p2p: add basic RLPx frame I/O

This commit is contained in:
Felix Lange 2015-02-26 22:30:34 +00:00
parent 15f491e500
commit 936dd0f3bc
2 changed files with 252 additions and 0 deletions

129
p2p/rlpx.go Normal file
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@ -0,0 +1,129 @@
package p2p
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/hmac"
"errors"
"hash"
"io"
"github.com/ethereum/go-ethereum/rlp"
)
var (
zeroHeader = []byte{0xC2, 0x80, 0x80}
zero16 = make([]byte, 16)
)
type rlpxFrameRW struct {
conn io.ReadWriter
macCipher cipher.Block
egressMAC hash.Hash
ingressMAC hash.Hash
}
func newRlpxFrameRW(conn io.ReadWriter, macSecret []byte, egressMAC, ingressMAC hash.Hash) *rlpxFrameRW {
cipher, err := aes.NewCipher(macSecret)
if err != nil {
panic("invalid macSecret: " + err.Error())
}
return &rlpxFrameRW{conn: conn, macCipher: cipher, egressMAC: egressMAC, ingressMAC: ingressMAC}
}
func (rw *rlpxFrameRW) WriteMsg(msg Msg) error {
ptype, _ := rlp.EncodeToBytes(msg.Code)
// write header
headbuf := make([]byte, 32)
fsize := uint32(len(ptype)) + msg.Size
putInt24(fsize, headbuf) // TODO: check overflow
copy(headbuf[3:], zeroHeader)
copy(headbuf[16:], updateHeaderMAC(rw.egressMAC, rw.macCipher, headbuf[:16]))
if _, err := rw.conn.Write(headbuf); err != nil {
return err
}
// write frame, updating the egress MAC while writing to conn.
tee := io.MultiWriter(rw.conn, rw.egressMAC)
if _, err := tee.Write(ptype); err != nil {
return err
}
if _, err := io.Copy(tee, msg.Payload); err != nil {
return err
}
if padding := fsize % 16; padding > 0 {
if _, err := tee.Write(zero16[:16-padding]); err != nil {
return err
}
}
// write packet-mac. egress MAC is up to date because
// frame content was written to it as well.
_, err := rw.conn.Write(rw.egressMAC.Sum(nil))
return err
}
func (rw *rlpxFrameRW) ReadMsg() (msg Msg, err error) {
// read the header
headbuf := make([]byte, 32)
if _, err := io.ReadFull(rw.conn, headbuf); err != nil {
return msg, err
}
fsize := readInt24(headbuf)
// ignore protocol type for now
shouldMAC := updateHeaderMAC(rw.ingressMAC, rw.macCipher, headbuf[:16])
if !hmac.Equal(shouldMAC[:16], headbuf[16:]) {
return msg, errors.New("bad header MAC")
}
// read the frame content
framebuf := make([]byte, fsize)
if _, err := io.ReadFull(rw.conn, framebuf); err != nil {
return msg, err
}
rw.ingressMAC.Write(framebuf)
if padding := fsize % 16; padding > 0 {
if _, err := io.CopyN(rw.ingressMAC, rw.conn, int64(16-padding)); err != nil {
return msg, err
}
}
// read and validate frame MAC. we can re-use headbuf for that.
if _, err := io.ReadFull(rw.conn, headbuf); err != nil {
return msg, err
}
if !hmac.Equal(rw.ingressMAC.Sum(nil), headbuf) {
return msg, errors.New("bad frame MAC")
}
// decode message code
content := bytes.NewReader(framebuf)
if err := rlp.Decode(content, &msg.Code); err != nil {
return msg, err
}
msg.Size = uint32(content.Len())
msg.Payload = content
return msg, nil
}
func updateHeaderMAC(mac hash.Hash, block cipher.Block, header []byte) []byte {
aesbuf := make([]byte, aes.BlockSize)
block.Encrypt(aesbuf, mac.Sum(nil))
for i := range aesbuf {
aesbuf[i] ^= header[i]
}
mac.Write(aesbuf)
return mac.Sum(nil)
}
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)
}

123
p2p/rlpx_test.go Normal file
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package p2p
import (
"bytes"
"crypto/rand"
"encoding/hex"
"fmt"
"io/ioutil"
"strings"
"testing"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/crypto/sha3"
"github.com/ethereum/go-ethereum/rlp"
)
func TestRlpxFrameFake(t *testing.T) {
buf := new(bytes.Buffer)
secret := crypto.Sha3()
hash := fakeHash([]byte{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1})
rw := newRlpxFrameRW(buf, secret, hash, hash)
golden := unhex(`
000006C2808000000000000000000000
01010101010101010101010101010101
08C40102030400000000000000000000
01010101010101010101010101010101
01010101010101010101010101010101
`)
// Check WriteMsg. This puts a message into the buffer.
if err := EncodeMsg(rw, 8, []interface{}{1, 2, 3, 4}); err != nil {
t.Fatalf("WriteMsg error: %v", err)
}
written := buf.Bytes()
if !bytes.Equal(written, golden) {
t.Fatalf("output mismatch:\n got: %x\n want: %x", written, golden)
}
// Check ReadMsg. It reads the message encoded by WriteMsg, which
// is equivalent to the golden message above.
msg, err := rw.ReadMsg()
if err != nil {
t.Fatalf("ReadMsg error: %v", err)
}
if msg.Size != 5 {
t.Errorf("msg size mismatch: got %d, want %d", msg.Size, 5)
}
if msg.Code != 8 {
t.Errorf("msg code mismatch: got %d, want %d", msg.Code, 8)
}
payload, _ := ioutil.ReadAll(msg.Payload)
wantPayload := unhex("C401020304")
if !bytes.Equal(payload, wantPayload) {
t.Errorf("msg payload mismatch:\ngot %x\nwant %x", payload, wantPayload)
}
}
type fakeHash []byte
func (fakeHash) Write(p []byte) (int, error) { return len(p), nil }
func (fakeHash) Reset() {}
func (fakeHash) BlockSize() int { return 0 }
func (h fakeHash) Size() int { return len(h) }
func (h fakeHash) Sum(b []byte) []byte { return append(b, h...) }
func unhex(str string) []byte {
b, err := hex.DecodeString(strings.Replace(str, "\n", "", -1))
if err != nil {
panic(fmt.Sprintf("invalid hex string: %q", str))
}
return b
}
func TestRlpxFrameRW(t *testing.T) {
var (
macSecret = make([]byte, 16)
egressMACinit = make([]byte, 32)
ingressMACinit = make([]byte, 32)
)
for _, s := range [][]byte{macSecret, egressMACinit, ingressMACinit} {
rand.Read(s)
}
conn := new(bytes.Buffer)
em1 := sha3.NewKeccak256()
em1.Write(egressMACinit)
im1 := sha3.NewKeccak256()
im1.Write(ingressMACinit)
rw1 := newRlpxFrameRW(conn, macSecret, em1, im1)
em2 := sha3.NewKeccak256()
em2.Write(ingressMACinit)
im2 := sha3.NewKeccak256()
im2.Write(egressMACinit)
rw2 := newRlpxFrameRW(conn, macSecret, em2, im2)
// send some messages
for i := 0; i < 10; i++ {
// write message into conn buffer
wmsg := []interface{}{"foo", "bar", strings.Repeat("test", i)}
err := EncodeMsg(rw1, uint64(i), wmsg)
if err != nil {
t.Fatalf("WriteMsg error (i=%d): %v", i, err)
}
// read message that rw1 just wrote
msg, err := rw2.ReadMsg()
if err != nil {
t.Fatalf("ReadMsg error (i=%d): %v", i, err)
}
if msg.Code != uint64(i) {
t.Fatalf("msg code mismatch: got %d, want %d", msg.Code, i)
}
payload, _ := ioutil.ReadAll(msg.Payload)
wantPayload, _ := rlp.EncodeToBytes(wmsg)
if !bytes.Equal(payload, wantPayload) {
t.Fatalf("msg payload mismatch:\ngot %x\nwant %x", payload, wantPayload)
}
}
}