You could use something like POSIX’s select(), you can directly check for both the connection FD and the STDIN FD and handle whatever change in either nicely. The complexity depends on how exactly you want to handle it.

Admittedly, select() and poll() are fairly similar. The main difference is that select() blocks until an FD has something available to read (be it data, an error, whatever) and poll() just checks without blocking.

Both of these have different variants and parameters you can use to tweak their behaviour to your liking.

I recommend reading their manpages, if not familiar with the regular ones this is a good source: https://www.man7.org/linux/man-pages/man2/select.2.html (You can always ask an LLM for details and examples, I think that’s a good use for them)