Swarm accounting (#18050)

* swarm: completed 1st phase of swap accounting

* swarm: swap accounting for swarm with p2p accounting

* swarm/swap: addressed PR comments

* swarm/swap: ignore ErrNotFound on stateStore.Get()

* swarm/swap: GetPeerBalance test; add TODO for chequebook API check

* swarm/network/stream: fix NewRegistry calls with new arguments

* swarm/swap: address @justelad's PR comments

2 files changed, 277 insertions, 0 deletions

diff --git a/swarm/swap/swap.go b/swarm/swap/swap.go
new file mode 100644
index 000000000..137eb141d
--- /dev/null
+++ b/swarm/swap/swap.go
@@ -0,0 +1,93 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package swap
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"sync"
+
+	"github.com/ethereum/go-ethereum/p2p/enode"
+	"github.com/ethereum/go-ethereum/p2p/protocols"
+	"github.com/ethereum/go-ethereum/swarm/log"
+	"github.com/ethereum/go-ethereum/swarm/state"
+)
+
+// SwAP Swarm Accounting Protocol
+// a peer to peer micropayment system
+// A node maintains an individual balance with every peer
+// Only messages which have a price will be accounted for
+type Swap struct {
+	stateStore state.Store        //stateStore is needed in order to keep balances across sessions
+	lock       sync.RWMutex       //lock the balances
+	balances   map[enode.ID]int64 //map of balances for each peer
+}
+
+// New - swap constructor
+func New(stateStore state.Store) (swap *Swap) {
+	swap = &Swap{
+		stateStore: stateStore,
+		balances:   make(map[enode.ID]int64),
+	}
+	return
+}
+
+//Swap implements the protocols.Balance interface
+//Add is the (sole) accounting function
+func (s *Swap) Add(amount int64, peer *protocols.Peer) (err error) {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	//load existing balances from the state store
+	err = s.loadState(peer)
+	if err != nil && err != state.ErrNotFound {
+		return
+	}
+	//adjust the balance
+	//if amount is negative, it will decrease, otherwise increase
+	s.balances[peer.ID()] += amount
+	//save the new balance to the state store
+	peerBalance := s.balances[peer.ID()]
+	err = s.stateStore.Put(peer.ID().String(), &peerBalance)
+
+	log.Debug(fmt.Sprintf("balance for peer %s: %s", peer.ID().String(), strconv.FormatInt(peerBalance, 10)))
+	return err
+}
+
+//GetPeerBalance returns the balance for a given peer
+func (swap *Swap) GetPeerBalance(peer enode.ID) (int64, error) {
+	swap.lock.RLock()
+	defer swap.lock.RUnlock()
+	if p, ok := swap.balances[peer]; ok {
+		return p, nil
+	}
+	return 0, errors.New("Peer not found")
+}
+
+//load balances from the state store (persisted)
+func (s *Swap) loadState(peer *protocols.Peer) (err error) {
+	var peerBalance int64
+	peerID := peer.ID()
+	//only load if the current instance doesn't already have this peer's
+	//balance in memory
+	if _, ok := s.balances[peerID]; !ok {
+		err = s.stateStore.Get(peerID.String(), &peerBalance)
+		s.balances[peerID] = peerBalance
+	}
+	return
+}
diff --git a/swarm/swap/swap_test.go b/swarm/swap/swap_test.go
new file mode 100644
index 000000000..f2e3ba168
--- /dev/null
+++ b/swarm/swap/swap_test.go
@@ -0,0 +1,184 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package swap
+
+import (
+	"flag"
+	"fmt"
+	"io/ioutil"
+	mrand "math/rand"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/p2p"
+	"github.com/ethereum/go-ethereum/p2p/protocols"
+	"github.com/ethereum/go-ethereum/p2p/simulations/adapters"
+	"github.com/ethereum/go-ethereum/swarm/state"
+	colorable "github.com/mattn/go-colorable"
+)
+
+var (
+	loglevel = flag.Int("loglevel", 2, "verbosity of logs")
+)
+
+func init() {
+	flag.Parse()
+	mrand.Seed(time.Now().UnixNano())
+
+	log.PrintOrigins(true)
+	log.Root().SetHandler(log.LvlFilterHandler(log.Lvl(*loglevel), log.StreamHandler(colorable.NewColorableStderr(), log.TerminalFormat(true))))
+}
+
+//Test getting a peer's balance
+func TestGetPeerBalance(t *testing.T) {
+	//create a test swap account
+	swap, testDir := createTestSwap(t)
+	defer os.RemoveAll(testDir)
+
+	//test for correct value
+	testPeer := newDummyPeer()
+	swap.balances[testPeer.ID()] = 888
+	b, err := swap.GetPeerBalance(testPeer.ID())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if b != 888 {
+		t.Fatalf("Expected peer's balance to be %d, but is %d", 888, b)
+	}
+
+	//test for inexistent node
+	id := adapters.RandomNodeConfig().ID
+	_, err = swap.GetPeerBalance(id)
+	if err == nil {
+		t.Fatal("Expected call to fail, but it didn't!")
+	}
+	if err.Error() != "Peer not found" {
+		t.Fatalf("Expected test to fail with %s, but is %s", "Peer not found", err.Error())
+	}
+}
+
+//Test that repeated bookings do correct accounting
+func TestRepeatedBookings(t *testing.T) {
+	//create a test swap account
+	swap, testDir := createTestSwap(t)
+	defer os.RemoveAll(testDir)
+
+	testPeer := newDummyPeer()
+	amount := mrand.Intn(100)
+	cnt := 1 + mrand.Intn(10)
+	for i := 0; i < cnt; i++ {
+		swap.Add(int64(amount), testPeer.Peer)
+	}
+	expectedBalance := int64(cnt * amount)
+	realBalance := swap.balances[testPeer.ID()]
+	if expectedBalance != realBalance {
+		t.Fatal(fmt.Sprintf("After %d credits of %d, expected balance to be: %d, but is: %d", cnt, amount, expectedBalance, realBalance))
+	}
+
+	testPeer2 := newDummyPeer()
+	amount = mrand.Intn(100)
+	cnt = 1 + mrand.Intn(10)
+	for i := 0; i < cnt; i++ {
+		swap.Add(0-int64(amount), testPeer2.Peer)
+	}
+	expectedBalance = int64(0 - (cnt * amount))
+	realBalance = swap.balances[testPeer2.ID()]
+	if expectedBalance != realBalance {
+		t.Fatal(fmt.Sprintf("After %d debits of %d, expected balance to be: %d, but is: %d", cnt, amount, expectedBalance, realBalance))
+	}
+
+	//mixed debits and credits
+	amount1 := mrand.Intn(100)
+	amount2 := mrand.Intn(55)
+	amount3 := mrand.Intn(999)
+	swap.Add(int64(amount1), testPeer2.Peer)
+	swap.Add(int64(0-amount2), testPeer2.Peer)
+	swap.Add(int64(0-amount3), testPeer2.Peer)
+
+	expectedBalance = expectedBalance + int64(amount1-amount2-amount3)
+	realBalance = swap.balances[testPeer2.ID()]
+
+	if expectedBalance != realBalance {
+		t.Fatal(fmt.Sprintf("After mixed debits and credits, expected balance to be: %d, but is: %d", expectedBalance, realBalance))
+	}
+}
+
+//try restoring a balance from state store
+//this is simulated by creating a node,
+//assigning it an arbitrary balance,
+//then closing the state store.
+//Then we re-open the state store and check that
+//the balance is still the same
+func TestRestoreBalanceFromStateStore(t *testing.T) {
+	//create a test swap account
+	swap, testDir := createTestSwap(t)
+	defer os.RemoveAll(testDir)
+
+	testPeer := newDummyPeer()
+	swap.balances[testPeer.ID()] = -8888
+
+	tmpBalance := swap.balances[testPeer.ID()]
+	swap.stateStore.Put(testPeer.ID().String(), &tmpBalance)
+
+	swap.stateStore.Close()
+	swap.stateStore = nil
+
+	stateStore, err := state.NewDBStore(testDir)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var newBalance int64
+	stateStore.Get(testPeer.ID().String(), &newBalance)
+
+	//compare the balances
+	if tmpBalance != newBalance {
+		t.Fatal(fmt.Sprintf("Unexpected balance value after sending cheap message test. Expected balance: %d, balance is: %d",
+			tmpBalance, newBalance))
+	}
+}
+
+//create a test swap account
+//creates a stateStore for persistence and a Swap account
+func createTestSwap(t *testing.T) (*Swap, string) {
+	dir, err := ioutil.TempDir("", "swap_test_store")
+	if err != nil {
+		t.Fatal(err)
+	}
+	stateStore, err2 := state.NewDBStore(dir)
+	if err2 != nil {
+		t.Fatal(err2)
+	}
+	swap := New(stateStore)
+	return swap, dir
+}
+
+type dummyPeer struct {
+	*protocols.Peer
+}
+
+//creates a dummy protocols.Peer with dummy MsgReadWriter
+func newDummyPeer() *dummyPeer {
+	id := adapters.RandomNodeConfig().ID
+	protoPeer := protocols.NewPeer(p2p.NewPeer(id, "testPeer", nil), nil, nil)
+	dummy := &dummyPeer{
+		Peer: protoPeer,
+	}
+	return dummy
+}