Currently `IsTraced("xyz")` will return true for
any inclusion of "xyz" in string.
This change splits `STTRACE` using `','`, `' '` and `';'`
as delimiters. That makes facilities separation
more clear.
This makes a couple of small improvements to the folder summary
mechanism:
- The folder summary includes the local and remote sequence numbers in
clear text, rather than some odd sum that I'm not sure what it was
intended to represent.
- The folder summary event is generated when appropriate, regardless of
whether there is an event listener. We did this before because
generating it was expensive, and we wanted to avoid doing it
unnecessarily. Nowadays, however, it's mostly just reading out
pre-calculated metadata, and anyway, it's nice if it shows up reliably
when running with -verbose.
The point of all this is to make it easier to use these events to judge
when devices are, in fact, in sync. As-is, if I'm looking at two
devices, it's very difficult to reliably determine if they are in sync
or not. The reason is that while we can ask device A if it thinks it's
in sync, we can't see if the answer is "yes" because it has processed
all changes from B, or if it just doesn't know about the changes from B
yet. With proper sequence numbers in the event we can compare the two
and determine the truth. This makes testing a lot easier.
This is a refactor of the protocol/model interface to take the actual
message as the parameter, instead of the broken-out fields:
```diff
type Model interface {
// An index was received from the peer device
- Index(conn Connection, folder string, files []FileInfo) error
+ Index(conn Connection, idx *Index) error
// An index update was received from the peer device
- IndexUpdate(conn Connection, folder string, files []FileInfo) error
+ IndexUpdate(conn Connection, idxUp *IndexUpdate) error
// A request was made by the peer device
- Request(conn Connection, folder, name string, blockNo, size int32, offset int64, hash []byte, weakHash uint32, fromTemporary bool) (RequestResponse, error)
+ Request(conn Connection, req *Request) (RequestResponse, error)
// A cluster configuration message was received
- ClusterConfig(conn Connection, config ClusterConfig) error
+ ClusterConfig(conn Connection, config *ClusterConfig) error
// The peer device closed the connection or an error occurred
Closed(conn Connection, err error)
// The peer device sent progress updates for the files it is currently downloading
- DownloadProgress(conn Connection, folder string, updates []FileDownloadProgressUpdate) error
+ DownloadProgress(conn Connection, p *DownloadProgress) error
}
```
(and changing the `ClusterConfig` to `*ClusterConfig` for symmetry;
we'll be forced to use all pointers everywhere at some point anyway...)
The reason for this is that I have another thing cooking which is a
small troubleshooting change to check index consistency during transfer.
This required adding a field or two to the index/indexupdate messages,
and plumbing the extra parameters in umpteen changes is almost as big a
diff as this is. I figured let's do it once and avoid having to do that
in the future again...
The rest of the diff falls out of the change above, much of it being in
test code where we run these methods manually...
This improves the ignore handling so that directories can be fully
ignored (skipped in the watcher) in more cases. Specifically, where the
previous rule was that any complex `!`-pattern would disable skipping
directories, the new rule is that only matches on patterns *after* such
a `!`-pattern disable skipping. That is, the following now does the
intuitive thing:
```
/foo
/bar
!whatever
*
```
- `/foo/**` and `/bar/**` are completely skipped, since there is no
chance anything underneath them could ever be not-ignored
- `!whatever` toggles the "can't skip directories any more" flag
- Anything that matches `*` can't skip directories, because it's
possible we can have `whatever` match something deeper.
To enable this, some refactoring was necessary:
- The "can skip dirs" flag is now a property of the match result, not of
the pattern set as a whole.
- That meant returning a boolean is not good enough, we need to actually
return the entire `Result` (or, like, two booleans but that seemed
uglier and more annoying to use)
- `ShouldIgnore(string) boolean` went away with
`Match(string).IsIgnored()` being the obvious replacement (API
simplification!)
- The watcher then needed to import the `ignore` package (for the
`Result` type), but `fs` imports the watcher and `ignore` imports `fs`.
That's a cycle, so I broke out `Result` into a package of its own so
that it can be safely imported everywhere in things like `type Matcher
interface { Match(string) result.Result }`. There's a fair amount of
stuttering in `result.Result` and maybe we should go with something like
`ignoreresult.R` or so, leaving this open for discussion.
Tests refactored to suit, I think this change is in fact quite well
covered by the existing ones...
Also some noise because a few of the changed files were quite old and
got the `gofumpt` treatment by my editor. Sorry not sorry.
---------
Co-authored-by: Simon Frei <freisim93@gmail.com>
### Purpose
Fix#9241 by expanding tildes in version paths.
When creating the versioner file system, first try to expand any leading
tildes to the user's home directory before handling relative paths. This
makes a version path `"~/p"` expand to `"$HOME/p"` instead of
`"/folder/~/p"`.
### Testing
Added a test to lib/versioner that exercises this code path. Also
manually tested with local syncthing instances.
### Purpose
This PR changes behaviour of syncthing related to `receive-only`
folders, which I believe to be a bug since I wouldn't expect the current
behaviour. With the current syncthing codebase, a file of a
`receive-only` folder that is only modified locally can cause the
creation of a `.sync-conflict` file.
### Testing
Consider this szenario: Setup two paired clients that sync a folder with
a given file (e.g. `Test.txt`). One of the clients configures the folder
to be `receive-only`. Now, change the contents of the file for the
receive-only client **_twice_**.
With the current syncthing codebase, this leads to the creation of a
`.sync-conflict` file that contains the modified contents, while the
regular `Test.txt` file is reset to the cluster's provided contents.
This is due to a `protocol.FileInfo#ShouldConflict` check, that is
succeeding on the locally modified file.
This PR changes this behaviour to not reset the file and not cause the
creation of a `.sync-conflict`. Instead, the second content update is
treated the same as the first content update.
This PR also contains a test that fails on the current codebase and
succeeds with the changes introduced in this PR.
### Screenshots
This is not a GUI change
### Documentation
This is not a user visible change.
## Authorship
Your name and email will be added automatically to the AUTHORS file
based on the commit metadata.
#### Thanks to all the syncthing folks for this awesome piece of
software!
This adds a "token manager" which handles storing and checking expired
tokens, used for both sessions and CSRF tokens. It removes the old,
corresponding functionality for CSRFs which saved things in a file. The
result is less crap in the state directory, and active login sessions
now survive a Syncthing restart (this really annoyed me).
It also adds a boolean on login to create a longer-lived session cookie,
which is now possible and useful. Thus we can remain logged in over
browser restarts, which was also annoying... :)
<img width="1001" alt="Screenshot 2023-12-12 at 09 56 34"
src="https://github.com/syncthing/syncthing/assets/125426/55cb20c8-78fc-453e-825d-655b94c8623b">
Best viewed with whitespace-insensitive diff, as a bunch of the auth
functions became methods instead of closures which changed indentation.
If syncOwnership is enabled and the remote uses for example a dockerized
Syncthing it can't fetch the ownername and groupname of the local
instance. Without this patch this led to an endless cycle of detected
changes on the remote and failing re-sync attempts.
This patch skips comparing the ownername and groupname if they zare empty
on one side.
See https://github.com/syncthing/syncthing/issues/9039 for details.
### Testing
Proposed by @calmh in
https://github.com/syncthing/syncthing/issues/9039#issuecomment-1870584783
and tested locally in my setup,
Setup PC 1:
- Syncthing is run in Docker as user `root` and has none of the users
configured that synchronize their files
Setup PC 2:
- this PC has all users locally setup
- Syncthing runs as `systemd` service as user `syncthing` and has
multiple capabilities set to set the correct owner and permissions
Setup PC 3:
- same as PC 2
Handling:
- `PC 1` is send & receive and uses just the `UID` and `GID` identifiers
to store the files
- `PC 2` and `PC 3` synchronize their files over `PC 1` but not directly
to each other
Outcome:
- `PC 2` and `PC 3` should send and receive their files with the correct
ownership and groups from `PC 1`
### Purpose
Instead of hardcoding `SigningKey` as text use `go:embed`. Fixes#9247.
### Testing
* Building syncthing
* Trying to upgrade (signature verification)
On kqueue-systems, folders listen for folder summaries to (be able to)
warn for potential high resource usage. However, it listened for any
folder summary and not for the summary which matches the folder it's
about. This could cause that an unwatched folder causes a folder summary
containing more files than the threshold (10k), and the listening folder
(with the watcher enabled) triggers the warning.
This makes sure that only the folder summaries which are relevant to the
specific folder are being handled.
### Testing
- Fire up some kqueue-system (freebsd, I used).
- add folder A, disable the watcher, add 10001 files
- add folder B with the watcher enabled, no files are needed here
Before the change:
- add an item to folder A, trigger a rescan to speed up the process
- wait some seconds...warning triggered by folder B's
summarySubscription
After the change:
- Only a warning is triggered if the received folder summary matches the
folder which listens for the summaries
Cleanup after #9275.
This renames `fmut` -> `mut`, removes the deadlock detector and
associated plumbing, renames some things from `...PRLocked` to
`...RLocked` and similar, and updates comments.
Apart from the removal of the deadlock detection machinery, no
functional code changes... i.e. almost 100% diff noise, have fun
reviewing.
I'm tired of the fmut/pmut shenanigans. This consolidates both under one
lock; I'm not convinced there are any significant performance
differences with this approach since we're literally just protecting map
juggling...
- The locking goes away when we were already under an appropriate fmut
lock.
- Where we had fmut.RLock()+pmut.Lock() it gets upgraded to an
fmut.Lock().
- Otherwise s/pmut/fmut/.
In order to avoid diff noise for an important change I did not do the
following cleanups, which will be filed in a PR after this one, if
accepted:
- Renaming fmut to just mut
- Renaming methods that refer to being "PRLocked" and stuff like that
- Removing the no longer relevant deadlock detector
- Comments referring to pmut and locking sequences...
This pull request allows syncthing to request an IPv6
[pinhole](https://en.wikipedia.org/wiki/Firewall_pinhole), addressing
issue #7406. This helps users who prefer to use IPv6 for hosting their
services or are forced to do so because of
[CGNAT](https://en.wikipedia.org/wiki/Carrier-grade_NAT). Otherwise,
such users would have to configure their firewall manually to allow
syncthing traffic to pass through while IPv4 users can use UPnP to take
care of network configuration already.
### Testing
I have tested this in a virtual machine setup with miniupnpd running on
the virtualized router. It successfully added an IPv6 pinhole when used
with IPv6 only, an IPv4 port mapping when used with IPv4 only and both
when dual-stack (IPv4 and IPv6) is used.
Automated tests could be added for SOAP responses from the router but
automatically testing this with a real network is likely infeasible.
### Documentation
https://docs.syncthing.net/users/firewall.html could be updated to
mention the fact that UPnP now works with IPv6, although this change is
more "behind the scenes".
---------
Co-authored-by: Simon Frei <freisim93@gmail.com>
Co-authored-by: bt90 <btom1990@googlemail.com>
Co-authored-by: André Colomb <github.com@andre.colomb.de>
Before introducing the service map and using it for folder runners, the
entries in folderCfgs and folderRunners for the same key/folder were
removed under a single lock. Stopping the folder happens separately
before that with just the read lock. Now with the service map stopping
the folder and removing it from the map is a single operation. And that
still happens with just a read-lock. However even with a full lock it’s
still problematic: After the folder stopped, the runner isn’t present
anymore while the folder-config still is and sais the folder isn't
paused.
The index handler in turn looks at the folder config that is not paused,
thus assumes the runner has to be present -> nil deref on the runner.
A better solution might be to push most of these fmut maps into the
folder - they anyway are needed in there. Then there's just a single
map/source of info that's necessarily consistent. That's quite a bit of
work though, and probably/likely there will be corner cases there too.
This reduces allocations, in number and in size, while getting extended
attributes. This is mostly noticable when there is a large number of new
files to scan and we're running with the default scanProgressInterval --
then a queue of files is built in-memory, and this queue includes
extended attributes as part of file metadata. (Arguable it shouldn't,
but that's a more difficult and involved change.)
With 1M files to scan, each with one extended attribute, current peak
memory usage looks like this:
Showing nodes accounting for 1425.30MB, 98.19% of 1451.64MB total
Dropped 1435 nodes (cum <= 7.26MB)
Showing top 10 nodes out of 54
flat flat% sum% cum cum%
976.56MB 67.27% 67.27% 976.56MB 67.27%
github.com/syncthing/syncthing/lib/fs.getXattr
305.44MB 21.04% 88.31% 305.44MB 21.04%
github.com/syncthing/syncthing/lib/scanner.(*walker).walk.func1
45.78MB 3.15% 91.47% 1045.23MB 72.00%
github.com/syncthing/syncthing/lib/fs.(*BasicFilesystem).GetXattr
22.89MB 1.58% 93.04% 22.89MB 1.58%
github.com/syncthing/syncthing/lib/fs.listXattr
22.89MB 1.58% 94.62% 22.89MB 1.58%
github.com/syncthing/syncthing/lib/protocol.(*PlatformData).SetXattrs
16MB 1.10% 95.72% 16.01MB 1.10%
github.com/syndtr/goleveldb/leveldb/memdb.New
After the change, it's this:
Showing nodes accounting for 502.32MB, 95.70% of 524.88MB total
Dropped 1400 nodes (cum <= 2.62MB)
Showing top 10 nodes out of 91
flat flat% sum% cum cum%
305.43MB 58.19% 58.19% 305.43MB 58.19%
github.com/syncthing/syncthing/lib/scanner.(*walker).walk.func1
45.79MB 8.72% 66.91% 68.68MB 13.09%
github.com/syncthing/syncthing/lib/fs.(*BasicFilesystem).GetXattr
32MB 6.10% 73.01% 32.01MB 6.10%
github.com/syndtr/goleveldb/leveldb/memdb.New
22.89MB 4.36% 77.37% 22.89MB 4.36%
github.com/syncthing/syncthing/lib/fs.listXattr
22.89MB 4.36% 81.73% 22.89MB 4.36%
github.com/syncthing/syncthing/lib/protocol.(*PlatformData).SetXattrs
15.35MB 2.92% 84.66% 15.36MB 2.93%
github.com/syndtr/goleveldb/leveldb/util.(*BufferPool).Get
15.28MB 2.91% 87.57% 15.28MB 2.91% strings.(*Builder).grow
(The usage for xattrs is reduced from 976 MB to 68 MB)
LastSeen for a device was only updated when they connected. This now
updates it when they disconnect, so that we remember the last time we
actually saw them. When asking the API for current stats, currently
connected devices get a last seen value of the current time.
This adds our short device ID to the basic auth realm. This has at least
two consequences:
- It is different from what's presented by another device on the same
address (e.g., if I use SSH forwards to different dives on the same
local address), preventing credentials for one from being sent to
another.
- It is different from what we did previously, meaning we avoid cached
credentials from old versions interfering with the new login flow.
I don't *think* there should be things that depend on our precise realm
string, so this shouldn't break any existing setups...
Sneakily this also changes the session cookie and CSRF name, because I
think `id.Short().String()` is nicer than `id.String()[:5]` and the
short ID is two characters longer. That's also not a problem...
This makes the new default $XDG_STATE_HOME/syncthing or
~/.local/state/syncthing, while still looking in legacy locations first
for existing installs.
Note that this does not *move* existing installs, and nor should we.
Existing paths will continue to be used as-is, but the user can move the
dir into the new place if they want to use it (as they could prior to
this change as well, for that matter).
### Documentation
Needs update to the config docs about our default locations.
lib/fs: Fix conflicts on Android due to fluctuating inode change time
[1] added inode change time to file info in order to support syncing
extended attributes. However, in the case of Android, this inode change
time fluctuates, leading to unexpected conflicts even when the user has
not even touched the files on the Android device itself. Thus, in order
to prevent those conflicts from happening, do not write inode change
time on Android.
[1] 6cac308bcd
Signed-off-by: Tomasz Wilczyński <twilczynski@naver.com>
### Purpose
Deduplicated files are apparently considered 'irregular' under the hood,
this causes them to simply be ignored by Syncthing. This change is more
of a workaround than a proper fix, as the fix should probably happen in
the underlying libraries? - which may take some time. In the meanwhile,
this change should make deduplicated files be treated as regular files
and be indexed and synced as they should.
### Testing
Create some volume where deduplication is turned on (see the relevant
issue for details, including a proper description of how to reproduce
it). Prior to this change, the deduplicated files were simply ignored
(even by the indexer). After this change, the deduplicated files are
being index and synced properly.
This is motivated by the Android app:
https://github.com/syncthing/syncthing-android/pull/1982#issuecomment-1752042554
The planned fix in response to basic auth behaviour changing in #8757
was to add the `Authorization` header when opening the WebView, but it
turns out the function used only applies the header to the initial page
load, not any subsequent script loads or AJAX calls. The
`basicAuthAndSessionMiddleware` checks for no-auth exceptions before
checking the `Authorization` header, so the header has no effect on the
initial page load since the `/` path is a no-auth exception. Thus the
Android app fails to log in when opening the WebView.
This changes the order of checks in `basicAuthAndSessionMiddleware` so
that the `Authorization` header is always checked if present, and a
session cookie is set if it is valid. Only after that does the
middleware fall back to checking for no-auth exceptions.
`api_test.go` has been expanded with additional checks:
- Check that a session cookie is set whenever correct basic auth is
provided.
- Check that a session cookie is not set when basic auth is incorrect.
- Check that a session cookie is not set when authenticating with an API
token (either via `X-Api-Key` or `Authorization: Bearer`).
And an additional test case:
- Check that requests to `/` always succeed, but receive a session
cookie when correct basic auth is provided.
I have manually verified that
- The new assertions fail if the `createSession` call is removed in
`basicAuthAndSessionMiddleware`.
- The new test cases in e6e4df4d7034302b729ada6d91cff6e2b29678da fail
before the change in 0e47d37e738d4c15736c496e01cd949afb372e71 is
applied.
improve parsing of gui-address overrides
make checks for whether the gui-address is overridden consistent by
checking whether the environment variable is set and not an empty
string. the `Network()` function however checked for the inclusion of
a slash instead of the presence of any characters. If the config file's
gui address was set to a unix socket and the gui override to a tcp
address, then the function would have wrongly returned "unix".
the `URL()` function always returned the config file's gui address if a
unix socket was configured, even if an override was specified.
the `URL()` function wrongly formatted unix addresses. the http(s)
protocol was used as the sheme and the path was percent escaped. because
of the previous bug, this could only be triggered if the config file's
gui address was tcp and an unix socket override was given.
simplify the `useTLS()` function's codepath for overrides.
Co-authored-by: digital <didev@dinid.net>
I don't really understand under what circumstances, but sometimes these
calls panic with a "panic: counter cannot decrease in value" because the
value passed to Add() was negative.
In principle a connection can close while it's in progress with
starting, and then it's undefined if we wait for goroutines to exit etc.
With this change, we will wait for start to complete before starting to
stop everything.
This adds the ability to have multiple concurrent connections to a single device. This is primarily useful when the network has multiple physical links for aggregated bandwidth. A single connection will never see a higher rate than a single link can give, but multiple connections are load-balanced over multiple links.
It is also incidentally useful for older multi-core CPUs, where bandwidth could be limited by the TLS performance of a single CPU core -- using multiple connections achieves concurrency in the required crypto calculations...
Co-authored-by: Simon Frei <freisim93@gmail.com>
Co-authored-by: tomasz1986 <twilczynski@naver.com>
Co-authored-by: bt90 <btom1990@googlemail.com>
Instead of separately tracking the token.
Also changes serviceMap to have a channel version of RemoveAndWait, so
that it's possible to do the removal under a lock but wait outside of
the lock. And changed where we do that in connection close, reversing
the change that happened when I added the serviceMap in 40b3b9ad1.
By creating the http.Transport and tls.Configuration ourselves we
override some default behavior and end up with a client that speaks only
HTTP/1.1.
This adds a call to http.ConfigureTransport to do the relevant magic to
enable HTTP/2.
Also tweaks the keepalive settings to be a little kinder to the
server(s).
The allowed IPv4 ranges are the same as before. But we now also accept IPv6 addresses in the ULA range FC00::/7. These addresses don't require an interface identifier and are roughly equivalent to the IPv4 private ranges.
Typical usecases:
VPN interface IPs: Wireguard, OpenVPN, Tailscale, ...
fixed IPv6 LAN addressing while the provider assigns a dynamic prefix. e.g used by pihole
https://cs.opensource.google/go/go/+/refs/tags/go1.21.0:src/net/ip.go;l=146
* lib/versioner: Factor out DefaultPath constant.
Replace several instances where .stversions is named literally to all
use the same definition in the versioner package. Exceptions are the
packages where a cyclic dependency on versioner is impossible, or some
tests which combine the versions base path with other components.
* lib/versioner: Fix comment about trash can in simple versioner.
* lib/versioner: Fix wrong versioning type string in error message.
The error message shows the folder type instead of the versioning
type, although the correct field is used in the comparison.
Safety check added in v1.23.6 introduced bug. Bug unshares folders with untrusted devices if folder does not have an encryption password set, regardless of whether the folder is shared with the untrusted device as encrypted or not. Prevents sharing with untrusted devices in some cases where sharing would be encrypted.
Patch preserves safety check but permits sharing folders with untrusted devices if they are shared as encrypted.
Signed-off-by: kewiha <keithh@protonmail.com>
Currently, historically, we look for the `X-API-Key` header to
authenticate with an API key. There's nothing wrong with this, but in
some scenarios it's easier to produce an `Authorization` header with a
`Bearer $token` content, which is nowadays more common. This change adds
support for both, so that we will accept an API key either in our custom
header or as a bearer token.
Currently, because of devices with unset RTC clock, the 100% percentile
for Uptime on [1] is calculated since the Unix epoch which is useless as
far as usage statistics are concerned. Thus, if the Syncthing start time
is set to a past date, assume that the clock is wrong and do not even
try to report the uptime.
[1] https://data.syncthing.net
Signed-off-by: Tomasz Wilczyński <twilczynski@naver.com>
Co-authored-by: Jakob Borg <jakob@kastelo.net>
refactor: replace empty slice literal with `var`
An empty slice can be represented by `nil` or an empty slice literal. They are
functionally equivalent — their `len` and `cap` are both zero — but the `nil`
slice is the preferred style. For more information about empty slices,
see [Declaring Empty Slices](https://github.com/golang/go/wiki/CodeReviewComments#declaring-empty-slices).
Co-authored-by: deepsource-autofix[bot] <62050782+deepsource-autofix[bot]@users.noreply.github.com>
refactor: fix unused method receiver
Methods with unused receivers can be a symptom of unfinished refactoring or a bug. To keep
the same method signature, omit the receiver name or '_' as it is unused.
Co-authored-by: deepsource-autofix[bot] <62050782+deepsource-autofix[bot]@users.noreply.github.com>
refactor: unused parameter should be replaced by underscore
Unused parameters in functions or methods should be replaced with `_`
(underscore) or removed.
Co-authored-by: deepsource-autofix[bot] <62050782+deepsource-autofix[bot]@users.noreply.github.com>
This adds an environment variable STVERSIONEXTRA that, when set, gets
added to the version information in the API and GUI.
The purpose of all this is to be able to communicate something about the
bundling or packaging, through the log & GUI and the end user, to the
potential person supporting it -- i.e., us. :) A wrapper can set this
variable to indicate that Syncthing is being run via `SyncTrayzor`,
`Syncthing-macOS`, etc., and thus indicate to the end user that the GUI
they are looking at is perhaps not the only source of truth and
management for this instance.
With this change, error messages include the offending characters or
name parts. Examples:
nul.txt: name is invalid, contains Windows reserved name: "nul"
foo>bar.txt: name is invalid, contains Windows reserved character: ">"
foo \bar.txt: name is invalid, must not end in space or period on Windows
This prevents combining untrusted with introducer and auto-accept, and
also verifies that folders shared with untrusted devices have passwords
at config loading time.
Co-authored-by: Simon Frei <freisim93@gmail.com>
We usually want to ensure that our own device is present. However if the
given device ID is the empty ID, we shouldn't do that. This is a
legimate (though way too non-obvious) use-case when opening the config
without knowing/caring about the device ID.
* Platform data (ownership, xattrs, etc.) is now set correctly for newly-received folders, even if the received folder has the NoPermissions flag.
* Call setPlatformData on receivers that have ignorePerms set to true.
This fixes various test issues with Go 1.20.
- Most tests rewritten to use fakefs where possible
- Some tests that were already skipped, or dubious (invasive,
unmaintainable, unclear what they even tested) have been removed
- Some actual code rewritten to better support testing in fakefs
Co-authored-by: Eric P <eric@kastelo.net>
In the sequence of loading ignores, the error File Does Not Exist is not being considered a fatal error, since the .stignore file is allowed to not exist. However, included ignore files also tossed that same error in case those do not exist while in those cases it's considered an error and it should lead to the folder stopping. Changing the error when opening an included ignore file to something other than the regular does fix this issue, as in it now works again as described in the Documentation.
This makes the various protocol priorities configurable among the other
options. With this, it's possible to prefer QUIC over TCP for WAN
connections, for example. Both sides need to be similarly configured for
this to work properly.
The default priority order remains the same as previously (TCP, QUIC,
Relay, with LAN better than WAN).
To make this happen I made each dialer & listener more priority aware,
and moved the check for whether a connection is LAN or not into the
dialer / listener -- this is the new "lanChecker" type that's passed
around.
