Implement Frames

I feel like that gets a bit too abstract, too quickly.

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2026 m
+Copyright (c) 2026 Michael Smith
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and 
 associated documentation files (the "Software"), to deal in the Software without restriction, including 

README.md

@@ -1,3 +1,5 @@
 # go-agwpe
 
-Provides a client implementation of the AGWPE protocol for Go
+Provides a client implementation of the AGWPE protocol for Go.
+
+Ported in part from https://github.com/mfncooper/pyham_pe.

agwpe.go

@@ -0,0 +1,66 @@
+package agwpe
+
+import (
+	"fmt"
+	"net"
+	"sync"
+	"time"
+)
+
+type Config struct {
+	Timeout time.Duration
+}
+
+type Option func(*Config)
+
+type PacketEngine struct {
+	address string
+	cfg     Config
+	Ready   bool
+	conn    net.Conn
+	mu      sync.Mutex
+}
+
+func WithTimeout(d time.Duration) Option {
+	return func(c *Config) {
+		c.Timeout = d
+	}
+}
+
+func NewPacketEngine(address string, opts ...Option) (*PacketEngine, error) {
+	defaultCfg := Config{
+		Timeout: 5 * time.Second,
+	}
+
+	for _, opt := range opts {
+		opt(&defaultCfg)
+	}
+
+	return &PacketEngine{
+		address: address,
+		cfg:     defaultCfg,
+		Ready:   false,
+	}, nil
+}
+
+func (pe *PacketEngine) Connect() error {
+	conn, err := net.DialTimeout("tcp", pe.address, pe.cfg.Timeout)
+	if err != nil {
+		return err
+	}
+	pe.conn = conn
+	fmt.Println("Connected to", pe.address)
+
+	return nil
+}
+
+func (pe *PacketEngine) Disconnect() error {
+	if pe.conn == nil {
+		return fmt.Errorf("Not connected!")
+	}
+	pe.conn.Close()
+	pe.conn = nil
+	fmt.Println("Disonnected from", pe.address)
+
+	return nil
+}

agwpe_test.go

@@ -0,0 +1,79 @@
+package agwpe
+
+import (
+	"net"
+	"testing"
+	"time"
+)
+
+// NOTE(m): Use more table-driven-tests? At the moment this feels less abstract.
+
+func TestNewPacketEngine(t *testing.T) {
+	// Default configuration
+	engine, err := NewPacketEngine("localhost:1234")
+	if err != nil {
+		t.Errorf("Did not expect error: %v", err)
+	}
+	if engine.cfg.Timeout != 5*time.Second {
+		t.Errorf("Expected 5 second timeout, got %v", engine.cfg.Timeout)
+	}
+	if engine.Ready {
+		t.Error("Expected engine that is not ready")
+	}
+
+	// Custom timeout
+	engine, err = NewPacketEngine("localhost:1234", WithTimeout(30*time.Second))
+	if err != nil {
+		t.Errorf("Did not expect error: %v", err)
+	}
+	if engine.cfg.Timeout != 30*time.Second {
+		t.Errorf("Expected 30 second timeout, got %v", engine.cfg.Timeout)
+	}
+}
+
+func TestPacketEngine_Connect(t *testing.T) {
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer listener.Close()
+	serverAddr := listener.Addr().String()
+
+	// Successful connect
+	engine, _ := NewPacketEngine(serverAddr)
+	err = engine.Connect()
+	if err != nil {
+		t.Errorf("Did not expect error: %v", err)
+	}
+
+	// Invalid address
+	engine, _ = NewPacketEngine("invalid-address")
+	err = engine.Connect()
+	if err == nil {
+		t.Error("Expected an error")
+	}
+}
+
+func TestPacketEngine_Disconnect(t *testing.T) {
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer listener.Close()
+	serverAddr := listener.Addr().String()
+
+	engine, _ := NewPacketEngine(serverAddr)
+	engine.Connect()
+
+	// Disconnect connected engine
+	err = engine.Disconnect()
+	if err != nil {
+		t.Errorf("Did not expect error: %v", err)
+	}
+
+	// Call to Disconnect() on disconnected packet engine should return an error
+	err = engine.Disconnect()
+	if err == nil {
+		t.Error("Expected an error")
+	}
+}

frame.go

@@ -0,0 +1,35 @@
+package agwpe
+
+import (
+	"encoding/binary"
+)
+
+type FrameHeader struct {
+	Port      byte
+	Reserved0 [3]byte
+	DataKind  byte
+	Reserved1 byte
+	PID       byte
+	Reserved2 byte
+	CallFrom  [10]byte
+	CallTo    [10]byte
+	DataLen   uint32
+	User      [4]byte
+}
+
+func (f *FrameHeader) Serialize() []byte {
+	buf := make([]byte, 36)
+
+	buf[0] = f.Port
+	// Ignore reserved bytes 1 to 3
+	buf[4] = f.DataKind
+	// Ignore reserved byte 5
+	buf[6] = f.PID
+	// Ignore reserved byte 7
+	copy(buf[8:18], f.CallFrom[:])
+	copy(buf[18:28], f.CallTo[:])
+	binary.LittleEndian.PutUint32(buf[28:32], f.DataLen)
+	copy(buf[32:36], f.User[:])
+
+	return buf
+}

frame_test.go

@@ -0,0 +1,13 @@
+package agwpe
+
+import (
+	"testing"
+)
+
+func TestNewFrameHeader(t *testing.T) {
+
+}
+
+func TestFrameHeader_Serialize(t *testing.T) {
+
+}

go.mod

@@ -0,0 +1,3 @@
+module git.smith.eu/m/go-agwpe
+
+go 1.24.5