core: vm: implement RAND opcode support

DEXON has a built-in on chain random oracle that allow one to retrieve a
random variable. Add a new opcode `RAND` to load the random variable
onto the stack.

4 files changed, 12 insertions, 0 deletions

diff --git a/core/types/block.go b/core/types/block.go
index b568c2b37..ef2cb2c56 100644
--- a/core/types/block.go
+++ b/core/types/block.go
@@ -83,6 +83,7 @@ type Header struct {
 	Extra       []byte         `json:"extraData"        gencodec:"required"`
 	MixDigest   common.Hash    `json:"mixHash"`
 	Nonce       BlockNonce     `json:"nonce"`
+	Randomness  []byte         `json:"randomness"       gencodec:"required"`
 }
 
 // field type overrides for gencodec
diff --git a/core/types/gen_header_json.go b/core/types/gen_header_json.go
index 4c028337f..d06b07769 100644
--- a/core/types/gen_header_json.go
+++ b/core/types/gen_header_json.go
@@ -31,6 +31,7 @@ func (h Header) MarshalJSON() ([]byte, error) {
 		Extra       hexutil.Bytes  `json:"extraData"        gencodec:"required"`
 		MixDigest   common.Hash    `json:"mixHash"`
 		Nonce       BlockNonce     `json:"nonce"`
+		Randomness  []byte         `json:"randomness"       gencodec:"required"`
 		Hash        common.Hash    `json:"hash"`
 	}
 	var enc Header
@@ -49,6 +50,7 @@ func (h Header) MarshalJSON() ([]byte, error) {
 	enc.Extra = h.Extra
 	enc.MixDigest = h.MixDigest
 	enc.Nonce = h.Nonce
+	enc.Randomness = h.Randomness
 	enc.Hash = h.Hash()
 	return json.Marshal(&enc)
 }
@@ -71,6 +73,7 @@ func (h *Header) UnmarshalJSON(input []byte) error {
 		Extra       *hexutil.Bytes  `json:"extraData"        gencodec:"required"`
 		MixDigest   *common.Hash    `json:"mixHash"`
 		Nonce       *BlockNonce     `json:"nonce"`
+		Randomness  []byte          `json:"randomness"       gencodec:"required"`
 	}
 	var dec Header
 	if err := json.Unmarshal(input, &dec); err != nil {
@@ -134,5 +137,9 @@ func (h *Header) UnmarshalJSON(input []byte) error {
 	if dec.Nonce != nil {
 		h.Nonce = *dec.Nonce
 	}
+	if dec.Randomness == nil {
+		return errors.New("missing required field 'randomness' for Header")
+	}
+	h.Randomness = dec.Randomness
 	return nil
 }
diff --git a/core/types/gen_log_json.go b/core/types/gen_log_json.go
index 4d24b92fd..e301a69c8 100644
--- a/core/types/gen_log_json.go
+++ b/core/types/gen_log_json.go
@@ -12,6 +12,7 @@ import (
 
 var _ = (*logMarshaling)(nil)
 
+// MarshalJSON marshals as JSON.
 func (l Log) MarshalJSON() ([]byte, error) {
 	type Log struct {
 		Address     common.Address `json:"address" gencodec:"required"`
@@ -37,6 +38,7 @@ func (l Log) MarshalJSON() ([]byte, error) {
 	return json.Marshal(&enc)
 }
 
+// UnmarshalJSON unmarshals from JSON.
 func (l *Log) UnmarshalJSON(input []byte) error {
 	type Log struct {
 		Address     *common.Address `json:"address" gencodec:"required"`
diff --git a/core/types/gen_tx_json.go b/core/types/gen_tx_json.go
index b1415094b..2f216dfb9 100644
--- a/core/types/gen_tx_json.go
+++ b/core/types/gen_tx_json.go
@@ -13,6 +13,7 @@ import (
 
 var _ = (*txdataMarshaling)(nil)
 
+// MarshalJSON marshals as JSON.
 func (t txdata) MarshalJSON() ([]byte, error) {
 	type txdata struct {
 		AccountNonce hexutil.Uint64  `json:"nonce"    gencodec:"required"`
@@ -40,6 +41,7 @@ func (t txdata) MarshalJSON() ([]byte, error) {
 	return json.Marshal(&enc)
 }
 
+// UnmarshalJSON unmarshals from JSON.
 func (t *txdata) UnmarshalJSON(input []byte) error {
 	type txdata struct {
 		AccountNonce *hexutil.Uint64 `json:"nonce"    gencodec:"required"`