How to use firebase admin with ktor 2.0 - firebase-authentication

Question

Does anyone have an idea how to convert these codes to ktor 2.0.
https://gist.github.com/togisoft/d1113a83eeb1d6b52031f77fe780ce48

Answer 1

If someone needs to see a complete sample of Aleksei's answer, I created a sample repository.
I did make some slight tweaks to the other answer as the implementation error was missing the correct messaging from the original gist.
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.FirebaseToken
import io.ktor.http.auth.*
import io.ktor.server.application.*
import io.ktor.server.auth.*
import io.ktor.server.request.*
import io.ktor.server.response.*
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.withContext
class FirebaseAuthProvider(config: FirebaseConfig): AuthenticationProvider(config) {
val authHeader: (ApplicationCall) -> HttpAuthHeader? = config.authHeader
private val authFunction = config.firebaseAuthenticationFunction
override suspend fun onAuthenticate(context: AuthenticationContext) {
val token = authHeader(context.call)
if (token == null) {
context.challenge(FirebaseJWTAuthKey, AuthenticationFailedCause.InvalidCredentials) { challengeFunc, call ->
challengeFunc.complete()
call.respond(UnauthorizedResponse(HttpAuthHeader.bearerAuthChallenge(realm = FIREBASE_AUTH)))
}
return
}
try {
val principal = verifyFirebaseIdToken(context.call, token, authFunction)
if (principal != null) {
context.principal(principal)
}
} catch (cause: Throwable) {
val message = cause.message ?: cause.javaClass.simpleName
context.error(FirebaseJWTAuthKey, AuthenticationFailedCause.Error(message))
}
}
}
class FirebaseConfig(name: String?) : AuthenticationProvider.Config(name) {
internal var authHeader: (ApplicationCall) -> HttpAuthHeader? =
{ call -> call.request.parseAuthorizationHeaderOrNull() }
var firebaseAuthenticationFunction: AuthenticationFunction<FirebaseToken> = {
throw NotImplementedError(FirebaseImplementationError)
}
fun validate(validate: suspend ApplicationCall.(FirebaseToken) -> User?) {
firebaseAuthenticationFunction = validate
}
}
public fun AuthenticationConfig.firebase(name: String? = FIREBASE_AUTH, configure: FirebaseConfig.() -> Unit) {
val provider = FirebaseAuthProvider(FirebaseConfig(name).apply(configure))
register(provider)
}
suspend fun verifyFirebaseIdToken(
call: ApplicationCall,
authHeader: HttpAuthHeader,
tokenData: suspend ApplicationCall.(FirebaseToken) -> Principal?
): Principal? {
val token: FirebaseToken = try {
if (authHeader.authScheme == "Bearer" && authHeader is HttpAuthHeader.Single) {
withContext(Dispatchers.IO) {
FirebaseAuth.getInstance().verifyIdToken(authHeader.blob)
}
} else {
null
}
} catch (ex: Exception) {
ex.printStackTrace()
return null
} ?: return null
return tokenData(call, token)
}
private fun HttpAuthHeader.Companion.bearerAuthChallenge(realm: String): HttpAuthHeader {
return HttpAuthHeader.Parameterized("Bearer", mapOf(HttpAuthHeader.Parameters.Realm to realm))
}
private fun ApplicationRequest.parseAuthorizationHeaderOrNull() = try {
parseAuthorizationHeader()
} catch (ex: IllegalArgumentException) {
println("failed to parse token")
null
}
const val FIREBASE_AUTH = "FIREBASE_AUTH"
private const val FirebaseJWTAuthKey: String = "FirebaseAuth"
private const val FirebaseImplementationError =
"Firebase auth validate function is not specified, use firebase { validate { ... } }to fix"
Then to actually use in your project created an extension function on Application. Be sure that the Firebase Admin SDK has been initialized with credentials before installing the Firebase authentication plugin on Ktor.
fun Application.configureFirebaseAuth() {
FirebaseAdmin.init()
install(Authentication) {
firebase {
validate {
// TODO look up user profile to fill in any additional information on top of firebase user profile
User(it.uid, it.name)
}
}
}
}
Finally wrap a route with the authentication function:
authenticate(FIREBASE_AUTH) {
get("/authenticated") {
val user: User = call.principal() ?: return#get call.respond(HttpStatusCode.Unauthorized)
call.respond("User is authenticated: $user")
}
}

Answer 2

The converted to Ktor 2.0.* code is the following:
import io.ktor.http.auth.*
import io.ktor.serialization.*
import io.ktor.server.application.*
import io.ktor.server.auth.*
import io.ktor.server.request.*
import io.ktor.server.response.*
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.withContext
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.FirebaseToken
class FirebaseAuthProvider(config: FirebaseConfig): AuthenticationProvider(config) {
val authHeader: (ApplicationCall) -> HttpAuthHeader? = config.authHeader
private val authFunction = config.firebaseAuthenticationFunction
override suspend fun onAuthenticate(context: AuthenticationContext) {
val token = authHeader(context.call)
if (token == null) {
context.challenge(FirebaseJWTAuthKey, AuthenticationFailedCause.InvalidCredentials) { challengeFunc, call ->
challengeFunc.complete()
call.respond(UnauthorizedResponse(HttpAuthHeader.bearerAuthChallenge(realm = "firebaseAuth")))
}
return
}
try {
val principal = verifyFirebaseIdToken(context.call, token, authFunction)
if (principal != null) {
context.principal(principal)
}
} catch (cause: Throwable) {
val message = cause.message ?: cause.javaClass.simpleName
context.error(FirebaseJWTAuthKey, AuthenticationFailedCause.Error(message))
}
}
}
class FirebaseConfig(name: String?) : AuthenticationProvider.Config(name) {
internal var authHeader: (ApplicationCall) -> HttpAuthHeader? =
{ call -> call.request.parseAuthorizationHeaderOrNull() }
var firebaseAuthenticationFunction: AuthenticationFunction<FirebaseToken> = {
throw NotImplementedError(FirebaseImplementationError)
}
fun validate(validate: suspend ApplicationCall.(FirebaseToken) -> User?) {
firebaseAuthenticationFunction = validate
}
}
public fun AuthenticationConfig.firebase(name: String? = "firebaseAuth", configure: FirebaseConfig.() -> Unit) {
val provider = FirebaseAuthProvider(FirebaseConfig(name).apply(configure))
register(provider)
}
suspend fun verifyFirebaseIdToken(
call: ApplicationCall,
authHeader: HttpAuthHeader,
tokenData: suspend ApplicationCall.(FirebaseToken) -> Principal?
): Principal? {
val token: FirebaseToken = try {
if (authHeader.authScheme == "Bearer" && authHeader is HttpAuthHeader.Single) {
withContext(Dispatchers.IO) {
FirebaseAuth.getInstance().verifyIdToken(authHeader.blob)
}
} else {
null
}
} catch (ex: Exception) {
ex.printStackTrace()
return null
} ?: return null
return tokenData(call, token)
}
private fun HttpAuthHeader.Companion.bearerAuthChallenge(realm: String): HttpAuthHeader {
return HttpAuthHeader.Parameterized("Bearer", mapOf(HttpAuthHeader.Parameters.Realm to realm))
}
private fun ApplicationRequest.parseAuthorizationHeaderOrNull() = try {
parseAuthorizationHeader()
} catch (ex: IllegalArgumentException) {
println("failed to parse token")
null
}
private const val FirebaseJWTAuthKey: String = "FirebaseAuth"
private const val FirebaseImplementationError =
"Firebase auth validate function is not specified, use firebase { { ... } }to fix"