// Copyright (c) 2013-2017 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package txscript
import (
"fmt"
)
// ErrorCode identifies a kind of script error.
type ErrorCode int
// These constants are used to identify a specific Error.
const (
// ErrInternal is returned if internal consistency checks fail. In
// practice this error should never be seen as it would mean there is an
// error in the engine logic.
ErrInternal ErrorCode = iota
// ---------------------------------------
// Failures related to improper API usage.
// ---------------------------------------
// ErrInvalidFlags is returned when the passed flags to NewEngine
// contain an invalid combination.
ErrInvalidFlags
// ErrInvalidIndex is returned when an out-of-bounds index is passed to
// a function.
ErrInvalidIndex
// ErrUnsupportedAddress is returned when a concrete type that
// implements a btcutil.Address is not a supported type.
ErrUnsupportedAddress
// ErrNotMultisigScript is returned from CalcMultiSigStats when the
// provided script is not a multisig script.
ErrNotMultisigScript
// ErrTooManyRequiredSigs is returned from MultiSigScript when the
// specified number of required signatures is larger than the number of
// provided public keys.
ErrTooManyRequiredSigs
// ErrTooMuchNullData is returned from NullDataScript when the length of
// the provided data exceeds MaxDataCarrierSize.
ErrTooMuchNullData
// ------------------------------------------
// Failures related to final execution state.
// ------------------------------------------
// ErrEarlyReturn is returned when OP_RETURN is executed in the script.
ErrEarlyReturn
// ErrEmptyStack is returned when the script evaluated without error,
// but terminated with an empty top stack element.
ErrEmptyStack
// ErrEvalFalse is returned when the script evaluated without error but
// terminated with a false top stack element.
ErrEvalFalse
// ErrScriptUnfinished is returned when CheckErrorCondition is called on
// a script that has not finished executing.
ErrScriptUnfinished
// ErrScriptDone is returned when an attempt to execute an opcode is
// made once all of them have already been executed. This can happen
// due to things such as a second call to Execute or calling Step after
// all opcodes have already been executed.
ErrInvalidProgramCounter
// -----------------------------------------------------
// Failures related to exceeding maximum allowed limits.
// -----------------------------------------------------
// ErrScriptTooBig is returned if a script is larger than MaxScriptSize.
ErrScriptTooBig
// ErrElementTooBig is returned if the size of an element to be pushed
// to the stack is over MaxScriptElementSize.
ErrElementTooBig
// ErrTooManyOperations is returned if a script has more than
// MaxOpsPerScript opcodes that do not push data.
ErrTooManyOperations
// ErrStackOverflow is returned when stack and altstack combined depth
// is over the limit.
ErrStackOverflow
// ErrInvalidPubKeyCount is returned when the number of public keys
// specified for a multsig is either negative or greater than
// MaxPubKeysPerMultiSig.
ErrInvalidPubKeyCount
// ErrInvalidSignatureCount is returned when the number of signatures
// specified for a multisig is either negative or greater than the
// number of public keys.
ErrInvalidSignatureCount
// ErrNumberTooBig is returned when the argument for an opcode that
// expects numeric input is larger than the expected maximum number of
// bytes. For the most part, opcodes that deal with stack manipulation
// via offsets, arithmetic, numeric comparison, and boolean logic are
// those that this applies to. However, any opcode that expects numeric
// input may fail with this code.
ErrNumberTooBig
// --------------------------------------------
// Failures related to verification operations.
// --------------------------------------------
// ErrVerify is returned when OP_VERIFY is encountered in a script and
// the top item on the data stack does not evaluate to true.
ErrVerify
// ErrEqualVerify is returned when OP_EQUALVERIFY is encountered in a
// script and the top item on the data stack does not evaluate to true.
ErrEqualVerify
// ErrNumEqualVerify is returned when OP_NUMEQUALVERIFY is encountered
// in a script and the top item on the data stack does not evaluate to
// true.
ErrNumEqualVerify
// ErrCheckSigVerify is returned when OP_CHECKSIGVERIFY is encountered
// in a script and the top item on the data stack does not evaluate to
// true.
ErrCheckSigVerify
// ErrCheckSigVerify is returned when OP_CHECKMULTISIGVERIFY is
// encountered in a script and the top item on the data stack does not
// evaluate to true.
ErrCheckMultiSigVerify
// --------------------------------------------
// Failures related to improper use of opcodes.
// --------------------------------------------
// ErrDisabledOpcode is returned when a disabled opcode is encountered
// in a script.
ErrDisabledOpcode
// ErrReservedOpcode is returned when an opcode marked as reserved
// is encountered in a script.
ErrReservedOpcode
// ErrMalformedPush is returned when a data push opcode tries to push
// more bytes than are left in the script.
ErrMalformedPush
// ErrInvalidStackOperation is returned when a stack operation is
// attempted with a number that is invalid for the current stack size.
ErrInvalidStackOperation
// ErrUnbalancedConditional is returned when an OP_ELSE or OP_ENDIF is
// encountered in a script without first having an OP_IF or OP_NOTIF or
// the end of script is reached without encountering an OP_ENDIF when
// an OP_IF or OP_NOTIF was previously encountered.
ErrUnbalancedConditional
// ---------------------------------
// Failures related to malleability.
// ---------------------------------
// ErrMinimalData is returned when the ScriptVerifyMinimalData flag
// is set and the script contains push operations that do not use
// the minimal opcode required.
ErrMinimalData
// ErrInvalidSigHashType is returned when a signature hash type is not
// one of the supported types.
ErrInvalidSigHashType
// ErrSigDER is returned when a signature is not a canonically-encoded
// DER signature.
ErrSigDER
// ErrSigHighS is returned when the ScriptVerifyLowS flag is set and the
// script contains any signatures whose S values are higher than the
// half order.
ErrSigHighS
// ErrNotPushOnly is returned when a script that is required to only
// push data to the stack performs other operations. A couple of cases
// where this applies is for a pay-to-script-hash signature script when
// bip16 is active and when the ScriptVerifySigPushOnly flag is set.
ErrNotPushOnly
// ErrSigNullDummy is returned when the ScriptStrictMultiSig flag is set
// and a multisig script has anything other than 0 for the extra dummy
// argument.
ErrSigNullDummy
// ErrPubKeyType is returned when the ScriptVerifyStrictEncoding
// flag is set and the script contains invalid public keys.
ErrPubKeyType
// ErrCleanStack is returned when the ScriptVerifyCleanStack flag
// is set, and after evalution, the stack does not contain only a
// single element.
ErrCleanStack
// ErrNullFail is returned when the ScriptVerifyNullFail flag is
// set and signatures are not empty on failed checksig or checkmultisig
// operations.
ErrNullFail
// ErrWitnessMalleated is returned if ScriptVerifyWitness is set and a
// native p2wsh program is encountered which has a non-empty sigScript.
ErrWitnessMalleated
// ErrWitnessMalleatedP2SH is returned if ScriptVerifyWitness if set
// and the validation logic for nested p2sh encounters a sigScript
// which isn't *exactyl* a datapush of the witness program.
ErrWitnessMalleatedP2SH
// -------------------------------
// Failures related to soft forks.
// -------------------------------
// ErrDiscourageUpgradableNOPs is returned when the
// ScriptDiscourageUpgradableNops flag is set and a NOP opcode is
// encountered in a script.
ErrDiscourageUpgradableNOPs
// ErrNegativeLockTime is returned when a script contains an opcode that
// interprets a negative lock time.
ErrNegativeLockTime
// ErrUnsatisfiedLockTime is returned when a script contains an opcode
// that involves a lock time and the required lock time has not been
// reached.
ErrUnsatisfiedLockTime
// ErrMinimalIf is returned if ScriptVerifyWitness is set and the
// operand of an OP_IF/OP_NOF_IF are not either an empty vector or
// [0x01].
ErrMinimalIf
// ErrDiscourageUpgradableWitnessProgram is returned if
// ScriptVerifyWitness is set and the versino of an executing witness
// program is outside the set of currently defined witness program
// vesions.
ErrDiscourageUpgradableWitnessProgram
// ----------------------------------------
// Failures related to segregated witness.
// ----------------------------------------
// ErrWitnessProgramEmpty is returned if ScriptVerifyWitness is set and
// the witness stack itself is empty.
ErrWitnessProgramEmpty
// ErrWitnessProgramMismatch is returned if ScriptVerifyWitness is set
// and the witness itself for a p2wkh witness program isn't *exactly* 2
// items or if the witness for a p2wsh isn't the sha255 of the witness
// script.
ErrWitnessProgramMismatch
// ErrWitnessProgramWrongLength is returned if ScriptVerifyWitness is
// set and the length of the witness program violates the length as
// dictated by the current witness version.
ErrWitnessProgramWrongLength
// ErrWitnessUnexpected is returned if ScriptVerifyWitness is set and a
// transaction includes witness data but doesn't spend an which is a
// witness program (nested or native).
ErrWitnessUnexpected
// ErrWitnessPubKeyType is returned if ScriptVerifyWitness is set and
// the public key used in either a check-sig or check-multi-sig isn't
// serialized in a compressed format.
ErrWitnessPubKeyType
// numErrorCodes is the maximum error code number used in tests. This
// entry MUST be the last entry in the enum.
numErrorCodes
)
// Map of ErrorCode values back to their constant names for pretty printing.
var errorCodeStrings = map[ErrorCode]string{
ErrInternal: "ErrInternal",
ErrInvalidFlags: "ErrInvalidFlags",
ErrInvalidIndex: "ErrInvalidIndex",
ErrUnsupportedAddress: "ErrUnsupportedAddress",
ErrNotMultisigScript: "ErrNotMultisigScript",
ErrTooManyRequiredSigs: "ErrTooManyRequiredSigs",
ErrTooMuchNullData: "ErrTooMuchNullData",
ErrEarlyReturn: "ErrEarlyReturn",
ErrEmptyStack: "ErrEmptyStack",
ErrEvalFalse: "ErrEvalFalse",
ErrScriptUnfinished: "ErrScriptUnfinished",
ErrInvalidProgramCounter: "ErrInvalidProgramCounter",
ErrScriptTooBig: "ErrScriptTooBig",
ErrElementTooBig: "ErrElementTooBig",
ErrTooManyOperations: "ErrTooManyOperations",
ErrStackOverflow: "ErrStackOverflow",
ErrInvalidPubKeyCount: "ErrInvalidPubKeyCount",
ErrInvalidSignatureCount: "ErrInvalidSignatureCount",
ErrNumberTooBig: "ErrNumberTooBig",
ErrVerify: "ErrVerify",
ErrEqualVerify: "ErrEqualVerify",
ErrNumEqualVerify: "ErrNumEqualVerify",
ErrCheckSigVerify: "ErrCheckSigVerify",
ErrCheckMultiSigVerify: "ErrCheckMultiSigVerify",
ErrDisabledOpcode: "ErrDisabledOpcode",
ErrReservedOpcode: "ErrReservedOpcode",
ErrMalformedPush: "ErrMalformedPush",
ErrInvalidStackOperation: "ErrInvalidStackOperation",
ErrUnbalancedConditional: "ErrUnbalancedConditional",
ErrMinimalData: "ErrMinimalData",
ErrInvalidSigHashType: "ErrInvalidSigHashType",
ErrSigDER: "ErrSigDER",
ErrSigHighS: "ErrSigHighS",
ErrNotPushOnly: "ErrNotPushOnly",
ErrSigNullDummy: "ErrSigNullDummy",
ErrPubKeyType: "ErrPubKeyType",
ErrCleanStack: "ErrCleanStack",
ErrNullFail: "ErrNullFail",
ErrDiscourageUpgradableNOPs: "ErrDiscourageUpgradableNOPs",
ErrNegativeLockTime: "ErrNegativeLockTime",
ErrUnsatisfiedLockTime: "ErrUnsatisfiedLockTime",
ErrWitnessProgramEmpty: "ErrWitnessProgramEmpty",
ErrWitnessProgramMismatch: "ErrWitnessProgramMismatch",
ErrWitnessProgramWrongLength: "ErrWitnessProgramWrongLength",
ErrWitnessMalleated: "ErrWitnessMalleated",
ErrWitnessMalleatedP2SH: "ErrWitnessMalleatedP2SH",
ErrWitnessUnexpected: "ErrWitnessUnexpected",
ErrMinimalIf: "ErrMinimalIf",
ErrWitnessPubKeyType: "ErrWitnessPubKeyType",
ErrDiscourageUpgradableWitnessProgram: "ErrDiscourageUpgradableWitnessProgram",
}
// String returns the ErrorCode as a human-readable name.
func (e ErrorCode) String() string {
if s := errorCodeStrings[e]; s != "" {
return s
}
return fmt.Sprintf("Unknown ErrorCode (%d)", int(e))
}
// Error identifies a script-related error. It is used to indicate three
// classes of errors:
// 1) Script execution failures due to violating one of the many requirements
// imposed by the script engine or evaluating to false
// 2) Improper API usage by callers
// 3) Internal consistency check failures
//
// The caller can use type assertions on the returned errors to access the
// ErrorCode field to ascertain the specific reason for the error. As an
// additional convenience, the caller may make use of the IsErrorCode function
// to check for a specific error code.
type Error struct {
ErrorCode ErrorCode
Description string
}
// Error satisfies the error interface and prints human-readable errors.
func (e Error) Error() string {
return e.Description
}
// scriptError creates an Error given a set of arguments.
func scriptError(c ErrorCode, desc string) Error {
return Error{ErrorCode: c, Description: desc}
}
// IsErrorCode returns whether or not the provided error is a script error with
// the provided error code.
func IsErrorCode(err error, c ErrorCode) bool {
serr, ok := err.(Error)
return ok && serr.ErrorCode == c
}