func ruleHandle(rule *Rule, req *nl.NetlinkRequest) error {
msg := nl.NewRtMsg()
msg.Family = syscall.AF_INET
var dstFamily uint8
var rtAttrs []*nl.RtAttr
if rule.Dst != nil && rule.Dst.IP != nil {
dstLen, _ := rule.Dst.Mask.Size()
msg.Dst_len = uint8(dstLen)
msg.Family = uint8(nl.GetIPFamily(rule.Dst.IP))
dstFamily = msg.Family
var dstData []byte
if msg.Family == syscall.AF_INET {
dstData = rule.Dst.IP.To4()
} else {
dstData = rule.Dst.IP.To16()
}
rtAttrs = append(rtAttrs, nl.NewRtAttr(syscall.RTA_DST, dstData))
}
if rule.Src != nil && rule.Src.IP != nil {
msg.Family = uint8(nl.GetIPFamily(rule.Src.IP))
if dstFamily != 0 && dstFamily != msg.Family {
return fmt.Errorf("source and destination ip are not the same IP family")
}
srcLen, _ := rule.Src.Mask.Size()
msg.Src_len = uint8(srcLen)
var srcData []byte
if msg.Family == syscall.AF_INET {
srcData = rule.Src.IP.To4()
} else {
srcData = rule.Src.IP.To16()
}
rtAttrs = append(rtAttrs, nl.NewRtAttr(syscall.RTA_SRC, srcData))
}
if rule.Table >= 0 {
msg.Table = uint8(rule.Table)
if rule.Table >= 256 {
msg.Table = syscall.RT_TABLE_UNSPEC
}
}
req.AddData(msg)
for i := range rtAttrs {
req.AddData(rtAttrs[i])
}
var (
b = make([]byte, 4)
native = nl.NativeEndian()
)
if rule.Priority >= 0 {
native.PutUint32(b, uint32(rule.Priority))
req.AddData(nl.NewRtAttr(nl.FRA_PRIORITY, b))
}
if rule.Mark >= 0 {
native.PutUint32(b, uint32(rule.Mark))
req.AddData(nl.NewRtAttr(nl.FRA_FWMARK, b))
}
if rule.Mask >= 0 {
native.PutUint32(b, uint32(rule.Mask))
req.AddData(nl.NewRtAttr(nl.FRA_FWMASK, b))
}
if rule.Flow >= 0 {
native.PutUint32(b, uint32(rule.Flow))
req.AddData(nl.NewRtAttr(nl.FRA_FLOW, b))
}
if rule.TunID > 0 {
native.PutUint32(b, uint32(rule.TunID))
req.AddData(nl.NewRtAttr(nl.FRA_TUN_ID, b))
}
if rule.Table >= 256 {
native.PutUint32(b, uint32(rule.Table))
req.AddData(nl.NewRtAttr(nl.FRA_TABLE, b))
}
if msg.Table > 0 {
if rule.SuppressPrefixlen >= 0 {
native.PutUint32(b, uint32(rule.SuppressPrefixlen))
req.AddData(nl.NewRtAttr(nl.FRA_SUPPRESS_PREFIXLEN, b))
}
if rule.SuppressIfgroup >= 0 {
native.PutUint32(b, uint32(rule.SuppressIfgroup))
req.AddData(nl.NewRtAttr(nl.FRA_SUPPRESS_IFGROUP, b))
}
}
if rule.IifName != "" {
req.AddData(nl.NewRtAttr(nl.FRA_IIFNAME, []byte(rule.IifName)))
}
if rule.OifName != "" {
req.AddData(nl.NewRtAttr(nl.FRA_OIFNAME, []byte(rule.OifName)))
}
if rule.Goto >= 0 {
msg.Type = nl.FR_ACT_NOP
native.PutUint32(b, uint32(rule.Goto))
req.AddData(nl.NewRtAttr(nl.FRA_GOTO, 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())
}