mirror of
https://github.com/Control-D-Inc/ctrld.git
synced 2026-02-03 22:18:39 +00:00
fa50cd4df4
Instead of re-query DNS record for upstream when re-bootstrapping, just query all records on startup, then selecting the next bootstrap ip depends on the current network stack.
108 lines
2.1 KiB
Go
108 lines
2.1 KiB
Go
package net
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import (
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"context"
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"net"
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"sync"
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"sync/atomic"
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"time"
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"tailscale.com/logtail/backoff"
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)
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const (
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controldIPv6Test = "ipv6.controld.io"
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controldIPv4Test = "ipv4.controld.io"
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bootstrapDNS = "76.76.2.0:53"
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)
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var Dialer = &net.Dialer{
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Resolver: &net.Resolver{
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PreferGo: true,
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Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
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d := net.Dialer{
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Timeout: 10 * time.Second,
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}
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return d.DialContext(ctx, "udp", bootstrapDNS)
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},
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},
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}
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var (
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stackOnce atomic.Pointer[sync.Once]
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ipv4Enabled bool
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ipv6Enabled bool
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canListenIPv6Local bool
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hasNetworkUp bool
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)
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func init() {
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stackOnce.Store(new(sync.Once))
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}
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func supportIPv4() bool {
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_, err := Dialer.Dial("tcp4", net.JoinHostPort(controldIPv4Test, "80"))
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return err == nil
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}
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func supportIPv6() bool {
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_, err := Dialer.Dial("tcp6", net.JoinHostPort(controldIPv6Test, "80"))
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return err == nil
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}
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func supportListenIPv6Local() bool {
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if ln, err := net.Listen("tcp6", "[::1]:0"); err == nil {
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ln.Close()
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return true
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}
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return false
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}
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func probeStack() {
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b := backoff.NewBackoff("probeStack", func(format string, args ...any) {}, time.Minute)
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for {
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if _, err := Dialer.Dial("udp", bootstrapDNS); err == nil {
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hasNetworkUp = true
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break
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} else {
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b.BackOff(context.Background(), err)
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}
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}
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ipv4Enabled = supportIPv4()
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ipv6Enabled = supportIPv6()
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canListenIPv6Local = supportListenIPv6Local()
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}
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func Up() bool {
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stackOnce.Load().Do(probeStack)
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return hasNetworkUp
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}
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func SupportsIPv4() bool {
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stackOnce.Load().Do(probeStack)
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return ipv4Enabled
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}
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func SupportsIPv6() bool {
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stackOnce.Load().Do(probeStack)
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return ipv6Enabled
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}
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func SupportsIPv6ListenLocal() bool {
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stackOnce.Load().Do(probeStack)
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return canListenIPv6Local
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}
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// IPv6Available is like SupportsIPv6, but always do the check without caching.
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func IPv6Available() bool {
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return supportIPv6()
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}
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// IsIPv6 checks if the provided IP is v6.
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//
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//lint:ignore U1000 use in os_windows.go
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func IsIPv6(ip string) bool {
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parsedIP := net.ParseIP(ip)
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return parsedIP != nil && parsedIP.To4() == nil && parsedIP.To16() != nil
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}
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