water/waterutil/tap.go

48 lines
1.2 KiB
Go

package waterutil
import (
"net"
)
type Tagging int
// Indicating whether/how a MAC frame is tagged. The value is number of bytes taken by tagging.
const (
NotTagged Tagging = 0
Tagged Tagging = 4
DoubleTagged Tagging = 8
)
func MACDestination(macFrame []byte) net.HardwareAddr {
return net.HardwareAddr(macFrame[:6])
}
func MACSource(macFrame []byte) net.HardwareAddr {
return net.HardwareAddr(macFrame[6:12])
}
func MACTagging(macFrame []byte) Tagging {
if macFrame[12] == 0x81 && macFrame[13] == 0x00 {
return Tagged
} else if macFrame[12] == 0x88 && macFrame[13] == 0xa8 {
return DoubleTagged
}
return NotTagged
}
func MACEthertype(macFrame []byte) Ethertype {
ethertypePos := 12 + MACTagging(macFrame)
return Ethertype{macFrame[ethertypePos], macFrame[ethertypePos+1]}
}
func MACPayload(macFrame []byte) []byte {
return macFrame[12+MACTagging(macFrame)+2:]
}
func IsBroadcast(addr net.HardwareAddr) bool {
return addr[0] == 0xff && addr[1] == 0xff && addr[2] == 0xff && addr[3] == 0xff && addr[4] == 0xff && addr[5] == 0xff
}
func IsIPv4Multicast(addr net.HardwareAddr) bool {
return addr[0] == 0x01 && addr[1] == 0x00 && addr[2] == 0x5e
}