AWS IoT Over-the-air Update Library

API Documentation Pages for current and previous releases of this library can be found here

The OTA library enables you to manage the notification of a newly available update, download the update, and perform cryptographic verification of the firmware update. Using the library, you can logically separate firmware updates from the application running on your devices. The OTA library can share a network connection with the application, saving memory in resource-constrained devices. In addition, the OTA library lets you define application-specific logic for testing, committing, or rolling back a firmware update. The library supports different application protocols like Message Queuing Telemetry Transport (MQTT) and Hypertext Transfer Protocol (HTTP), and provides various configuration options you can fine tune depending on network type and conditions. This library is distributed under the MIT Open Source License.

This library has gone through code quality checks including verification that no function has a GNU Complexity score over 10. This library has also undergone static code analysis from Coverity static analysis.

See memory requirements for this library here.

AWS IoT Over-the-air Update Library v3.4.0 source code is part of the FreeRTOS 202210.00 LTS release.

AWS IoT Over-the-air Update Library v3.3.0 source code is part of the FreeRTOS 202012.01 LTS release.

Upcoming Changes

Intended for release in Q4 2023, a major version update of this library will make it compliant with the FreeRTOS “core” branded libraries design goal of being free of any dependencies other than the C library. The monolithic design of the existing OTA library doesn't make it easy to make use case specific modifications, such as changing the OTA update source. The new major version will refactor the library, amongst other things, to increase modularity and simplify the use of any firmware source or communication mechanism, both supported by AWS and not.

While the old version of this library will remain available, we will not be developing it further and will instead focus on the newer major versions going forward. To see our current progress towards this goal, please see FreeRTOS/Labs-Project-ota-example-for-aws-iot-core.

AWS IoT Over-the-air Updates Config File

The AWS IoT Over-the-air Updates library exposes configuration macros that are required for building the library. A list of all the configurations and their default values are defined in ota_config_defaults.h. To provide custom values for the configuration macros, a custom config file named ota_config.h can be provided by the user application to the library.

By default, a ota_config.h custom config is required to build the library. To disable this requirement and build the library with default configuration values, provide OTA_DO_NOT_USE_CUSTOM_CONFIG as a compile time preprocessor macro.

Building the Library

The otaFilePaths.cmake file contains the information of all source files and the header include paths required to build the AWS IoT Over-the-air Updates library.

As mentioned in the previous section, either a custom config file (i.e. ota_config.h) OR the OTA_DO_NOT_USE_CUSTOM_CONFIG macro needs to be provided to build the AWS IoT Over-the-air Updates library.

For a CMake example of building the AWS IoT Over-the-air Updates library with the otaFilePaths.cmake file, refer to the coverity_analysis library target in the test/CMakeLists.txt file.

Building Unit Tests

Checkout CMock Submodule

By default, the submodules in this repository are configured with update=none in .gitmodules to avoid increasing clone time and disk space usage of other repositories (like AWS IoT Device SDK for Embedded C that submodules this repository).

To build unit tests, the submodule dependency of CMock is required. Use the following command to clone the submodule:

git submodule update --checkout --init --recursive test/unit-test/CMock source/dependency/coreJSON

Platform Prerequisites

• For building the library, CMake 3.13.0 or later and a C90 compiler.
• For running unit tests, Ruby 2.0.0 or later is additionally required for the CMock test framework (that we use).
• For running the coverage target, gcov and lcov are additionally required.

Steps to build unit tests

1. Go to the root directory of this repository. (Make sure that the CMock submodule is cloned as described above.)

2. Run the cmake command: cmake -S test -B build

3. Run this command to build the library and unit tests: make -C build all

4. The generated test executables will be present in build/bin/tests folder.

5. Run cd build && ctest to execute all tests and view the test run summary.

Migration Guide

How to migrate from v2.0.0 (Release Candidate) to v3.4.0

The following table lists equivalent API function signatures in v2.0.0 (Release Candidate) and v3.4.0 declared in ota.h

v2.0.0 (Release Candidate)	v3.4.0	Notes
OtaState_t OTA_Shutdown( uint32_t ticksToWait );	OtaState_t OTA_Shutdown( uint32_t ticksToWait, uint8_t unsubscribeFlag );	unsubscribeFlag indicates if unsubscribe operations should be performed from the job topics when shutdown is called. Set this as 1 to unsubscribe, 0 otherwise.

How to migrate from version 1.0.0 to version 3.4.0 for OTA applications

Refer to OTA Migration document for the summary of updates to the API. Migration document for OTA PAL also provides a summary of updates required for upgrading the OTA-PAL to work with v3.4.0 of the library.

Porting

In order to support AWS IoT Over-the-air Updates on your device, it is necessary to provide the following components:

1. Port for the OTA Portable Abstraction Layer (PAL).

2. OS Interface

3. MQTT Interface

For enabling data transfer over HTTP dataplane the following component should also be provided:

1. HTTP Interface

NOTE When using OTA over HTTP dataplane, MQTT is required for control plane operations and should also be provided.

CBMC

To learn more about CBMC and proofs specifically, review the training material here.

The test/cbmc/proofs directory contains CBMC proofs.

In order to run these proofs you will need to install CBMC and other tools by following the instructions here.

CBMC Locally

To run a single CBMC proof locally, you can build the Makefile in any of the CBMC proofs. The Makefile is located in the test/cbmc/proof/<the proof you want>/ directory.

Running make will produce a HTML-based report nearly identical to the one produced by the CI step.

A couple notes about CBMC Proofs

• macOS doesn't implement POSIX message queues (mqueue.h);
• It is possible that macOS fails to recognize your loop unwinding identifiers for function from the C standard libraries. For this case, you'll want to use the __builtin___<function>_chk identifier, e.g., instead of using memcpy add __builtin___memcpy_chk.
  • For example, the requestJob_Mqtt proof fails on macOS with the following error:

Loop unwinding failures
[trace] __builtin___strncpy_chk.unwind.0 in line 36 in file <builtin-library-__builtin___strncpy_chk>

To solve this issue, replace strncpy with __builtin___strncpy_ch on this line.

Reference examples

Please refer to the demos of the AWS IoT Over-the-air Updates library in the following location for reference examples on POSIX and FreeRTOS:

Platform	Location
POSIX	AWS IoT Device SDK for Embedded C
FreeRTOS	FreeRTOS/FreeRTOS
FreeRTOS	FreeRTOS AWS Reference Integrations

Documentation

Existing Documentation

For pre-generated documentation, please see the documentation linked in the locations below:

Location
AWS IoT Device SDK for Embedded C
FreeRTOS.org

Note that the latest included version of coreMQTT may differ across repositories.

Generating documentation

The Doxygen references were created using Doxygen version 1.9.2. To generate the Doxygen pages, please run the following command from the root of this repository:

doxygen docs/doxygen/config.doxyfile

Contributing

See CONTRIBUTING.md for information on contributing.