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118 lines
2.3 KiB
Go
118 lines
2.3 KiB
Go
package protocol
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"git.noahlan.cn/noahlan/nnet/packet"
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"git.noahlan.cn/noahlan/ntool/nlog"
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)
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type TCPPackerOption func(*TCPPacker)
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type TCPPacker struct {
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buf *bytes.Buffer
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header *TCPHeader
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size int // 最近一次读取的 body size
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byteOrder binary.ByteOrder
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}
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const (
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tcpHeadLength = 2 + 2 + 2
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tcpMaxPacketSize = 64 * 1024
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)
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func NewTCPPacker(byteOrder binary.ByteOrder) *TCPPacker {
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p := &TCPPacker{
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buf: bytes.NewBuffer(nil),
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byteOrder: byteOrder,
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}
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p.resetFlags()
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return p
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}
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func (d *TCPPacker) resetFlags() {
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d.header = nil
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d.size = -1
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}
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func (d *TCPPacker) Pack(header interface{}, data []byte) ([]byte, error) {
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tcpHeader, ok := header.(*TCPHeader)
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if !ok {
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return nil, packet.ErrWrongPacketType
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}
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bs := make([]byte, 8)
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d.byteOrder.PutUint16(bs[0:2], tcpHeader.TransactionIdentifier)
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d.byteOrder.PutUint16(bs[2:4], tcpHeader.ProtocolIdentifier)
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d.byteOrder.PutUint16(bs[4:6], uint16(2+len(data)))
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bs[6] = tcpHeader.Address
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bs[7] = tcpHeader.Function
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bs = append(bs, data...)
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return bs, nil
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}
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func (d *TCPPacker) Unpack(data []byte) ([]packet.IPacket, error) {
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d.buf.Write(data)
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nlog.Debugf("接收TCP数据: %x", data)
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var (
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packets []packet.IPacket
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err error
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)
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if d.buf.Len() < 9 {
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return packets, fmt.Errorf("TCP Frame error: packet less than 9 bytes")
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}
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if d.size < 0 {
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if err = d.readHeader(); err != nil {
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return nil, err
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}
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}
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for (d.size - 2) <= d.buf.Len() {
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p := NewTCPPacket()
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p.TCPHeader = d.header
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p.Data = d.buf.Next(d.size - 2)
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packets = append(packets, p)
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if d.buf.Len() < (tcpHeadLength + 2) {
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d.resetFlags()
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break
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}
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if err = d.readHeader(); err != nil {
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return packets, err
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}
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}
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if packets == nil || len(packets) == 0 {
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d.resetFlags()
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d.buf.Reset()
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}
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return packets, err
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}
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func (d *TCPPacker) readHeader() error {
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header := d.buf.Next(tcpHeadLength + 2)
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d.header = &TCPHeader{
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TransactionIdentifier: d.byteOrder.Uint16(header[0:2]),
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ProtocolIdentifier: d.byteOrder.Uint16(header[2:4]),
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Length: d.byteOrder.Uint16(header[4:6]),
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ModbusHeader: ModbusHeader{
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Address: header[6],
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Function: header[7],
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},
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}
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d.size = int(d.header.Length)
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// 最大包限定
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if d.size > tcpMaxPacketSize {
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return packet.ErrPacketSizeExceed
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}
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return nil
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}
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