Adding module for DHCPv6 Vendor Options (Opt 17) (#130)

3 files changed, 230 insertions, 1 deletions

diff --git a/dhcpv6/option_vendor_opts.go b/dhcpv6/option_vendor_opts.go
new file mode 100644
index 0000000..a2281e3
--- /dev/null
+++ b/dhcpv6/option_vendor_opts.go
@@ -0,0 +1,117 @@
+package dhcpv6
+
+/*
+ This module defines the OptVendorOpts structure.
+ https://tools.ietf.org/html/rfc3315#section-22.17
+
+				Option 17
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |      OPTION_VENDOR_OPTS       |           option-len          |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                       enterprise-number                       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      .                                                               .
+      .                   option-data (sub-options)                   .
+      .                                                               .
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+				Sub-Option
+	 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+	|          opt-code             |             option-len        |
+	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+	.                                                               .
+	.                          option-data                          .
+	.                                                               .
+	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+*/
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+)
+
+// OptVendorOpts represents a DHCPv6 Status Code option
+type OptVendorOpts struct {
+	EnterpriseNumber uint32
+	VendorOpts       []Option
+}
+
+// Code returns the option code
+func (op *OptVendorOpts) Code() OptionCode {
+	return OptionVendorOpts
+}
+
+// ToBytes serializes the option and returns it as a sequence of bytes
+func (op *OptVendorOpts) ToBytes() []byte {
+	buf := make([]byte, 8)
+	binary.BigEndian.PutUint16(buf[0:2], uint16(OptionVendorOpts))
+	binary.BigEndian.PutUint16(buf[2:4], uint16(op.Length()))
+	binary.BigEndian.PutUint32(buf[4:8], uint32(op.EnterpriseNumber))
+	for _, opt := range op.VendorOpts {
+		buf = append(buf, opt.ToBytes()...)
+	}
+	return buf
+}
+
+// Length returns the option length
+func (op *OptVendorOpts) Length() int {
+	l := 4 // 4 bytes for Enterprise Number
+	for _, opt := range op.VendorOpts {
+		l += 4 + opt.Length() // 4 bytes for Code and Length from Vendor
+	}
+	return l
+}
+
+// String returns a string representation of the VendorOpts data
+func (op *OptVendorOpts) String() string {
+	return fmt.Sprintf("OptVendorOpts{enterprisenum=%v, vendorOpts=%v}",
+		op.EnterpriseNumber, op.VendorOpts,
+	)
+}
+
+// ParseOptVendorOpts builds an OptVendorOpts structure from a sequence of bytes.
+// The input data does not include option code and length bytes.
+func ParseOptVendorOpts(data []byte) (*OptVendorOpts, error) {
+	opt := OptVendorOpts{}
+	if len(data) < 4 {
+		return nil, fmt.Errorf("Invalid vendor opts data length. Expected at least 4 bytes, got %v", len(data))
+	}
+	opt.EnterpriseNumber = binary.BigEndian.Uint32(data[:4])
+
+	var err error
+	opt.VendorOpts, err = OptionsFromBytesWithParser(data[4:], vendParseOption)
+	if err != nil {
+		return nil, err
+	}
+	return &opt, nil
+}
+
+// vendParseOption builds a GenericOption from a slice of bytes
+// We cannot use the exisitng ParseOption function in options.go because the
+// sub-options include codes specific to each vendor. There are overlaps in these
+// codes with RFC standard codes.
+func vendParseOption(dataStart []byte) (Option, error) {
+	// Parse a sequence of bytes as a single DHCPv6 option.
+	// Returns the option structure, or an error if any.
+
+	if len(dataStart) < 4 {
+		return nil, fmt.Errorf("Invalid DHCPv6 vendor option: less than 4 bytes")
+	}
+	code := OptionCode(binary.BigEndian.Uint16(dataStart[:2]))
+	length := int(binary.BigEndian.Uint16(dataStart[2:4]))
+	if len(dataStart) < length+4 {
+		return nil, fmt.Errorf("Invalid option length for vendor option %v. Declared %v, actual %v",
+			code, length, len(dataStart)-4,
+		)
+	}
+
+	optData := dataStart[4 : 4+length]
+	if len(optData) < 1 {
+		return nil, errors.New("vendParseOption: at least one vendor options data is required")
+	}
+
+	return &OptionGeneric{OptionCode: code, OptionData: optData}, nil
+}
diff --git a/dhcpv6/option_vendor_opts_test.go b/dhcpv6/option_vendor_opts_test.go
new file mode 100644
index 0000000..8e62506
--- /dev/null
+++ b/dhcpv6/option_vendor_opts_test.go
@@ -0,0 +1,101 @@
+package dhcpv6
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"testing"
+)
+
+func TestOptVendorOpts(t *testing.T) {
+	optData := []byte("Arista;DCS-7304;01.00;HSH14425148")
+	expected := []byte{0xaa, 0xbb, 0xcc, 0xdd}
+	expected = append(expected, []byte{0, 1, //code
+		0, byte(len(optData)), //length
+	}...)
+	expected = append(expected, optData...)
+	expectedOpts := OptVendorOpts{}
+	var vendorOpts []Option
+	expectedOpts.VendorOpts = append(vendorOpts, &OptionGeneric{OptionCode: 1, OptionData: optData})
+	opt, err := ParseOptVendorOpts(expected)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if optLen := opt.Length(); optLen != len(expected) {
+		t.Fatalf("Invalid length. Expected %v, got %v", len(expected), optLen)
+	}
+	if en := opt.EnterpriseNumber; en != 0xaabbccdd {
+		t.Fatalf("Invalid Enterprise Number. Expected 0xaabbccdd, got %v", en)
+	}
+	if !reflect.DeepEqual(opt.VendorOpts, expectedOpts.VendorOpts) {
+		t.Fatalf("Invalid Vendor Option Data. Expected %v, got %v", expected, expectedOpts.VendorOpts)
+	}
+
+	shortData := make([]byte, 1)
+	opt, err = ParseOptVendorOpts(shortData)
+	if err == nil {
+		t.Fatalf("Short data (<4 bytes) did not cause an error when it should have")
+	}
+
+}
+
+func TestOptVendorOptsToBytes(t *testing.T) {
+	optData := []byte("Arista;DCS-7304;01.00;HSH14425148")
+	var opts []Option
+	opts = append(opts, &OptionGeneric{OptionCode: 1, OptionData: optData})
+
+	var expected []byte
+	expected = append(expected, []byte{0, 17, // VendorOption Code 17
+		0, byte(len(optData) + 8), // Length of optionData + 4 (code & length of sub-option) + 4 for EnterpriseNumber Length
+		0, 0, 0, 0, // EnterpriseNumber
+		0, 1, // Sub-Option code from vendor
+		0, byte(len(optData))}...) // Length of optionData only
+	expected = append(expected, optData...)
+
+	opt := OptVendorOpts{
+		EnterpriseNumber: 0000,
+		VendorOpts:       opts,
+	}
+	toBytes := opt.ToBytes()
+	if !bytes.Equal(toBytes, expected) {
+		t.Fatalf("Invalid ToBytes result. Expected %v, got %v", expected, toBytes)
+	}
+}
+
+func TestVendParseOption(t *testing.T) {
+	var buf []byte
+	buf = append(buf, []byte{00, 1, 00, 33}...)
+	buf = append(buf, []byte("Arista;DCS-7304;01.00;HSH14425148")...)
+
+	expected := &OptionGeneric{OptionCode: 1, OptionData: []byte("Arista;DCS-7304;01.00;HSH14425148")}
+	opt, err := vendParseOption(buf)
+	if err != nil {
+		fmt.Println(err)
+	}
+	if !reflect.DeepEqual(opt, expected) {
+		t.Fatalf("Invalid Vendor Parse Option result. Expected %v, got %v", expected, opt)
+	}
+
+
+	shortData := make([]byte, 1) // data length too small
+	opt, err = vendParseOption(shortData)
+	if err == nil {
+		t.Fatalf("Short data (<4 bytes) did not cause an error when it should have")
+	}
+
+	shortData = []byte{0, 0, 0, 0} // missing actual vendor data.
+	opt, err = vendParseOption(shortData)
+	if err == nil {
+		t.Fatalf("Missing VendorData option. An error should have been returned but wasn't")
+	}
+
+	shortData = []byte{0, 0,
+		0, 4, // declared length
+		0} // data starts here, length of 1
+	opt, err = vendParseOption(shortData)
+	if err == nil {
+		t.Fatalf("Declared length does not match actual data length. An error should have been returned but wasn't")
+	}
+
+}
diff --git a/dhcpv6/options.go b/dhcpv6/options.go
index 5c4f321..8508b08 100644
--- a/dhcpv6/options.go
+++ b/dhcpv6/options.go
@@ -88,6 +88,8 @@ func ParseOption(dataStart []byte) (Option, error) {
 		opt, err = ParseOptUserClass(optData)
 	case OptionVendorClass:
 		opt, err = ParseOptVendorClass(optData)
+	case OptionVendorOpts:
+		opt, err = ParseOptVendorOpts(optData)
 	case OptionInterfaceID:
 		opt, err = ParseOptInterfaceId(optData)
 	case OptionDNSRecursiveNameServer:
@@ -120,6 +122,15 @@ func ParseOption(dataStart []byte) (Option, error) {
 }
 
 func OptionsFromBytes(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) {
 	// Parse a sequence of bytes until the end and build a list of options from
 	// it. Returns an error if any invalid option or length is found.
 	options := make([]Option, 0, 10)
@@ -140,7 +151,7 @@ func OptionsFromBytes(data []byte) ([]Option, error) {
 			// this should never happen
 			return nil, fmt.Errorf("Error: reading past the end of options")
 		}
-		opt, err := ParseOption(data[idx:])
+		opt, err := parser(data[idx:])
 		if err != nil {
 			return nil, err
 		}