Relocate AuthTokenGenerator to aws-signing-common

Author: lauzadis

runtime/auth/aws-signing-common/common/src/aws/smithy/kotlin/runtime/auth/awssigning/AuthTokenGenerator.kt

@@ -0,0 +1,63 @@
+/*
+* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+* SPDX-License-Identifier: Apache-2.0
+*/
+package aws.smithy.kotlin.runtime.auth.awssigning
+
+import aws.smithy.kotlin.runtime.auth.awscredentials.Credentials
+import aws.smithy.kotlin.runtime.auth.awscredentials.CredentialsProvider
+import aws.smithy.kotlin.runtime.auth.awssigning.AwsSigningConfig.Companion.invoke
+import aws.smithy.kotlin.runtime.http.HttpMethod
+import aws.smithy.kotlin.runtime.http.request.HttpRequest
+import aws.smithy.kotlin.runtime.net.url.Url
+import aws.smithy.kotlin.runtime.time.Clock
+import aws.smithy.kotlin.runtime.util.ExpiringValue
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.minutes
+import kotlin.time.Duration.Companion.seconds
+
+// The default expiration value to use for [Credentials] when none is provided.
+private val DEFAULT_CREDENTIALS_EXPIRATION = 10.minutes
+
+/**
+ * Generates an authentication token, which is a SigV4-signed URL with the HTTP scheme removed.
+ * @param service The name of the service the token is being generated for
+ * @param credentialsProvider The [CredentialsProvider] which will provide credentials to use when generating the auth token
+ * @param credentialsRefreshBuffer The amount of time before the resolved [Credentials] expire in which they are considered expired, defaults to 10 seconds.
+ * @param signer The [AwsSigner] implementation to use when creating the authentication token
+ * @param clock The [Clock] implementation to use
+ */
+public class AuthTokenGenerator(
+    public val service: String,
+    public val credentialsProvider: CredentialsProvider,
+    public val credentialsRefreshBuffer: Duration = 10.seconds,
+    public val signer: AwsSigner,
+    public val clock: Clock = Clock.System,
+) {
+    private lateinit var credentials: ExpiringValue<Credentials>
+
+    private fun Url.trimScheme(): String = toString().removePrefix(scheme.protocolName).removePrefix("://")
+
+    public suspend fun generateAuthToken(endpoint: Url, region: String, expiration: Duration): String {
+        if (!::credentials.isInitialized || (credentials.expiresAt - clock.now()).absoluteValue <= credentialsRefreshBuffer) {
+            val resolved = credentialsProvider.resolve()
+            credentials = ExpiringValue(resolved, resolved.expiration ?: (clock.now() + DEFAULT_CREDENTIALS_EXPIRATION))
+        }
+
+        val req = HttpRequest(HttpMethod.GET, endpoint)
+
+        val creds = credentials.value
+        val serv = service
+
+        val config = AwsSigningConfig {
+            credentials = creds
+            this.region = region
+            service = serv
+            signingDate = clock.now()
+            expiresAfter = expiration
+            signatureType = AwsSignatureType.HTTP_REQUEST_VIA_QUERY_PARAMS
+        }
+
+        return signer.sign(req, config).output.url.trimScheme()
+    }
+}