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tailscale/util/deephash/deephash_test.go

1053 lines
34 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"
"crypto/sha256"
"encoding/binary"
"fmt"
"hash"
"math"
"math/bits"
"math/rand"
"net/netip"
"reflect"
"runtime"
"testing"
"testing/quick"
"time"
qt "github.com/frankban/quicktest"
"go4.org/mem"
"go4.org/netipx"
"tailscale.com/tailcfg"
"tailscale.com/types/dnstype"
"tailscale.com/types/ipproto"
"tailscale.com/types/key"
"tailscale.com/util/deephash/testtype"
"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]any
type iface struct{ X any }
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
var zeroFloat64 float64
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{[]int(nil), []int(nil)}, wantEq: true},
{in: tuple{[]int{}, []int(nil)}, wantEq: false},
{in: tuple{[]int{}, []int{}}, wantEq: true},
{in: tuple{[]string(nil), []string(nil)}, wantEq: true},
{in: tuple{[]string{}, []string(nil)}, wantEq: false},
{in: tuple{[]string{}, []string{}}, wantEq: true},
{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: tuple{zeroFloat64, -zeroFloat64}, wantEq: false}, // Issue 4883 (false alarm)
{in: tuple{[]any(nil), 0.0}, wantEq: false}, // Issue 4883
{in: tuple{[]any(nil), uint8(0)}, wantEq: false}, // Issue 4883
{in: tuple{nil, nil}, wantEq: true}, // Issue 4883
util/deephash: improve cycle detection (#2470) The previous algorithm used a map of all visited pointers. The strength of this approach is that it quickly prunes any nodes that we have ever visited before. The detriment of the approach is that pruning is heavily dependent on the order that pointers were visited. This is especially relevant for hashing a map where map entries are visited in a non-deterministic manner, which would cause the map hash to be non-deterministic (which defeats the point of a hash). This new algorithm uses a stack of all visited pointers, similar to how github.com/google/go-cmp performs cycle detection. When we visit a pointer, we push it onto the stack, and when we leave a pointer, we pop it from the stack. Before visiting a pointer, we first check whether the pointer exists anywhere in the stack. If yes, then we prune the node. The detriment of this approach is that we may hash a node more often than before since we do not prune as aggressively. The set of visited pointers up until any node is only the path of nodes up to that node and not any other pointers that may have been visited elsewhere. This provides us deterministic hashing regardless of visit order. We can now delete hashMapFallback and associated complexity, which only exists because the previous approach was non-deterministic in the presence of cycles. This fixes a failure of the old algorithm where obviously different values are treated as equal because the pruning was too aggresive. See https://github.com/tailscale/tailscale/issues/2443#issuecomment-883653534 The new algorithm is slightly slower since it prunes less aggresively: name old time/op new time/op delta Hash-8 66.1µs ± 1% 68.8µs ± 1% +4.09% (p=0.000 n=19+19) HashMapAcyclic-8 63.0µs ± 1% 62.5µs ± 1% -0.76% (p=0.000 n=18+19) TailcfgNode-8 9.79µs ± 2% 9.88µs ± 1% +0.95% (p=0.000 n=19+17) HashArray-8 643ns ± 1% 653ns ± 1% +1.64% (p=0.000 n=19+19) However, a slower but more correct algorithm seems more favorable than a faster but incorrect algorithm. Signed-off-by: Joe Tsai <joetsai@digital-static.net>
3 years ago
{
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,
},
{in: tuple{netip.Addr{}, netip.Addr{}}, wantEq: true},
{in: tuple{netip.Addr{}, netip.AddrFrom4([4]byte{})}, wantEq: false},
{in: tuple{netip.AddrFrom4([4]byte{}), netip.AddrFrom4([4]byte{})}, wantEq: true},
{in: tuple{netip.AddrFrom4([4]byte{192, 168, 0, 1}), netip.AddrFrom4([4]byte{192, 168, 0, 1})}, wantEq: true},
{in: tuple{netip.AddrFrom4([4]byte{192, 168, 0, 1}), netip.AddrFrom4([4]byte{192, 168, 0, 2})}, wantEq: false},
{in: tuple{netip.AddrFrom4([4]byte{}), netip.AddrFrom16([16]byte{})}, wantEq: false},
{in: tuple{netip.AddrFrom16([16]byte{}), netip.AddrFrom16([16]byte{})}, wantEq: true},
{in: tuple{netip.AddrPort{}, netip.AddrPort{}}, wantEq: true},
{in: tuple{netip.AddrPort{}, netip.AddrPortFrom(netip.AddrFrom4([4]byte{}), 0)}, wantEq: false},
{in: tuple{netip.AddrPortFrom(netip.AddrFrom4([4]byte{}), 0), netip.AddrPortFrom(netip.AddrFrom4([4]byte{}), 0)}, wantEq: true},
{in: tuple{netip.AddrPortFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), 1234), netip.AddrPortFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), 1234)}, wantEq: true},
{in: tuple{netip.AddrPortFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), 1234), netip.AddrPortFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), 1235)}, wantEq: false},
{in: tuple{netip.AddrPortFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), 1234), netip.AddrPortFrom(netip.AddrFrom4([4]byte{192, 168, 0, 2}), 1234)}, wantEq: false},
{in: tuple{netip.Prefix{}, netip.Prefix{}}, wantEq: true},
{in: tuple{netip.Prefix{}, netip.PrefixFrom(netip.Addr{}, 1)}, wantEq: false},
{in: tuple{netip.Prefix{}, netip.PrefixFrom(netip.AddrFrom4([4]byte{}), 0)}, wantEq: false},
{in: tuple{netip.PrefixFrom(netip.AddrFrom4([4]byte{}), 1), netip.PrefixFrom(netip.AddrFrom4([4]byte{}), 1)}, wantEq: true},
{in: tuple{netip.PrefixFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), 1), netip.PrefixFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), 1)}, wantEq: true},
{in: tuple{netip.PrefixFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), 1), netip.PrefixFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), 0)}, wantEq: false},
{in: tuple{netip.PrefixFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), 1), netip.PrefixFrom(netip.AddrFrom4([4]byte{192, 168, 0, 2}), 1)}, wantEq: false},
{in: tuple{netipx.IPRange{}, netipx.IPRange{}}, wantEq: true},
{in: tuple{netipx.IPRange{}, netipx.IPRangeFrom(netip.AddrFrom4([4]byte{}), netip.AddrFrom16([16]byte{}))}, wantEq: false},
{in: tuple{netipx.IPRangeFrom(netip.AddrFrom4([4]byte{}), netip.AddrFrom16([16]byte{})), netipx.IPRangeFrom(netip.AddrFrom4([4]byte{}), netip.AddrFrom16([16]byte{}))}, wantEq: true},
{in: tuple{netipx.IPRangeFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), netip.AddrFrom4([4]byte{192, 168, 0, 100})), netipx.IPRangeFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), netip.AddrFrom4([4]byte{192, 168, 0, 100}))}, wantEq: true},
{in: tuple{netipx.IPRangeFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), netip.AddrFrom4([4]byte{192, 168, 0, 100})), netipx.IPRangeFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), netip.AddrFrom4([4]byte{192, 168, 0, 101}))}, wantEq: false},
{in: tuple{netipx.IPRangeFrom(netip.AddrFrom4([4]byte{192, 168, 0, 1}), netip.AddrFrom4([4]byte{192, 168, 0, 100})), netipx.IPRangeFrom(netip.AddrFrom4([4]byte{192, 168, 0, 2}), netip.AddrFrom4([4]byte{192, 168, 0, 100}))}, wantEq: false},
{in: tuple{key.DiscoPublic{}, key.DiscoPublic{}}, wantEq: true},
{in: tuple{key.DiscoPublic{}, key.DiscoPublicFromRaw32(mem.B(func() []byte {
b := make([]byte, 32)
b[0] = 1
return b
}()))}, wantEq: false},
{in: tuple{key.NodePublic{}, key.NodePublic{}}, wantEq: true},
{in: tuple{key.NodePublic{}, key.NodePublicFromRaw32(mem.B(func() []byte {
b := make([]byte, 32)
b[0] = 1
return b
}()))}, wantEq: false},
}
for _, tt := range tests {
gotEq := Hash(&tt.in[0]) == Hash(&tt.in[1])
if gotEq != tt.wantEq {
t.Errorf("(Hash(%T %v) == Hash(%T %v)) = %v, want %v", tt.in[0], tt.in[0], tt.in[1], 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++ {
v := getVal()
hash2 := Hash(v)
if hash1 != hash2 {
t.Error("second hash didn't match")
}
}
}
// Tests that we actually hash map elements. Whoops.
func TestIssue4868(t *testing.T) {
m1 := map[int]string{1: "foo"}
m2 := map[int]string{1: "bar"}
if Hash(&m1) == Hash(&m2) {
t.Error("bogus")
}
}
func TestIssue4871(t *testing.T) {
m1 := map[string]string{"": "", "x": "foo"}
m2 := map[string]string{}
if h1, h2 := Hash(&m1), Hash(&m2); h1 == h2 {
t.Errorf("bogus: h1=%x, h2=%x", h1, h2)
}
}
func TestNilVsEmptymap(t *testing.T) {
m1 := map[string]string(nil)
m2 := map[string]string{}
if h1, h2 := Hash(&m1), Hash(&m2); h1 == h2 {
t.Errorf("bogus: h1=%x, h2=%x", h1, h2)
}
}
func TestMapFraming(t *testing.T) {
m1 := map[string]string{"foo": "", "fo": "o"}
m2 := map[string]string{}
if h1, h2 := Hash(&m1), Hash(&m2); h1 == h2 {
t.Errorf("bogus: h1=%x, h2=%x", h1, h2)
}
}
func TestQuick(t *testing.T) {
initSeed()
err := quick.Check(func(v, w map[string]string) bool {
return (Hash(&v) == Hash(&w)) == reflect.DeepEqual(v, w)
}, &quick.Config{MaxCount: 1000, Rand: rand.New(rand.NewSource(int64(seed)))})
if err != nil {
t.Fatalf("seed=%v, err=%v", seed, err)
}
}
type tailscaleTypes struct {
WGConfig *wgcfg.Config
RouterConfig *router.Config
MapFQDNAddrs map[dnsname.FQDN][]netip.Addr
MapFQDNAddrPorts map[dnsname.FQDN][]netip.AddrPort
MapDiscoPublics map[key.DiscoPublic]bool
MapResponse *tailcfg.MapResponse
FilterMatch filter.Match
}
func getVal() *tailscaleTypes {
return &tailscaleTypes{
&wgcfg.Config{
Name: "foo",
Addresses: []netip.Prefix{netip.PrefixFrom(netip.AddrFrom16([16]byte{3: 3}).Unmap(), 5)},
Peers: []wgcfg.Peer{
{
PublicKey: key.NodePublic{},
},
},
},
&router.Config{
Routes: []netip.Prefix{
netip.MustParsePrefix("1.2.3.0/24"),
netip.MustParsePrefix("1234::/64"),
},
},
map[dnsname.FQDN][]netip.Addr{
dnsname.FQDN("a."): {netip.MustParseAddr("1.2.3.4"), netip.MustParseAddr("4.3.2.1")},
dnsname.FQDN("b."): {netip.MustParseAddr("8.8.8.8"), netip.MustParseAddr("9.9.9.9")},
dnsname.FQDN("c."): {netip.MustParseAddr("6.6.6.6"), netip.MustParseAddr("7.7.7.7")},
dnsname.FQDN("d."): {netip.MustParseAddr("6.7.6.6"), netip.MustParseAddr("7.7.7.8")},
dnsname.FQDN("e."): {netip.MustParseAddr("6.8.6.6"), netip.MustParseAddr("7.7.7.9")},
dnsname.FQDN("f."): {netip.MustParseAddr("6.9.6.6"), netip.MustParseAddr("7.7.7.0")},
},
map[dnsname.FQDN][]netip.AddrPort{
dnsname.FQDN("a."): {netip.MustParseAddrPort("1.2.3.4:11"), netip.MustParseAddrPort("4.3.2.1:22")},
dnsname.FQDN("b."): {netip.MustParseAddrPort("8.8.8.8:11"), netip.MustParseAddrPort("9.9.9.9:22")},
dnsname.FQDN("c."): {netip.MustParseAddrPort("8.8.8.8:12"), netip.MustParseAddrPort("9.9.9.9:23")},
dnsname.FQDN("d."): {netip.MustParseAddrPort("8.8.8.8:13"), netip.MustParseAddrPort("9.9.9.9:24")},
dnsname.FQDN("e."): {netip.MustParseAddrPort("8.8.8.8:14"), netip.MustParseAddrPort("9.9.9.9:25")},
},
map[key.DiscoPublic]bool{
key.DiscoPublicFromRaw32(mem.B([]byte{1: 1, 31: 0})): true,
key.DiscoPublicFromRaw32(mem.B([]byte{1: 2, 31: 0})): false,
key.DiscoPublicFromRaw32(mem.B([]byte{1: 3, 31: 0})): true,
key.DiscoPublicFromRaw32(mem.B([]byte{1: 4, 31: 0})): false,
},
&tailcfg.MapResponse{
DERPMap: &tailcfg.DERPMap{
Regions: map[int]*tailcfg.DERPRegion{
1: {
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},
},
}
}
type IntThenByte struct {
i int
b byte
}
type TwoInts struct{ a, b int }
type IntIntByteInt struct {
i1, i2 int32
b byte // padding after
i3 int32
}
func u8(n uint8) string { return string([]byte{n}) }
func u16(n uint16) string { return string(binary.LittleEndian.AppendUint16(nil, n)) }
func u32(n uint32) string { return string(binary.LittleEndian.AppendUint32(nil, n)) }
func u64(n uint64) string { return string(binary.LittleEndian.AppendUint64(nil, n)) }
func ux(n uint) string {
if bits.UintSize == 32 {
return u32(uint32(n))
} else {
return u64(uint64(n))
}
}
func TestGetTypeHasher(t *testing.T) {
switch runtime.GOARCH {
case "amd64", "arm64", "arm", "386", "riscv64":
default:
// Test outputs below are specifically for little-endian machines.
// Just skip everything else for now. Feel free to add more above if
// you have the hardware to test and it's little-endian.
t.Skipf("skipping on %v", runtime.GOARCH)
}
type typedString string
var (
someInt = int('A')
someComplex128 = complex128(1 + 2i)
someIP = netip.MustParseAddr("1.2.3.4")
)
tests := []struct {
name string
val any
out string
out32 string // overwrites out if 32-bit
}{
{
name: "int",
val: int(1),
out: ux(1),
},
{
name: "int_negative",
val: int(-1),
out: ux(math.MaxUint),
},
{
name: "int8",
val: int8(1),
out: "\x01",
},
{
name: "float64",
val: float64(1.0),
out: "\x00\x00\x00\x00\x00\x00\xf0?",
},
{
name: "float32",
val: float32(1.0),
out: "\x00\x00\x80?",
},
{
name: "string",
val: "foo",
out: "\x03\x00\x00\x00\x00\x00\x00\x00foo",
},
{
name: "typedString",
val: typedString("foo"),
out: "\x03\x00\x00\x00\x00\x00\x00\x00foo",
},
{
name: "string_slice",
val: []string{"foo", "bar"},
out: "\x01\x02\x00\x00\x00\x00\x00\x00\x00\x03\x00\x00\x00\x00\x00\x00\x00foo\x03\x00\x00\x00\x00\x00\x00\x00bar",
},
{
name: "int_slice",
val: []int{1, 0, -1},
out: "\x01\x03\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff",
out32: "\x01\x03\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff",
},
{
name: "struct",
val: struct {
a, b int
c uint16
}{1, -1, 2},
util/deephash: always keep values addressable (#5328) The logic of deephash is both simpler and easier to reason about if values are always addressable. In Go, the composite kinds are slices, arrays, maps, structs, interfaces, pointers, channels, and functions, where we define "composite" as a Go value that encapsulates some other Go value (e.g., a map is a collection of key-value entries). In the cases of pointers and slices, the sub-values are always addressable. In the cases of arrays and structs, the sub-values are always addressable if and only if the parent value is addressable. In the case of maps and interfaces, the sub-values are never addressable. To make them addressable, we need to copy them onto the heap. For the purposes of deephash, we do not care about channels and functions. For all non-composite kinds (e.g., strings and ints), they are only addressable if obtained from one of the composite kinds that produce addressable values (i.e., pointers, slices, addressable arrays, and addressable structs). A non-addressible, non-composite kind can be made addressable by allocating it on the heap, obtaining a pointer to it, and dereferencing it. Thus, if we can ensure that values are addressable at the entry points, and shallow copy sub-values whenever we encounter an interface or map, then we can ensure that all values are always addressable and assume such property throughout all the logic. Performance: name old time/op new time/op delta Hash-24 21.5µs ± 1% 19.7µs ± 1% -8.29% (p=0.000 n=9+9) HashPacketFilter-24 2.61µs ± 1% 2.62µs ± 0% +0.29% (p=0.037 n=10+9) HashMapAcyclic-24 30.8µs ± 1% 30.9µs ± 1% ~ (p=0.400 n=9+10) TailcfgNode-24 1.84µs ± 1% 1.84µs ± 2% ~ (p=0.928 n=10+10) HashArray-24 324ns ± 2% 332ns ± 2% +2.45% (p=0.000 n=10+10) Signed-off-by: Joe Tsai <joetsai@digital-static.net>
2 years ago
out: "\x01\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\x02\x00",
out32: "\x01\x00\x00\x00\xff\xff\xff\xff\x02\x00",
},
{
name: "nil_int_ptr",
val: (*int)(nil),
out: "\x00",
},
{
name: "int_ptr",
val: &someInt,
out: "\x01A\x00\x00\x00\x00\x00\x00\x00",
out32: "\x01A\x00\x00\x00",
},
{
name: "nil_uint32_ptr",
val: (*uint32)(nil),
out: "\x00",
},
{
name: "complex128_ptr",
val: &someComplex128,
out: "\x01\x00\x00\x00\x00\x00\x00\xf0?\x00\x00\x00\x00\x00\x00\x00@",
},
{
name: "packet_filter",
val: filterRules,
out: "\x01\x04\x00\x00\x00\x00\x00\x00\x00\x01\x03\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00*\v\x00\x00\x00\x00\x00\x00\x0010.1.3.4/32\v\x00\x00\x00\x00\x00\x00\x0010.0.0.0/24\x01\x03\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00\x03\x00\x00\x00\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\n\x00\x00\x00\x00\x00\x00\x001.2.3.4/32\x01 \x00\x00\x00\x00\x00\x00\x00\x01\x00\x02\x00\x01\x04\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00\x03\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x01\x02\x03\x04 \x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\x03\x00\x00\x00\x00\x00\x00\x00foo\x01\x01\x00\x00\x00\x00\x00\x00\x00\v\x00\x00\x00\x00\x00\x00\x00foooooooooo\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\f\x00\x00\x00\x00\x00\x00\x00baaaaaarrrrr\x00\x01\x00\x02\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\v\x00\x00\x00\x00\x00\x00\x00foooooooooo\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\f\x00\x00\x00\x00\x00\x00\x00baaaaaarrrrr\x00\x01\x00\x02\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\v\x00\x00\x00\x00\x00\x00\x00foooooooooo\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\f\x00\x00\x00\x00\x00\x00\x00baaaaaarrrrr\x00\x01\x00\x02\x00\x00\x00",
out32: "\x01\x04\x00\x00\x00\x00\x00\x00\x00\x01\x03\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00*\v\x00\x00\x00\x00\x00\x00\x0010.1.3.4/32\v\x00\x00\x00\x00\x00\x00\x0010.0.0.0/24\x01\x03\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x02\x00\x00\x00\x03\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\n\x00\x00\x00\x00\x00\x00\x001.2.3.4/32\x01 \x00\x00\x00\x01\x00\x02\x00\x01\x04\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x02\x00\x00\x00\x03\x00\x00\x00\x04\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x01\x02\x03\x04 \x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\x03\x00\x00\x00\x00\x00\x00\x00foo\x01\x01\x00\x00\x00\x00\x00\x00\x00\v\x00\x00\x00\x00\x00\x00\x00foooooooooo\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\f\x00\x00\x00\x00\x00\x00\x00baaaaaarrrrr\x00\x01\x00\x02\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\v\x00\x00\x00\x00\x00\x00\x00foooooooooo\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\f\x00\x00\x00\x00\x00\x00\x00baaaaaarrrrr\x00\x01\x00\x02\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\v\x00\x00\x00\x00\x00\x00\x00foooooooooo\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\f\x00\x00\x00\x00\x00\x00\x00baaaaaarrrrr\x00\x01\x00\x02\x00\x00\x00",
},
{
name: "netip.Addr",
val: netip.MustParseAddr("fe80::123%foo"),
out: u64(16+3) + u64(0x80fe) + u64(0x2301<<48) + "foo",
},
{
name: "ptr-netip.Addr",
val: &someIP,
out: u8(1) + u64(4) + u32(0x04030201),
},
{
name: "ptr-nil-netip.Addr",
val: (*netip.Addr)(nil),
out: "\x00",
},
{
name: "time",
val: time.Unix(1234, 5678).In(time.UTC),
out: u64(1234) + u32(5678) + u32(0),
},
{
name: "time_ptr", // addressable, as opposed to "time" test above
val: ptrTo(time.Unix(1234, 5678).In(time.UTC)),
out: u8(1) + u64(1234) + u32(5678) + u32(0),
},
{
name: "time_ptr_via_unexported",
val: testtype.NewUnexportedAddressableTime(time.Unix(1234, 5678).In(time.UTC)),
out: u8(1) + u64(1234) + u32(5678) + u32(0),
},
{
name: "time_ptr_via_unexported_value",
val: *testtype.NewUnexportedAddressableTime(time.Unix(1234, 5678).In(time.UTC)),
out: u64(1234) + u32(5678) + u32(0),
},
{
name: "time_custom_zone",
val: time.Unix(1655311822, 0).In(time.FixedZone("FOO", -60*60)),
out: u64(1655311822) + u32(0) + u32(math.MaxUint32-60*60+1),
},
{
name: "time_nil",
val: (*time.Time)(nil),
out: "\x00",
},
{
name: "array_memhash",
val: [4]byte{1, 2, 3, 4},
out: "\x01\x02\x03\x04",
},
{
name: "array_ptr_memhash",
val: ptrTo([4]byte{1, 2, 3, 4}),
out: "\x01\x01\x02\x03\x04",
},
{
name: "ptr_to_struct_partially_memhashable",
val: &struct {
A int16
B int16
C *int
}{5, 6, nil},
out: "\x01\x05\x00\x06\x00\x00",
},
{
name: "struct_partially_memhashable_but_cant_addr",
val: struct {
A int16
B int16
C *int
}{5, 6, nil},
out: "\x05\x00\x06\x00\x00",
},
{
name: "array_elements",
val: [4]byte{1, 2, 3, 4},
out: "\x01\x02\x03\x04",
},
{
name: "bool",
val: true,
out: "\x01",
},
{
name: "IntIntByteInt",
val: IntIntByteInt{1, 2, 3, 4},
out: "\x01\x00\x00\x00\x02\x00\x00\x00\x03\x04\x00\x00\x00",
},
{
name: "IntIntByteInt-canddr",
val: &IntIntByteInt{1, 2, 3, 4},
out: "\x01\x01\x00\x00\x00\x02\x00\x00\x00\x03\x04\x00\x00\x00",
},
{
name: "array-IntIntByteInt",
val: [2]IntIntByteInt{
{1, 2, 3, 4},
{5, 6, 7, 8},
},
out: "\x01\x00\x00\x00\x02\x00\x00\x00\x03\x04\x00\x00\x00\x05\x00\x00\x00\x06\x00\x00\x00\a\b\x00\x00\x00",
},
{
name: "array-IntIntByteInt-canaddr",
val: &[2]IntIntByteInt{
{1, 2, 3, 4},
{5, 6, 7, 8},
},
out: "\x01\x01\x00\x00\x00\x02\x00\x00\x00\x03\x04\x00\x00\x00\x05\x00\x00\x00\x06\x00\x00\x00\a\b\x00\x00\x00",
},
{
name: "tailcfg.Node",
val: &tailcfg.Node{},
out: "\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\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\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\tn\x88\xf1\xff\xff\xff\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\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\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\tn\x88\xf1\xff\xff\xff\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\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
rv := reflect.ValueOf(tt.val)
va := reflect.New(rv.Type()).Elem()
util/deephash: always keep values addressable (#5328) The logic of deephash is both simpler and easier to reason about if values are always addressable. In Go, the composite kinds are slices, arrays, maps, structs, interfaces, pointers, channels, and functions, where we define "composite" as a Go value that encapsulates some other Go value (e.g., a map is a collection of key-value entries). In the cases of pointers and slices, the sub-values are always addressable. In the cases of arrays and structs, the sub-values are always addressable if and only if the parent value is addressable. In the case of maps and interfaces, the sub-values are never addressable. To make them addressable, we need to copy them onto the heap. For the purposes of deephash, we do not care about channels and functions. For all non-composite kinds (e.g., strings and ints), they are only addressable if obtained from one of the composite kinds that produce addressable values (i.e., pointers, slices, addressable arrays, and addressable structs). A non-addressible, non-composite kind can be made addressable by allocating it on the heap, obtaining a pointer to it, and dereferencing it. Thus, if we can ensure that values are addressable at the entry points, and shallow copy sub-values whenever we encounter an interface or map, then we can ensure that all values are always addressable and assume such property throughout all the logic. Performance: name old time/op new time/op delta Hash-24 21.5µs ± 1% 19.7µs ± 1% -8.29% (p=0.000 n=9+9) HashPacketFilter-24 2.61µs ± 1% 2.62µs ± 0% +0.29% (p=0.037 n=10+9) HashMapAcyclic-24 30.8µs ± 1% 30.9µs ± 1% ~ (p=0.400 n=9+10) TailcfgNode-24 1.84µs ± 1% 1.84µs ± 2% ~ (p=0.928 n=10+10) HashArray-24 324ns ± 2% 332ns ± 2% +2.45% (p=0.000 n=10+10) Signed-off-by: Joe Tsai <joetsai@digital-static.net>
2 years ago
va.Set(rv)
fn := lookupTypeHasher(va.Type())
hb := &hashBuffer{Hash: sha256.New()}
h := new(hasher)
h.Block512.Hash = hb
fn(h, pointerOf(va.Addr()))
const ptrSize = 32 << uintptr(^uintptr(0)>>63)
if tt.out32 != "" && ptrSize == 32 {
tt.out = tt.out32
}
h.sum()
if got := string(hb.B); got != tt.out {
t.Fatalf("got %q; want %q", got, tt.out)
}
})
}
}
func TestSliceCycle(t *testing.T) {
type S []S
c := qt.New(t)
a := make(S, 1) // cylic graph of 1 node
a[0] = a
b := make(S, 1) // cylic graph of 1 node
b[0] = b
ha := Hash(&a)
hb := Hash(&b)
c.Assert(ha, qt.Equals, hb)
c1 := make(S, 1) // cyclic graph of 2 nodes
c2 := make(S, 1) // cyclic graph of 2 nodes
c1[0] = c2
c2[0] = c1
hc1 := Hash(&c1)
hc2 := Hash(&c2)
c.Assert(hc1, qt.Equals, hc2)
c.Assert(ha, qt.Not(qt.Equals), hc1)
c.Assert(hb, qt.Not(qt.Equals), hc2)
c3 := make(S, 1) // graph of 1 node pointing to cyclic graph of 2 nodes
c3[0] = c1
hc3 := Hash(&c3)
c.Assert(hc1, qt.Not(qt.Equals), hc3)
c4 := make(S, 2) // cyclic graph of 3 nodes
c5 := make(S, 2) // cyclic graph of 3 nodes
c4[0] = nil
c4[1] = c4
c5[0] = c5
c5[1] = nil
hc4 := Hash(&c4)
hc5 := Hash(&c5)
c.Assert(hc4, qt.Not(qt.Equals), hc5) // cycle occurs through different indexes
}
func TestMapCycle(t *testing.T) {
type M map[string]M
c := qt.New(t)
a := make(M) // cylic graph of 1 node
a["self"] = a
b := make(M) // cylic graph of 1 node
b["self"] = b
ha := Hash(&a)
hb := Hash(&b)
c.Assert(ha, qt.Equals, hb)
c1 := make(M) // cyclic graph of 2 nodes
c2 := make(M) // cyclic graph of 2 nodes
c1["peer"] = c2
c2["peer"] = c1
hc1 := Hash(&c1)
hc2 := Hash(&c2)
c.Assert(hc1, qt.Equals, hc2)
c.Assert(ha, qt.Not(qt.Equals), hc1)
c.Assert(hb, qt.Not(qt.Equals), hc2)
c3 := make(M) // graph of 1 node pointing to cyclic graph of 2 nodes
c3["child"] = c1
hc3 := Hash(&c3)
c.Assert(hc1, qt.Not(qt.Equals), hc3)
c4 := make(M) // cyclic graph of 3 nodes
c5 := make(M) // cyclic graph of 3 nodes
c4["0"] = nil
c4["1"] = c4
c5["0"] = c5
c5["1"] = nil
hc4 := Hash(&c4)
hc5 := Hash(&c5)
c.Assert(hc4, qt.Not(qt.Equals), hc5) // cycle occurs through different keys
}
func TestPointerCycle(t *testing.T) {
type P *P
c := qt.New(t)
a := new(P) // cyclic graph of 1 node
*a = a
b := new(P) // cyclic graph of 1 node
*b = b
ha := Hash(&a)
hb := Hash(&b)
c.Assert(ha, qt.Equals, hb)
c1 := new(P) // cyclic graph of 2 nodes
c2 := new(P) // cyclic graph of 2 nodes
*c1 = c2
*c2 = c1
hc1 := Hash(&c1)
hc2 := Hash(&c2)
c.Assert(hc1, qt.Equals, hc2)
c.Assert(ha, qt.Not(qt.Equals), hc1)
c.Assert(hb, qt.Not(qt.Equals), hc2)
c3 := new(P) // graph of 1 node pointing to cyclic graph of 2 nodes
*c3 = c1
hc3 := Hash(&c3)
c.Assert(hc1, qt.Not(qt.Equals), hc3)
}
func TestInterfaceCycle(t *testing.T) {
type I struct{ v any }
c := qt.New(t)
a := new(I) // cyclic graph of 1 node
a.v = a
b := new(I) // cyclic graph of 1 node
b.v = b
ha := Hash(&a)
hb := Hash(&b)
c.Assert(ha, qt.Equals, hb)
c1 := new(I) // cyclic graph of 2 nodes
c2 := new(I) // cyclic graph of 2 nodes
c1.v = c2
c2.v = c1
hc1 := Hash(&c1)
hc2 := Hash(&c2)
c.Assert(hc1, qt.Equals, hc2)
c.Assert(ha, qt.Not(qt.Equals), hc1)
c.Assert(hb, qt.Not(qt.Equals), hc2)
c3 := new(I) // graph of 1 node pointing to cyclic graph of 2 nodes
c3.v = c1
hc3 := Hash(&c3)
c.Assert(hc1, qt.Not(qt.Equals), hc3)
}
util/deephash: always keep values addressable (#5328) The logic of deephash is both simpler and easier to reason about if values are always addressable. In Go, the composite kinds are slices, arrays, maps, structs, interfaces, pointers, channels, and functions, where we define "composite" as a Go value that encapsulates some other Go value (e.g., a map is a collection of key-value entries). In the cases of pointers and slices, the sub-values are always addressable. In the cases of arrays and structs, the sub-values are always addressable if and only if the parent value is addressable. In the case of maps and interfaces, the sub-values are never addressable. To make them addressable, we need to copy them onto the heap. For the purposes of deephash, we do not care about channels and functions. For all non-composite kinds (e.g., strings and ints), they are only addressable if obtained from one of the composite kinds that produce addressable values (i.e., pointers, slices, addressable arrays, and addressable structs). A non-addressible, non-composite kind can be made addressable by allocating it on the heap, obtaining a pointer to it, and dereferencing it. Thus, if we can ensure that values are addressable at the entry points, and shallow copy sub-values whenever we encounter an interface or map, then we can ensure that all values are always addressable and assume such property throughout all the logic. Performance: name old time/op new time/op delta Hash-24 21.5µs ± 1% 19.7µs ± 1% -8.29% (p=0.000 n=9+9) HashPacketFilter-24 2.61µs ± 1% 2.62µs ± 0% +0.29% (p=0.037 n=10+9) HashMapAcyclic-24 30.8µs ± 1% 30.9µs ± 1% ~ (p=0.400 n=9+10) TailcfgNode-24 1.84µs ± 1% 1.84µs ± 2% ~ (p=0.928 n=10+10) HashArray-24 324ns ± 2% 332ns ± 2% +2.45% (p=0.000 n=10+10) Signed-off-by: Joe Tsai <joetsai@digital-static.net>
2 years ago
var sink Sum
func BenchmarkHash(b *testing.B) {
b.ReportAllocs()
v := getVal()
for i := 0; i < b.N; i++ {
sink = Hash(v)
}
}
func ptrTo[T any](v T) *T { return &v }
// filterRules is a packet filter that has both everything populated (in its
// first element) and also a few entries that are the typical shape for regular
// packet filters as sent to clients.
var filterRules = []tailcfg.FilterRule{
{
SrcIPs: []string{"*", "10.1.3.4/32", "10.0.0.0/24"},
SrcBits: []int{1, 2, 3},
DstPorts: []tailcfg.NetPortRange{{
IP: "1.2.3.4/32",
Bits: ptrTo(32),
Ports: tailcfg.PortRange{First: 1, Last: 2},
}},
IPProto: []int{1, 2, 3, 4},
CapGrant: []tailcfg.CapGrant{{
Dsts: []netip.Prefix{netip.MustParsePrefix("1.2.3.4/32")},
Caps: []string{"foo"},
}},
},
{
SrcIPs: []string{"foooooooooo"},
DstPorts: []tailcfg.NetPortRange{{
IP: "baaaaaarrrrr",
Ports: tailcfg.PortRange{First: 1, Last: 2},
}},
},
{
SrcIPs: []string{"foooooooooo"},
DstPorts: []tailcfg.NetPortRange{{
IP: "baaaaaarrrrr",
Ports: tailcfg.PortRange{First: 1, Last: 2},
}},
},
{
SrcIPs: []string{"foooooooooo"},
DstPorts: []tailcfg.NetPortRange{{
IP: "baaaaaarrrrr",
Ports: tailcfg.PortRange{First: 1, Last: 2},
}},
},
}
func BenchmarkHashPacketFilter(b *testing.B) {
b.ReportAllocs()
for i := 0; i < b.N; i++ {
sink = Hash(&filterRules)
}
}
func TestHashMapAcyclic(t *testing.T) {
m := map[int]string{}
for i := 0; i < 100; i++ {
m[i] = fmt.Sprint(i)
}
got := map[string]bool{}
hb := &hashBuffer{Hash: sha256.New()}
hash := lookupTypeHasher(reflect.TypeOf(m))
for i := 0; i < 20; i++ {
va := reflect.ValueOf(&m).Elem()
hb.Reset()
h := new(hasher)
h.Block512.Hash = hb
hash(h, pointerOf(va.Addr()))
h.sum()
if got[string(hb.B)] {
continue
}
got[string(hb.B)] = 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
}
util/deephash: improve cycle detection (#2470) The previous algorithm used a map of all visited pointers. The strength of this approach is that it quickly prunes any nodes that we have ever visited before. The detriment of the approach is that pruning is heavily dependent on the order that pointers were visited. This is especially relevant for hashing a map where map entries are visited in a non-deterministic manner, which would cause the map hash to be non-deterministic (which defeats the point of a hash). This new algorithm uses a stack of all visited pointers, similar to how github.com/google/go-cmp performs cycle detection. When we visit a pointer, we push it onto the stack, and when we leave a pointer, we pop it from the stack. Before visiting a pointer, we first check whether the pointer exists anywhere in the stack. If yes, then we prune the node. The detriment of this approach is that we may hash a node more often than before since we do not prune as aggressively. The set of visited pointers up until any node is only the path of nodes up to that node and not any other pointers that may have been visited elsewhere. This provides us deterministic hashing regardless of visit order. We can now delete hashMapFallback and associated complexity, which only exists because the previous approach was non-deterministic in the presence of cycles. This fixes a failure of the old algorithm where obviously different values are treated as equal because the pruning was too aggresive. See https://github.com/tailscale/tailscale/issues/2443#issuecomment-883653534 The new algorithm is slightly slower since it prunes less aggresively: name old time/op new time/op delta Hash-8 66.1µs ± 1% 68.8µs ± 1% +4.09% (p=0.000 n=19+19) HashMapAcyclic-8 63.0µs ± 1% 62.5µs ± 1% -0.76% (p=0.000 n=18+19) TailcfgNode-8 9.79µs ± 2% 9.88µs ± 1% +0.95% (p=0.000 n=19+17) HashArray-8 643ns ± 1% 653ns ± 1% +1.64% (p=0.000 n=19+19) However, a slower but more correct algorithm seems more favorable than a faster but incorrect algorithm. Signed-off-by: Joe Tsai <joetsai@digital-static.net>
3 years ago
x := T{X: [32]byte{1: 1, 31: 31}}
hb := &hashBuffer{Hash: sha256.New()}
h := new(hasher)
h.Block512.Hash = hb
va := reflect.ValueOf(&x).Elem()
hash := lookupTypeHasher(va.Type())
hash(h, pointerOf(va.Addr()))
h.sum()
util/deephash: remove unnecessary formatting for structs and slices (#2571) The index for every struct field or slice element and the number of fields for the struct is unncessary. The hashing of Go values is unambiguous because every type (except maps) encodes in a parsable manner. So long as we know the type information, we could theoretically decode every value (except for maps). At a high level: * numbers are encoded as fixed-width records according to precision. * strings (and AppendTo output) are encoded with a fixed-width length, followed by the contents of the buffer. * slices are prefixed by a fixed-width length, followed by the encoding of each value. So long as we know the type of each element, we could theoretically decode each element. * arrays are encoded just like slices, but elide the length since it is determined from the Go type. * maps are encoded first with a byte indicating whether it is a cycle. If a cycle, it is followed by a fixed-width index for the pointer, otherwise followed by the SHA-256 hash of its contents. The encoding of maps is not decodeable, but a SHA-256 hash is sufficient to avoid ambiguities. * interfaces are encoded first with a byte indicating whether it is nil. If not nil, it is followed by a fixed-width index for the type, and then the encoding for the underlying value. Having the type be encoded first ensures that the value could theoretically be decoded next. * pointers are encoded first with a byte indicating whether it is 1) nil, 2) a cycle, or 3) newly seen. If a cycle, it is followed by a fixed-width index for the pointer. If newly seen, it is followed by the encoding for the pointed-at value. Removing unnecessary details speeds up hashing: name old time/op new time/op delta Hash-8 76.0µs ± 1% 55.8µs ± 2% -26.62% (p=0.000 n=10+10) HashMapAcyclic-8 61.9µs ± 0% 62.0µs ± 0% ~ (p=0.666 n=9+9) TailcfgNode-8 10.2µs ± 1% 7.5µs ± 1% -26.90% (p=0.000 n=10+9) HashArray-8 1.07µs ± 1% 0.70µs ± 1% -34.67% (p=0.000 n=10+9) Signed-off-by: Joe Tsai <joetsai@digital-static.net>
3 years ago
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 := hb.B; 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)
}
hb := &hashBuffer{Hash: sha256.New()}
va := reflect.ValueOf(&m).Elem()
hash := lookupTypeHasher(va.Type())
h := new(hasher)
h.Block512.Hash = hb
for i := 0; i < b.N; i++ {
h.Reset()
hash(h, pointerOf(va.Addr()))
}
}
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]any
}
v := &T{
M: map[string]any{},
}
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)
}
}
// Test for http://go/corp/6311 issue.
func TestHashThroughView(t *testing.T) {
type sshPolicyOut struct {
Rules []tailcfg.SSHRuleView
}
type mapResponseOut struct {
SSHPolicy *sshPolicyOut
}
// Just test we don't panic:
_ = Hash(&mapResponseOut{
SSHPolicy: &sshPolicyOut{
Rules: []tailcfg.SSHRuleView{
(&tailcfg.SSHRule{
RuleExpires: ptrTo(time.Unix(123, 0)),
}).View(),
},
},
})
}
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)
}
}
// hashBuffer is a hash.Hash that buffers all written data.
type hashBuffer struct {
hash.Hash
B []byte
}
func (h *hashBuffer) Write(b []byte) (int, error) {
n, err := h.Hash.Write(b)
h.B = append(h.B, b[:n]...)
return n, err
}
func (h *hashBuffer) Reset() {
h.Hash.Reset()
h.B = h.B[:0]
}
func FuzzTime(f *testing.F) {
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(0), false, "", 0)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(0), true, "", 0)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(0), true, "hello", 0)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(0), true, "", 1234)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(0), true, "hello", 1234)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(1), false, "", 0)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(1), true, "", 0)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(1), true, "hello", 0)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(1), true, "", 1234)
f.Add(int64(0), int64(0), false, "", 0, int64(0), int64(1), true, "hello", 1234)
f.Add(int64(math.MaxInt64), int64(math.MaxInt64), false, "", 0, int64(math.MaxInt64), int64(math.MaxInt64), false, "", 0)
f.Add(int64(math.MaxInt64), int64(math.MaxInt64), false, "", 0, int64(math.MaxInt64), int64(math.MaxInt64), true, "", 0)
f.Add(int64(math.MaxInt64), int64(math.MaxInt64), false, "", 0, int64(math.MaxInt64), int64(math.MaxInt64), true, "hello", 0)
f.Add(int64(math.MaxInt64), int64(math.MaxInt64), false, "", 0, int64(math.MaxInt64), int64(math.MaxInt64), true, "", 1234)
f.Add(int64(math.MaxInt64), int64(math.MaxInt64), false, "", 0, int64(math.MaxInt64), int64(math.MaxInt64), true, "hello", 1234)
f.Add(int64(math.MinInt64), int64(math.MinInt64), false, "", 0, int64(math.MinInt64), int64(math.MinInt64), false, "", 0)
f.Add(int64(math.MinInt64), int64(math.MinInt64), false, "", 0, int64(math.MinInt64), int64(math.MinInt64), true, "", 0)
f.Add(int64(math.MinInt64), int64(math.MinInt64), false, "", 0, int64(math.MinInt64), int64(math.MinInt64), true, "hello", 0)
f.Add(int64(math.MinInt64), int64(math.MinInt64), false, "", 0, int64(math.MinInt64), int64(math.MinInt64), true, "", 1234)
f.Add(int64(math.MinInt64), int64(math.MinInt64), false, "", 0, int64(math.MinInt64), int64(math.MinInt64), true, "hello", 1234)
f.Fuzz(func(t *testing.T,
s1, ns1 int64, loc1 bool, name1 string, off1 int,
s2, ns2 int64, loc2 bool, name2 string, off2 int,
) {
t1 := time.Unix(s1, ns1)
if loc1 {
t1.In(time.FixedZone(name1, off1))
}
t2 := time.Unix(s2, ns2)
if loc2 {
t2.In(time.FixedZone(name2, off2))
}
got := Hash(&t1) == Hash(&t2)
want := t1.Format(time.RFC3339Nano) == t2.Format(time.RFC3339Nano)
if got != want {
t.Errorf("time.Time(%s) == time.Time(%s) mismatches hash equivalent", t1.Format(time.RFC3339Nano), t2.Format(time.RFC3339Nano))
}
})
}
func FuzzAddr(f *testing.F) {
f.Fuzz(func(t *testing.T,
u1a, u1b uint64, zone1 string,
u2a, u2b uint64, zone2 string,
) {
var b1, b2 [16]byte
binary.LittleEndian.PutUint64(b1[:8], u1a)
binary.LittleEndian.PutUint64(b1[8:], u1b)
binary.LittleEndian.PutUint64(b2[:8], u2a)
binary.LittleEndian.PutUint64(b2[8:], u2b)
var ips [4]netip.Addr
ips[0] = netip.AddrFrom4(*(*[4]byte)(b1[:]))
ips[1] = netip.AddrFrom4(*(*[4]byte)(b2[:]))
ips[2] = netip.AddrFrom16(b1)
if zone1 != "" {
ips[2] = ips[2].WithZone(zone1)
}
ips[3] = netip.AddrFrom16(b2)
if zone2 != "" {
ips[3] = ips[2].WithZone(zone2)
}
for _, ip1 := range ips[:] {
for _, ip2 := range ips[:] {
got := Hash(&ip1) == Hash(&ip2)
want := ip1 == ip2
if got != want {
t.Errorf("netip.Addr(%s) == netip.Addr(%s) mismatches hash equivalent", ip1.String(), ip2.String())
}
}
}
})
}