*: Move sideband64k and pktline to protocol/

1 files changed, 39 insertions, 0 deletions

diff --git a/protocol/pktline/append.go b/protocol/pktline/append.go
new file mode 100644
index 00000000..9425e58e
--- /dev/null
+++ b/protocol/pktline/append.go
@@ -0,0 +1,39 @@
+package pktline
+
+import "fmt"
+
+// AppendData appends one data frame to dst.
+//
+// Empty payload is encoded as 0004.
+func AppendData(dst, payload []byte) ([]byte, error) {
+	if len(payload) > LargePacketDataMax {
+		return dst, fmt.Errorf("%w: %d > %d", ErrTooLarge, len(payload), LargePacketDataMax)
+	}
+
+	var hdr [4]byte
+
+	err := EncodeLengthHeader(&hdr, len(payload)+4)
+	if err != nil {
+		return dst, err
+	}
+
+	dst = append(dst, hdr[:]...)
+	dst = append(dst, payload...)
+
+	return dst, nil
+}
+
+// AppendFlushPkt appends control frame 0000 (flush-pkt).
+func AppendFlushPkt(dst []byte) []byte {
+	return append(dst, '0', '0', '0', '0')
+}
+
+// AppendDelimPkt appends control frame 0001 (delim-pkt).
+func AppendDelimPkt(dst []byte) []byte {
+	return append(dst, '0', '0', '0', '1')
+}
+
+// AppendResponseEndPkt appends control frame 0002 (response-end-pkt).
+func AppendResponseEndPkt(dst []byte) []byte {
+	return append(dst, '0', '0', '0', '2')
+}