From 8e0f25abe914fa9824e22200aee9a78edf21eb63 Mon Sep 17 00:00:00 2001
From: Joel Wetzell <git@jwetzell.com>
Date: Tue, 18 Nov 2025 21:30:06 -0600
Subject: [PATCH] add SLIP framing

---
 internals/framing/slip.go | 52 +++++++++++++++++++++++++++++++++++++++
 tcp-client.go             |  2 ++
 tcp-server.go             |  2 ++
 3 files changed, 56 insertions(+)
 create mode 100644 internals/framing/slip.go

diff --git a/internals/framing/slip.go b/internals/framing/slip.go
new file mode 100644
index 0000000..607d94f
--- /dev/null
+++ b/internals/framing/slip.go
@@ -0,0 +1,52 @@
+package framing
+
+type SlipFramer struct {
+	buffer []byte
+}
+
+func NewSlipFramer() *SlipFramer {
+	return &SlipFramer{buffer: []byte{}}
+}
+
+func (sf *SlipFramer) Frame(data []byte) [][]byte {
+	messages := [][]byte{}
+	END := byte(0xc0)
+	ESC := byte(0xdb)
+	ESC_END := byte(0xdc)
+	ESC_ESC := byte(0xdd)
+
+	escapeNext := false
+	for _, packetByte := range data {
+
+		if packetByte == ESC {
+			escapeNext = true
+			continue
+		}
+
+		if escapeNext {
+			if packetByte == ESC_END {
+				sf.buffer = append(sf.buffer, END)
+			} else if packetByte == ESC_ESC {
+				sf.buffer = append(sf.buffer, ESC)
+			}
+			escapeNext = false
+		} else if packetByte == END {
+			if len(sf.buffer) == 0 {
+				// opening END byte, can discard
+				continue
+			} else {
+				message := sf.buffer
+				messages = append(messages, message)
+			}
+			sf.buffer = []byte{}
+		} else {
+			sf.buffer = append(sf.buffer, packetByte)
+		}
+	}
+
+	return messages
+}
+
+func (sf *SlipFramer) Clear() {
+	sf.buffer = []byte{}
+}
diff --git a/tcp-client.go b/tcp-client.go
index e1f18a6..7bd4720 100644
--- a/tcp-client.go
+++ b/tcp-client.go
@@ -65,6 +65,8 @@ func init() {
 				framer = framing.NewByteSeparatorFramer([]byte{'\n'})
 			case "CRLF":
 				framer = framing.NewByteSeparatorFramer([]byte{'\r', '\n'})
+			case "SLIP":
+				framer = framing.NewSlipFramer()
 			default:
 				return nil, fmt.Errorf("unknown framing method: %s", framingMethodString)
 			}
diff --git a/tcp-server.go b/tcp-server.go
index f32d160..3fc6385 100644
--- a/tcp-server.go
+++ b/tcp-server.go
@@ -67,6 +67,8 @@ func (ts TCPServer) HandleClient(ctx context.Context, client net.Conn) {
 		framer = framing.NewByteSeparatorFramer([]byte{'\r'})
 	case "CRLF":
 		framer = framing.NewByteSeparatorFramer([]byte{'\r', '\n'})
+	case "SLIP":
+		framer = framing.NewSlipFramer()
 	}
 
 	buffer := make([]byte, 1024)