Temporary wiring for event signer

Author: nateprewitt

codegen/core/src/main/java/software/amazon/smithy/python/codegen/ClientGenerator.java

@@ -496,6 +496,8 @@ async def _handle_attempt(
                                     "Signer properties: %s",
                                     auth_option.signer_properties
                                 )
+                                context._identity = identity
+                                context._signer_properties = auth_option.signer_properties
                                 context._transport_request = await signer.sign(
                                     http_request=context.transport_request,
                                     identity=identity,

codegen/core/src/main/java/software/amazon/smithy/python/codegen/integrations/RestJsonProtocolGenerator.java

@@ -402,11 +402,21 @@ public void wrapEventStream(GenerationContext context, PythonWriter writer) {
         writer.addImport("smithy_json", "JSONCodec");
         writer.addImport("smithy_core.aio.types", "AsyncBytesReader");
         writer.addImport("smithy_core.types", "TimestampFormat");
+        writer.addImport("aws_sdk_signers", "AsyncEventSigner");
         writer.addStdlibImport("typing", "Any");
 
         writer.write("""
                 codec = JSONCodec(default_timestamp_format=TimestampFormat.EPOCH_SECONDS)
                 if has_input_stream:
+                    # TODO - Move this out of the RestJSON generator
+                    authorization_header = context.transport_request.fields.get("Authorization", "")
+                    signature = re.split("Signature=", authorization_header)[-1]
+                    signer = AsyncEventSigner(
+                        signer_properties=context._signer_properties
+                        identity=context._identity,
+                        prior_signature=hexlify(signature)
+                    )
+
                     if event_deserializer is not None:
                         return AWSDuplexEventStream[Any, Any, Any](
                             payload_codec=codec,
@@ -416,12 +426,14 @@ public void wrapEventStream(GenerationContext context, PythonWriter writer) {
                                 execution_context.transport_response.body  # type: ignore
                             ),
                             deserializer=event_deserializer,  # type: ignore
+                            signer=signer,  # type: ignore
                         )
                     else:
                         return AWSInputEventStream[Any, Any](
                             payload_codec=codec,
                             initial_response=operation_output,
                             async_writer=execution_context.transport_request.body,  # type: ignore
+                            signer=signer,  # type: ignore
                         )
                 else:
                     return AWSOutputEventStream[Any, Any](

packages/aws-sdk-signers/src/aws_sdk_signers/__init__.py

@@ -22,6 +22,7 @@
 __all__ = (
     "AsyncBytesReader",
     "AsyncSigV4Signer",
+    "AsyncEventSigner",
     "AWSCredentialIdentity",
     "AWSRequest",
     "Field",

packages/aws-sdk-signers/src/aws_sdk_signers/signers.py

@@ -780,16 +780,18 @@ async def _compute_payload_hash(
 
 
 class AsyncEventSigner:
+    
     def __init__(
         self,
         *,
         signing_properties: SigV4SigningProperties,
         identity: AWSCredentialIdentity,
+        intial_signature: bytes,
     ):
         self._signing_properties = signing_properties
         self._identity = identity
         self._prior_signature = initial_signature
-        self._signing_lock: asyncio.Lock = asyncio.Lock()
+        self._signing_lock = asyncio.Lock()
 
     async def sign_event(
         self,