Get a HTTP/CGI/SSI server working

[iamtheband]

Hi Earle/all,

I'm porting some code from a "crude" Pi Pico SDK build to the Arduino-Pico framework. Part of that code is a HTTP server that is built on the lwIP stack in the SDK.

When I build the ported code I get a linker error:

/home/virgult/.arduino15/packages/rp2040/tools/pqt-gcc/4.0.1-8ec9d6f/bin/../lib/gcc/arm-none-eabi/14.2.0/../../../../arm-none-eabi/bin/ld: /home/virgult/.cache/arduino/sketches/E1BE167AFC67A0B64AF615EC90CCAA45/sketch/src/web/WebInterface.cpp.o: in function `_Z15WebInterfaceRunv':
/home/virgult/Dev/Arduino/PicoMEML/src/web/WebInterface.cpp:52:(.text._Z15WebInterfaceRunv+0x2): undefined reference to `httpd_init'
/home/virgult/.arduino15/packages/rp2040/tools/pqt-gcc/4.0.1-8ec9d6f/bin/../lib/gcc/arm-none-eabi/14.2.0/../../../../arm-none-eabi/bin/ld: /home/virgult/.cache/arduino/sketches/E1BE167AFC67A0B64AF615EC90CCAA45/sketch/src/web/cgi.cpp.o: in function `_Z8cgi_initv':
/home/virgult/Dev/Arduino/PicoMEML/src/web/cgi.cpp:250:(.text._Z8cgi_initv+0x6): undefined reference to `http_set_cgi_handlers'
/home/virgult/.arduino15/packages/rp2040/tools/pqt-gcc/4.0.1-8ec9d6f/bin/../lib/gcc/arm-none-eabi/14.2.0/../../../../arm-none-eabi/bin/ld: /home/virgult/.cache/arduino/sketches/E1BE167AFC67A0B64AF615EC90CCAA45/sketch/src/web/ssi.cpp.o: in function `_Z8ssi_initv':
/home/virgult/Dev/Arduino/PicoMEML/src/web/ssi.cpp:66:(.text._Z8ssi_initv+0x3c): undefined reference to `http_set_ssi_handler'

You can have a look at the referenced files e.g. here:
https://github.com/MusicallyEmbodiedML/PicoMEML/blob/cgi/src/web/WebInterface.cpp

My hunch is that the relevant SDK library, called pico_lwip_http, isn't exposed by Arduino-Pico. In our CMake build, we'd have something like this in our CMakeLists:

target_link_libraries(pico_interface_fmsynth pico_stdlib hardware_adc pico_multicore 
        pico_cyw43_arch_lwip_threadsafe_background
        pico_lwip_http)

Can someone point me towards good instructions to rebuild the SDK with that pico_lwip_http dependency? Instinctively, I would add pico_lwip_http to this file:

arduino-pico/tools/libpico/CMakeLists.txt

Line 229 in 8caa590

pico_lwip

But then I'm not sure how to rebuild the SDK specifically for Arduino.

Thanks everyone!

[earlephilhower]

https://github.com/earlephilhower/arduino-pico/tree/master/tools#libpicomake-libpicosh

GitHub can rebuild it using actions, too, on a fork of this repo.