// 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[syscall.SizeofIfMsghdr])) 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_RUNNING != 0 { f |= FlagRunning } 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(syscall.SizeofIfMsghdr) var iprsa, nmrsa *syscall.RawSockaddr for i := uint(0); i < _RTAX_MAX; i++ { if mask&(1<