* 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>
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>
Just because we get an HTTP upgrade response over port 80, don't
assume we'll be able to do bi-di Noise over it. There might be a MITM
corp proxy or anti-virus/firewall interfering. Do a bit more work to
validate the connection before proceeding to give up on the TLS port
443 dial.
Updates #4557 (probably fixes)
Change-Id: I0e1bcc195af21ad3d360ffe79daead730dfd86f1
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
The connections returned from SystemDial are automatically closed when
there is a major link change.
Also plumb through the dialer to the noise client so that connections
are auto-reset when moving from cellular to WiFi etc.
Updates #3363
Signed-off-by: Maisem Ali <maisem@tailscale.com>
Doing so makes development unpleasant, because we have to first break the
client by bumping to a version the control server rejects, then upgrade
the control server to make it accept the new version.
This strict rejection at handshake time is only necessary if we want to
blocklist some vulnerable protocol versions in the future. So, switch
to a default-permissive stance: until we have such a version that we
have to eagerly block early, we'll accept whatever version the client
presents, and leave it to the user of controlbase.Conn to make decisions
based on that version.
Noise still enforces that the client and server *agree* on what protocol
version is being used, and the control server still has the option to
finish the handshake and then hang up with an in-noise error, rather
than abort at the handshake level.
Updates #3488
Signed-off-by: David Anderson <danderson@tailscale.com>
This is so that we can plumb our client capability version through
the protocol as the Noise version. The capability version increments
more frequently than strictly required (the Noise version only needs
to change when cryptographically-significant changes are made to
the protocol, whereas the capability version also indicates changes
in non-cryptographically-significant parts of the protocol), but this
gives us a safe pre-auth way to determine if the client supports
future protocol features, while still relying on Noise's strong
assurance that the client and server have agreed on the same version.
Currently, the server executes the same protocol regardless of the
version number, and just presents the version to the caller so they
can do capability-based things in the upper RPC protocol. In future,
we may add a ratchet to disallow obsolete protocols, or vary the
Noise handshake behavior based on requested version.
Updates #3488
Signed-off-by: David Anderson <danderson@tailscale.com>
