Adding user-agent information to request headers (#102)

Author: rccarper

include/aws/s3/private/s3_client_impl.h

@@ -16,6 +16,9 @@
 #include <aws/common/task_scheduler.h>
 #include <aws/http/connection_manager.h>
 
+/* TODO automate this value in the future to prevent it from becoming out-of-sync. */
+#define AWS_S3_CLIENT_VERSION "0.1.x"
+
 struct aws_http_connection;
 struct aws_http_connection_manager;
 

include/aws/s3/private/s3_util.h

@@ -19,6 +19,7 @@
 struct aws_allocator;
 struct aws_http_stream;
 struct aws_http_headers;
+struct aws_http_message;
 struct aws_event_loop;
 
 enum aws_s3_response_status {
@@ -38,20 +39,28 @@ struct aws_cached_signing_config_aws {
     struct aws_signing_config_aws config;
 };
 
-AWS_EXTERN_C_BEGIN
-
 extern const struct aws_byte_cursor g_s3_service_name;
 extern const struct aws_byte_cursor g_range_header_name;
 extern const struct aws_byte_cursor g_content_range_header_name;
 extern const struct aws_byte_cursor g_accept_ranges_header_name;
-
-AWS_S3_API
-extern const struct aws_byte_cursor g_acl_header_name;
-
 extern const struct aws_byte_cursor g_post_method;
 extern const struct aws_byte_cursor g_delete_method;
 extern const uint32_t g_s3_max_num_upload_parts;
 
+AWS_EXTERN_C_BEGIN
+
+AWS_S3_API
+extern const struct aws_byte_cursor g_s3_client_version;
+
+AWS_S3_API
+extern const struct aws_byte_cursor g_user_agent_header_name;
+
+AWS_S3_API
+extern const struct aws_byte_cursor g_user_agent_header_product_name;
+
+AWS_S3_API
+extern const struct aws_byte_cursor g_acl_header_name;
+
 AWS_S3_API
 extern const struct aws_byte_cursor g_host_header_name;
 
@@ -88,6 +97,9 @@ void replace_quote_entities(struct aws_allocator *allocator, struct aws_string *
 /* TODO could be moved to aws-c-common. */
 int aws_last_error_or_unknown(void);
 
+AWS_S3_API
+void aws_s3_add_user_agent_header(struct aws_allocator *allocator, struct aws_http_message *message);
+
 AWS_EXTERN_C_END
 
 #endif /* AWS_S3_UTIL_H */

source/s3_meta_request.c

@@ -123,6 +123,8 @@ int aws_s3_meta_request_init_base(
     meta_request->initial_request_message = options->message;
     aws_http_message_acquire(options->message);
 
+    aws_s3_add_user_agent_header(meta_request->allocator, meta_request->initial_request_message);
+
     if (aws_mutex_init(&meta_request->synced_data.lock)) {
         AWS_LOGF_ERROR(
             AWS_LS_S3_META_REQUEST, "id=%p Could not initialize mutex for meta request", (void *)meta_request);

source/s3_request_messages.c

@@ -427,7 +427,8 @@ struct aws_http_message *aws_s3_message_util_copy_http_message(
         if (multipart_upload_ops) {
             if (aws_byte_cursor_eq_c_str_ignore_case(&header.name, "host") ||
                 aws_byte_cursor_eq_c_str_ignore_case(&header.name, "x-amz-request-payer") ||
-                aws_byte_cursor_eq_c_str_ignore_case(&header.name, "x-amz-expected-bucket-owner")) {
+                aws_byte_cursor_eq_c_str_ignore_case(&header.name, "x-amz-expected-bucket-owner") ||
+                aws_byte_cursor_eq_ignore_case(&header.name, &g_user_agent_header_name)) {
                 if (aws_http_message_add_header(message, header)) {
                     goto error_clean_up;
                 }

source/s3_util.c

@@ -4,13 +4,15 @@
  */
 
 #include "aws/s3/private/s3_util.h"
+#include "aws/s3/private/s3_client_impl.h"
 #include <aws/auth/credentials.h>
 #include <aws/common/string.h>
 #include <aws/common/xml_parser.h>
 #include <aws/http/request_response.h>
 #include <aws/s3/s3.h>
 #include <aws/s3/s3_client.h>
 
+const struct aws_byte_cursor g_s3_client_version = AWS_BYTE_CUR_INIT_FROM_STRING_LITERAL(AWS_S3_CLIENT_VERSION);
 const struct aws_byte_cursor g_s3_service_name = AWS_BYTE_CUR_INIT_FROM_STRING_LITERAL("s3");
 const struct aws_byte_cursor g_host_header_name = AWS_BYTE_CUR_INIT_FROM_STRING_LITERAL("Host");
 const struct aws_byte_cursor g_range_header_name = AWS_BYTE_CUR_INIT_FROM_STRING_LITERAL("Range");
@@ -23,6 +25,10 @@ const struct aws_byte_cursor g_acl_header_name = AWS_BYTE_CUR_INIT_FROM_STRING_L
 const struct aws_byte_cursor g_post_method = AWS_BYTE_CUR_INIT_FROM_STRING_LITERAL("POST");
 const struct aws_byte_cursor g_delete_method = AWS_BYTE_CUR_INIT_FROM_STRING_LITERAL("DELETE");
 
+const struct aws_byte_cursor g_user_agent_header_name = AWS_BYTE_CUR_INIT_FROM_STRING_LITERAL("User-Agent");
+const struct aws_byte_cursor g_user_agent_header_product_name =
+    AWS_BYTE_CUR_INIT_FROM_STRING_LITERAL("CRTS3NativeClient");
+
 const uint32_t g_s3_max_num_upload_parts = 10000;
 const size_t g_s3_min_upload_part_size = MB_TO_BYTES(5);
 
@@ -249,3 +255,56 @@ int aws_last_error_or_unknown() {
 
     return error;
 }
+
+void aws_s3_add_user_agent_header(struct aws_allocator *allocator, struct aws_http_message *message) {
+    AWS_PRECONDITION(allocator);
+    AWS_PRECONDITION(message);
+
+    const struct aws_byte_cursor space_delimeter = AWS_BYTE_CUR_INIT_FROM_STRING_LITERAL(" ");
+    const struct aws_byte_cursor forward_slash = AWS_BYTE_CUR_INIT_FROM_STRING_LITERAL("/");
+
+    const size_t user_agent_product_version_length =
+        g_user_agent_header_product_name.len + forward_slash.len + g_s3_client_version.len;
+
+    struct aws_http_headers *headers = aws_http_message_get_headers(message);
+    AWS_ASSERT(headers != NULL);
+
+    struct aws_byte_cursor current_user_agent_header;
+    AWS_ZERO_STRUCT(current_user_agent_header);
+
+    struct aws_byte_buf user_agent_buffer;
+    AWS_ZERO_STRUCT(user_agent_buffer);
+
+    if (!aws_http_headers_get(headers, g_user_agent_header_name, &current_user_agent_header)) {
+        /* If the header was found, then create a buffer with the total size we'll need, and append the curent user
+         * agent header with a trailing space. */
+        aws_byte_buf_init(
+            &user_agent_buffer,
+            allocator,
+            current_user_agent_header.len + space_delimeter.len + user_agent_product_version_length);
+
+        aws_byte_buf_append_dynamic(&user_agent_buffer, &current_user_agent_header);
+
+        aws_byte_buf_append_dynamic(&user_agent_buffer, &space_delimeter);
+
+    } else {
+        AWS_ASSERT(aws_last_error() == AWS_ERROR_HTTP_HEADER_NOT_FOUND);
+
+        /* If the header was not found, then create a buffer with just the size of the user agent string that is about
+         * to be appended to the buffer. */
+        aws_byte_buf_init(&user_agent_buffer, allocator, user_agent_product_version_length);
+    }
+
+    /* Append the client's user-agent string. */
+    {
+        aws_byte_buf_append_dynamic(&user_agent_buffer, &g_user_agent_header_product_name);
+        aws_byte_buf_append_dynamic(&user_agent_buffer, &forward_slash);
+        aws_byte_buf_append_dynamic(&user_agent_buffer, &g_s3_client_version);
+    }
+
+    /* Apply the updated header. */
+    aws_http_headers_set(headers, g_user_agent_header_name, aws_byte_cursor_from_buf(&user_agent_buffer));
+
+    /* Clean up the scratch buffer. */
+    aws_byte_buf_clean_up(&user_agent_buffer);
+}

tests/CMakeLists.txt

@@ -64,6 +64,10 @@ add_net_test_case(test_s3_bad_endpoint)
 add_net_test_case(test_s3_put_object_clamp_part_size)
 add_net_test_case(test_s3_replace_quote_entities)
 add_net_test_case(test_s3_different_endpoints)
+add_test_case(test_add_user_agent_header)
+add_net_test_case(test_s3_auto_ranged_get_sending_user_agent)
+add_net_test_case(test_s3_auto_ranged_put_sending_user_agent)
+add_net_test_case(test_s3_default_sending_meta_request)
 
 add_test_case(test_get_existing_compute_platform_info)
 add_test_case(test_get_nonexistent_compute_platform_info)