2 files changed, 232 insertions, 0 deletions
diff --git a/dhcpv6/client6/client.go b/dhcpv6/client6/client.go
new file mode 100644
index 0000000..4075bde
--- /dev/null
+++ b/dhcpv6/client6/client.go
@@ -0,0 +1,218 @@
+package client6
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"time"
+
+	"github.com/insomniacslk/dhcp/dhcpv6"
+)
+
+// Client constants
+const (
+	DefaultWriteTimeout       = 3 * time.Second // time to wait for write calls
+	DefaultReadTimeout        = 3 * time.Second // time to wait for read calls
+	DefaultInterfaceUpTimeout = 3 * time.Second // time to wait before a network interface goes up
+	MaxUDPReceivedPacketSize  = 8192            // arbitrary size. Theoretically could be up to 65kb
+)
+
+// Broadcast destination IP addresses as defined by RFC 3315
+var (
+	AllDHCPRelayAgentsAndServers = net.ParseIP("ff02::1:2")
+	AllDHCPServers               = net.ParseIP("ff05::1:3")
+)
+
+// Client implements a DHCPv6 client
+type Client struct {
+	ReadTimeout  time.Duration
+	WriteTimeout time.Duration
+	LocalAddr    net.Addr
+	RemoteAddr   net.Addr
+}
+
+// NewClient returns a Client with default settings
+func NewClient() *Client {
+	return &Client{
+		ReadTimeout:  DefaultReadTimeout,
+		WriteTimeout: DefaultWriteTimeout,
+	}
+}
+
+// Exchange executes a 4-way DHCPv6 request (Solicit, Advertise, Request,
+// Reply). The modifiers will be applied to the Solicit and Request packets.
+// A common use is to make sure that the Solicit packet has the right options,
+// see modifiers.go
+func (c *Client) Exchange(ifname string, modifiers ...dhcpv6.Modifier) ([]dhcpv6.DHCPv6, error) {
+	conversation := make([]dhcpv6.DHCPv6, 0)
+	var err error
+
+	// Solicit
+	solicit, advertise, err := c.Solicit(ifname, modifiers...)
+	if solicit != nil {
+		conversation = append(conversation, solicit)
+	}
+	if err != nil {
+		return conversation, err
+	}
+	conversation = append(conversation, advertise)
+
+	// Decapsulate advertise if it's relayed before passing it to Request
+	if advertise.IsRelay() {
+		advertiseRelay := advertise.(*dhcpv6.DHCPv6Relay)
+		advertise, err = advertiseRelay.GetInnerMessage()
+		if err != nil {
+			return conversation, err
+		}
+	}
+	request, reply, err := c.Request(ifname, advertise, modifiers...)
+	if request != nil {
+		conversation = append(conversation, request)
+	}
+	if err != nil {
+		return conversation, err
+	}
+	conversation = append(conversation, reply)
+	return conversation, nil
+}
+
+func (c *Client) sendReceive(ifname string, packet dhcpv6.DHCPv6, expectedType dhcpv6.MessageType) (dhcpv6.DHCPv6, error) {
+	if packet == nil {
+		return nil, fmt.Errorf("Packet to send cannot be nil")
+	}
+	if expectedType == dhcpv6.MessageTypeNone {
+		// infer the expected type from the packet being sent
+		if packet.Type() == dhcpv6.MessageTypeSolicit {
+			expectedType = dhcpv6.MessageTypeAdvertise
+		} else if packet.Type() == dhcpv6.MessageTypeRequest {
+			expectedType = dhcpv6.MessageTypeReply
+		} else if packet.Type() == dhcpv6.MessageTypeRelayForward {
+			expectedType = dhcpv6.MessageTypeRelayReply
+		} else if packet.Type() == dhcpv6.MessageTypeLeaseQuery {
+			expectedType = dhcpv6.MessageTypeLeaseQueryReply
+		} // and probably more
+	}
+	// if no LocalAddr is specified, get the interface's link-local address
+	var laddr net.UDPAddr
+	if c.LocalAddr == nil {
+		llAddr, err := dhcpv6.GetLinkLocalAddr(ifname)
+		if err != nil {
+			return nil, err
+		}
+		laddr = net.UDPAddr{IP: llAddr, Port: dhcpv6.DefaultClientPort, Zone: ifname}
+	} else {
+		if addr, ok := c.LocalAddr.(*net.UDPAddr); ok {
+			laddr = *addr
+		} else {
+			return nil, fmt.Errorf("Invalid local address: not a net.UDPAddr: %v", c.LocalAddr)
+		}
+	}
+
+	// if no RemoteAddr is specified, use AllDHCPRelayAgentsAndServers
+	var raddr net.UDPAddr
+	if c.RemoteAddr == nil {
+		raddr = net.UDPAddr{IP: AllDHCPRelayAgentsAndServers, Port: dhcpv6.DefaultServerPort}
+	} else {
+		if addr, ok := c.RemoteAddr.(*net.UDPAddr); ok {
+			raddr = *addr
+		} else {
+			return nil, fmt.Errorf("Invalid remote address: not a net.UDPAddr: %v", c.RemoteAddr)
+		}
+	}
+
+	// prepare the socket to listen on for replies
+	conn, err := net.ListenUDP("udp6", &laddr)
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+	// wait for the listener to be ready, fail if it takes too much time
+	deadline := time.Now().Add(time.Second)
+	for {
+		if now := time.Now(); now.After(deadline) {
+			return nil, errors.New("Timed out waiting for listener to be ready")
+		}
+		if conn.LocalAddr() != nil {
+			break
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+
+	// send the packet out
+	conn.SetWriteDeadline(time.Now().Add(c.WriteTimeout))
+	_, err = conn.WriteTo(packet.ToBytes(), &raddr)
+	if err != nil {
+		return nil, err
+	}
+
+	// wait for a reply
+	oobdata := []byte{} // ignoring oob data
+	conn.SetReadDeadline(time.Now().Add(c.ReadTimeout))
+	var (
+		adv       dhcpv6.DHCPv6
+		isMessage bool
+	)
+	defer conn.Close()
+	msg, ok := packet.(*dhcpv6.DHCPv6Message)
+	if ok {
+		isMessage = true
+	}
+	for {
+		buf := make([]byte, MaxUDPReceivedPacketSize)
+		n, _, _, _, err := conn.ReadMsgUDP(buf, oobdata)
+		if err != nil {
+			return nil, err
+		}
+		adv, err = dhcpv6.FromBytes(buf[:n])
+		if err != nil {
+			// skip non-DHCP packets
+			continue
+		}
+		if recvMsg, ok := adv.(*dhcpv6.DHCPv6Message); ok && isMessage {
+			// if a regular message, check the transaction ID first
+			// XXX should this unpack relay messages and check the XID of the
+			// inner packet too?
+			if msg.TransactionID() != recvMsg.TransactionID() {
+				// different XID, we don't want this packet for sure
+				continue
+			}
+		}
+		if expectedType == dhcpv6.MessageTypeNone {
+			// just take whatever arrived
+			break
+		} else if adv.Type() == expectedType {
+			break
+		}
+	}
+	return adv, nil
+}
+
+// Solicit sends a Solicit, returns the Solicit, an Advertise (if not nil), and
+// an error if any. The modifiers will be applied to the Solicit before sending
+// it, see modifiers.go
+func (c *Client) Solicit(ifname string, modifiers ...dhcpv6.Modifier) (dhcpv6.DHCPv6, dhcpv6.DHCPv6, error) {
+	solicit, err := dhcpv6.NewSolicitForInterface(ifname)
+	if err != nil {
+		return nil, nil, err
+	}
+	for _, mod := range modifiers {
+		solicit = mod(solicit)
+	}
+	advertise, err := c.sendReceive(ifname, solicit, dhcpv6.MessageTypeNone)
+	return solicit, advertise, err
+}
+
+// Request sends a Request built from an Advertise. It returns the Request, a
+// Reply (if not nil), and an error if any. The modifiers will be applied to
+// the Request before sending it, see modifiers.go
+func (c *Client) Request(ifname string, advertise dhcpv6.DHCPv6, modifiers ...dhcpv6.Modifier) (dhcpv6.DHCPv6, dhcpv6.DHCPv6, error) {
+	request, err := dhcpv6.NewRequestFromAdvertise(advertise)
+	if err != nil {
+		return nil, nil, err
+	}
+	for _, mod := range modifiers {
+		request = mod(request)
+	}
+	reply, err := c.sendReceive(ifname, request, dhcpv6.MessageTypeNone)
+	return request, reply, err
+}
diff --git a/dhcpv6/client6/client_test.go b/dhcpv6/client6/client_test.go
new file mode 100644
index 0000000..1e05a62
--- /dev/null
+++ b/dhcpv6/client6/client_test.go
@@ -0,0 +1,14 @@
+package client6
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestNewClient(t *testing.T) {
+	c := NewClient()
+	require.NotNil(t, c)
+	require.Equal(t, DefaultReadTimeout, c.ReadTimeout)
+	require.Equal(t, DefaultWriteTimeout, c.WriteTimeout)
+}