package tcp import ( "bufio" "bytes" "crypto/tls" "errors" "io" "net" "net/http" "slices" "time" "github.com/go-acme/lego/v4/challenge/tlsalpn01" "github.com/traefik/traefik/v2/pkg/log" tcpmuxer "github.com/traefik/traefik/v2/pkg/muxer/tcp" "github.com/traefik/traefik/v2/pkg/tcp" ) const defaultBufSize = 4096 // Router is a TCP router. type Router struct { // Contains TCP routes. muxerTCP tcpmuxer.Muxer // Contains TCP TLS routes. muxerTCPTLS tcpmuxer.Muxer // Contains HTTPS routes. muxerHTTPS tcpmuxer.Muxer // Forwarder handlers. // httpForwarder handles all HTTP requests. httpForwarder tcp.Handler // httpsForwarder handles (indirectly through muxerHTTPS, or directly) all HTTPS requests. httpsForwarder tcp.Handler // Neither is used directly, but they are held here, and recreated on config reload, // so that they can be passed to the Switcher at the end of the config reload phase. httpHandler http.Handler httpsHandler http.Handler // TLS configs. httpsTLSConfig *tls.Config // default TLS config // hostHTTPTLSConfig contains TLS configs keyed by SNI. // A nil config is the hint to set up a brokenTLSRouter. hostHTTPTLSConfig map[string]*tls.Config // TLS configs keyed by SNI } // NewRouter returns a new TCP router. func NewRouter() (*Router, error) { muxTCP, err := tcpmuxer.NewMuxer() if err != nil { return nil, err } muxTCPTLS, err := tcpmuxer.NewMuxer() if err != nil { return nil, err } muxHTTPS, err := tcpmuxer.NewMuxer() if err != nil { return nil, err } return &Router{ muxerTCP: *muxTCP, muxerTCPTLS: *muxTCPTLS, muxerHTTPS: *muxHTTPS, }, nil } // GetTLSGetClientInfo is called after a ClientHello is received from a client. func (r *Router) GetTLSGetClientInfo() func(info *tls.ClientHelloInfo) (*tls.Config, error) { return func(info *tls.ClientHelloInfo) (*tls.Config, error) { if tlsConfig, ok := r.hostHTTPTLSConfig[info.ServerName]; ok { return tlsConfig, nil } return r.httpsTLSConfig, nil } } // ServeTCP forwards the connection to the right TCP/HTTP handler. func (r *Router) ServeTCP(conn tcp.WriteCloser) { // Handling Non-TLS TCP connection early if there is neither HTTP(S) nor TLS routers on the entryPoint, // and if there is at least one non-TLS TCP router. // In the case of a non-TLS TCP client (that does not "send" first), // we would block forever on clientHelloInfo, // which is why we want to detect and handle that case first and foremost. if r.muxerTCP.HasRoutes() && !r.muxerTCPTLS.HasRoutes() && !r.muxerHTTPS.HasRoutes() { connData, err := tcpmuxer.NewConnData("", conn, nil) if err != nil { log.WithoutContext().Errorf("Error while reading TCP connection data: %v", err) conn.Close() return } handler, _ := r.muxerTCP.Match(connData) // If there is a handler matching the connection metadata, // we let it handle the connection. if handler != nil { handler.ServeTCP(conn) return } // Otherwise, we keep going because: // 1) we could be in the case where we have HTTP routers. // 2) if it is an HTTPS request, even though we do not have any TLS routers, // we still need to reply with a 404. } // TODO -- Check if ProxyProtocol changes the first bytes of the request br := bufio.NewReader(conn) hello, err := clientHelloInfo(br) if err != nil { conn.Close() return } // Remove read/write deadline and delegate this to underlying tcp server (for now only handled by HTTP Server) err = conn.SetReadDeadline(time.Time{}) if err != nil { log.WithoutContext().Errorf("Error while setting read deadline: %v", err) } err = conn.SetWriteDeadline(time.Time{}) if err != nil { log.WithoutContext().Errorf("Error while setting write deadline: %v", err) } connData, err := tcpmuxer.NewConnData(hello.serverName, conn, hello.protos) if err != nil { log.WithoutContext().Errorf("Error while reading TCP connection data: %v", err) conn.Close() return } if !hello.isTLS { handler, _ := r.muxerTCP.Match(connData) switch { case handler != nil: handler.ServeTCP(r.GetConn(conn, hello.peeked)) case r.httpForwarder != nil: r.httpForwarder.ServeTCP(r.GetConn(conn, hello.peeked)) default: conn.Close() } return } // Handling ACME-TLS/1 challenges. if slices.Contains(hello.protos, tlsalpn01.ACMETLS1Protocol) { r.acmeTLSALPNHandler().ServeTCP(r.GetConn(conn, hello.peeked)) return } // For real, the handler eventually used for HTTPS is (almost) always the same: // it is the httpsForwarder that is used for all HTTPS connections that match // (which is also incidentally the same used in the last block below for 404s). // The added value from doing Match is to find and use the specific TLS config // (wrapped inside the returned handler) requested for the given HostSNI. handlerHTTPS, catchAllHTTPS := r.muxerHTTPS.Match(connData) if handlerHTTPS != nil && !catchAllHTTPS { // In order not to depart from the behavior in 2.6, // we only allow an HTTPS router to take precedence over a TCP-TLS router if it is _not_ an HostSNI(*) router // (so basically any router that has a specific HostSNI based rule). handlerHTTPS.ServeTCP(r.GetConn(conn, hello.peeked)) return } // Contains also TCP TLS passthrough routes. handlerTCPTLS, catchAllTCPTLS := r.muxerTCPTLS.Match(connData) if handlerTCPTLS != nil && !catchAllTCPTLS { handlerTCPTLS.ServeTCP(r.GetConn(conn, hello.peeked)) return } // Fallback on HTTPS catchAll. // We end up here for e.g. an HTTPS router that only has a PathPrefix rule, // which under the scenes is counted as an HostSNI(*) rule. if handlerHTTPS != nil { handlerHTTPS.ServeTCP(r.GetConn(conn, hello.peeked)) return } // Fallback on TCP TLS catchAll. if handlerTCPTLS != nil { handlerTCPTLS.ServeTCP(r.GetConn(conn, hello.peeked)) return } // To handle 404s for HTTPS. if r.httpsForwarder != nil { r.httpsForwarder.ServeTCP(r.GetConn(conn, hello.peeked)) return } conn.Close() } // acmeTLSALPNHandler returns a special handler to solve ACME-TLS/1 challenges. func (r *Router) acmeTLSALPNHandler() tcp.Handler { if r.httpsTLSConfig == nil { return &brokenTLSRouter{} } return tcp.HandlerFunc(func(conn tcp.WriteCloser) { _ = tls.Server(conn, r.httpsTLSConfig).Handshake() }) } // AddRoute defines a handler for the given rule. func (r *Router) AddRoute(rule string, priority int, target tcp.Handler) error { return r.muxerTCP.AddRoute(rule, priority, target) } // AddHTTPTLSConfig defines a handler for a given sniHost and sets the matching tlsConfig. func (r *Router) AddHTTPTLSConfig(sniHost string, config *tls.Config) { if r.hostHTTPTLSConfig == nil { r.hostHTTPTLSConfig = map[string]*tls.Config{} } r.hostHTTPTLSConfig[sniHost] = config } // GetConn creates a connection proxy with a peeked string. func (r *Router) GetConn(conn tcp.WriteCloser, peeked string) tcp.WriteCloser { // TODO should it really be on Router ? conn = &Conn{ Peeked: []byte(peeked), WriteCloser: conn, } return conn } // GetHTTPHandler gets the attached http handler. func (r *Router) GetHTTPHandler() http.Handler { return r.httpHandler } // GetHTTPSHandler gets the attached https handler. func (r *Router) GetHTTPSHandler() http.Handler { return r.httpsHandler } // SetHTTPForwarder sets the tcp handler that will forward the connections to an http handler. func (r *Router) SetHTTPForwarder(handler tcp.Handler) { r.httpForwarder = handler } // brokenTLSRouter is associated to a Host(SNI) rule for which we know the TLS conf is broken. // It is used to make sure any attempt to connect to that hostname is closed, // since we cannot proceed with the intended TLS conf. type brokenTLSRouter struct{} // ServeTCP instantly closes the connection. func (t *brokenTLSRouter) ServeTCP(conn tcp.WriteCloser) { _ = conn.Close() } // SetHTTPSForwarder sets the tcp handler that will forward the TLS connections to an HTTP handler. // It also sets up each TLS handler (with its TLS config) for each Host(SNI) rule we previously kept track of. // It sets up a special handler that closes the connection if a TLS config is nil. func (r *Router) SetHTTPSForwarder(handler tcp.Handler) { for sniHost, tlsConf := range r.hostHTTPTLSConfig { var tcpHandler tcp.Handler if tlsConf == nil { tcpHandler = &brokenTLSRouter{} } else { tcpHandler = &tcp.TLSHandler{ Next: handler, Config: tlsConf, } } // muxerHTTPS only contains single HostSNI rules (and no other kind of rules), // so there's no need for specifying a priority for them. err := r.muxerHTTPS.AddRoute("HostSNI(`"+sniHost+"`)", 0, tcpHandler) if err != nil { log.WithoutContext().Errorf("Error while adding route for host: %v", err) } } if r.httpsTLSConfig == nil { r.httpsForwarder = &brokenTLSRouter{} return } r.httpsForwarder = &tcp.TLSHandler{ Next: handler, Config: r.httpsTLSConfig, } } // SetHTTPHandler attaches http handlers on the router. func (r *Router) SetHTTPHandler(handler http.Handler) { r.httpHandler = handler } // SetHTTPSHandler attaches https handlers on the router. func (r *Router) SetHTTPSHandler(handler http.Handler, config *tls.Config) { r.httpsHandler = handler r.httpsTLSConfig = config } // Conn is a connection proxy that handles Peeked bytes. type Conn struct { // Peeked are the bytes that have been read from Conn for the purposes of route matching, // but have not yet been consumed by Read calls. // It set to nil by Read when fully consumed. Peeked []byte // Conn is the underlying connection. // It can be type asserted against *net.TCPConn or other types as needed. // It should not be read from directly unless Peeked is nil. tcp.WriteCloser } // Read reads bytes from the connection (using the buffer prior to actually reading). func (c *Conn) Read(p []byte) (n int, err error) { if len(c.Peeked) > 0 { n = copy(p, c.Peeked) c.Peeked = c.Peeked[n:] if len(c.Peeked) == 0 { c.Peeked = nil } return n, nil } return c.WriteCloser.Read(p) } type clientHello struct { serverName string // SNI server name protos []string // ALPN protocols list isTLS bool // whether we are a TLS handshake peeked string // the bytes peeked from the hello while getting the info } // clientHelloInfo returns various data from the clientHello handshake, // without consuming any bytes from br. // It returns an error if it can't peek the first byte from the connection. func clientHelloInfo(br *bufio.Reader) (*clientHello, error) { hdr, err := br.Peek(1) if err != nil { var opErr *net.OpError if !errors.Is(err, io.EOF) && (!errors.As(err, &opErr) || opErr.Timeout()) { log.WithoutContext().Errorf("Error while Peeking first byte: %s", err) } return nil, err } // No valid TLS record has a type of 0x80, however SSLv2 handshakes start with an uint16 length // where the MSB is set and the first record is always < 256 bytes long. // Therefore, typ == 0x80 strongly suggests an SSLv2 client. const recordTypeSSLv2 = 0x80 const recordTypeHandshake = 0x16 if hdr[0] != recordTypeHandshake { if hdr[0] == recordTypeSSLv2 { // we consider SSLv2 as TLS, and it will be refused by real TLS handshake. return &clientHello{ isTLS: true, peeked: getPeeked(br), }, nil } return &clientHello{ peeked: getPeeked(br), }, nil // Not TLS. } const recordHeaderLen = 5 hdr, err = br.Peek(recordHeaderLen) if err != nil { log.Errorf("Error while Peeking hello: %s", err) return &clientHello{ peeked: getPeeked(br), }, nil } recLen := int(hdr[3])<<8 | int(hdr[4]) // ignoring version in hdr[1:3] if recordHeaderLen+recLen > defaultBufSize { br = bufio.NewReaderSize(br, recordHeaderLen+recLen) } helloBytes, err := br.Peek(recordHeaderLen + recLen) if err != nil { log.Errorf("Error while Hello: %s", err) return &clientHello{ isTLS: true, peeked: getPeeked(br), }, nil } sni := "" var protos []string server := tls.Server(helloSniffConn{r: bytes.NewReader(helloBytes)}, &tls.Config{ GetConfigForClient: func(hello *tls.ClientHelloInfo) (*tls.Config, error) { sni = hello.ServerName protos = hello.SupportedProtos return nil, nil }, }) _ = server.Handshake() return &clientHello{ serverName: sni, isTLS: true, peeked: getPeeked(br), protos: protos, }, nil } func getPeeked(br *bufio.Reader) string { peeked, err := br.Peek(br.Buffered()) if err != nil { log.Errorf("Could not get anything: %s", err) return "" } return string(peeked) } // helloSniffConn is a net.Conn that reads from r, fails on Writes, // and crashes otherwise. type helloSniffConn struct { r io.Reader net.Conn // nil; crash on any unexpected use } // Read reads from the underlying reader. func (c helloSniffConn) Read(p []byte) (int, error) { return c.r.Read(p) } // Write crashes all the time. func (helloSniffConn) Write(p []byte) (int, error) { return 0, io.EOF }