dhcpv6: easier option parsing

- move option parsing to uio buffer library.
- move option code and length reading into FromBytes rather than
implementing it in each OptionParser.

1 files changed, 18 insertions, 18 deletions

diff --git a/dhcpv6/option_remoteid.go b/dhcpv6/option_remoteid.go
index 9d249a7..6b1831d 100644
--- a/dhcpv6/option_remoteid.go
+++ b/dhcpv6/option_remoteid.go
@@ -1,13 +1,14 @@
 package dhcpv6
 
-// This module defines the OptRemoteId structure.
-// https://www.ietf.org/rfc/rfc4649.txt
-
 import (
-	"encoding/binary"
 	"fmt"
+
+	"github.com/u-root/u-root/pkg/uio"
 )
 
+// OptRemoteId implemens the Remote ID option.
+//
+// https://www.ietf.org/rfc/rfc4649.txt
 type OptRemoteId struct {
 	enterpriseNumber uint32
 	remoteId         []byte
@@ -17,13 +18,14 @@ func (op *OptRemoteId) Code() OptionCode {
 	return OptionRemoteID
 }
 
+// ToBytes serializes this option to a byte stream.
 func (op *OptRemoteId) ToBytes() []byte {
-	buf := make([]byte, 8)
-	binary.BigEndian.PutUint16(buf[0:2], uint16(OptionRemoteID))
-	binary.BigEndian.PutUint16(buf[2:4], uint16(op.Length()))
-	binary.BigEndian.PutUint32(buf[4:8], uint32(op.enterpriseNumber))
-	buf = append(buf, op.remoteId...)
-	return buf
+	buf := uio.NewBigEndianBuffer(nil)
+	buf.Write16(uint16(OptionRemoteID))
+	buf.Write16(uint16(op.Length()))
+	buf.Write32(uint32(op.enterpriseNumber))
+	buf.WriteBytes(op.remoteId)
+	return buf.Data()
 }
 
 func (op *OptRemoteId) EnterpriseNumber() uint32 {
@@ -52,14 +54,12 @@ func (op *OptRemoteId) String() string {
 	)
 }
 
-// build an OptRemoteId structure from a sequence of bytes.
+// ParseOptRemoteId builds an OptRemoteId structure from a sequence of bytes.
 // The input data does not include option code and length bytes.
 func ParseOptRemoteId(data []byte) (*OptRemoteId, error) {
-	opt := OptRemoteId{}
-	if len(data) < 4 {
-		return nil, fmt.Errorf("Invalid remote id data length. Expected at least 4 bytes, got %v", len(data))
-	}
-	opt.enterpriseNumber = binary.BigEndian.Uint32(data[:4])
-	opt.remoteId = append([]byte(nil), data[4:]...)
-	return &opt, nil
+	var opt OptRemoteId
+	buf := uio.NewBigEndianBuffer(data)
+	opt.enterpriseNumber = buf.Read32()
+	opt.remoteId = buf.ReadAll()
+	return &opt, buf.FinError()
 }