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espressif / esp-mqtt

ESP32 mqtt component
Apache License 2.0
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wolfssl with esp-mqtt (IDFGH-1047) #116

Closed m0ot closed 5 years ago

m0ot commented 5 years ago

Hello everybody, I'm trying to implement esp-mqtt over wolfssl on esp32 in order to be able to create a tls1.3 connection between the board and the broker. However, I'm trying now to figure out how can I find the sent as well as received data of esp-mqtt? which are needed for the following wolfssl APIs:

void wolfSSL_write(WOLFSSL ssl, const void sent_data, int sz_of_sent_data) void wolfSSL_read(WOLFSSL ssl, void received_data, int sz_of_received_data)

Any ideas? thanks

david-cermak commented 5 years ago

Hi @m0ot

Please look at tcp_transport component in idf. esp-mqtt uses this api and specific transport layer is transparent for this library. All you need to do is to add a new transport, i.e. define specific functions for read, write, connect and assign them as function pointers to generic esp_transport api.

m0ot commented 5 years ago

thanks @david-cermak for your replay! I'm working on the mqtt_tcp example. Until now, I was able to successfully establish the wolfssl connection between the board and the broker (see here app_main.zip), but still missing the transporting of mqtt data under this secure connection. As I understood, all what I have to do is to edit the tcp_read, tcp_write, tcp_connect functions inside tcp_transport. Am I right? or I'm still missing something to understand it?

david-cermak commented 5 years ago

@m0ot It is a bit more complicated. Of course you can just alter tcp_read/tcp_write in tcp_transport just to get it working as a prove of concept.

Please look at https://github.com/espressif/esp-idf/blob/master/components/tcp_transport/transport_ssl.c#L199 initialisation of ssl transport actually sets specific functions defined in ssl_transport to common transport methods for read, write. Module esp_transport.h works something like a super-class with "virtual" methods for read, write, etc which are overridden in derived transport.

Correct solution would probably be a definition of a new transport which would init specific pointers to your wolfSSL_write and wolfSSL_read methods in esp_transport_set_func in for example esp_transport_handle_t esp_transport_wolfssl_init(). Then this library would init ssl transport in https://github.com/espressif/esp-mqtt/blob/idf/mqtt_client.c#L362 such as 

esp_transport_handle_t ssl = esp_transport_wolfssl_init();
m0ot commented 5 years ago

hi @david-cermak It just worked as expected. I had to create esp_transport_wolfssl and then define esp_transport_wolfssl_init() in mqtt_client.c. But I still have only one question: Do you have any ideas what would be the first step in order to add ( what I just developed) to MicroPython? I mean MicroPython uses also the Espressif IDF for esp32. I'm sure if this is would be possible or at least dependent with what I just developed.

david-cermak commented 5 years ago

Hi @m0ot

Thanks for the update about wolfssl, sounds interesting. Maybe, if you have some code to share, a link might be helpful also for others...

I cannot help with MicroPython, I'm afraid. General idea is probably to recompile the micropython itself with your mqtt implementation (with special function decoration for the API to be accessible from python -- per quick search found this example https://github.com/dhylands/micropython/commit/b801dbd39eb323494f946c13362f4957f5d7281b)

I would suggest to ask in the esp32 forum for more details.

m0ot commented 5 years ago

Hi @david-cermak Thanks for our replay. Actually, I wanted to contribute with the code on ESP-IDF project. But I'm not sure, if it's allowed to do that or to put it anywhere online.? Because ESP-IDF project licensed under Apache License 2.0 but wolfSSL licensed under both the GPLv2 as well as standard commercial licensing.

david-cermak commented 5 years ago

@m0ot Sorry for the late answer, Indeed including wolfSSL might introduce a license collision. Also wolfSSL is already included in 8266 SDK (https://github.com/espressif/ESP8266_RTOS_SDK/blob/master/components/esp-tls/esp_tls.c). It is integrated in esp-tls component (below the transport_ssl) and there're plans to port to esp32/IDF.

Please note the license info here https://github.com/espressif/ESP8266_RTOS_SDK/tree/master/components/ssl/wolfssl about using commercial rather than GPLv2 license for Espressif MCU products.

david-cermak commented 5 years ago

Closing as wolfSSL is already supported on IDF-master from https://github.com/espressif/esp-idf/commit/f7eaa5f9467da8261b7ed55413a1d2c6d6913817