1 files changed, 440 insertions, 4 deletions

diff --git a/p2p/rlpx.go b/p2p/rlpx.go
index 6b533e275..e1cb13aae 100644
--- a/p2p/rlpx.go
+++ b/p2p/rlpx.go
@@ -4,23 +4,459 @@ import (
 	"bytes"
 	"crypto/aes"
 	"crypto/cipher"
+	"crypto/ecdsa"
+	"crypto/elliptic"
 	"crypto/hmac"
+	"crypto/rand"
 	"errors"
+	"fmt"
 	"hash"
 	"io"
+	"net"
+	"sync"
+	"time"
 
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/crypto/ecies"
+	"github.com/ethereum/go-ethereum/crypto/secp256k1"
+	"github.com/ethereum/go-ethereum/crypto/sha3"
+	"github.com/ethereum/go-ethereum/p2p/discover"
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
+const (
+	maxUint24 = ^uint32(0) >> 8
+
+	sskLen = 16 // ecies.MaxSharedKeyLength(pubKey) / 2
+	sigLen = 65 // 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
+
+	eciesBytes     = 65 + 16 + 32
+	encAuthMsgLen  = authMsgLen + eciesBytes  // size of the final ECIES payload sent as initiator's handshake
+	encAuthRespLen = authRespLen + eciesBytes // size of the final ECIES payload sent as receiver's handshake
+
+	// total timeout for encryption handshake and protocol
+	// handshake in both directions.
+	handshakeTimeout = 5 * time.Second
+
+	// This is the timeout for sending the disconnect reason.
+	// This is shorter than the usual timeout because we don't want
+	// to wait if the connection is known to be bad anyway.
+	discWriteTimeout = 1 * time.Second
+)
+
+// rlpx is the transport protocol used by actual (non-test) connections.
+// It wraps the frame encoder with locks and read/write deadlines.
+type rlpx struct {
+	fd net.Conn
+
+	rmu, wmu sync.Mutex
+	rw       *rlpxFrameRW
+}
+
+func newRLPX(fd net.Conn) transport {
+	fd.SetDeadline(time.Now().Add(handshakeTimeout))
+	return &rlpx{fd: fd}
+}
+
+func (t *rlpx) ReadMsg() (Msg, error) {
+	t.rmu.Lock()
+	defer t.rmu.Unlock()
+	t.fd.SetReadDeadline(time.Now().Add(frameReadTimeout))
+	return t.rw.ReadMsg()
+}
+
+func (t *rlpx) WriteMsg(msg Msg) error {
+	t.wmu.Lock()
+	defer t.wmu.Unlock()
+	t.fd.SetWriteDeadline(time.Now().Add(frameWriteTimeout))
+	return t.rw.WriteMsg(msg)
+}
+
+func (t *rlpx) close(err error) {
+	t.wmu.Lock()
+	defer t.wmu.Unlock()
+	// Tell the remote end why we're disconnecting if possible.
+	if t.rw != nil {
+		if r, ok := err.(DiscReason); ok && r != DiscNetworkError {
+			t.fd.SetWriteDeadline(time.Now().Add(discWriteTimeout))
+			SendItems(t.rw, discMsg, r)
+		}
+	}
+	t.fd.Close()
+}
+
+// doEncHandshake runs the protocol handshake using authenticated
+// messages. the protocol handshake is the first authenticated message
+// and also verifies whether the encryption handshake 'worked' and the
+// remote side actually provided the right public key.
+func (t *rlpx) doProtoHandshake(our *protoHandshake) (their *protoHandshake, err error) {
+	// Writing our handshake happens concurrently, we prefer
+	// returning the handshake read error. If the remote side
+	// disconnects us early with a valid reason, we should return it
+	// as the error so it can be tracked elsewhere.
+	werr := make(chan error, 1)
+	go func() { werr <- Send(t.rw, handshakeMsg, our) }()
+	if their, err = readProtocolHandshake(t.rw, our); err != nil {
+		return nil, err
+	}
+	if err := <-werr; err != nil {
+		return nil, fmt.Errorf("write error: %v", err)
+	}
+	return their, nil
+}
+
+func readProtocolHandshake(rw MsgReader, our *protoHandshake) (*protoHandshake, error) {
+	msg, err := rw.ReadMsg()
+	if err != nil {
+		return nil, err
+	}
+	if msg.Size > baseProtocolMaxMsgSize {
+		return nil, fmt.Errorf("message too big")
+	}
+	if msg.Code == discMsg {
+		// Disconnect before protocol handshake is valid according to the
+		// spec and we send it ourself if the posthanshake checks fail.
+		// We can't return the reason directly, though, because it is echoed
+		// back otherwise. Wrap it in a string instead.
+		var reason [1]DiscReason
+		rlp.Decode(msg.Payload, &reason)
+		return nil, reason[0]
+	}
+	if msg.Code != handshakeMsg {
+		return nil, fmt.Errorf("expected handshake, got %x", msg.Code)
+	}
+	var hs protoHandshake
+	if err := msg.Decode(&hs); err != nil {
+		return nil, err
+	}
+	// validate handshake info
+	if hs.Version != our.Version {
+		return nil, DiscIncompatibleVersion
+	}
+	if (hs.ID == discover.NodeID{}) {
+		return nil, DiscInvalidIdentity
+	}
+	return &hs, nil
+}
+
+func (t *rlpx) doEncHandshake(prv *ecdsa.PrivateKey, dial *discover.Node) (discover.NodeID, error) {
+	var (
+		sec secrets
+		err error
+	)
+	if dial == nil {
+		sec, err = receiverEncHandshake(t.fd, prv, nil)
+	} else {
+		sec, err = initiatorEncHandshake(t.fd, prv, dial.ID, nil)
+	}
+	if err != nil {
+		return discover.NodeID{}, err
+	}
+	t.wmu.Lock()
+	t.rw = newRLPXFrameRW(t.fd, sec)
+	t.wmu.Unlock()
+	return sec.RemoteID, nil
+}
+
+// encHandshake contains the state of the encryption handshake.
+type encHandshake struct {
+	initiator bool
+	remoteID  discover.NodeID
+
+	remotePub            *ecies.PublicKey  // remote-pubk
+	initNonce, respNonce []byte            // nonce
+	randomPrivKey        *ecies.PrivateKey // ecdhe-random
+	remoteRandomPub      *ecies.PublicKey  // ecdhe-random-pubk
+}
+
+// secrets represents the connection secrets
+// which are negotiated during the encryption handshake.
+type secrets struct {
+	RemoteID              discover.NodeID
+	AES, MAC              []byte
+	EgressMAC, IngressMAC hash.Hash
+	Token                 []byte
+}
+
+// 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.Sha3(ecdheSecret, crypto.Sha3(h.respNonce, h.initNonce))
+	aesSecret := crypto.Sha3(ecdheSecret, sharedSecret)
+	s := secrets{
+		RemoteID: h.remoteID,
+		AES:      aesSecret,
+		MAC:      crypto.Sha3(ecdheSecret, aesSecret),
+		Token:    crypto.Sha3(sharedSecret),
+	}
+
+	// setup sha3 instances for the MACs
+	mac1 := sha3.NewKeccak256()
+	mac1.Write(xor(s.MAC, h.respNonce))
+	mac1.Write(auth)
+	mac2 := sha3.NewKeccak256()
+	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
+}
+
+func (h *encHandshake) ecdhShared(prv *ecdsa.PrivateKey) ([]byte, error) {
+	return ecies.ImportECDSA(prv).GenerateShared(h.remotePub, 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.
+// token is the token from a previous session with this node.
+func initiatorEncHandshake(conn io.ReadWriter, prv *ecdsa.PrivateKey, remoteID discover.NodeID, token []byte) (s secrets, err error) {
+	h, err := newInitiatorHandshake(remoteID)
+	if err != nil {
+		return s, err
+	}
+	auth, err := h.authMsg(prv, token)
+	if err != nil {
+		return s, err
+	}
+	if _, err = conn.Write(auth); err != nil {
+		return s, err
+	}
+
+	response := make([]byte, encAuthRespLen)
+	if _, err = io.ReadFull(conn, response); err != nil {
+		return s, err
+	}
+	if err := h.decodeAuthResp(response, prv); err != nil {
+		return s, err
+	}
+	return h.secrets(auth, response)
+}
+
+func newInitiatorHandshake(remoteID discover.NodeID) (*encHandshake, error) {
+	// generate random initiator nonce
+	n := make([]byte, shaLen)
+	if _, err := rand.Read(n); err != nil {
+		return nil, err
+	}
+	// generate random keypair to use for signing
+	randpriv, err := ecies.GenerateKey(rand.Reader, crypto.S256(), nil)
+	if err != nil {
+		return nil, err
+	}
+	rpub, err := remoteID.Pubkey()
+	if err != nil {
+		return nil, fmt.Errorf("bad remoteID: %v", err)
+	}
+	h := &encHandshake{
+		initiator:     true,
+		remoteID:      remoteID,
+		remotePub:     ecies.ImportECDSAPublic(rpub),
+		initNonce:     n,
+		randomPrivKey: randpriv,
+	}
+	return h, nil
+}
+
+// authMsg creates an encrypted initiator handshake message.
+func (h *encHandshake) authMsg(prv *ecdsa.PrivateKey, token []byte) ([]byte, error) {
+	var tokenFlag byte
+	if token == nil {
+		// no session token found means we need to generate shared secret.
+		// ecies shared secret is used as initial session token for new peers
+		// generate shared key from prv and remote pubkey
+		var err error
+		if token, err = h.ecdhShared(prv); err != nil {
+			return nil, err
+		}
+	} else {
+		// for known peers, we use stored token from the previous session
+		tokenFlag = 0x01
+	}
+
+	// sign known message:
+	//   ecdh-shared-secret^nonce for new peers
+	//   token^nonce for old peers
+	signed := xor(token, h.initNonce)
+	signature, err := crypto.Sign(signed, h.randomPrivKey.ExportECDSA())
+	if err != nil {
+		return nil, err
+	}
+
+	// encode auth message
+	// signature || sha3(ecdhe-random-pubk) || pubk || nonce || token-flag
+	msg := make([]byte, authMsgLen)
+	n := copy(msg, signature)
+	n += copy(msg[n:], crypto.Sha3(exportPubkey(&h.randomPrivKey.PublicKey)))
+	n += copy(msg[n:], crypto.FromECDSAPub(&prv.PublicKey)[1:])
+	n += copy(msg[n:], h.initNonce)
+	msg[n] = tokenFlag
+
+	// encrypt auth message using remote-pubk
+	return ecies.Encrypt(rand.Reader, h.remotePub, msg, nil, nil)
+}
+
+// decodeAuthResp decode an encrypted authentication response message.
+func (h *encHandshake) decodeAuthResp(auth []byte, prv *ecdsa.PrivateKey) error {
+	msg, err := crypto.Decrypt(prv, auth)
+	if err != nil {
+		return fmt.Errorf("could not decrypt auth response (%v)", err)
+	}
+	h.respNonce = msg[pubLen : pubLen+shaLen]
+	h.remoteRandomPub, err = importPublicKey(msg[:pubLen])
+	if err != nil {
+		return err
+	}
+	// ignore token flag for now
+	return nil
+}
+
+// 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.
+// token is the token from a previous session with this node.
+func receiverEncHandshake(conn io.ReadWriter, prv *ecdsa.PrivateKey, token []byte) (s secrets, err error) {
+	// read remote auth sent by initiator.
+	auth := make([]byte, encAuthMsgLen)
+	if _, err := io.ReadFull(conn, auth); err != nil {
+		return s, err
+	}
+	h, err := decodeAuthMsg(prv, token, auth)
+	if err != nil {
+		return s, err
+	}
+
+	// send auth response
+	resp, err := h.authResp(prv, token)
+	if err != nil {
+		return s, err
+	}
+	if _, err = conn.Write(resp); err != nil {
+		return s, err
+	}
+
+	return h.secrets(auth, resp)
+}
+
+func decodeAuthMsg(prv *ecdsa.PrivateKey, token []byte, auth []byte) (*encHandshake, error) {
+	var err error
+	h := new(encHandshake)
+	// generate random keypair for session
+	h.randomPrivKey, err = ecies.GenerateKey(rand.Reader, crypto.S256(), nil)
+	if err != nil {
+		return nil, err
+	}
+	// generate random nonce
+	h.respNonce = make([]byte, shaLen)
+	if _, err = rand.Read(h.respNonce); err != nil {
+		return nil, err
+	}
+
+	msg, err := crypto.Decrypt(prv, auth)
+	if err != nil {
+		return nil, fmt.Errorf("could not decrypt auth message (%v)", err)
+	}
+
+	// decode message parameters
+	// signature || sha3(ecdhe-random-pubk) || pubk || nonce || token-flag
+	h.initNonce = msg[authMsgLen-shaLen-1 : authMsgLen-1]
+	copy(h.remoteID[:], msg[sigLen+shaLen:sigLen+shaLen+pubLen])
+	rpub, err := h.remoteID.Pubkey()
+	if err != nil {
+		return nil, fmt.Errorf("bad remoteID: %#v", err)
+	}
+	h.remotePub = ecies.ImportECDSAPublic(rpub)
+
+	// recover remote random pubkey from signed message.
+	if token == nil {
+		// TODO: it is an error if the initiator has a token and we don't. check that.
+
+		// no session token means we need to generate shared secret.
+		// ecies shared secret is used as initial session token for new peers.
+		// generate shared key from prv and remote pubkey.
+		if token, err = h.ecdhShared(prv); err != nil {
+			return nil, err
+		}
+	}
+	signedMsg := xor(token, h.initNonce)
+	remoteRandomPub, err := secp256k1.RecoverPubkey(signedMsg, msg[:sigLen])
+	if err != nil {
+		return nil, err
+	}
+	h.remoteRandomPub, _ = importPublicKey(remoteRandomPub)
+	return h, nil
+}
+
+// authResp generates the encrypted authentication response message.
+func (h *encHandshake) authResp(prv *ecdsa.PrivateKey, token []byte) ([]byte, error) {
+	// responder auth message
+	// E(remote-pubk, ecdhe-random-pubk || nonce || 0x0)
+	resp := make([]byte, authRespLen)
+	n := copy(resp, exportPubkey(&h.randomPrivKey.PublicKey))
+	n += copy(resp[n:], h.respNonce)
+	if token == nil {
+		resp[n] = 0
+	} else {
+		resp[n] = 1
+	}
+	// encrypt using remote-pubk
+	return ecies.Encrypt(rand.Reader, h.remotePub, resp, nil, nil)
+}
+
+// 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
+	return ecies.ImportECDSAPublic(crypto.ToECDSAPub(pubKey65)), 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
+}
+
 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)
-
-	maxUint24 = ^uint32(0) >> 8
 )
 
 // rlpxFrameRW implements a simplified version of RLPx framing.
@@ -38,7 +474,7 @@ type rlpxFrameRW struct {
 	ingressMAC hash.Hash
 }
 
-func newRlpxFrameRW(conn io.ReadWriter, s secrets) *rlpxFrameRW {
+func newRLPXFrameRW(conn io.ReadWriter, s secrets) *rlpxFrameRW {
 	macc, err := aes.NewCipher(s.MAC)
 	if err != nil {
 		panic("invalid MAC secret: " + err.Error())