Merge pull request #469 from mcuadros/fix-multiple-ack

plumbing: protocol, fix handling multiple ACK on upload-pack

1 files changed, 46 insertions, 3 deletions

diff --git a/plumbing/protocol/packp/srvresp.go b/plumbing/protocol/packp/srvresp.go
index 0c89e47..a5bec9c 100644
--- a/plumbing/protocol/packp/srvresp.go
+++ b/plumbing/protocol/packp/srvresp.go
@@ -1,6 +1,7 @@
 package packp
 
 import (
+	"bufio"
 	"bytes"
 	"errors"
 	"fmt"
@@ -18,8 +19,8 @@ type ServerResponse struct {
 }
 
 // Decode decodes the response into the struct, isMultiACK should be true, if
-// the request was done with multi_ack or multi_ack_detailed capabilities
-func (r *ServerResponse) Decode(reader io.Reader, isMultiACK bool) error {
+// the request was done with multi_ack or multi_ack_detailed capabilities.
+func (r *ServerResponse) Decode(reader *bufio.Reader, isMultiACK bool) error {
 	// TODO: implement support for multi_ack or multi_ack_detailed responses
 	if isMultiACK {
 		return errors.New("multi_ack and multi_ack_detailed are not supported")
@@ -34,7 +35,15 @@ func (r *ServerResponse) Decode(reader io.Reader, isMultiACK bool) error {
 			return err
 		}
 
-		if !isMultiACK {
+		// we need to detect when the end of a response header and the begining
+		// of a packfile header happend, some requests to the git daemon
+		// produces a duplicate ACK header even when multi_ack is not supported.
+		isEnd, err := r.endReached(reader)
+		if err != nil {
+			return err
+		}
+
+		if isEnd {
 			break
 		}
 	}
@@ -42,6 +51,40 @@ func (r *ServerResponse) Decode(reader io.Reader, isMultiACK bool) error {
 	return s.Err()
 }
 
+func (r *ServerResponse) endReached(reader *bufio.Reader) (bool, error) {
+	isPack, err := r.isPACKHeader(reader)
+	if err == io.EOF {
+		return true, nil
+	}
+
+	return isPack, err
+
+}
+
+// isPACKHeader detects when a header of a packfile is found, with this goal
+// the function is reading from the reader without moving the read pointer.
+func (r *ServerResponse) isPACKHeader(reader *bufio.Reader) (bool, error) {
+	ahead, err := reader.Peek(9)
+	if err != nil {
+		return false, err
+	}
+
+	if len(ahead) == 0 {
+		return true, nil
+	}
+
+	if len(ahead) > 4 && string(ahead[0:4]) == "PACK" {
+		return true, nil
+	}
+
+	if len(ahead) == 9 && string(ahead[5:]) == "PACK" {
+		return true, nil
+	}
+
+	return true, nil
+
+}
+
 func (r *ServerResponse) decodeLine(line []byte) error {
 	if len(line) == 0 {
 		return fmt.Errorf("unexpected flush")