This is a nice VM, it has an interesting stack items model, better separation
of elements from stack implementation, simpler stack implementation and a bit
nicer opcode implementation mechanism. At the same time it lacks so many
features and is so differing from our current VM (that is closely tied to the
compiler) that it makes its code very hard to reuse for master's VM
improvement.
Also, some differences are non-obvious to judge in terms of better or
worse. Stack item model seems to be more extensible, but at the same time we
know very well what kind of stack items we have and this doesn't change a
lot. Slice-based stack is simple but it's hard to say which one would perform
better for real-world smart contracts (it has different tradeoffs in
operations complexity).
Based on that, I'm dropping it. Some ideas will be reused during VM
refactoring, but no more than that. Refs. #307.
The code that we have actually implements XTUCK and not TUCK. And it's a bit
broken, so fix it and add some tests. The most interesting one (that required
to touch stack code) is the one when we have 1 element on the stack and are
trying to tell XTUCK to push 2 elements deep.
ANSI X9.62 says that if x or y coordinate are greater than or equal to
curve.Params().P, the conversion should return an error (see ANSI X9.62:2005
Section A.5.8 Step b, which invokes Section A.5.5, which does the check and
rejects when x or y are too big.
See https://github.com/golang/go/issues/20482 for more details.
PublicKey() for PrivateKey now just can't fail and it makes no sense to return
an error from it. There is a lot of associated functionality for which this
also is true, so adjust it accordingly and simplify a lot of code.
Public key is just a point, so use the coordinates obtained previously to
initialize the PublicKey structure without jumping through the hoops of
encoding/decoding.
As NEO uses P256 we can use standard crypto/elliptic library for almost
everything, the only exception being decompression of the Y coordinate. For
some reason the standard library only supports uncompressed format in its
Marshal()/Unmarshal() functions. elliptic.P256() is known to have
constant-time implementation, so it fixes#245 (and the decompression using
big.Int operates on public key, so nobody really cares about that part being
constant-time).
New decompress function is inspired by
https://stackoverflow.com/questions/46283760, even though the previous one
really did the same thing just in a little less obvious way.
It makes no sense to provide an API for throw-away public keys, so obtain it
via a new real keypair generation where appropriate (and that's only needed
for testing).
Golint:
pkg/rpc/rpc.go:15:67: exported method GetBlock returns unexported type *rpc.response, which can be annoying to use
pkg/rpc/rpc.go:82:64: exported method GetRawTransaction returns unexported type *rpc.response, which can be annoying to use
pkg/rpc/rpc.go:97:52: exported method SendRawTransaction returns unexported type *rpc.response, which can be annoying to use
Refs. #213.
pkg/rpc/neoScanBalanceGetter.go:54:56: method parameter assetIdUint should be assetIDUint
pkg/rpc/neoScanBalanceGetter.go:62:3: var assetId should be assetID
pkg/rpc/server_test.go:27:5: var testRpcCases should be testRPCCases
pkg/rpc/txTypes.go:19:3: struct field assetId should be assetID
pkg/rpc/txTypes.go:39:35: interface method parameter assetId should be assetID
pkg/rpc/types.go:115:2: struct field TxId should be TxID
Refs. #213.
pkg/core/transaction/attribute.go:67:14: should omit type uint8 from declaration of var urllen; it will be inferred from the right-hand side
pkg/crypto/keys/publickey.go:184:8: should omit type []byte from declaration of var b; it will be inferred from the right-hand side
pkg/network/payload/version_test.go:15:12: should omit type bool from declaration of var relay; it will be inferred from the right-hand side
Refs. #213.
Golint:
pkg/core/blockchain.go:796:9: if block ends with a return statement, so drop
this else and outdent its block (move short variable declaration to its own
line if necessary)
Refs. #213.
Fixes things like:
* exported type/method/function X should have comment or be unexported
* comment on exported type/method/function X should be of the form "X ..."
(with optional leading article)
Refs. #213.
The big delete (#307) series episode six airs today for every subscriber of the neo-go repo (previous episodes: #315, #318, #322, #328, #330).
This one is easy, nothing moved, just the red things.
This fixes two minor things observed in #96:
running VM twice, which leads to instruction execution attempt for VM in FAULT state
panicing with nil dereference (it's better to show some error message)
Before this patchset:
NEO-GO-VM > run
NEO-GO-VM > error encountered at instruction 6 (ROLL)
NEO-GO-VM > runtime error: invalid memory address or nil pointer dereference
FAULT
NEO-GO-VM > error encountered at instruction 7 (SETITEM)
NEO-GO-VM > interface conversion: interface {} is []vm.StackItem, not []uint8
After this patchset:
NEO-GO-VM > run
NEO-GO-VM > error encountered at instruction 6 (ROLL)
NEO-GO-VM > bad index
FAULT
Fixes one more instruction being ran when VM FAULTs:
NEO-GO-VM > run
NEO-GO-VM > error encountered at instruction 6 (ROLL)
NEO-GO-VM > runtime error: invalid memory address or nil pointer dereference
FAULT
NEO-GO-VM > error encountered at instruction 7 (SETITEM)
NEO-GO-VM > interface conversion: interface {} is []vm.StackItem, not []uint8
Refs. #96.
