com.zepben.evolve.streaming.grpc.TokenCallCredentials.kt Maven / Gradle / Ivy

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SDK for interaction with the evolve platform

There is a newer version: 0.24.0rc1

/*
 * Copyright 2022 Zeppelin Bend Pty Ltd
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

package com.zepben.evolve.streaming.grpc

import com.zepben.auth.common.AuthException
import io.grpc.CallCredentials
import io.grpc.Metadata
import io.grpc.Metadata.ASCII_STRING_MARSHALLER
import io.grpc.Status
import java.util.concurrent.Executor

internal val AUTHORIZATION_METADATA_KEY: Metadata.Key = Metadata.Key.of("Authorization", ASCII_STRING_MARSHALLER)

/**
 * Call credentials that sets the "Authorization" metadata header to a token string.
 * The token string is updated each call using a factory function specified upon instantiation.
 * In practice, this function will be a method of an object that manages token retrieval and returns a cached token if it isn't expired.
 */
class TokenCallCredentials(private val getToken: () -> String) : CallCredentials() {

    /**
     * Gets token using provided function [getToken] and assigns it to the "Authorization" header in a gRPC request.
     */
    override fun applyRequestMetadata(requestInfo: RequestInfo, executor: Executor, applier: MetadataApplier) {
        try {
            val headers = Metadata()
            headers.put(AUTHORIZATION_METADATA_KEY, getToken())
            applier.apply(headers)
        } catch (e: Exception) {
            when (e) {
                //UNAVAILABLE used here to match python sdk behaviour that we don't control
                is AuthException -> {
                    val grpcStatusCode = when (e.statusCode) {
                        401 -> Status.UNAVAILABLE //Unauthorized / wrong client ID
                        403 -> Status.UNAVAILABLE //invalid_grant / wrong email or password
                        429 -> Status.UNAVAILABLE //user blocked / too many requests
                        else -> Status.UNAUTHENTICATED
                    }
                    return applier.fail(
                        grpcStatusCode.withDescription("Getting authorization data from token fetcher failed with error: $e").withCause(e)
                    )
                }
                else -> applier.fail(Status.fromThrowable(e.cause ?: e))
            }

        }
    }

}