package mpt import ( "fmt" "github.com/nspcc-dev/neo-go/pkg/crypto/hash" "github.com/nspcc-dev/neo-go/pkg/io" "github.com/nspcc-dev/neo-go/pkg/util" ) // MaxKeyLength is the max length of the extension node key. const MaxKeyLength = 1125 // ExtensionNode represents MPT's extension node. type ExtensionNode struct { hash util.Uint256 valid bool key []byte next Node } var _ Node = (*ExtensionNode)(nil) // NewExtensionNode returns hash node with the specified key and next node. // Note: because it is a part of Trie, key must be mangled, i.e. must contain only bytes with high half = 0. func NewExtensionNode(key []byte, next Node) *ExtensionNode { return &ExtensionNode{ key: key, next: next, } } // Type implements Node interface. func (e ExtensionNode) Type() NodeType { return ExtensionT } // Hash implements Node interface. func (e *ExtensionNode) Hash() util.Uint256 { if !e.valid { e.hash = hash.DoubleSha256(toBytes(e)) e.valid = true } return e.hash } // invalidateHash invalidates node hash. func (e *ExtensionNode) invalidateHash() { e.valid = false } // DecodeBinary implements io.Serializable. func (e *ExtensionNode) DecodeBinary(r *io.BinReader) { sz := r.ReadVarUint() if sz > MaxKeyLength { r.Err = fmt.Errorf("extension node key is too big: %d", sz) return } e.valid = false e.key = make([]byte, sz) r.ReadBytes(e.key) e.next = new(HashNode) e.next.DecodeBinary(r) } // EncodeBinary implements io.Serializable. func (e ExtensionNode) EncodeBinary(w *io.BinWriter) { w.WriteVarBytes(e.key) n := NewHashNode(e.next.Hash()) n.EncodeBinary(w) }