1 files changed, 180 insertions, 0 deletions
diff --git a/dhcpv6/dhcpv6message.go b/dhcpv6/dhcpv6message.go
new file mode 100644
index 0000000..4461c50
--- /dev/null
+++ b/dhcpv6/dhcpv6message.go
@@ -0,0 +1,180 @@
+package dhcpv6
+
+import (
+	"crypto/rand"
+	"encoding/binary"
+	"fmt"
+	"github.com/insomniacslk/dhcp/dhcpv6/options"
+	"github.com/insomniacslk/dhcp/iana"
+	"log"
+	"net"
+	"time"
+)
+
+const MessageHeaderSize = 4
+
+type DHCPv6Message struct {
+	messageType   MessageType
+	transactionID uint32 // only 24 bits are used though
+	options       []options.Option
+}
+
+func BytesToTransactionID(data []byte) (*uint32, error) {
+	// return a uint32 from a  sequence of bytes, representing a transaction ID.
+	// Transaction IDs are three-bytes long. If the provided data is shorter than
+	// 3 bytes, it return an error. If longer, will use the first three bytes
+	// only.
+	if len(data) < 3 {
+		return nil, fmt.Errorf("Invalid transaction ID: less than 3 bytes")
+	}
+	buf := make([]byte, 4)
+	copy(buf[1:4], data[:3])
+	tid := binary.BigEndian.Uint32(buf)
+	return &tid, nil
+}
+
+func GenerateTransactionID() (*uint32, error) {
+	var tid *uint32
+	for {
+		tidBytes := make([]byte, 4)
+		n, err := rand.Read(tidBytes)
+		if n != 4 {
+			return nil, fmt.Errorf("Invalid random sequence: shorter than 4 bytes")
+		}
+		tid, err = BytesToTransactionID(tidBytes)
+		if err != nil {
+			return nil, err
+		}
+		if tid == nil {
+			return nil, fmt.Errorf("Error: got a nil Transaction ID")
+		}
+		// retry until != 0
+		// TODO add retry limit
+		if *tid != 0 {
+			break
+		}
+	}
+	return tid, nil
+}
+
+// Return a time integer suitable for DUID-LLT, i.e. the current time counted in
+// seconds since January 1st, 2000, midnight UTC, modulo 2^32
+func GetTime() uint32 {
+	now := time.Since(time.Date(2000, time.January, 1, 0, 0, 0, 0, time.UTC))
+	return uint32((now.Nanoseconds() / 1000000000) % 0xffffffff)
+}
+
+// Create a new SOLICIT message with DUID-LLT, using the given network
+// interface's hardware address and current time
+func NewSolicitForInterface(ifname string) (*DHCPv6Message, error) {
+	d, err := NewMessage()
+	if err != nil {
+		return nil, err
+	}
+	d.SetMessage(SOLICIT)
+	iface, err := net.InterfaceByName(ifname)
+	if err != nil {
+		return nil, err
+	}
+	cid := options.OptClientId{}
+	cid.SetClientID(options.Duid{
+		Type:          options.DUID_LLT,
+		HwType:        iana.HwTypeEthernet,
+		Time:          GetTime(),
+		LinkLayerAddr: iface.HardwareAddr,
+	})
+
+	d.AddOption(&cid)
+	oro := options.OptRequestedOption{}
+	oro.SetRequestedOptions([]options.OptionCode{
+		options.DNS_RECURSIVE_NAME_SERVER,
+		options.DOMAIN_SEARCH_LIST,
+	})
+	d.AddOption(&oro)
+	d.AddOption(&options.OptElapsedTime{})
+	// FIXME use real values for IA_NA
+	iaNa := options.OptIANA{}
+	iaNa.SetIAID([4]byte{0x27, 0xfe, 0x8f, 0x95})
+	iaNa.SetT1(0xe10)
+	iaNa.SetT2(0x1518)
+	d.AddOption(&iaNa)
+	return d, nil
+}
+
+func (d *DHCPv6Message) Type() MessageType {
+	return d.messageType
+}
+
+func (d *DHCPv6Message) SetMessage(messageType MessageType) {
+	if d.MessageTypeToString() == "" {
+		log.Printf("Warning: unknown DHCPv6 message type: %v", messageType)
+	}
+	d.messageType = messageType
+}
+
+func (d *DHCPv6Message) MessageTypeToString() string {
+	return MessageTypeToString(d.messageType)
+}
+
+func (d *DHCPv6Message) TransactionID() uint32 {
+	return d.transactionID
+}
+
+func (d *DHCPv6Message) SetTransactionID(tid uint32) {
+	ttid := tid & 0x00ffffff
+	if ttid != tid {
+		log.Printf("Warning: truncating transaction ID that is longer than 24 bits: %v", tid)
+	}
+	d.transactionID = ttid
+}
+
+func (d *DHCPv6Message) Options() []options.Option {
+	return d.options
+}
+
+func (d *DHCPv6Message) SetOptions(options []options.Option) {
+	d.options = options
+}
+
+func (d *DHCPv6Message) AddOption(option options.Option) {
+	d.options = append(d.options, option)
+}
+
+func (d *DHCPv6Message) String() string {
+	return fmt.Sprintf("DHCPv6Message(messageType=%v transactionID=0x%06x, %d options)",
+		d.MessageTypeToString(), d.TransactionID(), len(d.options),
+	)
+}
+
+func (d *DHCPv6Message) Summary() string {
+	ret := fmt.Sprintf(
+		"DHCPv6Message\n"+
+			"  messageType=%v\n"+
+			"  transactionid=0x%06x\n",
+		d.MessageTypeToString(),
+		d.TransactionID(),
+	)
+	ret += "  options=["
+	if len(d.options) > 0 {
+		ret += "\n"
+	}
+	for _, opt := range d.options {
+		ret += fmt.Sprintf("    %v\n", opt.String())
+	}
+	ret += "  ]\n"
+	return ret
+}
+
+// Convert a DHCPv6Message structure into its binary representation, suitable for being
+// sent over the network
+func (d *DHCPv6Message) ToBytes() []byte {
+	var ret []byte
+	ret = append(ret, byte(d.messageType))
+	tidBytes := make([]byte, 4)
+	binary.BigEndian.PutUint32(tidBytes, d.transactionID)
+	ret = append(ret, tidBytes[1:4]...) // discard the first byte
+	for _, opt := range d.options {
+		ret = append(ret, opt.ToBytes()...)
+	}
+	return ret
+}