netutils/libwebsockets: Remove hard-dependency on mbedTLS and enable websoket server

[tmedicci]

Summary

• examples/lws_echo: Add a simple websocket server example

  • Adds a simple websocket server example that echoes data back to the client using libwebsockets.

• netutils/libwebsockets: Fix error regarding building with CMake

  • Prior to this change, if an empty folder existed instead of the actual libwebsockets source, the build would fail. That was changed to
    check for an actual file instead, avoid such kind of errors.

• netutils/libwebsockets: Enable libwebsockets server

  • Enables building libwebsockets server based on a new Kconfig entry.

• netutils/libwebsockets: Remove hard dependency on mbedTLS

  • libwebsockets can be built without TLS support. To allow this, it was necessary to create a specific Kconfig option that enables TLS support if OPENSSL_MBEDTLS_WRAPPER is enabled. Otherwise, TLS is not supported (but libwebsockets can still be used with plain ws:// connections).

Impact

Impact on user: Yes. Enable using libwebsockets on simpler applications, including creating a websocket server.

Impact on build: Yes. Enable using both CMake and Make build system.

Impact on hardware: No.

Impact on documentation: No.

Impact on security: No.

Impact on compatibility: No.

Testing

This PR can be tested using, for instance, esp32p4-function-ev-board:ethernet defconfig using both CMake and Make:

Building

CMake-based

rm -rf build && cmake -B build -DBOARD_CONFIG=esp32p4-function-ev-board:ethernet -GNinja && kconfig-tweak --file build/.config --enable CONFIG_ALLOW_BSD_COMPONENTS && kconfig-tweak --file build/.config --enable CONFIG_DEV_URANDOM && kconfig-tweak --file build/.config --enable CONFIG_EVENT_FD && kconfig-tweak --file build/.config --enable CONFIG_PSEUDOFS_SOFTLINKS && kconfig-tweak --file build/.config --enable CONFIG_NETUTILS_LIBWEBSOCKETS && kconfig-tweak --file build/.config --enable CONFIG_NETUTILS_LIBWEBSOCKETS_SERVER && kconfig-tweak --file build/.config --enable CONFIG_EXAMPLES_LWS_ECHO && cmake --build build -t olddefconfig && cmake --build build && ESPTOOL_PORT=/dev/ttyACM0 cmake --build build -t flash

Make-based

make distclean && ./tools/configure.sh -S esp32p4-function-ev-board:ethernet && kconfig-tweak --enable CONFIG_ALLOW_BSD_COMPONENTS && kconfig-tweak --enable CONFIG_DEV_URANDOM && kconfig-tweak --enable CONFIG_EVENT_FD && kconfig-tweak --enable CONFIG_PSEUDOFS_SOFTLINKS && kconfig-tweak --enable CONFIG_NETUTILS_LIBWEBSOCKETS && kconfig-tweak --enable CONFIG_NETUTILS_LIBWEBSOCKETS_SERVER && kconfig-tweak --enable CONFIG_EXAMPLES_LWS_ECHO && make olddefconfig -s -j && make -j bootloader && make flash ESPTOOL_PORT=/dev/ttyACM0 -s -j$(nproc)

Running

The test is done by connecting the device to a known network and running the lws_echo application on NuttX and a test script on the host PC:

NuttX

Check the serial terminal using picocom (or any other similar software):

picocom -b 115200 /dev/ttyUSB1

Then, on NSH, run lws_echo &:

nsh> lws_echo &
lws_echo [7:100]
nsh> lws_echo: starting WebSocket echo server on port 9000
lws_echo: connect with ws://<device-ip>:9000 (subprotocol echo-protocol)

Host PC

Run the following Python script on the Host PC (adjust the device's IP address set at the uri var):

import asyncio
import websockets

async def test():
    uri = "ws://10.0.10.50:9000"
    async with websockets.connect(
        uri, subprotocols=["echo-protocol"], open_timeout=5
    ) as ws:
        msg = "Hello libwebsockets no-TLS!"
        await ws.send(msg)
        reply = await ws.recv()
        print(f"Sent: {msg}")
        print(f"Recv: {reply}")
        assert reply == msg
        print("PASS")

asyncio.run(test())

And run it with:

python websocket_test.py

Results

NuttX

[2019/11/29 00:00:45:3100] N: localhost: lws_create_context: LWS: 4.3.1-unknown, NET CLI SRV H1 H2 WS ConMon IPv6-absent
[2019/11/29 00:00:45:3100] N: localhost: __lws_lc_tag:  ++ [wsi|0|pipe] (1)
[2019/11/29 00:00:45:3100] N: localhost: __lws_lc_tag:  ++ [vh|0|localhost||9000] (1)
[2019/11/29 00:00:45:3200] N: [vh|0|localhost||9000]: lws_socket_bind: source ads 0.0.0.0
[2019/11/29 00:00:45:3300] N: localhost: __lws_lc_tag:  ++ [wsi|1|listen|localhost||9000] (2)
lws_echo: server running
[2019/11/29 00:00:54:9700] N: localhost: __lws_lc_taglws_echo: client connected
lws_echo: client disconnected
:  ++ [wsisrv|0|adopted] (1)
[2019/11/29 00:00:55:0200] N: localhost: __lws_lc_untag:  -- [wsisrv|0|adopted] (0) 50.000ms

Host PC

The Host PC will echo back the previously sent message:

$ python websocket_test.py
Sent: Hello libwebsockets no-TLS!
Recv: Hello libwebsockets no-TLS!
PASS