refactor: address namespace follow-ups from celestia-app v1.0.0-rc12 …

…bump (#2597)

Addresses two follow-ups from
#2581
Closes #2561

(cherry picked from commit 1205437)

share/namespace.go

@@ -14,13 +14,19 @@ const NamespaceSize = appns.NamespaceSize
 
 // Various reserved namespaces.
 var (
-	MaxReservedNamespace     = Namespace(appns.MaxReservedNamespace.Bytes())
-	ParitySharesNamespace    = Namespace(appns.ParitySharesNamespace.Bytes())
-	TailPaddingNamespace     = Namespace(appns.TailPaddingNamespace.Bytes())
-	ReservedPaddingNamespace = Namespace(appns.ReservedPaddingNamespace.Bytes())
-	TxNamespace              = Namespace(appns.TxNamespace.Bytes())
-	PayForBlobNamespace      = Namespace(appns.PayForBlobNamespace.Bytes())
-	ISRNamespace             = Namespace(appns.IntermediateStateRootsNamespace.Bytes())
+	// MaxPrimaryReservedNamespace is the highest primary reserved namespace.
+	// Namespaces lower than this are reserved for protocol use.
+	MaxPrimaryReservedNamespace = Namespace(appns.MaxPrimaryReservedNamespace.Bytes())
+	// MinSecondaryReservedNamespace is the lowest secondary reserved namespace
+	// reserved for protocol use. Namespaces higher than this are reserved for
+	// protocol use.
+	MinSecondaryReservedNamespace   = Namespace(appns.MinSecondaryReservedNamespace.Bytes())
+	ParitySharesNamespace           = Namespace(appns.ParitySharesNamespace.Bytes())
+	TailPaddingNamespace            = Namespace(appns.TailPaddingNamespace.Bytes())
+	PrimaryReservedPaddingNamespace = Namespace(appns.PrimaryReservedPaddingNamespace.Bytes())
+	TxNamespace                     = Namespace(appns.TxNamespace.Bytes())
+	PayForBlobNamespace             = Namespace(appns.PayForBlobNamespace.Bytes())
+	ISRNamespace                    = Namespace(appns.IntermediateStateRootsNamespace.Bytes())
 )
 
 // Namespace represents namespace of a Share.
@@ -124,7 +130,10 @@ func (n Namespace) ValidateForBlob() error {
 	if err := n.ValidateForData(); err != nil {
 		return err
 	}
-	if bytes.Compare(n, MaxReservedNamespace) < 1 {
+	if bytes.Compare(n, MaxPrimaryReservedNamespace) < 1 {
+		return fmt.Errorf("invalid blob namespace(%s): reserved namespaces are forbidden", n)
+	}
+	if bytes.Compare(n, MinSecondaryReservedNamespace) > -1 {
 		return fmt.Errorf("invalid blob namespace(%s): reserved namespaces are forbidden", n)
 	}
 	return nil

share/namespace_test.go

@@ -173,6 +173,16 @@ func TestValidateForBlob(t *testing.T) {
 			ns:      append([]byte{appns.NamespaceVersionMax}, bytes.Repeat([]byte{0x0}, appns.NamespaceIDSize)...),
 			wantErr: true,
 		},
+		{
+			name:    "invalid blob namespace: primary reserved namespace",
+			ns:      primaryReservedNamespace(0x10),
+			wantErr: true,
+		},
+		{
+			name:    "invalid blob namespace: secondary reserved namespace",
+			ns:      secondaryReservedNamespace(0x10),
+			wantErr: true,
+		},
 	}
 
 	for _, tc := range testCases {
@@ -186,5 +196,21 @@ func TestValidateForBlob(t *testing.T) {
 			assert.NoError(t, err)
 		})
 	}
+}
+
+func primaryReservedNamespace(lastByte byte) Namespace {
+	result := make([]byte, NamespaceSize)
+	result = append(result, appns.NamespaceVersionZero)
+	result = append(result, appns.NamespaceVersionZeroPrefix...)
+	result = append(result, bytes.Repeat([]byte{0x0}, appns.NamespaceVersionZeroIDSize-1)...)
+	result = append(result, lastByte)
+	return result
+}
 
+func secondaryReservedNamespace(lastByte byte) Namespace {
+	result := make([]byte, NamespaceSize)
+	result = append(result, appns.NamespaceVersionMax)
+	result = append(result, bytes.Repeat([]byte{0xFF}, appns.NamespaceIDSize-1)...)
+	result = append(result, lastByte)
+	return result
 }