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path: root/p2p/rlpx.go
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Diffstat (limited to 'p2p/rlpx.go')
-rw-r--r--p2p/rlpx.go31
1 files changed, 19 insertions, 12 deletions
diff --git a/p2p/rlpx.go b/p2p/rlpx.go
index 761dc2ed9..a041bb314 100644
--- a/p2p/rlpx.go
+++ b/p2p/rlpx.go
@@ -62,12 +62,15 @@ func (rw *rlpxFrameRW) WriteMsg(msg Msg) error {
putInt24(fsize, headbuf) // TODO: check overflow
copy(headbuf[3:], zeroHeader)
rw.enc.XORKeyStream(headbuf[:16], headbuf[:16]) // first half is now encrypted
- copy(headbuf[16:], updateHeaderMAC(rw.egressMAC, rw.macCipher, headbuf[:16]))
+
+ // write header MAC
+ copy(headbuf[16:], updateMAC(rw.egressMAC, rw.macCipher, headbuf[:16]))
if _, err := rw.conn.Write(headbuf); err != nil {
return err
}
- // write encrypted frame, updating the egress MAC while writing to conn.
+ // write encrypted frame, updating the egress MAC hash with
+ // the data written to conn.
tee := cipher.StreamWriter{S: rw.enc, W: io.MultiWriter(rw.conn, rw.egressMAC)}
if _, err := tee.Write(ptype); err != nil {
return err
@@ -81,9 +84,10 @@ func (rw *rlpxFrameRW) WriteMsg(msg Msg) error {
}
}
- // write packet-mac. egress MAC is up to date because
+ // write frame MAC. egress MAC hash is up to date because
// frame content was written to it as well.
- mac := updateHeaderMAC(rw.egressMAC, rw.macCipher, rw.egressMAC.Sum(nil))
+ fmacseed := rw.egressMAC.Sum(nil)
+ mac := updateMAC(rw.egressMAC, rw.macCipher, fmacseed)
_, err := rw.conn.Write(mac)
return err
}
@@ -95,8 +99,8 @@ func (rw *rlpxFrameRW) ReadMsg() (msg Msg, err error) {
return msg, err
}
// verify header mac
- shouldMAC := updateHeaderMAC(rw.ingressMAC, rw.macCipher, headbuf[:16])
- if !hmac.Equal(shouldMAC[:16], headbuf[16:]) {
+ shouldMAC := updateMAC(rw.ingressMAC, rw.macCipher, headbuf[:16])
+ if !hmac.Equal(shouldMAC, headbuf[16:]) {
return msg, errors.New("bad header MAC")
}
rw.dec.XORKeyStream(headbuf[:16], headbuf[:16]) // first half is now decrypted
@@ -115,11 +119,12 @@ func (rw *rlpxFrameRW) ReadMsg() (msg Msg, err error) {
// read and validate frame MAC. we can re-use headbuf for that.
rw.ingressMAC.Write(framebuf)
- if _, err := io.ReadFull(rw.conn, headbuf); err != nil {
+ fmacseed := rw.ingressMAC.Sum(nil)
+ if _, err := io.ReadFull(rw.conn, headbuf[:16]); err != nil {
return msg, err
}
- shouldMAC = updateHeaderMAC(rw.ingressMAC, rw.macCipher, rw.ingressMAC.Sum(nil))
- if !hmac.Equal(shouldMAC, headbuf) {
+ shouldMAC = updateMAC(rw.ingressMAC, rw.macCipher, fmacseed)
+ if !hmac.Equal(shouldMAC, headbuf[:16]) {
return msg, errors.New("bad frame MAC")
}
@@ -136,14 +141,16 @@ func (rw *rlpxFrameRW) ReadMsg() (msg Msg, err error) {
return msg, nil
}
-func updateHeaderMAC(mac hash.Hash, block cipher.Block, header []byte) []byte {
+// 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] ^= header[i]
+ aesbuf[i] ^= seed[i]
}
mac.Write(aesbuf)
- return mac.Sum(nil)
+ return mac.Sum(nil)[:16]
}
func readInt24(b []byte) uint32 {