[dhcpv6] Solicit messages derive default IAID from MAC address

IAID must be set by the client. This patch generates the IAID from the
MAC address of the interface. To do so, a new WithIAID modifier is
added, the interface of NewSolicitWithCID now requires a hwaddr
parameter, and NewAdvertiseFromSolicit copies the IA_NA option from the
solicit if present.

Signed-off-by: Andrea Barberio <insomniac@slackware.it>

5 files changed, 42 insertions, 10 deletions

diff --git a/dhcpv6/async/client_test.go b/dhcpv6/async/client_test.go
index 9b58112..a3b076c 100644
--- a/dhcpv6/async/client_test.go
+++ b/dhcpv6/async/client_test.go
@@ -26,7 +26,7 @@ func solicit(input string) (*dhcpv6.Message, error) {
 		Time:          dhcpv6.GetTime(),
 		LinkLayerAddr: mac,
 	}
-	return dhcpv6.NewSolicitWithCID(duid)
+	return dhcpv6.NewSolicitWithCID(duid, mac, dhcpv6.WithIAID([4]byte{1, 2, 3, 4}))
 }
 
 // server creates a server which responds with a predefined response
diff --git a/dhcpv6/dhcpv6_test.go b/dhcpv6/dhcpv6_test.go
index d509572..ac44314 100644
--- a/dhcpv6/dhcpv6_test.go
+++ b/dhcpv6/dhcpv6_test.go
@@ -144,6 +144,7 @@ func TestNewAdvertiseFromSolicit(t *testing.T) {
 	cid := OptClientId{}
 	s.AddOption(&cid)
 	duid := Duid{}
+	WithIAID([4]byte{1, 2, 3, 4})(&s)
 
 	a, err := NewAdvertiseFromSolicit(&s, WithServerID(duid))
 	require.NoError(t, err)
@@ -207,7 +208,7 @@ func TestNewMessageTypeSolicitWithCID(t *testing.T) {
 		LinkLayerAddr: hwAddr,
 	}
 
-	s, err := NewSolicitWithCID(duid)
+	s, err := NewSolicitWithCID(duid, hwAddr)
 	require.NoError(t, err)
 
 	require.Equal(t, s.Type(), MessageTypeSolicit)
@@ -227,6 +228,14 @@ func TestNewMessageTypeSolicitWithCID(t *testing.T) {
 	require.Contains(t, opts, OptionDNSRecursiveNameServer)
 	require.Contains(t, opts, OptionDomainSearchList)
 	require.Equal(t, len(opts), 2)
+
+	// Check IA_NA
+	iaid := [4]byte{hwAddr[2], hwAddr[3], hwAddr[4], hwAddr[5]}
+	iaNaOption := s.GetOneOption(OptionIANA)
+	require.NotNil(t, iaNaOption)
+	iaNa, ok := iaNaOption.(*OptIANA)
+	require.True(t, ok)
+	require.Equal(t, iaid, iaNa.IaId)
 }
 
 func TestIsUsingUEFIArchTypeTrue(t *testing.T) {
diff --git a/dhcpv6/dhcpv6message.go b/dhcpv6/dhcpv6message.go
index 9237c1b..bc23156 100644
--- a/dhcpv6/dhcpv6message.go
+++ b/dhcpv6/dhcpv6message.go
@@ -43,7 +43,7 @@ func GetTime() uint32 {
 }
 
 // NewSolicitWithCID creates a new SOLICIT message with CID.
-func NewSolicitWithCID(duid Duid, modifiers ...Modifier) (*Message, error) {
+func NewSolicitWithCID(duid Duid, hwaddr net.HardwareAddr, modifiers ...Modifier) (*Message, error) {
 	m, err := NewMessage()
 	if err != nil {
 		return nil, err
@@ -57,12 +57,13 @@ func NewSolicitWithCID(duid Duid, modifiers ...Modifier) (*Message, error) {
 	})
 	m.AddOption(oro)
 	m.AddOption(&OptElapsedTime{})
-	// FIXME use real values for IA_NA
-	iaNa := &OptIANA{}
-	iaNa.IaId = [4]byte{0xfa, 0xce, 0xb0, 0x0c}
-	iaNa.T1 = 0xe10
-	iaNa.T2 = 0x1518
-	m.AddOption(iaNa)
+	if len(hwaddr) < 4 {
+		return nil, errors.New("short hardware addrss: less than 4 bytes")
+	}
+	l := len(hwaddr)
+	var iaid [4]byte
+	copy(iaid[:], hwaddr[l-4:l])
+	modifiers = append([]Modifier{WithIAID(iaid)}, modifiers...)
 	// Apply modifiers
 	for _, mod := range modifiers {
 		mod(m)
@@ -79,7 +80,7 @@ func NewSolicit(ifaceHWAddr net.HardwareAddr, modifiers ...Modifier) (*Message,
 		Time:          GetTime(),
 		LinkLayerAddr: ifaceHWAddr,
 	}
-	return NewSolicitWithCID(duid, modifiers...)
+	return NewSolicitWithCID(duid, ifaceHWAddr, modifiers...)
 }
 
 // NewAdvertiseFromSolicit creates a new ADVERTISE packet based on an SOLICIT packet.
@@ -101,6 +102,12 @@ func NewAdvertiseFromSolicit(sol *Message, modifiers ...Modifier) (*Message, err
 		return nil, errors.New("Client ID cannot be nil in SOLICIT when building ADVERTISE")
 	}
 	adv.AddOption(cid)
+	// add IA_NA
+	iaNa := sol.GetOneOption(OptionIANA)
+	if iaNa == nil {
+		return nil, fmt.Errorf("IA_NA cannot be nil in SOLICIT when building ADVERTISE")
+	}
+	adv.AddOption(iaNa)
 
 	// apply modifiers
 	for _, mod := range modifiers {
diff --git a/dhcpv6/dhcpv6relay_test.go b/dhcpv6/dhcpv6relay_test.go
index 270dd52..6c7f96f 100644
--- a/dhcpv6/dhcpv6relay_test.go
+++ b/dhcpv6/dhcpv6relay_test.go
@@ -90,6 +90,7 @@ func TestNewRelayRepFromRelayForw(t *testing.T) {
 	s, err := NewMessage()
 	require.NoError(t, err)
 	s.AddOption(&OptClientId{})
+	WithIAID([4]byte{1, 2, 3, 4})(s)
 	orm := OptRelayMsg{}
 	orm.SetRelayMessage(s)
 	rf.AddOption(&orm)
diff --git a/dhcpv6/modifiers.go b/dhcpv6/modifiers.go
index eaa370d..200a602 100644
--- a/dhcpv6/modifiers.go
+++ b/dhcpv6/modifiers.go
@@ -77,6 +77,21 @@ func WithIANA(addrs ...OptIAAddress) Modifier {
 	}
 }
 
+// WithIAID updates an OptIANA option with the provided IAID
+func WithIAID(iaid [4]byte) Modifier {
+	return func(d DHCPv6) {
+		opt := d.GetOneOption(OptionIANA)
+		if opt == nil {
+			opt = &OptIANA{
+				Options: Options{},
+			}
+		}
+		iaNa := opt.(*OptIANA)
+		copy(iaNa.IaId[:], iaid[:])
+		d.UpdateOption(iaNa)
+	}
+}
+
 // WithDNS adds or updates an OptDNSRecursiveNameServer
 func WithDNS(dnses ...net.IP) Modifier {
 	return func(d DHCPv6) {