Will Norris
3ec5be3f51
This file was never truly necessary and has never actually been used in the history of Tailscale's open source releases. A Brief History of AUTHORS files --- The AUTHORS file was a pattern developed at Google, originally for Chromium, then adopted by Go and a bunch of other projects. The problem was that Chromium originally had a copyright line only recognizing Google as the copyright holder. Because Google (and most open source projects) do not require copyright assignemnt for contributions, each contributor maintains their copyright. Some large corporate contributors then tried to add their own name to the copyright line in the LICENSE file or in file headers. This quickly becomes unwieldy, and puts a tremendous burden on anyone building on top of Chromium, since the license requires that they keep all copyright lines intact. The compromise was to create an AUTHORS file that would list all of the copyright holders. The LICENSE file and source file headers would then include that list by reference, listing the copyright holder as "The Chromium Authors". This also become cumbersome to simply keep the file up to date with a high rate of new contributors. Plus it's not always obvious who the copyright holder is. Sometimes it is the individual making the contribution, but many times it may be their employer. There is no way for the proejct maintainer to know. Eventually, Google changed their policy to no longer recommend trying to keep the AUTHORS file up to date proactively, and instead to only add to it when requested: https://opensource.google/docs/releasing/authors. They are also clear that: > Adding contributors to the AUTHORS file is entirely within the > project's discretion and has no implications for copyright ownership. It was primarily added to appease a small number of large contributors that insisted that they be recognized as copyright holders (which was entirely their right to do). But it's not truly necessary, and not even the most accurate way of identifying contributors and/or copyright holders. In practice, we've never added anyone to our AUTHORS file. It only lists Tailscale, so it's not really serving any purpose. It also causes confusion because Tailscalars put the "Tailscale Inc & AUTHORS" header in other open source repos which don't actually have an AUTHORS file, so it's ambiguous what that means. Instead, we just acknowledge that the contributors to Tailscale (whoever they are) are copyright holders for their individual contributions. We also have the benefit of using the DCO (developercertificate.org) which provides some additional certification of their right to make the contribution. The source file changes were purely mechanical with: git ls-files | xargs sed -i -e 's/\(Tailscale Inc &\) AUTHORS/\1 contributors/g' Updates #cleanup Change-Id: Ia101a4a3005adb9118051b3416f5a64a4a45987d Signed-off-by: Will Norris <will@tailscale.com>
350 lines
13 KiB
Go
350 lines
13 KiB
Go
// Copyright (c) Tailscale Inc & contributors
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// SPDX-License-Identifier: BSD-3-Clause
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// Package publicdns contains mapping and helpers for working with
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// public DNS providers.
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package publicdns
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import (
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"bytes"
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"encoding/binary"
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"encoding/hex"
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"fmt"
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"log"
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"math/big"
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"net/netip"
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"sort"
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"strconv"
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"strings"
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"sync"
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"tailscale.com/feature/buildfeatures"
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)
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// dohOfIP maps from public DNS IPs to their DoH base URL.
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//
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// This does not include NextDNS which is handled specially.
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var dohOfIP = map[netip.Addr]string{} // 8.8.8.8 => "https://..."
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var dohIPsOfBase = map[string][]netip.Addr{}
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var populateOnce sync.Once
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const (
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nextDNSBase = "https://dns.nextdns.io/"
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controlDBase = "https://dns.controld.com/"
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)
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// DoHEndpointFromIP returns the DNS-over-HTTPS base URL for a given IP
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// and whether it's DoH-only (not speaking DNS on port 53).
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//
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// The ok result is whether the IP is a known DNS server.
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func DoHEndpointFromIP(ip netip.Addr) (dohBase string, dohOnly bool, ok bool) {
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populateOnce.Do(populate)
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if b, ok := dohOfIP[ip]; ok {
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return b, false, true
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}
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// NextDNS DoH URLs are of the form "https://dns.nextdns.io/c3a884"
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// where the path component is the lower 12 bytes of the IPv6 address
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// in lowercase hex without any zero padding.
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if nextDNSv6RangeA.Contains(ip) || nextDNSv6RangeB.Contains(ip) {
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a := ip.As16()
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var sb strings.Builder
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sb.Grow(len(nextDNSBase) + 12)
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sb.WriteString(nextDNSBase)
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for _, b := range bytes.TrimLeft(a[4:], "\x00") {
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fmt.Fprintf(&sb, "%02x", b)
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}
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return sb.String(), true, true
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}
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// Control D DoH URLs are of the form "https://dns.controld.com/8yezwenugs"
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// where the path component is represented by 8 bytes (7-14) of the IPv6 address in base36
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if controlDv6RangeA.Contains(ip) || controlDv6RangeB.Contains(ip) {
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path := big.NewInt(0).SetBytes(ip.AsSlice()[6:14]).Text(36)
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return controlDBase + path, true, true
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}
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return "", false, false
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}
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// KnownDoHPrefixes returns the list of DoH base URLs.
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//
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// It returns a new copy each time, sorted. It's meant for tests.
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//
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// It does not include providers that have customer-specific DoH URLs like
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// NextDNS.
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func KnownDoHPrefixes() []string {
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populateOnce.Do(populate)
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ret := make([]string, 0, len(dohIPsOfBase))
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for b := range dohIPsOfBase {
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ret = append(ret, b)
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}
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sort.Strings(ret)
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return ret
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}
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func isSlashOrQuestionMark(r rune) bool {
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return r == '/' || r == '?'
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}
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// DoHIPsOfBase returns the IP addresses to use to dial the provided DoH base
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// URL.
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//
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// It is basically the inverse of DoHEndpointFromIP with the exception that for
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// NextDNS it returns IPv4 addresses that DoHEndpointFromIP doesn't map back.
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func DoHIPsOfBase(dohBase string) []netip.Addr {
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populateOnce.Do(populate)
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if s := dohIPsOfBase[dohBase]; len(s) > 0 {
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return s
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}
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if hexStr, ok := strings.CutPrefix(dohBase, nextDNSBase); ok {
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// The path is of the form /<profile-hex>[/<hostname>/<model>/<device id>...]
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// or /<profile-hex>?<query params>
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// but only the <profile-hex> is required. Ignore the rest:
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if i := strings.IndexFunc(hexStr, isSlashOrQuestionMark); i != -1 {
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hexStr = hexStr[:i]
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}
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// TODO(bradfitz): using the NextDNS anycast addresses works but is not
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// ideal. Some of their regions have better latency via a non-anycast IP
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// which we could get by first resolving A/AAAA "dns.nextdns.io" over
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// DoH using their anycast address. For now we only use the anycast
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// addresses. The IPv4 IPs we use are just the first one in their ranges.
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// For IPv6 we put the profile ID in the lower bytes, but that seems just
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// conventional for them and not required (it'll already be in the DoH path).
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// (Really we shouldn't use either IPv4 or IPv6 anycast for DoH once we
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// resolve "dns.nextdns.io".)
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if b, err := hex.DecodeString(hexStr); err == nil && len(b) <= 12 && len(b) > 0 {
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return []netip.Addr{
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nextDNSv4One,
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nextDNSv4Two,
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nextDNSv6Gen(nextDNSv6RangeA.Addr(), b),
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nextDNSv6Gen(nextDNSv6RangeB.Addr(), b),
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}
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}
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}
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if pathStr, ok := strings.CutPrefix(dohBase, controlDBase); ok {
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if i := strings.IndexFunc(pathStr, isSlashOrQuestionMark); i != -1 {
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pathStr = pathStr[:i]
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}
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return []netip.Addr{
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controlDv4One,
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controlDv4Two,
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controlDv6Gen(controlDv6RangeA.Addr(), pathStr),
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controlDv6Gen(controlDv6RangeB.Addr(), pathStr),
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}
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}
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return nil
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}
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// DoHV6 returns the first IPv6 DNS address from a given public DNS provider
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// if found, along with a boolean indicating success.
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func DoHV6(base string) (ip netip.Addr, ok bool) {
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populateOnce.Do(populate)
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for _, ip := range dohIPsOfBase[base] {
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if ip.Is6() {
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return ip, true
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}
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}
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return ip, false
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}
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// addDoH parses a given well-formed ip string into a netip.Addr type and
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// adds it to both knownDoH and dohIPsOFBase maps.
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func addDoH(ipStr, base string) {
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ip := netip.MustParseAddr(ipStr)
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dohOfIP[ip] = base
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dohIPsOfBase[base] = append(dohIPsOfBase[base], ip)
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}
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const (
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wikimediaDNSv4 = "185.71.138.138"
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wikimediaDNSv6 = "2001:67c:930::1"
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)
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// populate is called once to initialize the knownDoH and dohIPsOfBase maps.
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func populate() {
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if !buildfeatures.HasDNS {
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return
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}
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// Cloudflare
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// https://developers.cloudflare.com/1.1.1.1/ip-addresses/
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addDoH("1.1.1.1", "https://cloudflare-dns.com/dns-query")
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addDoH("1.0.0.1", "https://cloudflare-dns.com/dns-query")
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addDoH("2606:4700:4700::1111", "https://cloudflare-dns.com/dns-query")
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addDoH("2606:4700:4700::1001", "https://cloudflare-dns.com/dns-query")
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// Cloudflare -Malware
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addDoH("1.1.1.2", "https://security.cloudflare-dns.com/dns-query")
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addDoH("1.0.0.2", "https://security.cloudflare-dns.com/dns-query")
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addDoH("2606:4700:4700::1112", "https://security.cloudflare-dns.com/dns-query")
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addDoH("2606:4700:4700::1002", "https://security.cloudflare-dns.com/dns-query")
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// Cloudflare -Malware -Adult
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addDoH("1.1.1.3", "https://family.cloudflare-dns.com/dns-query")
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addDoH("1.0.0.3", "https://family.cloudflare-dns.com/dns-query")
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addDoH("2606:4700:4700::1113", "https://family.cloudflare-dns.com/dns-query")
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addDoH("2606:4700:4700::1003", "https://family.cloudflare-dns.com/dns-query")
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// Google
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addDoH("8.8.8.8", "https://dns.google/dns-query")
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addDoH("8.8.4.4", "https://dns.google/dns-query")
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addDoH("2001:4860:4860::8888", "https://dns.google/dns-query")
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addDoH("2001:4860:4860::8844", "https://dns.google/dns-query")
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// OpenDNS
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// TODO(bradfitz): OpenDNS is unique amongst this current set in that
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// its DoH DNS names resolve to different IPs than its normal DNS
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// IPs. Support that later. For now we assume that they're the same.
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// addDoH("208.67.222.222", "https://doh.opendns.com/dns-query")
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// addDoH("208.67.220.220", "https://doh.opendns.com/dns-query")
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// addDoH("208.67.222.123", "https://doh.familyshield.opendns.com/dns-query")
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// addDoH("208.67.220.123", "https://doh.familyshield.opendns.com/dns-query")
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// Quad9
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// https://www.quad9.net/service/service-addresses-and-features
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addDoH("9.9.9.9", "https://dns.quad9.net/dns-query")
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addDoH("149.112.112.112", "https://dns.quad9.net/dns-query")
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addDoH("2620:fe::fe", "https://dns.quad9.net/dns-query")
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addDoH("2620:fe::9", "https://dns.quad9.net/dns-query")
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// Quad9 +ECS +DNSSEC
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addDoH("9.9.9.11", "https://dns11.quad9.net/dns-query")
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addDoH("149.112.112.11", "https://dns11.quad9.net/dns-query")
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addDoH("2620:fe::11", "https://dns11.quad9.net/dns-query")
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addDoH("2620:fe::fe:11", "https://dns11.quad9.net/dns-query")
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// Quad9 -DNSSEC
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addDoH("9.9.9.10", "https://dns10.quad9.net/dns-query")
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addDoH("149.112.112.10", "https://dns10.quad9.net/dns-query")
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addDoH("2620:fe::10", "https://dns10.quad9.net/dns-query")
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addDoH("2620:fe::fe:10", "https://dns10.quad9.net/dns-query")
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// Mullvad
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// See https://mullvad.net/en/help/dns-over-https-and-dns-over-tls/
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// Mullvad (default)
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addDoH("194.242.2.2", "https://dns.mullvad.net/dns-query")
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addDoH("2a07:e340::2", "https://dns.mullvad.net/dns-query")
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// Mullvad (adblock)
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addDoH("194.242.2.3", "https://adblock.dns.mullvad.net/dns-query")
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addDoH("2a07:e340::3", "https://adblock.dns.mullvad.net/dns-query")
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// Mullvad (base)
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addDoH("194.242.2.4", "https://base.dns.mullvad.net/dns-query")
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addDoH("2a07:e340::4", "https://base.dns.mullvad.net/dns-query")
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// Mullvad (extended)
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addDoH("194.242.2.5", "https://extended.dns.mullvad.net/dns-query")
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addDoH("2a07:e340::5", "https://extended.dns.mullvad.net/dns-query")
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// Mullvad (family)
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addDoH("194.242.2.6", "https://family.dns.mullvad.net/dns-query")
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addDoH("2a07:e340::6", "https://family.dns.mullvad.net/dns-query")
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// Mullvad (all)
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addDoH("194.242.2.9", "https://all.dns.mullvad.net/dns-query")
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addDoH("2a07:e340::9", "https://all.dns.mullvad.net/dns-query")
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// Wikimedia
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addDoH(wikimediaDNSv4, "https://wikimedia-dns.org/dns-query")
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addDoH(wikimediaDNSv6, "https://wikimedia-dns.org/dns-query")
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// Control D
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addDoH("76.76.2.0", "https://freedns.controld.com/p0")
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addDoH("76.76.10.0", "https://freedns.controld.com/p0")
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addDoH("2606:1a40::", "https://freedns.controld.com/p0")
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addDoH("2606:1a40:1::", "https://freedns.controld.com/p0")
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// Control D -Malware
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addDoH("76.76.2.1", "https://freedns.controld.com/p1")
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addDoH("76.76.10.1", "https://freedns.controld.com/p1")
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addDoH("2606:1a40::1", "https://freedns.controld.com/p1")
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addDoH("2606:1a40:1::1", "https://freedns.controld.com/p1")
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// Control D -Malware + Ads
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addDoH("76.76.2.2", "https://freedns.controld.com/p2")
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addDoH("76.76.10.2", "https://freedns.controld.com/p2")
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addDoH("2606:1a40::2", "https://freedns.controld.com/p2")
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addDoH("2606:1a40:1::2", "https://freedns.controld.com/p2")
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// Control D -Malware + Ads + Social
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addDoH("76.76.2.3", "https://freedns.controld.com/p3")
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addDoH("76.76.10.3", "https://freedns.controld.com/p3")
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addDoH("2606:1a40::3", "https://freedns.controld.com/p3")
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addDoH("2606:1a40:1::3", "https://freedns.controld.com/p3")
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// Control D -Malware + Ads + Adult
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addDoH("76.76.2.4", "https://freedns.controld.com/family")
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addDoH("76.76.10.4", "https://freedns.controld.com/family")
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addDoH("2606:1a40::4", "https://freedns.controld.com/family")
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addDoH("2606:1a40:1::4", "https://freedns.controld.com/family")
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}
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var (
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// The NextDNS IPv6 ranges (primary and secondary). The customer ID is
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// encoded in the lower bytes and is used (in hex form) as the DoH query
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// path.
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nextDNSv6RangeA = netip.MustParsePrefix("2a07:a8c0::/33")
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nextDNSv6RangeB = netip.MustParsePrefix("2a07:a8c1::/33")
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// The first two IPs in the /24 v4 ranges can be used for DoH to NextDNS.
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//
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// They're Anycast and usually okay, but NextDNS has some locations that
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// don't do BGP and can get results for querying them over DoH to find the
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// IPv4 address of "dns.mynextdns.io" and find an even better result.
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//
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// Note that the Tailscale DNS client does not do any of the "IP address
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// linking" that NextDNS can do with its IPv4 addresses. These addresses
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// are only used for DoH.
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nextDNSv4RangeA = netip.MustParsePrefix("45.90.28.0/24")
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nextDNSv4RangeB = netip.MustParsePrefix("45.90.30.0/24")
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nextDNSv4One = nextDNSv4RangeA.Addr()
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nextDNSv4Two = nextDNSv4RangeB.Addr()
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// Wikimedia DNS server IPs (anycast)
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wikimediaDNSv4Addr = netip.MustParseAddr(wikimediaDNSv4)
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wikimediaDNSv6Addr = netip.MustParseAddr(wikimediaDNSv6)
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// The Control D IPv6 ranges (primary and secondary). The customer ID is
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// encoded in the ipv6 address is used (in base 36 form) as the DoH query
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controlDv6RangeA = netip.MustParsePrefix("2606:1a40::/48")
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controlDv6RangeB = netip.MustParsePrefix("2606:1a40:1::/48")
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controlDv4One = netip.MustParseAddr("76.76.2.22")
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controlDv4Two = netip.MustParseAddr("76.76.10.22")
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)
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// nextDNSv6Gen generates a NextDNS IPv6 address from the upper 8 bytes in the
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// provided ip and using id as the lowest 0-8 bytes.
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func nextDNSv6Gen(ip netip.Addr, id []byte) netip.Addr {
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if len(id) > 12 {
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return netip.Addr{}
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}
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a := ip.As16()
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copy(a[16-len(id):], id)
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return netip.AddrFrom16(a)
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}
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// controlDv6Gen generates a Control D IPv6 address from provided ip and id.
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//
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// The id is taken from the DoH query path component and represents a unique resolver configuration.
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// e.g. https://dns.controld.com/hyq3ipr2ct
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func controlDv6Gen(ip netip.Addr, id string) netip.Addr {
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b := make([]byte, 8)
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decoded, err := strconv.ParseUint(id, 36, 64)
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if err != nil {
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log.Printf("controlDv6Gen: failed to parse id %q: %v", id, err)
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}
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binary.BigEndian.PutUint64(b, decoded)
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a := ip.AsSlice()
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copy(a[6:14], b)
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addr, _ := netip.AddrFromSlice(a)
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return addr
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}
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// IPIsDoHOnlyServer reports whether ip is a DNS server that should only use
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// DNS-over-HTTPS (not regular port 53 DNS).
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func IPIsDoHOnlyServer(ip netip.Addr) bool {
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return nextDNSv6RangeA.Contains(ip) || nextDNSv6RangeB.Contains(ip) ||
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nextDNSv4RangeA.Contains(ip) || nextDNSv4RangeB.Contains(ip) ||
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ip == wikimediaDNSv4Addr || ip == wikimediaDNSv6Addr ||
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controlDv6RangeA.Contains(ip) || controlDv6RangeB.Contains(ip) ||
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ip == controlDv4One || ip == controlDv4Two
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}
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