luci-mod-admin-full: figure out diagnostics host in postinstall

Attempt to infer the default diagnostics host for nslookup / ping / traceroute
from the various URLs in /etc/os-release. Fall back to "openwrt.org" if no
host is found to preserve backwards compatibility.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

modules/luci-mod-admin-full/root/etc/uci-defaults/50_luci-mod-admin-full

@@ -0,0 +1,22 @@
+#!/bin/sh
+
+if [ "$(uci -q get luci.diag)" != "internal" ]; then
+	host=""
+
+	if [ -s /etc/os-release ]; then
+		. /etc/os-release
+		host="${HOME_URL:-${BUG_URL:-$LEDE_DEVICE_MANUFACTURER_URL}}"
+		host="${host#*://}"
+		host="${host%%/*}"
+	fi
+
+	uci -q batch <<-EOF >/dev/null
+		set luci.diag=internal
+		set luci.diag.dns='${host:-openwrt.org}'
+		set luci.diag.ping='${host:-openwrt.org}'
+		set luci.diag.route='${host:-openwrt.org}'
+		commit luci
+	EOF
+fi
+
+exit 0