Attempt at "failing gracefully" for dhcpv6

dhcpv6/option_generic_parse_failure.go

@@ -0,0 +1,27 @@
+package dhcpv6
+
+import (
+	"fmt"
+)
+
+// OptionGenericParseFailure represents an option that failed to be parsed correctly
+type OptionGenericParseFailure struct {
+	OptionCode OptionCode
+	OptionData []byte
+	Option     Option
+	Error      error
+}
+
+// Code returns the option's code
+func (og *OptionGenericParseFailure) Code() OptionCode {
+	return og.OptionCode
+}
+
+// ToBytes serializes the option and returns it as a sequence of bytes
+func (og *OptionGenericParseFailure) ToBytes() []byte {
+	return og.OptionData
+}
+
+func (og *OptionGenericParseFailure) String() string {
+	return fmt.Sprintf("GenericParseFailure(%v): %v, Error=%v", og.OptionCode, og.Option, og.Error)
+}

dhcpv6/option_generic_parse_failure_test.go

@@ -0,0 +1,37 @@
+package dhcpv6
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestOptGenericParseFailure(t *testing.T) {
+	buf := []byte{
+		0xaa, 0xbb, 0xcc, 0xdd, // EnterpriseNumber
+		12, 0, // length is little-endian - should be big-endian
+		'd', 's', 'l', 'f', 'o', 'r', 'u', 'm', '.', 'o', 'r', 'g',
+	}
+	opt, _ := ParseOption(OptionVendorClass, buf)
+	require.IsType(t, &OptionGenericParseFailure{}, opt)
+	failedOpt, ok := opt.(*OptionGenericParseFailure)
+	require.True(t, ok)
+	require.Contains(
+		t,
+		failedOpt.Error.Error(),
+		"buffer too short",
+		"Error() should return the original parser error",
+	)
+	require.Contains(
+		t,
+		failedOpt.String(),
+		"GenericParseFailure(Vendor Class)",
+		"String() should include the Option Code",
+	)
+	require.Contains(
+		t,
+		failedOpt.String(),
+		"enterprisenum=2864434397",
+		"String() should include the details of the failed option",
+	)
+}

dhcpv6/options.go

@@ -107,9 +107,9 @@ func ParseOption(code OptionCode, optData []byte) (Option, error) {
 		opt = &OptionGeneric{OptionCode: code, OptionData: optData}
 	}
 	if err != nil {
-		return nil, err
+		opt = &OptionGenericParseFailure{OptionCode: code, OptionData: optData, Option: opt, Error: err}
 	}
-	return opt, nil
+	return opt, err
 }
 
 // Options is a collection of options.
@@ -205,10 +205,7 @@ func (o *Options) FromBytesWithParser(data []byte, parser OptionParser) error {
 		// pertinent data.
 		optData := buf.Consume(length)
 
-		opt, err := parser(code, optData)
-		if err != nil {
-			return err
-		}
+		opt, _ := parser(code, optData)
 		*o = append(*o, opt)
 	}
 	return buf.FinError()