How to authenticate a gRPC call for the Assistant SDK?

Question

I'm using the Swift gRPC library (which curiously isn't listed on gRPC's website, but there is a GitHub repo for it) to build an implementation of the Google Assistant SDK for macOS. I've gotten my OAuth2 credentials and token, and am trying to make the initial request to begin a conversation, however it fails to do so.

I always get the error Google_Assistant_Embedded_V1Alpha1_EmbeddedAssistantClientError error 1.) and gRPC.CallError error 1.

I ran Wireshark to try and debug the issue, and I saw the my computer is attempting to establish a connection but eventually ends up aborting the connection. I think it may be due to a TLS issue, but I'm not sure if that actually is the case or how to fix it.

I noticed the service initialization function has an overload where you specify certificates, but I don't know what to put there (or if that function needs to be used at all)

typealias AssistantService = Google_Assistant_Embedded_V1Alpha1_EmbeddedAssistantService
typealias AssistantCall = Google_Assistant_Embedded_V1Alpha1_EmbeddedAssistantConverseCall
typealias AudioInConfig = Google_Assistant_Embedded_V1alpha1_AudioInConfig
typealias AudioOutConfig = Google_Assistant_Embedded_V1alpha1_AudioOutConfig
typealias ConverseRequest = Google_Assistant_Embedded_V1alpha1_ConverseRequest
typealias ConverseConfig = Google_Assistant_Embedded_V1alpha1_ConverseConfig    

var service: AssistantService?
var currentCall: AssistantCall?

public init() {
    service = AssistantService(address: Constants.ASSISTANT_API_ENDPOINT)
    let token = "Bearer \(UserDefaults.standard.string(forKey: Constants.AUTH_TOKEN_KEY)!)"
    service?.metadata = Metadata(["authorization" : token])
}

func initiateRequest() {
    var request =   ConverseRequest()
    request.config = ConverseConfig()

    var audioInConfig = AudioInConfig()
    audioInConfig.sampleRateHertz = 16000
    audioInConfig.encoding = .linear16
    request.config.audioInConfig = audioInConfig


    var audioOutConfig = AudioOutConfig()
    audioOutConfig.sampleRateHertz = 16000
    audioOutConfig.encoding = .linear16
    audioOutConfig.volumePercentage = 50
    request.config.audioOutConfig = audioOutConfig

    do {
        currentCall = try service?.converse(completion: { result in
            print("Result code \(result.statusCode)")
            print("Result description \(result.description)")
            print("Metadata \(String(describing: result.initialMetadata))")
            print("Status message \(result.statusMessage ?? "Error")")
            print("Obj description \(String(describing: result))")
            print("result \(result)")
        })

        try currentCall?.send(request) { err in
            print("Error in initial request: \(err)")
        }
    } catch {
        print("Initial error \(error)")
    }
}

This is what the Wireshark for it looks like, if it is any help:

Answer 1

I had to add the roots.pem file found here to my project and use it as follows:

let u = Bundle.main.url(forResource: "roots", withExtension: "pem")!
let certificate = try! String(contentsOf: u)
let token = "Bearer \(UserDefaults.standard.string(forKey: Constants.AUTH_TOKEN_KEY)!)"
service = AssistantService(address: Constants.ASSISTANT_API_ENDPOINT, certificates: certificate, host: nil)
service?.metadata = Metadata(["authorization" : token])