mode = std::stringstream(get_arg(args, "mode", "0x0x0"));
    // Split mode by the char "x", to populate width/height/fps
    int x = 0;
    std::string segment;
    while (std::getline(mode, segment, 'x')) {
      if (x == 0) launch_session.width = atoi(segment.c_str());
      if (x == 1) launch_session.height = atoi(segment.c_str());
      if (x == 2) launch_session.fps = atoi(segment.c_str());
      x++;
    }
    
    launch_session.unique_id = (get_arg(args, "uniqueid", "0123456789ABCDEF"));
    launch_session.uuid = (get_arg(args, "uuid", "00000000000000000000000000000000"));
    launch_session.appid = util::from_view(get_arg(args, "appid", "0123456789"));
    launch_session.enable_sops = util::from_view(get_arg(args, "sops", "0"));
    launch_session.surround_info = util::from_view(get_arg(args, "surroundAudioInfo", "0"));
    launch_session.gcmap = util::from_view(get_arg(args, "gcmap", "0"));
    launch_session.enable_hdr = 0;
    if (args.find("enableHdr"s) != std::end(args)) {
      launch_session.enable_hdr = util::from_view(get_arg(args, "enableHdr", "0"));
    }
    uint32_t prepend_iv = util::endian::big<uint32_t>(util::from_view(get_arg(args, "rikeyid", "0")));