mirror of
https://github.com/soypat/lneto.git
synced 2026-08-05 15:33:41 +00:00
soypat
59 lines
1.2 KiB
Go
59 lines
1.2 KiB
Go
package internal
|
|
|
|
import (
|
|
"encoding/binary"
|
|
"errors"
|
|
)
|
|
|
|
var (
|
|
errUnsupportedIP = errors.New("unsupported IP version")
|
|
errInvalidIPVersionToSetAddr = errors.New("invalid ip version to setDstAddr")
|
|
)
|
|
|
|
func GetIPAddr(buf []byte) (src, dst []byte, id, ipEndOff uint16, err error) {
|
|
b0 := buf[0]
|
|
version := b0 >> 4
|
|
switch version {
|
|
case 4:
|
|
ihl := b0 & 0xf
|
|
ipEndOff = 4 * uint16(ihl)
|
|
id = binary.BigEndian.Uint16(buf[4:6])
|
|
src = buf[12:16]
|
|
dst = buf[16:20]
|
|
case 6:
|
|
src = buf[8:24]
|
|
dst = buf[24:40]
|
|
ipEndOff = 40
|
|
default:
|
|
err = errUnsupportedIP
|
|
}
|
|
return src, dst, id, ipEndOff, err
|
|
}
|
|
|
|
func SetIPAddrs(buf []byte, id uint16, src, dst []byte) (err error) {
|
|
var dstaddr, srcaddr []byte
|
|
version := buf[0] >> 4
|
|
switch version {
|
|
case 4:
|
|
srcaddr = buf[12:16]
|
|
dstaddr = buf[16:20]
|
|
if id > 0 {
|
|
binary.BigEndian.PutUint16(buf[4:6], id)
|
|
}
|
|
case 6:
|
|
srcaddr = buf[8:24]
|
|
dstaddr = buf[24:40]
|
|
default:
|
|
return errUnsupportedIP
|
|
}
|
|
if src != nil && len(srcaddr) != len(src) {
|
|
return errors.New("mismatched length of ip src addr")
|
|
}
|
|
if dst != nil && len(dstaddr) != len(dst) {
|
|
return errors.New("mismatched length of ip dst addr")
|
|
}
|
|
copy(srcaddr, src)
|
|
copy(dstaddr, dst)
|
|
return nil
|
|
}
|