mixpool: remove expiry from message interface

mixing/mixpool/mixpool.go

@@ -601,14 +601,6 @@ func (p *Pool) AcceptMessage(msg mixing.Message) (accepted mixing.Message, err e
 	}
 	id := (*idPubKey)(msg.Pub())
 
-	// Check that expiry has not been reached, nor that it is too far
-	// into the future.  This limits replay attacks.
-	_, curHeight := p.blockchain.BestHeader()
-	err = checkExpiry(msg, uint32(curHeight), p.params)
-	if err != nil {
-		return nil, err
-	}
-
 	var msgtype msgtype
 	switch msg := msg.(type) {
 	case *wire.MsgMixPairReq:
@@ -703,19 +695,18 @@ func (p *Pool) AcceptMessage(msg mixing.Message) (accepted mixing.Message, err e
 	return msg, nil
 }
 
-func checkExpiry(msg mixing.Message, curHeight uint32, params *chaincfg.Params) error {
-	expires := msg.Expires()
-	maxExpiry := mixing.MaxExpiry(curHeight, params)
+func (p *Pool) acceptPR(pr *wire.MsgMixPairReq, hash *chainhash.Hash, id *idPubKey) (accepted *wire.MsgMixPairReq, err error) {
+	// Check that expiry has not been reached, nor that it is too far
+	// into the future.  This limits replay attacks.
+	_, curHeight := p.blockchain.BestHeader()
+	maxExpiry := mixing.MaxExpiry(uint32(curHeight), p.params)
 	switch {
-	case curHeight >= expires:
-		return fmt.Errorf("message has expired")
-	case expires > maxExpiry:
-		return fmt.Errorf("expiry is too far into future")
+	case uint32(curHeight) >= pr.Expiry:
+		return nil, fmt.Errorf("message has expired")
+	case pr.Expiry > maxExpiry:
+		return nil, fmt.Errorf("expiry is too far into future")
 	}
-	return nil
-}
 
-func (p *Pool) acceptPR(pr *wire.MsgMixPairReq, hash *chainhash.Hash, id *idPubKey) (accepted *wire.MsgMixPairReq, err error) {
 	if len(pr.UTXOs) == 0 {
 		return nil, fmt.Errorf("at least one UTXO must be submitted")
 	}