support launching hostapd inside an interface block

[perkelix]

As mentioned during the discussion at #498, support for launching hostapd inside an interface block would be desirable.

The syntax could be as follow:

interface wlp3s1
hostapd /etc/hostapd/wlp3s1.conf
static ip_address=192.168.1.1/24

What dhcpcd would send out as a command line:

hostapd -B -P /run/hostapd.wlp3s1.pid /etc/hostapd/wlp3s1.conf

This would get us one step closer to deprecating ifupdown.

[rsmarples]

Why can't the OS's RC system do this? On NetBSD I would do this in /etc/rc.conf

# Start hostapd on the wlp3s1 interface
hostapd_flags="wlp3s1"
hostaps=YES

Anyway, right now you can do this in /etc/dhcpcd.enter-hook

if [ "$interface" = wlp3s1 ]; then
   case "$reason" in
   PREINIT) hostapd -B -P /run/hostapd.wlp3s1.pid /etc/hostapd/wlp3s1.conf;;
   STOP|STOP6) if [ -s /run/hostapd.wlp3s1.pid ]; then
      kill $(cat /run/hostapd.wlp3s1.pid)
      rm /run/hostapd.wlp3s1.pid
   fi;;
   esac
fi

But IMHO this is a bad idea as is trying to mange a VPN from dhcpcd as well. It's just the wrong place for this.

[perkelix]

Because if one needs to be able to launch several wireless devices as AP, each with its separate config, one won't go hacking DIY scripts.

[rsmarples]

You know hostapd supports many config files and thus many interfaces in one process right? Just like dhcpcd in manager mode.