| // Copyright 2016 The Fuchsia Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "message.h" |
| |
| #include <stdint.h> |
| |
| _Static_assert(sizeof(mojo_message_header_t) == 16u, "mojo_message_header_t should be 16 bytes"); |
| |
| _Static_assert(sizeof(mojo_message_header_with_request_id_t) == 24u, |
| "mojo_message_header_t should be 24 bytes"); |
| |
| bool mojo_validate_message_header(const mojo_struct_header_t* header, size_t size) { |
| if (header->num_bytes < sizeof(mojo_message_header_t) || size < sizeof(mojo_message_header_t) || |
| size > UINT32_MAX) { |
| return false; |
| } |
| |
| const mojo_message_header_t* message_header = (const mojo_message_header_t*)header; |
| |
| // Message expects response and message is response flags are mutually |
| // exclusive. |
| if ((message_header->flags & MOJO_MESSAGE_HEADER_FLAGS_EXPECTS_RESPONSE) && |
| (message_header->flags & MOJO_MESSAGE_HEADER_FLAGS_IS_RESPONSE)) { |
| return false; |
| } |
| |
| if (header->version == 0u) { |
| if (header->num_bytes != sizeof(mojo_message_header_t)) { |
| return false; |
| } |
| |
| // Version 0 has no request id and should not have either of these flags. |
| if ((message_header->flags & MOJO_MESSAGE_HEADER_FLAGS_EXPECTS_RESPONSE) || |
| (message_header->flags & MOJO_MESSAGE_HEADER_FLAGS_IS_RESPONSE)) { |
| return false; |
| } |
| } else if (header->version == 1u) { |
| if (header->num_bytes != sizeof(mojo_message_header_with_request_id_t)) { |
| return false; |
| } |
| } |
| // Accept unknown versions of the message header to be future-proof. |
| |
| return true; |
| } |