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b8f89c93ac
If we lose our connection to the control server (e.g. due to a restart, or a network blip, etc), try reconnecting to the same address first before going through the whole control dialplan and/or DNS flow. This ensures that we're a bit "sticky", which makes load balancing easier by improving the chances that this client will hit a server with a warm cache. It also reduces the thundering herd of requests that hit other servers after we restart a single one. Updates #TODO Signed-off-by: Andrew Dunham <andrew@du.nham.ca> Change-Id: I6c3ef0b088468a8888c05cf8e3813056118ec835
111 lines
2.9 KiB
Go
111 lines
2.9 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package controlhttp
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import (
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"net/http"
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"net/netip"
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"net/url"
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"time"
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"tailscale.com/net/dnscache"
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"tailscale.com/net/netmon"
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"tailscale.com/tailcfg"
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"tailscale.com/tstime"
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"tailscale.com/types/key"
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"tailscale.com/types/logger"
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)
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const (
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// upgradeHeader is the value of the Upgrade HTTP header used to
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// indicate the Tailscale control protocol.
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upgradeHeaderValue = "tailscale-control-protocol"
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// handshakeHeaderName is the HTTP request header that can
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// optionally contain base64-encoded initial handshake
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// payload, to save an RTT.
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handshakeHeaderName = "X-Tailscale-Handshake"
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// serverUpgradePath is where the server-side HTTP handler to
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// to do the protocol switch is located.
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serverUpgradePath = "/ts2021"
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)
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// Dialer contains configuration on how to dial the Tailscale control server.
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type Dialer struct {
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// Hostname is the hostname to connect to, with no port number.
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//
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// This field is required.
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Hostname string
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// MachineKey contains the current machine's private key.
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//
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// This field is required.
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MachineKey key.MachinePrivate
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// ControlKey contains the expected public key for the control server.
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//
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// This field is required.
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ControlKey key.MachinePublic
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// ProtocolVersion is the expected protocol version to negotiate.
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//
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// This field is required.
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ProtocolVersion uint16
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// HTTPPort is the port number to use when making a HTTP connection.
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//
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// If not specified, this defaults to port 80.
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HTTPPort string
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// HTTPSPort is the port number to use when making a HTTPS connection.
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//
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// If not specified, this defaults to port 443.
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HTTPSPort string
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// Dialer is the dialer used to make outbound connections.
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//
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// If not specified, this defaults to net.Dialer.DialContext.
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Dialer dnscache.DialContextFunc
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// DNSCache is the caching Resolver used by this Dialer.
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//
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// If not specified, a new Resolver is created per attempt.
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DNSCache *dnscache.Resolver
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// Logf, if set, is a logging function to use; if unset, logs are
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// dropped.
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Logf logger.Logf
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NetMon *netmon.Monitor
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// DialPlan, if set, contains instructions from the control server on
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// how to connect to it. If present, we will try the methods in this
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// plan before falling back to DNS.
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DialPlan *tailcfg.ControlDialPlan
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// LastServerAddr, if valid, is the address that was last used to
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// (successfully) connect to the control server. It will be prioritized
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// when making a connection to the server.
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LastServerAddr netip.Addr
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proxyFunc func(*http.Request) (*url.URL, error) // or nil
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// For tests only
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drainFinished chan struct{}
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omitCertErrorLogging bool
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testFallbackDelay time.Duration
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// tstime.Clock is used instead of time package for methods such as time.Now.
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// If not specified, will default to tstime.StdClock{}.
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Clock tstime.Clock
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}
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func strDef(v1, v2 string) string {
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if v1 != "" {
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return v1
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}
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return v2
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}
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