// 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("netlinkrib", err) } msgs, err := syscall.ParseNetlinkMessage(tab) if err != nil { return nil, os.NewSyscallError("parsenetlinkmessage", 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("parsenetlinkrouteattr", 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_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 := syscall.NetlinkRIB(syscall.RTM_GETADDR, syscall.AF_UNSPEC) if err != nil { return nil, os.NewSyscallError("netlinkrib", err) } msgs, err := syscall.ParseNetlinkMessage(tab) if err != nil { return nil, os.NewSyscallError("parsenetlinkmessage", 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("parsenetlinkrouteattr", err) } ifa := newAddr(ifam, attrs) if ifa != nil { ifat = append(ifat, ifa) } } } } return ifat, nil } func newAddr(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. 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 { 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) } } } 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) } } return ifmat }