Prepare for path MTU discovery by splitting up the concept of
DefaultMTU() into the concepts of the Tailscale TUN MTU, MTUs of
underlying network interfaces, minimum "safe" TUN MTU, user configured
TUN MTU, probed path MTU to a peer, and maximum probed MTU. Add a set
of likely MTUs to probe.
Updates #311
Signed-off-by: Val <valerie@tailscale.com>
Replace CanPMTUD() with ShouldPMTUD() to check if peer path MTU discovery should
be enabled, in preparation for adding support for enabling/disabling peer MTU
dynamically.
Updated #311
Signed-off-by: Val <valerie@tailscale.com>
Add an enable/disable argument to setDontFragment() in preparation for dynamic
enable/disable of peer path MTU discovery. Add getDontFragment() to get the
status of the don't fragment bit from a socket.
Updates #311
Co-authored-by: James Tucker <james@tailscale.com>
Signed-off-by: Val <valerie@tailscale.com>
Use IPV6_MTU_DISCOVER for setting don't fragment on IPv6 sockets on Linux (was
using IP_MTU_DISCOVER, the IPv4 arg).
Updates #311
Signed-off-by: Val <valerie@tailscale.com>
Make the debugknob variable name for enabling peer path MTU discovery match the
env variable name.
Updates #311
Signed-off-by: Val <valerie@tailscale.com>
And convert all callers over to the methods that check SelfNode.
Now we don't have multiple ways to express things in tests (setting
fields on SelfNode vs NetworkMap, sometimes inconsistently) and don't
have multiple ways to check those two fields (often only checking one
or the other).
Updates #9443
Change-Id: I2d7ba1cf6556142d219fae2be6f484f528756e3c
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
NetworkMap.Addresses is redundant with the SelfNode.Addresses. This
works towards a TODO to delete NetworkMap.Addresses and replace it
with a method.
This is similar to #9389.
Updates #cleanup
Change-Id: Id000509ca5d16bb636401763d41bdb5f38513ba0
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
LocalBackend can talk to magicsock on its own to do this without
the "Engine" being involved.
(Continuing a little side quest of cleaning up the Engine
interface...)
Updates #cleanup
Change-Id: I8654acdca2b883b1bd557fdc0cfb90cd3a418a62
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Currently only the top four most popular changes: endpoints, DERP
home, online, and LastSeen.
Updates #1909
Change-Id: I03152da176b2b95232b56acabfb55dcdfaa16b79
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
We're trying to start using that monster type less and eventually get
rid of it.
Updates #1909
Change-Id: I8e1e725bce5324fb820a9be6c7952767863e6542
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This is both more efficient (because the knobs' bool is only updated
whenever Node is changed, rarely) and also gets us one step closer to
removing a case of storing a netmap.NetworkMap in
magicsock. (eventually we want to phase out much of the use of that
type internally)
Updates #1909
Change-Id: I37e81789f94133175064fdc09984e4f3a431f1a1
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Previously two tsnet nodes in the same process couldn't have disjoint
sets of controlknob settings from control as both would overwrite each
other's global variables.
This plumbs a new controlknobs.Knobs type around everywhere and hangs
the knobs sent by control on that instead.
Updates #9351
Change-Id: I75338646d36813ed971b4ffad6f9a8b41ec91560
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
In prep for incremental netmap update plumbing (#1909), make peerMap
also keyed by NodeID, as all the netmap node mutations passed around
later will be keyed by NodeID.
In the process, also:
* add envknob.InDevMode, as a signal that we can panic more aggressively
in unexpected cases.
* pull two moderately large blocks of code in Conn.SetNetworkMap out
into their own methods
* convert a few more sets from maps to set.Set
Updates #1909
Change-Id: I7acdd64452ba58e9d554140ee7a8760f9043f961
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
I didn't clean up the more idiomatic map[T]bool with true values, at
least yet. I just converted the relatively awkward struct{}-valued
maps.
Updates #cleanup
Change-Id: I758abebd2bb1f64bc7a9d0f25c32298f4679c14f
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Replace %w verb with %v verb when logging errors.
Use %w only for wrapping errors with fmt.Errorf()
Fixes: #9213
Signed-off-by: Craig Rodrigues <rodrigc@crodrigues.org>
I'm not saying it works, but it compiles.
Updates #5794
Change-Id: I2f3c99732e67fe57a05edb25b758d083417f083e
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Upcoming work on incremental netmap change handling will require some
replumbing of which subsystems get notified about what. Done naively,
it could break "tailscale status --json" visibility later. To make sure
I understood the flow of all the updates I was rereading the status code
and realized parts of ipnstate.Status were being populated by the wrong
subsystems.
The engine (wireguard) and magicsock (data plane, NAT traveral) should
only populate the stuff that they uniquely know. The WireGuard bits
were fine but magicsock was populating stuff stuff that LocalBackend
could've better handled, so move it there.
Updates #1909
Change-Id: I6d1b95d19a2d1b70fbb3c875fac8ea1e169e8cb0
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
If we don't have the ICMP hint available, such as on Android, we can use
the signal of rx traffic to bias toward a particular endpoint.
We don't want to stick to a particular endpoint for a very long time
without any signals, so the sticky time is reduced to 1 second, which is
large enough to avoid excessive packet reordering in the common case,
but should be small enough that either rx provides a strong signal, or
we rotate in a user-interactive schedule to another endpoint, improving
the feel of failover to other endpoints.
Updates #8999
Co-authored-by: Charlotte Brandhorst-Satzkorn <charlotte@tailscale.com>
Signed-off-by: James Tucker <james@tailscale.com>
Signed-off-by: Charlotte Brandhorst-Satzkorn <charlotte@tailscale.com>
There are cases where we do not detect the non-viability of a route, but
we will instead observe a failure to send. In a Disco path this would
normally be handled as a side effect of Disco, which is not available to
non-Disco WireGuard nodes. In both cases, recognizing the failure as
such will result in faster convergence.
Updates #8999
Signed-off-by: James Tucker <james@tailscale.com>
LastFullPing is now used for disco or wireguard only endpoints. This
change updates the comment to make that clear.
Updates #7826
Signed-off-by: Charlotte Brandhorst-Satzkorn <charlotte@tailscale.com>
There are latency values stored in bestAddr and endpointState that are
no longer applicable after a connectivity change and should be cleared
out, following the documented behavior of the function.
Updates #8999
Signed-off-by: James Tucker <james@tailscale.com>
When sending a ping from the CLI, only accept a pong that is in reply
to the specific CLI ping we sent.
Updates #311
Signed-off-by: Val <valerie@tailscale.com>
Now a nodeAttr: ForceBackgroundSTUN, DERPRoute, TrimWGConfig,
DisableSubnetsIfPAC, DisableUPnP.
Kept support for, but also now a NodeAttr: RandomizeClientPort.
Removed: SetForceBackgroundSTUN, SetRandomizeClientPort (both never
used, sadly... never got around to them. But nodeAttrs are better
anyway), EnableSilentDisco (will be a nodeAttr later when that effort
resumes).
Updates #8923
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
To record wether user is using iptables or nftables after we add support to nftables on linux, we
are adding a field FirewallMode to NetInfo in HostInfo to reflect what firewall mode the host is
running, and form metrics. The information is gained from a global constant in hostinfo.go. We
set it when selection heuristic made the decision, and magicsock reports this to control.
Updates: tailscale/corp#13943
Signed-off-by: KevinLiang10 <kevinliang@tailscale.com>
If a node is flapping or otherwise generating lots of STUN endpoints, we
can end up caching a ton of useless values and sending them to peers.
Instead, let's apply a fixed per-Addr limit of endpoints that we cache,
so that we're only sending peers up to the N most recent.
Updates tailscale/corp#13890
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I8079a05b44220c46da55016c0e5fc96dd2135ef8
Netcheck no longer performs I/O itself, instead it makes requests via
SendPacket and expects users to route reply traffic to
ReceiveSTUNPacket.
Netcheck gains a Standalone function that stands up sockets and
goroutines to implement I/O when used in a standalone fashion.
Magicsock now unconditionally routes STUN traffic to the netcheck.Client
that it hosts, and plumbs the send packet sink.
The CLI is updated to make use of the Standalone mode.
Fixes#8723
Signed-off-by: James Tucker <james@tailscale.com>
This sets the Don't Fragment flag, for now behind the
TS_DEBUG_ENABLE_PMTUD envknob.
Updates #311.
Signed-off-by: Val <valerie@tailscale.com>
Signed-off-by: salman <salman@tailscale.com>
This adds the capability to pad disco ping message payloads to reach a
specified size. It also plumbs it through to the tailscale ping -size
flag.
Disco pings used for actual endpoint discovery do not use this yet.
Updates #311.
Signed-off-by: salman <salman@tailscale.com>
Co-authored-by: Val <valerie@tailscale.com>
The nonce value is not read by anything, and di.sharedKey.Seal()
a few lines below generates its own. #cleanup
Signed-off-by: salman <salman@tailscale.com>
This change removes the noV4/noV6 check from addrForSendWireGuardLocked.
On Android, the client panics when reaching `rand.Intn()`, likely due to
the candidates list being containing no candidates. The suspicion is
that the `noV4` and the `noV6` are both being triggered causing the
loop to continue.
Updates tailscale/corp#12938
Updates #7826
Signed-off-by: Charlotte Brandhorst-Satzkorn <charlotte@tailscale.com>
Switch our best address selection to use a scoring-based approach, where
we boost each address based on whether it's a private IP or IPv6.
For users in cloud environments, this biases endpoint selection towards
using an endpoint that is less likely to cost the user money, and should
be less surprising to users.
This also involves updating the tests to not use private IPv4 addresses;
other than that change, the behaviour should be identical for existing
endpoints.
Updates #8097
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I069e3b399daea28be66b81f7e44fc27b2943d8af
This change introduces address selection for wireguard only endpoints.
If a endpoint has not been used before, an address is randomly selected
to be used based on information we know about, such as if they are able
to use IPv4 or IPv6. When an address is initially selected, we also
initiate a new ICMP ping to the endpoints addresses to determine which
endpoint offers the best latency. This information is then used to
update which endpoint we should be using based on the best possible
route. If the latency is the same for a IPv4 and an IPv6 address, IPv6
will be used.
Updates #7826
Signed-off-by: Charlotte Brandhorst-Satzkorn <charlotte@tailscale.com>
Avoid selecting an endpoint as "better" than the current endpoint if the
total latency improvement is less than 1%. This adds some hysteresis to
avoid flapping between endpoints for a minimal improvement in latency.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: If8312e1768ea65c4b4d4e13d8de284b3825d7a73
On some platforms (notably macOS and iOS) we look up the default
interface to bind outgoing connections to. This is both duplicated
work and results in logspam when the default interface is not available
(i.e. when a phone has no connectivity, we log an error and thus cause
more things that we will try to upload and fail).
Fixed by passing around a netmon.Monitor to more places, so that we can
use its cached interface state.
Fixes#7850
Updates #7621
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
We're using it in more and more places, and it's not really specific to
our use of Wireguard (and does more just link/interface monitoring).
Also removes the separate interface we had for it in sockstats -- it's
a small enough package (we already pull in all of its dependencies
via other paths) that it's not worth the extra complexity.
Updates #7621
Updates #7850
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
This is a follow-up to #7905 that adds two more linters and fixes the corresponding findings. As per the previous PR, this only flags things that are "obviously" wrong, and fixes the issues found.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I8739bdb7bc4f75666a7385a7a26d56ec13741b7c
Previously, when updating endpoints we would immediately stop
advertising any endpoint that wasn't discovered during
determineEndpoints. This could result in, for example, a case where we
performed an incremental netcheck, didn't get any of our three STUN
packets back, and then dropped our STUN endpoint from the set of
advertised endpoints... which would result in clients falling back to a
DERP connection until the next call to determineEndpoints.
Instead, let's cache endpoints that we've discovered and continue
reporting them to clients until a timeout expires. In the above case
where we temporarily don't have a discovered STUN endpoint, we would
continue reporting the old value, then re-discover the STUN endpoint
again and continue reporting it as normal, so clients never see a
withdrawal.
Updates tailscale/coral#108
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I42de72e7418ab328a6c732bdefc74549708cf8b9
The comment still said *magicsock.Conn implemented wireguard-go conn.Bind.
That wasn't accurate anymore.
A doc #cleanup.
Change-Id: I7fd003b939497889cc81147bfb937b93e4f6865c
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
So we're staying within the netip.Addr/AddrPort consistently and
avoiding allocs/conversions to the legacy net addr types.
Updates #5162
Change-Id: I59feba60d3de39f773e68292d759766bac98c917
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
These tests are passing locally and on CI. They had failed earlier in
the day when first fixing up CI, and it is not immediately clear why. I
have cycled IPv6 support locally, but this should not have a substantial
effect.
Updates #7876
Signed-off-by: James Tucker <jftucker@gmail.com>
We accidentally switched to ./tool/go in
4022796484 which resulted in no longer
running Windows builds, as this is attempting to run a bash script.
I was unable to quickly fix the various tests that have regressed, so
instead I've added skips referencing #7876, which we need to back and
fix.
Updates #7262
Updates #7876
Signed-off-by: James Tucker <james@tailscale.com>
This also adds a bunch of tests for this function to ensure that we're
returning the proper IP(s) in all cases.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I0d9d57170dbab5f2bf07abdf78ecd17e0e635399
This makes `omitempty` actually work, and saves bytes in each map response.
Updates tailscale/corp#8020
Signed-off-by: Maisem Ali <maisem@tailscale.com>
Using log.Printf may end up being printed out to the console, which
is not desirable. I noticed this when I was investigating some client
logs with `sockstats: trace "NetcheckClient" was overwritten by another`.
That turns to be harmless/expected (the netcheck client will fall back
to the DERP client in some cases, which does its own sockstats trace).
However, the log output could be visible to users if running the
`tailscale netcheck` CLI command, which would be needlessly confusing.
Updates tailscale/corp#9230
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
The lazy initialization of the disco key is not necessary, and
contributes to unnecessary locking and state checking.
Updates #cleanup
Signed-off-by: James Tucker <james@tailscale.com>
A peer can have IsWireGuardOnly, which means it will not support DERP or
Disco, and it must have Endpoints filled in order to be usable.
In the present implementation only the first Endpoint will be used as
the bestAddr.
Updates tailscale/corp#10351
Co-authored-by: Charlotte Brandhorst-Satzkorn <charlotte@tailscale.com>
Co-authored-by: James Tucker <james@tailscale.com>
Signed-off-by: James Tucker <james@tailscale.com>
Identified in review in #7821 endpoint.discoKey and endpoint.discoShort
are often accessed without first taking endpoint.mu. The arrangement
with endpoint.mu is inconvenient for a good number of those call-sites,
so it is instead replaced with an atomic pointer to carry both pieces of
disco info. This will also help with #7821 that wants to add explicit
checks/guards to disable disco behaviors when disco keys are missing
which is necessarily implicitly mostly covered by this change.
Updates #7821
Signed-off-by: James Tucker <james@tailscale.com>
Make developing derp easier by:
1. Creating an envknob telling clients to use HTTP to connect to derp
servers, so devs don't have to acquire a valid TLS cert.
2. Creating an envknob telling clients which derp server to connect
to, so devs don't have to edit the ACLs in the admin console to add a
custom DERP map.
3. Explaining how the -dev and -a command lines args to derper
interact.
To use this:
1. Run derper with -dev.
2. Run tailscaled with TS_DEBUG_USE_DERP_HTTP=1 and
TS_DEBUG_USE_DERP_ADDR=localhost
This will result in the client connecting to derp via HTTP on port
3340.
Fixes#7700
Signed-off-by: Val <valerie@tailscale.com>
This commit implements UDP offloading for Linux. GSO size is passed to
and from the kernel via socket control messages. Support is probed at
runtime.
UDP GSO is dependent on checksum offload support on the egress netdev.
UDP GSO will be disabled in the event sendmmsg() returns EIO, which is
a strong signal that the egress netdev does not support checksum
offload.
Updates tailscale/corp#8734
Signed-off-by: Jordan Whited <jordan@tailscale.com>
This adds the util/sysresources package, which currently only contains a
function to return the total memory size of the current system.
Then, we modify magicsock to scale the number of buffered DERP messages
based on the system's available memory, ensuring that we never use a
value lower than the previous constant of 32.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ib763c877de4d0d4ee88869078e7d512f6a3a148d
This commit updates the wireguard-go dependency to pull in fixes for
the tun package, specifically 052af4a and aad7fca.
Signed-off-by: Jordan Whited <jordan@tailscale.com>
* wgengine/magicsock: add envknob to send CallMeMaybe to non-existent peer
For testing older client version responses to the PeerGone packet format change.
Updates #4326
Signed-off-by: Val <valerie@tailscale.com>
* derp: remove dead sclient struct member replaceLimiter
Leftover from an previous solution to the duplicate client problem.
Updates #2751
Signed-off-by: Val <valerie@tailscale.com>
* derp, derp/derphttp, wgengine/magicsock: add new PeerGone message type Not Here
Extend the PeerGone message type by adding a reason byte. Send a
PeerGone "Not Here" message when an endpoint sends a disco message to
a peer that this server has no record of.
Fixes#4326
Signed-off-by: Val <valerie@tailscale.com>
---------
Signed-off-by: Val <valerie@tailscale.com>
This change adds a ringbuffer to each magicsock endpoint that keeps a
fixed set of "changes"–debug information about what updates have been
made to that endpoint.
Additionally, this adds a LocalAPI endpoint and associated
"debug peer-status" CLI subcommand to fetch the set of changes for a given
IP or hostname.
Updates tailscale/corp#9364
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I34f726a71bddd0dfa36ec05ebafffb24f6e0516a
Makes it cheaper/simpler to persist values, and encourages reuse of
labels as opposed to generating an arbitrary number.
Updates tailscale/corp#9230
Updates #3363
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
The debug flag on tailscaled isn't available in the macOS App Store
build, since we don't have a tailscaled binary; move it to the
'tailscale debug' CLI that is available on all platforms instead,
accessed over LocalAPI.
Updates #7377
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I47bffe4461e036fab577c2e51e173f4003592ff7
Uses the hooks added by tailscale/go#45 to instrument the reads and
writes on the major code paths that do network I/O in the client. The
convention is to use "<package>.<type>:<label>" as the annotation for
the responsible code path.
Enabled on iOS, macOS and Android only, since mobile platforms are the
ones we're most interested in, and we are less sensitive to any
throughput degradation due to the per-I/O callback overhead (macOS is
also enabled for ease of testing during development).
For now just exposed as counters on a /v0/sockstats PeerAPI endpoint.
We also keep track of the current interface so that we can break out
the stats by interface.
Updates tailscale/corp#9230
Updates #3363
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
To aid in debugging where a customer has static port-forwards set up and
there are issues establishing a connection through that port.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ic5558bcdb40c9119b83f79dcacf2233b07777f2a
Update all code generation tools, and those that check for license
headers to use the new standard header.
Also update copyright statement in LICENSE file.
Fixes#6865
Signed-off-by: Will Norris <will@tailscale.com>
This updates all source files to use a new standard header for copyright
and license declaration. Notably, copyright no longer includes a date,
and we now use the standard SPDX-License-Identifier header.
This commit was done almost entirely mechanically with perl, and then
some minimal manual fixes.
Updates #6865
Signed-off-by: Will Norris <will@tailscale.com>
The single packet WriteTo() through RebindingUDPConn.WriteBatch() was
not checking for a rebind between loading the PacketConn and writing to
it. Same with ReadFrom()/ReadBatch().
Fixes#6989
Signed-off-by: Jordan Whited <jordan@tailscale.com>
When you hit control-C on a tailscaled (notably in dev mode, but
also on any systemctl stop/restart), there is a flood of messages like:
magicsock: doing cleanup for discovery key d:aa9c92321db0807f
magicsock: doing cleanup for discovery key d:bb0f16aacadbfd46
magicsock: doing cleanup for discovery key d:b5b2d386296536f2
magicsock: doing cleanup for discovery key d:3b640649f6796c91
magicsock: doing cleanup for discovery key d:71d7b1afbcce52cd
magicsock: doing cleanup for discovery key d:315b61d7e0111377
magicsock: doing cleanup for discovery key d:9301f63dce69bf45
magicsock: doing cleanup for discovery key d:376141884d6fe072
....
It can be hundreds or even tens of thousands.
So don't do that. Not a useful log message during shutdown.
Change-Id: I029a8510741023f740877df28adff778246c18e5
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
The Tailscale logging service has a hard limit on the maximum
log message size that can be accepted.
We want to ensure that netlog messages never exceed
this limit otherwise a client cannot transmit logs.
Move the goroutine for periodically dumping netlog messages
from wgengine/netlog to net/connstats.
This allows net/connstats to manage when it dumps messages,
either based on time or by size.
Updates tailscale/corp#8427
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
This is temporary while we work to upstream performance work in
https://github.com/WireGuard/wireguard-go/pull/64. A replace directive
is less ideal as it breaks dependent code without duplication of the
directive.
Signed-off-by: Jordan Whited <jordan@tailscale.com>
This commit updates the wireguard-go dependency and implements the
necessary changes to the tun.Device and conn.Bind implementations to
support passing vectors of packets in tailscaled. This significantly
improves throughput performance on Linux.
Updates #414
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Signed-off-by: James Tucker <james@tailscale.com>
Co-authored-by: James Tucker <james@tailscale.com>
We would replace the existing real implementation of nettype.PacketConn
with a blockForeverConn, but that violates the contract of atomic.Value
(where the type cannot change). Fix by switching to a pointer value
(atomic.Pointer[nettype.PacketConn]).
A longstanding issue, but became more prevalent when we started binding
connections to interfaces on macOS and iOS (#6566), which could lead to
the bind call failing if the interface was no longer available.
Fixes#6641
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
Previously, tstun.Wrapper and magicsock.Conn managed their
own statistics data structure and relied on an external call to
Extract to extract (and reset) the statistics.
This makes it difficult to ensure a maximum size on the statistics
as the caller has no introspection into whether the number
of unique connections is getting too large.
Invert the control flow such that a *connstats.Statistics
is registered with tstun.Wrapper and magicsock.Conn.
Methods on non-nil *connstats.Statistics are called for every packet.
This allows the implementation of connstats.Statistics (in the future)
to better control when it needs to flush to ensure
bounds on maximum sizes.
The value registered into tstun.Wrapper and magicsock.Conn could
be an interface, but that has two performance detriments:
1. Method calls on interface values are more expensive since
they must go through a virtual method dispatch.
2. The implementation would need a sync.Mutex to protect the
statistics value instead of using an atomic.Pointer.
Given that methods on constats.Statistics are called for every packet,
we want reduce the CPU cost on this hot path.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
There aren't any in the wild, other than one we ran on purpose to keep
us honest, but we can bump that one forward to 0.100.
Change-Id: I129e70724b2d3f8edf3b496dc01eba3ac5a2a907
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
