Added prefix for DARC storage

.editorconfig

@@ -49,4 +49,4 @@ ij_go_wrap_func_params_newline_after_lparen = true
 ij_go_wrap_func_params_newline_before_rparen = true
 ij_go_wrap_func_result = on_every_item
 ij_go_wrap_func_result_newline_after_lparen = true
-ij_go_wrap_func_result_newline_before_rparen = true
+ij_go_wrap_func_result_newline_before_rparen = true

contracts/access/access.go

@@ -27,6 +27,10 @@ import (
 )
 
 const (
+	// ContractUID is the unique (4-bytes) identifier of the contract, it is
+	// used to prefix keys in the K/V store and by DARCs for access control.
+	ContractUID = "DARC"
+
 	// ContractName is the name of the access contract.
 	ContractName = "go.dedis.ch/dela.Access"
 
@@ -50,9 +54,9 @@ const (
 	// run on the contract. Should be one of the Command type.
 	CmdArg = "access:command"
 
-	// credentialAllCommand defines the credential command that is allowed to
+	// CredentialAllCommand defines the credential command that is allowed to
 	// perform all commands.
-	credentialAllCommand = "all"
+	CredentialAllCommand = "all"
 )
 
 // Command defines a command for the command contract
@@ -64,8 +68,8 @@ const (
 )
 
 // NewCreds creates new credentials for an access contract execution.
-func NewCreds(id []byte) access.Credential {
-	return access.NewContractCreds(id, ContractName, credentialAllCommand)
+func NewCreds() access.Credential {
+	return access.NewContractCreds([]byte(ContractUID), ContractName, CredentialAllCommand)
 }
 
 // RegisterContract registers the access contract to the given execution
@@ -81,24 +85,20 @@ type Contract struct {
 	// access is the access service that will be modified.
 	access access.Service
 
-	// accessKey is the credential's ID allowed to use this smart contract
-	accessKey []byte
-
 	store store.Readable
 }
 
 // NewContract creates a new access contract
-func NewContract(aKey []byte, srvc access.Service, store store.Readable) Contract {
+func NewContract(srvc access.Service, store store.Readable) Contract {
 	return Contract{
-		access:    srvc,
-		accessKey: aKey,
-		store:     store,
+		access: srvc,
+		store:  store,
 	}
 }
 
 // Execute implements native.Contract
 func (c Contract) Execute(snap store.Snapshot, step execution.Step) error {
-	creds := NewCreds(c.accessKey)
+	creds := NewCreds()
 
 	err := c.access.Match(c.store, creds, step.Current.GetIdentity())
 	if err != nil {
@@ -123,6 +123,13 @@ func (c Contract) Execute(snap store.Snapshot, step execution.Step) error {
 	return nil
 }
 
+// UID returns the unique 4-bytes contract identifier.
+//
+// - implements native.Contract
+func (c Contract) UID() string {
+	return ContractUID
+}
+
 // grant perform the GRANT command
 func (c Contract) grant(snap store.Snapshot, step execution.Step) error {
 	idHex := step.Current.GetArg(GrantIDArg)

contracts/access/access_test.go

@@ -16,12 +16,12 @@ import (
 )
 
 func TestExecute(t *testing.T) {
-	contract := NewContract([]byte{}, fakeAccess{err: fake.GetError()}, fakeStore{})
+	contract := NewContract(fakeAccess{err: fake.GetError()}, fakeStore{})
 	err := contract.Execute(fakeStore{}, makeStep(t, CmdArg, ""))
 	require.EqualError(t, err,
 		"identity not authorized: fake.PublicKey ("+fake.GetError().Error()+")")
 
-	contract = NewContract([]byte{}, fakeAccess{}, fakeStore{})
+	contract = NewContract(fakeAccess{}, fakeStore{})
 	err = contract.Execute(fakeStore{}, makeStep(t, CmdArg, ""))
 	require.EqualError(t, err, "'access:command' not found in tx arg")
 
@@ -44,7 +44,7 @@ func TestExecute(t *testing.T) {
 }
 
 func TestGrant(t *testing.T) {
-	contract := NewContract([]byte{}, fakeAccess{}, fakeStore{})
+	contract := NewContract(fakeAccess{}, fakeStore{})
 	err := contract.grant(fakeStore{}, makeStep(t))
 	require.EqualError(t, err, "'access:grant_id' not found in tx arg")
 
@@ -86,7 +86,7 @@ func TestGrant(t *testing.T) {
 		IdentityArg, id))
 	require.NoError(t, err)
 
-	contract = NewContract([]byte{}, fakeAccess{err: fake.GetError()}, fakeStore{})
+	contract = NewContract(fakeAccess{err: fake.GetError()}, fakeStore{})
 	err = contract.grant(fakeStore{}, makeStep(t, GrantIDArg, "deadbeef",
 		GrantContractArg, "fake contract",
 		GrantCommandArg, "fake command",

contracts/access/controller/action.go

@@ -49,7 +49,7 @@ func (a addAction) Execute(ctx node.Context) error {
 		return xerrors.Errorf("failed to parse identities: %v", err)
 	}
 
-	err = asrv.Grant(accessStore, accessContract.NewCreds(aKey[:]), identities...)
+	err = asrv.Grant(accessStore, accessContract.NewCreds(), identities...)
 	if err != nil {
 		return xerrors.Errorf("failed to grant: %v", err)
 	}

contracts/access/controller/controller.go

@@ -14,8 +14,6 @@ import (
 	"golang.org/x/xerrors"
 )
 
-var aKey = [32]byte{1}
-
 // newStore is the function used to create the new store. It allows us to create
 // a different store in the tests.
 var newStore = func(path string) (accessStore, error) {
@@ -68,7 +66,7 @@ func (m miniController) OnStart(flags cli.Flags, inj node.Injector) error {
 		return xerrors.Errorf("failed to create access store: %v", err)
 	}
 
-	contract := accessContract.NewContract(aKey[:], access, accessStore)
+	contract := accessContract.NewContract(access, accessStore)
 	accessContract.RegisterContract(exec, contract)
 
 	inj.Inject(accessStore)

contracts/value/controller/controller.go

@@ -9,9 +9,6 @@ import (
 	"golang.org/x/xerrors"
 )
 
-// aKey is the access key used for the value contract
-var aKey = [32]byte{2}
-
 // miniController is a CLI initializer to register the value contract
 //
 // - implements node.Initializer
@@ -41,7 +38,7 @@ func (m miniController) OnStart(flags cli.Flags, inj node.Injector) error {
 		return xerrors.Errorf("failed to resolve native service: %v", err)
 	}
 
-	contract := value.NewContract(aKey[:], access)
+	contract := value.NewContract(access)
 
 	value.RegisterContract(exec, contract)
 

contracts/value/value.go

@@ -13,6 +13,7 @@ import (
 	"go.dedis.ch/dela/core/execution"
 	"go.dedis.ch/dela/core/execution/native"
 	"go.dedis.ch/dela/core/store"
+	"go.dedis.ch/dela/core/store/prefixed"
 	"golang.org/x/xerrors"
 )
 
@@ -26,6 +27,10 @@ type commands interface {
 }
 
 const (
+	// ContractUID is the unique (4-bytes) identifier of the contract, it is
+	// used to prefix keys in the K/V store and by DARCs for access control.
+	ContractUID = "VALU"
+
 	// ContractName is the name of the contract.
 	ContractName = "go.dedis.ch/dela.Value"
 
@@ -41,12 +46,9 @@ const (
 	// run on the contract. Should be one of the Command type.
 	CmdArg = "value:command"
 
-	// credentialAllCommand defines the credential command that is allowed to
+	// CredentialAllCommand defines the credential command that is allowed to
 	// perform all commands.
-	credentialAllCommand = "all"
-
-	// contractKeyPrefix is used to prefix keys in the K/V store.
-	contractKeyPrefix = "VALU" // intentionally 4 bytes only, not a typo!
+	CredentialAllCommand = "all"
 )
 
 // Command defines a type of command for the value contract
@@ -69,8 +71,8 @@ const (
 
 // NewCreds creates new credentials for a value contract execution. We might
 // want to use in the future a separate credential for each command.
-func NewCreds(id []byte) access.Credential {
-	return access.NewContractCreds(id, ContractName, credentialAllCommand)
+func NewCreds() access.Credential {
+	return access.NewContractCreds([]byte(ContractUID), ContractName, CredentialAllCommand)
 }
 
 // RegisterContract registers the value contract to the given execution service.
@@ -89,9 +91,6 @@ type Contract struct {
 	// access is the access control service managing this smart contract
 	access access.Service
 
-	// accessKey is the access identifier allowed to use this smart contract
-	accessKey []byte
-
 	// cmd provides the commands that can be executed by this smart contract
 	cmd commands
 
@@ -100,12 +99,11 @@ type Contract struct {
 }
 
 // NewContract creates a new Value contract
-func NewContract(aKey []byte, srvc access.Service) Contract {
+func NewContract(srvc access.Service) Contract {
 	contract := Contract{
-		index:     map[string]struct{}{},
-		access:    srvc,
-		accessKey: aKey,
-		printer:   infoLog{},
+		index:   map[string]struct{}{},
+		access:  srvc,
+		printer: infoLog{},
 	}
 
 	contract.cmd = valueCommand{Contract: &contract}
@@ -115,7 +113,7 @@ func NewContract(aKey []byte, srvc access.Service) Contract {
 
 // Execute implements native.Contract. It runs the appropriate command.
 func (c Contract) Execute(snap store.Snapshot, step execution.Step) error {
-	creds := NewCreds(c.accessKey)
+	creds := NewCreds()
 
 	err := c.access.Match(snap, creds, step.Current.GetIdentity())
 	if err != nil {
@@ -128,6 +126,8 @@ func (c Contract) Execute(snap store.Snapshot, step execution.Step) error {
 		return xerrors.Errorf("'%s' not found in tx arg", CmdArg)
 	}
 
+	snap = prefixed.NewSnapshot(ContractUID, snap)
+
 	switch Command(cmd) {
 	case CmdWrite:
 		err := c.cmd.write(snap, step)
@@ -156,6 +156,13 @@ func (c Contract) Execute(snap store.Snapshot, step execution.Step) error {
 	return nil
 }
 
+// UID returns the unique 4-bytes contract identifier.
+//
+// - implements native.Contract
+func (c Contract) UID() string {
+	return ContractUID
+}
+
 // valueCommand implements the commands of the value contract
 //
 // - implements commands
@@ -175,8 +182,7 @@ func (c valueCommand) write(snap store.Snapshot, step execution.Step) error {
 		return xerrors.Errorf("'%s' not found in tx arg", ValueArg)
 	}
 
-	snapKey := prefix(key)
-	err := snap.Set(snapKey, value)
+	err := snap.Set(key, value)
 	if err != nil {
 		return xerrors.Errorf("failed to set value: %v", err)
 	}
@@ -185,7 +191,7 @@ func (c valueCommand) write(snap store.Snapshot, step execution.Step) error {
 
 	dela.Logger.Info().
 		Str("contract", ContractName).
-		Msgf("setting value %x=%s", snapKey, value)
+		Msgf("setting value %x=%s", key, value)
 
 	return nil
 }
@@ -197,7 +203,7 @@ func (c valueCommand) read(snap store.Snapshot, step execution.Step) error {
 		return xerrors.Errorf("'%s' not found in tx arg", KeyArg)
 	}
 
-	val, err := snap.Get(prefix(key))
+	val, err := snap.Get(key)
 	if err != nil {
 		return xerrors.Errorf("failed to get key '%s': %v", key, err)
 	}
@@ -214,8 +220,7 @@ func (c valueCommand) delete(snap store.Snapshot, step execution.Step) error {
 		return xerrors.Errorf("'%s' not found in tx arg", KeyArg)
 	}
 
-	snapKey := prefix(key)
-	err := snap.Delete(snapKey)
+	err := snap.Delete(key)
 	if err != nil {
 		return xerrors.Errorf("failed to delete key '%x': %v", key, err)
 	}
@@ -224,7 +229,7 @@ func (c valueCommand) delete(snap store.Snapshot, step execution.Step) error {
 
 	dela.Logger.Info().
 		Str("contract", ContractName).
-		Msgf("deleting value %x", snapKey)
+		Msgf("deleting value %x", key)
 
 	return nil
 }
@@ -234,7 +239,7 @@ func (c valueCommand) list(snap store.Snapshot) error {
 	res := []string{}
 
 	for k := range c.index {
-		v, err := snap.Get(prefix([]byte(k)))
+		v, err := snap.Get([]byte(k))
 		if err != nil {
 			return xerrors.Errorf("failed to get key '%s': %v", k, err)
 		}
@@ -258,7 +263,3 @@ func (h infoLog) Write(p []byte) (int, error) {
 
 	return len(p), nil
 }
-
-func prefix(key []byte) []byte {
-	return append([]byte(contractKeyPrefix), key...)
-}