Turning off gateway options in DHCP when operating Pico W in AP mode.

[the-maldridge]

The title pretty much sums it up, but I'm trying to figure out how to suppress handing out a default gateway when operating in AP mode. I can see in https://github.com/earlephilhower/arduino-pico/blob/master/libraries/WiFi/src/dhcpserver/dhcpserver.c where the options get defined and written, but I don't see any entrypoints to that code to influence what options get sent. I'm ultimately trying to work out how to disable both the gateway option and the DNS option, since I want to be able to connect to a network the Pico is presenting from a device with two PHYs and if the Pico offers these parameters it will interfere with the working network configuration on such a host.

[earlephilhower]

There are no APIs presently to support this, but if you want to try your hand at defining them and making a PR I'd be happy to take a look at it! Probably just need to isolate

arduino-pico/libraries/WiFi/src/dhcpserver/dhcpserver.c

Lines 278 to 279 in c670f66

	opt_write_n(&opt, DHCP_OPT_ROUTER, 4, ip_2_ip4(&d->ip)); // aka gateway; can have multiple addresses
	opt_write_n(&opt, DHCP_OPT_DNS, 4, ip_2_ip4(&d->ip)); // can have multiple addresses

[the-maldridge]

Hmm, I'm happy to try my hand at making a PR. Do you have strong opinions on how you might want this extension of the API to look?

[earlephilhower]

There's already WiFi.config() call which lets you set GW and DNS, maybe that could be used/overridden here to keep things symmetric?

[the-maldridge]

I've got a patch in progress, but I'm running into trouble testing it. I followed the instructions to reinstall everything from git, but the arduino-cli is now complaining that it can't find a platform rp2040:rp2040 installed. Is there some extra step after cloning everything into the right place to get arduino-cli to see the fork of the platform?