Implemented RLP key field initialisation

This replaces the statically declared values, which previously replaced function varialbes see https://github.com/status-im/status-go/pull/1931#discussion_r406123786

waku/handshake.go

@@ -7,6 +7,7 @@ import (
 	"math"
 	"reflect"
 	"strconv"
+	"strings"
 
 	"github.com/ethereum/go-ethereum/rlp"
 )
@@ -25,27 +26,13 @@ type statusOptionKeyToType struct {
 
 const (
 	sOKTS statusOptionKeyType = iota + 1 // Status Option Key Type String
-	sOKTU                            // Status Option Key Type Uint
+	sOKTU                                // Status Option Key Type Uint
 )
 
 var (
 	defaultMinPoW = math.Float64bits(0.001)
-	idxFieldKey   = map[int]statusOptionKey{
-		0: 0,
-		1: 1,
-		2: 2,
-		3: 3,
-		4: 4,
-		5: 5,
-	}
-	keyFieldIdx = map[statusOptionKey]int{
-		0: 0,
-		1: 1,
-		2: 2,
-		3: 3,
-		4: 4,
-		5: 5,
-	}
+	idxFieldKey   = make(map[int]statusOptionKey)
+	keyFieldIdx   = make(map[statusOptionKey]int)
 )
 
 type keyTypeMapping struct {
@@ -69,6 +56,38 @@ type statusOptions struct {
 	keyTypeMapping       keyTypeMapping
 }
 
+// initFLPKeyFields initialises the values of `idxFieldKey` and `keyFieldIdx`
+func initRLPKeyFields() error {
+	o := statusOptions{}
+	v := reflect.ValueOf(o)
+
+	for i := 0; i < v.NumField(); i++ {
+		// skip unexported fields
+		if !v.Field(i).CanInterface() {
+			continue
+		}
+		rlpTag := v.Type().Field(i).Tag.Get("rlp")
+		// skip fields without rlp field tag
+		if rlpTag == "" {
+			continue
+		}
+
+		keys := strings.Split(rlpTag, "=")
+
+		// parse keys[1] as an int
+		key, err := strconv.ParseUint(keys[1], 10, 64)
+		if err != nil {
+			return fmt.Errorf("malformed rlp tag '%s', tag should be formatted 'rlp:\"key=0\"': %v", rlpTag, err)
+		}
+
+		// typecast key to be of statusOptionKey type
+		keyFieldIdx[statusOptionKey(key)] = i
+		idxFieldKey[i] = statusOptionKey(key)
+	}
+
+	return nil
+}
+
 // WithDefaults adds the default values for a given peer.
 // This are not the host default values, but the default values that ought to
 // be used when receiving from an update from a peer.

waku/handshake_test.go

@@ -2,9 +2,6 @@ package waku
 
 import (
 	"math"
-	"reflect"
-	"strconv"
-	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -67,60 +64,47 @@ func TestForwardCompatibility(t *testing.T) {
 	require.EqualValues(t, statusOptions{PoWRequirement: &pow}, optsDecoded)
 }
 
-func TestStatusOptionKeys(t *testing.T) {
-	o := statusOptions{}
-
-	kfi := make(map[statusOptionKey]int)
-	ifk := make(map[int]statusOptionKey)
-
-	v := reflect.ValueOf(o)
-
-	for i := 0; i < v.NumField(); i++ {
-		// skip unexported fields
-		if !v.Field(i).CanInterface() {
-			continue
-		}
-		rlpTag := v.Type().Field(i).Tag.Get("rlp")
-		// skip fields without rlp field tag
-		if rlpTag == "" {
-			continue
-		}
-
-		keys := strings.Split(rlpTag, "=")
-		require.Equal(t, 2, len(keys))
-
-		// parse keys[1] as an int
-		key, err := strconv.ParseUint(keys[1], 10, 64)
-		require.NoError(t, err)
-
-		// typecast key to be of statusOptionKey type
-		kfi[statusOptionKey(key)] = i
-		ifk[i] = statusOptionKey(key)
+func TestInitRLPKeyFields(t *testing.T) {
+	ifk := map[int]statusOptionKey{
+		0: 0,
+		1: 1,
+		2: 2,
+		3: 3,
+		4: 4,
+		5: 5,
+	}
+	kfi := map[statusOptionKey]int{
+		0: 0,
+		1: 1,
+		2: 2,
+		3: 3,
+		4: 4,
+		5: 5,
 	}
 
-	// Test that the statusOptions' derived kfi length matches the global keyFieldIdx length
-	require.Equal(t, len(keyFieldIdx), len(kfi))
+	// Test that the kfi length matches the inited global keyFieldIdx length
+	require.Equal(t, len(kfi), len(keyFieldIdx))
 
-	// Test that each index of the statusOptions' derived kfi values matches the global keyFieldIdx of the same index
+	// Test that each index of the kfi values matches the inited global keyFieldIdx of the same index
 	for k, v := range kfi {
-		require.Exactly(t, keyFieldIdx[k], v)
+		require.Exactly(t, v, keyFieldIdx[k])
 	}
 
-	// Test that each index of the global keyFieldIdx values matches statusOptions' derived kfi values of the same index
+	// Test that each index of the inited global keyFieldIdx values matches kfi values of the same index
 	for k, v := range keyFieldIdx {
-		require.Exactly(t, kfi[k], v)
+		require.Exactly(t, v, kfi[k])
 	}
 
-	// Test that the statusOptions' derived ifk length matches the global idxFieldKey length
-	require.Equal(t, len(idxFieldKey), len(ifk))
+	// Test that the ifk length matches the inited global idxFieldKey length
+	require.Equal(t, len(ifk), len(idxFieldKey))
 
-	// Test that each index of the statusOptions' derived ifk values matches the global idxFieldKey of the same index
+	// Test that each index of the ifk values matches the inited global idxFieldKey of the same index
 	for k, v := range ifk {
-		require.Exactly(t, idxFieldKey[k], v)
+		require.Exactly(t, v, idxFieldKey[k])
 	}
 
-	// Test that each index of the global idxFieldKey values matches statusOptions' derived ifk values of the same index
+	// Test that each index of the inited global idxFieldKey values matches ifk values of the same index
 	for k, v := range idxFieldKey {
-		require.Exactly(t, ifk[k], v)
+		require.Exactly(t, v, ifk[k])
 	}
 }

waku/waku.go

@@ -108,6 +108,14 @@ type Waku struct {
 	logger *zap.Logger
 }
 
+// init initialises the waku package
+func init() {
+	err := initRLPKeyFields()
+	if err != nil {
+		panic(err)
+	}
+}
+
 // New creates a Waku client ready to communicate through the Ethereum P2P network.
 func New(cfg *Config, logger *zap.Logger) *Waku {
 	if cfg == nil {