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origdest_linux.go
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origdest_linux.go
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// +build linux
package markedconn
import (
"fmt"
"net"
"syscall"
"unsafe"
)
const (
sockOptOriginalDst = 80
)
type sockaddr4 struct {
family uint16
data [14]byte
}
type sockaddr6 struct {
family uint16
port [2]byte
flowInfo [4]byte //nolint
ip [16]byte
scopeID [4]byte //nolint
}
type origDest func(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err syscall.Errno)
func getOriginalDestPlatform(rawConn passFD, v4Proto bool) (net.IP, int, *PlatformData, error) {
return getOriginalDestInternal(rawConn, v4Proto, syscall.Syscall6)
}
func getOriginalDestInternal(rawConn passFD, v4Proto bool, getOrigDest origDest) (net.IP, int, *PlatformData, error) { // nolint interfacer{
var getsockopt func(fd uintptr)
var netIP net.IP
var port int
var err error
getsockopt4 := func(fd uintptr) {
var addr sockaddr4
size := uint32(unsafe.Sizeof(addr))
_, _, e1 := getOrigDest(syscall.SYS_GETSOCKOPT, uintptr(fd), uintptr(syscall.SOL_IP), uintptr(sockOptOriginalDst), uintptr(unsafe.Pointer(&addr)), uintptr(unsafe.Pointer(&size)), 0) //nolint
if e1 != 0 {
err = fmt.Errorf("Failed to get original destination: %s", e1)
return
}
if addr.family != syscall.AF_INET {
err = fmt.Errorf("invalid address family. Expected AF_INET")
return
}
netIP = addr.data[2:6]
port = int(addr.data[0])<<8 + int(addr.data[1])
}
getsockopt6 := func(fd uintptr) {
var addr sockaddr6
size := uint32(unsafe.Sizeof(addr))
_, _, e1 := getOrigDest(syscall.SYS_GETSOCKOPT, uintptr(fd), uintptr(syscall.SOL_IPV6), uintptr(sockOptOriginalDst), uintptr(unsafe.Pointer(&addr)), uintptr(unsafe.Pointer(&size)), 0) //nolint
if e1 != 0 {
err = fmt.Errorf("Failed to get original destination: %s", e1)
return
}
if addr.family != syscall.AF_INET6 {
err = fmt.Errorf("invalid address family. Expected AF_INET6")
return
}
netIP = addr.ip[:]
port = int(addr.port[0])<<8 + int(addr.port[1])
}
if v4Proto {
getsockopt = getsockopt4
} else {
getsockopt = getsockopt6
}
if err1 := rawConn.Control(getsockopt); err1 != nil {
return nil, 0, nil, fmt.Errorf("Failed to get original destination: %s", err)
}
if err != nil {
return nil, 0, nil, err
}
return netIP, port, nil, nil
}