implement messages

cmd/cmd/speeddaemon/main.go

@@ -0,0 +1,5 @@
+package main
+
+func main() {
+
+}

cmd/cmd/speeddaemon/message.go

@@ -0,0 +1,108 @@
+package main
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"time"
+)
+
+const (
+	errorHeader         byte = 0x10
+	plateHeader         byte = 0x20
+	ticketHeader        byte = 0x21
+	wantHeartbeatHeader byte = 0x40
+	heartbeatHeader     byte = 0x41
+	amCameraHeader      byte = 0x80
+	amDispatcherHeader  byte = 0x81
+)
+
+func encodeErrorMessage(msg string) []byte {
+	b := bytes.NewBuffer([]byte{errorHeader})
+	b.WriteByte(byte(len(msg)))
+	b.Write([]byte(msg))
+	return b.Bytes()
+}
+
+type plateMessage struct {
+	plate     string
+	timestamp time.Time
+}
+
+func decodePlateMessage(data []byte) (*plateMessage, error) {
+	if data[0] != plateHeader {
+		return nil, fmt.Errorf("attempted to decode plate message with header %0x", data[0])
+	}
+
+	pl := int(data[1])
+	plate := string(data[2 : 2+pl])
+	ts32 := binary.BigEndian.Uint32(data[2+pl:])
+
+	return &plateMessage{
+		plate:     plate,
+		timestamp: time.Unix(int64(ts32), 0),
+	}, nil
+}
+
+type ticketMessage struct {
+	plate        string
+	road         uint16
+	mileOne      uint16
+	timestampOne uint32
+	mileTwo      uint16
+	timestampTwo uint32
+	speed        uint16
+}
+
+func encodeTicketMessage(data []byte) (*ticketMessage, error) {
+	panic("unimplemented")
+}
+
+type wantHeartbeatMessage uint32
+
+func decodeWantHeartbeatMessage(data []byte) (*wantHeartbeatMessage, error) {
+	if data[0] != wantHeartbeatHeader {
+		return nil, fmt.Errorf("attempted to decode wantHearbeatMessage with header %0x", data[0])
+	}
+	d := wantHeartbeatMessage(binary.BigEndian.Uint32(data[1:]))
+	return &d, nil
+}
+
+func encodeHeartbeat() []byte {
+	return []byte{heartbeatHeader}
+}
+
+type amCameraMessage struct {
+	road, mile, limit uint16
+}
+
+func decodeAmCameraMessage(data []byte) (*amCameraMessage, error) {
+	if data[0] != amCameraHeader {
+		return nil, fmt.Errorf("attempted to decode amCameraMessage with header %0x", data[0])
+	}
+	return &amCameraMessage{
+		road:  binary.BigEndian.Uint16(data[1:3]),
+		mile:  binary.BigEndian.Uint16(data[3:5]),
+		limit: binary.BigEndian.Uint16(data[5:]),
+	}, nil
+}
+
+type amDispatcherMessage struct {
+	numroads byte
+	roads    []uint16
+}
+
+func decodeAmDispatcherMessage(data []byte) (*amDispatcherMessage, error) {
+	if data[0] != amDispatcherHeader {
+		return nil, fmt.Errorf("attempted to decode amDispatcherMessage with header %0x", data[0])
+	}
+	var roads []uint16
+	for i, j := 0, 2; i < int(data[1]); i++ {
+		roads = append(roads, binary.BigEndian.Uint16(data[j:j+2]))
+		j += 2
+	}
+	return &amDispatcherMessage{
+		data[1],
+		roads,
+	}, nil
+}

cmd/cmd/speeddaemon/message_test.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"testing"
+	"time"
+)
+
+func TestPlateMessage(t *testing.T) {
+	data := []byte{0x20, 0x04, 0x55, 0x4e, 0x31, 0x58, 0x00, 0x00, 0x03, 0xe8}
+	p, err := decodePlateMessage(data)
+	if err != nil {
+		t.Error(err)
+	}
+	if p.plate != "UN1X" {
+		t.Error("plate wrong")
+	}
+	if p.timestamp != time.Unix(0x000003e8, 0) {
+		t.Error("timestamp wrong")
+	}
+}
+
+func TestWantHeartbeatMessage(t *testing.T) {
+	data := []byte{0x40, 0x00, 0x00, 0x00, 0x0a}
+	h, err := decodeWantHeartbeatMessage(data)
+	if err != nil {
+		t.Error(err)
+	}
+	if *h != wantHeartbeatMessage(10) {
+		t.Error("Wrong duration")
+	}
+}
+
+func TestAmCameraMessage(t *testing.T) {
+	data := []byte{0x80, 0x00, 0x42, 0x00, 0x64, 0x00, 0x3c}
+	m, err := decodeAmCameraMessage(data)
+	if err != nil {
+		t.Error(err)
+	}
+	if m.road != 66 {
+		t.Error("wrong road")
+	}
+	if m.mile != 100 {
+		t.Error("wrong mile")
+	}
+	if m.limit != 60 {
+		t.Error("wrong limit")
+	}
+}
+
+func TestAmDispatcherMessage(t *testing.T) {
+	data := []byte{0x81, 0x01, 0x00, 0x42}
+	m, err := decodeAmDispatcherMessage(data)
+	if err != nil {
+		t.Error(err)
+	}
+	if m.numroads != 1 {
+		t.Error("wrong numroads")
+	}
+	if len(m.roads) != 1 {
+		t.Error("wrong length of roads")
+	}
+	if m.roads[0] != 66 {
+		t.Error("wrong roads[0]")
+	}
+}
+
+func TestAmDispatcherMessageLong(t *testing.T) {
+	data := []byte{0x81, 0x03, 0x00, 0x42, 0x01, 0x70, 0x13, 0x88}
+	m, err := decodeAmDispatcherMessage(data)
+	if err != nil {
+		t.Error(err)
+	}
+	if m.numroads != 3 {
+		t.Error("wrong numroads")
+	}
+	if len(m.roads) != 3 {
+		t.Error("wrong length of roads")
+	}
+	if m.roads[0] != 66 {
+		t.Error("wrong roads[0]")
+	}
+	if m.roads[1] != 368 {
+		t.Error("wrong roads[0]")
+	}
+	if m.roads[2] != 5000 {
+		t.Error("wrong roads[0]")
+	}
+}