Add 'Content-Length: 0' header on multipart upload creation (#428)

Co-authored-by: Jonathon Belotti <jonathon@modal.com>

source/s3_request_messages.c

@@ -245,7 +245,7 @@ struct aws_http_message *aws_s3_ranged_get_object_message_new(
     return message;
 }
 
-/* Creates a create-multipart-upload request from a given put objet request. */
+/* Creates a create-multipart-upload request from a given put object request. */
 struct aws_http_message *aws_s3_create_multipart_upload_message_new(
     struct aws_allocator *allocator,
     struct aws_http_message *base_message,
@@ -291,6 +291,11 @@ struct aws_http_message *aws_s3_create_multipart_upload_message_new(
         }
     }
 
+    struct aws_byte_cursor content_length_cursor = aws_byte_cursor_from_c_str("0");
+    if (aws_http_headers_set(headers, g_content_length_header_name, content_length_cursor)) {
+        goto error_clean_up;
+    }
+
     aws_http_message_set_request_method(message, g_post_method);
     aws_http_message_set_body_stream(message, NULL);
 

tests/s3_request_messages_tests.c

@@ -680,14 +680,18 @@ static int s_test_s3_create_multipart_upload_message_new(struct aws_allocator *a
 
     ASSERT_SUCCESS(s_test_http_message_request_method(create_multipart_upload_message, "POST"));
     ASSERT_SUCCESS(s_test_http_message_request_path(create_multipart_upload_message, &expected_create_path));
+
+    const struct aws_byte_cursor header_exclude_exceptions[] = {
+        AWS_BYTE_CUR_INIT_FROM_STRING_LITERAL("Content-Length"),
+    };
     ASSERT_SUCCESS(s_test_http_headers_match(
         allocator,
         original_message,
         create_multipart_upload_message,
         g_s3_create_multipart_upload_excluded_headers,
         g_s3_create_multipart_upload_excluded_headers_count,
-        NULL,
-        0));
+        header_exclude_exceptions,
+        AWS_ARRAY_SIZE(header_exclude_exceptions)));
 
     aws_http_message_release(create_multipart_upload_message);
     aws_http_message_release(original_message);