examples/go-integration: Add ChannelProposal

- Go: Change go-side to accept any incomming channel (and a wallet
  related fix)
- Rust: Uncomment channel proposal and receive of accept message
- Rust: Change order of values in encoded assets (Asset.MarshalBinary),
  see hyperledger-labs/perun-eth-backend#36 for
  why this wasn't correct beforehand. Additionally, this PR is required
  for this example to work correctly, as go-perun will throw away all
  proposed channels because the Asset list isn't
  deserialized/unmarshaled correctly.

Signed-off-by: Jens <jens@perun.network>

examples/go-integration.rs

@@ -120,8 +120,8 @@ fn main() {
         participant: addr,
     };
     // Propose new channel and wait for responses
-    // let mut channel = client.propose_channel(prop);
-    // bus.recv_envelope();
+    let mut channel = client.propose_channel(prop);
+    bus.recv_envelope();
     // match bus.rx.recv().unwrap() {
     //     ParticipantMessage::ProposalAccepted(msg) => {
     //         channel.participant_accepted(1, msg).unwrap();

examples/go-integration/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"crypto/rand"
 	"math/big"
 	"os"
 	"os/signal"
@@ -16,10 +17,12 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 	ethchannel "github.com/perun-network/perun-eth-backend/channel"
 	phd "github.com/perun-network/perun-eth-backend/wallet/hd"
+	"github.com/sirupsen/logrus"
 	"perun.network/go-perun/channel"
 	"perun.network/go-perun/client"
+	perunlogrus "perun.network/go-perun/log/logrus"
+	"perun.network/go-perun/wallet"
 	"perun.network/go-perun/watcher/local"
-	"perun.network/go-perun/wire"
 	wirenet "perun.network/go-perun/wire/net"
 	"perun.network/go-perun/wire/net/simple"
 	"perun.network/go-perun/wire/protobuf"
@@ -44,6 +47,8 @@ func ToWei(value int64, denomination string) *big.Int {
 }
 
 func main() {
+	perunlogrus.Set(logrus.TraceLevel, &logrus.TextFormatter{})
+
 	w := NewSimpleWallet()
 	account := w.GenerateNewAccount()
 	deployer_account := w.GenerateNewAccount()
@@ -91,9 +96,9 @@ func main() {
 		account.Address,
 		account,
 	)
-	perunID := wire.NewAddress()
+	perunID := simple.NewAddress("Bob")
 	bus := wirenet.NewBus(
-		simple.NewAccount(simple.NewAddress("Bob")),
+		simple.NewAccount(perunID),
 		simple.NewTCPDialer(time.Minute),
 		protobuf.Serializer(),
 	)
@@ -110,8 +115,13 @@ func main() {
 	if err != nil {
 		panic(err)
 	}
-
-	var proposalHandler client.ProposalHandler = ProposalHandler{}
+	bob_account, err := wallet.NewAccount()
+	if err != nil {
+		panic(err)
+	}
+	var proposalHandler client.ProposalHandler = ProposalHandler{
+		addr: bob_account.Address(),
+	}
 	var updateHandler client.UpdateHandler = UpdateHandler{}
 
 	listener, err := simple.NewTCPListener("127.0.0.1:1337")
@@ -133,11 +143,30 @@ func main() {
 	println("Done")
 }
 
-type ProposalHandler struct{}
+type ProposalHandler struct {
+	addr wallet.Address
+}
 
 // HandleProposal implements client.ProposalHandler
-func (ProposalHandler) HandleProposal(proposal client.ChannelProposal, res *client.ProposalResponder) {
+func (ph ProposalHandler) HandleProposal(proposal client.ChannelProposal, res *client.ProposalResponder) {
 	println("HandleProposal(): ", proposal, res)
+
+	var nonce_share [32]byte
+	_, err := rand.Read(nonce_share[:])
+	if err != nil {
+		panic(err)
+	}
+
+	_, err = res.Accept(context.Background(), &client.LedgerChannelProposalAccMsg{
+		BaseChannelProposalAcc: client.BaseChannelProposalAcc{
+			ProposalID: proposal.Base().ProposalID,
+			NonceShare: nonce_share,
+		},
+		Participant: ph.addr,
+	})
+	if err != nil {
+		panic(err)
+	}
 }
 
 type UpdateHandler struct{}

examples/go-integration/simple_wallet.go

@@ -23,6 +23,7 @@ func NewSimpleWallet() *SimpleWallet {
 type SimpleWallet struct {
 	accounts []accounts.Account
 	keys     map[common.Address]*ecdsa.PrivateKey
+	derived  map[string]accounts.Account
 }
 
 var _ accounts.Wallet = (*SimpleWallet)(nil)
@@ -60,8 +61,12 @@ func (w *SimpleWallet) Contains(account accounts.Account) bool {
 }
 
 // Derive implements accounts.Wallet
-func (*SimpleWallet) Derive(path accounts.DerivationPath, pin bool) (accounts.Account, error) {
-	panic("unimplemented")
+func (w *SimpleWallet) Derive(path accounts.DerivationPath, pin bool) (accounts.Account, error) {
+	acc, ok := w.derived[path.String()]
+	if !ok {
+		acc = w.GenerateNewAccount()
+	}
+	return acc, nil
 }
 
 // Open implements accounts.Wallet

src/channel/fixed_size_payment.rs

@@ -192,20 +192,22 @@ impl<const A: usize, const P: usize> From<Allocation<A, P>> for perunwire::Alloc
             assets: value
                 .assets
                 .map(|a| {
-                    // go-perun currently uses `encoding/binary` in go and
-                    // manually adds the length of each field.
                     let mut b = vec![];
-                    b.append(&mut 20u16.to_le_bytes().to_vec()); // Length of asset holder (address)
-                    b.append(&mut a.holder.0.to_vec());
+
                     // go-perun uses less bytes, as it strips away some leading
                     // zeroes, which this implementation does not (for
                     // simplicity). However this should still be understandable
                     // by go-perun.
-                    b.append(&mut 32u16.to_le_bytes().to_vec());
+                    b.extend_from_slice(&32u16.to_le_bytes());
                     let mut buf = [0u8; 32];
                     a.chain_id.to_big_endian(&mut buf);
                     b.extend_from_slice(&buf);
 
+                    // go-perun currently uses `encoding/binary` in go and
+                    // manually adds the length of each field.
+                    b.extend_from_slice(&20u16.to_le_bytes()); // Length of asset holder (address)
+                    b.extend_from_slice(&a.holder.0);
+
                     b
                 })
                 .to_vec(),

src/channel/proposal.rs

@@ -93,7 +93,7 @@ impl From<LedgerChannelProposal> for perunwire::LedgerChannelProposalMsg {
                 funding_agreement: Some(value.funding_agreement.into()),
             }),
             participant: value.participant.0.to_vec(),
-            peers: vec![], // TODO: This is not empty!
+            peers: vec!["Alice".as_bytes().to_vec(), "Bob".as_bytes().to_vec()], // TODO: Use real data
         }
     }
 }