Feature/mailserver registry smart contract (#1135)

* add verifier and test using simulated backend

* add ContractCaller

* commit simulated backend after deploy and after smart contract writes

* use bind.NewKeyedTransactor for all transactions in tests

* rename RegistryVerifier to Verifier

* initialize contract verifier if MailServerRegistryAddress config is set

* use contractAddress.Hash()

* refactoring

* use fmt.Sprintf to format contract address in logs

* fix test and lint warnings

* update Gopkg.lock

* update Gopkg.lock once more

Gopkg.lock

@@ -1025,6 +1025,8 @@
     "github.com/btcsuite/btcutil/base58",
     "github.com/ethereum/go-ethereum",
     "github.com/ethereum/go-ethereum/accounts",
+    "github.com/ethereum/go-ethereum/accounts/abi",
+    "github.com/ethereum/go-ethereum/accounts/abi/bind",
     "github.com/ethereum/go-ethereum/accounts/abi/bind/backends",
     "github.com/ethereum/go-ethereum/accounts/keystore",
     "github.com/ethereum/go-ethereum/common",

contracts/contract_caller.go

@@ -0,0 +1,67 @@
+package contracts
+
+import (
+	"context"
+	"math/big"
+
+	ethereum "github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+)
+
+type RPCClient interface {
+	CallContext(ctx context.Context, result interface{}, method string, args ...interface{}) error
+}
+
+type ContractCaller struct {
+	c RPCClient
+}
+
+func NewContractCaller(c RPCClient) *ContractCaller {
+	return &ContractCaller{
+		c: c,
+	}
+}
+
+// CodeAt returns the contract code of the given account.
+// The block number can be nil, in which case the code is taken from the latest known block.
+func (cc *ContractCaller) CodeAt(ctx context.Context, account common.Address, blockNumber *big.Int) ([]byte, error) {
+	var result hexutil.Bytes
+	err := cc.c.CallContext(ctx, &result, "eth_getCode", account, "latest")
+	return result, err
+}
+
+// CallContract executes a message call transaction, which is directly executed in the VM
+// of the node, but never mined into the blockchain.
+//
+// blockNumber selects the block height at which the call runs. It can be nil, in which
+// case the code is taken from the latest known block. Note that state from very old
+// blocks might not be available.
+func (cc *ContractCaller) CallContract(ctx context.Context, msg ethereum.CallMsg, blockNumber *big.Int) ([]byte, error) {
+	var hex hexutil.Bytes
+	err := cc.c.CallContext(ctx, &hex, "eth_call", toCallArg(msg), "latest")
+	if err != nil {
+		return nil, err
+	}
+	return hex, nil
+}
+
+func toCallArg(msg ethereum.CallMsg) interface{} {
+	arg := map[string]interface{}{
+		"from": msg.From,
+		"to":   msg.To,
+	}
+	if len(msg.Data) > 0 {
+		arg["data"] = hexutil.Bytes(msg.Data)
+	}
+	if msg.Value != nil {
+		arg["value"] = (*hexutil.Big)(msg.Value)
+	}
+	if msg.Gas != 0 {
+		arg["gas"] = hexutil.Uint64(msg.Gas)
+	}
+	if msg.GasPrice != nil {
+		arg["gasPrice"] = (*hexutil.Big)(msg.GasPrice)
+	}
+	return arg
+}

mailserver/registry/registry.go

@@ -0,0 +1,535 @@
+// Code generated - DO NOT EDIT.
+// This file is a generated binding and any manual changes will be lost.
+
+package registry
+
+import (
+	"strings"
+
+	ethereum "github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum/accounts/abi"
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/event"
+)
+
+// RegistryABI is the input ABI used to generate the binding from.
+const RegistryABI = "[{\"constant\":false,\"inputs\":[{\"name\":\"_newController\",\"type\":\"address\"}],\"name\":\"changeController\",\"outputs\":[],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":false,\"inputs\":[{\"name\":\"a\",\"type\":\"bytes\"}],\"name\":\"remove\",\"outputs\":[],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[{\"name\":\"a\",\"type\":\"bytes\"}],\"name\":\"exists\",\"outputs\":[{\"name\":\"\",\"type\":\"bool\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":false,\"inputs\":[{\"name\":\"a\",\"type\":\"bytes\"}],\"name\":\"add\",\"outputs\":[],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"controller\",\"outputs\":[{\"name\":\"\",\"type\":\"address\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"anonymous\":false,\"inputs\":[{\"indexed\":false,\"name\":\"a\",\"type\":\"bytes\"}],\"name\":\"MailServerAdded\",\"type\":\"event\"},{\"anonymous\":false,\"inputs\":[{\"indexed\":false,\"name\":\"a\",\"type\":\"bytes\"}],\"name\":\"MailServerRemoved\",\"type\":\"event\"}]"
+
+// RegistryBin is the compiled bytecode used for deploying new contracts.
+const RegistryBin = `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`
+
+// DeployRegistry deploys a new Ethereum contract, binding an instance of Registry to it.
+func DeployRegistry(auth *bind.TransactOpts, backend bind.ContractBackend) (common.Address, *types.Transaction, *Registry, error) {
+	parsed, err := abi.JSON(strings.NewReader(RegistryABI))
+	if err != nil {
+		return common.Address{}, nil, nil, err
+	}
+	address, tx, contract, err := bind.DeployContract(auth, parsed, common.FromHex(RegistryBin), backend)
+	if err != nil {
+		return common.Address{}, nil, nil, err
+	}
+	return address, tx, &Registry{RegistryCaller: RegistryCaller{contract: contract}, RegistryTransactor: RegistryTransactor{contract: contract}, RegistryFilterer: RegistryFilterer{contract: contract}}, nil
+}
+
+// Registry is an auto generated Go binding around an Ethereum contract.
+type Registry struct {
+	RegistryCaller     // Read-only binding to the contract
+	RegistryTransactor // Write-only binding to the contract
+	RegistryFilterer   // Log filterer for contract events
+}
+
+// RegistryCaller is an auto generated read-only Go binding around an Ethereum contract.
+type RegistryCaller struct {
+	contract *bind.BoundContract // Generic contract wrapper for the low level calls
+}
+
+// RegistryTransactor is an auto generated write-only Go binding around an Ethereum contract.
+type RegistryTransactor struct {
+	contract *bind.BoundContract // Generic contract wrapper for the low level calls
+}
+
+// RegistryFilterer is an auto generated log filtering Go binding around an Ethereum contract events.
+type RegistryFilterer struct {
+	contract *bind.BoundContract // Generic contract wrapper for the low level calls
+}
+
+// RegistrySession is an auto generated Go binding around an Ethereum contract,
+// with pre-set call and transact options.
+type RegistrySession struct {
+	Contract     *Registry         // Generic contract binding to set the session for
+	CallOpts     bind.CallOpts     // Call options to use throughout this session
+	TransactOpts bind.TransactOpts // Transaction auth options to use throughout this session
+}
+
+// RegistryCallerSession is an auto generated read-only Go binding around an Ethereum contract,
+// with pre-set call options.
+type RegistryCallerSession struct {
+	Contract *RegistryCaller // Generic contract caller binding to set the session for
+	CallOpts bind.CallOpts   // Call options to use throughout this session
+}
+
+// RegistryTransactorSession is an auto generated write-only Go binding around an Ethereum contract,
+// with pre-set transact options.
+type RegistryTransactorSession struct {
+	Contract     *RegistryTransactor // Generic contract transactor binding to set the session for
+	TransactOpts bind.TransactOpts   // Transaction auth options to use throughout this session
+}
+
+// RegistryRaw is an auto generated low-level Go binding around an Ethereum contract.
+type RegistryRaw struct {
+	Contract *Registry // Generic contract binding to access the raw methods on
+}
+
+// RegistryCallerRaw is an auto generated low-level read-only Go binding around an Ethereum contract.
+type RegistryCallerRaw struct {
+	Contract *RegistryCaller // Generic read-only contract binding to access the raw methods on
+}
+
+// RegistryTransactorRaw is an auto generated low-level write-only Go binding around an Ethereum contract.
+type RegistryTransactorRaw struct {
+	Contract *RegistryTransactor // Generic write-only contract binding to access the raw methods on
+}
+
+// NewRegistry creates a new instance of Registry, bound to a specific deployed contract.
+func NewRegistry(address common.Address, backend bind.ContractBackend) (*Registry, error) {
+	contract, err := bindRegistry(address, backend, backend, backend)
+	if err != nil {
+		return nil, err
+	}
+	return &Registry{RegistryCaller: RegistryCaller{contract: contract}, RegistryTransactor: RegistryTransactor{contract: contract}, RegistryFilterer: RegistryFilterer{contract: contract}}, nil
+}
+
+// NewRegistryCaller creates a new read-only instance of Registry, bound to a specific deployed contract.
+func NewRegistryCaller(address common.Address, caller bind.ContractCaller) (*RegistryCaller, error) {
+	contract, err := bindRegistry(address, caller, nil, nil)
+	if err != nil {
+		return nil, err
+	}
+	return &RegistryCaller{contract: contract}, nil
+}
+
+// NewRegistryTransactor creates a new write-only instance of Registry, bound to a specific deployed contract.
+func NewRegistryTransactor(address common.Address, transactor bind.ContractTransactor) (*RegistryTransactor, error) {
+	contract, err := bindRegistry(address, nil, transactor, nil)
+	if err != nil {
+		return nil, err
+	}
+	return &RegistryTransactor{contract: contract}, nil
+}
+
+// NewRegistryFilterer creates a new log filterer instance of Registry, bound to a specific deployed contract.
+func NewRegistryFilterer(address common.Address, filterer bind.ContractFilterer) (*RegistryFilterer, error) {
+	contract, err := bindRegistry(address, nil, nil, filterer)
+	if err != nil {
+		return nil, err
+	}
+	return &RegistryFilterer{contract: contract}, nil
+}
+
+// bindRegistry binds a generic wrapper to an already deployed contract.
+func bindRegistry(address common.Address, caller bind.ContractCaller, transactor bind.ContractTransactor, filterer bind.ContractFilterer) (*bind.BoundContract, error) {
+	parsed, err := abi.JSON(strings.NewReader(RegistryABI))
+	if err != nil {
+		return nil, err
+	}
+	return bind.NewBoundContract(address, parsed, caller, transactor, filterer), nil
+}
+
+// Call invokes the (constant) contract method with params as input values and
+// sets the output to result. The result type might be a single field for simple
+// returns, a slice of interfaces for anonymous returns and a struct for named
+// returns.
+func (_Registry *RegistryRaw) Call(opts *bind.CallOpts, result interface{}, method string, params ...interface{}) error {
+	return _Registry.Contract.RegistryCaller.contract.Call(opts, result, method, params...)
+}
+
+// Transfer initiates a plain transaction to move funds to the contract, calling
+// its default method if one is available.
+func (_Registry *RegistryRaw) Transfer(opts *bind.TransactOpts) (*types.Transaction, error) {
+	return _Registry.Contract.RegistryTransactor.contract.Transfer(opts)
+}
+
+// Transact invokes the (paid) contract method with params as input values.
+func (_Registry *RegistryRaw) Transact(opts *bind.TransactOpts, method string, params ...interface{}) (*types.Transaction, error) {
+	return _Registry.Contract.RegistryTransactor.contract.Transact(opts, method, params...)
+}
+
+// Call invokes the (constant) contract method with params as input values and
+// sets the output to result. The result type might be a single field for simple
+// returns, a slice of interfaces for anonymous returns and a struct for named
+// returns.
+func (_Registry *RegistryCallerRaw) Call(opts *bind.CallOpts, result interface{}, method string, params ...interface{}) error {
+	return _Registry.Contract.contract.Call(opts, result, method, params...)
+}
+
+// Transfer initiates a plain transaction to move funds to the contract, calling
+// its default method if one is available.
+func (_Registry *RegistryTransactorRaw) Transfer(opts *bind.TransactOpts) (*types.Transaction, error) {
+	return _Registry.Contract.contract.Transfer(opts)
+}
+
+// Transact invokes the (paid) contract method with params as input values.
+func (_Registry *RegistryTransactorRaw) Transact(opts *bind.TransactOpts, method string, params ...interface{}) (*types.Transaction, error) {
+	return _Registry.Contract.contract.Transact(opts, method, params...)
+}
+
+// Controller is a free data retrieval call binding the contract method 0xf77c4791.
+//
+// Solidity: function controller() constant returns(address)
+func (_Registry *RegistryCaller) Controller(opts *bind.CallOpts) (common.Address, error) {
+	var (
+		ret0 = new(common.Address)
+	)
+	out := ret0
+	err := _Registry.contract.Call(opts, out, "controller")
+	return *ret0, err
+}
+
+// Controller is a free data retrieval call binding the contract method 0xf77c4791.
+//
+// Solidity: function controller() constant returns(address)
+func (_Registry *RegistrySession) Controller() (common.Address, error) {
+	return _Registry.Contract.Controller(&_Registry.CallOpts)
+}
+
+// Controller is a free data retrieval call binding the contract method 0xf77c4791.
+//
+// Solidity: function controller() constant returns(address)
+func (_Registry *RegistryCallerSession) Controller() (common.Address, error) {
+	return _Registry.Contract.Controller(&_Registry.CallOpts)
+}
+
+// Exists is a free data retrieval call binding the contract method 0x79fc09a2.
+//
+// Solidity: function exists(a bytes) constant returns(bool)
+func (_Registry *RegistryCaller) Exists(opts *bind.CallOpts, a []byte) (bool, error) {
+	var (
+		ret0 = new(bool)
+	)
+	out := ret0
+	err := _Registry.contract.Call(opts, out, "exists", a)
+	return *ret0, err
+}
+
+// Exists is a free data retrieval call binding the contract method 0x79fc09a2.
+//
+// Solidity: function exists(a bytes) constant returns(bool)
+func (_Registry *RegistrySession) Exists(a []byte) (bool, error) {
+	return _Registry.Contract.Exists(&_Registry.CallOpts, a)
+}
+
+// Exists is a free data retrieval call binding the contract method 0x79fc09a2.
+//
+// Solidity: function exists(a bytes) constant returns(bool)
+func (_Registry *RegistryCallerSession) Exists(a []byte) (bool, error) {
+	return _Registry.Contract.Exists(&_Registry.CallOpts, a)
+}
+
+// Add is a paid mutator transaction binding the contract method 0xba658111.
+//
+// Solidity: function add(a bytes) returns()
+func (_Registry *RegistryTransactor) Add(opts *bind.TransactOpts, a []byte) (*types.Transaction, error) {
+	return _Registry.contract.Transact(opts, "add", a)
+}
+
+// Add is a paid mutator transaction binding the contract method 0xba658111.
+//
+// Solidity: function add(a bytes) returns()
+func (_Registry *RegistrySession) Add(a []byte) (*types.Transaction, error) {
+	return _Registry.Contract.Add(&_Registry.TransactOpts, a)
+}
+
+// Add is a paid mutator transaction binding the contract method 0xba658111.
+//
+// Solidity: function add(a bytes) returns()
+func (_Registry *RegistryTransactorSession) Add(a []byte) (*types.Transaction, error) {
+	return _Registry.Contract.Add(&_Registry.TransactOpts, a)
+}
+
+// ChangeController is a paid mutator transaction binding the contract method 0x3cebb823.
+//
+// Solidity: function changeController(_newController address) returns()
+func (_Registry *RegistryTransactor) ChangeController(opts *bind.TransactOpts, _newController common.Address) (*types.Transaction, error) {
+	return _Registry.contract.Transact(opts, "changeController", _newController)
+}
+
+// ChangeController is a paid mutator transaction binding the contract method 0x3cebb823.
+//
+// Solidity: function changeController(_newController address) returns()
+func (_Registry *RegistrySession) ChangeController(_newController common.Address) (*types.Transaction, error) {
+	return _Registry.Contract.ChangeController(&_Registry.TransactOpts, _newController)
+}
+
+// ChangeController is a paid mutator transaction binding the contract method 0x3cebb823.
+//
+// Solidity: function changeController(_newController address) returns()
+func (_Registry *RegistryTransactorSession) ChangeController(_newController common.Address) (*types.Transaction, error) {
+	return _Registry.Contract.ChangeController(&_Registry.TransactOpts, _newController)
+}
+
+// Remove is a paid mutator transaction binding the contract method 0x58edef4c.
+//
+// Solidity: function remove(a bytes) returns()
+func (_Registry *RegistryTransactor) Remove(opts *bind.TransactOpts, a []byte) (*types.Transaction, error) {
+	return _Registry.contract.Transact(opts, "remove", a)
+}
+
+// Remove is a paid mutator transaction binding the contract method 0x58edef4c.
+//
+// Solidity: function remove(a bytes) returns()
+func (_Registry *RegistrySession) Remove(a []byte) (*types.Transaction, error) {
+	return _Registry.Contract.Remove(&_Registry.TransactOpts, a)
+}
+
+// Remove is a paid mutator transaction binding the contract method 0x58edef4c.
+//
+// Solidity: function remove(a bytes) returns()
+func (_Registry *RegistryTransactorSession) Remove(a []byte) (*types.Transaction, error) {
+	return _Registry.Contract.Remove(&_Registry.TransactOpts, a)
+}
+
+// RegistryMailServerAddedIterator is returned from FilterMailServerAdded and is used to iterate over the raw logs and unpacked data for MailServerAdded events raised by the Registry contract.
+type RegistryMailServerAddedIterator struct {
+	Event *RegistryMailServerAdded // Event containing the contract specifics and raw log
+
+	contract *bind.BoundContract // Generic contract to use for unpacking event data
+	event    string              // Event name to use for unpacking event data
+
+	logs chan types.Log        // Log channel receiving the found contract events
+	sub  ethereum.Subscription // Subscription for errors, completion and termination
+	done bool                  // Whether the subscription completed delivering logs
+	fail error                 // Occurred error to stop iteration
+}
+
+// Next advances the iterator to the subsequent event, returning whether there
+// are any more events found. In case of a retrieval or parsing error, false is
+// returned and Error() can be queried for the exact failure.
+func (it *RegistryMailServerAddedIterator) Next() bool {
+	// If the iterator failed, stop iterating
+	if it.fail != nil {
+		return false
+	}
+	// If the iterator completed, deliver directly whatever's available
+	if it.done {
+		select {
+		case log := <-it.logs:
+			it.Event = new(RegistryMailServerAdded)
+			if err := it.contract.UnpackLog(it.Event, it.event, log); err != nil {
+				it.fail = err
+				return false
+			}
+			it.Event.Raw = log
+			return true
+
+		default:
+			return false
+		}
+	}
+	// Iterator still in progress, wait for either a data or an error event
+	select {
+	case log := <-it.logs:
+		it.Event = new(RegistryMailServerAdded)
+		if err := it.contract.UnpackLog(it.Event, it.event, log); err != nil {
+			it.fail = err
+			return false
+		}
+		it.Event.Raw = log
+		return true
+
+	case err := <-it.sub.Err():
+		it.done = true
+		it.fail = err
+		return it.Next()
+	}
+}
+
+// Error returns any retrieval or parsing error occurred during filtering.
+func (it *RegistryMailServerAddedIterator) Error() error {
+	return it.fail
+}
+
+// Close terminates the iteration process, releasing any pending underlying
+// resources.
+func (it *RegistryMailServerAddedIterator) Close() error {
+	it.sub.Unsubscribe()
+	return nil
+}
+
+// RegistryMailServerAdded represents a MailServerAdded event raised by the Registry contract.
+type RegistryMailServerAdded struct {
+	A   []byte
+	Raw types.Log // Blockchain specific contextual infos
+}
+
+// FilterMailServerAdded is a free log retrieval operation binding the contract event 0xcb379cb5890ec9889055734e1561cdc353a342d46d8d650c8c3a8d66383c29cd.
+//
+// Solidity: e MailServerAdded(a bytes)
+func (_Registry *RegistryFilterer) FilterMailServerAdded(opts *bind.FilterOpts) (*RegistryMailServerAddedIterator, error) {
+
+	logs, sub, err := _Registry.contract.FilterLogs(opts, "MailServerAdded")
+	if err != nil {
+		return nil, err
+	}
+	return &RegistryMailServerAddedIterator{contract: _Registry.contract, event: "MailServerAdded", logs: logs, sub: sub}, nil
+}
+
+// WatchMailServerAdded is a free log subscription operation binding the contract event 0xcb379cb5890ec9889055734e1561cdc353a342d46d8d650c8c3a8d66383c29cd.
+//
+// Solidity: e MailServerAdded(a bytes)
+func (_Registry *RegistryFilterer) WatchMailServerAdded(opts *bind.WatchOpts, sink chan<- *RegistryMailServerAdded) (event.Subscription, error) {
+
+	logs, sub, err := _Registry.contract.WatchLogs(opts, "MailServerAdded")
+	if err != nil {
+		return nil, err
+	}
+	return event.NewSubscription(func(quit <-chan struct{}) error {
+		defer sub.Unsubscribe()
+		for {
+			select {
+			case log := <-logs:
+				// New log arrived, parse the event and forward to the user
+				event := new(RegistryMailServerAdded)
+				if err := _Registry.contract.UnpackLog(event, "MailServerAdded", log); err != nil {
+					return err
+				}
+				event.Raw = log
+
+				select {
+				case sink <- event:
+				case err := <-sub.Err():
+					return err
+				case <-quit:
+					return nil
+				}
+			case err := <-sub.Err():
+				return err
+			case <-quit:
+				return nil
+			}
+		}
+	}), nil
+}
+
+// RegistryMailServerRemovedIterator is returned from FilterMailServerRemoved and is used to iterate over the raw logs and unpacked data for MailServerRemoved events raised by the Registry contract.
+type RegistryMailServerRemovedIterator struct {
+	Event *RegistryMailServerRemoved // Event containing the contract specifics and raw log
+
+	contract *bind.BoundContract // Generic contract to use for unpacking event data
+	event    string              // Event name to use for unpacking event data
+
+	logs chan types.Log        // Log channel receiving the found contract events
+	sub  ethereum.Subscription // Subscription for errors, completion and termination
+	done bool                  // Whether the subscription completed delivering logs
+	fail error                 // Occurred error to stop iteration
+}
+
+// Next advances the iterator to the subsequent event, returning whether there
+// are any more events found. In case of a retrieval or parsing error, false is
+// returned and Error() can be queried for the exact failure.
+func (it *RegistryMailServerRemovedIterator) Next() bool {
+	// If the iterator failed, stop iterating
+	if it.fail != nil {
+		return false
+	}
+	// If the iterator completed, deliver directly whatever's available
+	if it.done {
+		select {
+		case log := <-it.logs:
+			it.Event = new(RegistryMailServerRemoved)
+			if err := it.contract.UnpackLog(it.Event, it.event, log); err != nil {
+				it.fail = err
+				return false
+			}
+			it.Event.Raw = log
+			return true
+
+		default:
+			return false
+		}
+	}
+	// Iterator still in progress, wait for either a data or an error event
+	select {
+	case log := <-it.logs:
+		it.Event = new(RegistryMailServerRemoved)
+		if err := it.contract.UnpackLog(it.Event, it.event, log); err != nil {
+			it.fail = err
+			return false
+		}
+		it.Event.Raw = log
+		return true
+
+	case err := <-it.sub.Err():
+		it.done = true
+		it.fail = err
+		return it.Next()
+	}
+}
+
+// Error returns any retrieval or parsing error occurred during filtering.
+func (it *RegistryMailServerRemovedIterator) Error() error {
+	return it.fail
+}
+
+// Close terminates the iteration process, releasing any pending underlying
+// resources.
+func (it *RegistryMailServerRemovedIterator) Close() error {
+	it.sub.Unsubscribe()
+	return nil
+}
+
+// RegistryMailServerRemoved represents a MailServerRemoved event raised by the Registry contract.
+type RegistryMailServerRemoved struct {
+	A   []byte
+	Raw types.Log // Blockchain specific contextual infos
+}
+
+// FilterMailServerRemoved is a free log retrieval operation binding the contract event 0x44e7d85a87eeb950b8bdc144d44b0b474be610d1953607251a0130edc10a222b.
+//
+// Solidity: e MailServerRemoved(a bytes)
+func (_Registry *RegistryFilterer) FilterMailServerRemoved(opts *bind.FilterOpts) (*RegistryMailServerRemovedIterator, error) {
+
+	logs, sub, err := _Registry.contract.FilterLogs(opts, "MailServerRemoved")
+	if err != nil {
+		return nil, err
+	}
+	return &RegistryMailServerRemovedIterator{contract: _Registry.contract, event: "MailServerRemoved", logs: logs, sub: sub}, nil
+}
+
+// WatchMailServerRemoved is a free log subscription operation binding the contract event 0x44e7d85a87eeb950b8bdc144d44b0b474be610d1953607251a0130edc10a222b.
+//
+// Solidity: e MailServerRemoved(a bytes)
+func (_Registry *RegistryFilterer) WatchMailServerRemoved(opts *bind.WatchOpts, sink chan<- *RegistryMailServerRemoved) (event.Subscription, error) {
+
+	logs, sub, err := _Registry.contract.WatchLogs(opts, "MailServerRemoved")
+	if err != nil {
+		return nil, err
+	}
+	return event.NewSubscription(func(quit <-chan struct{}) error {
+		defer sub.Unsubscribe()
+		for {
+			select {
+			case log := <-logs:
+				// New log arrived, parse the event and forward to the user
+				event := new(RegistryMailServerRemoved)
+				if err := _Registry.contract.UnpackLog(event, "MailServerRemoved", log); err != nil {
+					return err
+				}
+				event.Raw = log
+
+				select {
+				case sink <- event:
+				case err := <-sub.Err():
+					return err
+				case <-quit:
+					return nil
+				}
+			case err := <-sub.Err():
+				return err
+			case <-quit:
+				return nil
+			}
+		}
+	}), nil
+}

mailserver/registry/verifier.go

@@ -0,0 +1,44 @@
+package registry
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/p2p/discover"
+)
+
+var logger = log.New("package", "mailserver/registry")
+
+// Verifier verifies nodes based on a smart contract.
+type Verifier struct {
+	rc *RegistryCaller
+}
+
+// NewVerifier returns a new Verifier instance.
+func NewVerifier(contractCaller bind.ContractCaller, contractAddress common.Address) (*Verifier, error) {
+	logger.Debug("initializing mailserver registry verifier", "address", fmt.Sprintf("0x%x", contractAddress))
+	rc, err := NewRegistryCaller(contractAddress, contractCaller)
+	if err != nil {
+		logger.Debug("error initializing mailserver registry verifier", "address", fmt.Sprintf("0x%x", contractAddress))
+		return nil, err
+	}
+
+	return &Verifier{
+		rc: rc,
+	}, nil
+}
+
+// VerifyNode checks if a given node is trusted using a smart contract.
+func (v *Verifier) VerifyNode(ctx context.Context, nodeID discover.NodeID) bool {
+	res, err := v.rc.Exists(&bind.CallOpts{Context: ctx}, nodeID.Bytes())
+	logger.Debug("verifying node", "id", nodeID, "verified", res)
+	if err != nil {
+		logger.Error("error verifying node", "id", nodeID, "error", err)
+		return false
+	}
+
+	return res
+}

mailserver/registry/verifier_test.go

@@ -0,0 +1,86 @@
+package registry
+
+import (
+	"context"
+	"crypto/ecdsa"
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/accounts/abi/bind/backends"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/p2p/discover"
+	"github.com/stretchr/testify/suite"
+)
+
+type VerifierTestSuite struct {
+	suite.Suite
+	backend         *backends.SimulatedBackend
+	privKey         *ecdsa.PrivateKey
+	from            common.Address
+	contractAddress common.Address
+	registry        *Registry
+	verifier        *Verifier
+}
+
+func TestVerifierTestSuite(t *testing.T) {
+	suite.Run(t, &VerifierTestSuite{})
+}
+
+func (s *VerifierTestSuite) SetupTest() {
+	s.setupAccount()
+	s.setupBackendAndContract()
+
+	var err error
+	s.verifier, err = NewVerifier(s.backend, s.contractAddress)
+	s.Require().NoError(err)
+}
+
+func (s *VerifierTestSuite) setupBackendAndContract() {
+	var err error
+
+	auth := bind.NewKeyedTransactor(s.privKey)
+	alloc := make(core.GenesisAlloc)
+	alloc[auth.From] = core.GenesisAccount{Balance: big.NewInt(133700000)}
+	s.backend = backends.NewSimulatedBackend(alloc)
+
+	s.contractAddress, _, s.registry, err = DeployRegistry(auth, s.backend)
+	s.Require().NoError(err)
+	s.backend.Commit()
+}
+
+func (s *VerifierTestSuite) setupAccount() {
+	var err error
+
+	s.privKey, err = crypto.GenerateKey()
+	s.Require().NoError(err)
+
+	s.from = crypto.PubkeyToAddress(s.privKey.PublicKey)
+}
+
+func (s *VerifierTestSuite) add(nodeID discover.NodeID) {
+	auth := bind.NewKeyedTransactor(s.privKey)
+	_, err := s.registry.Add(auth, nodeID[:])
+	s.Require().NoError(err)
+	s.backend.Commit()
+}
+
+func (s *VerifierTestSuite) generateNodeID() discover.NodeID {
+	k, err := crypto.GenerateKey()
+	s.Require().NoError(err)
+
+	return discover.PubkeyID(&k.PublicKey)
+}
+
+func (s *VerifierTestSuite) TestVerifyNode() {
+	id := s.generateNodeID()
+	res := s.verifier.VerifyNode(context.Background(), id)
+	s.Require().False(res)
+
+	s.add(id)
+
+	res = s.verifier.VerifyNode(context.Background(), id)
+	s.Require().True(res)
+}

node/status_node.go

@@ -251,6 +251,9 @@ func (n *StatusNode) startDiscovery() error {
 	// TODO(dshulyak) consider adding a flag to define this behaviour
 	options.AllowStop = len(n.config.RegisterTopics) == 0
 	options.TrustedMailServers = parseNodesToNodeID(n.config.ClusterConfig.TrustedMailServers)
+
+	options.MailServerRegistryAddress = n.config.MailServerRegistryAddress
+
 	n.peerPool = peers.NewPeerPool(
 		n.discovery,
 		n.config.RequireTopics,
@@ -263,7 +266,7 @@ func (n *StatusNode) startDiscovery() error {
 	if err := n.register.Start(); err != nil {
 		return err
 	}
-	return n.peerPool.Start(n.gethNode.Server())
+	return n.peerPool.Start(n.gethNode.Server(), n.rpcClient)
 }
 
 // Stop will stop current StatusNode. A stopped node cannot be resumed.
@@ -565,8 +568,8 @@ func (n *StatusNode) AccountKeyStore() (*keystore.KeyStore, error) {
 
 // RPCClient exposes reference to RPC client connected to the running node.
 func (n *StatusNode) RPCClient() *rpc.Client {
-	n.mu.Lock()
+	n.mu.RLock()
-	defer n.mu.Unlock()
+	defer n.mu.RUnlock()
 	return n.rpcClient
 }
 

params/config.go

@@ -357,6 +357,9 @@ type NodeConfig struct {
 
 	// DebugAPIEnabled enables debug api
 	DebugAPIEnabled bool
+
+	// MailServerRegistryAddress is the MailServerRegistry contract address
+	MailServerRegistryAddress string
 }
 
 // NewNodeConfig creates new node configuration object

peers/peerpool.go

@@ -5,6 +5,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/mclock"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/log"
@@ -12,7 +13,9 @@ import (
 	"github.com/ethereum/go-ethereum/p2p/discover"
 	"github.com/ethereum/go-ethereum/p2p/discv5"
 
+	"github.com/status-im/status-go/contracts"
 	"github.com/status-im/status-go/discovery"
+	"github.com/status-im/status-go/mailserver/registry"
 	"github.com/status-im/status-go/params"
 	"github.com/status-im/status-go/peers/verifier"
 	"github.com/status-im/status-go/signal"
@@ -56,6 +59,8 @@ type Options struct {
 	TopicStopSearchDelay time.Duration
 	// TrustedMailServers is a list of trusted nodes.
 	TrustedMailServers []discover.NodeID
+	// MailServerRegistryAddress is the MailServerRegistry contract address
+	MailServerRegistryAddress string
 }
 
 // NewDefaultOptions returns a struct with default Options.
@@ -115,7 +120,7 @@ func (p *PeerPool) setDiscoveryTimeout() {
 }
 
 // Start creates topic pool for each topic in config and subscribes to server events.
-func (p *PeerPool) Start(server *p2p.Server) error {
+func (p *PeerPool) Start(server *p2p.Server, rpcClient contracts.RPCClient) error {
 	if !p.discovery.Running() {
 		return ErrDiscv5NotRunning
 	}
@@ -143,7 +148,11 @@ func (p *PeerPool) Start(server *p2p.Server) error {
 		var topicPool TopicPoolInterface
 		t := newTopicPool(p.discovery, topic, limits, p.opts.SlowSync, p.opts.FastSync, p.cache)
 		if topic == MailServerDiscoveryTopic {
-			topicPool = newCacheOnlyTopicPool(t, verifier.NewLocalVerifier(p.opts.TrustedMailServers))
+			v, err := p.initVerifier(rpcClient)
+			if err != nil {
+				return err
+			}
+			topicPool = newCacheOnlyTopicPool(t, v)
 		} else {
 			topicPool = t
 		}
@@ -159,6 +168,16 @@ func (p *PeerPool) Start(server *p2p.Server) error {
 	return nil
 }
 
+func (p *PeerPool) initVerifier(rpcClient contracts.RPCClient) (v Verifier, err error) {
+	if addr := p.opts.MailServerRegistryAddress; addr != "" {
+		caller := contracts.NewContractCaller(rpcClient)
+		addrBytes := common.FromHex(addr)
+		return registry.NewVerifier(caller, common.BytesToAddress(addrBytes))
+	}
+
+	return verifier.NewLocalVerifier(p.opts.TrustedMailServers), nil
+}
+
 func (p *PeerPool) startDiscovery() error {
 	if p.discovery.Running() {
 		return nil

peers/peerpool_test.go

@@ -162,13 +162,13 @@ func (s *PeerPoolSimulationSuite) TestPeerPoolCacheEthV5() {
 	config := map[discv5.Topic]params.Limits{
 		topic: params.NewLimits(1, 1),
 	}
-	peerPoolOpts := &Options{100 * time.Millisecond, 100 * time.Millisecond, 0, true, 100 * time.Millisecond, nil}
+	peerPoolOpts := &Options{100 * time.Millisecond, 100 * time.Millisecond, 0, true, 100 * time.Millisecond, nil, ""}
 	cache, err := newInMemoryCache()
 	s.Require().NoError(err)
 	peerPool := NewPeerPool(s.discovery[1], config, cache, peerPoolOpts)
 
 	// start peer pool
-	s.Require().NoError(peerPool.Start(s.peers[1]))
+	s.Require().NoError(peerPool.Start(s.peers[1], nil))
 	defer peerPool.Stop()
 
 	// check if cache is passed to topic pools
@@ -220,7 +220,7 @@ func (s *PeerPoolSimulationSuite) singleTopicDiscoveryWithFailover() {
 	config := map[discv5.Topic]params.Limits{
 		topic: params.NewLimits(1, 1), // limits are chosen for simplicity of the simulation
 	}
-	peerPoolOpts := &Options{100 * time.Millisecond, 100 * time.Millisecond, 0, true, 0, nil}
+	peerPoolOpts := &Options{100 * time.Millisecond, 100 * time.Millisecond, 0, true, 0, nil, ""}
 	cache, err := newInMemoryCache()
 	s.Require().NoError(err)
 	peerPool := NewPeerPool(s.discovery[1], config, cache, peerPoolOpts)
@@ -235,7 +235,7 @@ func (s *PeerPoolSimulationSuite) singleTopicDiscoveryWithFailover() {
 	defer subscription.Unsubscribe()
 
 	// start the peer pool
-	s.Require().NoError(peerPool.Start(s.peers[1]))
+	s.Require().NoError(peerPool.Start(s.peers[1], nil))
 	defer peerPool.Stop()
 	s.Equal(signal.EventDiscoveryStarted, s.getPoolEvent(poolEvents))
 
@@ -302,9 +302,9 @@ func TestPeerPoolMaxPeersOverflow(t *testing.T) {
 	defer func() { assert.NoError(t, discovery.Stop()) }()
 	require.True(t, discovery.Running())
 
-	poolOpts := &Options{DefaultFastSync, DefaultSlowSync, 0, true, 100 * time.Millisecond, nil}
+	poolOpts := &Options{DefaultFastSync, DefaultSlowSync, 0, true, 100 * time.Millisecond, nil, ""}
 	pool := NewPeerPool(discovery, nil, nil, poolOpts)
-	require.NoError(t, pool.Start(peer))
+	require.NoError(t, pool.Start(peer, nil))
 	require.Equal(t, signal.EventDiscoveryStarted, <-signals)
 	// without config, it will stop the discovery because all topic pools are satisfied
 	pool.events <- &p2p.PeerEvent{Type: p2p.PeerEventTypeAdd}
@@ -355,9 +355,9 @@ func TestPeerPoolDiscV5Timeout(t *testing.T) {
 	require.True(t, discovery.Running())
 
 	// start PeerPool
-	poolOpts := &Options{DefaultFastSync, DefaultSlowSync, time.Millisecond * 100, true, 100 * time.Millisecond, nil}
+	poolOpts := &Options{DefaultFastSync, DefaultSlowSync, time.Millisecond * 100, true, 100 * time.Millisecond, nil, ""}
 	pool := NewPeerPool(discovery, nil, nil, poolOpts)
-	require.NoError(t, pool.Start(server))
+	require.NoError(t, pool.Start(server, nil))
 	require.Equal(t, signal.EventDiscoveryStarted, <-signals)
 
 	// timeout after finding no peers
@@ -402,9 +402,9 @@ func TestPeerPoolNotAllowedStopping(t *testing.T) {
 	require.True(t, discovery.Running())
 
 	// start PeerPool
-	poolOpts := &Options{DefaultFastSync, DefaultSlowSync, time.Millisecond * 100, false, 100 * time.Millisecond, nil}
+	poolOpts := &Options{DefaultFastSync, DefaultSlowSync, time.Millisecond * 100, false, 100 * time.Millisecond, nil, ""}
 	pool := NewPeerPool(discovery, nil, nil, poolOpts)
-	require.NoError(t, pool.Start(server))
+	require.NoError(t, pool.Start(server, nil))
 
 	// wait 2x timeout duration
 	<-time.After(pool.opts.DiscServerTimeout * 2)
@@ -419,13 +419,13 @@ func (s *PeerPoolSimulationSuite) TestUpdateTopicLimits() {
 	config := map[discv5.Topic]params.Limits{
 		topic: params.NewLimits(1, 1),
 	}
-	peerPoolOpts := &Options{100 * time.Millisecond, 100 * time.Millisecond, 0, true, 100 * time.Millisecond, nil}
+	peerPoolOpts := &Options{100 * time.Millisecond, 100 * time.Millisecond, 0, true, 100 * time.Millisecond, nil, ""}
 	cache, err := newInMemoryCache()
 	s.Require().NoError(err)
 	peerPool := NewPeerPool(s.discovery[1], config, cache, peerPoolOpts)
 
 	// start peer pool
-	s.Require().NoError(peerPool.Start(s.peers[1]))
+	s.Require().NoError(peerPool.Start(s.peers[1], nil))
 	defer peerPool.Stop()
 
 	for _, topicPool := range peerPool.topics {
@@ -495,9 +495,10 @@ func (s *PeerPoolSimulationSuite) TestMailServerPeersDiscovery() {
 		true,
 		100 * time.Millisecond,
 		[]discover.NodeID{s.peers[0].Self().ID},
+		"",
 	}
 	peerPool := NewPeerPool(s.discovery[1], config, cache, peerPoolOpts)
-	s.Require().NoError(peerPool.Start(s.peers[1]))
+	s.Require().NoError(peerPool.Start(s.peers[1], nil))
 	defer peerPool.Stop()
 
 	// wait for and verify the mail server peer