dhcpv4: introduce TransactionID type.

7 files changed, 30 insertions, 30 deletions

diff --git a/dhcpv4/async/client.go b/dhcpv4/async/client.go
index e6c7302..c37d249 100644
--- a/dhcpv4/async/client.go
+++ b/dhcpv4/async/client.go
@@ -34,7 +34,7 @@ type Client struct {
 	receiveQueue chan *dhcpv4.DHCPv4
 	sendQueue    chan *dhcpv4.DHCPv4
 	packetsLock  sync.Mutex
-	packets      map[uint32]*promise.Promise
+	packets      map[dhcpv4.TransactionID]*promise.Promise
 	errors       chan error
 }
 
@@ -69,7 +69,7 @@ func (c *Client) Open(bufferSize int) error {
 	c.stopping = new(sync.WaitGroup)
 	c.sendQueue = make(chan *dhcpv4.DHCPv4, bufferSize)
 	c.receiveQueue = make(chan *dhcpv4.DHCPv4, bufferSize)
-	c.packets = make(map[uint32]*promise.Promise)
+	c.packets = make(map[dhcpv4.TransactionID]*promise.Promise)
 	c.packetsLock = sync.Mutex{}
 	c.errors = make(chan error)
 
diff --git a/dhcpv4/dhcpv4.go b/dhcpv4/dhcpv4.go
index 2931565..4660dba 100644
--- a/dhcpv4/dhcpv4.go
+++ b/dhcpv4/dhcpv4.go
@@ -25,7 +25,7 @@ type DHCPv4 struct {
 	hwType         iana.HwTypeType
 	hwAddrLen      uint8
 	hopCount       uint8
-	transactionID  uint32
+	transactionID  TransactionID
 	numSeconds     uint16
 	flags          uint16
 	clientIPAddr   net.IP
@@ -83,17 +83,13 @@ func GetExternalIPv4Addrs(addrs []net.Addr) ([]net.IP, error) {
 
 // GenerateTransactionID generates a random 32-bits number suitable for use as
 // TransactionID
-func GenerateTransactionID() (*uint32, error) {
-	b := make([]byte, 4)
-	n, err := rand.Read(b)
+func GenerateTransactionID() (TransactionID, error) {
+	var xid TransactionID
+	n, err := rand.Read(xid[:])
 	if n != 4 {
-		return nil, errors.New("Invalid random sequence: smaller than 32 bits")
+		return xid, errors.New("invalid random sequence for transaction ID: smaller than 32 bits")
 	}
-	if err != nil {
-		return nil, err
-	}
-	tid := binary.LittleEndian.Uint32(b)
-	return &tid, nil
+	return xid, err
 }
 
 // New creates a new DHCPv4 structure and fill it up with default values. It
@@ -101,7 +97,7 @@ func GenerateTransactionID() (*uint32, error) {
 // See also NewDiscovery, NewOffer, NewRequest, NewAcknowledge, NewInform and
 // NewRelease .
 func New() (*DHCPv4, error) {
-	tid, err := GenerateTransactionID()
+	xid, err := GenerateTransactionID()
 	if err != nil {
 		return nil, err
 	}
@@ -110,7 +106,7 @@ func New() (*DHCPv4, error) {
 		hwType:        iana.HwTypeEthernet,
 		hwAddrLen:     6,
 		hopCount:      0,
-		transactionID: *tid,
+		transactionID: xid,
 		numSeconds:    0,
 		flags:         0,
 		clientIPAddr:  net.IPv4zero,
@@ -281,7 +277,6 @@ func FromBytes(data []byte) (*DHCPv4, error) {
 		hwType:        iana.HwTypeType(data[1]),
 		hwAddrLen:     data[2],
 		hopCount:      data[3],
-		transactionID: binary.BigEndian.Uint32(data[4:8]),
 		numSeconds:    binary.BigEndian.Uint16(data[8:10]),
 		flags:         binary.BigEndian.Uint16(data[10:12]),
 		clientIPAddr:  net.IP(data[12:16]),
@@ -289,6 +284,7 @@ func FromBytes(data []byte) (*DHCPv4, error) {
 		serverIPAddr:  net.IP(data[20:24]),
 		gatewayIPAddr: net.IP(data[24:28]),
 	}
+	copy(d.transactionID[:], data[4:8])
 	copy(d.clientHwAddr[:], data[28:44])
 	copy(d.serverHostName[:], data[44:108])
 	copy(d.bootFileName[:], data[108:236])
@@ -365,13 +361,13 @@ func (d *DHCPv4) SetHopCount(hopCount uint8) {
 }
 
 // TransactionID returns the transaction ID as 32 bit unsigned integer.
-func (d *DHCPv4) TransactionID() uint32 {
+func (d *DHCPv4) TransactionID() TransactionID {
 	return d.transactionID
 }
 
 // SetTransactionID sets the value for the transaction ID.
-func (d *DHCPv4) SetTransactionID(transactionID uint32) {
-	d.transactionID = transactionID
+func (d *DHCPv4) SetTransactionID(xid TransactionID) {
+	d.transactionID = xid
 }
 
 // NumSeconds returns the number of seconds.
@@ -731,15 +727,13 @@ func (d *DHCPv4) IsOptionRequested(requested OptionCode) bool {
 func (d *DHCPv4) ToBytes() []byte {
 	// This won't check if the End option is present, you've been warned
 	var ret []byte
-	u32 := make([]byte, 4)
 	u16 := make([]byte, 2)
 
 	ret = append(ret, byte(d.opcode))
 	ret = append(ret, byte(d.hwType))
 	ret = append(ret, byte(d.hwAddrLen))
 	ret = append(ret, byte(d.hopCount))
-	binary.BigEndian.PutUint32(u32, d.transactionID)
-	ret = append(ret, u32...)
+	ret = append(ret, d.transactionID[:]...)
 	binary.BigEndian.PutUint16(u16, d.numSeconds)
 	ret = append(ret, u16...)
 	binary.BigEndian.PutUint16(u16, d.flags)
diff --git a/dhcpv4/dhcpv4_test.go b/dhcpv4/dhcpv4_test.go
index 283e728..2e5b8b0 100644
--- a/dhcpv4/dhcpv4_test.go
+++ b/dhcpv4/dhcpv4_test.go
@@ -65,7 +65,7 @@ func TestFromBytes(t *testing.T) {
 	require.Equal(t, d.HwType(), iana.HwTypeEthernet)
 	require.Equal(t, d.HwAddrLen(), byte(6))
 	require.Equal(t, d.HopCount(), byte(3))
-	require.Equal(t, d.TransactionID(), uint32(0xaabbccdd))
+	require.Equal(t, d.TransactionID(), TransactionID{0xaa, 0xbb, 0xcc, 0xdd})
 	require.Equal(t, d.NumSeconds(), uint16(3))
 	require.Equal(t, d.Flags(), uint16(1))
 	require.True(t, d.ClientIPAddr().Equal(net.IPv4zero))
@@ -177,9 +177,9 @@ func TestSettersAndGetters(t *testing.T) {
 	require.Equal(t, uint8(1), d.HopCount())
 
 	// getter/setter for TransactionID
-	require.Equal(t, uint32(0xaabbccdd), d.TransactionID())
-	d.SetTransactionID(0xeeff0011)
-	require.Equal(t, uint32(0xeeff0011), d.TransactionID())
+	require.Equal(t, TransactionID{0xaa, 0xbb, 0xcc, 0xdd}, d.TransactionID())
+	d.SetTransactionID(TransactionID{0xee, 0xff, 0x00, 0x11})
+	require.Equal(t, TransactionID{0xee, 0xff, 0x00, 0x11}, d.TransactionID())
 
 	// getter/setter for TransactionID
 	require.Equal(t, uint16(3), d.NumSeconds())
@@ -318,7 +318,7 @@ func TestNewToBytes(t *testing.T) {
 	require.NoError(t, err)
 	// fix TransactionID to match the expected one, since it's randomly
 	// generated in New()
-	d.SetTransactionID(0x11223344)
+	d.SetTransactionID(TransactionID{0x11, 0x22, 0x33, 0x44})
 	got := d.ToBytes()
 	require.Equal(t, expected, got)
 }
diff --git a/dhcpv4/modifiers.go b/dhcpv4/modifiers.go
index 033718e..ba58884 100644
--- a/dhcpv4/modifiers.go
+++ b/dhcpv4/modifiers.go
@@ -7,7 +7,7 @@ import (
 )
 
 // WithTransactionID sets the Transaction ID for the DHCPv4 packet
-func WithTransactionID(xid uint32) Modifier {
+func WithTransactionID(xid TransactionID) Modifier {
 	return func(d *DHCPv4) *DHCPv4 {
 		d.SetTransactionID(xid)
 		return d
diff --git a/dhcpv4/modifiers_test.go b/dhcpv4/modifiers_test.go
index f50e40b..d85d2e9 100644
--- a/dhcpv4/modifiers_test.go
+++ b/dhcpv4/modifiers_test.go
@@ -10,8 +10,8 @@ import (
 func TestTransactionIDModifier(t *testing.T) {
 	d, err := New()
 	require.NoError(t, err)
-	d = WithTransactionID(0xddccbbaa)(d)
-	require.Equal(t, uint32(0xddccbbaa), d.TransactionID())
+	d = WithTransactionID(TransactionID{0xdd, 0xcc, 0xbb, 0xaa})(d)
+	require.Equal(t, TransactionID{0xdd, 0xcc, 0xbb, 0xaa}, d.TransactionID())
 }
 
 func TestBroadcastModifier(t *testing.T) {
diff --git a/dhcpv4/server_test.go b/dhcpv4/server_test.go
index 68bd694..454a113 100644
--- a/dhcpv4/server_test.go
+++ b/dhcpv4/server_test.go
@@ -113,7 +113,7 @@ func TestServerActivateAndServe(t *testing.T) {
 	require.NoError(t, err)
 	require.NotEqual(t, 0, len(ifaces))
 
-	xid := uint32(0xaabbccdd)
+	xid := TransactionID{0xaa, 0xbb, 0xcc, 0xdd}
 	hwaddr := [16]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf}
 
 	modifiers := []Modifier{
diff --git a/dhcpv4/types.go b/dhcpv4/types.go
index 5919275..aea5caf 100644
--- a/dhcpv4/types.go
+++ b/dhcpv4/types.go
@@ -3,6 +3,12 @@ package dhcpv4
 // values from http://www.networksorcery.com/enp/protocol/dhcp.htm and
 // http://www.networksorcery.com/enp/protocol/bootp/options.htm
 
+// TransactionID represents a 4-byte DHCP transaction ID as defined in RFC 951,
+// Section 3.
+//
+// The TransactionID is used to match DHCP replies to their original request.
+type TransactionID [4]byte
+
 // MessageType represents the possible DHCP message types - DISCOVER, OFFER, etc
 type MessageType byte