Networking can use allocators other than malloc. You mostly need arbitrary allocation for stuff like packet payload which can be arbitrary size (within limits). Many other structures, like IP headers, etc, can use much simpler, faster, safer allocators.
I know LwIP is pretty good around that sort of thing. It was just a little bit of a shock to see a lot of usage of malloc throughout ESP-IDF. But then it does have to handle Wi-fi, Bluetooth and more. It runs well though! And it does somewhat amortise its use of malloc to setup functions where possible.
One of the challenges I’ve had in the firmware work we’ve been doing, is the sheer amount of network-received runtime configuration. Makes statically allocating everything difficult. Not impossible of course, but our memory usage ends up sky high because we end up allocating buffers for the 70% of code that isn’t even going to be executed! So using “dynamic” allocation once when the runtime config determines this functionality is actually needed has worked reasonably well
Though it really reminds me of avoiding the GC in garbage collected languages, which is a little amusing to think about
