3 files changed, 102 insertions, 0 deletions
diff --git a/dhcpv4/option_domain_search.go b/dhcpv4/option_domain_search.go
new file mode 100644
index 0000000..daade0a
--- /dev/null
+++ b/dhcpv4/option_domain_search.go
@@ -0,0 +1,63 @@
+package dhcpv4
+
+// This module defines the OptDomainSearch structure.
+// https://tools.ietf.org/html/rfc3397
+
+import (
+	"fmt"
+
+	"github.com/insomniacslk/dhcp/rfc1035label"
+)
+
+// OptDomainSearch represents an option encapsulating a domain search list.
+type OptDomainSearch struct {
+	DomainSearch []string
+}
+
+// Code returns the option code.
+func (op *OptDomainSearch) Code() OptionCode {
+	return OptionDNSDomainSearchList
+}
+
+// ToBytes returns a serialized stream of bytes for this option.
+func (op *OptDomainSearch) ToBytes() []byte {
+	buf := []byte{byte(op.Code()), byte(op.Length())}
+	buf = append(buf, rfc1035label.LabelsToBytes(op.DomainSearch)...)
+	return buf
+}
+
+// Length returns the length of the data portion (excluding option code an byte
+// length). 
+func (op *OptDomainSearch) Length() int {
+	var length int
+	for _, label := range op.DomainSearch {
+		length += len(label) + 2 // add the first and the last length bytes
+	}
+	return length
+}
+
+// String returns a human-readable string.
+func (op *OptDomainSearch) String() string {
+	return fmt.Sprintf("DNS Domain Search List -> %v", op.DomainSearch)
+}
+
+// ParseOptDomainSearch returns a new OptDomainSearch from a byte stream, or
+// error if any.
+func ParseOptDomainSearch(data []byte) (*OptDomainSearch, error) {
+	if len(data) < 2 {
+		return nil, ErrShortByteStream
+	}
+	code := OptionCode(data[0])
+	if code != OptionDNSDomainSearchList {
+		return nil, fmt.Errorf("expected code %v, got %v", OptionDNSDomainSearchList, code)
+	}
+	length := int(data[1])
+	if len(data) < 2+length {
+		return nil, ErrShortByteStream
+	}
+	domainSearch, err := rfc1035label.LabelsFromBytes(data[2:length+2])
+	if err != nil {
+		return nil, err
+	}
+	return &OptDomainSearch{DomainSearch: domainSearch}, nil
+}
diff --git a/dhcpv4/option_domain_search_test.go b/dhcpv4/option_domain_search_test.go
new file mode 100644
index 0000000..4848a83
--- /dev/null
+++ b/dhcpv4/option_domain_search_test.go
@@ -0,0 +1,37 @@
+package dhcpv4
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseOptDomainSearch(t *testing.T) {
+	data := []byte{
+		119, // OptionDNSDomainSearchList
+		33,  // length
+		7, 'e', 'x', 'a', 'm', 'p', 'l', 'e', 3, 'c', 'o', 'm', 0,
+		6, 's', 'u', 'b', 'n', 'e', 't', 7, 'e', 'x', 'a', 'm', 'p', 'l', 'e', 3, 'o', 'r', 'g', 0,
+	}
+	opt, err := ParseOptDomainSearch(data)
+	require.NoError(t, err)
+	require.Equal(t, len(opt.DomainSearch), 2)
+	require.Equal(t, opt.DomainSearch[0], "example.com")
+	require.Equal(t, opt.DomainSearch[1], "subnet.example.org")
+}
+
+func TestOptDomainSearchToBytes(t *testing.T) {
+	expected := []byte{
+		119, // OptionDNSDomainSearchList
+		33,  // length
+		7, 'e', 'x', 'a', 'm', 'p', 'l', 'e', 3, 'c', 'o', 'm', 0,
+		6, 's', 'u', 'b', 'n', 'e', 't', 7, 'e', 'x', 'a', 'm', 'p', 'l', 'e', 3, 'o', 'r', 'g', 0,
+	}
+	opt := OptDomainSearch{
+		DomainSearch: []string{
+			"example.com",
+			"subnet.example.org",
+		},
+	}
+	require.Equal(t, opt.ToBytes(), expected)
+}
diff --git a/dhcpv4/options.go b/dhcpv4/options.go
index 22e6eee..0be494f 100644
--- a/dhcpv4/options.go
+++ b/dhcpv4/options.go
@@ -76,6 +76,8 @@ func ParseOption(data []byte) (Option, error) {
 		opt, err = ParseOptBootfileName(data)
 	case OptionUserClassInformation:
 		opt, err = ParseOptUserClass(data)
+	case OptionDNSDomainSearchList:
+		opt, err = ParseOptDomainSearch(data)
 	default:
 		opt, err = ParseOptionGeneric(data)
 	}