simplify truncated connection IDs in ConnectionParametersManager

handshake/connection_parameters_manager.go

@@ -2,7 +2,6 @@ package handshake
 
 import (
 	"bytes"
-	"encoding/binary"
 	"errors"
 	"sync"
 	"time"
@@ -16,11 +15,11 @@ import (
 // Warning: Writes may only be done from the crypto stream, see the comment
 // in GetSHLOMap().
 type ConnectionParametersManager struct {
-	params map[Tag][]byte
-	mutex  sync.RWMutex
+	mutex sync.RWMutex
 
 	flowControlNegotiated bool // have the flow control parameters for sending already been negotiated
 
+	truncateConnectionID               bool
 	maxStreamsPerConnection            uint32
 	idleConnectionStateLifetime        time.Duration
 	sendStreamFlowControlWindow        protocol.ByteCount
@@ -40,7 +39,6 @@ var (
 // NewConnectionParamatersManager creates a new connection parameters manager
 func NewConnectionParamatersManager() *ConnectionParametersManager {
 	return &ConnectionParametersManager{
-		params: make(map[Tag][]byte),
 		idleConnectionStateLifetime:        protocol.DefaultIdleTimeout,
 		sendStreamFlowControlWindow:        protocol.InitialStreamFlowControlWindow,     // can only be changed by the client
 		sendConnectionFlowControlWindow:    protocol.InitialConnectionFlowControlWindow, // can only be changed by the client
@@ -58,7 +56,11 @@ func (h *ConnectionParametersManager) SetFromMap(params map[Tag][]byte) error {
 	for key, value := range params {
 		switch key {
 		case TagTCID:
-			h.params[key] = value
+			clientValue, err := utils.ReadUint32(bytes.NewBuffer(value))
+			if err != nil {
+				return ErrMalformedTag
+			}
+			h.truncateConnectionID = (clientValue == 0)
 		case TagMSPC:
 			clientValue, err := utils.ReadUint32(bytes.NewBuffer(value))
 			if err != nil {
@@ -109,18 +111,6 @@ func (h *ConnectionParametersManager) negotiateIdleConnectionStateLifetime(clien
 	return utils.MinDuration(clientValue, protocol.MaxIdleTimeout)
 }
 
-// getRawValue gets the byte-slice for a tag
-func (h *ConnectionParametersManager) getRawValue(tag Tag) ([]byte, error) {
-	h.mutex.RLock()
-	rawValue, ok := h.params[tag]
-	h.mutex.RUnlock()
-
-	if !ok {
-		return nil, errTagNotInConnectionParameterMap
-	}
-	return rawValue, nil
-}
-
 // GetSHLOMap gets all values (except crypto values) needed for the SHLO
 func (h *ConnectionParametersManager) GetSHLOMap() map[Tag][]byte {
 	sfcw := bytes.NewBuffer([]byte{})
@@ -187,16 +177,7 @@ func (h *ConnectionParametersManager) GetIdleConnectionStateLifetime() time.Dura
 
 // TruncateConnectionID determines if the client requests truncated ConnectionIDs
 func (h *ConnectionParametersManager) TruncateConnectionID() bool {
-	rawValue, err := h.getRawValue(TagTCID)
-	if err != nil {
-		return false
-	}
-	if len(rawValue) != 4 {
-		return false
-	}
-	value := binary.LittleEndian.Uint32(rawValue)
-	if value == 0 {
-		return true
-	}
-	return false
+	h.mutex.RLock()
+	defer h.mutex.RUnlock()
+	return h.truncateConnectionID
 }

handshake/connection_parameters_manager_test.go

@@ -14,24 +14,6 @@ var _ = Describe("ConnectionsParameterManager", func() {
 		cpm = NewConnectionParamatersManager()
 	})
 
-	It("stores and retrieves a value", func() {
-		tcid := []byte{0x13, 0x37}
-		values := map[Tag][]byte{
-			TagTCID: tcid,
-		}
-
-		cpm.SetFromMap(values)
-
-		val, err := cpm.getRawValue(TagTCID)
-		Expect(err).ToNot(HaveOccurred())
-		Expect(val).To(Equal(tcid))
-	})
-
-	It("returns an error for a tag that is not set", func() {
-		_, err := cpm.getRawValue(TagKEXS)
-		Expect(err).To(MatchError(errTagNotInConnectionParameterMap))
-	})
-
 	Context("SHLO", func() {
 		It("returns all parameters necessary for the SHLO", func() {
 			entryMap := cpm.GetSHLOMap()