Add TFTP server name option (#92)

3 files changed, 120 insertions, 0 deletions

diff --git a/dhcpv4/option_tftp_server_name.go b/dhcpv4/option_tftp_server_name.go
new file mode 100644
index 0000000..b4029e1
--- /dev/null
+++ b/dhcpv4/option_tftp_server_name.go
@@ -0,0 +1,54 @@
+package dhcpv4
+
+import (
+	"fmt"
+)
+
+// This option implements the TFTP server name option.
+// https://tools.ietf.org/html/rfc2132
+
+// OptTFTPServerName implements the TFTP server name option.
+type OptTFTPServerName struct {
+	TFTPServerName []byte
+}
+
+// Code returns the option code
+func (op *OptTFTPServerName) Code() OptionCode {
+	return OptionTFTPServerName
+}
+
+// ToBytes serializes the option and returns it as a sequence of bytes
+func (op *OptTFTPServerName) ToBytes() []byte {
+	return append([]byte{byte(op.Code()), byte(op.Length())}, op.TFTPServerName...)
+}
+
+// Length returns the option length in bytes
+func (op *OptTFTPServerName) Length() int {
+	return len(op.TFTPServerName)
+}
+
+func (op *OptTFTPServerName) String() string {
+	return fmt.Sprintf("OptTFTPServerName{TFTPServerName=%s}", op.TFTPServerName)
+}
+
+// ParseOptTFTPServerName returns a new OptTFTPServerName fomr a byte stream or error if any
+func ParseOptTFTPServerName(data []byte) (*OptTFTPServerName, error) {
+	if len(data) < 3 {
+		return nil, ErrShortByteStream
+	}
+	code := OptionCode(data[0])
+	if code != OptionTFTPServerName {
+		return nil, fmt.Errorf("ParseOptTFTPServerName: invalid code: %v; want %v",
+			code, OptionTFTPServerName)
+	}
+	length := int(data[1])
+	if length < 1 {
+		return nil, fmt.Errorf("TFTP server name has invalid length of %d", length)
+	}
+	TFTPServerNameData := data[2:]
+	if len(TFTPServerNameData) < length {
+		return nil, fmt.Errorf("ParseOptTFTPServerName: short data: %d bytes; want %d",
+			len(TFTPServerNameData), length)
+	}
+	return &OptTFTPServerName{TFTPServerName: TFTPServerNameData[:length]}, nil
+}
diff --git a/dhcpv4/option_tftp_server_name_test.go b/dhcpv4/option_tftp_server_name_test.go
new file mode 100644
index 0000000..caddf95
--- /dev/null
+++ b/dhcpv4/option_tftp_server_name_test.go
@@ -0,0 +1,60 @@
+package dhcpv4
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestOptTFTPServerNameCode(t *testing.T) {
+	opt := OptTFTPServerName{}
+	require.Equal(t, OptionTFTPServerName, opt.Code())
+}
+
+func TestOptTFTPServerNameToBytes(t *testing.T) {
+	opt := OptTFTPServerName{
+		TFTPServerName: []byte("linuxboot"),
+	}
+	data := opt.ToBytes()
+	expected := []byte{
+		66, // OptionTFTPServerName
+		9,  // length
+		'l', 'i', 'n', 'u', 'x', 'b', 'o', 'o', 't',
+	}
+	require.Equal(t, expected, data)
+}
+
+func TestParseOptTFTPServerName(t *testing.T) {
+	expected := []byte{
+		66, 9, 'l', 'i', 'n', 'u', 'x', 'b', 'o', 'o', 't',
+	}
+	opt, err := ParseOptTFTPServerName(expected)
+	require.NoError(t, err)
+	require.Equal(t, 9, opt.Length())
+	require.Equal(t, "linuxboot", string(opt.TFTPServerName))
+}
+
+func TestParseOptTFTPServerNameZeroLength(t *testing.T) {
+	expected := []byte{
+		66, 0,
+	}
+	_, err := ParseOptTFTPServerName(expected)
+	require.Error(t, err)
+}
+
+func TestParseOptTFTPServerNameInvalidLength(t *testing.T) {
+	expected := []byte{
+		66, 9, 'l', 'i', 'n', 'u', 'x', 'b',
+	}
+	_, err := ParseOptTFTPServerName(expected)
+	require.Error(t, err)
+}
+
+func TestParseOptTFTPServerNameShortLength(t *testing.T) {
+	expected := []byte{
+		66, 4, 'l', 'i', 'n', 'u', 'x',
+	}
+	opt, err := ParseOptTFTPServerName(expected)
+	require.NoError(t, err)
+	require.Equal(t, []byte("linu"), opt.TFTPServerName)
+}
diff --git a/dhcpv4/options.go b/dhcpv4/options.go
index 2bd26a5..5e6da80 100644
--- a/dhcpv4/options.go
+++ b/dhcpv4/options.go
@@ -60,6 +60,12 @@ func ParseOption(data []byte) (Option, error) {
 		opt, err = ParseOptDomainNameServer(data)
 	case OptionVendorIdentifyingVendorClass:
 		opt, err = ParseOptVIVC(data)
+	case OptionTFTPServerName:
+		opt, err = ParseOptTFTPServerName(data)
+	case OptionBootfileName:
+		opt, err = ParseOptBootfileName(data)
+	case OptionUserClassInformation:
+		opt, err = ParseOptUserClass(data)
 	default:
 		opt, err = ParseOptionGeneric(data)
 	}