simple packet parser impl

pkg/util/packetparser/packetparser.go

@@ -0,0 +1,58 @@
+// Copyright 2024, Command Line Inc.
+// SPDX-License-Identifier: Apache-2.0
+
+package packetparser
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+)
+
+type PacketParser struct {
+	Reader io.Reader
+	Ch     chan []byte
+}
+
+func Parse(input io.Reader, packetCh chan []byte, rawCh chan []byte) error {
+	bufReader := bufio.NewReader(input)
+	defer close(packetCh)
+	defer close(rawCh)
+	for {
+		line, err := bufReader.ReadBytes('\n')
+		if err == io.EOF {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+		if len(line) <= 1 {
+			// just a blank line
+			continue
+		}
+		if bytes.HasPrefix(line, []byte{'#', '#', 'N', '{'}) && bytes.HasSuffix(line, []byte{'}', '\n'}) {
+			// strip off the leading "##" and trailing "\n" (single byte)
+			packetCh <- line[3 : len(line)-1]
+		} else {
+			rawCh <- line
+		}
+	}
+}
+
+func WritePacket(output io.Writer, packet []byte) error {
+	if len(packet) < 2 {
+		return nil
+	}
+	if packet[0] != '{' || packet[len(packet)-1] != '}' {
+		return fmt.Errorf("invalid packet, must start with '{' and end with '}'")
+	}
+	fullPacket := make([]byte, 0, len(packet)+5)
+	// we add the extra newline to make sure the ## appears at the beginning of the line
+	// since writer isn't buffered, we want to send this all at once
+	fullPacket = append(fullPacket, '\n', '#', '#', 'N')
+	fullPacket = append(fullPacket, packet...)
+	fullPacket = append(fullPacket, '\n')
+	_, err := output.Write(fullPacket)
+	return err
+}