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https://github.com/tailscale/tailscale.git
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b382161fe5
When a DNS server claims to be unable or unwilling to handle a request, instead of passing that refusal along to the client, just treat it as any other error trying to connect to the DNS server. This prevents DNS requests from failing based on if a server can respond with a transient error before another server is able to give an actual response. DNS requests only failing *sometimes* is really hard to find the cause of (#1033). Signed-off-by: Smitty <me@smitop.com>
143 lines
3.2 KiB
Go
143 lines
3.2 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 resolver
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import (
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"fmt"
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"net"
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"reflect"
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"strings"
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"testing"
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"time"
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dns "golang.org/x/net/dns/dnsmessage"
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"tailscale.com/types/dnstype"
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)
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func (rr resolverAndDelay) String() string {
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return fmt.Sprintf("%v+%v", rr.name, rr.startDelay)
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}
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func TestResolversWithDelays(t *testing.T) {
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// query
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q := func(ss ...string) (ipps []dnstype.Resolver) {
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for _, s := range ss {
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host, _, err := net.SplitHostPort(s)
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if err != nil {
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t.Fatal(err)
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}
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ipps = append(ipps, dnstype.Resolver{Addr: host})
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}
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return
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}
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// output
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o := func(ss ...string) (rr []resolverAndDelay) {
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for _, s := range ss {
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var d time.Duration
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if i := strings.Index(s, "+"); i != -1 {
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var err error
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d, err = time.ParseDuration(s[i+1:])
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if err != nil {
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panic(fmt.Sprintf("parsing duration in %q: %v", s, err))
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}
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s = s[:i]
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}
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host, _, err := net.SplitHostPort(s)
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if err != nil {
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t.Fatal(err)
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}
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rr = append(rr, resolverAndDelay{
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name: dnstype.Resolver{Addr: host},
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startDelay: d,
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})
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}
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return
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}
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tests := []struct {
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name string
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in []dnstype.Resolver
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want []resolverAndDelay
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}{
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{
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name: "unknown-no-delays",
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in: q("1.2.3.4:53", "2.3.4.5:53"),
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want: o("1.2.3.4:53", "2.3.4.5:53"),
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},
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{
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name: "google-all-ipv4",
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in: q("8.8.8.8:53", "8.8.4.4:53"),
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want: o("8.8.8.8:53", "8.8.4.4:53+200ms"),
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},
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{
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name: "google-only-ipv6",
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in: q("[2001:4860:4860::8888]:53", "[2001:4860:4860::8844]:53"),
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want: o("[2001:4860:4860::8888]:53", "[2001:4860:4860::8844]:53+200ms"),
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},
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{
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name: "google-all-four",
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in: q("8.8.8.8:53", "8.8.4.4:53", "[2001:4860:4860::8888]:53", "[2001:4860:4860::8844]:53"),
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want: o("8.8.8.8:53", "8.8.4.4:53+200ms", "[2001:4860:4860::8888]:53+2.5s", "[2001:4860:4860::8844]:53+2.7s"),
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},
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{
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name: "quad9-one-v4-one-v6",
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in: q("9.9.9.9:53", "[2620:fe::fe]:53"),
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want: o("9.9.9.9:53", "[2620:fe::fe]:53+200ms"),
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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got := resolversWithDelays(tt.in)
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if !reflect.DeepEqual(got, tt.want) {
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t.Errorf("got %v; want %v", got, tt.want)
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}
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})
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}
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}
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func TestGetRCode(t *testing.T) {
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tests := []struct {
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name string
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packet []byte
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want dns.RCode
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}{
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{
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name: "empty",
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packet: []byte{},
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want: dns.RCode(5),
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},
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{
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name: "too-short",
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packet: []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
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want: dns.RCode(5),
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},
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{
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name: "noerror",
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packet: []byte{0xC4, 0xFE, 0x81, 0xA0, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01},
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want: dns.RCode(0),
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},
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{
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name: "refused",
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packet: []byte{0xee, 0xa1, 0x81, 0x05, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01},
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want: dns.RCode(5),
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},
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{
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name: "nxdomain",
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packet: []byte{0x34, 0xf4, 0x81, 0x83, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x00, 0x01},
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want: dns.RCode(3),
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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got := getRCode(tt.packet)
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if got != tt.want {
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t.Errorf("got %d; want %d", got, tt.want)
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}
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})
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}
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}
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