Add grpc multi conn

infra/conf/grpc.go

@@ -14,6 +14,7 @@ type GRPCConfig struct {
 	PermitWithoutStream bool   `json:"permit_without_stream"`
 	InitialWindowsSize  int32  `json:"initial_windows_size"`
 	UserAgent           string `json:"user_agent"`
+	MultiConnections	int32  `json:"multi_connections"`
 }
 
 func (g *GRPCConfig) Build() (proto.Message, error) {
@@ -37,5 +38,6 @@ func (g *GRPCConfig) Build() (proto.Message, error) {
 		PermitWithoutStream: g.PermitWithoutStream,
 		InitialWindowsSize:  g.InitialWindowsSize,
 		UserAgent:           g.UserAgent,
+		MultiConnections:    g.MultiConnections,
 	}, nil
 }

transport/internet/grpc/config.pb.go

@@ -33,6 +33,7 @@ type Config struct {
 	PermitWithoutStream bool   `protobuf:"varint,6,opt,name=permit_without_stream,json=permitWithoutStream,proto3" json:"permit_without_stream,omitempty"`
 	InitialWindowsSize  int32  `protobuf:"varint,7,opt,name=initial_windows_size,json=initialWindowsSize,proto3" json:"initial_windows_size,omitempty"`
 	UserAgent           string `protobuf:"bytes,8,opt,name=user_agent,json=userAgent,proto3" json:"user_agent,omitempty"`
+	MultiConnections    int32  `protobuf:"varint,9,opt,name=multi_connections,json=multiConnections,proto3" json:"multi_connections,omitempty"`
 }
 
 func (x *Config) Reset() {
@@ -121,6 +122,13 @@ func (x *Config) GetUserAgent() string {
 	return ""
 }
 
+func (x *Config) GetMultiConnections() int32 {
+	if x != nil {
+		return x.MultiConnections
+	}
+	return 0
+}
+
 var File_transport_internet_grpc_config_proto protoreflect.FileDescriptor
 
 var file_transport_internet_grpc_config_proto_rawDesc = []byte{
@@ -128,7 +136,7 @@ var file_transport_internet_grpc_config_proto_rawDesc = []byte{
 	0x72, 0x6e, 0x65, 0x74, 0x2f, 0x67, 0x72, 0x70, 0x63, 0x2f, 0x63, 0x6f, 0x6e, 0x66, 0x69, 0x67,
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@@ -149,10 +157,13 @@ var file_transport_internet_grpc_config_proto_rawDesc = []byte{
 	0x12, 0x69, 0x6e, 0x69, 0x74, 0x69, 0x61, 0x6c, 0x57, 0x69, 0x6e, 0x64, 0x6f, 0x77, 0x73, 0x53,
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+	0x6e, 0x74, 0x12, 0x2b, 0x0a, 0x11, 0x6d, 0x75, 0x6c, 0x74, 0x69, 0x5f, 0x63, 0x6f, 0x6e, 0x6e,
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+	0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x73, 0x18, 0x09, 0x20, 0x01, 0x28, 0x05, 0x52, 0x10, 0x6d,
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+	0x6c, 0x73, 0x2f, 0x78, 0x72, 0x61, 0x79, 0x2d, 0x63, 0x6f, 0x72, 0x65, 0x2f, 0x74, 0x72, 0x61,
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+	0x67, 0x72, 0x70, 0x63, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (

transport/internet/grpc/config.proto

@@ -12,4 +12,5 @@ message Config {
   bool permit_without_stream = 6;
   int32 initial_windows_size = 7;
   string user_agent = 8;
+  int32 multi_connections = 9;
 }

transport/internet/grpc/dial.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/xtls/xray-core/common"
 	c "github.com/xtls/xray-core/common/ctx"
+	"github.com/xtls/xray-core/common/dice"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/common/session"
@@ -42,8 +43,61 @@ type dialerConf struct {
 	*internet.MemoryStreamConfig
 }
 
+type globalDialers struct {
+	connMap map[dialerConf][]*grpc.ClientConn
+}
+
+// getClientConn returns a client connection from the global dialer if the connections already reached the target number
+// otherwise return nil
+func (d *globalDialers) getClientConn(conf dialerConf) (*grpc.ClientConn, int) {
+	if d.connMap == nil {
+		d.connMap = make(map[dialerConf][]*grpc.ClientConn)
+	}
+	if d.connMap[conf] == nil {
+		d.connMap[conf] = []*grpc.ClientConn{}
+	}
+
+	conns := d.connMap[conf]
+
+	targetConnsNum := conf.MemoryStreamConfig.ProtocolSettings.(*Config).MultiConnections
+	if targetConnsNum > int32(len(conns)) {
+		return nil, 0
+	} else {
+		index := dice.Roll(len(conns))
+		return conns[index], index
+	}
+}
+
+// addClientConn adds a client connection to the global dialer
+func (d *globalDialers) addClientConn(conf dialerConf, conn *grpc.ClientConn) error {
+	if d.connMap == nil {
+		d.connMap = make(map[dialerConf][]*grpc.ClientConn)
+	}
+	if d.connMap[conf] == nil {
+		d.connMap[conf] = []*grpc.ClientConn{}
+	}
+
+	conns := d.connMap[conf]
+	targetConnsNum := conf.MemoryStreamConfig.ProtocolSettings.(*Config).MultiConnections
+	if targetConnsNum <= int32(len(conns)) {
+		return errors.New("failed to add client connection beacuse reach the limit")
+	} else {
+		conns = append(conns, conn)
+		d.connMap[conf] = conns
+		return nil
+	}
+}
+
+// updateClientConnWithIndex updates a client connection with the given index
+// in the case if the clientConn is shutting down, replace it with the new one
+func (d *globalDialers) updateClientConnWithIndex(conf dialerConf, conn *grpc.ClientConn, index int) error {
+	conns := d.connMap[conf]
+	conns[index] = conn
+	return nil
+}
+
 var (
-	globalDialerMap    map[dialerConf]*grpc.ClientConn
+	globalDialer       globalDialers
 	globalDialerAccess sync.Mutex
 )
 
@@ -77,15 +131,13 @@ func getGrpcClient(ctx context.Context, dest net.Destination, streamSettings *in
 	globalDialerAccess.Lock()
 	defer globalDialerAccess.Unlock()
 
-	if globalDialerMap == nil {
-		globalDialerMap = make(map[dialerConf]*grpc.ClientConn)
-	}
 	tlsConfig := tls.ConfigFromStreamSettings(streamSettings)
 	realityConfig := reality.ConfigFromStreamSettings(streamSettings)
 	sockopt := streamSettings.SocketSettings
 	grpcSettings := streamSettings.ProtocolSettings.(*Config)
 
-	if client, found := globalDialerMap[dialerConf{dest, streamSettings}]; found && client.GetState() != connectivity.Shutdown {
+	client, index := globalDialer.getClientConn(dialerConf{dest, streamSettings})
+	if client != nil && client.GetState() != connectivity.Shutdown {
 		return client, nil
 	}
 
@@ -183,6 +235,14 @@ func getGrpcClient(ctx context.Context, dest net.Destination, streamSettings *in
 		gonet.JoinHostPort(grpcDestHost, dest.Port.String()),
 		dialOptions...,
 	)
-	globalDialerMap[dialerConf{dest, streamSettings}] = conn
+	if client == nil {
+		err := globalDialer.addClientConn(dialerConf{dest, streamSettings}, conn)
+		if err != nil {
+			return nil, err
+		}
+	}
+	if client != nil && client.GetState() == connectivity.Shutdown {
+		globalDialer.updateClientConnWithIndex(dialerConf{dest, streamSettings}, conn, index)
+	}
 	return conn, err
 }