p2p/enr: initial implementation (#15585)

Initial implementation of ENR according to ethereum/EIPs#778
This commit is contained in:
Anton Evangelatov 2017-12-29 21:18:51 +01:00 committed by Felix Lange
parent f7ca03ae87
commit 36a10875c8
3 changed files with 768 additions and 0 deletions

290
p2p/enr/enr.go Normal file

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// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
// Package enr implements Ethereum Node Records as defined in EIP-778. A node record holds
// arbitrary information about a node on the peer-to-peer network.
//
// Records contain named keys. To store and retrieve key/values in a record, use the Entry
// interface.
//
// Records must be signed before transmitting them to another node. Decoding a record verifies
// its signature. When creating a record, set the entries you want, then call Sign to add the
// signature. Modifying a record invalidates the signature.
//
// Package enr supports the "secp256k1-keccak" identity scheme.
package enr
import (
"bytes"
"crypto/ecdsa"
"errors"
"fmt"
"io"
"sort"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/crypto/sha3"
"github.com/ethereum/go-ethereum/rlp"
)
const SizeLimit = 300 // maximum encoded size of a node record in bytes
const ID_SECP256k1_KECCAK = ID("secp256k1-keccak") // the default identity scheme
var (
errNoID = errors.New("unknown or unspecified identity scheme")
errInvalidSigsize = errors.New("invalid signature size")
errInvalidSig = errors.New("invalid signature")
errNotSorted = errors.New("record key/value pairs are not sorted by key")
errDuplicateKey = errors.New("record contains duplicate key")
errIncompletePair = errors.New("record contains incomplete k/v pair")
errTooBig = fmt.Errorf("record bigger than %d bytes", SizeLimit)
errEncodeUnsigned = errors.New("can't encode unsigned record")
errNotFound = errors.New("no such key in record")
)
// Record represents a node record. The zero value is an empty record.
type Record struct {
seq uint64 // sequence number
signature []byte // the signature
raw []byte // RLP encoded record
pairs []pair // sorted list of all key/value pairs
}
// pair is a key/value pair in a record.
type pair struct {
k string
v rlp.RawValue
}
// Signed reports whether the record has a valid signature.
func (r *Record) Signed() bool {
return r.signature != nil
}
// Seq returns the sequence number.
func (r *Record) Seq() uint64 {
return r.seq
}
// SetSeq updates the record sequence number. This invalidates any signature on the record.
// Calling SetSeq is usually not required because signing the redord increments the
// sequence number.
func (r *Record) SetSeq(s uint64) {
r.signature = nil
r.raw = nil
r.seq = s
}
// Load retrieves the value of a key/value pair. The given Entry must be a pointer and will
// be set to the value of the entry in the record.
//
// Errors returned by Load are wrapped in KeyError. You can distinguish decoding errors
// from missing keys using the IsNotFound function.
func (r *Record) Load(e Entry) error {
i := sort.Search(len(r.pairs), func(i int) bool { return r.pairs[i].k >= e.ENRKey() })
if i < len(r.pairs) && r.pairs[i].k == e.ENRKey() {
if err := rlp.DecodeBytes(r.pairs[i].v, e); err != nil {
return &KeyError{Key: e.ENRKey(), Err: err}
}
return nil
}
return &KeyError{Key: e.ENRKey(), Err: errNotFound}
}
// Set adds or updates the given entry in the record.
// It panics if the value can't be encoded.
func (r *Record) Set(e Entry) {
r.signature = nil
r.raw = nil
blob, err := rlp.EncodeToBytes(e)
if err != nil {
panic(fmt.Errorf("enr: can't encode %s: %v", e.ENRKey(), err))
}
i := sort.Search(len(r.pairs), func(i int) bool { return r.pairs[i].k >= e.ENRKey() })
if i < len(r.pairs) && r.pairs[i].k == e.ENRKey() {
// element is present at r.pairs[i]
r.pairs[i].v = blob
return
} else if i < len(r.pairs) {
// insert pair before i-th elem
el := pair{e.ENRKey(), blob}
r.pairs = append(r.pairs, pair{})
copy(r.pairs[i+1:], r.pairs[i:])
r.pairs[i] = el
return
}
// element should be placed at the end of r.pairs
r.pairs = append(r.pairs, pair{e.ENRKey(), blob})
}
// EncodeRLP implements rlp.Encoder. Encoding fails if
// the record is unsigned.
func (r Record) EncodeRLP(w io.Writer) error {
if !r.Signed() {
return errEncodeUnsigned
}
_, err := w.Write(r.raw)
return err
}
// DecodeRLP implements rlp.Decoder. Decoding verifies the signature.
func (r *Record) DecodeRLP(s *rlp.Stream) error {
raw, err := s.Raw()
if err != nil {
return err
}
if len(raw) > SizeLimit {
return errTooBig
}
// Decode the RLP container.
dec := Record{raw: raw}
s = rlp.NewStream(bytes.NewReader(raw), 0)
if _, err := s.List(); err != nil {
return err
}
if err = s.Decode(&dec.signature); err != nil {
return err
}
if err = s.Decode(&dec.seq); err != nil {
return err
}
// The rest of the record contains sorted k/v pairs.
var prevkey string
for i := 0; ; i++ {
var kv pair
if err := s.Decode(&kv.k); err != nil {
if err == rlp.EOL {
break
}
return err
}
if err := s.Decode(&kv.v); err != nil {
if err == rlp.EOL {
return errIncompletePair
}
return err
}
if i > 0 {
if kv.k == prevkey {
return errDuplicateKey
}
if kv.k < prevkey {
return errNotSorted
}
}
dec.pairs = append(dec.pairs, kv)
prevkey = kv.k
}
if err := s.ListEnd(); err != nil {
return err
}
// Verify signature.
if err = dec.verifySignature(); err != nil {
return err
}
*r = dec
return nil
}
type s256raw []byte
func (s256raw) ENRKey() string { return "secp256k1" }
// NodeAddr returns the node address. The return value will be nil if the record is
// unsigned.
func (r *Record) NodeAddr() []byte {
var entry s256raw
if r.Load(&entry) != nil {
return nil
}
return crypto.Keccak256(entry)
}
// Sign signs the record with the given private key. It updates the record's identity
// scheme, public key and increments the sequence number. Sign returns an error if the
// encoded record is larger than the size limit.
func (r *Record) Sign(privkey *ecdsa.PrivateKey) error {
r.seq = r.seq + 1
r.Set(ID_SECP256k1_KECCAK)
r.Set(Secp256k1(privkey.PublicKey))
return r.signAndEncode(privkey)
}
func (r *Record) appendPairs(list []interface{}) []interface{} {
list = append(list, r.seq)
for _, p := range r.pairs {
list = append(list, p.k, p.v)
}
return list
}
func (r *Record) signAndEncode(privkey *ecdsa.PrivateKey) error {
// Put record elements into a flat list. Leave room for the signature.
list := make([]interface{}, 1, len(r.pairs)*2+2)
list = r.appendPairs(list)
// Sign the tail of the list.
h := sha3.NewKeccak256()
rlp.Encode(h, list[1:])
sig, err := crypto.Sign(h.Sum(nil), privkey)
if err != nil {
return err
}
sig = sig[:len(sig)-1] // remove v
// Put signature in front.
r.signature, list[0] = sig, sig
r.raw, err = rlp.EncodeToBytes(list)
if err != nil {
return err
}
if len(r.raw) > SizeLimit {
return errTooBig
}
return nil
}
func (r *Record) verifySignature() error {
// Get identity scheme, public key, signature.
var id ID
var entry s256raw
if err := r.Load(&id); err != nil {
return err
} else if id != ID_SECP256k1_KECCAK {
return errNoID
}
if err := r.Load(&entry); err != nil {
return err
} else if len(entry) != 33 {
return fmt.Errorf("invalid public key")
}
// Verify the signature.
list := make([]interface{}, 0, len(r.pairs)*2+1)
list = r.appendPairs(list)
h := sha3.NewKeccak256()
rlp.Encode(h, list)
if !crypto.VerifySignature(entry, h.Sum(nil), r.signature) {
return errInvalidSig
}
return nil
}

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p2p/enr/enr_test.go Normal file

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// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package enr
import (
"bytes"
"encoding/hex"
"fmt"
"math/rand"
"testing"
"time"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/rlp"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
var (
privkey, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
pubkey = &privkey.PublicKey
)
var rnd = rand.New(rand.NewSource(time.Now().UnixNano()))
func randomString(strlen int) string {
b := make([]byte, strlen)
rnd.Read(b)
return string(b)
}
// TestGetSetID tests encoding/decoding and setting/getting of the ID key.
func TestGetSetID(t *testing.T) {
id := ID("someid")
var r Record
r.Set(id)
var id2 ID
require.NoError(t, r.Load(&id2))
assert.Equal(t, id, id2)
}
// TestGetSetIP4 tests encoding/decoding and setting/getting of the IP4 key.
func TestGetSetIP4(t *testing.T) {
ip := IP4{192, 168, 0, 3}
var r Record
r.Set(ip)
var ip2 IP4
require.NoError(t, r.Load(&ip2))
assert.Equal(t, ip, ip2)
}
// TestGetSetIP6 tests encoding/decoding and setting/getting of the IP6 key.
func TestGetSetIP6(t *testing.T) {
ip := IP6{0x20, 0x01, 0x48, 0x60, 0, 0, 0x20, 0x01, 0, 0, 0, 0, 0, 0, 0x00, 0x68}
var r Record
r.Set(ip)
var ip2 IP6
require.NoError(t, r.Load(&ip2))
assert.Equal(t, ip, ip2)
}
// TestGetSetDiscPort tests encoding/decoding and setting/getting of the DiscPort key.
func TestGetSetDiscPort(t *testing.T) {
port := DiscPort(30309)
var r Record
r.Set(port)
var port2 DiscPort
require.NoError(t, r.Load(&port2))
assert.Equal(t, port, port2)
}
// TestGetSetSecp256k1 tests encoding/decoding and setting/getting of the Secp256k1 key.
func TestGetSetSecp256k1(t *testing.T) {
var r Record
if err := r.Sign(privkey); err != nil {
t.Fatal(err)
}
var pk Secp256k1
require.NoError(t, r.Load(&pk))
assert.EqualValues(t, pubkey, &pk)
}
func TestLoadErrors(t *testing.T) {
var r Record
ip4 := IP4{127, 0, 0, 1}
r.Set(ip4)
// Check error for missing keys.
var ip6 IP6
err := r.Load(&ip6)
if !IsNotFound(err) {
t.Error("IsNotFound should return true for missing key")
}
assert.Equal(t, &KeyError{Key: ip6.ENRKey(), Err: errNotFound}, err)
// Check error for invalid keys.
var list []uint
err = r.Load(WithEntry(ip4.ENRKey(), &list))
kerr, ok := err.(*KeyError)
if !ok {
t.Fatalf("expected KeyError, got %T", err)
}
assert.Equal(t, kerr.Key, ip4.ENRKey())
assert.Error(t, kerr.Err)
if IsNotFound(err) {
t.Error("IsNotFound should return false for decoding errors")
}
}
// TestSortedGetAndSet tests that Set produced a sorted pairs slice.
func TestSortedGetAndSet(t *testing.T) {
type pair struct {
k string
v uint32
}
for _, tt := range []struct {
input []pair
want []pair
}{
{
input: []pair{{"a", 1}, {"c", 2}, {"b", 3}},
want: []pair{{"a", 1}, {"b", 3}, {"c", 2}},
},
{
input: []pair{{"a", 1}, {"c", 2}, {"b", 3}, {"d", 4}, {"a", 5}, {"bb", 6}},
want: []pair{{"a", 5}, {"b", 3}, {"bb", 6}, {"c", 2}, {"d", 4}},
},
{
input: []pair{{"c", 2}, {"b", 3}, {"d", 4}, {"a", 5}, {"bb", 6}},
want: []pair{{"a", 5}, {"b", 3}, {"bb", 6}, {"c", 2}, {"d", 4}},
},
} {
var r Record
for _, i := range tt.input {
r.Set(WithEntry(i.k, &i.v))
}
for i, w := range tt.want {
// set got's key from r.pair[i], so that we preserve order of pairs
got := pair{k: r.pairs[i].k}
assert.NoError(t, r.Load(WithEntry(w.k, &got.v)))
assert.Equal(t, w, got)
}
}
}
// TestDirty tests record signature removal on setting of new key/value pair in record.
func TestDirty(t *testing.T) {
var r Record
if r.Signed() {
t.Error("Signed returned true for zero record")
}
if _, err := rlp.EncodeToBytes(r); err != errEncodeUnsigned {
t.Errorf("expected errEncodeUnsigned, got %#v", err)
}
require.NoError(t, r.Sign(privkey))
if !r.Signed() {
t.Error("Signed return false for signed record")
}
_, err := rlp.EncodeToBytes(r)
assert.NoError(t, err)
r.SetSeq(3)
if r.Signed() {
t.Error("Signed returned true for modified record")
}
if _, err := rlp.EncodeToBytes(r); err != errEncodeUnsigned {
t.Errorf("expected errEncodeUnsigned, got %#v", err)
}
}
// TestGetSetOverwrite tests value overwrite when setting a new value with an existing key in record.
func TestGetSetOverwrite(t *testing.T) {
var r Record
ip := IP4{192, 168, 0, 3}
r.Set(ip)
ip2 := IP4{192, 168, 0, 4}
r.Set(ip2)
var ip3 IP4
require.NoError(t, r.Load(&ip3))
assert.Equal(t, ip2, ip3)
}
// TestSignEncodeAndDecode tests signing, RLP encoding and RLP decoding of a record.
func TestSignEncodeAndDecode(t *testing.T) {
var r Record
r.Set(DiscPort(30303))
r.Set(IP4{127, 0, 0, 1})
require.NoError(t, r.Sign(privkey))
blob, err := rlp.EncodeToBytes(r)
require.NoError(t, err)
var r2 Record
require.NoError(t, rlp.DecodeBytes(blob, &r2))
assert.Equal(t, r, r2)
blob2, err := rlp.EncodeToBytes(r2)
require.NoError(t, err)
assert.Equal(t, blob, blob2)
}
func TestNodeAddr(t *testing.T) {
var r Record
if addr := r.NodeAddr(); addr != nil {
t.Errorf("wrong address on empty record: got %v, want %v", addr, nil)
}
require.NoError(t, r.Sign(privkey))
expected := "caaa1485d83b18b32ed9ad666026151bf0cae8a0a88c857ae2d4c5be2daa6726"
assert.Equal(t, expected, hex.EncodeToString(r.NodeAddr()))
}
var pyRecord, _ = hex.DecodeString("f896b840954dc36583c1f4b69ab59b1375f362f06ee99f3723cd77e64b6de6d211c27d7870642a79d4516997f94091325d2a7ca6215376971455fb221d34f35b277149a1018664697363763582765f82696490736563703235366b312d6b656363616b83697034847f00000189736563703235366b31a103ca634cae0d49acb401d8a4c6b6fe8c55b70d115bf400769cc1400f3258cd3138")
// TestPythonInterop checks that we can decode and verify a record produced by the Python
// implementation.
func TestPythonInterop(t *testing.T) {
var r Record
if err := rlp.DecodeBytes(pyRecord, &r); err != nil {
t.Fatalf("can't decode: %v", err)
}
var (
wantAddr, _ = hex.DecodeString("caaa1485d83b18b32ed9ad666026151bf0cae8a0a88c857ae2d4c5be2daa6726")
wantSeq = uint64(1)
wantIP = IP4{127, 0, 0, 1}
wantDiscport = DiscPort(30303)
)
if r.Seq() != wantSeq {
t.Errorf("wrong seq: got %d, want %d", r.Seq(), wantSeq)
}
if addr := r.NodeAddr(); !bytes.Equal(addr, wantAddr) {
t.Errorf("wrong addr: got %x, want %x", addr, wantAddr)
}
want := map[Entry]interface{}{new(IP4): &wantIP, new(DiscPort): &wantDiscport}
for k, v := range want {
desc := fmt.Sprintf("loading key %q", k.ENRKey())
if assert.NoError(t, r.Load(k), desc) {
assert.Equal(t, k, v, desc)
}
}
}
// TestRecordTooBig tests that records bigger than SizeLimit bytes cannot be signed.
func TestRecordTooBig(t *testing.T) {
var r Record
key := randomString(10)
// set a big value for random key, expect error
r.Set(WithEntry(key, randomString(300)))
if err := r.Sign(privkey); err != errTooBig {
t.Fatalf("expected to get errTooBig, got %#v", err)
}
// set an acceptable value for random key, expect no error
r.Set(WithEntry(key, randomString(100)))
require.NoError(t, r.Sign(privkey))
}
// TestSignEncodeAndDecodeRandom tests encoding/decoding of records containing random key/value pairs.
func TestSignEncodeAndDecodeRandom(t *testing.T) {
var r Record
// random key/value pairs for testing
pairs := map[string]uint32{}
for i := 0; i < 10; i++ {
key := randomString(7)
value := rnd.Uint32()
pairs[key] = value
r.Set(WithEntry(key, &value))
}
require.NoError(t, r.Sign(privkey))
_, err := rlp.EncodeToBytes(r)
require.NoError(t, err)
for k, v := range pairs {
desc := fmt.Sprintf("key %q", k)
var got uint32
buf := WithEntry(k, &got)
require.NoError(t, r.Load(buf), desc)
require.Equal(t, v, got, desc)
}
}
func BenchmarkDecode(b *testing.B) {
var r Record
for i := 0; i < b.N; i++ {
rlp.DecodeBytes(pyRecord, &r)
}
b.StopTimer()
r.NodeAddr()
}

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p2p/enr/entries.go Normal file

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// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package enr
import (
"crypto/ecdsa"
"fmt"
"io"
"net"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/rlp"
)
// Entry is implemented by known node record entry types.
//
// To define a new entry that is to be included in a node record,
// create a Go type that satisfies this interface. The type should
// also implement rlp.Decoder if additional checks are needed on the value.
type Entry interface {
ENRKey() string
}
type generic struct {
key string
value interface{}
}
func (g generic) ENRKey() string { return g.key }
func (g generic) EncodeRLP(w io.Writer) error {
return rlp.Encode(w, g.value)
}
func (g *generic) DecodeRLP(s *rlp.Stream) error {
return s.Decode(g.value)
}
// WithEntry wraps any value with a key name. It can be used to set and load arbitrary values
// in a record. The value v must be supported by rlp. To use WithEntry with Load, the value
// must be a pointer.
func WithEntry(k string, v interface{}) Entry {
return &generic{key: k, value: v}
}
// DiscPort is the "discv5" key, which holds the UDP port for discovery v5.
type DiscPort uint16
func (v DiscPort) ENRKey() string { return "discv5" }
// ID is the "id" key, which holds the name of the identity scheme.
type ID string
func (v ID) ENRKey() string { return "id" }
// IP4 is the "ip4" key, which holds a 4-byte IPv4 address.
type IP4 net.IP
func (v IP4) ENRKey() string { return "ip4" }
// EncodeRLP implements rlp.Encoder.
func (v IP4) EncodeRLP(w io.Writer) error {
ip4 := net.IP(v).To4()
if ip4 == nil {
return fmt.Errorf("invalid IPv4 address: %v", v)
}
return rlp.Encode(w, ip4)
}
// DecodeRLP implements rlp.Decoder.
func (v *IP4) DecodeRLP(s *rlp.Stream) error {
if err := s.Decode((*net.IP)(v)); err != nil {
return err
}
if len(*v) != 4 {
return fmt.Errorf("invalid IPv4 address, want 4 bytes: %v", *v)
}
return nil
}
// IP6 is the "ip6" key, which holds a 16-byte IPv6 address.
type IP6 net.IP
func (v IP6) ENRKey() string { return "ip6" }
// EncodeRLP implements rlp.Encoder.
func (v IP6) EncodeRLP(w io.Writer) error {
ip6 := net.IP(v)
return rlp.Encode(w, ip6)
}
// DecodeRLP implements rlp.Decoder.
func (v *IP6) DecodeRLP(s *rlp.Stream) error {
if err := s.Decode((*net.IP)(v)); err != nil {
return err
}
if len(*v) != 16 {
return fmt.Errorf("invalid IPv6 address, want 16 bytes: %v", *v)
}
return nil
}
// Secp256k1 is the "secp256k1" key, which holds a public key.
type Secp256k1 ecdsa.PublicKey
func (v Secp256k1) ENRKey() string { return "secp256k1" }
// EncodeRLP implements rlp.Encoder.
func (v Secp256k1) EncodeRLP(w io.Writer) error {
return rlp.Encode(w, crypto.CompressPubkey((*ecdsa.PublicKey)(&v)))
}
// DecodeRLP implements rlp.Decoder.
func (v *Secp256k1) DecodeRLP(s *rlp.Stream) error {
buf, err := s.Bytes()
if err != nil {
return err
}
pk, err := crypto.DecompressPubkey(buf)
if err != nil {
return err
}
*v = (Secp256k1)(*pk)
return nil
}
// KeyError is an error related to a key.
type KeyError struct {
Key string
Err error
}
// Error implements error.
func (err *KeyError) Error() string {
if err.Err == errNotFound {
return fmt.Sprintf("missing ENR key %q", err.Key)
}
return fmt.Sprintf("ENR key %q: %v", err.Key, err.Err)
}
// IsNotFound reports whether the given error means that a key/value pair is
// missing from a record.
func IsNotFound(err error) bool {
kerr, ok := err.(*KeyError)
return ok && kerr.Err == errNotFound
}