erigon-pulse/p2p/enr/enr.go
Felix Lange 30cd5c1854
all: new p2p node representation (#17643)
Package p2p/enode provides a generalized representation of p2p nodes
which can contain arbitrary information in key/value pairs. It is also
the new home for the node database. The "v4" identity scheme is also
moved here from p2p/enr to remove the dependency on Ethereum crypto from
that package.

Record signature handling is changed significantly. The identity scheme
registry is removed and acceptable schemes must be passed to any method
that needs identity. This means records must now be validated explicitly
after decoding.

The enode API is designed to make signature handling easy and safe: most
APIs around the codebase work with enode.Node, which is a wrapper around
a valid record. Going from enr.Record to enode.Node requires a valid
signature.

* p2p/discover: port to p2p/enode

This ports the discovery code to the new node representation in
p2p/enode. The wire protocol is unchanged, this can be considered a
refactoring change. The Kademlia table can now deal with nodes using an
arbitrary identity scheme. This requires a few incompatible API changes:

  - Table.Lookup is not available anymore. It used to take a public key
    as argument because v4 protocol requires one. Its replacement is
    LookupRandom.
  - Table.Resolve takes *enode.Node instead of NodeID. This is also for
    v4 protocol compatibility because nodes cannot be looked up by ID
    alone.
  - Types Node and NodeID are gone. Further commits in the series will be
    fixes all over the the codebase to deal with those removals.

* p2p: port to p2p/enode and discovery changes

This adapts package p2p to the changes in p2p/discover. All uses of
discover.Node and discover.NodeID are replaced by their equivalents from
p2p/enode.

New API is added to retrieve the enode.Node instance of a peer. The
behavior of Server.Self with discovery disabled is improved. It now
tries much harder to report a working IP address, falling back to
127.0.0.1 if no suitable address can be determined through other means.
These changes were needed for tests of other packages later in the
series.

* p2p/simulations, p2p/testing: port to p2p/enode

No surprises here, mostly replacements of discover.Node, discover.NodeID
with their new equivalents. The 'interesting' API changes are:

 - testing.ProtocolSession tracks complete nodes, not just their IDs.
 - adapters.NodeConfig has a new method to create a complete node.

These changes were needed to make swarm tests work.

Note that the NodeID change makes the code incompatible with old
simulation snapshots.

* whisper/whisperv5, whisper/whisperv6: port to p2p/enode

This port was easy because whisper uses []byte for node IDs and
URL strings in the API.

* eth: port to p2p/enode

Again, easy to port because eth uses strings for node IDs and doesn't
care about node information in any way.

* les: port to p2p/enode

Apart from replacing discover.NodeID with enode.ID, most changes are in
the server pool code. It now deals with complete nodes instead
of (Pubkey, IP, Port) triples. The database format is unchanged for now,
but we should probably change it to use the node database later.

* node: port to p2p/enode

This change simply replaces discover.Node and discover.NodeID with their
new equivalents.

* swarm/network: port to p2p/enode

Swarm has its own node address representation, BzzAddr, containing both
an overlay address (the hash of a secp256k1 public key) and an underlay
address (enode:// URL).

There are no changes to the BzzAddr format in this commit, but certain
operations such as creating a BzzAddr from a node ID are now impossible
because node IDs aren't public keys anymore.

Most swarm-related changes in the series remove uses of
NewAddrFromNodeID, replacing it with NewAddr which takes a complete node
as argument. ToOverlayAddr is removed because we can just use the node
ID directly.
2018-09-25 00:59:00 +02:00

301 lines
8.5 KiB
Go

// 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. Node information is
// stored in key/value pairs. To store and retrieve key/values in a record, use the Entry
// interface.
//
// Signature Handling
//
// Records must be signed before transmitting them to another node.
//
// Decoding a record doesn't check its signature. Code working with records from an
// untrusted source must always verify two things: that the record uses an identity scheme
// deemed secure, and that the signature is valid according to the declared scheme.
//
// When creating a record, set the entries you want and use a signing function provided by
// the identity scheme to add the signature. Modifying a record invalidates the signature.
//
// Package enr supports the "secp256k1-keccak" identity scheme.
package enr
import (
"bytes"
"errors"
"fmt"
"io"
"sort"
"github.com/ethereum/go-ethereum/rlp"
)
const SizeLimit = 300 // maximum encoded size of a node record in bytes
var (
ErrInvalidSig = errors.New("invalid signature on node record")
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")
)
// An IdentityScheme is capable of verifying record signatures and
// deriving node addresses.
type IdentityScheme interface {
Verify(r *Record, sig []byte) error
NodeAddr(r *Record) []byte
}
// SchemeMap is a registry of named identity schemes.
type SchemeMap map[string]IdentityScheme
func (m SchemeMap) Verify(r *Record, sig []byte) error {
s := m[r.IdentityScheme()]
if s == nil {
return ErrInvalidSig
}
return s.Verify(r, sig)
}
func (m SchemeMap) NodeAddr(r *Record) []byte {
s := m[r.IdentityScheme()]
if s == nil {
return nil
}
return s.NodeAddr(r)
}
// 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
}
// 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 setting any key in a signed record
// 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. If the record is signed, Set increments the sequence number and invalidates
// the sequence number.
func (r *Record) Set(e Entry) {
blob, err := rlp.EncodeToBytes(e)
if err != nil {
panic(fmt.Errorf("enr: can't encode %s: %v", e.ENRKey(), err))
}
r.invalidate()
pairs := make([]pair, len(r.pairs))
copy(pairs, r.pairs)
i := sort.Search(len(pairs), func(i int) bool { return pairs[i].k >= e.ENRKey() })
switch {
case i < len(pairs) && pairs[i].k == e.ENRKey():
// element is present at r.pairs[i]
pairs[i].v = blob
case i < len(r.pairs):
// insert pair before i-th elem
el := pair{e.ENRKey(), blob}
pairs = append(pairs, pair{})
copy(pairs[i+1:], pairs[i:])
pairs[i] = el
default:
// element should be placed at the end of r.pairs
pairs = append(pairs, pair{e.ENRKey(), blob})
}
r.pairs = pairs
}
func (r *Record) invalidate() {
if r.signature == nil {
r.seq++
}
r.signature = nil
r.raw = nil
}
// EncodeRLP implements rlp.Encoder. Encoding fails if
// the record is unsigned.
func (r Record) EncodeRLP(w io.Writer) error {
if r.signature == nil {
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 {
dec, raw, err := decodeRecord(s)
if err != nil {
return err
}
*r = dec
r.raw = raw
return nil
}
func decodeRecord(s *rlp.Stream) (dec Record, raw []byte, err error) {
raw, err = s.Raw()
if err != nil {
return dec, raw, err
}
if len(raw) > SizeLimit {
return dec, raw, errTooBig
}
// Decode the RLP container.
s = rlp.NewStream(bytes.NewReader(raw), 0)
if _, err := s.List(); err != nil {
return dec, raw, err
}
if err = s.Decode(&dec.signature); err != nil {
return dec, raw, err
}
if err = s.Decode(&dec.seq); err != nil {
return dec, raw, 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 dec, raw, err
}
if err := s.Decode(&kv.v); err != nil {
if err == rlp.EOL {
return dec, raw, errIncompletePair
}
return dec, raw, err
}
if i > 0 {
if kv.k == prevkey {
return dec, raw, errDuplicateKey
}
if kv.k < prevkey {
return dec, raw, errNotSorted
}
}
dec.pairs = append(dec.pairs, kv)
prevkey = kv.k
}
return dec, raw, s.ListEnd()
}
// IdentityScheme returns the name of the identity scheme in the record.
func (r *Record) IdentityScheme() string {
var id ID
r.Load(&id)
return string(id)
}
// VerifySignature checks whether the record is signed using the given identity scheme.
func (r *Record) VerifySignature(s IdentityScheme) error {
return s.Verify(r, r.signature)
}
// SetSig sets the record signature. It returns an error if the encoded record is larger
// than the size limit or if the signature is invalid according to the passed scheme.
//
// You can also use SetSig to remove the signature explicitly by passing a nil scheme
// and signature.
//
// SetSig panics when either the scheme or the signature (but not both) are nil.
func (r *Record) SetSig(s IdentityScheme, sig []byte) error {
switch {
// Prevent storing invalid data.
case s == nil && sig != nil:
panic("enr: invalid call to SetSig with non-nil signature but nil scheme")
case s != nil && sig == nil:
panic("enr: invalid call to SetSig with nil signature but non-nil scheme")
// Verify if we have a scheme.
case s != nil:
if err := s.Verify(r, sig); err != nil {
return err
}
raw, err := r.encode(sig)
if err != nil {
return err
}
r.signature, r.raw = sig, raw
// Reset otherwise.
default:
r.signature, r.raw = nil, nil
}
return nil
}
// AppendElements appends the sequence number and entries to the given slice.
func (r *Record) AppendElements(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) encode(sig []byte) (raw []byte, err error) {
list := make([]interface{}, 1, 2*len(r.pairs)+1)
list[0] = sig
list = r.AppendElements(list)
if raw, err = rlp.EncodeToBytes(list); err != nil {
return nil, err
}
if len(raw) > SizeLimit {
return nil, errTooBig
}
return raw, nil
}