This adds two new configuration options:
// The number of connections at which we stop trying to connect to more
// devices, zero meaning no limit. Does not affect incoming connections.
ConnectionLimitEnough int
// The maximum number of connections which we will allow in total, zero
// meaning no limit. Affects incoming connections and prevents
// attempting outgoing connections.
ConnectionLimitMax int
These can be used to limit the number of concurrent connections in
various ways.
This adds a statistic to track the last connection duration per device.
It isn't used for much in this PR, but it's available for #7223 to use
in deciding how to order device connection attempts (deprioritizing
devices that just dropped our connection the last time).
This breaks out some methods from the connection loop to make it simpler
to manage and understand.
Some slight simplifications to remove the `seen` variable (we can filter
`nextDial` based on times are in the future or not, so we don't need to
track `seen`) and adding a minimum loop interval (5s) in case some
dialer goes haywire and requests a 0s redial interval or such.
Otherwise no significant behavioral changes.
This does two things:
- Exclude QUIC from go1.16 builds, automatically, for now, since it
doesn't work and just panics.
- Provide some fake listeners and dialers when QUIC is disabled.
These fake listeners and dialers indicate that they are disabled and
unsupported, which silences "Dialing $address: unknown address scheme:
quic" type of stuff which is not super helpful to the user.
Our authentication is based on device ID (certificate fingerprint) but
we also check the certificate name for ... historical extra security
reasons. (I don't think this adds anything but it is what it is.) Since
that check breaks in Go 1.15 this change does two things:
- Adds a manual check for the peer certificate CommonName, and if they
are equal we are happy and don't call the more advanced
VerifyHostname() function. This allows our old style certificates to
still pass the check.
- Adds the cert name "syncthing" as a DNS SAN when generating the
certificate. This is the correct way nowadays and makes VerifyHostname()
happy in Go 1.15 as well, even without the above patch.
The QUIC package is notorious for being incompatible with either too
old or too new Go releases. Currently it doesn't build with Go 1.15 RC
and I want to test the rest with Go 1.15. With this I can do `go run
build.go --tags noquic` to do that.
- In the few places where we wrap errors, use the new Go 1.13 "%w"
construction instead of %s or %v.
- Where we create errors with constant strings, consistently use
errors.New and not fmt.Errorf.
- Remove capitalization from errors in the few places where we had that.
This splits large writes into smaller ones when using a rate limit,
making them into a legitimate trickle rather than large bursts with a
long time in between.
* lib/api, lib/connections, gui: Show connection error for disconnected devices (fixes#3345)
This adds functionality in the connetions service to track the last
error per address. That is in turn exposed in the /rest/system/status
API method, as that is also where we already show the listener status
from the connection service.
The GUI uses this info where it lists addresses, showing errors (if any)
in red underneath each address.
I also slightly refactored the existing status method on the connection
service to have a better name and return typed information.
* ok
* review
* formatting
* review
* lib/tlsutil: Enable TLS 1.3 when available, on test builds (fixes#5065)
This enables TLS 1.3 negotiation on Go 1.12 by setting the GODEBUG
variable. For now, this just gets enabled on test versions (those with a
dash in the version number).
Users wishing to enable this on production builds can set GODEBUG
manually.
The string representation of connections now includes the TLS version
and cipher suite. This becomes part of the log output on connections.
That is, when talking to an old client:
Established secure connection .../TLS1.2-TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
and now potentially:
Established secure connection .../TLS1.3-TLS_AES_128_GCM_SHA256
(The cipher suite was there previously in the log output, but not the
TLS version.)
I also added this info as a new Crypto() method on the connection, and
propagate this out to the API and GUI, where it can be seen in the
connection address hover (although with bad word wrapping sometimes).
* wip
* wip
