Documentation
¶
Overview ¶
Package vm implements the VM described in Chain Protocol 1.
The VM is for verifying transaction inputs and blocks. Accordingly there are two main entrypoints: VerifyTxInput and VerifyBlockHeader, both in vm.go. Each constructs a disposable VM object to perform its computation.
For VerifyTxInput, the program to execute comes from the input commitment: either the prevout's control program, if it's a spend input; or the issuance program, if it's an issuance. For VerifyBlockHeader, the program to execute is the previous block's consensus program. In all cases, the VM's data stack is first populated with witness data from the current object (transaction input or block).
The program is interpreted byte-by-byte by the main loop in virtualMachine.run(). Most bytes are opcodes in one of the following categories:
- bitwise
- control
- crypto
- introspection
- numeric
- pushdata
- splice
- stack
Each category has a corresponding .go file implementing those opcodes.
Each instruction incurs some cost when executed. These costs are deducted from (and in some cases refunded to) a predefined run limit. Costs are tallied in two conceptual phases: "before" the instruction runs and "after." In practice, "before" charges are applied on the fly in the body of each opcode's implementation, and "after" charges are deferred until the instruction finishes, at which point the VM main loop applies the deferred charges. As such, functions that have associated costs (chiefly stack pushing and popping) include a "deferred" flag as an argument.
Index ¶
- Variables
- func AsBool(bytes []byte) bool
- func AsInt64(b []byte) (int64, error)
- func Assemble(s string) (res []byte, err error)
- func BoolBytes(b bool) (result []byte)
- func Disassemble(prog []byte) (string, error)
- func Int64Bytes(n int64) []byte
- func PushdataBytes(in []byte) []byte
- func PushdataInt64(n int64) []byte
- func VerifyBlockHeader(prev *bc.BlockHeader, block *bc.Block) (ok bool, err error)
- func VerifyTxInput(tx *bc.Tx, inputIndex int) (ok bool, err error)
- type Instruction
- type Op
Constants ¶
This section is empty.
Variables ¶
var ( ErrAltStackUnderflow = errors.New("alt stack underflow") ErrBadValue = errors.New("bad value") ErrContext = errors.New("wrong context") ErrDataStackUnderflow = errors.New("data stack underflow") ErrDisallowedOpcode = errors.New("disallowed opcode") ErrDivZero = errors.New("division by zero") ErrLongProgram = errors.New("program size exceeds maxint32") ErrRange = errors.New("range error") ErrReturn = errors.New("RETURN executed") ErrRunLimitExceeded = errors.New("run limit exceeded") ErrShortProgram = errors.New("unexpected end of program") ErrToken = errors.New("unrecognized token") ErrUnexpected = errors.New("unexpected error") ErrUnsupportedTx = errors.New("unsupported transaction type") ErrUnsupportedVM = errors.New("unsupported VM") ErrVerifyFailed = errors.New("VERIFY failed") )
var TraceOut io.Writer
TraceOut - if non-nil - will receive trace output during execution.
Functions ¶
func Assemble ¶
Assemble converts a string like "2 3 ADD 5 NUMEQUAL" into 0x525393559c. The input should not include PUSHDATA (or OP_<num>) ops; those will be inferred. Input may include jump-target labels of the form $foo, which can then be used as JUMP:$foo or JUMPIF:$foo.
func Disassemble ¶
func Int64Bytes ¶
func PushdataBytes ¶
func PushdataInt64 ¶
func VerifyBlockHeader ¶
Types ¶
type Instruction ¶
func ParseOp ¶
func ParseOp(prog []byte, pc uint32) (inst Instruction, err error)
ParseOp parses the op at position pc in prog, returning the parsed instruction (opcode plus any associated data).
func ParseProgram ¶
func ParseProgram(prog []byte) ([]Instruction, error)
type Op ¶
type Op uint8
const ( OP_FALSE Op = 0x00 OP_0 Op = 0x00 // synonym OP_1 Op = 0x51 OP_TRUE Op = 0x51 // synonym OP_2 Op = 0x52 OP_3 Op = 0x53 OP_4 Op = 0x54 OP_5 Op = 0x55 OP_6 Op = 0x56 OP_7 Op = 0x57 OP_8 Op = 0x58 OP_9 Op = 0x59 OP_10 Op = 0x5a OP_11 Op = 0x5b OP_12 Op = 0x5c OP_13 Op = 0x5d OP_14 Op = 0x5e OP_15 Op = 0x5f OP_16 Op = 0x60 OP_DATA_1 Op = 0x01 OP_DATA_2 Op = 0x02 OP_DATA_3 Op = 0x03 OP_DATA_4 Op = 0x04 OP_DATA_5 Op = 0x05 OP_DATA_6 Op = 0x06 OP_DATA_7 Op = 0x07 OP_DATA_8 Op = 0x08 OP_DATA_9 Op = 0x09 OP_DATA_10 Op = 0x0a OP_DATA_11 Op = 0x0b OP_DATA_12 Op = 0x0c OP_DATA_13 Op = 0x0d OP_DATA_14 Op = 0x0e OP_DATA_15 Op = 0x0f OP_DATA_16 Op = 0x10 OP_DATA_17 Op = 0x11 OP_DATA_18 Op = 0x12 OP_DATA_19 Op = 0x13 OP_DATA_20 Op = 0x14 OP_DATA_21 Op = 0x15 OP_DATA_22 Op = 0x16 OP_DATA_23 Op = 0x17 OP_DATA_24 Op = 0x18 OP_DATA_25 Op = 0x19 OP_DATA_26 Op = 0x1a OP_DATA_27 Op = 0x1b OP_DATA_28 Op = 0x1c OP_DATA_29 Op = 0x1d OP_DATA_30 Op = 0x1e OP_DATA_31 Op = 0x1f OP_DATA_32 Op = 0x20 OP_DATA_33 Op = 0x21 OP_DATA_34 Op = 0x22 OP_DATA_35 Op = 0x23 OP_DATA_36 Op = 0x24 OP_DATA_37 Op = 0x25 OP_DATA_38 Op = 0x26 OP_DATA_39 Op = 0x27 OP_DATA_40 Op = 0x28 OP_DATA_41 Op = 0x29 OP_DATA_42 Op = 0x2a OP_DATA_43 Op = 0x2b OP_DATA_44 Op = 0x2c OP_DATA_45 Op = 0x2d OP_DATA_46 Op = 0x2e OP_DATA_47 Op = 0x2f OP_DATA_48 Op = 0x30 OP_DATA_49 Op = 0x31 OP_DATA_50 Op = 0x32 OP_DATA_51 Op = 0x33 OP_DATA_52 Op = 0x34 OP_DATA_53 Op = 0x35 OP_DATA_54 Op = 0x36 OP_DATA_55 Op = 0x37 OP_DATA_56 Op = 0x38 OP_DATA_57 Op = 0x39 OP_DATA_58 Op = 0x3a OP_DATA_59 Op = 0x3b OP_DATA_60 Op = 0x3c OP_DATA_61 Op = 0x3d OP_DATA_62 Op = 0x3e OP_DATA_63 Op = 0x3f OP_DATA_64 Op = 0x40 OP_DATA_65 Op = 0x41 OP_DATA_66 Op = 0x42 OP_DATA_67 Op = 0x43 OP_DATA_68 Op = 0x44 OP_DATA_69 Op = 0x45 OP_DATA_70 Op = 0x46 OP_DATA_71 Op = 0x47 OP_DATA_72 Op = 0x48 OP_DATA_73 Op = 0x49 OP_DATA_74 Op = 0x4a OP_DATA_75 Op = 0x4b OP_PUSHDATA1 Op = 0x4c OP_PUSHDATA2 Op = 0x4d OP_PUSHDATA4 Op = 0x4e OP_1NEGATE Op = 0x4f OP_NOP Op = 0x61 OP_JUMP Op = 0x63 OP_JUMPIF Op = 0x64 OP_VERIFY Op = 0x69 OP_FAIL Op = 0x6a OP_CHECKPREDICATE Op = 0xc0 OP_TOALTSTACK Op = 0x6b OP_FROMALTSTACK Op = 0x6c OP_2DROP Op = 0x6d OP_2DUP Op = 0x6e OP_3DUP Op = 0x6f OP_2OVER Op = 0x70 OP_2ROT Op = 0x71 OP_2SWAP Op = 0x72 OP_IFDUP Op = 0x73 OP_DEPTH Op = 0x74 OP_DROP Op = 0x75 OP_DUP Op = 0x76 OP_NIP Op = 0x77 OP_OVER Op = 0x78 OP_PICK Op = 0x79 OP_ROLL Op = 0x7a OP_ROT Op = 0x7b OP_SWAP Op = 0x7c OP_TUCK Op = 0x7d OP_CAT Op = 0x7e OP_SUBSTR Op = 0x7f OP_LEFT Op = 0x80 OP_RIGHT Op = 0x81 OP_SIZE Op = 0x82 OP_CATPUSHDATA Op = 0x89 OP_INVERT Op = 0x83 OP_AND Op = 0x84 OP_OR Op = 0x85 OP_XOR Op = 0x86 OP_EQUAL Op = 0x87 OP_EQUALVERIFY Op = 0x88 OP_1ADD Op = 0x8b OP_1SUB Op = 0x8c OP_2MUL Op = 0x8d OP_2DIV Op = 0x8e OP_NEGATE Op = 0x8f OP_ABS Op = 0x90 OP_NOT Op = 0x91 OP_0NOTEQUAL Op = 0x92 OP_ADD Op = 0x93 OP_SUB Op = 0x94 OP_MUL Op = 0x95 OP_DIV Op = 0x96 OP_MOD Op = 0x97 OP_LSHIFT Op = 0x98 OP_RSHIFT Op = 0x99 OP_BOOLAND Op = 0x9a OP_BOOLOR Op = 0x9b OP_NUMEQUAL Op = 0x9c OP_NUMEQUALVERIFY Op = 0x9d OP_NUMNOTEQUAL Op = 0x9e OP_LESSTHAN Op = 0x9f OP_GREATERTHAN Op = 0xa0 OP_LESSTHANOREQUAL Op = 0xa1 OP_GREATERTHANOREQUAL Op = 0xa2 OP_MIN Op = 0xa3 OP_MAX Op = 0xa4 OP_WITHIN Op = 0xa5 OP_RIPEMD160 Op = 0xa6 OP_SHA1 Op = 0xa7 OP_SHA256 Op = 0xa8 OP_SHA3 Op = 0xaa OP_CHECKSIG Op = 0xac OP_CHECKMULTISIG Op = 0xad OP_TXSIGHASH Op = 0xae OP_BLOCKSIGHASH Op = 0xaf OP_CHECKOUTPUT Op = 0xc1 OP_ASSET Op = 0xc2 OP_AMOUNT Op = 0xc3 OP_PROGRAM Op = 0xc4 OP_MINTIME Op = 0xc5 OP_MAXTIME Op = 0xc6 OP_TXREFDATAHASH Op = 0xc7 OP_REFDATAHASH Op = 0xc8 OP_INDEX Op = 0xc9 OP_OUTPOINT Op = 0xcb OP_NONCE Op = 0xcc OP_NEXTPROGRAM Op = 0xcd OP_BLOCKTIME Op = 0xce )
Source Files