drain inFlight packets in read/write methods

Fixes issue pkg#167

File read/write client methods were breaking out of the packet handling
loops with packets still 'in flight' (packets sent without reply from
server) when errors occured. This caused problems after the fact with
the returning packets interfearing with later calls.

This change makes sure all the in flight packets are processed (even if
just discarded) before breaking out of the loop and returning.

client.go

@@ -694,13 +694,13 @@ func (f *File) Read(b []byte) (int, error) {
 		inFlight--
 		if res.err != nil {
 			firstErr = offsetErr{offset: 0, err: res.err}
-			break
+			continue
 		}
 		reqID, data := unmarshalUint32(res.data)
 		req, ok := reqs[reqID]
 		if !ok {
 			firstErr = offsetErr{offset: 0, err: errors.Errorf("sid: %v not found", reqID)}
-			break
+			continue
 		}
 		delete(reqs, reqID)
 		switch res.typ {
@@ -710,7 +710,6 @@ func (f *File) Read(b []byte) (int, error) {
 					offset: req.offset,
 					err:    normaliseError(unmarshalStatus(reqID, res.data)),
 				}
-				break
 			}
 		case ssh_FXP_DATA:
 			l, data := unmarshalUint32(data)
@@ -724,7 +723,6 @@ func (f *File) Read(b []byte) (int, error) {
 			}
 		default:
 			firstErr = offsetErr{offset: 0, err: unimplementedPacketErr(res.typ)}
-			break
 		}
 	}
 	// If the error is anything other than EOF, then there
@@ -798,20 +796,19 @@ func (f *File) WriteTo(w io.Writer) (int64, error) {
 		inFlight--
 		if res.err != nil {
 			firstErr = offsetErr{offset: 0, err: res.err}
-			break
+			continue
 		}
 		reqID, data := unmarshalUint32(res.data)
 		req, ok := reqs[reqID]
 		if !ok {
 			firstErr = offsetErr{offset: 0, err: errors.Errorf("sid: %v not found", reqID)}
-			break
+			continue
 		}
 		delete(reqs, reqID)
 		switch res.typ {
 		case ssh_FXP_STATUS:
 			if firstErr.err == nil || req.offset < firstErr.offset {
 				firstErr = offsetErr{offset: req.offset, err: normaliseError(unmarshalStatus(reqID, res.data))}
-				break
 			}
 		case ssh_FXP_DATA:
 			l, data := unmarshalUint32(data)
@@ -864,7 +861,6 @@ func (f *File) WriteTo(w io.Writer) (int64, error) {
 			}
 		default:
 			firstErr = offsetErr{offset: 0, err: unimplementedPacketErr(res.typ)}
-			break
 		}
 	}
 	if firstErr.err != io.EOF {
@@ -921,7 +917,7 @@ func (f *File) Write(b []byte) (int, error) {
 		inFlight--
 		if res.err != nil {
 			firstErr = res.err
-			break
+			continue
 		}
 		switch res.typ {
 		case ssh_FXP_STATUS:
@@ -936,7 +932,6 @@ func (f *File) Write(b []byte) (int, error) {
 			}
 		default:
 			firstErr = unimplementedPacketErr(res.typ)
-			break
 		}
 	}
 	// If error is non-nil, then there may be gaps in the data written to
@@ -986,7 +981,7 @@ func (f *File) ReadFrom(r io.Reader) (int64, error) {
 		inFlight--
 		if res.err != nil {
 			firstErr = res.err
-			break
+			continue
 		}
 		switch res.typ {
 		case ssh_FXP_STATUS:
@@ -1001,7 +996,6 @@ func (f *File) ReadFrom(r io.Reader) (int64, error) {
 			}
 		default:
 			firstErr = unimplementedPacketErr(res.typ)
-			break
 		}
 	}
 	if firstErr == io.EOF {