1 files changed, 125 insertions, 0 deletions
diff --git a/dhcpv6/options/options.go b/dhcpv6/options/options.go
new file mode 100644
index 0000000..6b587dd
--- /dev/null
+++ b/dhcpv6/options/options.go
@@ -0,0 +1,125 @@
+package options
+
+import (
+	"encoding/binary"
+	"fmt"
+)
+
+type OptionCode uint16
+
+type Option interface {
+	Code() OptionCode
+	ToBytes() []byte
+	Length() int
+	String() string
+}
+
+type OptionGeneric struct {
+	OptionCode OptionCode
+	OptionData []byte
+}
+
+func (og *OptionGeneric) Code() OptionCode {
+	return og.OptionCode
+}
+
+func (og *OptionGeneric) ToBytes() []byte {
+	var ret []byte
+	codeBytes := make([]byte, 2)
+	binary.BigEndian.PutUint16(codeBytes, uint16(og.OptionCode))
+	ret = append(ret, codeBytes...)
+	lengthBytes := make([]byte, 2)
+	binary.BigEndian.PutUint16(lengthBytes, uint16(len(og.OptionData)))
+	ret = append(ret, lengthBytes...)
+	ret = append(ret, og.OptionData...)
+	return ret
+}
+
+func (og *OptionGeneric) String() string {
+	code, ok := OptionCodeToString[og.OptionCode]
+	if !ok {
+		code = "UnknownOption"
+	}
+	return fmt.Sprintf("%v -> %v", code, og.OptionData)
+}
+
+func (og *OptionGeneric) Length() int {
+	return len(og.OptionData)
+}
+
+func ParseOption(dataStart []byte) (Option, error) {
+	// Parse a sequence of bytes as a single DHCPv6 option.
+	// Returns the option structure, or an error if any.
+	if len(dataStart) < 4 {
+		return nil, fmt.Errorf("Invalid DHCPv6 option: less than 4 bytes")
+	}
+	code := OptionCode(binary.BigEndian.Uint16(dataStart[:2]))
+	length := int(binary.BigEndian.Uint16(dataStart[2:4]))
+	if len(dataStart) < length+4 {
+		return nil, fmt.Errorf("Invalid option length. Declared %v, actual %v",
+			length, len(dataStart)-4,
+		)
+	}
+	var (
+		err error
+		opt Option
+	)
+	optData := dataStart[4 : 4+length]
+	switch code {
+	case OPTION_CLIENTID:
+		opt, err = ParseOptClientId(optData)
+	case OPTION_SERVERID:
+		opt, err = ParseOptServerId(optData)
+	case OPTION_ELAPSED_TIME:
+		opt, err = ParseOptElapsedTime(optData)
+	case OPTION_ORO:
+		opt, err = ParseOptRequestedOption(optData)
+	case DNS_RECURSIVE_NAME_SERVER:
+		opt, err = ParseOptDNSRecursiveNameServer(optData)
+	case DOMAIN_SEARCH_LIST:
+		opt, err = ParseOptDomainSearchList(optData)
+	case OPTION_IA_NA:
+		opt, err = ParseOptIANA(optData)
+	case OPTION_IA_PD:
+		opt, err = ParseOptIAForPrefixDelegation(optData)
+	case OPTION_IAADDR:
+		opt, err = ParseOptIAAddress(optData)
+	case OPTION_IAPREFIX:
+		opt, err = ParseOptIAPrefix(optData)
+	case OPTION_STATUS_CODE:
+		opt, err = ParseOptStatusCode(optData)
+	default:
+		opt = &OptionGeneric{OptionCode: code, OptionData: optData}
+	}
+	if err != nil {
+		return nil, err
+	}
+	return opt, nil
+}
+
+func FromBytes(data []byte) ([]Option, error) {
+	// Parse a sequence of bytes until the end and build a list of options from
+	// it. Returns an error if any invalid option or length is found.
+	if len(data) < 4 {
+		// cannot be shorter than option code (2 bytes) + length (2 bytes)
+		return nil, fmt.Errorf("Invalid options: shorter than 4 bytes")
+	}
+	options := make([]Option, 0, 10)
+	idx := 0
+	for {
+		if idx == len(data) {
+			break
+		}
+		if idx > len(data) {
+			// this should never happen
+			return nil, fmt.Errorf("Error: reading past the end of options")
+		}
+		opt, err := ParseOption(data[idx:])
+		if err != nil {
+			return nil, err
+		}
+		options = append(options, opt)
+		idx += opt.Length() + 4 // 4 bytes for type + length
+	}
+	return options, nil
+}