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tailscale/types/dnstype/dnstype.go

55 lines
1.9 KiB
Go

// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package dnstype defines types for working with DNS.
package dnstype
//go:generate go run tailscale.com/cmd/viewer --type=Resolver --clonefunc=true
import (
"net/netip"
)
// Resolver is the configuration for one DNS resolver.
type Resolver struct {
// Addr is the address of the DNS resolver, one of:
// - A plain IP address for a "classic" UDP+TCP DNS resolver.
// This is the common format as sent by the control plane.
// - An IP:port, for tests.
// - "https://resolver.com/path" for DNS over HTTPS; currently
// as of 2022-09-08 only used for certain well-known resolvers
// (see the publicdns package) for which the IP addresses to dial DoH are
// known ahead of time, so bootstrap DNS resolution is not required.
// - [TODO] "tls://resolver.com" for DNS over TCP+TLS
Addr string `json:",omitempty"`
// BootstrapResolution is an optional suggested resolution for the
// DoT/DoH resolver, if the resolver URL does not reference an IP
// address directly.
// BootstrapResolution may be empty, in which case clients should
// look up the DoT/DoH server using their local "classic" DNS
// resolver.
//
// As of 2022-09-08, BootstrapResolution is not yet used.
BootstrapResolution []netip.Addr `json:",omitempty"`
}
// IPPort returns r.Addr as an IP address and port if either
// r.Addr is an IP address (the common case) or if r.Addr
// is an IP:port (as done in tests).
func (r *Resolver) IPPort() (ipp netip.AddrPort, ok bool) {
if r.Addr == "" || r.Addr[0] == 'h' || r.Addr[0] == 't' {
// Fast path to avoid ParseIP error allocation for obviously not IP
// cases.
return
}
if ip, err := netip.ParseAddr(r.Addr); err == nil {
return netip.AddrPortFrom(ip, 53), true
}
if ipp, err := netip.ParseAddrPort(r.Addr); err == nil {
return ipp, true
}
return
}