tailscale/util/deephash/deephash_test.go
Joe Tsai 3f1317e3e5
util/deephash: fix TestArrayAllocs
Unfortunately this test fails on certain architectures.
The problem comes down to inconsistencies in the Go escape analysis
where specific variables are marked as escaping on certain architectures.
The variables escaping to the heap are unfortunately in crypto/sha256,
which makes it impossible to fixthis locally in deephash.

For now, fix the test by compensating for the allocations that
occur from calling sha256.digest.Sum.

See golang/go#48055

Fixes #2727

Signed-off-by: Joe Tsai <joetsai@digital-static.net>
2021-08-30 10:47:21 -07:00

377 lines
10 KiB
Go

// Copyright (c) 2020 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 deephash
import (
"archive/tar"
"bufio"
"bytes"
"crypto/sha256"
"fmt"
"math"
"reflect"
"runtime"
"testing"
"inet.af/netaddr"
"tailscale.com/tailcfg"
"tailscale.com/types/dnstype"
"tailscale.com/types/ipproto"
"tailscale.com/util/dnsname"
"tailscale.com/version"
"tailscale.com/wgengine/filter"
"tailscale.com/wgengine/router"
"tailscale.com/wgengine/wgcfg"
)
type appendBytes []byte
func (p appendBytes) AppendTo(b []byte) []byte {
return append(b, p...)
}
func TestHash(t *testing.T) {
type tuple [2]interface{}
type iface struct{ X interface{} }
type scalars struct {
I8 int8
I16 int16
I32 int32
I64 int64
I int
U8 uint8
U16 uint16
U32 uint32
U64 uint64
U uint
UP uintptr
F32 float32
F64 float64
C64 complex64
C128 complex128
}
type MyBool bool
type MyHeader tar.Header
tests := []struct {
in tuple
wantEq bool
}{
{in: tuple{false, true}, wantEq: false},
{in: tuple{true, true}, wantEq: true},
{in: tuple{false, false}, wantEq: true},
{
in: tuple{
scalars{-8, -16, -32, -64, -1234, 8, 16, 32, 64, 1234, 5678, 32.32, 64.64, 32 + 32i, 64 + 64i},
scalars{-8, -16, -32, -64, -1234, 8, 16, 32, 64, 1234, 5678, 32.32, 64.64, 32 + 32i, 64 + 64i},
},
wantEq: true,
},
{in: tuple{scalars{I8: math.MinInt8}, scalars{I8: math.MinInt8 / 2}}, wantEq: false},
{in: tuple{scalars{I16: math.MinInt16}, scalars{I16: math.MinInt16 / 2}}, wantEq: false},
{in: tuple{scalars{I32: math.MinInt32}, scalars{I32: math.MinInt32 / 2}}, wantEq: false},
{in: tuple{scalars{I64: math.MinInt64}, scalars{I64: math.MinInt64 / 2}}, wantEq: false},
{in: tuple{scalars{I: -1234}, scalars{I: -1234 / 2}}, wantEq: false},
{in: tuple{scalars{U8: math.MaxUint8}, scalars{U8: math.MaxUint8 / 2}}, wantEq: false},
{in: tuple{scalars{U16: math.MaxUint16}, scalars{U16: math.MaxUint16 / 2}}, wantEq: false},
{in: tuple{scalars{U32: math.MaxUint32}, scalars{U32: math.MaxUint32 / 2}}, wantEq: false},
{in: tuple{scalars{U64: math.MaxUint64}, scalars{U64: math.MaxUint64 / 2}}, wantEq: false},
{in: tuple{scalars{U: 1234}, scalars{U: 1234 / 2}}, wantEq: false},
{in: tuple{scalars{UP: 5678}, scalars{UP: 5678 / 2}}, wantEq: false},
{in: tuple{scalars{F32: 32.32}, scalars{F32: math.Nextafter32(32.32, 0)}}, wantEq: false},
{in: tuple{scalars{F64: 64.64}, scalars{F64: math.Nextafter(64.64, 0)}}, wantEq: false},
{in: tuple{scalars{F32: float32(math.NaN())}, scalars{F32: float32(math.NaN())}}, wantEq: true},
{in: tuple{scalars{F64: float64(math.NaN())}, scalars{F64: float64(math.NaN())}}, wantEq: true},
{in: tuple{scalars{C64: 32 + 32i}, scalars{C64: complex(math.Nextafter32(32, 0), 32)}}, wantEq: false},
{in: tuple{scalars{C128: 64 + 64i}, scalars{C128: complex(math.Nextafter(64, 0), 64)}}, wantEq: false},
{in: tuple{[]appendBytes{{}, {0, 0, 0, 0, 0, 0, 0, 1}}, []appendBytes{{}, {0, 0, 0, 0, 0, 0, 0, 1}}}, wantEq: true},
{in: tuple{[]appendBytes{{}, {0, 0, 0, 0, 0, 0, 0, 1}}, []appendBytes{{0, 0, 0, 0, 0, 0, 0, 1}, {}}}, wantEq: false},
{in: tuple{iface{MyBool(true)}, iface{MyBool(true)}}, wantEq: true},
{in: tuple{iface{true}, iface{MyBool(true)}}, wantEq: false},
{in: tuple{iface{MyHeader{}}, iface{MyHeader{}}}, wantEq: true},
{in: tuple{iface{MyHeader{}}, iface{tar.Header{}}}, wantEq: false},
{in: tuple{iface{&MyHeader{}}, iface{&MyHeader{}}}, wantEq: true},
{in: tuple{iface{&MyHeader{}}, iface{&tar.Header{}}}, wantEq: false},
{in: tuple{iface{[]map[string]MyBool{}}, iface{[]map[string]MyBool{}}}, wantEq: true},
{in: tuple{iface{[]map[string]bool{}}, iface{[]map[string]MyBool{}}}, wantEq: false},
{
in: func() tuple {
i1 := 1
i2 := 2
v1 := [3]*int{&i1, &i2, &i1}
v2 := [3]*int{&i1, &i2, &i2}
return tuple{v1, v2}
}(),
wantEq: false,
},
}
for _, tt := range tests {
gotEq := Hash(tt.in[0]) == Hash(tt.in[1])
if gotEq != tt.wantEq {
t.Errorf("(Hash(%v) == Hash(%v)) = %v, want %v", tt.in[0], tt.in[1], gotEq, tt.wantEq)
}
}
}
func TestDeepHash(t *testing.T) {
// v contains the types of values we care about for our current callers.
// Mostly we're just testing that we don't panic on handled types.
v := getVal()
hash1 := Hash(v)
t.Logf("hash: %v", hash1)
for i := 0; i < 20; i++ {
hash2 := Hash(getVal())
if hash1 != hash2 {
t.Error("second hash didn't match")
}
}
}
func getVal() []interface{} {
return []interface{}{
&wgcfg.Config{
Name: "foo",
Addresses: []netaddr.IPPrefix{netaddr.IPPrefixFrom(netaddr.IPFrom16([16]byte{3: 3}), 5)},
Peers: []wgcfg.Peer{
{
Endpoints: wgcfg.Endpoints{
IPPorts: wgcfg.NewIPPortSet(netaddr.MustParseIPPort("42.42.42.42:5")),
},
},
},
},
&router.Config{
Routes: []netaddr.IPPrefix{
netaddr.MustParseIPPrefix("1.2.3.0/24"),
netaddr.MustParseIPPrefix("1234::/64"),
},
},
map[dnsname.FQDN][]netaddr.IP{
dnsname.FQDN("a."): {netaddr.MustParseIP("1.2.3.4"), netaddr.MustParseIP("4.3.2.1")},
dnsname.FQDN("b."): {netaddr.MustParseIP("8.8.8.8"), netaddr.MustParseIP("9.9.9.9")},
dnsname.FQDN("c."): {netaddr.MustParseIP("6.6.6.6"), netaddr.MustParseIP("7.7.7.7")},
dnsname.FQDN("d."): {netaddr.MustParseIP("6.7.6.6"), netaddr.MustParseIP("7.7.7.8")},
dnsname.FQDN("e."): {netaddr.MustParseIP("6.8.6.6"), netaddr.MustParseIP("7.7.7.9")},
dnsname.FQDN("f."): {netaddr.MustParseIP("6.9.6.6"), netaddr.MustParseIP("7.7.7.0")},
},
map[dnsname.FQDN][]netaddr.IPPort{
dnsname.FQDN("a."): {netaddr.MustParseIPPort("1.2.3.4:11"), netaddr.MustParseIPPort("4.3.2.1:22")},
dnsname.FQDN("b."): {netaddr.MustParseIPPort("8.8.8.8:11"), netaddr.MustParseIPPort("9.9.9.9:22")},
dnsname.FQDN("c."): {netaddr.MustParseIPPort("8.8.8.8:12"), netaddr.MustParseIPPort("9.9.9.9:23")},
dnsname.FQDN("d."): {netaddr.MustParseIPPort("8.8.8.8:13"), netaddr.MustParseIPPort("9.9.9.9:24")},
dnsname.FQDN("e."): {netaddr.MustParseIPPort("8.8.8.8:14"), netaddr.MustParseIPPort("9.9.9.9:25")},
},
map[tailcfg.DiscoKey]bool{
{1: 1}: true,
{1: 2}: false,
{2: 3}: true,
{3: 4}: false,
},
&tailcfg.MapResponse{
DERPMap: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
1: &tailcfg.DERPRegion{
RegionID: 1,
RegionCode: "foo",
Nodes: []*tailcfg.DERPNode{
{
Name: "n1",
RegionID: 1,
HostName: "foo.com",
},
{
Name: "n2",
RegionID: 1,
HostName: "bar.com",
},
},
},
},
},
DNSConfig: &tailcfg.DNSConfig{
Resolvers: []dnstype.Resolver{
{Addr: "10.0.0.1"},
},
},
PacketFilter: []tailcfg.FilterRule{
{
SrcIPs: []string{"1.2.3.4"},
DstPorts: []tailcfg.NetPortRange{
{
IP: "1.2.3.4/32",
Ports: tailcfg.PortRange{First: 1, Last: 2},
},
},
},
},
Peers: []*tailcfg.Node{
{
ID: 1,
},
{
ID: 2,
},
},
UserProfiles: []tailcfg.UserProfile{
{ID: 1, LoginName: "foo@bar.com"},
{ID: 2, LoginName: "bar@foo.com"},
},
},
filter.Match{
IPProto: []ipproto.Proto{1, 2, 3},
},
}
}
var sink = Hash("foo")
func BenchmarkHash(b *testing.B) {
b.ReportAllocs()
v := getVal()
for i := 0; i < b.N; i++ {
sink = Hash(v)
}
}
func TestHashMapAcyclic(t *testing.T) {
m := map[int]string{}
for i := 0; i < 100; i++ {
m[i] = fmt.Sprint(i)
}
got := map[string]bool{}
var buf bytes.Buffer
bw := bufio.NewWriter(&buf)
for i := 0; i < 20; i++ {
v := reflect.ValueOf(m)
buf.Reset()
bw.Reset(&buf)
h := &hasher{bw: bw}
h.hashMap(v)
if got[string(buf.Bytes())] {
continue
}
got[string(buf.Bytes())] = true
}
if len(got) != 1 {
t.Errorf("got %d results; want 1", len(got))
}
}
func TestPrintArray(t *testing.T) {
type T struct {
X [32]byte
}
x := T{X: [32]byte{1: 1, 31: 31}}
var got bytes.Buffer
bw := bufio.NewWriter(&got)
h := &hasher{bw: bw}
h.hashValue(reflect.ValueOf(x))
bw.Flush()
const want = "\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x1f"
if got := got.Bytes(); string(got) != want {
t.Errorf("wrong:\n got: %q\nwant: %q\n", got, want)
}
}
func BenchmarkHashMapAcyclic(b *testing.B) {
b.ReportAllocs()
m := map[int]string{}
for i := 0; i < 100; i++ {
m[i] = fmt.Sprint(i)
}
var buf bytes.Buffer
bw := bufio.NewWriter(&buf)
v := reflect.ValueOf(m)
h := &hasher{bw: bw}
for i := 0; i < b.N; i++ {
buf.Reset()
bw.Reset(&buf)
h.hashMap(v)
}
}
func BenchmarkTailcfgNode(b *testing.B) {
b.ReportAllocs()
node := new(tailcfg.Node)
for i := 0; i < b.N; i++ {
sink = Hash(node)
}
}
func TestExhaustive(t *testing.T) {
seen := make(map[Sum]bool)
for i := 0; i < 100000; i++ {
s := Hash(i)
if seen[s] {
t.Fatalf("hash collision %v", i)
}
seen[s] = true
}
}
// verify this doesn't loop forever, as it used to (Issue 2340)
func TestMapCyclicFallback(t *testing.T) {
type T struct {
M map[string]interface{}
}
v := &T{
M: map[string]interface{}{},
}
v.M["m"] = v.M
Hash(v)
}
func TestArrayAllocs(t *testing.T) {
if version.IsRace() {
t.Skip("skipping test under race detector")
}
// In theory, there should be no allocations. However, escape analysis on
// certain architectures fails to detect that certain cases do not escape.
// This discrepency currently affects sha256.digest.Sum.
// Measure the number of allocations in sha256 to ensure that Hash does
// not allocate on top of its usage of sha256.
// See https://golang.org/issue/48055.
var b []byte
h := sha256.New()
want := int(testing.AllocsPerRun(1000, func() {
b = h.Sum(b[:0])
}))
switch runtime.GOARCH {
case "amd64", "arm64":
want = 0 // ensure no allocations on popular architectures
}
type T struct {
X [32]byte
}
x := &T{X: [32]byte{1: 1, 2: 2, 3: 3, 4: 4}}
got := int(testing.AllocsPerRun(1000, func() {
sink = Hash(x)
}))
if got > want {
t.Errorf("allocs = %v; want %v", got, want)
}
}
func BenchmarkHashArray(b *testing.B) {
b.ReportAllocs()
type T struct {
X [32]byte
}
x := &T{X: [32]byte{1: 1, 2: 2, 3: 3, 4: 4}}
for i := 0; i < b.N; i++ {
sink = Hash(x)
}
}