vm: implement some kv business logic

Signed-off-by: Gyuho Lee <[email protected]>

Author: gyuho

vm/info/info.go

@@ -0,0 +1,21 @@
+// Copyright (C) 2019-2021, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+// Package info defines the key owner information.
+package info
+
+import (
+	"github.com/ava-labs/quarkvm/crypto/ed25519"
+	"github.com/ava-labs/quarkvm/vm/codec"
+)
+
+func init() {
+	codec.RegisterType(&Info{})
+}
+
+type Info struct {
+	Owner       ed25519.PublicKey `serialize:"true"`
+	LastUpdated int64             `serialize:"true"`
+	Expiry      int64             `serialize:"true"`
+	Keys        int64             `serialize:"true"` // decays faster the more keys you have
+}

vm/kv.go

@@ -0,0 +1,4 @@
+// Copyright (C) 2019-2021, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package vm

vm/storage/storage.go

@@ -10,6 +10,8 @@ import (
 	"github.com/ava-labs/avalanchego/database/prefixdb"
 	"github.com/ava-labs/avalanchego/database/versiondb"
 	"github.com/ava-labs/quarkvm/crypto/ed25519"
+	"github.com/ava-labs/quarkvm/vm/codec"
+	"github.com/ava-labs/quarkvm/vm/info"
 )
 
 var (
@@ -23,6 +25,10 @@ var (
 	keyPrefix = []byte("key")
 )
 
+var (
+	ErrKeyExists = errors.New("key already exists")
+)
+
 type Storage interface {
 	Block() database.Database
 	Info() database.Database
@@ -68,17 +74,49 @@ func (s *storage) Key() database.Database {
 	return s.keyDB
 }
 
+// any non-existent or expired (see below) key can be claimed
+// by anyone that submits a sufficient PoW.
 func (s *storage) Put(k []byte, v []byte, opts ...OpOption) error {
 	ret := &Op{}
 	ret.applyOpts(opts)
-	if ret.overwrite && ret.owner == nil {
+	if ret.owner == nil {
 		return errors.New("caller must provide the public key to make modification or overwrite")
 	}
 
-	// TODO: look up key
-	// if exists, only overwrite when conditions are met
-	// implement other business logic
+	if exist, _ := s.keyDB.Has(k); exist && !ret.overwrite {
+		return ErrKeyExists
+	}
+
+	// "a/b" then pfx is "a" and sub is "b"
+	pfx, sub, _, err := getPrefix(k)
+	if err != nil {
+		return err
+	}
+
+	// find the owner of the prefix
+	infoBytes, err := s.infoDB.Get(pfx)
+	if err != nil && err == database.ErrClosed {
+		// TODO: db returns error if not found?
+		return err
+	}
+
+	if len(infoBytes) > 0 {
+		// TODO: validate with public key
+		// where to get signature
+		ret.owner.Verify(infoBytes, nil)
+
+		// TODO: update the info key
+	} else {
+		info := &info.Info{Owner: ret.owner}
+		infoBytes, err := codec.Marshal(info)
+		if err != nil {
+			return err
+		}
+		s.infoDB.Put(pfx, infoBytes)
+	}
 
+	// if validated or new key,
+	// the owner is allowed to write the key
 	return s.keyDB.Put(k, v)
 }