status-go/vendor/github.com/libp2p/go-netroute/netroute_plan9.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
}