dhcpv4: nicer API for option parsing.

From:
  r := d.GetOneOption(OptionRouter).(*OptRouter).Routers
  d.UpdateOption(&OptRouter{Routers: []net.IP{net.IP{192, 168, 0, 1}}})

To:
  r := GetRouter(d.Options)
  d.UpdateOption(OptRouter(net.IP{192, 168, 0, 1}, ...))

1 files changed, 38 insertions, 24 deletions

diff --git a/dhcpv4/option_vivc.go b/dhcpv4/option_vivc.go
index b6efab9..509ba80 100644
--- a/dhcpv4/option_vivc.go
+++ b/dhcpv4/option_vivc.go
@@ -10,39 +10,53 @@ import (
 // VIVCIdentifier implements the vendor-identifying vendor class option
 // described by RFC 3925.
 type VIVCIdentifier struct {
+	// EntID is the enterprise ID.
 	EntID uint32
 	Data  []byte
 }
 
-// OptVIVC represents the DHCP message type option.
-type OptVIVC struct {
-	Identifiers []VIVCIdentifier
+// OptVIVC returns a new vendor-identifying vendor class option.
+//
+// The option is described by RFC 3925.
+func OptVIVC(identifiers ...VIVCIdentifier) Option {
+	return Option{
+		Code:  OptionVendorIdentifyingVendorClass,
+		Value: VIVCIdentifiers(identifiers),
+	}
 }
 
-// ParseOptVIVC contructs an OptVIVC tsruct from a sequence of bytes and returns
-// it, or an error.
-func ParseOptVIVC(data []byte) (*OptVIVC, error) {
-	buf := uio.NewBigEndianBuffer(data)
+// GetVIVC returns the vendor-identifying vendor class option in o if present.
+func GetVIVC(o Options) VIVCIdentifiers {
+	v := o.Get(OptionVendorIdentifyingVendorClass)
+	if v == nil {
+		return nil
+	}
+	var ids VIVCIdentifiers
+	if err := ids.FromBytes(v); err != nil {
+		return nil
+	}
+	return ids
+}
+
+// VIVCIdentifiers implements encoding and decoding methods for a DHCP option
+// described in RFC 3925.
+type VIVCIdentifiers []VIVCIdentifier
 
-	var ids []VIVCIdentifier
+// FromBytes parses data into ids per RFC 3925.
+func (ids *VIVCIdentifiers) FromBytes(data []byte) error {
+	buf := uio.NewBigEndianBuffer(data)
 	for buf.Has(5) {
 		entID := buf.Read32()
 		idLen := int(buf.Read8())
-		ids = append(ids, VIVCIdentifier{EntID: entID, Data: buf.CopyN(idLen)})
+		*ids = append(*ids, VIVCIdentifier{EntID: entID, Data: buf.CopyN(idLen)})
 	}
-
-	return &OptVIVC{Identifiers: ids}, buf.FinError()
-}
-
-// Code returns the option code.
-func (o *OptVIVC) Code() OptionCode {
-	return OptionVendorIdentifyingVendorClass
+	return buf.FinError()
 }
 
 // ToBytes returns a serialized stream of bytes for this option.
-func (o *OptVIVC) ToBytes() []byte {
+func (ids VIVCIdentifiers) ToBytes() []byte {
 	buf := uio.NewBigEndianBuffer(nil)
-	for _, id := range o.Identifiers {
+	for _, id := range ids {
 		buf.Write32(id.EntID)
 		buf.Write8(uint8(len(id.Data)))
 		buf.WriteBytes(id.Data)
@@ -51,13 +65,13 @@ func (o *OptVIVC) ToBytes() []byte {
 }
 
 // String returns a human-readable string for this option.
-func (o *OptVIVC) String() string {
+func (ids VIVCIdentifiers) String() string {
+	if len(ids) == 0 {
+		return ""
+	}
 	buf := bytes.Buffer{}
-	fmt.Fprintf(&buf, "Vendor-Identifying Vendor Class ->")
-
-	for _, id := range o.Identifiers {
+	for _, id := range ids {
 		fmt.Fprintf(&buf, " %d:'%s',", id.EntID, id.Data)
 	}
-
-	return buf.String()[:buf.Len()-1]
+	return buf.String()[1 : buf.Len()-1]
 }