Add SNI shunt support for Trojan fallbacks

infra/conf/trojan.go

@@ -85,6 +85,7 @@ func (c *TrojanClientConfig) Build() (proto.Message, error) {
 
 // TrojanInboundFallback is fallback configuration
 type TrojanInboundFallback struct {
+	Name string          `json:"name"`
 	Alpn string          `json:"alpn"`
 	Path string          `json:"path"`
 	Type string          `json:"type"`
@@ -144,6 +145,7 @@ func (c *TrojanServerConfig) Build() (proto.Message, error) {
 			_ = json.Unmarshal(fb.Dest, &s)
 		}
 		config.Fallbacks = append(config.Fallbacks, &trojan.Fallback{
+			Name: fb.Name,
 			Alpn: fb.Alpn,
 			Path: fb.Path,
 			Type: fb.Type,

proxy/trojan/config.pb.go

@@ -86,11 +86,12 @@ type Fallback struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
-	Alpn string `protobuf:"bytes,1,opt,name=alpn,proto3" json:"alpn,omitempty"`
+	Name string `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
-	Path string `protobuf:"bytes,2,opt,name=path,proto3" json:"path,omitempty"`
+	Alpn string `protobuf:"bytes,2,opt,name=alpn,proto3" json:"alpn,omitempty"`
-	Type string `protobuf:"bytes,3,opt,name=type,proto3" json:"type,omitempty"`
+	Path string `protobuf:"bytes,3,opt,name=path,proto3" json:"path,omitempty"`
-	Dest string `protobuf:"bytes,4,opt,name=dest,proto3" json:"dest,omitempty"`
+	Type string `protobuf:"bytes,4,opt,name=type,proto3" json:"type,omitempty"`
-	Xver uint64 `protobuf:"varint,5,opt,name=xver,proto3" json:"xver,omitempty"`
+	Dest string `protobuf:"bytes,5,opt,name=dest,proto3" json:"dest,omitempty"`
+	Xver uint64 `protobuf:"varint,6,opt,name=xver,proto3" json:"xver,omitempty"`
 }
 
 func (x *Fallback) Reset() {
@@ -125,6 +126,13 @@ func (*Fallback) Descriptor() ([]byte, []int) {
 	return file_proxy_trojan_config_proto_rawDescGZIP(), []int{1}
 }
 
+func (x *Fallback) GetName() string {
+	if x != nil {
+		return x.Name
+	}
+	return ""
+}
+
 func (x *Fallback) GetAlpn() string {
 	if x != nil {
 		return x.Alpn
@@ -275,33 +283,34 @@ var file_proxy_trojan_config_proto_rawDesc = []byte{
 	0x07, 0x41, 0x63, 0x63, 0x6f, 0x75, 0x6e, 0x74, 0x12, 0x1a, 0x0a, 0x08, 0x70, 0x61, 0x73, 0x73,
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 }
 
 var (

proxy/trojan/config.proto

@@ -15,11 +15,12 @@ message Account {
 }
 
 message Fallback {
-  string alpn = 1;
+  string name = 1;
-  string path = 2;
+  string alpn = 2;
-  string type = 3;
+  string path = 3;
-  string dest = 4;
+  string type = 4;
-  uint64 xver = 5;
+  string dest = 5;
+  uint64 xver = 6;
 }
 
 message ClientConfig {

proxy/trojan/server.go

@@ -5,6 +5,7 @@ import (
 	"crypto/tls"
 	"io"
 	"strconv"
+	"strings"
 	"syscall"
 	"time"
 
@@ -46,7 +47,7 @@ func init() {
 type Server struct {
 	policyManager policy.Manager
 	validator     *Validator
-	fallbacks     map[string]map[string]*Fallback // or nil
+	fallbacks     map[string]map[string]map[string]*Fallback // or nil
 	cone          bool
 }
 
@@ -72,17 +73,32 @@ func NewServer(ctx context.Context, config *ServerConfig) (*Server, error) {
 	}
 
 	if config.Fallbacks != nil {
-		server.fallbacks = make(map[string]map[string]*Fallback)
+		server.fallbacks = make(map[string]map[string]map[string]*Fallback)
 		for _, fb := range config.Fallbacks {
-			if server.fallbacks[fb.Alpn] == nil {
+			if server.fallbacks[fb.Name] == nil {
-				server.fallbacks[fb.Alpn] = make(map[string]*Fallback)
+				server.fallbacks[fb.Name] = make(map[string]map[string]*Fallback)
 			}
-			server.fallbacks[fb.Alpn][fb.Path] = fb
+			if server.fallbacks[fb.Name][fb.Alpn] == nil {
+				server.fallbacks[fb.Name][fb.Alpn] = make(map[string]*Fallback)
+			}
+			server.fallbacks[fb.Name][fb.Alpn][fb.Path] = fb
 		}
 		if server.fallbacks[""] != nil {
-			for alpn, pfb := range server.fallbacks {
+			for name, apfb := range server.fallbacks {
+				if name != "" {
+					for alpn := range server.fallbacks[""] {
+						if apfb[alpn] == nil {
+							apfb[alpn] = make(map[string]*Fallback)
+						}
+					}
+				}
+			}
+		}
+		for _, apfb := range server.fallbacks {
+			if apfb[""] != nil {
+				for alpn, pfb := range apfb {
 					if alpn != "" { // && alpn != "h2" {
-					for path, fb := range server.fallbacks[""] {
+						for path, fb := range apfb[""] {
 							if pfb[path] == nil {
 								pfb[path] = fb
 							}
@@ -91,6 +107,20 @@ func NewServer(ctx context.Context, config *ServerConfig) (*Server, error) {
 				}
 			}
 		}
+		if server.fallbacks[""] != nil {
+			for name, apfb := range server.fallbacks {
+				if name != "" {
+					for alpn, pfb := range server.fallbacks[""] {
+						for path, fb := range pfb {
+							if apfb[alpn][path] == nil {
+								apfb[alpn][path] = fb
+							}
+						}
+					}
+				}
+			}
+		}
+	}
 
 	return server, nil
 }
@@ -141,8 +171,8 @@ func (s *Server) Process(ctx context.Context, network net.Network, conn internet
 
 	var user *protocol.MemoryUser
 
-	apfb := s.fallbacks
+	napfb := s.fallbacks
-	isfb := apfb != nil
+	isfb := napfb != nil
 
 	shouldFallback := false
 	if firstLen < 58 || first.Byte(56) != '\r' {
@@ -173,7 +203,7 @@ func (s *Server) Process(ctx context.Context, network net.Network, conn internet
 	}
 
 	if isfb && shouldFallback {
-		return s.fallback(ctx, sid, err, sessionPolicy, conn, iConn, apfb, first, firstLen, bufferedReader)
+		return s.fallback(ctx, sid, err, sessionPolicy, conn, iConn, napfb, first, firstLen, bufferedReader)
 	} else if shouldFallback {
 		return newError("invalid protocol or invalid user")
 	}
@@ -361,25 +391,51 @@ func (s *Server) handleConnection(ctx context.Context, sessionPolicy policy.Sess
 	return nil
 }
 
-func (s *Server) fallback(ctx context.Context, sid errors.ExportOption, err error, sessionPolicy policy.Session, connection internet.Connection, iConn internet.Connection, apfb map[string]map[string]*Fallback, first *buf.Buffer, firstLen int64, reader buf.Reader) error {
+func (s *Server) fallback(ctx context.Context, sid errors.ExportOption, err error, sessionPolicy policy.Session, connection internet.Connection, iConn internet.Connection, napfb map[string]map[string]map[string]*Fallback, first *buf.Buffer, firstLen int64, reader buf.Reader) error {
 	if err := connection.SetReadDeadline(time.Time{}); err != nil {
 		newError("unable to set back read deadline").Base(err).AtWarning().WriteToLog(sid)
 	}
 	newError("fallback starts").Base(err).AtInfo().WriteToLog(sid)
 
+	name := ""
 	alpn := ""
-	if len(apfb) > 1 || apfb[""] == nil {
 	if tlsConn, ok := iConn.(*tls.Conn); ok {
-			alpn = tlsConn.ConnectionState().NegotiatedProtocol
+		cs := tlsConn.ConnectionState()
+		name = cs.ServerName
+		alpn = cs.NegotiatedProtocol
+		newError("realName = " + name).AtInfo().WriteToLog(sid)
 		newError("realAlpn = " + alpn).AtInfo().WriteToLog(sid)
 	} else if xtlsConn, ok := iConn.(*xtls.Conn); ok {
-			alpn = xtlsConn.ConnectionState().NegotiatedProtocol
+		cs := xtlsConn.ConnectionState()
+		name = cs.ServerName
+		alpn = cs.NegotiatedProtocol
+		newError("realName = " + name).AtInfo().WriteToLog(sid)
 		newError("realAlpn = " + alpn).AtInfo().WriteToLog(sid)
 	}
+
+	if len(napfb) > 1 || napfb[""] == nil {
+		if name != "" && napfb[name] == nil {
+			match := ""
+			for n := range napfb {
+				if n != "" && strings.Contains(name, n) && len(n) > len(match) {
+					match = n
+				}
+			}
+			name = match
+		}
+	}
+
+	if napfb[name] == nil {
+		name = ""
+	}
+	apfb := napfb[name]
+	if apfb == nil {
+		return newError(`failed to find the default "name" config`).AtWarning()
+	}
+
 	if apfb[alpn] == nil {
 		alpn = ""
 	}
-	}
 	pfb := apfb[alpn]
 	if pfb == nil {
 		return newError(`failed to find the default "alpn" config`).AtWarning()