package telebit import ( "bufio" "fmt" "net" "time" "git.coolaj86.com/coolaj86/go-telebitd/dbg" "git.coolaj86.com/coolaj86/go-telebitd/sni" ) // ConnWrap is just a cheap way to DRY up some switch conn.(type) statements to handle special features of Conn type ConnWrap struct { // TODO use io.MultiReader to unbuffer the peeker //Conn net.Conn peeker *bufio.Reader servername string scheme string Conn net.Conn Plain net.Conn encrypted *bool } type Peeker interface { Peek(n int) ([]byte, error) } func (c *ConnWrap) Peek(n int) ([]byte, error) { if nil != c.peeker { return c.peeker.Peek(n) } switch conn := c.Conn.(type) { case *ConnWrap: return conn.Peek(n) case *Conn: return conn.Peek(n) default: // *net.UDPConn,*net.TCPConn,*net.IPConn,*net.UnixConn if nil == c.peeker { c.peeker = bufio.NewReaderSize(c.Conn, defaultPeekerSize) } return c.peeker.Peek(n) } } func (c *ConnWrap) Read(b []byte) (n int, err error) { if nil != c.peeker { return c.peeker.Read(b) } return c.Conn.Read(b) } // Write writes data to the connection. // Write can be made to time out and return an Error with Timeout() == true // after a fixed time limit; see SetDeadline and SetWriteDeadline. func (c *ConnWrap) Write(b []byte) (n int, err error) { return c.Conn.Write(b) } // Close closes the connection. // Any blocked Read or Write operations will be unblocked and return errors. func (c *ConnWrap) Close() error { return c.Conn.Close() } // Scheme returns one of "https", "http", "tcp", "tls", or "" func (c *ConnWrap) Scheme() string { if "" != c.scheme { return c.scheme } /* if nil != c.Plain { tlsConn := &ConnWrap{Conn: c.Plain} // TODO upgrade tls+http => https c.scheme = tlsConn.Scheme() return c.scheme } */ switch conn := c.Conn.(type) { case *ConnWrap: return conn.Scheme() case *Conn: return string(conn.relayTargetAddr.scheme) } return "" } // CheckServername returns the servername without detection func (c *ConnWrap) CheckServername() string { return c.servername } // SetServername sets the servername without detection func (c *ConnWrap) SetServername(name string) { c.servername = name } // Servername may return Servername or Hostname as hinted by a tunnel or buffered peeking func (c *ConnWrap) Servername() string { if "" != c.servername { return c.servername } if nil != c.Plain { tlsConn := &ConnWrap{Conn: c.Plain} c.servername = tlsConn.Servername() return c.servername } switch conn := c.Conn.(type) { case *ConnWrap: //c.servername = conn.Servername() return conn.Servername() case *Conn: // TODO XXX //c.servername = string(conn.relayTargetAddr.addr) return string(conn.relayTargetAddr.addr) } // this will get the servername _ = c.isEncrypted() return c.servername } // isEncrypted returns true if peeking at net.Conn reveals that it is TLS-encrypted func (c *ConnWrap) isEncrypted() bool { if nil != c.encrypted { return *c.encrypted } var encrypted bool // TODO: how to allow / detect / handle protocols where the server hello happens first? c.SetDeadline(time.Now().Add(5 * time.Second)) n := 6 b, err := c.Peek(n) if dbg.Debug { fmt.Printf("[debug] [wrap] Peek(%d): %s %v\n", n, string(b), err) } if nil != err { // TODO return error on error? return encrypted } defer c.SetDeadline(time.Time{}) if len(b) >= n { // SSL v3.x / TLS v1.x // 0: TLS Byte // 1: Major Version // 2: Minor Version - 1 // 3-4: Header Length // Payload // 5: TLS Client Hello Marker Byte if 0x16 == b[0] && 0x03 == b[1] && 0x01 == b[5] { length := (int(b[3]) << 8) + int(b[4]) b, err := c.Peek(n - 1 + length) if nil != err { c.encrypted = &encrypted return *c.encrypted } c.servername, _ = sni.GetHostname(b) encrypted = true c.encrypted = &encrypted return *c.encrypted } } c.encrypted = &encrypted return *c.encrypted } // LocalAddr returns the local network address. func (c *ConnWrap) LocalAddr() net.Addr { // TODO is this the right one? return c.Conn.LocalAddr() } // RemoteAddr returns the remote network address. func (c *ConnWrap) RemoteAddr() net.Addr { // TODO is this the right one? return c.Conn.RemoteAddr() } // SetDeadline sets the read and write deadlines associated // with the connection. It is equivalent to calling both // SetReadDeadline and SetWriteDeadline. // // A deadline is an absolute time after which I/O operations // fail with a timeout (see type Error) instead of // blocking. The deadline applies to all future and pending // I/O, not just the immediately following call to Read or // Write. After a deadline has been exceeded, the connection // can be refreshed by setting a deadline in the future. // // An idle timeout can be implemented by repeatedly extending // the deadline after successful Read or Write calls. // // A zero value for t means I/O operations will not time out. // // Note that if a TCP connection has keep-alive turned on, // which is the default unless overridden by Dialer.KeepAlive // or ListenConfig.KeepAlive, then a keep-alive failure may // also return a timeout error. On Unix systems a keep-alive // failure on I/O can be detected using // errors.Is(err, syscall.ETIMEDOUT). func (c *ConnWrap) SetDeadline(t time.Time) error { return c.Conn.SetDeadline(t) } // SetReadDeadline sets the deadline for future Read calls // and any currently-blocked Read call. // A zero value for t means Read will not time out. func (c *ConnWrap) SetReadDeadline(t time.Time) error { return c.Conn.SetReadDeadline(t) } // SetWriteDeadline sets the deadline for future Write calls // and any currently-blocked Write call. // Even if write times out, it may return n > 0, indicating that // some of the data was successfully written. // A zero value for t means Write will not time out. func (c *ConnWrap) SetWriteDeadline(t time.Time) error { return c.Conn.SetWriteDeadline(t) }