addr: Parse address lifetime information from IFA_CACHEINFO attr

This adds parsing of the preferred and valid lifetime information from the
netlink IFA_CACHEINFO attribute. They are stored as PreferedLft and ValidLft in
the Addr struct if found.

Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>

addr.go

@@ -10,11 +10,13 @@ import (
 // include a mask, so it stores the address as a net.IPNet.
 type Addr struct {
 	*net.IPNet
-	Label     string
-	Flags     int
-	Scope     int
-	Peer      *net.IPNet
-	Broadcast net.IP
+	Label       string
+	Flags       int
+	Scope       int
+	Peer        *net.IPNet
+	Broadcast   net.IP
+	PreferedLft int
+	ValidLft    int
 }
 
 // String returns $ip/$netmask $label

addr_linux.go

@@ -199,6 +199,10 @@ func parseAddr(m []byte) (addr Addr, family, index int, err error) {
 			addr.Label = string(attr.Value[:len(attr.Value)-1])
 		case IFA_FLAGS:
 			addr.Flags = int(native.Uint32(attr.Value[0:4]))
+		case nl.IFA_CACHEINFO:
+			ci := nl.DeserializeIfaCacheInfo(attr.Value)
+			addr.PreferedLft = int(ci.IfaPrefered)
+			addr.ValidLft = int(ci.IfaValid)
 		}
 	}
 

nl/addr_linux.go

@@ -45,3 +45,32 @@ func (msg *IfAddrmsg) Serialize() []byte {
 func (msg *IfAddrmsg) Len() int {
 	return syscall.SizeofIfAddrmsg
 }
+
+// struct ifa_cacheinfo {
+// 	__u32	ifa_prefered;
+// 	__u32	ifa_valid;
+// 	__u32	cstamp; /* created timestamp, hundredths of seconds */
+// 	__u32	tstamp; /* updated timestamp, hundredths of seconds */
+// };
+
+const IFA_CACHEINFO = 6
+const SizeofIfaCacheInfo = 0x10
+
+type IfaCacheInfo struct {
+	IfaPrefered uint32
+	IfaValid    uint32
+	Cstamp      uint32
+	Tstamp      uint32
+}
+
+func (msg *IfaCacheInfo) Len() int {
+	return SizeofIfaCacheInfo
+}
+
+func DeserializeIfaCacheInfo(b []byte) *IfaCacheInfo {
+	return (*IfaCacheInfo)(unsafe.Pointer(&b[0:SizeofIfaCacheInfo][0]))
+}
+
+func (msg *IfaCacheInfo) Serialize() []byte {
+	return (*(*[SizeofIfaCacheInfo]byte)(unsafe.Pointer(msg)))[:]
+}

nl/addr_linux_test.go

@@ -37,3 +37,32 @@ func TestIfAddrmsgDeserializeSerialize(t *testing.T) {
 	msg := DeserializeIfAddrmsg(orig)
 	testDeserializeSerialize(t, orig, safemsg, msg)
 }
+
+func (msg *IfaCacheInfo) write(b []byte) {
+	native := NativeEndian()
+	native.PutUint32(b[0:4], uint32(msg.IfaPrefered))
+	native.PutUint32(b[4:8], uint32(msg.IfaValid))
+	native.PutUint32(b[8:12], uint32(msg.Cstamp))
+	native.PutUint32(b[12:16], uint32(msg.Tstamp))
+}
+
+func (msg *IfaCacheInfo) serializeSafe() []byte {
+	length := SizeofIfaCacheInfo
+	b := make([]byte, length)
+	msg.write(b)
+	return b
+}
+
+func deserializeIfaCacheInfoSafe(b []byte) *IfaCacheInfo {
+	var msg = IfaCacheInfo{}
+	binary.Read(bytes.NewReader(b[0:SizeofIfaCacheInfo]), NativeEndian(), &msg)
+	return &msg
+}
+
+func TestIfaCacheInfoDeserializeSerialize(t *testing.T) {
+	var orig = make([]byte, SizeofIfaCacheInfo)
+	rand.Read(orig)
+	safemsg := deserializeIfaCacheInfoSafe(orig)
+	msg := DeserializeIfaCacheInfo(orig)
+	testDeserializeSerialize(t, orig, safemsg, msg)
+}