My backend on 401 sets the `www-authenticate` head...

# ktor

[ursus]

My backend on 401 sets the www-authenticate header this way OAuth2 realm="WSO2 API Manager", error="invalid_token", error_description="The access token expired"

-- It doesn't contain the Bearer scheme, therefore refreshTokens in ktor client doesnt work

Any way to workaround this? Changing the backend is unfortunatelly not an option

[ursus]

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[Aleksei Tirman [JB]]

You can define a new authentication provider class by implementing the AuthProvider interface and delegating to BearerAuthProvider except for the isApplicable method:

class MyProvider(private val delegate: BearerAuthProvider, private val realm: String?): AuthProvider {
    @Deprecated("Please use sendWithoutRequest function instead")
    override val sendWithoutRequest: Boolean
        get() = delegate.sendWithoutRequest

    override fun sendWithoutRequest(request: HttpRequestBuilder): Boolean {
        return delegate.sendWithoutRequest(request)
    }

    override suspend fun addRequestHeaders(request: HttpRequestBuilder, authHeader: HttpAuthHeader?) {
        delegate.addRequestHeaders(request, authHeader)
    }

    override fun isApplicable(auth: HttpAuthHeader): Boolean {
        if (auth.authScheme !in listOf("Bearer", "OAuth2")) {
            return false
        }
        val isSameRealm = when {
            realm == null -> true
            auth !is HttpAuthHeader.Parameterized -> false
            else -> auth.parameter("realm") == realm
        }
        return isSameRealm
    }
}

The actual configuration of the provider could look like this:

val client = HttpClient(CIO) {
    install(Auth) {
        val realm = ""
        providers.add(MyProvider(
            BearerAuthProvider(
                refreshTokens = { BearerTokens("", "") },
                loadTokens = { BearerTokens("", "") },
                sendWithoutRequestCallback = { true },
                realm = realm
            ),
            realm
        ))
    }
}