Merge #264

264: Untangle Bob's `EventLoop` from the `Builder` r=thomaseizinger a=thomaseizinger

This is work towards #255.

Co-authored-by: Thomas Eizinger <thomas@eizinger.io>

swap/src/bin/asb.rs

@@ -89,7 +89,7 @@ async fn main() -> Result<()> {
             let (bitcoin_wallet, monero_wallet) = init_wallets(
                 config.clone(),
                 &wallet_data_dir,
-                seed.extended_private_key(BITCOIN_NETWORK)?,
+                seed.derive_extended_private_key(BITCOIN_NETWORK)?,
             )
             .await?;
 
@@ -100,7 +100,7 @@ async fn main() -> Result<()> {
 
             let rate_service = kraken::RateService::new().await?;
 
-            let (mut event_loop, _) = EventLoop::new(
+            let (event_loop, _) = EventLoop::new(
                 config.network.listen,
                 seed,
                 execution_params,

swap/src/bin/swap_cli.rs

@@ -31,7 +31,7 @@ use swap::{
     monero::{CreateWallet, OpenWallet},
     protocol::{
         bob,
-        bob::{cancel::CancelError, Builder},
+        bob::{cancel::CancelError, Builder, EventLoop},
     },
     seed::Seed,
 };
@@ -111,6 +111,7 @@ async fn main() -> Result<()> {
                 init_bitcoin_wallet(config, bitcoin_network, &wallet_data_dir, seed).await?;
             let monero_wallet =
                 init_monero_wallet(monero_network, monero_wallet_rpc_process.endpoint()).await?;
+            let bitcoin_wallet = Arc::new(bitcoin_wallet);
 
             let swap_id = Uuid::new_v4();
 
@@ -137,19 +138,25 @@ async fn main() -> Result<()> {
 
             let send_bitcoin = bitcoin_wallet.max_giveable(TxLock::script_size()).await?;
 
-            let bob_factory = Builder::new(
-                seed,
+            let (event_loop, event_loop_handle) = EventLoop::new(
+                &seed.derive_libp2p_identity(),
+                alice_peer_id,
+                alice_addr,
+                bitcoin_wallet.clone(),
+            )?;
+            let handle = tokio::spawn(event_loop.run());
+
+            let swap = Builder::new(
                 db,
                 swap_id,
-                Arc::new(bitcoin_wallet),
+                bitcoin_wallet.clone(),
                 Arc::new(monero_wallet),
-                alice_addr,
-                alice_peer_id,
                 execution_params,
-            );
-            let (swap, event_loop) = bob_factory.with_init_params(send_bitcoin).build().await?;
+                event_loop_handle,
+            )
+            .with_init_params(send_bitcoin)
+            .build()?;
 
-            let handle = tokio::spawn(async move { event_loop.run().await });
             let swap = bob::run(swap);
             tokio::select! {
                 event_loop_result = handle => {
@@ -181,19 +188,26 @@ async fn main() -> Result<()> {
                 init_bitcoin_wallet(config, bitcoin_network, &wallet_data_dir, seed).await?;
             let monero_wallet =
                 init_monero_wallet(monero_network, monero_wallet_rpc_process.endpoint()).await?;
+            let bitcoin_wallet = Arc::new(bitcoin_wallet);
 
-            let bob_factory = Builder::new(
-                seed,
+            let (event_loop, event_loop_handle) = EventLoop::new(
+                &seed.derive_libp2p_identity(),
+                alice_peer_id,
+                alice_addr,
+                bitcoin_wallet.clone(),
+            )?;
+            let handle = tokio::spawn(event_loop.run());
+
+            let swap = Builder::new(
                 db,
                 swap_id,
-                Arc::new(bitcoin_wallet),
+                bitcoin_wallet.clone(),
                 Arc::new(monero_wallet),
-                alice_addr,
-                alice_peer_id,
                 execution_params,
-            );
-            let (swap, event_loop) = bob_factory.build().await?;
-            let handle = tokio::spawn(async move { event_loop.run().await });
+                event_loop_handle,
+            )
+            .build()?;
+
             let swap = bob::run(swap);
             tokio::select! {
                 event_loop_result = handle => {
@@ -256,7 +270,7 @@ async fn init_bitcoin_wallet(
         config.bitcoin.electrum_http_url,
         bitcoin_network,
         bitcoin_wallet_data_dir,
-        seed.extended_private_key(bitcoin_network)?,
+        seed.derive_extended_private_key(bitcoin_network)?,
     )
     .await?;
 

swap/src/network.rs

@@ -2,10 +2,8 @@ pub mod peer_tracker;
 pub mod request_response;
 pub mod transport;
 
-use crate::seed::SEED_LENGTH;
-use bitcoin::hashes::{sha256, Hash, HashEngine};
 use futures::prelude::*;
-use libp2p::{core::Executor, identity::ed25519};
+use libp2p::core::Executor;
 use std::pin::Pin;
 use tokio::runtime::Handle;
 
@@ -19,35 +17,3 @@ impl Executor for TokioExecutor {
         let _ = self.handle.spawn(future);
     }
 }
-
-#[derive(Debug, Clone, Copy, Eq, PartialEq)]
-pub struct Seed([u8; SEED_LENGTH]);
-
-impl Seed {
-    /// prefix "NETWORK" to the provided seed and apply sha256
-    pub fn new(seed: crate::seed::Seed) -> Self {
-        let mut engine = sha256::HashEngine::default();
-
-        engine.input(&seed.bytes());
-        engine.input(b"NETWORK");
-
-        let hash = sha256::Hash::from_engine(engine);
-        Self(hash.into_inner())
-    }
-
-    fn bytes(&self) -> [u8; SEED_LENGTH] {
-        self.0
-    }
-
-    pub fn derive_libp2p_identity(&self) -> libp2p::identity::Keypair {
-        let mut engine = sha256::HashEngine::default();
-
-        engine.input(&self.bytes());
-        engine.input(b"LIBP2P_IDENTITY");
-
-        let hash = sha256::Hash::from_engine(engine);
-        let key =
-            ed25519::SecretKey::from_bytes(hash.into_inner()).expect("we always pass 32 bytes");
-        libp2p::identity::Keypair::Ed25519(key.into())
-    }
-}

swap/src/protocol/alice/event_loop.rs

@@ -5,7 +5,6 @@ use crate::{
     execution_params::ExecutionParams,
     monero,
     monero::{Amount, BalanceTooLow},
-    network,
     network::{transport, TokioExecutor},
     protocol::{
         alice,
@@ -113,7 +112,7 @@ where
         rate_service: RS,
         max_sell: Amount,
     ) -> Result<(Self, mpsc::Receiver<RemoteHandle<Result<AliceState>>>)> {
-        let identity = network::Seed::new(seed).derive_libp2p_identity();
+        let identity = seed.derive_libp2p_identity();
         let behaviour = Behaviour::default();
         let transport = transport::build(&identity)?;
         let peer_id = PeerId::from(identity.public());
@@ -159,7 +158,7 @@ where
         self.peer_id
     }
 
-    pub async fn run(&mut self) {
+    pub async fn run(mut self) {
         loop {
             tokio::select! {
                 swarm_event = self.swarm.next().fuse() => {

swap/src/protocol/bob.rs

@@ -4,16 +4,12 @@ use crate::{
     bitcoin,
     database::Database,
     execution_params::ExecutionParams,
-    monero, network,
-    network::{
-        peer_tracker::{self, PeerTracker},
-        transport::build,
-    },
+    monero,
+    network::peer_tracker::{self, PeerTracker},
     protocol::{alice, alice::TransferProof, bob},
-    seed::Seed,
 };
 use anyhow::{Error, Result};
-use libp2p::{core::Multiaddr, identity::Keypair, NetworkBehaviour, PeerId};
+use libp2p::{core::Multiaddr, NetworkBehaviour, PeerId};
 use std::sync::Arc;
 use tracing::debug;
 use uuid::Uuid;
@@ -52,18 +48,15 @@ pub struct Swap {
 
 pub struct Builder {
     swap_id: Uuid,
-    identity: Keypair,
-    peer_id: PeerId,
     db: Database,
 
-    alice_address: Multiaddr,
-    alice_peer_id: PeerId,
-
     bitcoin_wallet: Arc<bitcoin::Wallet>,
     monero_wallet: Arc<monero::Wallet>,
 
     init_params: InitParams,
     execution_params: ExecutionParams,
+
+    event_loop_handle: bob::EventLoopHandle,
 }
 
 enum InitParams {
@@ -74,29 +67,21 @@ enum InitParams {
 impl Builder {
     #[allow(clippy::too_many_arguments)]
     pub fn new(
-        seed: Seed,
         db: Database,
         swap_id: Uuid,
         bitcoin_wallet: Arc<bitcoin::Wallet>,
         monero_wallet: Arc<monero::Wallet>,
-        alice_address: Multiaddr,
-        alice_peer_id: PeerId,
         execution_params: ExecutionParams,
+        event_loop_handle: bob::EventLoopHandle,
     ) -> Self {
-        let identity = network::Seed::new(seed).derive_libp2p_identity();
-        let peer_id = identity.public().into_peer_id();
-
         Self {
             swap_id,
-            identity,
-            peer_id,
             db,
-            alice_address,
-            alice_peer_id,
             bitcoin_wallet,
             monero_wallet,
             init_params: InitParams::None,
             execution_params,
+            event_loop_handle,
         }
     }
 
@@ -107,62 +92,21 @@ impl Builder {
         }
     }
 
-    pub async fn build(self) -> Result<(bob::Swap, bob::EventLoop)> {
-        match self.init_params {
-            InitParams::New { btc_amount } => {
-                let initial_state = BobState::Started { btc_amount };
+    pub fn build(self) -> Result<bob::Swap> {
+        let state = match self.init_params {
+            InitParams::New { btc_amount } => BobState::Started { btc_amount },
+            InitParams::None => self.db.get_state(self.swap_id)?.try_into_bob()?.into(),
+        };
 
-                let (event_loop, event_loop_handle) = self.init_event_loop()?;
-
-                Ok((
-                    Swap {
-                        state: initial_state,
-                        event_loop_handle,
+        Ok(Swap {
+            state,
+            event_loop_handle: self.event_loop_handle,
             db: self.db,
             bitcoin_wallet: self.bitcoin_wallet.clone(),
             monero_wallet: self.monero_wallet.clone(),
             swap_id: self.swap_id,
             execution_params: self.execution_params,
-                    },
-                    event_loop,
-                ))
-            }
-
-            InitParams::None => {
-                let resume_state = self.db.get_state(self.swap_id)?.try_into_bob()?.into();
-
-                let (event_loop, event_loop_handle) = self.init_event_loop()?;
-
-                Ok((
-                    Swap {
-                        state: resume_state,
-                        event_loop_handle,
-                        db: self.db,
-                        bitcoin_wallet: self.bitcoin_wallet.clone(),
-                        monero_wallet: self.monero_wallet.clone(),
-                        swap_id: self.swap_id,
-                        execution_params: self.execution_params,
-                    },
-                    event_loop,
-                ))
-            }
-        }
-    }
-
-    fn init_event_loop(
-        &self,
-    ) -> Result<(bob::event_loop::EventLoop, bob::event_loop::EventLoopHandle)> {
-        let bob_behaviour = bob::Behaviour::default();
-        let bob_transport = build(&self.identity)?;
-
-        bob::event_loop::EventLoop::new(
-            bob_transport,
-            bob_behaviour,
-            self.peer_id,
-            self.alice_peer_id,
-            self.alice_address.clone(),
-            self.bitcoin_wallet.clone(),
-        )
+        })
     }
 }
 

swap/src/protocol/bob/event_loop.rs

@@ -1,7 +1,7 @@
 use crate::{
     bitcoin,
     bitcoin::EncryptedSignature,
-    network::{transport::SwapTransport, TokioExecutor},
+    network::{transport, TokioExecutor},
     protocol::{
         alice::{QuoteResponse, TransferProof},
         bob::{Behaviour, OutEvent, QuoteRequest, State0, State2},
@@ -114,14 +114,19 @@ pub struct EventLoop {
 
 impl EventLoop {
     pub fn new(
-        transport: SwapTransport,
-        behaviour: Behaviour,
-        peer_id: PeerId,
+        identity: &libp2p::core::identity::Keypair,
         alice_peer_id: PeerId,
         alice_addr: Multiaddr,
         bitcoin_wallet: Arc<bitcoin::Wallet>,
     ) -> Result<(Self, EventLoopHandle)> {
-        let mut swarm = libp2p::swarm::SwarmBuilder::new(transport, behaviour, peer_id)
+        let behaviour = Behaviour::default();
+        let transport = transport::build(identity)?;
+
+        let mut swarm = libp2p::swarm::SwarmBuilder::new(
+            transport,
+            behaviour,
+            identity.public().into_peer_id(),
+        )
         .executor(Box::new(TokioExecutor {
             handle: tokio::runtime::Handle::current(),
         }))

swap/src/seed.rs

@@ -2,6 +2,8 @@ use crate::fs::ensure_directory_exists;
 use ::bitcoin::secp256k1::{self, constants::SECRET_KEY_SIZE, SecretKey};
 use anyhow::Result;
 use bdk::bitcoin::util::bip32::ExtendedPrivKey;
+use bitcoin::hashes::{sha256, Hash, HashEngine};
+use libp2p::identity;
 use pem::{encode, Pem};
 use rand::prelude::*;
 use std::{
@@ -28,13 +30,21 @@ impl Seed {
         Ok(Seed(bytes))
     }
 
-    pub fn extended_private_key(&self, network: bitcoin::Network) -> Result<ExtendedPrivKey> {
-        let private_key = ExtendedPrivKey::new_master(network, &self.bytes())?;
+    pub fn derive_extended_private_key(
+        &self,
+        network: bitcoin::Network,
+    ) -> Result<ExtendedPrivKey> {
+        let seed = self.derive(b"BITCOIN_EXTENDED_PRIVATE_KEY").bytes();
+        let private_key = ExtendedPrivKey::new_master(network, &seed)?;
+
         Ok(private_key)
     }
 
-    pub fn bytes(&self) -> [u8; SEED_LENGTH] {
-        self.0
+    pub fn derive_libp2p_identity(&self) -> identity::Keypair {
+        let bytes = self.derive(b"NETWORK").derive(b"LIBP2P_IDENTITY").bytes();
+        let key = identity::ed25519::SecretKey::from_bytes(bytes).expect("we always pass 32 bytes");
+
+        identity::Keypair::Ed25519(key.into())
     }
 
     pub fn from_file_or_generate(data_dir: &Path) -> Result<Self, Error> {
@@ -53,6 +63,26 @@ impl Seed {
         Ok(random_seed)
     }
 
+    /// Derive a new seed using the given scope.
+    ///
+    /// This function is purposely kept private because it is only a helper
+    /// function for deriving specific secret material from the root seed
+    /// like the libp2p identity or the seed for the Bitcoin wallet.
+    fn derive(&self, scope: &[u8]) -> Self {
+        let mut engine = sha256::HashEngine::default();
+
+        engine.input(&self.bytes());
+        engine.input(scope);
+
+        let hash = sha256::Hash::from_engine(engine);
+
+        Self(hash.into_inner())
+    }
+
+    fn bytes(&self) -> [u8; SEED_LENGTH] {
+        self.0
+    }
+
     fn from_file<D>(seed_file: D) -> Result<Self, Error>
     where
         D: AsRef<OsStr>,

swap/tests/testutils/mod.rs

@@ -54,16 +54,23 @@ struct BobParams {
 }
 
 impl BobParams {
-    pub fn builder(&self) -> bob::Builder {
+    pub fn builder(&self, event_loop_handle: bob::EventLoopHandle) -> bob::Builder {
         bob::Builder::new(
-            self.seed,
             Database::open(&self.db_path.clone().as_path()).unwrap(),
             self.swap_id,
             self.bitcoin_wallet.clone(),
             self.monero_wallet.clone(),
-            self.alice_address.clone(),
-            self.alice_peer_id,
             self.execution_params,
+            event_loop_handle,
+        )
+    }
+
+    pub fn new_eventloop(&self) -> Result<(bob::EventLoop, bob::EventLoopHandle)> {
+        bob::EventLoop::new(
+            &self.seed.derive_libp2p_identity(),
+            self.alice_peer_id,
+            self.alice_address.clone(),
+            self.bitcoin_wallet.clone(),
         )
     }
 }
@@ -95,15 +102,16 @@ pub struct TestContext {
 
 impl TestContext {
     pub async fn new_swap_as_bob(&mut self) -> (bob::Swap, BobEventLoopJoinHandle) {
-        let (swap, event_loop) = self
+        let (event_loop, event_loop_handle) = self.bob_params.new_eventloop().unwrap();
+
+        let swap = self
             .bob_params
-            .builder()
+            .builder(event_loop_handle)
             .with_init_params(self.btc_amount)
             .build()
-            .await
             .unwrap();
 
-        let join_handle = tokio::spawn(async move { event_loop.run().await });
+        let join_handle = tokio::spawn(event_loop.run());
 
         (swap, BobEventLoopJoinHandle(join_handle))
     }
@@ -114,9 +122,11 @@ impl TestContext {
     ) -> (bob::Swap, BobEventLoopJoinHandle) {
         join_handle.abort();
 
-        let (swap, event_loop) = self.bob_params.builder().build().await.unwrap();
+        let (event_loop, event_loop_handle) = self.bob_params.new_eventloop().unwrap();
 
-        let join_handle = tokio::spawn(async move { event_loop.run().await });
+        let swap = self.bob_params.builder(event_loop_handle).build().unwrap();
+
+        let join_handle = tokio::spawn(event_loop.run());
 
         (swap, BobEventLoopJoinHandle(join_handle))
     }
@@ -376,7 +386,7 @@ where
     )
     .await;
 
-    let (mut alice_event_loop, alice_swap_handle) = alice::EventLoop::new(
+    let (alice_event_loop, alice_swap_handle) = alice::EventLoop::new(
         alice_listen_address.clone(),
         alice_seed,
         execution_params,
@@ -390,9 +400,7 @@ where
 
     let alice_peer_id = alice_event_loop.peer_id();
 
-    tokio::spawn(async move {
-        alice_event_loop.run().await;
-    });
+    tokio::spawn(alice_event_loop.run());
 
     let bob_params = BobParams {
         seed: Seed::random().unwrap(),
@@ -606,7 +614,7 @@ async fn init_test_wallets(
         electrum_http_url,
         bitcoin::Network::Regtest,
         datadir,
-        seed.extended_private_key(bitcoin::Network::Regtest)
+        seed.derive_extended_private_key(bitcoin::Network::Regtest)
             .expect("Could not create extended private key from seed"),
     )
     .await