v6: add BootFileParam getter

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

5 files changed, 34 insertions, 25 deletions

diff --git a/dhcpv6/dhcpv6message.go b/dhcpv6/dhcpv6message.go
index 4e5717f..745a837 100644
--- a/dhcpv6/dhcpv6message.go
+++ b/dhcpv6/dhcpv6message.go
@@ -116,6 +116,18 @@ func (mo MessageOptions) BootFileURL() string {
 	return ""
 }
 
+// BootFileParam returns the Boot File Param option as defined by RFC 5970.
+func (mo MessageOptions) BootFileParam() []string {
+	opt := mo.Options.GetOne(OptionBootfileParam)
+	if opt == nil {
+		return nil
+	}
+	if u, ok := opt.(optBootFileParam); ok {
+		return []string(u)
+	}
+	return nil
+}
+
 // ElapsedTime returns the Elapsed Time option as defined by RFC 3315 Section 22.9.
 //
 // ElapsedTime returns a duration of 0 if the option is not present.
diff --git a/dhcpv6/option_bootfileparam.go b/dhcpv6/option_bootfileparam.go
index 13ec16a..4e2750b 100644
--- a/dhcpv6/option_bootfileparam.go
+++ b/dhcpv6/option_bootfileparam.go
@@ -6,21 +6,21 @@ import (
 	"github.com/u-root/u-root/pkg/uio"
 )
 
-// OptBootFileParam implements the OptionBootfileParam option
-//
-// This module defines the OPT_BOOTFILE_PARAM structure.
-// https://www.ietf.org/rfc/rfc5970.txt (section 3.2)
-type OptBootFileParam []string
+// OptBootFileParam returns a BootfileParam option as defined in RFC 5970
+// Section 3.2.
+func OptBootFileParam(args ...string) Option {
+	return optBootFileParam(args)
+}
 
-var _ Option = OptBootFileParam(nil)
+type optBootFileParam []string
 
 // Code returns the option code
-func (op OptBootFileParam) Code() OptionCode {
+func (optBootFileParam) Code() OptionCode {
 	return OptionBootfileParam
 }
 
 // ToBytes serializes the option and returns it as a sequence of bytes
-func (op OptBootFileParam) ToBytes() []byte {
+func (op optBootFileParam) ToBytes() []byte {
 	buf := uio.NewBigEndianBuffer(nil)
 	for _, param := range op {
 		if len(param) >= 1<<16 {
@@ -41,14 +41,15 @@ func (op OptBootFileParam) ToBytes() []byte {
 	return buf.Data()
 }
 
-func (op OptBootFileParam) String() string {
-	return fmt.Sprintf("OptBootFileParam(%v)", ([]string)(op))
+func (op optBootFileParam) String() string {
+	return fmt.Sprintf("BootFileParam: %v", ([]string)(op))
 }
 
-// ParseOptBootFileParam builds an OptBootFileParam structure from a sequence
+// parseOptBootFileParam builds an OptBootFileParam structure from a sequence
 // of bytes. The input data does not include option code and length bytes.
-func ParseOptBootFileParam(data []byte) (result OptBootFileParam, err error) {
+func parseOptBootFileParam(data []byte) (optBootFileParam, error) {
 	buf := uio.NewBigEndianBuffer(data)
+	var result optBootFileParam
 	for buf.Has(2) {
 		length := buf.Read16()
 		result = append(result, string(buf.CopyN(int(length))))
@@ -56,5 +57,5 @@ func ParseOptBootFileParam(data []byte) (result OptBootFileParam, err error) {
 	if err := buf.FinError(); err != nil {
 		return nil, err
 	}
-	return
+	return result, nil
 }
diff --git a/dhcpv6/option_bootfileparam_test.go b/dhcpv6/option_bootfileparam_test.go
index 80a4386..467f245 100644
--- a/dhcpv6/option_bootfileparam_test.go
+++ b/dhcpv6/option_bootfileparam_test.go
@@ -11,13 +11,13 @@ import (
 
 var (
 	testBootfileParams0Compiled = "\x00\x0eroot=/dev/sda1\x00\x00\x00\x02rw"
-	testBootfileParams1 = []string{
+	testBootfileParams1         = []string{
 		"initrd=http://myserver.mycompany.local/initrd.xz",
 		"",
 		"root=/dev/sda1",
 		"rw",
 		"netconsole=..:\000:.something\000here.::..",
-		string(make([]byte, (1<<16) - 1)),
+		string(make([]byte, (1<<16)-1)),
 	}
 )
 
@@ -41,7 +41,7 @@ func compileTestBootfileParams(t *testing.T, params []string) []byte {
 
 func TestOptBootFileParam(t *testing.T) {
 	expected := string(compileTestBootfileParams(t, testBootfileParams1))
-	opt, err := ParseOptBootFileParam([]byte(expected))
+	opt, err := parseOptBootFileParam([]byte(expected))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -54,7 +54,7 @@ func TestParsedTypeOptBootFileParam(t *testing.T) {
 	tryParse := func(compiled []byte, expected []string) {
 		opt, err := ParseOption(OptionBootfileParam, compiled)
 		require.NoError(t, err)
-		bootfileParamOpt, ok := opt.(OptBootFileParam)
+		bootfileParamOpt, ok := opt.(optBootFileParam)
 		require.True(t, ok, fmt.Sprintf("invalid type: %T instead of %T", opt, bootfileParamOpt))
 		require.Equal(t, compiled, bootfileParamOpt.ToBytes())
 		require.Equal(t, expected, ([]string)(bootfileParamOpt))
diff --git a/dhcpv6/options.go b/dhcpv6/options.go
index 63261c1..23a0ba9 100644
--- a/dhcpv6/options.go
+++ b/dhcpv6/options.go
@@ -80,7 +80,7 @@ func ParseOption(code OptionCode, optData []byte) (Option, error) {
 	case OptionBootfileURL:
 		opt, err = parseOptBootFileURL(optData)
 	case OptionBootfileParam:
-		opt, err = ParseOptBootFileParam(optData)
+		opt, err = parseOptBootFileParam(optData)
 	case OptionClientArchType:
 		opt, err = parseOptClientArchType(optData)
 	case OptionNII:
diff --git a/netboot/netboot.go b/netboot/netboot.go
index 4e1603c..b32f69e 100644
--- a/netboot/netboot.go
+++ b/netboot/netboot.go
@@ -96,7 +96,7 @@ 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.Message
+	var advertise, reply *dhcpv6.Message
 	for _, m := range conversation {
 		switch m.Type() {
 		case dhcpv6.MessageTypeAdvertise:
@@ -118,21 +118,17 @@ func ConversationToNetconf(conversation []dhcpv6.DHCPv6) (*BootConf, error) {
 
 	if u := reply.Options.BootFileURL(); len(u) > 0 {
 		bootconf.BootfileURL = u
-		optionsSource = reply
+		bootconf.BootfileParam = reply.Options.BootFileParam()
 	} else {
 		log.Printf("no bootfile URL option found in REPLY, fallback to ADVERTISE's value")
 		if u := advertise.Options.BootFileURL(); len(u) > 0 {
 			bootconf.BootfileURL = u
-			optionsSource = advertise
+			bootconf.BootfileParam = advertise.Options.BootFileParam()
 		}
 	}
 	if len(bootconf.BootfileURL) == 0 {
 		return nil, errors.New("no bootfile URL option found")
 	}
-
-	if bootfileParamOption := optionsSource.GetOneOption(dhcpv6.OptionBootfileParam); bootfileParamOption != nil {
-		bootconf.BootfileParam = bootfileParamOption.(dhcpv6.OptBootFileParam)
-	}
 	return bootconf, nil
 }