Instead of just falling back to making a TCP query to an upstream DNS
server when the UDP query returns a truncated query, also start a TCP
query in parallel with the UDP query after a given race timeout. This
ensures that if the upstream DNS server does not reply over UDP (or if
the response packet is blocked, or there's an error), we can still make
queries if the server replies to TCP queries.
This also adds a new package, util/race, to contain the logic required for
racing two different functions and returning the first non-error answer.
Updates tailscale/corp#14809
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I4311702016c1093b1beaa31b135da1def6d86316
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
This adds an initial and intentionally minimal configuration for
golang-ci, fixes the issues reported, and adds a GitHub Action to check
new pull requests against this linter configuration.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I8f38fbc315836a19a094d0d3e986758b9313f163
This package is an initial implementation of something that can read
netfilter and iptables rules from the Linux kernel without needing to
shell out to an external utility; it speaks directly to the kernel using
syscalls and parses the data returned.
Currently this is read-only since it only knows how to parse a subset of
the available data.
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
Change-Id: Iccadf5dcc081b73268d8ccf8884c24eb6a6f1ff5
If the user passes the --diagnose flag, print a warning if any of the
default or fallback DNS resolvers are Tailscale IPs. This can interfere
with the ability to connect to the controlplane, and is typically
something to pay attention to if there's a connectivity issue.
Change-Id: Ib14bf6228c037877fbdcd22b069212b1a4b2c456
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
Inspired by #6235, let's explicitly test the behaviour of this function
to ensure that we're not processing things we don't expect to.
Change-Id: I158050a63be7410fb99452089ea607aaf89fe91a
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
The derpers don't allow whitespace in the challenge.
Change-Id: I93a8b073b846b87854fba127b5c1d80db205f658
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
This switches from using an atomic.Bool to a mutex for reasons that are
described in the commit, and should address the flakes that we're still
seeing.
Fixes#3020
Change-Id: I4e39471c0eb95886db03020ea1ccf688c7564a11
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
This was tested by running 10000 test iterations and observing no flakes
after this change was made.
Change-Id: Ib036fd03a3a17800132c53c838cc32bfe2961306
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
It looks like this was left by mistake in 4a3e2842.
Change-Id: Ie4e3d5842548cd2e8533b3552298fb1ce9ba761a
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
We had previously added this to the netcheck report in #5087 but never
copied it into the NetInfo struct. Additionally, add it to log lines so
it's visible to support.
Change-Id: Ib6266f7c6aeb2eb2a28922aeafd950fe1bf5627e
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
Periodically poll the TCP RTT metric from all open TCP connections and
update a (bucketed) histogram metric.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I6214902196b05bf7829c9d0ea501ce0e13d984cf
This information is super helpful when debugging and it'd be nice to not
have to scroll around in the logs to find it near a bugreport.
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
* tailcfg, control/controlhttp, control/controlclient: add ControlDialPlan field
This field allows the control server to provide explicit information
about how to connect to it; useful if the client's link status can
change after the initial connection, or if the DNS settings pushed by
the control server break future connections.
Change-Id: I720afe6289ec27d40a41b3dcb310ec45bd7e5f3e
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
As the comment in the code says, netstack should always respond to ICMP
echo requests to a 4via6 address, even if the netstack instance isn't
normally processing subnet traffic.
Follow-up to #5709
Change-Id: I504d0776c5824071b2a2e0e687bc33e24f6c4746
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
This doesn't change any behaviour for now, other than maybe running a
full netcheck more often. The intent is to start gathering data on
captive portals, and additionally, seeing this in the 'tailscale
netcheck' command should provide a bit of additional information to
users.
Updates #1634
Change-Id: I6ba08f9c584dc0200619fa97f9fde1a319f25c76
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
This turns 'dialParams' into something more like net.Dialer, where
configuration fields are public on the struct.
Split out of #5648
Change-Id: I0c56fd151dc5489c3c94fb40d18fd639e06473bc
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
If we accept a forwarded TCP connection before dialing, we can
erroneously signal to a client that we support IPv6 (or IPv4) without
that actually being possible. Instead, we only complete the client's TCP
handshake after we've dialed the outbound connection; if that fails, we
respond with a RST.
Updates #5425 (maybe fixes!)
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
In addition to printing goroutine stacks, explicitly track all in-flight
operations and print them when the watchdog triggers (along with the
time they were started at). This should make debugging watchdog failures
easier, since we can look at the longest-running operation(s) first.
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
Prior to this change, if BIRD stops responding wgengine.watchdogEngine
will crash tailscaled.
This happens because in wgengine.userspaceEngine, we end up blocking
forever trying to write a request to or read a response from BIRD with
wgLock held, and then future watchdog'd calls will block on acquiring
that mutex until the watchdog kills the process. With the timeout, we at
least get the chance to print an error message and decide whether we
want to crash or not.
Updates tailscale/coral#72
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
Signed-off-by: Andrew Dunham <andrew@tailscale.com>
Andrew DunhamandGitHub
