This backports two fixes related to operation on DFS-required
channels.

When a DFS-required channel was selected as the regular
(non-outdoor-mode) 5 GHz channel, hostapd would switch to a non-DFS
channel as OpenWrt did not pass a chanlist of allowed ACS channels.

When hostapd is given a single channel for the chanlist or there's no
available channel left (all allowed channels are in the no-occupancy
period), hostapd prints "no DFS channels left, waiting for NOP to
finish" to the syslog but never stopped transmitting on this channel,
still sending out beacon frames and allowing client data transfer.

This adds the ability to cache OpenWrt dependencies on a per-target
base. Artifacts over 10MB are excluded, as GitHub imposes a limit of 5G
of available space per repository cache. This affects mostly
linux(-firmware) and gcc / gdb.

The goal is to reduce the total amount of requests necessary to fetch
dependencies.

(cherry picked from commit bf8c3bab)

Closes #1979
Closes #2062

(cherry picked from commit 582d2d69)

Document the behavior of the Outdoor mode when preserve_channels is
enabled.

This will hide the outdoor mode setting on compatible devices in case
the defined channels should be preserved.

Otherwise a user might be under the impression their device is compliant
with outdoor operation when in reality it still uses prohibited
channels.

Allow replacing the default OSM layer with a custom XYZ layer in
site.conf.

* build: target_config_lib: introduce concat_list helper

* build: rewrite features.sh in Lua

The `features` file is converted to a Lua-based DSL.

A helper function `_` is used in the DSL; this will return the original
string for enabled features, and nil for disabled features. This allows
to use boolean operations on features without making the code too
verbose.

Besides having more readable and robust code, this also fixes the bug
that all files `packages/*/features` were evaluated instead of only
using the feature definitions of currently active feeds.

* build: add luacheck support for package/features

The current manifest format was introduced with the new autoupdater in
Gluon v2018.1. Reduce the manifest size by 70% by removing the additional
manifest lines added for backwards compatiblity.

gluon-radv-filterd: minor cleanup

- #pragma once include guard
- include string.h to get memset and memcmp prototypes to fix respondd
  provider build warning

When the network connectivity is bad, routers may not appear in the
translation tables, or there may be no originator with TQ >0. Such
conditions to not warrant spamming the log with error messages.

The `features` file is converted to a Lua-based DSL.

A helper function `_` is used in the DSL; this will return the original
string for enabled features, and nil for disabled features. This allows
to use boolean operations on features without making the code too
verbose.

Besides having more readable and robust code, this also fixes the bug
that all files `packages/*/features` were evaluated instead of only
using the feature definitions of currently active feeds.

This commit changes the behavior for the wan-dnsmasq to read the
interfaces to update the DNS servers on from flag-files.

This way, external custom packages which add a custom VPN WAN interface
can update the DNS server gluon is using for WAN resolving.

b515edb775 ipq40xx: essedma: Disable TCP segmentation offload for IPv6
f7f15f8033 ath79: wndr3700 series: fix wifi range & throughput
1f5cbd6be7 ca-certificates: update to version 20200601
fa72f2646a oxnas: build with 8021Q VLAN support
e752fc1ff9 ath79: add support for TP-Link TL-WR802N V1 and V2
6488d2f7cc ath79: update WA/XC devices UBNT_VERSION to 8.5.3
fb79e5d9fe ipq806x: EA8500 fix boot partition detection
e36bdd5dc5 ath79: fix LEDs for GL.inet GL-AR150
21454a772b ar71xx: fix reset key for TP-Link TL-WR802N V1/V2
a32b0ec4cf generic: fix flow table hw offload

Closes #2055

When the GTK is offloaded, MT7610 won't transmit any multicast frames.
This is most likely due to a bug in the offloading datapath. MT7612 is
not affected.

Disable GTK offloading for now. It can be re-enabled once the bug in the
offloading path is fixed.

Signed-off-by: David Bauer <mail@david-bauer.net>

mac80211: rt2800: enable MFP support unconditionally

With very bad timing, it is possible that the teardown script of a
gluon_mesh interface runs when bat0 was just created, but primary0 is not
yet added to it. Although there is no hardif to remove in this case,
bat0 will still be deleted, because there is no hardif in bat0.

Disable the interface removal logic by passing `-M` to `batctl interface`.

v2020.2.x has been branched, so the current master is v2020.2+.

Enable 5GHz mesh interfaces when disabling outdoor mode, fix default status from site.conf

There is no setting to explicitly enable mesh interfaces in the config
wizard, so we need to enable mesh interfaces by default when the outdoor
mode is disabled (unless site.conf dictates otherwise).

The simplest way to achieve this is to delete the 5GHz mesh interface
sections when outdoor mode is disabled: 200-wireless would delete and
recreate them a moment later anyways, but by deleting them earlier we
ensure that the disabled status is initialized from site.conf again.

When disabling outdoor mode, 5GHz mesh interfaces should be enabled by
default again (unless disabled in site.conf).

Because is_disabled() was always returning true or false, the
first_non_nil() would never actually check the default setting from
site.conf. This was broken since v2017.1.

Fixes: 6cf03bab ("treewide: replace normal uses of luci.model.uci with simple-uci to reduce LuCI dependencies")

Normally, we build all nonshared packages (which includes all kernel
modules) to generate an opkg feed for later package installations by
users. On targets without opkg, this just wastes time - disable it.

Backporting the MFP patch allows us to utilize WPA3 features on this
target.

Tested on TP-Link Archer C20i

This gives us WPA3 support out of the box without having to manually disable
hardware crypto. The driver will fall back to software crypto if the connection
requires management frame protection.

THis allows us to use WPA3 features (Private-WiFi SAE & OWE) on
ramips-mt7620.

build: target_config_check: make check more lenient

Fix /etc/config/network commit for outdoor mode change, and related fixes

With 11a3b566 ("gluon-web-model: add dependency support for
sections"), a "reset" function was added to all model nodes. This
conflicts with the "reset" field of the Form object, making reset
buttons show labels like "function: 0xbb8d50" and possibly breaking form
processing when packages override the reset field.

The interfaces should always exist and just be disabled when outdoor
mode is enabled. Not creating them at all leads to an issue in the
advanced wifi settings where an additional reload of the page is
necessary after enabling or disabling the ourdoor mode to make the mesh
VIF options appear or disappear.

Instead of relying on the existence of interface sections only (which is
still used for the case of interface types that are not configured at
all in the site config), add a proper dependency.

This fixes section visiblity with enabled outdoor mode after the following
fix, and gives the user immediate feedback (allowing to disable outdoor
mode and enable meshing in a single step).

- Return early
- Rename to has_active_interfaces(), as it returns a boolean

200-wireless will add or remove the mesh network sections of
/etc/config/network. Commit this file, so the modified setting doesn't
get lost on reboot.

Fixes: #2048

Always allow options set to builtin (=y) when modular setting (=m) is
expected. This can happen when a package is added explicitly (in a
target defintion or site.mk) that is also pulled in as a dependency of
another builtin package.

Fixes: 9e23534e ("build: rework config generation")
Fixes: #2046

Validation errors are mostly handled in the frontend (by displaying
invalid fields with a red background). There was some code left in the
backend for handling different kinds of errors, and returning custom
error messages from validate(), but the resulting value was not used
anywhere.