Reinject captured first packet on lazy peer activation and keep peer alive across endpoint swap

client/iface/wgproxy/bind/proxy.go

@@ -136,6 +136,15 @@ func (p *ProxyBind) CloseConn() error {
 	return p.close()
 }
 
+// InjectPacket writes b to the remote peer over the underlying transport.
+func (p *ProxyBind) InjectPacket(b []byte) error {
+	if p.remoteConn == nil {
+		return fmt.Errorf("proxy not started")
+	}
+	_, err := p.remoteConn.Write(b)
+	return err
+}
+
 func (p *ProxyBind) close() error {
 	if p.remoteConn == nil {
 		return nil

client/iface/wgproxy/ebpf/wrapper.go

@@ -219,6 +219,15 @@ func (p *ProxyWrapper) RedirectAs(endpoint *net.UDPAddr) {
 	p.pausedCond.L.Unlock()
 }
 
+// InjectPacket writes b to the remote peer over the underlying transport.
+func (p *ProxyWrapper) InjectPacket(b []byte) error {
+	if p.remoteConn == nil {
+		return fmt.Errorf("proxy not started")
+	}
+	_, err := p.remoteConn.Write(b)
+	return err
+}
+
 // CloseConn close the remoteConn and automatically remove the conn instance from the map
 func (p *ProxyWrapper) CloseConn() error {
 	if p.cancel == nil {

client/iface/wgproxy/proxy.go

@@ -18,4 +18,8 @@ type Proxy interface {
 	RedirectAs(endpoint *net.UDPAddr)
 	CloseConn() error
 	SetDisconnectListener(disconnected func())
+
+	// InjectPacket writes a raw packet directly to the remote peer over the underlying transport,
+	// bypassing WireGuard. Used to replay the captured lazyconn handshake initiation.
+	InjectPacket(b []byte) error
 }

client/iface/wgproxy/udp/proxy.go

@@ -147,6 +147,15 @@ func (p *WGUDPProxy) RedirectAs(endpoint *net.UDPAddr) {
 	p.sendPkg = p.srcFakerConn.SendPkg
 }
 
+// InjectPacket writes b to the remote peer over the underlying transport.
+func (p *WGUDPProxy) InjectPacket(b []byte) error {
+	if p.remoteConn == nil {
+		return fmt.Errorf("proxy not started")
+	}
+	_, err := p.remoteConn.Write(b)
+	return err
+}
+
 // CloseConn close the localConn
 func (p *WGUDPProxy) CloseConn() error {
 	if p.cancel == nil {