feat(pkg/p2p): reconnect on disconnected peers

CHANGELOG.md

@@ -9,6 +9,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changes
+
+- Improve P2P connection in case of transient network failure [#3212](https://github.com/evstack/ev-node/pull/3212)
+
 ## v1.1.0-rc.1
 
 ### Added

apps/evm/go.mod

@@ -2,10 +2,10 @@ module github.com/evstack/ev-node/apps/evm
 
 go 1.25.7
 
-// replace (
-// 	github.com/evstack/ev-node => ../../
-// 	github.com/evstack/ev-node/execution/evm => ../../execution/evm
-// )
+replace (
+	github.com/evstack/ev-node => ../../
+	github.com/evstack/ev-node/execution/evm => ../../execution/evm
+)
 
 require (
 	github.com/ethereum/go-ethereum v1.17.2

apps/evm/go.sum

@@ -472,12 +472,8 @@ github.com/ethereum/go-bigmodexpfix v0.0.0-20250911101455-f9e208c548ab h1:rvv6MJ
 github.com/ethereum/go-bigmodexpfix v0.0.0-20250911101455-f9e208c548ab/go.mod h1:IuLm4IsPipXKF7CW5Lzf68PIbZ5yl7FFd74l/E0o9A8=
 github.com/ethereum/go-ethereum v1.17.2 h1:ag6geu0kn8Hv5FLKTpH+Hm2DHD+iuFtuqKxEuwUsDOI=
 github.com/ethereum/go-ethereum v1.17.2/go.mod h1:KHcRXfGOUfUmKg51IhQ0IowiqZ6PqZf08CMtk0g5K1o=
-github.com/evstack/ev-node v1.1.0-rc.1 h1:NtPuuDLqN2h4/edu5zxRlZAxmLkTG3ncXBO2PlCDvVs=
-github.com/evstack/ev-node v1.1.0-rc.1/go.mod h1:6rhWWzuyiqNn/erDmWCk1aLxUuQphyOGIRq56/smSyk=
 github.com/evstack/ev-node/core v1.0.0 h1:s0Tx0uWHme7SJn/ZNEtee4qNM8UO6PIxXnHhPbbKTz8=
 github.com/evstack/ev-node/core v1.0.0/go.mod h1:n2w/LhYQTPsi48m6lMj16YiIqsaQw6gxwjyJvR+B3sY=
-github.com/evstack/ev-node/execution/evm v1.0.0 h1:UTAdCrnPsLoGzSgsBx4Kv76jkXpMmHBIpNv3MxyzWPo=
-github.com/evstack/ev-node/execution/evm v1.0.0/go.mod h1:UrqkiepfTMiot6M8jnswgu3VU8SSucZpaMIHIl22/1A=
 github.com/fatih/color v1.7.0/go.mod h1:Zm6kSWBoL9eyXnKyktHP6abPY2pDugNf5KwzbycvMj4=
 github.com/fatih/color v1.10.0/go.mod h1:ELkj/draVOlAH/xkhN6mQ50Qd0MPOk5AAr3maGEBuJM=
 github.com/fatih/color v1.13.0/go.mod h1:kLAiJbzzSOZDVNGyDpeOxJ47H46qBXwg5ILebYFFOfk=

apps/testapp/go.mod

@@ -2,7 +2,7 @@ module github.com/evstack/ev-node/apps/testapp
 
 go 1.25.7
 
-// replace github.com/evstack/ev-node => ../../.
+replace github.com/evstack/ev-node => ../../.
 
 require (
 	github.com/evstack/ev-node v1.1.0-rc.1

apps/testapp/go.sum

@@ -432,8 +432,6 @@ github.com/envoyproxy/protoc-gen-validate v1.0.1/go.mod h1:0vj8bNkYbSTNS2PIyH87K
 github.com/envoyproxy/protoc-gen-validate v1.0.2/go.mod h1:GpiZQP3dDbg4JouG/NNS7QWXpgx6x8QiMKdmN72jogE=
 github.com/envoyproxy/protoc-gen-validate v1.3.0 h1:TvGH1wof4H33rezVKWSpqKz5NXWg5VPuZ0uONDT6eb4=
 github.com/envoyproxy/protoc-gen-validate v1.3.0/go.mod h1:HvYl7zwPa5mffgyeTUHA9zHIH36nmrm7oCbo4YKoSWA=
-github.com/evstack/ev-node v1.1.0-rc.1 h1:NtPuuDLqN2h4/edu5zxRlZAxmLkTG3ncXBO2PlCDvVs=
-github.com/evstack/ev-node v1.1.0-rc.1/go.mod h1:6rhWWzuyiqNn/erDmWCk1aLxUuQphyOGIRq56/smSyk=
 github.com/evstack/ev-node/core v1.0.0 h1:s0Tx0uWHme7SJn/ZNEtee4qNM8UO6PIxXnHhPbbKTz8=
 github.com/evstack/ev-node/core v1.0.0/go.mod h1:n2w/LhYQTPsi48m6lMj16YiIqsaQw6gxwjyJvR+B3sY=
 github.com/fatih/color v1.7.0/go.mod h1:Zm6kSWBoL9eyXnKyktHP6abPY2pDugNf5KwzbycvMj4=

pkg/p2p/client.go

@@ -6,6 +6,7 @@
 	"errors"
 	"fmt"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/ipfs/go-datastore"
@@ -28,13 +29,26 @@
 	rollhash "github.com/evstack/ev-node/pkg/hash"
 )
 
-// TODO(tzdybal): refactor to configuration parameters
 const (
 	// reAdvertisePeriod defines a period after which P2P client re-attempt advertising namespace in DHT.
 	reAdvertisePeriod = 1 * time.Hour
 
 	// peerLimit defines limit of number of peers returned during active peer discovery.
 	peerLimit = 60
+
+	// peerDiscoveryInterval is how often the background loop re-advertises and
+	// re-runs peer discovery via DHT.
+	peerDiscoveryInterval = 5 * time.Minute
+
+	// reconnectCooldown is the base cooldown between reconnect attempts for the same seed peer.
+	reconnectCooldown = 5 * time.Second
+
+	// maxReconnectCooldown caps the exponential backoff for seed peer reconnection.
+	maxReconnectCooldown = 5 * time.Minute
+
+	// connectWorkers limits the number of concurrent connection attempts during
+	// periodic peer discovery refresh.
+	connectWorkers = 16
 )
 
 // Client is a P2P client, implemented with libp2p.
@@ -56,6 +70,13 @@
 	ps      *pubsub.PubSub
 	started bool
 
+	seedPeers []peer.AddrInfo
+
+	maintenanceCancel context.CancelFunc
+	maintenanceWg     sync.WaitGroup
+	reconnectCh       chan peer.ID
+	connectSem        chan struct{}
+
 	metrics *Metrics
 }
 
@@ -164,17 +185,29 @@
 		return err
 	}
 
+	c.reconnectCh = make(chan peer.ID, 32)
+	c.connectSem = make(chan struct{}, connectWorkers)
+
 	c.logger.Debug().Msg("setting up active peer discovery")
 	if err := c.peerDiscovery(ctx); err != nil {
 		return err
 	}
 
 	c.started = true
+
+	c.host.Network().Notify(c.newDisconnectNotifee())
+	c.startConnectionMaintenance()
+
 	return nil
 }
 
 // Close gently stops Client.
 func (c *Client) Close() error {
+	if c.maintenanceCancel != nil {
+		c.maintenanceCancel()
+	}
+	c.maintenanceWg.Wait()
+
 	var err error
 	if c.dht != nil {
 		err = errors.Join(err, c.dht.Close())
@@ -245,6 +278,142 @@
 	return res
 }
 
+// disconnectNotifee is a network.Notifee that triggers seed peer reconnection
+// when a configured seed peer disconnects.
+type disconnectNotifee struct {
+	c *Client
+}
+
+func (n disconnectNotifee) Connected(_ network.Network, _ network.Conn)          {}
+func (n disconnectNotifee) OpenedStream(_ network.Network, _ network.Stream)     {}
+func (n disconnectNotifee) ClosedStream(_ network.Network, _ network.Stream)     {}
+func (n disconnectNotifee) Listen(_ network.Network, _ multiaddr.Multiaddr)      {}
+func (n disconnectNotifee) ListenClose(_ network.Network, _ multiaddr.Multiaddr) {}
+
+func (n disconnectNotifee) Disconnected(_ network.Network, conn network.Conn) {
+	p := conn.RemotePeer()
+	if n.c.reconnectCh == nil {
+		return
+	}
+	for _, sp := range n.c.seedPeers {
+		if sp.ID == p {
+			select {
+			case n.c.reconnectCh <- p:
+			default:
+			}
+			return
+		}
+	}
+}
+
+func (c *Client) newDisconnectNotifee() disconnectNotifee {
+	return disconnectNotifee{c: c}
+}
+
+// startConnectionMaintenance launches a background goroutine that reconnects
+// to seed peers on disconnect (driven by network.Notifee events) and
+// periodically refreshes peer discovery. This ensures P2P connectivity
+// recovers after transient network failures without requiring a full node restart.
+func (c *Client) startConnectionMaintenance() {
+	ctx, cancel := context.WithCancel(context.Background())
+	c.maintenanceCancel = cancel
+
+	c.maintenanceWg.Go(func() {
+
+		discoveryTicker := time.NewTicker(peerDiscoveryInterval)
+		defer discoveryTicker.Stop()
+
+		type reconnectState struct {
+			lastAttempt time.Time
+			attempts    int
+		}
+		states := make(map[peer.ID]*reconnectState)
+
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case pid := <-c.reconnectCh:
+				st := states[pid]
+				if st == nil {
+					st = &reconnectState{}
+					states[pid] = st
+				}
+
+				if time.Since(st.lastAttempt) > maxReconnectCooldown {
+					st.attempts = 0
+				}
+
+				backoff := reconnectCooldown * time.Duration(1<<min(st.attempts, 6))
+				if backoff > maxReconnectCooldown {
+					backoff = maxReconnectCooldown
+				}
+				if time.Now().Before(st.lastAttempt.Add(backoff)) {
+					continue
+				}
+				st.lastAttempt = time.Now()
+
+				for _, sp := range c.seedPeers {
+					if sp.ID != pid {
+						continue
+					}
+					if c.isConnected(sp.ID) {
+						st.attempts = 0
+						break
+					}
+					st.attempts++
+					c.logger.Info().Str("peer", sp.ID.String()).Msg("reconnecting to disconnected seed peer")
+					go func(info peer.AddrInfo) {
+						if err := c.host.Connect(ctx, info); err != nil && ctx.Err() == nil {
+							c.logger.Warn().Str("peer", info.ID.String()).Err(err).Msg("failed to reconnect to seed peer")
+						}
+					}(sp)
+					break
+				}
+			case <-discoveryTicker.C:
+				c.refreshPeerDiscovery(ctx)
+			}
+		}
+	})
+}
+
+// refreshPeerDiscovery re-advertises and re-runs peer discovery via DHT.
+func (c *Client) refreshPeerDiscovery(ctx context.Context) {
+	if c.disc == nil {
+		return
+	}
+
+	c.logger.Debug().Msg("refreshing peer discovery")
+
+	_ = c.advertise(ctx)
+
+	peerCh, err := c.disc.FindPeers(ctx, c.getNamespace(), cdiscovery.Limit(peerLimit))
+	if err != nil {
+		c.logger.Warn().Err(err).Msg("peer discovery refresh failed")
+		return
+	}
+
+	for p := range peerCh {
+		if p.ID == c.host.ID() || c.isConnected(p.ID) {
+			continue
+		}
+		select {
+		case c.connectSem <- struct{}{}:
+			go func(peer peer.AddrInfo) {
+				defer func() { <-c.connectSem }()
+				c.tryConnect(ctx, peer)
+			}(p)
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+// isConnected returns true if there is an active connection to the given peer.
+func (c *Client) isConnected(id peer.ID) bool {
+	return c.host.Network().Connectedness(id) == network.Connected
+}
+
 func (c *Client) listen() (host.Host, error) {
 	maddr, err := multiaddr.NewMultiaddr(c.conf.ListenAddress)
 	if err != nil {
@@ -256,6 +425,7 @@
 
 func (c *Client) setupDHT(ctx context.Context) error {
 	peers := c.parseAddrInfoList(c.conf.Peers)
+	c.seedPeers = peers
 	if len(peers) == 0 {
 		c.logger.Info().Msg("no peers - only listening for connections")
 	}

pkg/signer/aws/signer.go

@@ -159,7 +159,7 @@ func (s *KmsSigner) Sign(ctx context.Context, message []byte) ([]byte, error) {
 	timeout := s.opts.timeout()
 	maxAttempts := maxRetries + 1
 
-	for attempt := 0; attempt < maxAttempts; attempt++ {
+	for attempt := range maxAttempts {
 		if err := ctx.Err(); err != nil {
 			return nil, err
 		}

pkg/signer/gcp/signer.go

@@ -189,7 +189,7 @@ func (s *KmsSigner) Sign(ctx context.Context, message []byte) ([]byte, error) {
 	timeout := s.opts.timeout()
 	maxAttempts := maxRetries + 1
 
-	for attempt := 0; attempt < maxAttempts; attempt++ {
+	for attempt := range maxAttempts {
 		if err := ctx.Err(); err != nil {
 			return nil, err
 		}