protocol/packp: sideband muxer and demuxer (#143)

* format/pakp: sideband demuxer

* format/pakp: sideband muxer

* format/pakp: sideband demuxer and muxer

* protocol/pakp: sideband demuxer and muxer

* documentation and improvements

* improvements

* handle scan errors properly

1 files changed, 151 insertions, 0 deletions

diff --git a/plumbing/protocol/packp/sideband/demux_test.go b/plumbing/protocol/packp/sideband/demux_test.go
new file mode 100644
index 0000000..4814d89
--- /dev/null
+++ b/plumbing/protocol/packp/sideband/demux_test.go
@@ -0,0 +1,151 @@
+package sideband
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"io/ioutil"
+	"testing"
+
+	"gopkg.in/src-d/go-git.v4/plumbing/format/pktline"
+
+	. "gopkg.in/check.v1"
+)
+
+func Test(t *testing.T) { TestingT(t) }
+
+type SidebandSuite struct{}
+
+var _ = Suite(&SidebandSuite{})
+
+func (s *SidebandSuite) TestDecode(c *C) {
+	expected := []byte("abcdefghijklmnopqrstuvwxyz")
+
+	buf := bytes.NewBuffer(nil)
+	e := pktline.NewEncoder(buf)
+	e.Encode(PackData.WithPayload(expected[0:8]))
+	e.Encode(PackData.WithPayload(expected[8:16]))
+	e.Encode(PackData.WithPayload(expected[16:26]))
+
+	content := make([]byte, 26)
+	d := NewDemuxer(Sideband64k, buf)
+	n, err := io.ReadFull(d, content)
+	c.Assert(err, IsNil)
+	c.Assert(n, Equals, 26)
+	c.Assert(content, DeepEquals, expected)
+}
+
+func (s *SidebandSuite) TestDecodeMoreThanContain(c *C) {
+	expected := []byte("abcdefghijklmnopqrstuvwxyz")
+
+	buf := bytes.NewBuffer(nil)
+	e := pktline.NewEncoder(buf)
+	e.Encode(PackData.WithPayload(expected))
+
+	content := make([]byte, 42)
+	d := NewDemuxer(Sideband64k, buf)
+	n, err := io.ReadFull(d, content)
+	c.Assert(err, Equals, io.ErrUnexpectedEOF)
+	c.Assert(n, Equals, 26)
+	c.Assert(content[0:26], DeepEquals, expected)
+}
+
+func (s *SidebandSuite) TestDecodeWithError(c *C) {
+	expected := []byte("abcdefghijklmnopqrstuvwxyz")
+
+	buf := bytes.NewBuffer(nil)
+	e := pktline.NewEncoder(buf)
+	e.Encode(PackData.WithPayload(expected[0:8]))
+	e.Encode(ErrorMessage.WithPayload([]byte{'F', 'O', 'O', '\n'}))
+	e.Encode(PackData.WithPayload(expected[8:16]))
+	e.Encode(PackData.WithPayload(expected[16:26]))
+
+	content := make([]byte, 26)
+	d := NewDemuxer(Sideband64k, buf)
+	n, err := io.ReadFull(d, content)
+	c.Assert(err, ErrorMatches, "unexpected error: FOO\n")
+	c.Assert(n, Equals, 8)
+	c.Assert(content[0:8], DeepEquals, expected[0:8])
+}
+
+type mockReader struct{}
+
+func (r *mockReader) Read([]byte) (int, error) { return 0, errors.New("foo") }
+
+func (s *SidebandSuite) TestDecodeFromFailingReader(c *C) {
+	content := make([]byte, 26)
+	d := NewDemuxer(Sideband64k, &mockReader{})
+	n, err := io.ReadFull(d, content)
+	c.Assert(err, ErrorMatches, "foo")
+	c.Assert(n, Equals, 0)
+}
+
+func (s *SidebandSuite) TestDecodeWithProgress(c *C) {
+	expected := []byte("abcdefghijklmnopqrstuvwxyz")
+
+	buf := bytes.NewBuffer(nil)
+	e := pktline.NewEncoder(buf)
+	e.Encode(PackData.WithPayload(expected[0:8]))
+	e.Encode(ProgressMessage.WithPayload([]byte{'F', 'O', 'O', '\n'}))
+	e.Encode(PackData.WithPayload(expected[8:16]))
+	e.Encode(PackData.WithPayload(expected[16:26]))
+
+	content := make([]byte, 26)
+	d := NewDemuxer(Sideband64k, buf)
+	n, err := io.ReadFull(d, content)
+	c.Assert(err, IsNil)
+	c.Assert(n, Equals, 26)
+	c.Assert(content, DeepEquals, expected)
+
+	progress, err := ioutil.ReadAll(d.Progress)
+	c.Assert(err, IsNil)
+	c.Assert(progress, DeepEquals, []byte{'F', 'O', 'O', '\n'})
+}
+
+func (s *SidebandSuite) TestDecodeWithUnknownChannel(c *C) {
+
+	buf := bytes.NewBuffer(nil)
+	e := pktline.NewEncoder(buf)
+	e.Encode([]byte{'4', 'F', 'O', 'O', '\n'})
+
+	content := make([]byte, 26)
+	d := NewDemuxer(Sideband64k, buf)
+	n, err := io.ReadFull(d, content)
+	c.Assert(err, ErrorMatches, "unknown channel 4FOO\n")
+	c.Assert(n, Equals, 0)
+}
+
+func (s *SidebandSuite) TestDecodeWithPending(c *C) {
+	expected := []byte("abcdefghijklmnopqrstuvwxyz")
+
+	buf := bytes.NewBuffer(nil)
+	e := pktline.NewEncoder(buf)
+	e.Encode(PackData.WithPayload(expected[0:8]))
+	e.Encode(PackData.WithPayload(expected[8:16]))
+	e.Encode(PackData.WithPayload(expected[16:26]))
+
+	content := make([]byte, 13)
+	d := NewDemuxer(Sideband64k, buf)
+	n, err := io.ReadFull(d, content)
+	c.Assert(err, IsNil)
+	c.Assert(n, Equals, 13)
+	c.Assert(content, DeepEquals, expected[0:13])
+
+	n, err = d.Read(content)
+	c.Assert(err, IsNil)
+	c.Assert(n, Equals, 13)
+	c.Assert(content, DeepEquals, expected[13:26])
+}
+
+func (s *SidebandSuite) TestDecodeErrMaxPacked(c *C) {
+	buf := bytes.NewBuffer(nil)
+	e := pktline.NewEncoder(buf)
+	e.Encode(PackData.WithPayload(bytes.Repeat([]byte{'0'}, MaxPackedSize+1)))
+
+	content := make([]byte, 13)
+	d := NewDemuxer(Sideband, buf)
+	n, err := io.ReadFull(d, content)
+	c.Assert(err, Equals, ErrMaxPackedExceeded)
+	c.Assert(n, Equals, 0)
+
+}