package sftp import ( "encoding" "io" "sync" "github.com/pkg/errors" ) // conn implements a bidirectional channel on which client and server // connections are multiplexed. type conn struct { io.Reader io.WriteCloser sync.Mutex // used to serialise writes to sendPacket // sendPacketTest is needed to replicate packet issues in testing sendPacketTest func(w io.Writer, m encoding.BinaryMarshaler) error } func (c *conn) recvPacket() (uint8, []byte, error) { return recvPacket(c) } func (c *conn) sendPacket(m encoding.BinaryMarshaler) error { c.Lock() defer c.Unlock() if c.sendPacketTest != nil { return c.sendPacketTest(c, m) } return sendPacket(c, m) } type clientConn struct { conn wg sync.WaitGroup sync.Mutex // protects inflight inflight map[uint32]chan<- result // outstanding requests } // Close closes the SFTP session. func (c *clientConn) Close() error { defer c.wg.Wait() return c.conn.Close() } func (c *clientConn) loop() { defer c.wg.Done() err := c.recv() if err != nil { c.broadcastErr(err) } } // recv continuously reads from the server and forwards responses to the // appropriate channel. func (c *clientConn) recv() error { defer func() { c.conn.Lock() c.conn.Close() c.conn.Unlock() }() for { typ, data, err := c.recvPacket() if err != nil { return err } sid, _ := unmarshalUint32(data) c.Lock() ch, ok := c.inflight[sid] delete(c.inflight, sid) c.Unlock() if !ok { // This is an unexpected occurrence. Send the error // back to all listeners so that they terminate // gracefully. return errors.Errorf("sid: %v not fond", sid) } ch <- result{typ: typ, data: data} } } // result captures the result of receiving the a packet from the server type result struct { typ byte data []byte err error } type idmarshaler interface { id() uint32 encoding.BinaryMarshaler } func (c *clientConn) sendPacket(p idmarshaler) (byte, []byte, error) { ch := make(chan result, 2) c.dispatchRequest(ch, p) s := <-ch return s.typ, s.data, s.err } func (c *clientConn) dispatchRequest(ch chan<- result, p idmarshaler) { c.Lock() c.inflight[p.id()] = ch c.Unlock() if err := c.conn.sendPacket(p); err != nil { c.Lock() delete(c.inflight, p.id()) c.Unlock() ch <- result{err: err} } } // broadcastErr sends an error to all goroutines waiting for a response. func (c *clientConn) broadcastErr(err error) { c.Lock() listeners := make([]chan<- result, 0, len(c.inflight)) for _, ch := range c.inflight { listeners = append(listeners, ch) } c.Unlock() for _, ch := range listeners { ch <- result{err: err} } } type serverConn struct { conn } func (s *serverConn) sendError(p ider, err error) error { return s.sendPacket(statusFromError(p, err)) }