fix: usage of pre-calculated checksum values (#852)

Author: lauzadis

.changes/47b592af-ba43-43ad-b38b-534845549cfd.json

@@ -0,0 +1,5 @@
+{
+    "id": "47b592af-ba43-43ad-b38b-534845549cfd",
+    "type": "bugfix",
+    "description": "Fix usage of precalculated checksum values"
+}

runtime/protocol/http-client/api/http-client.api

@@ -136,6 +136,10 @@ public final class aws/smithy/kotlin/runtime/http/engine/TlsContext$Companion {
 public final class aws/smithy/kotlin/runtime/http/engine/internal/ManagedHttpClientEngineKt {
 }
 
+public final class aws/smithy/kotlin/runtime/http/interceptors/ChecksumMismatchException : aws/smithy/kotlin/runtime/ClientException {
+	public fun <init> (Ljava/lang/String;)V
+}
+
 public final class aws/smithy/kotlin/runtime/http/interceptors/FlexibleChecksumsResponseInterceptor$Companion {
 	public final fun getChecksumHeaderValidated ()Laws/smithy/kotlin/runtime/util/AttributeKey;
 }

runtime/protocol/http-client/common/src/aws/smithy/kotlin/runtime/http/interceptors/FlexibleChecksumsRequestInterceptor.kt

@@ -42,7 +42,6 @@ public class FlexibleChecksumsRequestInterceptor<I>(
         checksumAlgorithmName = checksumAlgorithmNameInitializer(input)
     }
 
-    @OptIn(ExperimentalCoroutinesApi::class)
     override suspend fun modifyBeforeRetryLoop(context: ProtocolRequestInterceptorContext<Any, HttpRequest>): HttpRequest {
         val logger = coroutineContext.getLogger<FlexibleChecksumsRequestInterceptor<I>>()
 
@@ -57,7 +56,7 @@ public class FlexibleChecksumsRequestInterceptor<I>(
             "Can't calculate the checksum of an empty body"
         }
 
-        val headerName = "x-amz-checksum-$checksumAlgorithmName"
+        val headerName = "x-amz-checksum-$checksumAlgorithmName".lowercase()
         logger.debug { "Resolved checksum header name: $headerName" }
 
         // remove all checksum headers except for $headerName
@@ -140,7 +139,7 @@ public class FlexibleChecksumsRequestInterceptor<I>(
      * Convert an [HttpBody] with an underlying [HashingSource] or [HashingByteReadChannel]
      * to a [CompletingSource] or [CompletingByteReadChannel], respectively.
      */
-    internal fun HttpBody.toCompletingBody(deferred: CompletableDeferred<String>) = when (this) {
+    private fun HttpBody.toCompletingBody(deferred: CompletableDeferred<String>) = when (this) {
         is HttpBody.SourceContent -> CompletingSource(deferred, (readFrom() as HashingSource)).toHttpBody(contentLength)
         is HttpBody.ChannelContent -> CompletingByteReadChannel(deferred, (readFrom() as HashingByteReadChannel)).toHttpBody(contentLength)
         else -> throw ClientException("HttpBody type is not supported")

runtime/protocol/http-client/common/src/aws/smithy/kotlin/runtime/http/interceptors/FlexibleChecksumsResponseInterceptor.kt

@@ -83,7 +83,7 @@ public class FlexibleChecksumsResponseInterceptor<I>(
     }
 }
 
-internal class ChecksumMismatchException(message: String?) : ClientException(message)
+public class ChecksumMismatchException(message: String?) : ClientException(message)
 
 /**
  * An [SdkSource] which validates the underlying [hashingSource]'s checksum against an [expectedChecksum].

runtime/protocol/http-client/common/test/aws/smithy/kotlin/runtime/http/interceptors/FlexibleChecksumsRequestInterceptorTest.kt

@@ -181,6 +181,30 @@ class FlexibleChecksumsRequestInterceptorTest {
         assertEquals(expectedHash.digest().encodeBase64String(), completableDeferred.getCompleted())
     }
 
+    @Test
+    fun itUsesPrecalculatedChecksum() = runTest {
+        val req = HttpRequestBuilder().apply {
+            body = ByteArrayContent("<Foo>bar</Foo>".encodeToByteArray())
+        }
+        val checksumAlgorithmName = "sha256"
+        val precalculatedChecksumValue = "sha256-checksum-value"
+        req.headers { append("x-amz-checksum-$checksumAlgorithmName", precalculatedChecksumValue) }
+
+        val op = newTestOperation<Unit, Unit>(req, Unit)
+
+        op.interceptors.add(
+            FlexibleChecksumsRequestInterceptor<Unit> {
+                checksumAlgorithmName
+            },
+        )
+
+        op.roundTrip(client, Unit)
+        val call = op.context.attributes[HttpOperationContext.HttpCallList].first()
+
+        assertEquals(1, call.request.headers.getNumChecksumHeaders())
+        assertEquals(precalculatedChecksumValue, call.request.headers["x-amz-checksum-sha256"])
+    }
+
     private fun Headers.getNumChecksumHeaders(): Long = entries().stream()
         .filter { (name, _) -> name.startsWith("x-amz-checksum-") }
         .count()