wire-mix: review items

wire/common.go

@@ -517,6 +517,14 @@ func writeElement(w io.Writer, element interface{}) error {
 		}
 		return nil
 
+	// Mix identity
+	case *[33]byte:
+		_, err := w.Write(e[:])
+		if err != nil {
+			return err
+		}
+		return nil
+
 	// Mix signature
 	case *[64]byte:
 		_, err := w.Write(e[:])

wire/common_test.go

@@ -907,3 +907,27 @@ func TestRandomUint64Errors(t *testing.T) {
 		t.Errorf("Nonce is not 0 [%v]", nonce)
 	}
 }
+
+// repeat returns the byte slice containing count elements of the byte b.
+func repeat(b byte, count int) []byte {
+	s := make([]byte, count)
+	for i := range s {
+		s[i] = b
+	}
+	return s
+}
+
+// rhash returns a chainhash.Hash with all bytes set to b.
+func rhash(b byte) chainhash.Hash {
+	var h chainhash.Hash
+	for i := range h {
+		h[i] = b
+	}
+	return h
+}
+
+// varBytesLen returns the size required to encode l bytes as a varint
+// followed by the bytes themselves.
+func varBytesLen(l uint32) uint32 {
+	return uint32(VarIntSerializeSize(uint64(l))) + l
+}

wire/message_test.go

@@ -1,5 +1,5 @@
 // Copyright (c) 2013-2016 The btcsuite developers
-// Copyright (c) 2015-2023 The Decred developers
+// Copyright (c) 2015-2024 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -89,7 +89,7 @@ func TestMessage(t *testing.T) {
 	msgMixSR := NewMsgMixSlotReserve([33]byte{}, [32]byte{}, 1, 1, [][][]byte{{{}}}, []chainhash.Hash{})
 	msgMixDC := NewMsgMixDCNet([33]byte{}, [32]byte{}, 1, 1, []MixVect{make(MixVect, 1)}, []chainhash.Hash{})
 	msgMixCM := NewMsgMixConfirm([33]byte{}, [32]byte{}, 1, 1, NewMsgTx(), []chainhash.Hash{})
-	msgMixRS := NewMsgMixSecrets([33]byte{}, [32]byte{}, 1, 1, [32]byte{}, [][]byte{}, [][]byte{})
+	msgMixRS := NewMsgMixSecrets([33]byte{}, [32]byte{}, 1, 1, [32]byte{}, [][]byte{}, MixVect{})
 
 	tests := []struct {
 		in     Message     // Value to encode
@@ -128,7 +128,7 @@ func TestMessage(t *testing.T) {
 		{msgMixSR, msgMixSR, pver, MainNet, 165},
 		{msgMixDC, msgMixDC, pver, MainNet, 185},
 		{msgMixCM, msgMixCM, pver, MainNet, 177},
-		{msgMixRS, msgMixRS, pver, MainNet, 209},
+		{msgMixRS, msgMixRS, pver, MainNet, 196},
 	}
 
 	t.Logf("Running %d tests", len(tests))

wire/msgmixciphertexts.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2023 The Decred developers
+// Copyright (c) 2023-2024 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -46,14 +46,14 @@ func (msg *MsgMixCiphertexts) BtcDecode(r io.Reader, pver uint32) error {
 		return err
 	}
 
-	// Count is of both Ciphertexts and seen KeyExchanges.
+	// Count is of both Ciphertexts and seen SeenKeyExchanges.
 	count, err := ReadVarInt(r, pver)
 	if err != nil {
 		return err
 	}
-	if count > MaxPrevMixMsgs {
+	if count > MaxMixPeers {
 		msg := fmt.Sprintf("too many previous referenced messages [count %v, max %v]",
-			count, MaxPrevMixMsgs)
+			count, MaxMixPeers)
 		return messageError(op, ErrTooManyPrevMixMsgs, msg)
 	}
 
@@ -117,14 +117,14 @@ func (msg *MsgMixCiphertexts) Hash() chainhash.Hash {
 // panic.  This method is designed to work only with hashers returned by
 // blake256.New.
 func (msg *MsgMixCiphertexts) WriteHash(h hash.Hash) {
-	h.Reset()
-	writeElement(h, &msg.Signature)
-	msg.writeMessageNoSignature("", h, MixVersion)
-	sum := h.Sum(msg.hash[:0])
-	if len(sum) != len(msg.hash) {
+	if h.Size() != chainhash.HashSize {
 		s := fmt.Sprintf("hasher type %T has invalid Size() for chainhash.Hash", h)
 		panic(s)
 	}
+	h.Reset()
+	writeElement(h, &msg.Signature)
+	msg.writeMessageNoSignature("", h, MixVersion)
+	h.Sum(msg.hash[:0])
 }
 
 // writeMessageNoSignature serializes all elements of the message except for
@@ -136,23 +136,25 @@ func (msg *MsgMixCiphertexts) WriteHash(h hash.Hash) {
 func (msg *MsgMixCiphertexts) writeMessageNoSignature(op string, w io.Writer, pver uint32) error {
 	_, hashing := w.(hash.Hash)
 
-	err := writeElements(w, &msg.Identity, &msg.SessionID, msg.Expiry,
-		msg.Run)
-	if err != nil {
-		return err
-	}
-
 	count := len(msg.Ciphertexts)
 	if !hashing && count != len(msg.SeenKeyExchanges) {
-		msg := "differing counts of ciphertexts and seen key exchange messages"
+		msg := fmt.Sprintf("differing counts of ciphertexts (%d) "+
+			"and seen key exchange messages (%d)", count,
+			len(msg.SeenKeyExchanges))
 		return messageError(op, ErrInvalidMsg, msg)
 	}
-	if !hashing && count > MaxPrevMixMsgs {
+	if !hashing && count > MaxMixPeers {
 		msg := fmt.Sprintf("too many previous referenced messages [count %v, max %v]",
-			count, MaxPrevMixMsgs)
+			count, MaxMixPeers)
 		return messageError(op, ErrTooManyPrevMixMsgs, msg)
 	}
 
+	err := writeElements(w, &msg.Identity, &msg.SessionID, msg.Expiry,
+		msg.Run)
+	if err != nil {
+		return err
+	}
+
 	err = WriteVarInt(w, pver, uint64(count))
 	if err != nil {
 		return err
@@ -173,10 +175,10 @@ func (msg *MsgMixCiphertexts) writeMessageNoSignature(op string, w io.Writer, pv
 	return nil
 }
 
-// WriteSigned writes a tag identifying the message data, followed by all
+// WriteSignedData writes a tag identifying the message data, followed by all
 // message fields excluding the signature.  This is the data committed to when
 // the message is signed.
-func (msg *MsgMixCiphertexts) WriteSigned(h hash.Hash) {
+func (msg *MsgMixCiphertexts) WriteSignedData(h hash.Hash) {
 	WriteVarString(h, MixVersion, CmdMixCiphertexts+"-sig")
 	msg.writeMessageNoSignature("", h, MixVersion)
 }
@@ -190,6 +192,11 @@ func (msg *MsgMixCiphertexts) Command() string {
 // MaxPayloadLength returns the maximum length the payload can be for the
 // receiver.  This is part of the Message interface implementation.
 func (msg *MsgMixCiphertexts) MaxPayloadLength(pver uint32) uint32 {
+	if pver < MixVersion {
+		return 0
+	}
+
+	// See tests for this calculation.
 	return 552588
 }