142 lines
3.3 KiB
Go
142 lines
3.3 KiB
Go
// Generate a local routing table structure following the code at
|
|
// https://github.com/google/gopacket/blob/master/routing/routing.go
|
|
//
|
|
// Plan 9 networking is described here: http://9p.io/magic/man2html/3/ip
|
|
|
|
package netroute
|
|
|
|
import (
|
|
"bytes"
|
|
"fmt"
|
|
"io/ioutil"
|
|
"net"
|
|
"strconv"
|
|
"strings"
|
|
|
|
"github.com/google/gopacket/routing"
|
|
)
|
|
|
|
const netdir = "/net"
|
|
|
|
func New() (routing.Router, error) {
|
|
rtr := &router{}
|
|
rtr.ifaces = make(map[int]net.Interface)
|
|
rtr.addrs = make(map[int]ipAddrs)
|
|
ifaces, err := net.Interfaces()
|
|
if err != nil {
|
|
return nil, fmt.Errorf("could not get interfaces: %v", err)
|
|
}
|
|
for _, iface := range ifaces {
|
|
rtr.ifaces[iface.Index] = iface
|
|
var addrs ipAddrs
|
|
ifaceAddrs, err := iface.Addrs()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
for _, addr := range ifaceAddrs {
|
|
if inet, ok := addr.(*net.IPNet); ok {
|
|
// Go has a nasty habit of giving you IPv4s as ::ffff:1.2.3.4 instead of 1.2.3.4.
|
|
// We want to use mapped v4 addresses as v4 preferred addresses, never as v6
|
|
// preferred addresses.
|
|
if v4 := inet.IP.To4(); v4 != nil {
|
|
if addrs.v4 == nil {
|
|
addrs.v4 = v4
|
|
}
|
|
} else if addrs.v6 == nil {
|
|
addrs.v6 = inet.IP
|
|
}
|
|
}
|
|
}
|
|
rtr.addrs[iface.Index] = addrs
|
|
}
|
|
|
|
rtr.v4, rtr.v6, err = parseIPRoutes()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return rtr, nil
|
|
}
|
|
|
|
func parseIPRoutes() (v4, v6 routeSlice, err error) {
|
|
buf, err := ioutil.ReadFile(netdir + "/iproute")
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
for {
|
|
i := bytes.IndexRune(buf, '\n')
|
|
if i <= 0 {
|
|
break
|
|
}
|
|
f := strings.Fields(string(buf[:i]))
|
|
buf = buf[i+1:]
|
|
|
|
if len(f) < 8 {
|
|
return nil, nil, fmt.Errorf("iproute entry contains %d fields", len(f))
|
|
}
|
|
flags, rt, err := parseRoute(f)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
if rt.Dst != nil {
|
|
// If gateway for destination 127.0.0.1/32 is 127.0.0.1, set it to nil.
|
|
if m, n := rt.Dst.Mask.Size(); n > 0 && m == n && rt.Dst.IP.Equal(rt.Gateway) {
|
|
rt.Gateway = nil
|
|
}
|
|
}
|
|
if strings.ContainsRune(flags, '4') { // IPv4
|
|
v4 = append(v4, rt)
|
|
}
|
|
if strings.ContainsRune(flags, '6') { // IPv6
|
|
v6 = append(v6, rt)
|
|
}
|
|
}
|
|
return v4, v6, nil
|
|
}
|
|
|
|
func parseRoute(f []string) (flags string, rt *rtInfo, err error) {
|
|
rt = new(rtInfo)
|
|
isV4 := strings.ContainsRune(f[3], '4') // flags
|
|
|
|
rt.PrefSrc, rt.Src, err = parsePlan9CIDR(f[6], f[7], isV4)
|
|
if err != nil {
|
|
return "", nil, err
|
|
}
|
|
_, rt.Dst, err = parsePlan9CIDR(f[0], f[1], isV4)
|
|
if err != nil {
|
|
return "", nil, err
|
|
}
|
|
rt.Gateway = net.ParseIP(f[2])
|
|
|
|
n, err := strconv.ParseUint(f[5], 10, 32)
|
|
if err != nil {
|
|
return "", nil, err
|
|
}
|
|
rt.InputIface = 0
|
|
rt.OutputIface = uint32(n) + 1 // starts at 0, so net package adds 1
|
|
rt.Priority = 0
|
|
return f[3], rt, nil
|
|
}
|
|
|
|
func parsePlan9CIDR(addr, mask string, isV4 bool) (net.IP, *net.IPNet, error) {
|
|
if len(mask) == 0 || mask[0] != '/' {
|
|
return nil, nil, fmt.Errorf("invalid CIDR mask %v", mask)
|
|
}
|
|
n, err := strconv.ParseUint(mask[1:], 10, 32)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
ip := net.ParseIP(addr)
|
|
iplen := net.IPv6len
|
|
if isV4 {
|
|
// Plan 9 uses IPv6 mask for IPv4 addresses
|
|
n -= 8 * (net.IPv6len - net.IPv4len)
|
|
iplen = net.IPv4len
|
|
}
|
|
if n == 0 && ip.IsUnspecified() {
|
|
return nil, nil, nil
|
|
}
|
|
m := net.CIDRMask(int(n), 8*iplen)
|
|
return ip, &net.IPNet{IP: ip.Mask(m), Mask: m}, nil
|
|
}
|