Building cURL: file descriptor issues

[IngwiePhoenix]

I am playing around with WASM and namely with the wasm3 project. It accepts modules compiled with -s WASM=1 -s SIDE_MODULE=1 which is quite neat.

So to play around with this, I built mbedTLS with Emscripten successfuly which is quite neat in and on itself! However, when then building CMake, I do get a successful build, but also this:

PS C:\Users\ingwi\work\curl\build.wasm> node .\src\curl.js -v http://192.168.0.1
*   Trying 192.168.0.1:80...
* Could not set TCP_NODELAY: Protocol not available
* Failed to set SO_KEEPALIVE on fd 3
* Immediate connect fail for 192.168.0.1: Host is unreachable
* Closing connection 0
curl: (7) Couldn't connect to server

Interesting. This IP is the one of my local access point, so it should most definitively exist. Also, domain name resolution also does not work. Something tells me this is something emcmake did not cover for me already.

So, what emcc flags do I have to use to get this working? I am quite positive the issue is not in cURL itself but rather the CFLAGS I have to give it. Currently, I use -s ASSERTIONS=0 to remove the sigaction() messages. (I got an astounding amount of those...).

[sbc100]

The support for sockets in emscripten is very limited .. because emscripten mostly targets the web which doesn't have a low level socket API. Right now we have some socket emulation that runs uses WebSockets and proxies all socket calls back to your server.

For more information see https://emscripten.org/docs/porting/networking.html

[IngwiePhoenix]

Interesting.

I came across something else that is sort of related - and that being signals:

$ node ssl_client1.js

  . Seeding the random number generator... ok
  . Loading the CA root certificate ... ok (0 skipped)
  . Connecting to tcp/localhost/4433...Calling stub instead of signal()
 failed
  ! mbedtls_net_connect returned -68

Last error was: -68 - NET - The connection to the given server / port failed

Looking at library_signal.js, I didn't get much wiser as to what exactly is missing for signal support? This is an mbedTLS test program and I wasn't running the accompaning server version, just to see what would happen.

Is there a way to support signals? And what exactly are they used for? Or can I just ignore this error and move on?

[sbc100]

Signals have various uses. You would need to dig into the specifics of your use case.

It unlikely signal will ever be a good match for the web since, and depending on the user case probably not a good match for node either.

[stale]

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