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txscript: Change makeScriptNum to take a length argument
While current existing numeric opcodes are limited to 4 bytes, new opcodes may need different limits. This mimics Bitcoin Core commit 99088d60d8a7747c6d1a7fd5d8cd388be1b3e138
This commit is contained in:
David Hill
parent
e4c053e504
commit
ce22159fb2
@ -8,9 +8,9 @@ const (
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maxInt32 = 1<<31 - 1
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minInt32 = -1 << 31
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// maxScriptNumLen is the maximum number of bytes data being interpreted
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// as an integer may be.
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maxScriptNumLen = 4
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// defaultScriptNumLen is the default number of bytes
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// data being interpreted as an integer may be.
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defaultScriptNumLen = 4
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)
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// scriptNum represents a numeric value used in the scripting engine with
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@ -36,9 +36,9 @@ const (
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//
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// Then, whenever data is interpreted as an integer, it is converted to this
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// type by using the makeScriptNum function which will return an error if the
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// number is out of range (or not minimally encoded depending on a flag). Since
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// all numeric opcodes involve pulling data from the stack and interpreting it
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// as an integer, it provides the required behavior.
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// number is out of range or not minimally encoded depending on parameters.
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// Since all numeric opcodes involve pulling data from the stack and
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// interpreting it as an integer, it provides the required behavior.
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type scriptNum int64
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// checkMinimalDataEncoding returns whether or not the passed byte array adheres
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@ -132,11 +132,12 @@ func (n scriptNum) Bytes() []byte {
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// and the consensus rules dictate numbers which are directly cast to ints
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// provide this behavior.
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//
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// In practice, the number should never really be out of range since it will
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// have been created with makeScriptNum which rejects them, but in case
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// something in the future ends up calling this function against the result
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// of some arithmetic, which IS allowed to be out of range before being
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// reinterpreted as an integer, this will provide the correct behavior.
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// In practice, for most opcodes, the number should never be out of range since
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// it will have been created with makeScriptNum using the defaultScriptLen
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// value, which rejects them. In case something in the future ends up calling
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// this function against the result of some arithmetic, which IS allowed to be
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// out of range before being reinterpreted as an integer, this will provide the
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// correct behavior.
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func (n scriptNum) Int32() int32 {
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if n > maxInt32 {
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return maxInt32
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@ -152,10 +153,13 @@ func (n scriptNum) Int32() int32 {
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// makeScriptNum interprets the passed serialized bytes as an encoded integer
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// and returns the result as a script number.
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//
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// Since the consensus rules dictate the serialized bytes interpreted as ints
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// are only allowed to be in the range [-2^31 + 1, 2^31 - 1], an error will be
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// returned when the provided bytes would result in a number outside of that
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// range.
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// Since the consensus rules dictate that serialized bytes interpreted as ints
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// are only allowed to be in the range determined by a maximum number of bytes,
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// on a per opcode basis, an error will be returned when the provided bytes
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// would result in a number outside of that range. In particular, the range for
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// the vast majority of opcodes dealing with numeric values are limited to 4
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// bytes and therefore will pass that value to this function resulting in an
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// allowed range of [-2^31 + 1, 2^31 - 1].
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//
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// The requireMinimal flag causes an error to be returned if additional checks
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// on the encoding determine it is not represented with the smallest possible
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@ -164,11 +168,18 @@ func (n scriptNum) Int32() int32 {
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// [0x7f 0x00 0x00 ...], etc. All forms except [0x7f] will return an error with
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// requireMinimal enabled.
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//
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// The scriptNumLen is the maximum number of bytes the encoded value can be
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// before an ErrStackNumberTooBig is returned. This effectively limits the
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// range of allowed values.
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// WARNING: Great care should be taken if passing a value larger than
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// defaultScriptNumLen, which could lead to addition and multiplication
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// overflows.
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//
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// See the Bytes function documentation for example encodings.
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func makeScriptNum(v []byte, requireMinimal bool) (scriptNum, error) {
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// Interpreting data as an integer requires that it is not larger than
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// a 32-bit integer.
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if len(v) > maxScriptNumLen {
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func makeScriptNum(v []byte, requireMinimal bool, scriptNumLen int) (scriptNum, error) {
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// Interpreting data requires that it is not larger than
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// the the passed scriptNumLen value.
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if len(v) > scriptNumLen {
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return 0, ErrStackNumberTooBig
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}
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@ -94,90 +94,102 @@ func TestMakeScriptNum(t *testing.T) {
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tests := []struct {
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serialized []byte
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num scriptNum
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numLen int
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minimalEncoding bool
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err error
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}{
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// Minimal encoding must reject negative 0.
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{hexToBytes("80"), 0, true, ErrStackMinimalData},
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{hexToBytes("80"), 0, defaultScriptNumLen, true, ErrStackMinimalData},
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// Minimally encoded valid values with minimal encoding flag.
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// Should not error and return expected integral number.
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{nil, 0, true, nil},
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{hexToBytes("01"), 1, true, nil},
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{hexToBytes("81"), -1, true, nil},
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{hexToBytes("7f"), 127, true, nil},
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{hexToBytes("ff"), -127, true, nil},
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{hexToBytes("8000"), 128, true, nil},
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{hexToBytes("8080"), -128, true, nil},
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{hexToBytes("8100"), 129, true, nil},
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{hexToBytes("8180"), -129, true, nil},
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{hexToBytes("0001"), 256, true, nil},
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{hexToBytes("0081"), -256, true, nil},
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{hexToBytes("ff7f"), 32767, true, nil},
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{hexToBytes("ffff"), -32767, true, nil},
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{hexToBytes("008000"), 32768, true, nil},
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{hexToBytes("008080"), -32768, true, nil},
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{hexToBytes("ffff00"), 65535, true, nil},
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{hexToBytes("ffff80"), -65535, true, nil},
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{hexToBytes("000008"), 524288, true, nil},
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{hexToBytes("000088"), -524288, true, nil},
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{hexToBytes("000070"), 7340032, true, nil},
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{hexToBytes("0000f0"), -7340032, true, nil},
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{hexToBytes("00008000"), 8388608, true, nil},
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{hexToBytes("00008080"), -8388608, true, nil},
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{hexToBytes("ffffff7f"), 2147483647, true, nil},
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{hexToBytes("ffffffff"), -2147483647, true, nil},
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{nil, 0, defaultScriptNumLen, true, nil},
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{hexToBytes("01"), 1, defaultScriptNumLen, true, nil},
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{hexToBytes("81"), -1, defaultScriptNumLen, true, nil},
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{hexToBytes("7f"), 127, defaultScriptNumLen, true, nil},
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{hexToBytes("ff"), -127, defaultScriptNumLen, true, nil},
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{hexToBytes("8000"), 128, defaultScriptNumLen, true, nil},
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{hexToBytes("8080"), -128, defaultScriptNumLen, true, nil},
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{hexToBytes("8100"), 129, defaultScriptNumLen, true, nil},
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{hexToBytes("8180"), -129, defaultScriptNumLen, true, nil},
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{hexToBytes("0001"), 256, defaultScriptNumLen, true, nil},
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{hexToBytes("0081"), -256, defaultScriptNumLen, true, nil},
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{hexToBytes("ff7f"), 32767, defaultScriptNumLen, true, nil},
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{hexToBytes("ffff"), -32767, defaultScriptNumLen, true, nil},
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{hexToBytes("008000"), 32768, defaultScriptNumLen, true, nil},
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{hexToBytes("008080"), -32768, defaultScriptNumLen, true, nil},
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{hexToBytes("ffff00"), 65535, defaultScriptNumLen, true, nil},
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{hexToBytes("ffff80"), -65535, defaultScriptNumLen, true, nil},
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{hexToBytes("000008"), 524288, defaultScriptNumLen, true, nil},
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{hexToBytes("000088"), -524288, defaultScriptNumLen, true, nil},
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{hexToBytes("000070"), 7340032, defaultScriptNumLen, true, nil},
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{hexToBytes("0000f0"), -7340032, defaultScriptNumLen, true, nil},
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{hexToBytes("00008000"), 8388608, defaultScriptNumLen, true, nil},
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{hexToBytes("00008080"), -8388608, defaultScriptNumLen, true, nil},
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{hexToBytes("ffffff7f"), 2147483647, defaultScriptNumLen, true, nil},
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{hexToBytes("ffffffff"), -2147483647, defaultScriptNumLen, true, nil},
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{hexToBytes("ffffffff7f"), 549755813887, 5, true, nil},
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{hexToBytes("ffffffffff"), -549755813887, 5, true, nil},
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{hexToBytes("ffffffffffffff7f"), 9223372036854775807, 8, true, nil},
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{hexToBytes("ffffffffffffffff"), -9223372036854775807, 8, true, nil},
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{hexToBytes("ffffffffffffffff7f"), -1, 9, true, nil},
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{hexToBytes("ffffffffffffffffff"), 1, 9, true, nil},
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{hexToBytes("ffffffffffffffffff7f"), -1, 10, true, nil},
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{hexToBytes("ffffffffffffffffffff"), 1, 10, true, nil},
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// Minimally encoded values that are out of range for data that
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// is interpreted as script numbers with the minimal encoding
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// flag set. Should error and return 0.
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{hexToBytes("0000008000"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("0000008080"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("0000009000"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("0000009080"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffff00"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffff80"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("0000000001"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("0000000081"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffffffff00"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffffffff80"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffffffffff00"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffffffffff80"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffffffffff7f"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffffffffffff"), 0, true, ErrStackNumberTooBig},
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{hexToBytes("0000008000"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("0000008080"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("0000009000"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("0000009080"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffff00"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffff80"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("0000000001"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("0000000081"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffffffff00"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffffffff80"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffffffffff00"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffffffffff80"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffffffffff7f"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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{hexToBytes("ffffffffffffffff"), 0, defaultScriptNumLen, true, ErrStackNumberTooBig},
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// Non-minimally encoded, but otherwise valid values with
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// minimal encoding flag. Should error and return 0.
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{hexToBytes("00"), 0, true, ErrStackMinimalData}, // 0
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{hexToBytes("0100"), 0, true, ErrStackMinimalData}, // 1
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{hexToBytes("7f00"), 0, true, ErrStackMinimalData}, // 127
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{hexToBytes("800000"), 0, true, ErrStackMinimalData}, // 128
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{hexToBytes("810000"), 0, true, ErrStackMinimalData}, // 129
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{hexToBytes("000100"), 0, true, ErrStackMinimalData}, // 256
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{hexToBytes("ff7f00"), 0, true, ErrStackMinimalData}, // 32767
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{hexToBytes("00800000"), 0, true, ErrStackMinimalData}, // 32768
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{hexToBytes("ffff0000"), 0, true, ErrStackMinimalData}, // 65535
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{hexToBytes("00000800"), 0, true, ErrStackMinimalData}, // 524288
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{hexToBytes("00007000"), 0, true, ErrStackMinimalData}, // 7340032
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{hexToBytes("00"), 0, defaultScriptNumLen, true, ErrStackMinimalData}, // 0
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{hexToBytes("0100"), 0, defaultScriptNumLen, true, ErrStackMinimalData}, // 1
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{hexToBytes("7f00"), 0, defaultScriptNumLen, true, ErrStackMinimalData}, // 127
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{hexToBytes("800000"), 0, defaultScriptNumLen, true, ErrStackMinimalData}, // 128
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{hexToBytes("810000"), 0, defaultScriptNumLen, true, ErrStackMinimalData}, // 129
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{hexToBytes("000100"), 0, defaultScriptNumLen, true, ErrStackMinimalData}, // 256
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{hexToBytes("ff7f00"), 0, defaultScriptNumLen, true, ErrStackMinimalData}, // 32767
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{hexToBytes("00800000"), 0, defaultScriptNumLen, true, ErrStackMinimalData}, // 32768
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{hexToBytes("ffff0000"), 0, defaultScriptNumLen, true, ErrStackMinimalData}, // 65535
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{hexToBytes("00000800"), 0, defaultScriptNumLen, true, ErrStackMinimalData}, // 524288
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{hexToBytes("00007000"), 0, defaultScriptNumLen, true, ErrStackMinimalData}, // 7340032
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{hexToBytes("0009000100"), 0, 5, true, ErrStackMinimalData}, // 16779520
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// Non-minimally encoded, but otherwise valid values without
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// minimal encoding flag. Should not error and return expected
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// integral number.
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{hexToBytes("00"), 0, false, nil},
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{hexToBytes("0100"), 1, false, nil},
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{hexToBytes("7f00"), 127, false, nil},
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{hexToBytes("800000"), 128, false, nil},
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{hexToBytes("810000"), 129, false, nil},
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{hexToBytes("000100"), 256, false, nil},
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{hexToBytes("ff7f00"), 32767, false, nil},
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{hexToBytes("00800000"), 32768, false, nil},
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{hexToBytes("ffff0000"), 65535, false, nil},
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{hexToBytes("00000800"), 524288, false, nil},
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{hexToBytes("00007000"), 7340032, false, nil},
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{hexToBytes("00"), 0, defaultScriptNumLen, false, nil},
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{hexToBytes("0100"), 1, defaultScriptNumLen, false, nil},
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{hexToBytes("7f00"), 127, defaultScriptNumLen, false, nil},
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{hexToBytes("800000"), 128, defaultScriptNumLen, false, nil},
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{hexToBytes("810000"), 129, defaultScriptNumLen, false, nil},
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{hexToBytes("000100"), 256, defaultScriptNumLen, false, nil},
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{hexToBytes("ff7f00"), 32767, defaultScriptNumLen, false, nil},
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{hexToBytes("00800000"), 32768, defaultScriptNumLen, false, nil},
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{hexToBytes("ffff0000"), 65535, defaultScriptNumLen, false, nil},
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{hexToBytes("00000800"), 524288, defaultScriptNumLen, false, nil},
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{hexToBytes("00007000"), 7340032, defaultScriptNumLen, false, nil},
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{hexToBytes("0009000100"), 16779520, 5, false, nil},
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}
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for _, test := range tests {
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gotNum, err := makeScriptNum(test.serialized, test.minimalEncoding)
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gotNum, err := makeScriptNum(test.serialized, test.minimalEncoding,
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test.numLen)
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if err != test.err {
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t.Errorf("makeScriptNum: did not received expected "+
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"error for %x - got %v, want %v",
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@ -83,7 +83,7 @@ func (s *stack) PopInt() (scriptNum, error) {
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return 0, err
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}
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return makeScriptNum(so, s.verifyMinimalData)
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return makeScriptNum(so, s.verifyMinimalData, defaultScriptNumLen)
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}
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// PopBool pops the value off the top of the stack, converts it into a bool, and
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@ -118,7 +118,7 @@ func (s *stack) PeekInt(idx int32) (scriptNum, error) {
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return 0, err
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}
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return makeScriptNum(so, s.verifyMinimalData)
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return makeScriptNum(so, s.verifyMinimalData, defaultScriptNumLen)
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}
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// PeekBool returns the Nth item on the stack as a bool without removing it.
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