plugeth/p2p/rlpx/rlpx.go
rene 129cf075e9
p2p: move rlpx into separate package (#21464)
This change moves the RLPx protocol implementation into a separate package,
p2p/rlpx. The new package can be used to establish RLPx connections for
protocol testing purposes.

Co-authored-by: Felix Lange <fjl@twurst.com>
2020-09-22 10:17:39 +02:00

670 lines
19 KiB
Go

// Copyright 2015 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 rlpx implements the RLPx transport protocol.
package rlpx
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/hmac"
"crypto/rand"
"encoding/binary"
"errors"
"fmt"
"hash"
"io"
mrand "math/rand"
"net"
"time"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/crypto/ecies"
"github.com/ethereum/go-ethereum/rlp"
"github.com/golang/snappy"
"golang.org/x/crypto/sha3"
)
// Conn is an RLPx network connection. It wraps a low-level network connection. The
// underlying connection should not be used for other activity when it is wrapped by Conn.
//
// Before sending messages, a handshake must be performed by calling the Handshake method.
// This type is not generally safe for concurrent use, but reading and writing of messages
// may happen concurrently after the handshake.
type Conn struct {
dialDest *ecdsa.PublicKey
conn net.Conn
handshake *handshakeState
snappy bool
}
type handshakeState struct {
enc cipher.Stream
dec cipher.Stream
macCipher cipher.Block
egressMAC hash.Hash
ingressMAC hash.Hash
}
// NewConn wraps the given network connection. If dialDest is non-nil, the connection
// behaves as the initiator during the handshake.
func NewConn(conn net.Conn, dialDest *ecdsa.PublicKey) *Conn {
return &Conn{
dialDest: dialDest,
conn: conn,
}
}
// SetSnappy enables or disables snappy compression of messages. This is usually called
// after the devp2p Hello message exchange when the negotiated version indicates that
// compression is available on both ends of the connection.
func (c *Conn) SetSnappy(snappy bool) {
c.snappy = snappy
}
// SetReadDeadline sets the deadline for all future read operations.
func (c *Conn) SetReadDeadline(time time.Time) error {
return c.conn.SetReadDeadline(time)
}
// SetWriteDeadline sets the deadline for all future write operations.
func (c *Conn) SetWriteDeadline(time time.Time) error {
return c.conn.SetWriteDeadline(time)
}
// SetDeadline sets the deadline for all future read and write operations.
func (c *Conn) SetDeadline(time time.Time) error {
return c.conn.SetDeadline(time)
}
// Read reads a message from the connection.
func (c *Conn) Read() (code uint64, data []byte, wireSize int, err error) {
if c.handshake == nil {
panic("can't ReadMsg before handshake")
}
frame, err := c.handshake.readFrame(c.conn)
if err != nil {
return 0, nil, 0, err
}
code, data, err = rlp.SplitUint64(frame)
if err != nil {
return 0, nil, 0, fmt.Errorf("invalid message code: %v", err)
}
wireSize = len(data)
// If snappy is enabled, verify and decompress message.
if c.snappy {
var actualSize int
actualSize, err = snappy.DecodedLen(data)
if err != nil {
return code, nil, 0, err
}
if actualSize > maxUint24 {
return code, nil, 0, errPlainMessageTooLarge
}
data, err = snappy.Decode(nil, data)
}
return code, data, wireSize, err
}
func (h *handshakeState) readFrame(conn io.Reader) ([]byte, error) {
// read the header
headbuf := make([]byte, 32)
if _, err := io.ReadFull(conn, headbuf); err != nil {
return nil, err
}
// verify header mac
shouldMAC := updateMAC(h.ingressMAC, h.macCipher, headbuf[:16])
if !hmac.Equal(shouldMAC, headbuf[16:]) {
return nil, errors.New("bad header MAC")
}
h.dec.XORKeyStream(headbuf[:16], headbuf[:16]) // first half is now decrypted
fsize := readInt24(headbuf)
// ignore protocol type for now
// read the frame content
var rsize = fsize // frame size rounded up to 16 byte boundary
if padding := fsize % 16; padding > 0 {
rsize += 16 - padding
}
framebuf := make([]byte, rsize)
if _, err := io.ReadFull(conn, framebuf); err != nil {
return nil, err
}
// read and validate frame MAC. we can re-use headbuf for that.
h.ingressMAC.Write(framebuf)
fmacseed := h.ingressMAC.Sum(nil)
if _, err := io.ReadFull(conn, headbuf[:16]); err != nil {
return nil, err
}
shouldMAC = updateMAC(h.ingressMAC, h.macCipher, fmacseed)
if !hmac.Equal(shouldMAC, headbuf[:16]) {
return nil, errors.New("bad frame MAC")
}
// decrypt frame content
h.dec.XORKeyStream(framebuf, framebuf)
return framebuf[:fsize], nil
}
// Write writes a message to the connection.
//
// Write returns the written size of the message data. This may be less than or equal to
// len(data) depending on whether snappy compression is enabled.
func (c *Conn) Write(code uint64, data []byte) (uint32, error) {
if c.handshake == nil {
panic("can't WriteMsg before handshake")
}
if len(data) > maxUint24 {
return 0, errPlainMessageTooLarge
}
if c.snappy {
data = snappy.Encode(nil, data)
}
wireSize := uint32(len(data))
err := c.handshake.writeFrame(c.conn, code, data)
return wireSize, err
}
func (h *handshakeState) writeFrame(conn io.Writer, code uint64, data []byte) error {
ptype, _ := rlp.EncodeToBytes(code)
// write header
headbuf := make([]byte, 32)
fsize := len(ptype) + len(data)
if fsize > maxUint24 {
return errPlainMessageTooLarge
}
putInt24(uint32(fsize), headbuf)
copy(headbuf[3:], zeroHeader)
h.enc.XORKeyStream(headbuf[:16], headbuf[:16]) // first half is now encrypted
// write header MAC
copy(headbuf[16:], updateMAC(h.egressMAC, h.macCipher, headbuf[:16]))
if _, err := conn.Write(headbuf); err != nil {
return err
}
// write encrypted frame, updating the egress MAC hash with
// the data written to conn.
tee := cipher.StreamWriter{S: h.enc, W: io.MultiWriter(conn, h.egressMAC)}
if _, err := tee.Write(ptype); err != nil {
return err
}
if _, err := tee.Write(data); err != nil {
return err
}
if padding := fsize % 16; padding > 0 {
if _, err := tee.Write(zero16[:16-padding]); err != nil {
return err
}
}
// write frame MAC. egress MAC hash is up to date because
// frame content was written to it as well.
fmacseed := h.egressMAC.Sum(nil)
mac := updateMAC(h.egressMAC, h.macCipher, fmacseed)
_, err := conn.Write(mac)
return err
}
func readInt24(b []byte) uint32 {
return uint32(b[2]) | uint32(b[1])<<8 | uint32(b[0])<<16
}
func putInt24(v uint32, b []byte) {
b[0] = byte(v >> 16)
b[1] = byte(v >> 8)
b[2] = byte(v)
}
// updateMAC reseeds the given hash with encrypted seed.
// it returns the first 16 bytes of the hash sum after seeding.
func updateMAC(mac hash.Hash, block cipher.Block, seed []byte) []byte {
aesbuf := make([]byte, aes.BlockSize)
block.Encrypt(aesbuf, mac.Sum(nil))
for i := range aesbuf {
aesbuf[i] ^= seed[i]
}
mac.Write(aesbuf)
return mac.Sum(nil)[:16]
}
// Handshake performs the handshake. This must be called before any data is written
// or read from the connection.
func (c *Conn) Handshake(prv *ecdsa.PrivateKey) (*ecdsa.PublicKey, error) {
var (
sec Secrets
err error
)
if c.dialDest != nil {
sec, err = initiatorEncHandshake(c.conn, prv, c.dialDest)
} else {
sec, err = receiverEncHandshake(c.conn, prv)
}
if err != nil {
return nil, err
}
c.InitWithSecrets(sec)
return sec.remote, err
}
// InitWithSecrets injects connection secrets as if a handshake had
// been performed. This cannot be called after the handshake.
func (c *Conn) InitWithSecrets(sec Secrets) {
if c.handshake != nil {
panic("can't handshake twice")
}
macc, err := aes.NewCipher(sec.MAC)
if err != nil {
panic("invalid MAC secret: " + err.Error())
}
encc, err := aes.NewCipher(sec.AES)
if err != nil {
panic("invalid AES secret: " + err.Error())
}
// we use an all-zeroes IV for AES because the key used
// for encryption is ephemeral.
iv := make([]byte, encc.BlockSize())
c.handshake = &handshakeState{
enc: cipher.NewCTR(encc, iv),
dec: cipher.NewCTR(encc, iv),
macCipher: macc,
egressMAC: sec.EgressMAC,
ingressMAC: sec.IngressMAC,
}
}
// Close closes the underlying network connection.
func (c *Conn) Close() error {
return c.conn.Close()
}
// Constants for the handshake.
const (
maxUint24 = int(^uint32(0) >> 8)
sskLen = 16 // ecies.MaxSharedKeyLength(pubKey) / 2
sigLen = crypto.SignatureLength // elliptic S256
pubLen = 64 // 512 bit pubkey in uncompressed representation without format byte
shaLen = 32 // hash length (for nonce etc)
authMsgLen = sigLen + shaLen + pubLen + shaLen + 1
authRespLen = pubLen + shaLen + 1
eciesOverhead = 65 /* pubkey */ + 16 /* IV */ + 32 /* MAC */
encAuthMsgLen = authMsgLen + eciesOverhead // size of encrypted pre-EIP-8 initiator handshake
encAuthRespLen = authRespLen + eciesOverhead // size of encrypted pre-EIP-8 handshake reply
)
var (
// this is used in place of actual frame header data.
// TODO: replace this when Msg contains the protocol type code.
zeroHeader = []byte{0xC2, 0x80, 0x80}
// sixteen zero bytes
zero16 = make([]byte, 16)
// errPlainMessageTooLarge is returned if a decompressed message length exceeds
// the allowed 24 bits (i.e. length >= 16MB).
errPlainMessageTooLarge = errors.New("message length >= 16MB")
)
// Secrets represents the connection secrets which are negotiated during the handshake.
type Secrets struct {
AES, MAC []byte
EgressMAC, IngressMAC hash.Hash
remote *ecdsa.PublicKey
}
// encHandshake contains the state of the encryption handshake.
type encHandshake struct {
initiator bool
remote *ecies.PublicKey // remote-pubk
initNonce, respNonce []byte // nonce
randomPrivKey *ecies.PrivateKey // ecdhe-random
remoteRandomPub *ecies.PublicKey // ecdhe-random-pubk
}
// RLPx v4 handshake auth (defined in EIP-8).
type authMsgV4 struct {
gotPlain bool // whether read packet had plain format.
Signature [sigLen]byte
InitiatorPubkey [pubLen]byte
Nonce [shaLen]byte
Version uint
// Ignore additional fields (forward-compatibility)
Rest []rlp.RawValue `rlp:"tail"`
}
// RLPx v4 handshake response (defined in EIP-8).
type authRespV4 struct {
RandomPubkey [pubLen]byte
Nonce [shaLen]byte
Version uint
// Ignore additional fields (forward-compatibility)
Rest []rlp.RawValue `rlp:"tail"`
}
// receiverEncHandshake negotiates a session token on conn.
// it should be called on the listening side of the connection.
//
// prv is the local client's private key.
func receiverEncHandshake(conn io.ReadWriter, prv *ecdsa.PrivateKey) (s Secrets, err error) {
authMsg := new(authMsgV4)
authPacket, err := readHandshakeMsg(authMsg, encAuthMsgLen, prv, conn)
if err != nil {
return s, err
}
h := new(encHandshake)
if err := h.handleAuthMsg(authMsg, prv); err != nil {
return s, err
}
authRespMsg, err := h.makeAuthResp()
if err != nil {
return s, err
}
var authRespPacket []byte
if authMsg.gotPlain {
authRespPacket, err = authRespMsg.sealPlain(h)
} else {
authRespPacket, err = sealEIP8(authRespMsg, h)
}
if err != nil {
return s, err
}
if _, err = conn.Write(authRespPacket); err != nil {
return s, err
}
return h.secrets(authPacket, authRespPacket)
}
func (h *encHandshake) handleAuthMsg(msg *authMsgV4, prv *ecdsa.PrivateKey) error {
// Import the remote identity.
rpub, err := importPublicKey(msg.InitiatorPubkey[:])
if err != nil {
return err
}
h.initNonce = msg.Nonce[:]
h.remote = rpub
// Generate random keypair for ECDH.
// If a private key is already set, use it instead of generating one (for testing).
if h.randomPrivKey == nil {
h.randomPrivKey, err = ecies.GenerateKey(rand.Reader, crypto.S256(), nil)
if err != nil {
return err
}
}
// Check the signature.
token, err := h.staticSharedSecret(prv)
if err != nil {
return err
}
signedMsg := xor(token, h.initNonce)
remoteRandomPub, err := crypto.Ecrecover(signedMsg, msg.Signature[:])
if err != nil {
return err
}
h.remoteRandomPub, _ = importPublicKey(remoteRandomPub)
return nil
}
// secrets is called after the handshake is completed.
// It extracts the connection secrets from the handshake values.
func (h *encHandshake) secrets(auth, authResp []byte) (Secrets, error) {
ecdheSecret, err := h.randomPrivKey.GenerateShared(h.remoteRandomPub, sskLen, sskLen)
if err != nil {
return Secrets{}, err
}
// derive base secrets from ephemeral key agreement
sharedSecret := crypto.Keccak256(ecdheSecret, crypto.Keccak256(h.respNonce, h.initNonce))
aesSecret := crypto.Keccak256(ecdheSecret, sharedSecret)
s := Secrets{
remote: h.remote.ExportECDSA(),
AES: aesSecret,
MAC: crypto.Keccak256(ecdheSecret, aesSecret),
}
// setup sha3 instances for the MACs
mac1 := sha3.NewLegacyKeccak256()
mac1.Write(xor(s.MAC, h.respNonce))
mac1.Write(auth)
mac2 := sha3.NewLegacyKeccak256()
mac2.Write(xor(s.MAC, h.initNonce))
mac2.Write(authResp)
if h.initiator {
s.EgressMAC, s.IngressMAC = mac1, mac2
} else {
s.EgressMAC, s.IngressMAC = mac2, mac1
}
return s, nil
}
// staticSharedSecret returns the static shared secret, the result
// of key agreement between the local and remote static node key.
func (h *encHandshake) staticSharedSecret(prv *ecdsa.PrivateKey) ([]byte, error) {
return ecies.ImportECDSA(prv).GenerateShared(h.remote, sskLen, sskLen)
}
// initiatorEncHandshake negotiates a session token on conn.
// it should be called on the dialing side of the connection.
//
// prv is the local client's private key.
func initiatorEncHandshake(conn io.ReadWriter, prv *ecdsa.PrivateKey, remote *ecdsa.PublicKey) (s Secrets, err error) {
h := &encHandshake{initiator: true, remote: ecies.ImportECDSAPublic(remote)}
authMsg, err := h.makeAuthMsg(prv)
if err != nil {
return s, err
}
authPacket, err := sealEIP8(authMsg, h)
if err != nil {
return s, err
}
if _, err = conn.Write(authPacket); err != nil {
return s, err
}
authRespMsg := new(authRespV4)
authRespPacket, err := readHandshakeMsg(authRespMsg, encAuthRespLen, prv, conn)
if err != nil {
return s, err
}
if err := h.handleAuthResp(authRespMsg); err != nil {
return s, err
}
return h.secrets(authPacket, authRespPacket)
}
// makeAuthMsg creates the initiator handshake message.
func (h *encHandshake) makeAuthMsg(prv *ecdsa.PrivateKey) (*authMsgV4, error) {
// Generate random initiator nonce.
h.initNonce = make([]byte, shaLen)
_, err := rand.Read(h.initNonce)
if err != nil {
return nil, err
}
// Generate random keypair to for ECDH.
h.randomPrivKey, err = ecies.GenerateKey(rand.Reader, crypto.S256(), nil)
if err != nil {
return nil, err
}
// Sign known message: static-shared-secret ^ nonce
token, err := h.staticSharedSecret(prv)
if err != nil {
return nil, err
}
signed := xor(token, h.initNonce)
signature, err := crypto.Sign(signed, h.randomPrivKey.ExportECDSA())
if err != nil {
return nil, err
}
msg := new(authMsgV4)
copy(msg.Signature[:], signature)
copy(msg.InitiatorPubkey[:], crypto.FromECDSAPub(&prv.PublicKey)[1:])
copy(msg.Nonce[:], h.initNonce)
msg.Version = 4
return msg, nil
}
func (h *encHandshake) handleAuthResp(msg *authRespV4) (err error) {
h.respNonce = msg.Nonce[:]
h.remoteRandomPub, err = importPublicKey(msg.RandomPubkey[:])
return err
}
func (h *encHandshake) makeAuthResp() (msg *authRespV4, err error) {
// Generate random nonce.
h.respNonce = make([]byte, shaLen)
if _, err = rand.Read(h.respNonce); err != nil {
return nil, err
}
msg = new(authRespV4)
copy(msg.Nonce[:], h.respNonce)
copy(msg.RandomPubkey[:], exportPubkey(&h.randomPrivKey.PublicKey))
msg.Version = 4
return msg, nil
}
func (msg *authMsgV4) decodePlain(input []byte) {
n := copy(msg.Signature[:], input)
n += shaLen // skip sha3(initiator-ephemeral-pubk)
n += copy(msg.InitiatorPubkey[:], input[n:])
copy(msg.Nonce[:], input[n:])
msg.Version = 4
msg.gotPlain = true
}
func (msg *authRespV4) sealPlain(hs *encHandshake) ([]byte, error) {
buf := make([]byte, authRespLen)
n := copy(buf, msg.RandomPubkey[:])
copy(buf[n:], msg.Nonce[:])
return ecies.Encrypt(rand.Reader, hs.remote, buf, nil, nil)
}
func (msg *authRespV4) decodePlain(input []byte) {
n := copy(msg.RandomPubkey[:], input)
copy(msg.Nonce[:], input[n:])
msg.Version = 4
}
var padSpace = make([]byte, 300)
func sealEIP8(msg interface{}, h *encHandshake) ([]byte, error) {
buf := new(bytes.Buffer)
if err := rlp.Encode(buf, msg); err != nil {
return nil, err
}
// pad with random amount of data. the amount needs to be at least 100 bytes to make
// the message distinguishable from pre-EIP-8 handshakes.
pad := padSpace[:mrand.Intn(len(padSpace)-100)+100]
buf.Write(pad)
prefix := make([]byte, 2)
binary.BigEndian.PutUint16(prefix, uint16(buf.Len()+eciesOverhead))
enc, err := ecies.Encrypt(rand.Reader, h.remote, buf.Bytes(), nil, prefix)
return append(prefix, enc...), err
}
type plainDecoder interface {
decodePlain([]byte)
}
func readHandshakeMsg(msg plainDecoder, plainSize int, prv *ecdsa.PrivateKey, r io.Reader) ([]byte, error) {
buf := make([]byte, plainSize)
if _, err := io.ReadFull(r, buf); err != nil {
return buf, err
}
// Attempt decoding pre-EIP-8 "plain" format.
key := ecies.ImportECDSA(prv)
if dec, err := key.Decrypt(buf, nil, nil); err == nil {
msg.decodePlain(dec)
return buf, nil
}
// Could be EIP-8 format, try that.
prefix := buf[:2]
size := binary.BigEndian.Uint16(prefix)
if size < uint16(plainSize) {
return buf, fmt.Errorf("size underflow, need at least %d bytes", plainSize)
}
buf = append(buf, make([]byte, size-uint16(plainSize)+2)...)
if _, err := io.ReadFull(r, buf[plainSize:]); err != nil {
return buf, err
}
dec, err := key.Decrypt(buf[2:], nil, prefix)
if err != nil {
return buf, err
}
// Can't use rlp.DecodeBytes here because it rejects
// trailing data (forward-compatibility).
s := rlp.NewStream(bytes.NewReader(dec), 0)
return buf, s.Decode(msg)
}
// importPublicKey unmarshals 512 bit public keys.
func importPublicKey(pubKey []byte) (*ecies.PublicKey, error) {
var pubKey65 []byte
switch len(pubKey) {
case 64:
// add 'uncompressed key' flag
pubKey65 = append([]byte{0x04}, pubKey...)
case 65:
pubKey65 = pubKey
default:
return nil, fmt.Errorf("invalid public key length %v (expect 64/65)", len(pubKey))
}
// TODO: fewer pointless conversions
pub, err := crypto.UnmarshalPubkey(pubKey65)
if err != nil {
return nil, err
}
return ecies.ImportECDSAPublic(pub), nil
}
func exportPubkey(pub *ecies.PublicKey) []byte {
if pub == nil {
panic("nil pubkey")
}
return elliptic.Marshal(pub.Curve, pub.X, pub.Y)[1:]
}
func xor(one, other []byte) (xor []byte) {
xor = make([]byte, len(one))
for i := 0; i < len(one); i++ {
xor[i] = one[i] ^ other[i]
}
return xor
}