Below you will find the wolfMQTT ChangeLog documenting the changes that took place with each release of wolfMQTT since the project’s beginning in 2015.

wolfMQTT 1.12.0


  • Allow MqttClient_WaitType to return MQTT_CODE_CONTINUE with MT (PR #283)
  • Fix decoding user property and add example (PR #282)
  • Fix issue with MqttClient_Publish_WriteOnly not waiting properly for ACK (PR #281)
  • Fix MQTTv5 disconnect with props (PR #279)
  • Add new publish write only API for multi-threading (PR #277)
  • Fix for multithreaded cancel (PR #276)
  • MQTT-SN Add disconnect_cb when disconnect recv from broker; Fix PUB ACK return status handling (PR #274)
  • Enable TLS1.3 in examples (PR #273)
  • Adding windows github actions build test (PR #272)

wolfMQTT 1.11.0


  • Return correct error code in SN_Client_Connect (PR #268)
  • Removing unsupported TLS and SNI options in sn-client (PR #266)
  • Fixes for multithreading with non-blocking (PR #252)
  • Doxygen work removing depreciated command and fixing other warnings (PR #264)
  • Fix overwriting TLS error in connect (PR #259)
  • Add GitHub Actions (PR #256 #260 #263)
  • Fix wm_Sem on Windows (PR #255 #261)
  • Fix scripts for host without mosquitto (PR #257 #265)
  • Trim whitespace and convert tab to spaces (PR #251)
  • Refactor of write length (PR #250)
  • Fixes for publish edge cases (PR #248)
  • Remove unused sub_id element, add support for local test broker (PR #249)
  • Fix to make sure MqttClient_DecodePacket called in all cases (PR #246)


  • Known bug with multithread and without nonblocking enabled in this release.

wolfMQTT 1.10.0


  • Improve FALL_THROUGH macro logic for XC32. (PR #227)
  • Fix potential NULL printf in MqttSocket_Connect with verbose debug enabled. (PR #229)
  • Fix non-block chunked transfer. (PR #230)
  • Fix QoS responses (PR #231, 240)
  • Fix MQTTv5 property handling (PR #232, 233, 234, 236, 238, 241)
  • Fix fuzzing test issues (PR #242)

wolfMQTT 1.9.0


  • Fixes for Sensor Network client (PR #204, 214, 219)
  • Fixes for non-blocking (PR #205)
  • Fixes for multithread (PR #207, 209, 211, 218)
  • Fix for MQTTv5 publish response handling (PR #224, 220)
  • Fix subscribe return code list (PR #210)
  • Fix switch statement fallthrough on other toolchains (PR #225)
  • Add HiveMQ Cloud capability with SNI feature (PR #222)
  • Add ability to publish files from example client, fix chunked publish (PR# 223)

wolfMQTT 1.8.0


  • Fixes for non-blocking in WIN32 and large payload (PR #202)
  • Make TLS IO callback functions public (PR #201)
  • Bug fixes (PR #186, 188, 189, 193, 196, 199, 200)
  • Update default test broker (PR #194)
  • MQTT-SN fixes for multithread and register topic name (PR #185, 190)
  • Fix multi-thread to use pthread mutex with condition (PR #183)
  • Fix for WIN thread create macro (PR #182)
  • Use options.h with Arduino build (PR #181)
  • Use MqttClient_Ping_ex instead of MqttClient_Ping in examples (PR #179)
  • Fixes for building with MinGW (PR #178)
  • MQTT-SN support for multithread (PR #176)
  • TLS mutual auth in client examples (PR #175)
  • MQTT-SN feature enhancements (PR #173)
  • Add runtime message option to client (PR #171)

wolfMQTT 1.7.0


  • Fix for publish with short topic name and example. (PR #169)
  • Add MqttProps_ShutDown(). Fix MqttProp leaks(PR #167)
  • Multithread fixes. (PR #166)
  • Fix buffer overrun in strcpy(). Fix logic around getaddrinfo(). (PR #165)
  • Fix MqttClient_WaitType for nonblock mode. (PR #164)
  • Change anon union for ARMv6 error. (PR #163)
  • Fix for publish large payload. (PR #162)
  • Fixing LWT prop and allow null LWT. (PR #161)
  • Fix for receive timeout in mqttsimple example. (PR #158)

wolfMQTT 1.6.0


  • Fixes to improve buffer size checking when using a small tx or rx buffer. (PR #137)
  • Fix for MQTT v5 issue with using wrong property free. (PR #152)
  • Refactor of the thread locking to use binary semaphore, which resolves issue with thread synchronization. (PR #146)
  • Improved multi-thread example exit (ctrl+c). Use internal pipe to wake "select()" and use semaphore signal to "wake" ping thread. (PR #146)
  • Adjust multi-threading use case to use separate thread for ping keep-alive. (PR #146)
  • Added simple standalone MQTT client example. (PR #138)
  • Added include for "user_settings.h" when `WOLFMQTT_USER_SETTINGS` is defined. (PR #138)
  • Added broker compatibility list (PR #145)
  • Added protocol version API's. (PR #152)
  • Added multithread example for Windows and Visual Studio. (PR #146)
  • Made protocol level a run time option (PR #147)
  • Remove obsolete "sched_yield" call. (PR #146)
  • Remove deprecated call to `wolfSSL_set_using_nonblock()` (PR #148)
  • Sync automake fixes from wolfSSL to wolfMQTT. (PR #150)
  • Moved `MAX_PACKET_ID` to library. (PR #138)

wolfMQTT 1.4.0


  • Fixes for non-blocking and multi-threading edge cases. (PR #130)
    • Improved logic for processing objects from different threads.
    • Improved network connect/read to handle runtime option for block/non-block.
    • Improved examples to support adding random hex string to client_id and topic name when "-T" option is used.
    • Fix for test scripts to check non-zero return code.
    • Enabled the mqttclient, multithread and wiot examples when non-blocking is enabled.
    • Added encode debug log messages when WOLFMQTT_DEBUG_CLIENT is defined.
    • Added thread logging when WOLFMQTT_DEBUG_THREAD is defined with multi-threading support enabled.
  • Fixes for Visual Studio project (PR #122)
    • Improvements to catch use of socket file descriptor before its been created/opened.
    • Improved handling for Windows socket want write.
    • Added library references to wolfSSL project.
    • Adjusted include to have IDE/WIN for user_settings.h.
  • Fixes for Visual Studio conversion warning (PR #128)
  • Fix visibility warnings in Cygwin (PR #127)
  • Fix global declaration conflicts for CentOS (PR #133)
  • Fix Microchip Harmony for mqtt_socket.c with non-blocking and errno.h (PR #135)
  • Fix to not return from MqttClient_WaitMessage if response from another thread (PR #129)
  • Refactor of the multi-threading code to better handle edge case and state for non-blocking (PR #126)
    • Fixes for multi-thread handling of ack's when processing.
    • Refactor to use stat from own struct, not shared msg->stat.
    • Eliminated use of client->msg except for MqttClient_WaitMessage.
    • Fixes to restore "state" after performing MqttClient operation.
    • Refactor of publish read and write payload.
    • Improvements to multithread example.
    • Refactor of the SN code to support new object type and unique state for future multi-thread support.
    • Added build option TEST_NONBLOCK to force testing non-blocking edge cases.
    • Fix for fwpush getting stuck in stop loop on Ctrl+c exit.
  • Update Azure login and default broker (PR #131)

wolfMQTT 1.3.0


  • Fix `fwpush` example to use filename option `-f`. (PR #117)
  • Added multiple thread support using `--enable-mt` or `WOLFMQTT_MULTITHREAD`. (PR #115)
  • Fix for `MQTT_DATA_TYPE_BINARY` data length encoded twice. (PR #112)
  • Fix to clear local structures for subscribe and unsubscribe ACK's. (PR #112)
  • Fix for `SN_Encode_Unsubscribe` using wrong data type for topic name ID. (PR #110)
  • Add `WOLFSSL_USER_SETTINGS` to VS project files. (PR #109)
  • Fixes for using RTCS in `mqttnet.c` socket example code. (PR #108)
  • Fix MQTT-SN decode publish parsing and QoS2 response. (PR #107)
  • Make MqttSocket_TlsSocket callbacks public. (PR #104)
  • Improved the disconnect network error callback example. (PR #102)
  • Add MQTT context information to socket callback examples. (PR #101)
  • Initialize subscribe state to `MQTT_MSG_BEGIN`. (PR #99)
  • Fix for Harmony possible circular include issue. (PR #98)

wolfMQTT 1.2.0


  • Added MQTT Sensor Network (SN) client support (--enable-sn or WOLFMQTT_SN).
  • Added MQTT v5.0 support with (--enable-mqtt5 or WOLFMQTT_V5).
  • Added property callback support (MQTT v5.0 only). Enabled with --enable-propcb or WOLFMQTT_PROPERTY_CB).
  • Fix for Harmony NetConnect function incorrectly checking EWOULDBLOCK. Fixes issue #88.
  • Fix to reset the TLS ctx and ssl pointers when they have been free'd.
  • Add way to pass custom context to the wolfMQTT TLS verify callback example mqtt_tls_verify_cb.
  • Create nonblocking mqttclient example ./examples/nbclient/nbclient.
  • Add support for publishing in smaller chunks using new API MqttClient_Publish_ex.
  • Added simplified Microchip Harmony wolfMQTT network callback example.

wolfMQTT 1.1.0


Version 1.1.0 of wolfMQTT contains bug fixes and new features including:

  • Fixed case when `use_tls` was requested but TLS feature not compiled in. (PR #57)
  • Fixed non-blocking issue that caused out of buffer error if not all of packet were received. (PR #65)
  • Fixed non-blocking mode issue that was sending multiple connect requests for examples. (PR #65)
  • Fixed non-blocking issue with ping keep alive in examples. (PR #68)
  • Fixed the Arduino example with `ENABLE_MQTT_TLS` defined (PR #78)
  • Added support for FreeRTOS TCP in wolfMQTT. (PR #58)
  • Added `README.md` section for building wolfMQTT. (PR #63)
  • Added new option to enable verbose logging `./configure --enable-debug=verbose`. (PR #65)
  • Added support for disconnect callback using `WOLFMQTT_DISCONNECT_CB` or `./configure --enable-discb`. (PR #69)
  • Added `WOLFMQTT_LOCAL` to internal API's for hidden visibility. (PR #73)
  • Added include for `wolfmqtt/options.h`. (PR #79)
  • Added IBM Watson IoT example (see `./examples/wiot/wiot`). (PR #80)
  • Updated the autoconf M4 files and added generation of `./configure` options to `wolfmqtt/options.h`. (PR #71)
  • Improved the message callback to support a custom context per message. (PR #62)
  • Improved the non-blocking unsubscribe handling in mqttclient example for timeout. (PR #65)

wolfMQTT 1.0.0


Version 1.0.0 of wolfMQTT contains bug fixes and new features including:

  • Fixed `MqttClient_WaitMessage` to use provided `timeout_ms` arg. With TLS enabled it was using the `MqttClient_Init` `cmd_timeout_ms` arg. Thanks PeterL for that report.
  • Fixed cast warnings when building with Visual Studio.
  • Cleanup socket code to use existing `SOCK_CLOSE` for `NetDisconnect`.
  • Cleanup to move the `sockRc` into the `MqttTls` struct, since it only applies when TLS is enabled.
  • Added configure option to disable error strings for reduced code size (`./configure disable-errorstrings` or `#define WOLFMQTT_NO_ERROR_STRINGS`).
  • Added support for ChibiOS.

wolfMQTT 0.14.0


Version 0.14.0 of wolfMQTT contains bug fixes and new features including:

  • Fixed non-blocking connect to check for `EINPROGRESS` for all platforms (not just Harmony)
  • Fixed buffer overflow position check on read/write
  • Fixed typo on internal packet function `MqttDecode_ConnectAck`
  • Fixed the socket close for Harmony to use `closesocket`
  • Fixed non-blocking connect where `WOLFMQTT_NO_STDIO` is defined
  • Fixed GCC 7's new fall-through check
  • Added check for EAGAIN in non-blocking mode (was only EWOULDBLOCK)
  • Added non-blocking support for write operations when `WOLFMQTT_NONBLOCK` is defined
  • Added support for DH and setting the default minimum key bits
  • Added support for keep-alive ping when using non-blocking mode
  • Improvements to example TLS callback handling of return code failures
  • Improvements and fixes to Visual Studio projects
  • Enhancement to adjust wolfSSL options.h include based on `WOLFSSL_USER_SETTINGS`.

wolfMQTT 0.13.0


Version 0.13.0 of wolfMQTT contains bug fixes and new features including:

  • Fixed issue with `msg->stat` in non-blocking.
  • Fixed Arduino library build.
  • Fixed examples with non-blocking (--enable-nonblock).
  • Enhancement to pass network callback return codes through context when using TLS.
  • Added option to disable the blocking timeouts for `select()` using `--disable-timeout` (or `WOLFMQTT_NO_TIMEOUT`).
  • Added option to disable STDIN/fgets capture for examples using `--disable-stdincap` (or `WOLFMQTT_NO_STDIN_CAP`)
    Refactor to use new `MQTT_CODE_STDIN_WAKE` return code for examples using STDIN to send publish messages (normal blocking mode only).

wolfMQTT 0.12


Version 0.12 of wolfMQTT contains bug fixes and new features including:

  • Fixes issue with read timeout in non-blocking mode with TLS enabled being teated as socket error.
  • Fixed issue with “msg->stat” not getting reset on failure or timeout.
  • Fix to not link libwolfssl with ./configure --disable-tls.
  • Added AWS IoT Example and test script.

wolfMQTT 0.10


Version 0.10 of wolfMQTT contains bug fixes and new features including:

  • Enabled big endian support.
  • Fixes for building with Visual Studio.

wolfMQTT 0.8


Version 0.8 of wolfMQTT contains bug fixes and new features including:

  • Fixed stdin capture bug and improved signal (ctrl+c) handling.
  • Added Azure IoT hub MQTT client example.
  • Added support for MQX / RTCS.
  • Added "--disable-tls" and "--disable-examples" configure options.
  • Added comment about max packet size.
  • Added example for how to load a client certificate to mqttclient example.
  • Added return code for firmware and azure examples that are not compiled in due to older / incompatible version of wolfSSL.
  • Moved the support for custom printf/line endings into the mqtt_types.h for use throughout the project.
  • Updated README.md with information about the examples.

wolfMQTT 0.6


Version 0.6 of wolfMQTT contains bug fixes and new features including:

  • Fixes to support MinGW compiler.
  • Fixed bug with include of the wolfSSL include of options.h.
  • Fix to properly handle negative return code from wc_SignatureGetSize.
  • Added Arduino IDE example in `IDE/ARDUINO`. See `IDE/ARDUINOREADME.md` for details.
  • Added example UART interface for wolfMQTT. See `examples/mqttuart.c`.
  • Added the ability to pass additional arguments to the scripts. Example: `./scripts/client.test "-h localhost"`

wolfMQTT 0.4


Version 0.4 of wolfMQTT contains bug fixes and new features including:

  • Fixed bug with subscribe not populating acknowledgment return code(s) properly.
  • Fixed build error if using wolfSSL 3.7.1 or older due to missing signature.c/.h wrappers. This fix disables the firmware examples if the wolfSSL version isn't greater than 3.7.1.
  • Fix to ensure `topic_name` pointer is reset when publish callback message is not new `msg_new = 0`.
  • Fixes to suppress possible warning "Value stored to [] is never read".
  • Fixed firmware example to trap case where file isn't found.
  • Fixed possible ./autogen.sh error with missing "config.rpath".
  • Fixed Windows issue with SetConsoleCtrlHandler incorrectly reporting error.
  • Fixed issue with Visual Studio 2015 wolfssl.lib reference.
  • Fixed build errors with G++ (./configure CC=g++).
  • Fixed "FirmwareHeader" to use WOLFMQTT_PACK macro.
  • Added helper macro's and comments for topic names/filters.
  • Added TLS certification verification reference implementation to examples.
  • Updated the topic names in examples to use "wolfMQTT/example/".
  • Added QoS level to example console output.
  • Added memset to initialize some of the example stack variables.
  • Removed the LWT from the firmware examples.
  • Added retain flag "-r" option on the "fwpush" example.
  • Updated the examples to use macros for all memory and string functions, so they are more portable.
  • Added Visual Studio projects for "fwpush" and "fwclient".

wolfMQTT 0.3


Version 0.3 of wolfMQTT contains bug fixes and new features including:

  • Fixes bug with first byte of payload being null'd if QoS level was 0.
  • Fixed issue with stdint types (uint#_t) being used.
  • Fixes for remaining length encoding/decoding for large packets.
  • Added support for large payloads using new message callback flags `msg_done` and `msg_new` along with MqttMessage `buffer_pos` and `buffer_len`.
  • Added example for secure firmware upgrade. Uses the MQTT client library to push a signed payload `fwpush` to a broker, then uses another client `fwclient` to receive the signed payload and verify its signature using a provided public key.

wolfMQTT 0.2


This is the first release of wolfMQTT.

Please see the README included in the wolfMQTT download for build instructions and API reference.