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control/noise: make message headers match the specification.

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Only the initiation message should carry a protocol version, all
others are just type+len.

Signed-off-by: David Anderson <danderson@tailscale.com>
This commit is contained in:
David Anderson
2021-10-25 17:24:32 -07:00
committed by Dave Anderson
parent a63c4ab378
commit d3acd35a90
5 changed files with 65 additions and 91 deletions
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control/noise/conn.go
+7 -9
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@@ -28,7 +28,7 @@ const (
maxMessageSize = 4096
// maxCiphertextSize is the maximum amount of ciphertext bytes
// that one protocol frame can carry, after framing.
maxCiphertextSize = maxMessageSize - headerLen
maxCiphertextSize = maxMessageSize - 3
// maxPlaintextSize is the maximum amount of plaintext bytes that
// one protocol frame can carry, after encryption and framing.
maxPlaintextSize = maxCiphertextSize - chp.Overhead
@@ -115,11 +115,8 @@ func (c *Conn) readNLocked(total int) ([]byte, error) {
// decryptLocked decrypts msg (which is header+ciphertext) in-place
// and sets c.rx.plaintext to the decrypted bytes.
func (c *Conn) decryptLocked(msg []byte) (err error) {
if hdrVersion(msg) != c.version {
return fmt.Errorf("received message with unexpected protocol version %d, want %d", hdrVersion(msg), c.version)
}
if hdrType(msg) != msgTypeRecord {
return fmt.Errorf("received message with unexpected type %d, want %d", hdrType(msg), msgTypeRecord)
if msgType := msg[0]; msgType != msgTypeRecord {
return fmt.Errorf("received message with unexpected type %d, want %d", msgType, msgTypeRecord)
}
// We don't check the length field here, because the caller
// already did in order to figure out how big the msg slice should
@@ -156,7 +153,8 @@ func (c *Conn) encryptLocked(plaintext []byte) ([]byte, error) {
return nil, errCipherExhausted{}
}
setHeader(c.tx.buf[:headerLen], protocolVersion, msgTypeRecord, len(plaintext)+chp.Overhead)
c.tx.buf[0] = msgTypeRecord
binary.BigEndian.PutUint16(c.tx.buf[1:headerLen], uint16(len(plaintext)+chp.Overhead))
ret := c.tx.cipher.Seal(c.tx.buf[:headerLen], c.tx.nonce[:], plaintext, nil)
// Safe to increment the nonce here, because we checked for nonce
@@ -177,7 +175,7 @@ func (c *Conn) wholeMessageLocked() []byte {
return nil
}
bs := c.rx.buf[c.rx.next:c.rx.n]
totalSize := headerLen + hdrLen(bs)
totalSize := headerLen + int(binary.BigEndian.Uint16(bs[1:3]))
if len(bs) < totalSize {
return nil
}
@@ -211,7 +209,7 @@ func (c *Conn) decryptOneLocked() error {
}
// The rest of the header (besides the length field) gets verified
// in decryptLocked, not here.
messageLen := headerLen + hdrLen(bs)
messageLen := headerLen + int(binary.BigEndian.Uint16(bs[1:3]))
bs, err = c.readNLocked(messageLen)
if err != nil {
return err