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f22185cae1
Fixes #1886.
Signed-off-by: David Anderson <danderson@tailscale.com>
(cherry picked from commit 6690f86ef4)
107 lines
3.0 KiB
Go
107 lines
3.0 KiB
Go
// Copyright (c) 2020 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 dns
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import (
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"sort"
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"inet.af/netaddr"
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"tailscale.com/util/dnsname"
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)
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// Config is a DNS configuration.
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type Config struct {
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// DefaultResolvers are the DNS resolvers to use for DNS names
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// which aren't covered by more specific per-domain routes below.
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// If empty, the OS's default resolvers (the ones that predate
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// Tailscale altering the configuration) are used.
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DefaultResolvers []netaddr.IPPort
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// Routes maps a DNS suffix to the resolvers that should be used
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// for queries that fall within that suffix.
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// If a query doesn't match any entry in Routes, the
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// DefaultResolvers are used.
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Routes map[dnsname.FQDN][]netaddr.IPPort
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// SearchDomains are DNS suffixes to try when expanding
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// single-label queries.
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SearchDomains []dnsname.FQDN
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// Hosts maps DNS FQDNs to their IPs, which can be a mix of IPv4
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// and IPv6.
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// Queries matching entries in Hosts are resolved locally by
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// 100.100.100.100 without leaving the machine.
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// Adding an entry to Hosts merely creates the record. If you want
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// it to resolve, you also need to add appropriate routes to
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// Routes.
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Hosts map[dnsname.FQDN][]netaddr.IP
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// AuthoritativeSuffixes is a list of fully-qualified DNS suffixes
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// for which the in-process Tailscale resolver is authoritative.
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// Queries for names within AuthoritativeSuffixes can only be
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// fulfilled by entries in Hosts. Queries with no match in Hosts
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// return NXDOMAIN.
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AuthoritativeSuffixes []dnsname.FQDN
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}
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// needsAnyResolvers reports whether c requires a resolver to be set
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// at the OS level.
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func (c Config) needsOSResolver() bool {
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return c.hasDefaultResolvers() || c.hasRoutes()
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}
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func (c Config) hasRoutes() bool {
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return len(c.Routes) > 0
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}
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// hasDefaultResolversOnly reports whether the only resolvers in c are
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// DefaultResolvers.
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func (c Config) hasDefaultResolversOnly() bool {
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return c.hasDefaultResolvers() && !c.hasRoutes()
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}
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func (c Config) hasDefaultResolvers() bool {
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return len(c.DefaultResolvers) > 0
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}
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// singleResolverSet returns the resolvers used by c.Routes if all
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// routes use the same resolvers, or nil if multiple sets of resolvers
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// are specified.
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func (c Config) singleResolverSet() []netaddr.IPPort {
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var first []netaddr.IPPort
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for _, resolvers := range c.Routes {
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if first == nil {
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first = resolvers
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continue
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}
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if !sameIPPorts(first, resolvers) {
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return nil
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}
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}
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return first
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}
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// matchDomains returns the list of match suffixes needed by Routes.
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func (c Config) matchDomains() []dnsname.FQDN {
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ret := make([]dnsname.FQDN, 0, len(c.Routes))
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for suffix := range c.Routes {
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ret = append(ret, suffix)
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}
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sort.Slice(ret, func(i, j int) bool {
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return ret[i].WithTrailingDot() < ret[j].WithTrailingDot()
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})
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return ret
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}
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func sameIPPorts(a, b []netaddr.IPPort) bool {
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if len(a) != len(b) {
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return false
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}
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for i := range a {
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if a[i] != b[i] {
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return false
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}
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}
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return true
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}
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