package block import ( "encoding/json" "errors" "fmt" "github.com/nspcc-dev/neo-go/pkg/core/transaction" "github.com/nspcc-dev/neo-go/pkg/crypto/hash" "github.com/nspcc-dev/neo-go/pkg/encoding/address" "github.com/nspcc-dev/neo-go/pkg/io" "github.com/nspcc-dev/neo-go/pkg/util" ) // Base holds the base info of a block type Base struct { // Version of the block. Version uint32 // hash of the previous block. PrevHash util.Uint256 // Root hash of a transaction list. MerkleRoot util.Uint256 // Timestamp is a millisecond-precision timestamp. // The time stamp of each block must be later than previous block's time stamp. // Generally the difference of two block's time stamp is about 15 seconds and imprecision is allowed. // The height of the block must be exactly equal to the height of the previous block plus 1. Timestamp uint64 // index/height of the block Index uint32 // Contract address of the next miner NextConsensus util.Uint160 // Padding that is fixed to 1 _ uint8 // Script used to validate the block Script transaction.Witness // Hash of this block, created when binary encoded (double SHA256). hash util.Uint256 // Hash of the block used to verify it (single SHA256). verificationHash util.Uint256 } // baseAux is used to marshal/unmarshal to/from JSON, it's almost the same // as original Base, but with Nonce and NextConsensus fields differing and // Hash added. type baseAux struct { Hash util.Uint256 `json:"hash"` Version uint32 `json:"version"` PrevHash util.Uint256 `json:"previousblockhash"` MerkleRoot util.Uint256 `json:"merkleroot"` Timestamp uint64 `json:"time"` Index uint32 `json:"index"` NextConsensus string `json:"nextconsensus"` Witnesses []transaction.Witness `json:"witnesses"` } // Verify verifies the integrity of the Base. func (b *Base) Verify() bool { // TODO: Need a persisted blockchain for this. return true } // Hash returns the hash of the block. func (b *Base) Hash() util.Uint256 { if b.hash.Equals(util.Uint256{}) { b.createHash() } return b.hash } // VerificationHash returns the hash of the block used to verify it. func (b *Base) VerificationHash() util.Uint256 { if b.verificationHash.Equals(util.Uint256{}) { b.createHash() } return b.verificationHash } // DecodeBinary implements Serializable interface. func (b *Base) DecodeBinary(br *io.BinReader) { b.decodeHashableFields(br) padding := []byte{0} br.ReadBytes(padding) if padding[0] != 1 { br.Err = fmt.Errorf("format error: padding must equal 1 got %d", padding) return } b.Script.DecodeBinary(br) } // EncodeBinary implements Serializable interface func (b *Base) EncodeBinary(bw *io.BinWriter) { b.encodeHashableFields(bw) bw.WriteBytes([]byte{1}) b.Script.EncodeBinary(bw) } // GetSignedPart returns serialized hashable data of the block. func (b *Base) GetSignedPart() []byte { buf := io.NewBufBinWriter() // No error can occure while encoding hashable fields. b.encodeHashableFields(buf.BinWriter) return buf.Bytes() } // createHash creates the hash of the block. // When calculating the hash value of the block, instead of calculating the entire block, // only first seven fields in the block head will be calculated, which are // version, PrevBlock, MerkleRoot, timestamp, and height, the nonce, NextMiner. // Since MerkleRoot already contains the hash value of all transactions, // the modification of transaction will influence the hash value of the block. func (b *Base) createHash() { bb := b.GetSignedPart() b.verificationHash = hash.Sha256(bb) b.hash = hash.Sha256(b.verificationHash.BytesBE()) } // encodeHashableFields will only encode the fields used for hashing. // see Hash() for more information about the fields. func (b *Base) encodeHashableFields(bw *io.BinWriter) { bw.WriteU32LE(b.Version) bw.WriteBytes(b.PrevHash[:]) bw.WriteBytes(b.MerkleRoot[:]) bw.WriteU64LE(b.Timestamp) bw.WriteU32LE(b.Index) bw.WriteBytes(b.NextConsensus[:]) } // decodeHashableFields decodes the fields used for hashing. // see Hash() for more information about the fields. func (b *Base) decodeHashableFields(br *io.BinReader) { b.Version = br.ReadU32LE() br.ReadBytes(b.PrevHash[:]) br.ReadBytes(b.MerkleRoot[:]) b.Timestamp = br.ReadU64LE() b.Index = br.ReadU32LE() br.ReadBytes(b.NextConsensus[:]) // Make the hash of the block here so we dont need to do this // again. if br.Err == nil { b.createHash() } } // MarshalJSON implements json.Marshaler interface. func (b Base) MarshalJSON() ([]byte, error) { aux := baseAux{ Hash: b.Hash(), Version: b.Version, PrevHash: b.PrevHash, MerkleRoot: b.MerkleRoot, Timestamp: b.Timestamp, Index: b.Index, NextConsensus: address.Uint160ToString(b.NextConsensus), Witnesses: []transaction.Witness{b.Script}, } return json.Marshal(aux) } // UnmarshalJSON implements json.Unmarshaler interface. func (b *Base) UnmarshalJSON(data []byte) error { var aux = new(baseAux) var nextC util.Uint160 err := json.Unmarshal(data, aux) if err != nil { return err } nextC, err = address.StringToUint160(aux.NextConsensus) if err != nil { return err } if len(aux.Witnesses) != 1 { return errors.New("wrong number of witnesses") } b.Version = aux.Version b.PrevHash = aux.PrevHash b.MerkleRoot = aux.MerkleRoot b.Timestamp = aux.Timestamp b.Index = aux.Index b.NextConsensus = nextC b.Script = aux.Witnesses[0] if !aux.Hash.Equals(b.Hash()) { return errors.New("json 'hash' doesn't match block hash") } return nil }