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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.
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
loop:
for _, m := range msgs {
switch m.Header.Type {
case syscall.NLMSG_DONE:
break loop
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)
}
ift = append(ift, *newLink(ifim, attrs))
if ifindex == int(ifim.Index) {
break loop
}
}
}
}
return ift, nil
}
const (
// See linux/if_arp.h.
// Note that Linux doesn't support IPv4 over IPv6 tunneling.
sysARPHardwareIPv4IPv4 = 768 // IPv4 over IPv4 tunneling
sysARPHardwareIPv6IPv6 = 769 // IPv6 over IPv6 tunneling
sysARPHardwareIPv6IPv4 = 776 // IPv6 over IPv4 tunneling
sysARPHardwareGREIPv4 = 778 // any over GRE over IPv4 tunneling
sysARPHardwareGREIPv6 = 823 // any over GRE over IPv6 tunneling
)
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:
// We never return any /32 or /128 IP address
// prefix on any IP tunnel interface as the
// hardware address.
switch len(a.Value) {
case IPv4len:
switch ifim.Type {
case sysARPHardwareIPv4IPv4, sysARPHardwareGREIPv4, sysARPHardwareIPv6IPv4:
continue
}
case IPv6len:
switch ifim.Type {
case sysARPHardwareIPv6IPv6, sysARPHardwareGREIPv6:
continue
}
}
var nonzero bool
for _, b := range a.Value {
if b != 0 {
nonzero = true
break
}
}
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 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 := 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)
}
var ift []Interface
if ifi == nil {
var err error
ift, err = interfaceTable(0)
if err != nil {
return nil, err
}
}
ifat, err := addrTable(ift, ifi, msgs)
if err != nil {
return nil, err
}
return ifat, nil
}
func addrTable(ift []Interface, ifi *Interface, msgs []syscall.NetlinkMessage) ([]Addr, error) {
var ifat []Addr
loop:
for _, m := range msgs {
switch m.Header.Type {
case syscall.NLMSG_DONE:
break loop
case syscall.RTM_NEWADDR:
ifam := (*syscall.IfAddrmsg)(unsafe.Pointer(&m.Data[0]))
if len(ift) != 0 || ifi.Index == int(ifam.Index) {
if len(ift) != 0 {
var err error
ifi, err = interfaceByIndex(ift, int(ifam.Index))
if err != nil {
return nil, err
}
}
attrs, err := syscall.ParseNetlinkRouteAttr(&m)
if err != nil {
return nil, os.NewSyscallError("netlink routeattr", err)
}
ifa := newAddr(ifi, ifam, attrs)
if ifa != nil {
ifat = append(ifat, ifa)
}
}
}
}
return ifat, nil
}
func newAddr(ifi *Interface, ifam *syscall.IfAddrmsg, attrs []syscall.NetlinkRouteAttr) Addr {
var ipPointToPoint bool
// Seems like we need to make sure whether the IP interface
// stack consists of IP point-to-point numbered or unnumbered
// addressing over point-to-point link encapsulation.
if ifi.Flags&FlagPointToPoint != 0 {
for _, a := range attrs {
if a.Attr.Type == syscall.IFA_LOCAL {
ipPointToPoint = true
break
}
}
}
for _, a := range attrs {
if ipPointToPoint && a.Attr.Type == syscall.IFA_ADDRESS || !ipPointToPoint && a.Attr.Type == syscall.IFA_LOCAL {
continue
}
switch ifam.Family {
case syscall.AF_INET:
return &IPNet{IP: IPv4(a.Value[0], a.Value[1], a.Value[2], a.Value[3]), Mask: CIDRMask(int(ifam.Prefixlen), 8*IPv4len)}
case syscall.AF_INET6:
ifa := &IPNet{IP: make(IP, IPv6len), Mask: CIDRMask(int(ifam.Prefixlen), 8*IPv6len)}
copy(ifa.IP, a.Value[:])
return ifa
}
}
return nil
}
// interfaceMulticastAddrTable returns addresses for a specific
// interface.
func interfaceMulticastAddrTable(ifi *Interface) ([]Addr, error) {
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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