With Babel, wired meshing cannot run on the same logical interface as
non-mesh traffic, so using VXLAN is mandatory.

fastd: add L2TP offload support

treewide: Replace xhtml content type with html, remove xhtml workaround, replace self closing tags

The stdout output of gluon-web scripts is directly sent to uhttpd,
becoming a part of the HTML output or even replacing HTTP status or
headers. The output of gluon-reconfigure is not supposed to end up
there.

While we're at it, also add an exec to avoid an unnecessary shell
process.

The OpenLayers JS/CSS download URL is dead. Update it to make the map
work again:

- Update from OpenLayers 5.2.0 to 5.3.0
- Switch from the obsolete rawgit.com URL to jsdelivr.net (rawgit.com
  was only redirecting to jsdelivr.net for the last few years anyways)
- Set a fixed commit in the URL, so the URL doesn't become outdated again

Prevents spurious build failures.

- Restructure page
- Add information on how to add L2TPv3 offloading support to a build
  using configurable ciphers. The null method is not reocmmended anymore.
- Add notes and pointers regarding the gateway configuration to provide
  gateway admins with hints on how to modify their configuration to
  accommodate this new feature.
- Mention wireguard support

Based-on-patch-by: Felix Kaechele <felix@kaechele.ca>

THe "null" and "null@l2tp" methods are considered equivalent and always
added and removed together when the method list is "configurable".
"null@l2tp" is added before "null", so it is preferred when the peer
supports both.

This also drops the GMAC-based methods from gluon-mesh-vpn-fastd's
check_site.lua, as they are not supported anymore.

x86: copy separate kernel and rootfs images to "other" directory

gluon-web: prohibit cross-origin POST requests

Update OpenWrt base, clean up patches

lint-sh fixes

Removal of more obsolete migrations, minor cleanup and improvements to lsupgrade.sh

As gluon-web uses standard multipart/form-data requests, browsers don't
enforce any cross-origin restrictions. To prevent malicious injection of
POST requests into the config mode, match the Origin header against the
Host header of the request.

Actually raise an error and turn it into an HTTP 400 return code when
something goes wrong, rather than ignoring the error.

We also improve the conditions under which errors are thrown before
pump() is called: We don't need to check for the multipart/form-data
content-type twice, and a POST without this content-type is now always
an error.

Having a trailing newline is nice when viewing the returned data in a
terminal.

This was a remnant of LuCI that was never used in gluon-web.

Using apt in scripts is discouraged. Also add an update to hopefully fix
the lua-check installation failure in CI.

By applying a label `backport <branch>` the action will automatically
try to cherry-pick the change to the target branch after the pull
request was successfully merged.

Swap the interfaces so than the PoE input port LAN0 is used for WAN and
config mode, and LAN1 becomes LAN.

To this end, the code previously used for ar71xx and removed in
commit 9fdc57c1 ("treewide: drop ar71xx platform specific code") is
reintroduced.

Fixes #2384

/etc/config/gluon-core is used for nothing else.

As /etc/config/gluon uses a named wireless section, also change the
get_first() to get().

There wasn't really a reason to have a separate script to set a single
value.

In addition, the old script was using the identifier 'c' instead of
'uci' for the UCI cursor. Following the convention of the other scripts
is helpful so it is easy to grep for all uses of a certain config file/
option.

- Use printf instead of echo for better portability
- Print whole path without reordering components
- Deduplicate code

Iterating over all the package directories in the OpenWrt feed takes a
while, even though it doesn't contain any upgrade scripts. Skip the
whole directory.

We are on Linux 5.4, so these patches for Linux 4.14 don't do anything.

97b95ef8b918 uci: update to the latest master

Replace the downstream UCI patch with a proper OpenWrt 21.02 backport.

modules: updates