From 86966132cad4ad7213785e9b5e4332cf97da25da Mon Sep 17 00:00:00 2001
From: Joel Wetzell <git@jwetzell.com>
Date: Tue, 18 Nov 2025 21:02:48 -0600
Subject: [PATCH] add concept of framing to net.tcp

---
 config.json                    |  3 ++-
 internals/framing/framer.go    |  6 +++++
 internals/framing/separator.go | 33 +++++++++++++++++++++++++++
 tcp-client.go                  | 39 +++++++++++++++++++++++++++++---
 tcp-server.go                  | 41 +++++++++++++++++++++++++++++-----
 5 files changed, 112 insertions(+), 10 deletions(-)
 create mode 100644 internals/framing/framer.go
 create mode 100644 internals/framing/separator.go

diff --git a/config.json b/config.json
index d30108a..0ad1321 100644
--- a/config.json
+++ b/config.json
@@ -3,7 +3,8 @@
         {
             "type": "net.tcp.server",
             "params": {
-                "port": 8000
+                "port": 8000,
+                "framing": "LF"
             }
         }
     ]
diff --git a/internals/framing/framer.go b/internals/framing/framer.go
new file mode 100644
index 0000000..3044f04
--- /dev/null
+++ b/internals/framing/framer.go
@@ -0,0 +1,6 @@
+package framing
+
+type Framer interface {
+	Frame([]byte) [][]byte
+	Clear()
+}
diff --git a/internals/framing/separator.go b/internals/framing/separator.go
new file mode 100644
index 0000000..03f3ed8
--- /dev/null
+++ b/internals/framing/separator.go
@@ -0,0 +1,33 @@
+package framing
+
+import (
+	"bytes"
+)
+
+type ByteSeparatorFramer struct {
+	buffer    []byte
+	separator []byte
+}
+
+func NewByteSeparatorFramer(separator []byte) *ByteSeparatorFramer {
+	return &ByteSeparatorFramer{separator: separator, buffer: []byte{}}
+}
+
+func (bsf *ByteSeparatorFramer) Frame(data []byte) [][]byte {
+	messages := [][]byte{}
+
+	bsf.buffer = append(bsf.buffer, data...)
+
+	parts := bytes.Split(bsf.buffer, bsf.separator)
+
+	if len(parts) > 0 {
+		bsf.buffer = parts[len(parts)-1]
+		messages = parts[:len(parts)-1]
+	}
+
+	return messages
+}
+
+func (bsf *ByteSeparatorFramer) Clear() {
+	bsf.buffer = []byte{}
+}
diff --git a/tcp-client.go b/tcp-client.go
index c7dde80..e1f18a6 100644
--- a/tcp-client.go
+++ b/tcp-client.go
@@ -6,12 +6,15 @@ import (
 	"log/slog"
 	"net"
 	"time"
+
+	"github.com/jwetzell/showbridge-go/internals/framing"
 )
 
 type TCPClient struct {
 	config ModuleConfig
 	Host   string
 	Port   uint16
+	framer framing.Framer
 }
 
 func init() {
@@ -42,7 +45,31 @@ func init() {
 				return nil, fmt.Errorf("tcp client port must be uint16")
 			}
 
-			return TCPClient{Host: hostString, Port: uint16(portNum), config: config}, nil
+			framingMethod, ok := params["framing"]
+			if !ok {
+				return nil, fmt.Errorf("tcp client requires a framing method")
+			}
+
+			framingMethodString, ok := framingMethod.(string)
+
+			if !ok {
+				return nil, fmt.Errorf("tcp framing method must be a string")
+			}
+
+			var framer framing.Framer
+
+			switch framingMethodString {
+			case "CR":
+				framer = framing.NewByteSeparatorFramer([]byte{'\r'})
+			case "LF":
+				framer = framing.NewByteSeparatorFramer([]byte{'\n'})
+			case "CRLF":
+				framer = framing.NewByteSeparatorFramer([]byte{'\r', '\n'})
+			default:
+				return nil, fmt.Errorf("unknown framing method: %s", framingMethodString)
+			}
+
+			return TCPClient{framer: framer, Host: hostString, Port: uint16(portNum), config: config}, nil
 		},
 	})
 }
@@ -79,11 +106,17 @@ func (tc TCPClient) Run(ctx context.Context) error {
 
 					if err != nil {
 						slog.Debug("connection closed")
+						tc.framer.Clear()
 						break READ
 					}
 
-					if byteCount > 0 {
-						slog.Info(string(buffer[0:byteCount]))
+					if tc.framer != nil {
+						if byteCount > 0 {
+							messages := tc.framer.Frame(buffer[0:byteCount])
+							for _, message := range messages {
+								slog.Debug("tcp-client message", "bytes", message)
+							}
+						}
 					}
 				}
 
diff --git a/tcp-server.go b/tcp-server.go
index 0ee6575..f32d160 100644
--- a/tcp-server.go
+++ b/tcp-server.go
@@ -5,11 +5,14 @@ import (
 	"fmt"
 	"log/slog"
 	"net"
+
+	"github.com/jwetzell/showbridge-go/internals/framing"
 )
 
 type TCPServer struct {
-	config ModuleConfig
-	Port   uint16
+	config        ModuleConfig
+	Port          uint16
+	framingMethod string
 }
 
 func init() {
@@ -28,7 +31,18 @@ func init() {
 				return nil, fmt.Errorf("tcp server port must be uint16")
 			}
 
-			return TCPServer{Port: uint16(portNum), config: config}, nil
+			framingMethod, ok := params["framing"]
+			if !ok {
+				return nil, fmt.Errorf("tcp server requires a framing method")
+			}
+
+			framingMethodString, ok := framingMethod.(string)
+
+			if !ok {
+				return nil, fmt.Errorf("tcp framing method must be a string")
+			}
+
+			return TCPServer{framingMethod: framingMethodString, Port: uint16(portNum), config: config}, nil
 		},
 	})
 }
@@ -44,6 +58,17 @@ func (ts TCPServer) Type() string {
 func (ts TCPServer) HandleClient(ctx context.Context, client net.Conn) {
 	slog.Info("handling connection", "remoteAddr", client.RemoteAddr().String())
 
+	var framer framing.Framer
+
+	switch ts.framingMethod {
+	case "LF":
+		framer = framing.NewByteSeparatorFramer([]byte{'\n'})
+	case "CR":
+		framer = framing.NewByteSeparatorFramer([]byte{'\r'})
+	case "CRLF":
+		framer = framing.NewByteSeparatorFramer([]byte{'\r', '\n'})
+	}
+
 	buffer := make([]byte, 1024)
 	for {
 		select {
@@ -58,9 +83,13 @@ func (ts TCPServer) HandleClient(ctx context.Context, client net.Conn) {
 				}
 				return
 			}
-
-			if byteCount > 0 {
-				slog.Info(string(buffer[0:byteCount]))
+			if framer != nil {
+				if byteCount > 0 {
+					messages := framer.Frame(buffer[0:byteCount])
+					for _, message := range messages {
+						slog.Debug("tcp-server message", "bytes", message)
+					}
+				}
 			}
 		}