feat(go): generate unique load simulator frames

2026-07-03 18:43:15 +08:00
parent 09f3e68891
commit 1cbe29c5fc
5 changed files with 340 additions and 12 deletions
--- a/go/vehicle-gateway/internal/loadsim/mutator.go
+++ b/go/vehicle-gateway/internal/loadsim/mutator.go
@@ -0,0 +1,166 @@
+package loadsim
+
+import (
+	"encoding/binary"
+	"fmt"
+	"time"
+)
+
+type FrameFactory struct {
+	protocol Protocol
+	base     []byte
+}
+
+func NewFrameFactory(protocol Protocol, template string) (*FrameFactory, error) {
+	base, err := FrameTemplate(protocol, template)
+	if err != nil {
+		return nil, err
+	}
+	return &FrameFactory{protocol: protocol, base: base}, nil
+}
+
+func (f *FrameFactory) Frame(connectionIndex int, frameIndex int64) ([]byte, error) {
+	switch f.protocol {
+	case ProtocolJT808:
+		return mutateJT808Frame(f.base, connectionIndex, frameIndex)
+	case ProtocolGB32960:
+		return mutateGB32960Frame(f.base, connectionIndex, frameIndex)
+	default:
+		out := append([]byte(nil), f.base...)
+		return out, nil
+	}
+}
+
+func mutateJT808Frame(base []byte, connectionIndex int, frameIndex int64) ([]byte, error) {
+	if len(base) < 2 || base[0] != 0x7e || base[len(base)-1] != 0x7e {
+		return nil, fmt.Errorf("jt808 template must include 0x7e delimiters")
+	}
+	payload, err := jt808Unescape(base[1 : len(base)-1])
+	if err != nil {
+		return nil, err
+	}
+	if len(payload) < 13 {
+		return nil, fmt.Errorf("jt808 template too short: %d", len(payload))
+	}
+	phone := fmt.Sprintf("%012d", 139000000000+connectionIndex%100000000)
+	copy(payload[4:10], encodeBCD(phone, 6))
+	binary.BigEndian.PutUint16(payload[10:12], uint16((int(frameIndex)+connectionIndex)%65536))
+	bodySize := int(binary.BigEndian.Uint16(payload[2:4]) & 0x03ff)
+	bodyStart := 12
+	if len(payload) >= bodyStart+bodySize+1 && bodySize >= 28 {
+		writeJT808Time(payload[bodyStart+22:bodyStart+28], time.Now().Add(time.Duration(frameIndex)*time.Second))
+	}
+	payload[len(payload)-1] = jt808Checksum(payload[:len(payload)-1])
+	escaped := jt808Escape(payload)
+	out := make([]byte, 0, len(escaped)+2)
+	out = append(out, 0x7e)
+	out = append(out, escaped...)
+	out = append(out, 0x7e)
+	return out, nil
+}
+
+func mutateGB32960Frame(base []byte, connectionIndex int, frameIndex int64) ([]byte, error) {
+	if len(base) < 25 || base[0] != '#' || base[1] != '#' {
+		return nil, fmt.Errorf("gb32960 template too short or missing start symbols")
+	}
+	frame := append([]byte(nil), base...)
+	vin := fmt.Sprintf("LNSIM%012d", connectionIndex%1000000000000)
+	copy(frame[4:21], []byte(vin[:17]))
+	bodyLen := int(binary.BigEndian.Uint16(frame[22:24]))
+	bodyStart := 24
+	if len(frame) >= bodyStart+bodyLen+1 && bodyLen >= 6 {
+		writeGB32960Time(frame[bodyStart:bodyStart+6], time.Now().Add(time.Duration(frameIndex)*time.Second))
+	}
+	frame[len(frame)-1] = gb32960BCC(frame[2 : len(frame)-1])
+	return frame, nil
+}
+
+func encodeBCD(value string, size int) []byte {
+	out := make([]byte, size)
+	if len(value)%2 == 1 {
+		value = "0" + value
+	}
+	if len(value) > size*2 {
+		value = value[len(value)-size*2:]
+	}
+	for len(value) < size*2 {
+		value = "0" + value
+	}
+	for i := 0; i < size; i++ {
+		out[i] = (value[i*2]-'0')<<4 | (value[i*2+1] - '0')
+	}
+	return out
+}
+
+func jt808Checksum(data []byte) byte {
+	var out byte
+	for _, value := range data {
+		out ^= value
+	}
+	return out
+}
+
+func jt808Escape(payload []byte) []byte {
+	out := make([]byte, 0, len(payload))
+	for _, value := range payload {
+		switch value {
+		case 0x7e:
+			out = append(out, 0x7d, 0x02)
+		case 0x7d:
+			out = append(out, 0x7d, 0x01)
+		default:
+			out = append(out, value)
+		}
+	}
+	return out
+}
+
+func jt808Unescape(payload []byte) ([]byte, error) {
+	out := make([]byte, 0, len(payload))
+	for i := 0; i < len(payload); i++ {
+		if payload[i] != 0x7d {
+			out = append(out, payload[i])
+			continue
+		}
+		if i+1 >= len(payload) {
+			return nil, fmt.Errorf("invalid jt808 escape at end")
+		}
+		i++
+		switch payload[i] {
+		case 0x01:
+			out = append(out, 0x7d)
+		case 0x02:
+			out = append(out, 0x7e)
+		default:
+			return nil, fmt.Errorf("invalid jt808 escape sequence 0x%02x", payload[i])
+		}
+	}
+	return out, nil
+}
+
+func writeJT808Time(out []byte, value time.Time) {
+	value = value.In(time.FixedZone("CST", 8*3600))
+	year := value.Year() % 100
+	parts := []int{year, int(value.Month()), value.Day(), value.Hour(), value.Minute(), value.Second()}
+	for i, part := range parts {
+		out[i] = byte(part/10)<<4 | byte(part%10)
+	}
+}
+
+func writeGB32960Time(out []byte, value time.Time) {
+	value = value.In(time.FixedZone("CST", 8*3600))
+	out[0] = byte(value.Year() % 100)
+	out[1] = byte(value.Month())
+	out[2] = byte(value.Day())
+	out[3] = byte(value.Hour())
+	out[4] = byte(value.Minute())
+	out[5] = byte(value.Second())
+}
+
+func gb32960BCC(data []byte) byte {
+	var out byte
+	for _, value := range data {
+		out ^= value
+	}
+	return out
+}