From 9c61c6497a0062b8161f0a33f4368949c6b2ed4b Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Tue, 8 Nov 2022 18:00:32 +0000
Subject: [PATCH] refactor the transport constructor code to remove
 TransportWithOptions

---
 libp2p_test.go | 29 +++++++++++++++++++++++++++++
 options.go     | 42 ++++++++++++++++++++++++++++++++----------
 2 files changed, 61 insertions(+), 10 deletions(-)

diff --git a/libp2p_test.go b/libp2p_test.go
index 8e70eef3c5..97b07d7fb2 100644
--- a/libp2p_test.go
+++ b/libp2p_test.go
@@ -12,10 +12,13 @@ import (
 	"github.com/libp2p/go-libp2p/core/host"
 	"github.com/libp2p/go-libp2p/core/peer"
 	"github.com/libp2p/go-libp2p/core/transport"
+	"github.com/libp2p/go-libp2p/p2p/net/swarm"
 	"github.com/libp2p/go-libp2p/p2p/security/noise"
 	tls "github.com/libp2p/go-libp2p/p2p/security/tls"
+	quic "github.com/libp2p/go-libp2p/p2p/transport/quic"
 	"github.com/libp2p/go-libp2p/p2p/transport/tcp"
 
+	ma "github.com/multiformats/go-multiaddr"
 	"github.com/stretchr/testify/require"
 )
 
@@ -168,6 +171,32 @@ func TestChainOptions(t *testing.T) {
 	}
 }
 
+func TestTransportConstructorTCP(t *testing.T) {
+	h, err := New(
+		Transport(tcp.NewTCPTransport),
+		DisableRelay(),
+	)
+	require.NoError(t, err)
+	defer h.Close()
+	require.NoError(t, h.Network().Listen(ma.StringCast("/ip4/127.0.0.1/tcp/0")))
+	err = h.Network().Listen(ma.StringCast("/ip4/127.0.0.1/udp/0/quic"))
+	require.Error(t, err)
+	require.Contains(t, err.Error(), swarm.ErrNoTransport.Error())
+}
+
+func TestTransportConstructorQUIC(t *testing.T) {
+	h, err := New(
+		Transport(quic.NewTransport),
+		DisableRelay(),
+	)
+	require.NoError(t, err)
+	defer h.Close()
+	require.NoError(t, h.Network().Listen(ma.StringCast("/ip4/127.0.0.1/udp/0/quic")))
+	err = h.Network().Listen(ma.StringCast("/ip4/127.0.0.1/tcp/0"))
+	require.Error(t, err)
+	require.Contains(t, err.Error(), swarm.ErrNoTransport.Error())
+}
+
 func TestSecurityConstructor(t *testing.T) {
 	h, err := New(
 		Transport(tcp.NewTCPTransport),
diff --git a/options.go b/options.go
index 00246ba82e..56538eba48 100644
--- a/options.go
+++ b/options.go
@@ -4,8 +4,11 @@ package libp2p
 // those are in defaults.go).
 
 import (
+	"crypto/rand"
+	"encoding/binary"
 	"errors"
 	"fmt"
+	"reflect"
 	"time"
 
 	"github.com/libp2p/go-libp2p/config"
@@ -124,23 +127,42 @@ func Muxer(name string, muxer network.Multiplexer) Option {
 // * Public Key
 // * Address filter (filter.Filter)
 // * Peerstore
-func Transport[F any](tpt F) Option {
+func Transport(constructor interface{}, opts ...interface{}) Option {
 	return func(cfg *Config) error {
+		// generate a random identifier, so that fx can associate the constructor with its options
+		b := make([]byte, 8)
+		rand.Read(b)
+		id := binary.BigEndian.Uint64(b)
+
+		tag := fmt.Sprintf(`group:"transportopt_%d"`, id)
+
+		typ := reflect.ValueOf(constructor).Type()
+		numParams := typ.NumIn()
+		isVariadic := typ.IsVariadic()
+		var params []string
+		if isVariadic && len(opts) > 0 {
+			// If there are transport options, apply the tag.
+			// Since options are variadic, they have to be the last argument of the constructor.
+			params = make([]string, numParams)
+			params[len(params)-1] = tag
+		}
+
 		cfg.Transports = append(cfg.Transports, fx.Provide(
 			fx.Annotate(
-				tpt,
+				constructor,
+				fx.ParamTags(params...),
 				fx.As(new(transport.Transport)),
 				fx.ResultTags(`group:"transport"`),
 			),
 		))
-		return nil
-	}
-}
-
-func TransportWithOptions[F any, Opt any](tpt F, opts ...Opt) Option {
-	return func(cfg *Config) error {
-		cfg.Transports = append(cfg.Transports, fx.Provide(fx.Annotate(tpt, fx.ResultTags(`group:"transport"`))))
-		cfg.Transports = append(cfg.Transports, fx.Supply(opts))
+		for _, opt := range opts {
+			cfg.Transports = append(cfg.Transports, fx.Supply(
+				fx.Annotate(
+					opt,
+					fx.ResultTags(tag),
+				),
+			))
+		}
 		return nil
 	}
 }