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// Copyright 2011 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.
// Network interface identification for Linux
package net
import (
"os"
"syscall"
"unsafe"
)
// 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 := syscall.NetlinkRIB(syscall.RTM_GETLINK, syscall.AF_UNSPEC)
if err != nil {
return nil, os.NewSyscallError("netlink rib", err)
}
msgs, err := syscall.ParseNetlinkMessage(tab)
if err != nil {
return nil, os.NewSyscallError("netlink message", err)
}
var ift []Interface
for _, m := range msgs {
switch m.Header.Type {
case syscall.NLMSG_DONE:
goto done
case syscall.RTM_NEWLINK:
ifim := (*syscall.IfInfomsg)(unsafe.Pointer(&m.Data[0]))
if ifindex == 0 || ifindex == int(ifim.Index) {
attrs, err := syscall.ParseNetlinkRouteAttr(&m)
if err != nil {
return nil, os.NewSyscallError("netlink routeattr", err)
}
ifi := newLink(ifim, attrs)
ift = append(ift, ifi)
}
}
}
done:
return ift, nil
}
func newLink(ifim *syscall.IfInfomsg, attrs []syscall.NetlinkRouteAttr) Interface {
ifi := Interface{Index: int(ifim.Index), Flags: linkFlags(ifim.Flags)}
for _, a := range attrs {
switch a.Attr.Type {
case syscall.IFLA_ADDRESS:
var nonzero bool
for _, b := range a.Value {
if b != 0 {
nonzero = true
}
}
if nonzero {
ifi.HardwareAddr = a.Value[:]
}
case syscall.IFLA_IFNAME:
ifi.Name = string(a.Value[:len(a.Value)-1])
case syscall.IFLA_MTU:
ifi.MTU = int(*(*uint32)(unsafe.Pointer(&a.Value[:4][0])))
}
}
return ifi
}
func linkFlags(rawFlags uint32) 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 ifindex is zero, interfaceAddrTable returns addresses
// for all network interfaces. Otherwise it returns addresses
// for a specific interface.
func interfaceAddrTable(ifindex int) ([]Addr, error) {
tab, err := syscall.NetlinkRIB(syscall.RTM_GETADDR, syscall.AF_UNSPEC)
if err != nil {
return nil, os.NewSyscallError("netlink rib", err)
}
msgs, err := syscall.ParseNetlinkMessage(tab)
if err != nil {
return nil, os.NewSyscallError("netlink message", err)
}
ifat, err := addrTable(msgs, ifindex)
if err != nil {
return nil, err
}
return ifat, nil
}
func addrTable(msgs []syscall.NetlinkMessage, ifindex int) ([]Addr, error) {
var ifat []Addr
for _, m := range msgs {
switch m.Header.Type {
case syscall.NLMSG_DONE:
goto done
case syscall.RTM_NEWADDR:
ifam := (*syscall.IfAddrmsg)(unsafe.Pointer(&m.Data[0]))
if ifindex == 0 || ifindex == int(ifam.Index) {
attrs, err := syscall.ParseNetlinkRouteAttr(&m)
if err != nil {
return nil, os.NewSyscallError("netlink routeattr", err)
}
ifat = append(ifat, newAddr(attrs, int(ifam.Family), int(ifam.Prefixlen)))
}
}
}
done:
return ifat, nil
}
func newAddr(attrs []syscall.NetlinkRouteAttr, family, pfxlen int) Addr {
ifa := &IPNet{}
for _, a := range attrs {
switch a.Attr.Type {
case syscall.IFA_ADDRESS:
switch family {
case syscall.AF_INET:
ifa.IP = IPv4(a.Value[0], a.Value[1], a.Value[2], a.Value[3])
ifa.Mask = CIDRMask(pfxlen, 8*IPv4len)
case syscall.AF_INET6:
ifa.IP = make(IP, IPv6len)
copy(ifa.IP, a.Value[:])
ifa.Mask = CIDRMask(pfxlen, 8*IPv6len)
}
}
}
return ifa
}
// If the ifindex is zero, interfaceMulticastAddrTable returns
// addresses for all network interfaces. Otherwise it returns
// addresses for a specific interface.
func interfaceMulticastAddrTable(ifindex int) ([]Addr, error) {
var (
err error
ifi *Interface
)
if ifindex > 0 {
ifi, err = InterfaceByIndex(ifindex)
if err != nil {
return nil, err
}
}
ifmat4 := parseProcNetIGMP("/proc/net/igmp", ifi)
ifmat6 := parseProcNetIGMP6("/proc/net/igmp6", ifi)
return append(ifmat4, ifmat6...), nil
}
func parseProcNetIGMP(path string, ifi *Interface) []Addr {
fd, err := open(path)
if err != nil {
return nil
}
defer fd.close()
var (
ifmat []Addr
name string
)
fd.readLine() // skip first line
b := make([]byte, IPv4len)
for l, ok := fd.readLine(); ok; l, ok = fd.readLine() {
f := splitAtBytes(l, " :\r\t\n")
if len(f) < 4 {
continue
}
switch {
case l[0] != ' ' && l[0] != '\t': // new interface line
name = f[1]
case len(f[0]) == 8:
if ifi == nil || name == ifi.Name {
// The Linux kernel puts the IP
// address in /proc/net/igmp in native
// endianness.
for i := 0; i+1 < len(f[0]); i += 2 {
b[i/2], _ = xtoi2(f[0][i:i+2], 0)
}
i := *(*uint32)(unsafe.Pointer(&b[:4][0]))
ifma := IPAddr{IP: IPv4(byte(i>>24), byte(i>>16), byte(i>>8), byte(i))}
ifmat = append(ifmat, ifma.toAddr())
}
}
}
return ifmat
}
func parseProcNetIGMP6(path string, ifi *Interface) []Addr {
fd, err := open(path)
if err != nil {
return nil
}
defer fd.close()
var ifmat []Addr
b := make([]byte, IPv6len)
for l, ok := fd.readLine(); ok; l, ok = fd.readLine() {
f := splitAtBytes(l, " \r\t\n")
if len(f) < 6 {
continue
}
if ifi == nil || f[1] == ifi.Name {
for i := 0; i+1 < len(f[2]); i += 2 {
b[i/2], _ = xtoi2(f[2][i:i+2], 0)
}
ifma := IPAddr{IP: IP{b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7], b[8], b[9], b[10], b[11], b[12], b[13], b[14], b[15]}}
ifmat = append(ifmat, ifma.toAddr())
}
}
return ifmat
}
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