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2aade349fc
Clarify & verify that some DoH URLs can be sent over tailcfg in some limited cases. Updates #2452 Change-Id: Ibb25db77788629c315dc26285a1059a763989e24 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
55 lines
1.9 KiB
Go
55 lines
1.9 KiB
Go
// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package dnstype defines types for working with DNS.
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package dnstype
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//go:generate go run tailscale.com/cmd/viewer --type=Resolver --clonefunc=true
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import (
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"net/netip"
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)
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// Resolver is the configuration for one DNS resolver.
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type Resolver struct {
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// Addr is the address of the DNS resolver, one of:
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// - A plain IP address for a "classic" UDP+TCP DNS resolver.
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// This is the common format as sent by the control plane.
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// - An IP:port, for tests.
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// - "https://resolver.com/path" for DNS over HTTPS; currently
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// as of 2022-09-08 only used for certain well-known resolvers
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// (see the publicdns package) for which the IP addresses to dial DoH are
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// known ahead of time, so bootstrap DNS resolution is not required.
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// - [TODO] "tls://resolver.com" for DNS over TCP+TLS
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Addr string `json:",omitempty"`
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// BootstrapResolution is an optional suggested resolution for the
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// DoT/DoH resolver, if the resolver URL does not reference an IP
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// address directly.
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// BootstrapResolution may be empty, in which case clients should
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// look up the DoT/DoH server using their local "classic" DNS
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// resolver.
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//
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// As of 2022-09-08, BootstrapResolution is not yet used.
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BootstrapResolution []netip.Addr `json:",omitempty"`
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}
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// IPPort returns r.Addr as an IP address and port if either
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// r.Addr is an IP address (the common case) or if r.Addr
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// is an IP:port (as done in tests).
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func (r *Resolver) IPPort() (ipp netip.AddrPort, ok bool) {
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if r.Addr == "" || r.Addr[0] == 'h' || r.Addr[0] == 't' {
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// Fast path to avoid ParseIP error allocation for obviously not IP
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// cases.
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return
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}
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if ip, err := netip.ParseAddr(r.Addr); err == nil {
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return netip.AddrPortFrom(ip, 53), true
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}
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if ipp, err := netip.ParseAddrPort(r.Addr); err == nil {
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return ipp, true
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}
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return
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}
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