func routeHandle(route *Route, req *nl.NetlinkRequest) error {
if (route.Dst == nil || route.Dst.IP == nil) && route.Src == nil && route.Gw == nil {
return fmt.Errorf("one of Dst.IP, Src, or Gw must not be nil")
}
msg := nl.NewRtMsg()
msg.Scope = uint8(route.Scope)
family := -1
var rtAttrs []*nl.RtAttr
if route.Dst != nil && route.Dst.IP != nil {
dstLen, _ := route.Dst.Mask.Size()
msg.Dst_len = uint8(dstLen)
dstFamily := nl.GetIPFamily(route.Dst.IP)
family = dstFamily
var dstData []byte
if dstFamily == FAMILY_V4 {
dstData = route.Dst.IP.To4()
} else {
dstData = route.Dst.IP.To16()
}
rtAttrs = append(rtAttrs, nl.NewRtAttr(syscall.RTA_DST, dstData))
}
if route.Src != nil {
srcFamily := nl.GetIPFamily(route.Src)
if family != -1 && family != srcFamily {
return fmt.Errorf("source and destination ip are not the same IP family")
}
family = srcFamily
var srcData []byte
if srcFamily == FAMILY_V4 {
srcData = route.Src.To4()
} else {
srcData = route.Src.To16()
}
// The commonly used src ip for routes is actually PREFSRC
rtAttrs = append(rtAttrs, nl.NewRtAttr(syscall.RTA_PREFSRC, srcData))
}
if route.Gw != nil {
gwFamily := nl.GetIPFamily(route.Gw)
if family != -1 && family != gwFamily {
return fmt.Errorf("gateway, source, and destination ip are not the same IP family")
}
family = gwFamily
var gwData []byte
if gwFamily == FAMILY_V4 {
gwData = route.Gw.To4()
} else {
gwData = route.Gw.To16()
}
rtAttrs = append(rtAttrs, nl.NewRtAttr(syscall.RTA_GATEWAY, gwData))
}
msg.Family = uint8(family)
req.AddData(msg)
for _, attr := range rtAttrs {
req.AddData(attr)
}
var (
b = make([]byte, 4)
native = nl.NativeEndian()
)
native.PutUint32(b, uint32(route.LinkIndex))
req.AddData(nl.NewRtAttr(syscall.RTA_OIF, b))
_, err := req.Execute(syscall.NETLINK_ROUTE, 0)
return err
}
// RouteAdd will add a route to the system.
// Equivalent to: `ip route add $route`
func RouteAdd(route *Route) error {
req := nl.NewNetlinkRequest(syscall.RTM_NEWROUTE, syscall.NLM_F_CREATE|syscall.NLM_F_EXCL|syscall.NLM_F_ACK)
return routeHandle(route, req, nl.NewRtMsg())
}