chunking: rewrite to handle EOF events correctly

bonus: some tests asserting the chunking protocol is adhered to

util/chunking_test.go

@@ -0,0 +1,73 @@
+package chunking
+
+import (
+	"bytes"
+	"encoding/binary"
+	"github.com/stretchr/testify/assert"
+	"io"
+	"reflect"
+	"testing"
+	"testing/quick"
+)
+
+func TestUnchunker(t *testing.T) {
+
+	buf := bytes.Buffer{}
+	binary.Write(&buf, ChunkHeaderByteOrder, uint32(2))
+	buf.WriteByte(0xca)
+	buf.WriteByte(0xfe)
+	binary.Write(&buf, ChunkHeaderByteOrder, uint32(0))
+	buf.WriteByte(0xff) // sentinel, should not be read
+
+	un := NewUnchunker(&buf)
+
+	recv := bytes.Buffer{}
+	n, err := io.Copy(&recv, un)
+	assert.Nil(t, err)
+	assert.Equal(t, int64(2), n)
+	assert.Equal(t, []byte{0xca, 0xfe}, recv.Bytes())
+
+}
+
+func TestChunker(t *testing.T) {
+
+	buf := bytes.Buffer{}
+	buf.WriteByte(0xca)
+	buf.WriteByte(0xfe)
+
+	ch := NewChunker(&buf)
+
+	chunked := bytes.Buffer{}
+	n, err := io.Copy(&chunked, &ch)
+	assert.Nil(t, err)
+	assert.Equal(t, int64(4+2+4), n)
+	assert.Equal(t, []byte{0x2, 0x0, 0x0, 0x0, 0xca, 0xfe, 0x0, 0x0, 0x0, 0x0}, chunked.Bytes())
+
+}
+
+func TestUnchunkerUnchunksChunker(t *testing.T) {
+
+	f := func(b []byte) bool {
+
+		buf := bytes.NewBuffer(b)
+		ch := NewChunker(buf)
+		unch := NewUnchunker(&ch)
+		var tx bytes.Buffer
+		_, err := io.Copy(&tx, unch)
+		if err != nil {
+			return false
+		}
+
+		return reflect.DeepEqual(b, tx.Bytes())
+	}
+
+	cfg := quick.Config{
+		MaxCount:      3 * int(ChunkBufSize),
+		MaxCountScale: 2.0,
+	}
+
+	if err := quick.Check(f, &cfg); err != nil {
+		t.Error(err)
+	}
+
+}