This logs that the gateway/self IP address has changed if one of the new
values differs.
Updates #8992
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I0919424b68ad97fbe1204dd36317ed6f5915411f
Some routers don't support lease times for UPnP portmapping; let's fall
back to adding a permanent lease in these cases. Additionally, add a
proper end-to-end test case for the UPnP portmapping behaviour.
Updates #9343
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I17dec600b0595a5bfc9b4d530aff6ee3109a8b12
RELNOTE=Adds support for Wikimedia DNS
Updates #9255
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I4213c29e0f91ea5aa0304a5a026c32b6690fead9
This option allows logging the raw HTTP requests and responses that the
portmapper Client makes when using UPnP. This can be extremely helpful
when debugging strange UPnP issues with users' devices, and might allow
us to avoid having to instruct users to perform a packet capture.
Updates #8992
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I2c3cf6930b09717028deaff31738484cc9b008e4
Port 0 is interpreted, per the spec (but inconsistently among router
software) as requesting to map every single available port on the UPnP
gateway to the internal IP address. We'd previously avoided picking
ports below 1024 for one of the two UPnP methods (in #7457), and this
change moves that logic so that we avoid it in all cases.
Updates #8992
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I20d652c0cd47a24aef27f75c81f78ae53cc3c71e
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
If the absolute value of the difference between the current
PreferredDERP's latency and the best latency is <= 10ms, don't change
it and instead prefer the previous value.
This is in addition to the existing hysteresis that tries to remain
on the previous DERP region if the relative improvement is small, but
handles nodes that have low latency to >1 DERP region better.
Updates #8603
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I1e34c94178f8c9a68a69921c5bc0227337514c70
This allows providing additional information to the client about how to
select a home DERP region, such as preferring a given DERP region over
all others.
Updates #8603
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I7c4a270f31d8585112fab5408799ffba5b75266f
This allows sending logs from the "logpolicy" package (and associated
callees) to something other than the log package. The behaviour for
tailscaled remains the same, passing in log.Printf
Updates #8249
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ie1d43b75fa7281933d9225bffd388462c08a5f31
When performing a fallback DNS query, run the recursive resolver in a
separate goroutine and compare the results returned by the recursive
resolver with the results we get from "regular" bootstrap DNS. This will
allow us to gather data about whether the recursive DNS resolver works
better, worse, or about the same as "regular" bootstrap DNS.
Updates #5853
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ifa0b0cc9eeb0dccd6f7a3d91675fe44b3b34bd48
This package contains platform-independent abstractions for fetching
information about an open TCP connection.
Updates #8413
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I236657b1060d7e6a45efc7a2f6aacf474547a2fe
We've talked in the past about reworking how bootstrap DNS works to
instead do recursive DNS resolution from the root; this would better
support on-prem customers and Headscale users where the DERP servers
don't currently resolve their DNS server. This package is an initial
implementation of recursive resolution for A and AAAA records.
Updates #5853
Change-Id: Ibe974d78709b4b03674b47c4ef61f9a00addf8b4
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
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
Instead of renewing certificates based on whether or not they're expired
at a fixed 14-day period in the future, renew based on whether or not
we're more than 2/3 of the way through the certificate's lifetime. This
properly handles shorter-lived certificates without issue.
Updates #8204
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I5e82a9cadc427c010d04ce58c7f932e80dd571ea
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
This passes the *dnscache.Resolver down from the Direct client into the
Noise client and from there into the controlhttp client. This retains
the Resolver so that it can share state across calls instead of creating
a new resolver.
Updates #4845
Updates #6110
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ia5d6af1870f3b5b5d7dd5685d775dcf300aec7af
A follow-up PR will start using this field after we set it in our
production DERPMap.
Updates #7925
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Idb41b79e6055dddb8944f79d91ad4a186ace98c7
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
This is an exact copy of the files misc/set/set{,_test}.go from
tailscale/corp@a5415daa9c, plus the
license headers.
For use in #7877
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I712d09c6d1a180c6633abe3acf8feb59b27e2866
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 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
A LogKnob allows enabling logs with an envknob, netmap capability, and
manually, and calling a logging function when logs are enabled.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Id66c608d4e488bfd4eaa5e867a8d9289686748be
When running a SOCKS or HTTP proxy, configure the tshttpproxy package to
drop those addresses from any HTTP_PROXY or HTTPS_PROXY environment
variables.
Fixes#7407
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I6cd7cad7a609c639780484bad521c7514841764b
Since users can run tailscaled in a variety of ways (root, non-root,
non-root with process capabilities on Linux), this check will print the
current process permissions to the log to aid in debugging.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ida93a206123f98271a0c664775d0baba98b330c7
If multiple Go channels have a value (or are closed), receiving from
them all in a select will nondeterministically return one of the two
arms. In this case, it's possible that the hairpin check timer will have
expired between when we start checking and before we check at all, but
the hairpin packet has already been received. In such cases, we'd
nondeterministically set report.HairPinning.
Instead, check if we have a value in our results channel first, then
select on the value and timeout channel after. Also, add a test that
catches this particular failure.
Fixes#1795
Change-Id: I842ab0bd38d66fabc6cabf2c2c1bb9bd32febf35
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Move the assertions about our post-privilege-drop UID/GID out of the
conditional if statement and always run them; I haven't been able to
find a case where this would fail. Defensively add an envknob to disable
this feature, however, which we can remove after the 1.40 release.
Updates #7616
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Iaec3dba9248131920204bd6c6d34bbc57a148185
This makes it less likely that we trip over bugs like golang/go#1435.
Updates #7616
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ic28c03c3ad8ed5274a795c766b767fa876029f0e
On FreeBSD and Darwin, changing a process's supplementary groups with
setgroups(2) will also change the egid of the process, setting it to the
first entry in the provided list. This is distinct from the behaviour on
other platforms (and possibly a violation of the POSIX standard).
Because of this, on FreeBSD with no TTY, our incubator code would
previously not change the process's gid, because it would read the
newly-changed egid, compare it against the expected egid, and since they
matched, not change the gid. Because we didn't use the 'login' program
on FreeBSD without a TTY, this would propagate to a child process.
This could be observed by running "id -p" in two contexts. The expected
output, and the output returned when running from a SSH shell, is:
andrew@freebsd:~ $ id -p
uid andrew
groups andrew
However, when run via "ssh andrew@freebsd id -p", the output would be:
$ ssh andrew@freebsd id -p
login root
uid andrew
rgid wheel
groups andrew
(this could also be observed via "id -g -r" to print just the gid)
We fix this by pulling the details of privilege dropping out into their
own function and prepending the expected gid to the start of the list on
Darwin and FreeBSD.
Finally, we add some tests that run a child process, drop privileges,
and assert that the final UID/GID/additional groups are what we expect.
More information can be found in the following article:
https://www.usenix.org/system/files/login/articles/325-tsafrir.pdf
Updates #7616
Alternative to #7609
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I0e6513c31b121108b50fe561c89e5816d84a45b9
Prior to this change, if we were in the middle of a lite map update we'd
tear down the entire map session and restart it. With this change, we'll
cancel an in-flight lite map request up to 10 times and restart before
we tear down the streaming map request. We tear down everything after 10
retries to ensure that a steady stream of calls to sendNewMapRequest
doesn't fail to make progress by repeatedly canceling and restarting.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Co-authored-by: Maisem Ali <maisem@tailscale.com>
Change-Id: I9392bf8cf674e7a58ccd1e476039300a359ef3b1
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
This prevents a panic where we synthesize a new netmap in
setClientStatus after we've shut down and nil'd out the controlclient,
since that function expects to be called while connected to control.
Fixes#7392
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ib631eb90f34f6afa008d69bbb386f70da145e102
This ensures that any mappings that are created are correctly cleaned
up, instead of waiting for them to expire in the router.
Updates #7377
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I436248ee7740eded6d8adae5df525e785a8f7ccb
Per a packet capture provided, some gateways will reply to a UPnP
discovery packet with a UDP packet with a source port that does not come
from the UPnP port. Accept these packets with a log message.
Updates #7377
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I5d4d5b2a0275009ed60f15c20b484fe2025d094b
We were previously sending a lower-case "udp" protocol, whereas other
implementations like miniupnp send an upper-case "UDP" protocol. For
compatibility, use an upper-case protocol instead.
Updates #7377
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I4aed204f94e4d51b7a256d29917af1536cb1b70f
Some devices don't let you UPnP portmap a port below 1024, so let's just
avoid that range of ports entirely.
Updates #7377
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ib7603b1c9a019162cdc4fa21744a2cae48bb1d86
Return a mock set of interfaces and a mock gateway during this test and
verify that LikelyHomeRouterIP returns the outcome we expect. Also
verify that we return an error if there are no IPv4 addresses available.
Follow-up to #7447
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I8f06989e7f1f0bebd108861cbff17b820ed2e6e4
We weren't filtering out IPv6 addresses from this function, so we could
be returning an IPv4 gateway IP and an IPv6 self IP. Per the function
comments, only return IPv4 addresses for the self IP.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: If19a4aadc343fbd4383fc5290befa0eff006799e
Now that we're using rand.Shuffle in a few locations, create a generic
shuffle function and use it instead. While we're at it, move the
interleaveSlices function to the same package for use.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I0b00920e5b3eea846b6cedc30bd34d978a049fd3
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
This ensures that we're trying multiple returned IPs, since the DERP
servers return the same response to all queries. This should increase
the chances that we eventually reach a working IP.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ie8d4fb93df96da910fae49ae71bf3e402b9fdecc
Also add some basic tests for this implementation.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I307ebb6db91d0c172657befb276b38ccb638f828
This isn't currently supported due to missing support in upstream
dependencies, and also we don't use this package anywhere right now.
Just conditionally skip this for now.
Fixes#7268
Change-Id: Ie7389c2c0816b39b410c02a7276051a4c18b6450
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Previously, we only printed these at startup; print those when the user
generates a bugreport as we so we don't have to go spelunking through
the logs.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: If5b0970f09fcb4cf8839958af5d37f84e0ba6ed2
We now handle the case where the NetworkMap.SelfNode has already expired
and do not return an expiry time in the past (which causes an ~infinite
loop of timers to fire).
Additionally, we now add an explicit check to ensure that the next
expiry time is never before the current local-to-the-system time, to
ensure that we don't end up in a similar situation due to clock skew.
Finally, we add more tests for this logic to ensure that we don't
regress on these edge cases.
Fixes#7193
Change-Id: Iaf8e3d83be1d133a7aab7f8d62939e508cc53f9c
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Add the envknob TS_DEBUG_EXIT_NODE_DNS_NET_PKG, which enables more
verbose debug logging when calling the handleExitNodeDNSQueryWithNetPkg
function. This function is currently only called on Windows and Android.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ieb3ca7b98837d7dc69cd9ca47609c1c52e3afd7b
Having this information near the "user bugreport" line makes it easier
to identify the node and expiry without spelunking through the rest of
the logs.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I1597c783efc06574fa4c8f211e68d835f20b6ccb
Now that Go 1.20 is released, multierr.Error can implement
Unwrap() []error
Updates #7123
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ic28c2579de6799801836c447afbca8cdcba732cf
When we make a connection to a server, we previously would verify with
the system roots, and then fall back to verifying with our baked-in
Let's Encrypt root if the system root cert verification failed.
We now explicitly check for, and log a health error on, self-signed
certificates. Additionally, we now always verify against our baked-in
Let's Encrypt root certificate and log an error if that isn't
successful. We don't consider this a health failure, since if we ever
change our server certificate issuer in the future older non-updated
versions of Tailscale will no longer be healthy despite being able to
connect.
Updates #3198
Change-Id: I00be5ceb8afee544ee795e3c7a2815476abc4abf
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
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
We can log too quickly for logtail to catch up, even when we opt out of
log rate-limiting. When the user passes the --diagnose flag to
bugreport, we use a token bucket to control how many logs per second are
printed and sleep until we're able to write more.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: If27672d66b621b589280bd0fe228de367ffcbd8f
Follow-up to #7065 with some comments from Brad's review.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ia1219f4fa25479b2dada38ffe421065b408c5954
When turned on via environment variable (off by default), this will use
the BSD routing APIs to query what interface index a socket should be
bound to, rather than binding to the default interface in all cases.
Updates #5719
Updates #5940
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ib4c919471f377b7a08cd3413f8e8caacb29fee0b
This allows users to temporarily enable/disable dnscache logging via a
new node capability, to aid in debugging strange connectivity issues.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I46cf2596a8ae4c1913880a78d0033f8b668edc08
The current node isn't in NetMap.Peers, so without this we would not
have fired this timer on self expiry.
Updates #6932
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Id57f96985397e372f9226802d63b42ff92c95093
In order to be able to synthesize a new NetMap when a node expires, have
LocalBackend start a timer when receiving a new NetMap that fires
slightly after the next node expires. Additionally, move the logic that
updates expired nodes into LocalBackend so it runs on every netmap
(whether received from controlclient or self-triggered).
Updates #6932
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I833390e16ad188983eac29eb34cc7574f555f2f3
Nodes that are expired, taking into account the time delta calculated
from MapResponse.ControlTime have the newly-added Expired boolean set.
For additional defense-in-depth, also replicate what control does and
clear the Endpoints and DERP fields, and additionally set the node key
to a bogus value.
Updates #6932
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ia2bd6b56064416feee28aef5699ca7090940662a
These aren't handled, but it's not an error to get one.
Fixes#6806
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I1fcb9032ac36420aa72a048bf26f58360b9461f9
We saw a few cases where we hit this limit; bumping to 4k seems
relatively uncontroversial.
Change-Id: I218fee3bc0d2fa5fde16eddc36497a73ebd7cbda
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Previously, if a DNS-over-TCP message was received while there were
existing queries in-flight, and it was over the size limit, we'd close
the 'responses' channel. This would cause those in-flight queries to
send on the closed channel and panic.
Instead, don't close the channel at all and rely on s.ctx being
canceled, which will ensure that in-flight queries don't hang.
Fixes#6725
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I8267728ac37ed7ae38ddd09ce2633a5824320097
It's possible for the 'somethingChanged' callback to be registered and
then trigger before the ctx field is assigned; move the assignment
earlier so this can't happen.
Change-Id: Ia7ee8b937299014a083ab40adf31a8b3e0db4ec5
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Adjust the expected system output by removing the unsupported mask
component including and after the slash in expected output like:
fwmask 0xabc/0xdef
This package's tests now pass in an Alpine container when the 'go' and
'iptables' packages are installed (and run as privileged so /dev/net/tun
exists).
Fixes#5928
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Id1a3896282bfa36b64afaec7a47205e63ad88542
This handles the case where the inner *os.PathError is wrapped in
another error type, and additionally will redact errors of type
*os.LinkError. Finally, add tests to verify that redaction works.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ie83424ff6c85cdb29fb48b641330c495107aab7c
This uses a go:generate statement to create a bunch of .syso files that
contain a Windows resource file. We check these in since they're less
than 1KiB each, and are only included on Windows.
Fixes#6429
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I0512c3c0b2ab9d8d8509cf2037b88b81affcb81f
This sets the "com.apple.quarantine" flag on macOS, and the
"Zone.Identifier" alternate data stream on Windows.
Change-Id: If14f805467b0e2963067937d7f34e08ba1d1fa85
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
The ResolvConfMode property is documented to return how systemd-resolved
is currently managing /etc/resolv.conf. Include that information in the
debug line, when available, to assist in debugging DNS issues.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I1ae3a257df1d318d0193a8c7f135c458ec45093e
The Lufthansa in-flight wifi generates a synthetic 204 response to the
DERP server's /generate_204 endpoint. This PR adds a basic
challenge/response to the endpoint; something sufficiently complicated
that it's unlikely to be implemented by a captive portal. We can then
check for the expected response to verify whether we're being MITM'd.
Follow-up to #5601
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I94a68c9a16a7be7290200eea6a549b64f02ff48f
This is especially helpful as we launch newer DERPs over time, and older
clients have progressively out-of-date static DERP maps baked in. After
this, as long as the client has successfully connected once, it'll cache
the most recent DERP map it knows about.
Resolves an in-code comment from @bradfitz
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
This is entirely optional (i.e. failing in this code is non-fatal) and
only enabled on Linux for now. Additionally, this new behaviour can be
disabled by setting the TS_DEBUG_DISABLE_AF_PACKET environment variable.
Updates #3824
Replaces #5474
Co-authored-by: Andrew Dunham <andrew@du.nham.ca>
Signed-off-by: David Anderson <danderson@tailscale.com>
On sufficiently large tailnets, even writing the peer header (~95 bytes)
can result in a large amount of data that needs to be serialized and
deserialized. Only write headers for peers that need to have their
configuration changed.
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
I was working on my "dump iptables rules using only syscalls" branch and
had a bunch of C structure decoding to do. Rather than manually
calculating the padding or using unsafe trickery to actually cast
variable-length structures to Go types, I'd rather use a helper package
that deals with padding for me.
Padding rules were taken from the following article:
http://www.catb.org/esr/structure-packing/
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Andrew Dunham
