3 files changed, 131 insertions, 5 deletions
diff --git a/dhcpv4/option_relay_agent_information.go b/dhcpv4/option_relay_agent_information.go
new file mode 100644
index 0000000..844c4bc
--- /dev/null
+++ b/dhcpv4/option_relay_agent_information.go
@@ -0,0 +1,74 @@
+package dhcpv4
+
+import "fmt"
+
+// This option implements the relay agent information option
+// https://tools.ietf.org/html/rfc3046
+
+// OptRelayAgentInformation is a "container" option for specific agent-supplied
+// sub-options.
+type OptRelayAgentInformation struct {
+	Options []Option
+}
+
+// Parse returns a new OptRelayAgentInformation from a byte stream, or error if
+// any.
+func ParseOptRelayAgentInformation(data []byte) (*OptRelayAgentInformation, error) {
+	if len(data) < 4 {
+		return nil, ErrShortByteStream
+	}
+	code := OptionCode(data[0])
+	if code != OptionRelayAgentInformation {
+		return nil, fmt.Errorf("expected code %v, got %v", OptionRelayAgentInformation, code)
+	}
+	length := int(data[1])
+	if len(data) < 2+length {
+		return nil, ErrShortByteStream
+	}
+	options, err := OptionsFromBytesWithParser(data[2:length+2], relayParseOption)
+	if err != nil {
+		return nil, err
+	}
+	return &OptRelayAgentInformation{Options: options}, nil
+}
+
+func relayParseOption(data []byte) (Option, error) {
+	if len(data) < 2 {
+		return nil, ErrShortByteStream
+	}
+	code := OptionCode(data[0])
+	length := int(data[1])
+	if len(data) < 2+length {
+		return nil, ErrShortByteStream
+	}
+	return &OptionGeneric{OptionCode: code, Data: data[2:length+2]}, nil
+}
+
+// Code returns the option code.
+func (o *OptRelayAgentInformation) Code() OptionCode {
+	return OptionRelayAgentInformation
+}
+
+// ToBytes returns a serialized stream of bytes for this option.
+func (o *OptRelayAgentInformation) ToBytes() []byte {
+	ret := []byte{byte(o.Code()), byte(o.Length())}
+	for _, opt := range o.Options {
+		ret = append(ret, opt.ToBytes()...)
+	}
+	return ret
+}
+
+// String returns a human-readable string for this option.
+func (o *OptRelayAgentInformation) String() string {
+	return fmt.Sprintf("Relay Agent Information -> [%v]", o.Options)
+}
+
+// Length returns the length of the data portion (excluding option code and byte
+// for length, if any).
+func (o *OptRelayAgentInformation) Length() int {
+	l := 0
+	for _, opt := range o.Options {
+		l += 2 + opt.Length()
+	}
+	return l
+}
diff --git a/dhcpv4/option_relay_agent_information_test.go b/dhcpv4/option_relay_agent_information_test.go
new file mode 100644
index 0000000..e3310e9
--- /dev/null
+++ b/dhcpv4/option_relay_agent_information_test.go
@@ -0,0 +1,41 @@
+package dhcpv4
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseOptRelayAgentInformation(t *testing.T) {
+	data := []byte{
+		byte(OptionRelayAgentInformation),
+		13,
+		1, 5, 'l', 'i', 'n', 'u', 'x',
+		2, 4, 'b', 'o', 'o', 't',
+	}
+	opt, err := ParseOptRelayAgentInformation(data)
+	require.NoError(t, err)
+
+	circuit, ok := opt.Options[0].(*OptionGeneric)
+	require.True(t, ok)
+	remote, ok := opt.Options[1].(*OptionGeneric)
+	require.True(t, ok)
+	require.Equal(t, circuit.Data, []byte("linux"))
+	require.Equal(t, remote.Data, []byte("boot"))
+}
+
+func TestParseOptRelayAgentInformationToBytes(t *testing.T) {
+	opt := OptRelayAgentInformation{}
+	opt1 := &OptionGeneric{OptionCode: 1, Data: []byte("linux")}
+	opt.Options = append(opt.Options, opt1)
+	opt2 := &OptionGeneric{OptionCode: 2, Data: []byte("boot")}
+	opt.Options = append(opt.Options, opt2)
+	data := opt.ToBytes()
+	expected := []byte{
+		byte(OptionRelayAgentInformation),
+		13,
+		1, 5, 'l', 'i', 'n', 'u', 'x',
+		2, 4, 'b', 'o', 'o', 't',
+	}
+	require.Equal(t, expected, data)
+}
diff --git a/dhcpv4/options.go b/dhcpv4/options.go
index 6256ef7..b117728 100644
--- a/dhcpv4/options.go
+++ b/dhcpv4/options.go
@@ -50,6 +50,8 @@ func ParseOption(data []byte) (Option, error) {
 		opt, err = ParseOptHostName(data)
 	case OptionDomainName:
 		opt, err = ParseOptDomainName(data)
+	case OptionRootPath:
+		opt, err = ParseOptRootPath(data)
 	case OptionBroadcastAddress:
 		opt, err = ParseOptBroadcastAddress(data)
 	case OptionNTPServers:
@@ -74,14 +76,14 @@ func ParseOption(data []byte) (Option, error) {
 		opt, err = ParseOptBootfileName(data)
 	case OptionUserClassInformation:
 		opt, err = ParseOptUserClass(data)
+	case OptionRelayAgentInformation:
+		opt, err = ParseOptRelayAgentInformation(data)
 	case OptionClientSystemArchitectureType:
 		opt, err = ParseOptClientArchType(data)
-	case OptionVendorIdentifyingVendorClass:
-		opt, err = ParseOptVIVC(data)
 	case OptionDNSDomainSearchList:
 		opt, err = ParseOptDomainSearch(data)
-	case OptionRootPath:
-		opt, err = ParseOptRootPath(data)
+	case OptionVendorIdentifyingVendorClass:
+		opt, err = ParseOptVIVC(data)
 	default:
 		opt, err = ParseOptionGeneric(data)
 	}
@@ -112,6 +114,15 @@ func OptionsFromBytes(data []byte) ([]Option, error) {
 // and builds a list of options from it. The sequence should not contain the
 // DHCP magic cookie. Returns an error if any invalid option or length is found.
 func OptionsFromBytesWithoutMagicCookie(data []byte) ([]Option, error) {
+	return OptionsFromBytesWithParser(data, ParseOption)
+}
+
+// OptionParser is a function signature for option parsing
+type OptionParser func(data []byte) (Option, error)
+
+// OptionsFromBytesWithParser parses Options from byte sequences using the
+// parsing function that is passed in as a paremeter
+func OptionsFromBytesWithParser(data []byte, parser OptionParser) ([]Option, error) {
 	options := make([]Option, 0, 10)
 	idx := 0
 	for {
@@ -122,7 +133,7 @@ func OptionsFromBytesWithoutMagicCookie(data []byte) ([]Option, error) {
 		if idx > len(data) {
 			return nil, errors.New("read past the end of options")
 		}
-		opt, err := ParseOption(data[idx:])
+		opt, err := parser(data[idx:])
 		idx++
 		if err != nil {
 			return nil, err