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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package net
import (
"internal/poll"
"internal/syscall/unix"
"syscall"
"unsafe"
)
type rawSockaddrDatalink struct {
Len uint8
Family uint8
Index uint16
Type uint8
Nlen uint8
Alen uint8
Slen uint8
Data [120]byte
}
type ifreq struct {
Name [16]uint8
Ifru [16]byte
}
const _KINFO_RT_IFLIST = (0x1 << 8) | 3 | (1 << 30)
const _RTAX_NETMASK = 2
const _RTAX_IFA = 5
const _RTAX_MAX = 8
func getIfList() ([]byte, error) {
needed, err := syscall.Getkerninfo(_KINFO_RT_IFLIST, 0, 0, 0)
if err != nil {
return nil, err
}
tab := make([]byte, needed)
_, err = syscall.Getkerninfo(_KINFO_RT_IFLIST, uintptr(unsafe.Pointer(&tab[0])), uintptr(unsafe.Pointer(&needed)), 0)
if err != nil {
return nil, err
}
return tab[:needed], nil
}
// If the ifindex is zero, interfaceTable returns mappings of all
// network interfaces. Otherwise it returns a mapping of a specific
// interface.
func interfaceTable(ifindex int) ([]Interface, error) {
tab, err := getIfList()
if err != nil {
return nil, err
}
sock, err := sysSocket(syscall.AF_INET, syscall.SOCK_DGRAM, 0)
if err != nil {
return nil, err
}
defer poll.CloseFunc(sock)
var ift []Interface
for len(tab) > 0 {
ifm := (*syscall.IfMsgHdr)(unsafe.Pointer(&tab[0]))
if ifm.Msglen == 0 {
break
}
if ifm.Type == syscall.RTM_IFINFO {
if ifindex == 0 || ifindex == int(ifm.Index) {
sdl := (*rawSockaddrDatalink)(unsafe.Pointer(&tab[unsafe.Sizeof(syscall.IfMsgHdr)]))
ifi := &Interface{Index: int(ifm.Index), Flags: linkFlags(ifm.Flags)}
ifi.Name = string(sdl.Data[:sdl.Nlen])
ifi.HardwareAddr = sdl.Data[sdl.Nlen : sdl.Nlen+sdl.Alen]
// Retrieve MTU
ifr := &ifreq{}
copy(ifr.Name[:], ifi.Name)
err = unix.Ioctl(sock, syscall.SIOCGIFMTU, unsafe.Pointer(ifr))
if err != nil {
return nil, err
}
ifi.MTU = int(ifr.Ifru[0])<<24 | int(ifr.Ifru[1])<<16 | int(ifr.Ifru[2])<<8 | int(ifr.Ifru[3])
ift = append(ift, *ifi)
if ifindex == int(ifm.Index) {
break
}
}
}
tab = tab[ifm.Msglen:]
}
return ift, nil
}
func linkFlags(rawFlags int32) Flags {
var f Flags
if rawFlags&syscall.IFF_UP != 0 {
f |= FlagUp
}
if rawFlags&syscall.IFF_BROADCAST != 0 {
f |= FlagBroadcast
}
if rawFlags&syscall.IFF_LOOPBACK != 0 {
f |= FlagLoopback
}
if rawFlags&syscall.IFF_POINTOPOINT != 0 {
f |= FlagPointToPoint
}
if rawFlags&syscall.IFF_MULTICAST != 0 {
f |= FlagMulticast
}
return f
}
// If the ifi is nil, interfaceAddrTable returns addresses for all
// network interfaces. Otherwise it returns addresses for a specific
// interface.
func interfaceAddrTable(ifi *Interface) ([]Addr, error) {
tab, err := getIfList()
if err != nil {
return nil, err
}
var ifat []Addr
for len(tab) > 0 {
ifm := (*syscall.IfMsgHdr)(unsafe.Pointer(&tab[0]))
if ifm.Msglen == 0 {
break
}
if ifm.Type == syscall.RTM_NEWADDR {
if ifi == nil || ifi.Index == int(ifm.Index) {
mask := ifm.Addrs
off := uint(unsafe.Sizeof(syscall.IfMsgHdr))
var iprsa, nmrsa *syscall.RawSockaddr
for i := uint(0); i < _RTAX_MAX; i++ {
if mask&(1<<i) == 0 {
continue
}
rsa := (*syscall.RawSockaddr)(unsafe.Pointer(&tab[off]))
if i == _RTAX_NETMASK {
nmrsa = rsa
}
if i == _RTAX_IFA {
iprsa = rsa
}
off += (uint(rsa.Len) + 3) &^ 3
}
if iprsa != nil && nmrsa != nil {
var mask IPMask
var ip IP
switch iprsa.Family {
case syscall.AF_INET:
ipsa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(iprsa))
nmsa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(nmrsa))
ip = IPv4(ipsa.Addr[0], ipsa.Addr[1], ipsa.Addr[2], ipsa.Addr[3])
mask = IPv4Mask(nmsa.Addr[0], nmsa.Addr[1], nmsa.Addr[2], nmsa.Addr[3])
case syscall.AF_INET6:
ipsa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(iprsa))
nmsa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(nmrsa))
ip = make(IP, IPv6len)
copy(ip, ipsa.Addr[:])
mask = make(IPMask, IPv6len)
copy(mask, nmsa.Addr[:])
}
ifa := &IPNet{IP: ip, Mask: mask}
ifat = append(ifat, ifa)
}
}
}
tab = tab[ifm.Msglen:]
}
return ifat, nil
}
// interfaceMulticastAddrTable returns addresses for a specific
// interface.
func interfaceMulticastAddrTable(ifi *Interface) ([]Addr, error) {
return nil, nil
}
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