v6: add BootFileURL getter

Signed-off-by: Chris Koch <chrisko@google.com>

5 files changed, 35 insertions, 23 deletions

diff --git a/dhcpv6/dhcpv6message.go b/dhcpv6/dhcpv6message.go
index 400c46a..d099386 100644
--- a/dhcpv6/dhcpv6message.go
+++ b/dhcpv6/dhcpv6message.go
@@ -104,6 +104,18 @@ func (mo MessageOptions) DNS() []net.IP {
 	return nil
 }
 
+// BootFileURL returns the Boot File URL option as defined by RFC 5970.
+func (mo MessageOptions) BootFileURL() string {
+	opt := mo.Options.GetOne(OptionBootfileURL)
+	if opt == nil {
+		return ""
+	}
+	if u, ok := opt.(optBootFileURL); ok {
+		return string(u)
+	}
+	return ""
+}
+
 // Message represents a DHCPv6 Message as defined by RFC 3315 Section 6.
 type Message struct {
 	MessageType   MessageType
diff --git a/dhcpv6/option_bootfileurl.go b/dhcpv6/option_bootfileurl.go
index d37a186..695f164 100644
--- a/dhcpv6/option_bootfileurl.go
+++ b/dhcpv6/option_bootfileurl.go
@@ -4,30 +4,29 @@ import (
 	"fmt"
 )
 
-// OptBootFileURL implements the OptionBootfileURL option
-//
-// This module defines the OptBootFileURL structure.
-// https://www.ietf.org/rfc/rfc5970.txt
-type OptBootFileURL string
+// OptBootFileURL returns a OptionBootfileURL as defined by RFC 5970.
+func OptBootFileURL(url string) Option {
+	return optBootFileURL(url)
+}
 
-var _ Option = OptBootFileURL("")
+type optBootFileURL string
 
 // Code returns the option code
-func (op OptBootFileURL) Code() OptionCode {
+func (op optBootFileURL) Code() OptionCode {
 	return OptionBootfileURL
 }
 
 // ToBytes serializes the option and returns it as a sequence of bytes
-func (op OptBootFileURL) ToBytes() []byte {
+func (op optBootFileURL) ToBytes() []byte {
 	return []byte(op)
 }
 
-func (op OptBootFileURL) String() string {
-	return fmt.Sprintf("OptBootFileURL(%s)", string(op))
+func (op optBootFileURL) String() string {
+	return fmt.Sprintf("BootFileURL: %s", string(op))
 }
 
-// ParseOptBootFileURL builds an OptBootFileURL structure from a sequence
+// parseOptBootFileURL builds an optBootFileURL structure from a sequence
 // of bytes. The input data does not include option code and length bytes.
-func ParseOptBootFileURL(data []byte) (OptBootFileURL, error) {
-	return OptBootFileURL(string(data)), nil
+func parseOptBootFileURL(data []byte) (optBootFileURL, error) {
+	return optBootFileURL(string(data)), nil
 }
diff --git a/dhcpv6/option_bootfileurl_test.go b/dhcpv6/option_bootfileurl_test.go
index 80cdbf0..ac45ef5 100644
--- a/dhcpv6/option_bootfileurl_test.go
+++ b/dhcpv6/option_bootfileurl_test.go
@@ -9,7 +9,7 @@ import (
 
 func TestOptBootFileURL(t *testing.T) {
 	expected := "https://insomniac.slackware.it"
-	opt, err := ParseOptBootFileURL([]byte(expected))
+	opt, err := parseOptBootFileURL([]byte(expected))
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/dhcpv6/options.go b/dhcpv6/options.go
index 0db7ebd..9d0ff9d 100644
--- a/dhcpv6/options.go
+++ b/dhcpv6/options.go
@@ -78,7 +78,7 @@ func ParseOption(code OptionCode, optData []byte) (Option, error) {
 	case OptionFQDN:
 		opt, err = ParseOptFQDN(optData)
 	case OptionBootfileURL:
-		opt, err = ParseOptBootFileURL(optData)
+		opt, err = parseOptBootFileURL(optData)
 	case OptionBootfileParam:
 		opt, err = ParseOptBootFileParam(optData)
 	case OptionClientArchType:
diff --git a/netboot/netboot.go b/netboot/netboot.go
index e771e3d..4e1603c 100644
--- a/netboot/netboot.go
+++ b/netboot/netboot.go
@@ -96,13 +96,13 @@ func RequestNetbootv4(ifname string, timeout time.Duration, retries int, modifie
 // ConversationToNetconf extracts network configuration and boot file URL from a
 // DHCPv6 4-way conversation and returns them, or an error if any.
 func ConversationToNetconf(conversation []dhcpv6.DHCPv6) (*BootConf, error) {
-	var advertise, reply, optionsSource dhcpv6.DHCPv6
+	var advertise, reply, optionsSource *dhcpv6.Message
 	for _, m := range conversation {
 		switch m.Type() {
 		case dhcpv6.MessageTypeAdvertise:
-			advertise = m
+			advertise = m.(*dhcpv6.Message)
 		case dhcpv6.MessageTypeReply:
-			reply = m
+			reply = m.(*dhcpv6.Message)
 		}
 	}
 	if reply == nil {
@@ -110,24 +110,25 @@ func ConversationToNetconf(conversation []dhcpv6.DHCPv6) (*BootConf, error) {
 	}
 
 	bootconf := &BootConf{}
-	netconf, err := GetNetConfFromPacketv6(reply.(*dhcpv6.Message))
+	netconf, err := GetNetConfFromPacketv6(reply)
 	if err != nil {
 		return nil, fmt.Errorf("cannot get netconf from packet: %v", err)
 	}
 	bootconf.NetConf = *netconf
 
-	if reply.GetOneOption(dhcpv6.OptionBootfileURL) != nil {
+	if u := reply.Options.BootFileURL(); len(u) > 0 {
+		bootconf.BootfileURL = u
 		optionsSource = reply
 	} else {
 		log.Printf("no bootfile URL option found in REPLY, fallback to ADVERTISE's value")
-		if advertise.GetOneOption(dhcpv6.OptionBootfileURL) != nil {
+		if u := advertise.Options.BootFileURL(); len(u) > 0 {
+			bootconf.BootfileURL = u
 			optionsSource = advertise
 		}
 	}
-	if optionsSource == nil {
+	if len(bootconf.BootfileURL) == 0 {
 		return nil, errors.New("no bootfile URL option found")
 	}
-	bootconf.BootfileURL = string(optionsSource.GetOneOption(dhcpv6.OptionBootfileURL).(dhcpv6.OptBootFileURL))
 
 	if bootfileParamOption := optionsSource.GetOneOption(dhcpv6.OptionBootfileParam); bootfileParamOption != nil {
 		bootconf.BootfileParam = bootfileParamOption.(dhcpv6.OptBootFileParam)