dhcpv6: add DHCPv4-over-DHCPv6 support

Add message types, options, and modifier for handling DHCPv4-over-DHCPv6.

Refer to RFC 7341

Signed-off-by: Mikael Magnusson <mikma@users.sourceforge.net>

1 files changed, 105 insertions, 0 deletions

diff --git a/dhcpv6/option_dhcpv4_msg_test.go b/dhcpv6/option_dhcpv4_msg_test.go
new file mode 100644
index 0000000..1ffa17a
--- /dev/null
+++ b/dhcpv6/option_dhcpv4_msg_test.go
@@ -0,0 +1,105 @@
+package dhcpv6
+
+import (
+	"bytes"
+	"net"
+	"testing"
+
+	"github.com/insomniacslk/dhcp/dhcpv4"
+	"github.com/insomniacslk/dhcp/iana"
+	"github.com/stretchr/testify/require"
+)
+
+var magicCookie = [4]byte{99, 130, 83, 99}
+
+func TestParseOptDHCPv4Msg(t *testing.T) {
+	data := []byte{
+		1,                      // dhcp request
+		1,                      // ethernet hw type
+		6,                      // hw addr length
+		3,                      // hop count
+		0xaa, 0xbb, 0xcc, 0xdd, // transaction ID, big endian (network)
+		0, 3, // number of seconds
+		0, 1, // broadcast
+		0, 0, 0, 0, // client IP address
+		0, 0, 0, 0, // your IP address
+		0, 0, 0, 0, // server IP address
+		0, 0, 0, 0, // gateway IP address
+		0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // client MAC address + padding
+	}
+
+	// server host name
+	expectedHostname := []byte{}
+	for i := 0; i < 64; i++ {
+		expectedHostname = append(expectedHostname, 0)
+	}
+	data = append(data, expectedHostname...)
+	// boot file name
+	expectedBootfilename := []byte{}
+	for i := 0; i < 128; i++ {
+		expectedBootfilename = append(expectedBootfilename, 0)
+	}
+	data = append(data, expectedBootfilename...)
+	// magic cookie, then no options
+	data = append(data, magicCookie[:]...)
+
+	opt, err := ParseOptDHCPv4Msg(data)
+	d := opt.Msg
+	require.NoError(t, err)
+	require.Equal(t, d.OpCode, dhcpv4.OpcodeBootRequest)
+	require.Equal(t, d.HWType, iana.HWTypeEthernet)
+	require.Equal(t, d.HopCount, byte(3))
+	require.Equal(t, d.TransactionID, dhcpv4.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))
+	require.True(t, d.YourIPAddr.Equal(net.IPv4zero))
+	require.True(t, d.GatewayIPAddr.Equal(net.IPv4zero))
+	require.Equal(t, d.ClientHWAddr, net.HardwareAddr{0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff})
+	require.Equal(t, d.ServerHostName, "")
+	require.Equal(t, d.BootFileName, "")
+	// no need to check Magic Cookie as it is already validated in FromBytes
+	// above
+}
+
+func TestOptDHCPv4MsgToBytes(t *testing.T) {
+	// the following bytes match what dhcpv4.New would create. Keep them in
+	// sync!
+	expected := []byte{
+		1,                      // Opcode BootRequest
+		1,                      // HwType Ethernet
+		6,                      // HwAddrLen
+		0,                      // HopCount
+		0x11, 0x22, 0x33, 0x44, // TransactionID
+		0, 0, // NumSeconds
+		0, 0, // Flags
+		0, 0, 0, 0, // ClientIPAddr
+		0, 0, 0, 0, // YourIPAddr
+		0, 0, 0, 0, // ServerIPAddr
+		0, 0, 0, 0, // GatewayIPAddr
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // ClientHwAddr
+	}
+	// ServerHostName
+	expected = append(expected, bytes.Repeat([]byte{0}, 64)...)
+	// BootFileName
+	expected = append(expected, bytes.Repeat([]byte{0}, 128)...)
+
+	// Magic Cookie
+	expected = append(expected, magicCookie[:]...)
+
+	// Minimum message length padding.
+	//
+	// 236 + 4 byte cookie + 59 bytes padding + 1 byte end.
+	expected = append(expected, bytes.Repeat([]byte{0}, 59)...)
+
+	// End
+	expected = append(expected, 0xff)
+
+	d, err := dhcpv4.New()
+	require.NoError(t, err)
+	// fix TransactionID to match the expected one, since it's randomly
+	// generated in New()
+	d.TransactionID = dhcpv4.TransactionID{0x11, 0x22, 0x33, 0x44}
+	opt := OptDHCPv4Msg{Msg: d}
+	require.Equal(t, expected, opt.ToBytes())
+}