swarm, swap: pass chequebook address at start-up (ethersphere#1718)

swarm, swap: use passed --chequebook param, swap: don't use chequebookAddress on swap.new, create function NewInstanceAt

- updated call to swap.New in tests
- swapEnabled err checking
- updated comment at NewInstanceAt
- error handling and renaming
- rename InstanceAt to BindToContract
- refactor => chequebook setup in swap, remove verifyContract
- err returning and err handling

Author: Eknir

swap/protocol.go

@@ -97,7 +97,7 @@ func (s *Swap) verifyHandshake(msg interface{}) error {
 		return ErrEmptyAddressInSignature
 	}
 
-	return s.verifyContract(context.Background(), handshake.ContractAddress)
+	return contract.ValidateCode(context.Background(), s.backend, handshake.ContractAddress)
 }
 
 // run is the actual swap protocol run method

swap/swap.go

@@ -86,14 +86,14 @@ func NewParams() *Params {
 }
 
 // New - swap constructor
-func New(stateStore state.Store, prvkey *ecdsa.PrivateKey, contract common.Address, backend contract.Backend) *Swap {
+func New(stateStore state.Store, prvkey *ecdsa.PrivateKey, backend contract.Backend) *Swap {
 	return &Swap{
 		store:               stateStore,
 		balances:            make(map[enode.ID]int64),
 		cheques:             make(map[enode.ID]*Cheque),
 		peers:               make(map[enode.ID]*Peer),
 		backend:             backend,
-		owner:               createOwner(prvkey, contract),
+		owner:               createOwner(prvkey),
 		params:              NewParams(),
 		paymentThreshold:    DefaultPaymentThreshold,
 		disconnectThreshold: DefaultDisconnectThreshold,
@@ -127,13 +127,12 @@ func keyToID(key string, prefix string) enode.ID {
 }
 
 // createOwner assings keys and addresses
-func createOwner(prvkey *ecdsa.PrivateKey, contract common.Address) *Owner {
+func createOwner(prvkey *ecdsa.PrivateKey) *Owner {
 	pubkey := &prvkey.PublicKey
 	return &Owner{
+		address:    crypto.PubkeyToAddress(*pubkey),
 		privateKey: prvkey,
 		publicKey:  pubkey,
-		Contract:   contract,
-		address:    crypto.PubkeyToAddress(*pubkey),
 	}
 }
 
@@ -522,9 +521,9 @@ func (s *Swap) GetParams() *swap.Params {
 	return s.contract.ContractParams()
 }
 
-// verifyContract checks if the bytecode found at address matches the expected bytecode
-func (s *Swap) verifyContract(ctx context.Context, address common.Address) error {
-	return contract.ValidateCode(ctx, s.backend, address)
+// setChequebookAddr sets the chequebook address
+func (s *Swap) setChequebookAddr(chequebookAddr common.Address) {
+	s.owner.Contract = chequebookAddr
 }
 
 // getContractOwner retrieve the owner of the chequebook at address from the blockchain
@@ -537,8 +536,38 @@ func (s *Swap) getContractOwner(ctx context.Context, address common.Address) (co
 	return contr.Issuer(nil)
 }
 
-// Deploy deploys the Swap contract
-func (s *Swap) Deploy(ctx context.Context, backend swap.Backend, path string) error {
+// StartChequebook deploys a new instance of a chequebook if chequebookAddr is empty, otherwise it wil bind to an existing instance
+func (s *Swap) StartChequebook(chequebookAddr common.Address) error {
+	if chequebookAddr != (common.Address{}) {
+		if err := s.BindToContractAt(chequebookAddr); err != nil {
+			return err
+		}
+		log.Info("Using the provided chequebook", "chequebookAddr", chequebookAddr)
+	} else {
+		if err := s.Deploy(context.Background(), s.backend); err != nil {
+			return err
+		}
+		log.Info("New SWAP contract deployed", "contract info", s.DeploySuccess())
+	}
+	return nil
+}
+
+// BindToContractAt binds an instance of an already existing chequebook contract at address and sets chequebookAddr
+func (s *Swap) BindToContractAt(address common.Address) (err error) {
+
+	if err := contract.ValidateCode(context.Background(), s.backend, address); err != nil {
+		return fmt.Errorf("contract validation for %v failed: %v", address, err)
+	}
+	s.contract, err = contract.InstanceAt(address, s.backend)
+	if err != nil {
+		return err
+	}
+	s.setChequebookAddr(address)
+	return nil
+}
+
+// Deploy deploys the Swap contract and sets the contract address
+func (s *Swap) Deploy(ctx context.Context, backend swap.Backend) error {
 	opts := bind.NewKeyedTransactor(s.owner.privateKey)
 	// initial topup value
 	opts.Value = big.NewInt(int64(s.params.InitialDepositAmount))
@@ -550,7 +579,7 @@ func (s *Swap) Deploy(ctx context.Context, backend swap.Backend, path string) er
 		log.Error("unable to deploy swap", "error", err)
 		return err
 	}
-	s.owner.Contract = address
+	s.setChequebookAddr(address)
 	log.Info("swap deployed", "address", address.Hex(), "owner", opts.From.Hex())
 
 	return err

swap/swap_test.go

@@ -502,7 +502,7 @@ func newBaseTestSwap(t *testing.T, key *ecdsa.PrivateKey) (*Swap, string) {
 	}
 	log.Debug("creating simulated backend")
 
-	swap := New(stateStore, key, common.Address{}, testBackend)
+	swap := New(stateStore, key, testBackend)
 	return swap, dir
 }
 
@@ -644,8 +644,8 @@ func TestVerifyChequeInvalidSignature(t *testing.T) {
 	}
 }
 
-// tests if verifyContract accepts an address with the correct bytecode
-func TestVerifyContract(t *testing.T) {
+// tests if TestValidateCode accepts an address with the correct bytecode
+func TestValidateCode(t *testing.T) {
 	swap, clean := newTestSwap(t, ownerKey)
 	defer clean()
 
@@ -658,13 +658,13 @@ func TestVerifyContract(t *testing.T) {
 
 	testBackend.Commit()
 
-	if err = swap.verifyContract(context.TODO(), addr); err != nil {
+	if err = cswap.ValidateCode(context.TODO(), swap.backend, addr); err != nil {
 		t.Fatalf("Contract verification failed: %v", err)
 	}
 }
 
-// tests if verifyContract rejects an address with different bytecode
-func TestVerifyContractWrongContract(t *testing.T) {
+// tests if ValidateCode rejects an address with different bytecode
+func TestValidateWrongCode(t *testing.T) {
 	swap, clean := newTestSwap(t, ownerKey)
 	defer clean()
 
@@ -679,7 +679,7 @@ func TestVerifyContractWrongContract(t *testing.T) {
 	testBackend.Commit()
 
 	// since the bytecode is different this should throw an error
-	if err = swap.verifyContract(context.TODO(), addr); err != cswap.ErrNotASwapContract {
+	if err = cswap.ValidateCode(context.TODO(), swap.backend, addr); err != cswap.ErrNotASwapContract {
 		t.Fatalf("Contract verification verified wrong contract: %v", err)
 	}
 }

swarm.go

@@ -133,7 +133,7 @@ func NewSwarm(config *api.Config, mockStore *mock.NodeStore) (self *Swarm, err e
 			return nil, err
 		}
 		// create the accounting objects
-		self.swap = swap.New(swapStore, self.privateKey, self.config.Contract, self.backend)
+		self.swap = swap.New(swapStore, self.privateKey, self.backend)
 		// start anonymous metrics collection
 		self.accountingMetrics = protocols.SetupAccountingMetrics(10*time.Second, filepath.Join(config.Path, "metrics.db"))
 	}
@@ -374,11 +374,9 @@ func (s *Swarm) Start(srv *p2p.Server) error {
 	log.Info("Updated bzz local addr", "oaddr", fmt.Sprintf("%x", newaddr.OAddr), "uaddr", fmt.Sprintf("%s", newaddr.UAddr))
 
 	if s.config.SwapEnabled {
-		err := s.swap.Deploy(context.Background(), s.backend, s.config.Path)
-		if err != nil {
-			return fmt.Errorf("Unable to deploy swap contract: %v", err)
+		if err := s.swap.StartChequebook(s.config.Contract); err != nil {
+			return err
 		}
-		log.Info("SWAP contract deployed", "contract info", s.swap.DeploySuccess())
 	} else {
 		log.Info("SWAP disabled: no chequebook set")
 	}