-
Notifications
You must be signed in to change notification settings - Fork 0
/
common.go
74 lines (66 loc) · 1.46 KB
/
common.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
package bacnet
import (
"errors"
"net"
)
const (
MAX_BACNET_FRAME_LEN = 1476
)
// VLC Header constants
const (
VLC_TYPE_IP byte = 0x81
VLC_FUNCTION_UNICAST_NPDU byte = 0x0a
)
// NPDU header constant
const (
NPDU_VERSION_ASHRAE_135_1995 byte = 0x01
NPDU_FLAG_EXPECTING_RESPONSE byte = 0x04
)
// APDU Server Choice constants
const (
SERVER_CHOICE_READ_PROPERTY byte = 0x0c
)
var (
errBACNetPacketTooShort error = errors.New("BACNet packet too short")
errInvalidPacket error = errors.New("Invalid BACNet packet")
errNotBACNet error = errors.New("Not a BACNet packet")
)
func SendVLC(c net.Conn, payload []byte) error {
if len(payload) > 1472 {
return errors.New("payload too long")
}
vlc := VLC{
Type: VLC_TYPE_IP,
Function: VLC_FUNCTION_UNICAST_NPDU,
Length: 4 + uint16(len(payload)),
}
b, _ := vlc.Marshal()
b = append(b, payload...)
if _, err := c.Write(b); err != nil {
return err
}
return nil
}
func ReadVLC(c net.Conn) (vlc *VLC, npdu *NPDU, apdu *APDU, leftovers []byte, err error, isBACNet bool) {
b := make([]byte, MAX_BACNET_FRAME_LEN)
n, err := c.Read(b)
if err != nil {
return
}
b = b[0:n]
leftovers = b
vlc = new(VLC)
if leftovers, err = vlc.Unmarshal(leftovers); err != nil {
return
}
isBACNet = true
npdu = new(NPDU)
if leftovers, err = npdu.Unmarshal(leftovers); err != nil {
return
}
apdu = new(APDU)
if leftovers, err = apdu.Unmarshal(leftovers); err != nil {
return
}
return
}