Implement RTM_NEWROUTE in netstack to create/replace a route.

PiperOrigin-RevId: 650814137
2026-05-22 17:12:49 -07:00 · 2024-07-09 18:04:19 -07:00
parent 16ebae768c
commit 35309c96c0
13 changed files with 403 additions and 1 deletions
@@ -742,6 +742,122 @@ func (s *Stack) RouteTable() []inet.Route {
 	return routeTable
 }

+// NewRoute implements inet.Stack.NewRoute.
+func (s *Stack) NewRoute(ctx context.Context, msg *nlmsg.Message) *syserr.Error {
+	var routeMsg linux.RouteMessage
+	attrs, ok := msg.GetData(&routeMsg)
+	if !ok {
+		return syserr.ErrInvalidArgument
+	}
+
+	route := inet.Route{
+		Family:   routeMsg.Family,
+		DstLen:   routeMsg.DstLen,
+		SrcLen:   routeMsg.SrcLen,
+		TOS:      routeMsg.TOS,
+		Table:    routeMsg.Table,
+		Protocol: routeMsg.Protocol,
+		Scope:    routeMsg.Scope,
+		Type:     routeMsg.Type,
+		Flags:    routeMsg.Flags,
+	}
+
+	for !attrs.Empty() {
+		ahdr, value, rest, ok := attrs.ParseFirst()
+		if !ok {
+			return syserr.ErrInvalidArgument
+		}
+		attrs = rest
+
+		switch ahdr.Type {
+		case linux.RTA_DST:
+			if len(value) < 1 {
+				return syserr.ErrInvalidArgument
+			}
+			route.DstAddr = value
+		case linux.RTA_SRC:
+			if len(value) < 1 {
+				return syserr.ErrInvalidArgument
+			}
+			route.SrcAddr = value
+		case linux.RTA_OIF:
+			oif := nlmsg.BytesView(value)
+			outputInterface, ok := oif.Int32()
+			if !ok {
+				return syserr.ErrInvalidArgument
+			}
+			if _, exist := s.Interfaces()[outputInterface]; !exist {
+				return syserr.ErrNoDevice
+			}
+			route.OutputInterface = outputInterface
+		case linux.RTA_GATEWAY:
+			if len(value) < 1 {
+				return syserr.ErrInvalidArgument
+			}
+			route.GatewayAddr = value
+		case linux.RTA_PRIORITY:
+		default:
+			ctx.Warningf("Unknown attribute: %v", ahdr.Type)
+			return syserr.ErrNotSupported
+		}
+	}
+
+	var dest tcpip.Subnet
+	// When no destination address is provided, the new route might be the default route.
+	if route.DstAddr == nil {
+		if route.GatewayAddr == nil {
+			return syserr.ErrInvalidArgument
+		}
+		switch len(route.GatewayAddr) {
+		case header.IPv4AddressSize:
+			subnet, err := tcpip.NewSubnet(tcpip.AddrFromSlice(tcpip.IPv4Zero), tcpip.MaskFromBytes(tcpip.IPv4Zero))
+			if err != nil {
+				return syserr.ErrInvalidArgument
+			}
+			dest = subnet
+		case header.IPv6AddressSize:
+			subnet, err := tcpip.NewSubnet(tcpip.AddrFromSlice(tcpip.IPv6Zero), tcpip.MaskFromBytes(tcpip.IPv6Zero))
+			if err != nil {
+				return syserr.ErrInvalidArgument
+			}
+			dest = subnet
+		default:
+			return syserr.ErrInvalidArgument
+		}
+	} else {
+		dest = tcpip.AddressWithPrefix{
+			Address:   tcpip.AddrFromSlice(route.DstAddr),
+			PrefixLen: int(route.DstLen)}.Subnet()
+	}
+
+	localRoute := tcpip.Route{
+		Destination: dest,
+		Gateway:     tcpip.AddrFromSlice(route.GatewayAddr),
+		NIC:         tcpip.NICID(route.OutputInterface),
+	}
+	if len(route.SrcAddr) != 0 {
+		localRoute.SourceHint = tcpip.AddrFromSlice(route.SrcAddr)
+	}
+	found := false
+	for _, rt := range s.Stack.GetRouteTable() {
+		if localRoute.Equal(rt) {
+			found = true
+			break
+		}
+	}
+	flags := msg.Header().Flags
+	switch {
+	case !found && flags&linux.NLM_F_CREATE == linux.NLM_F_CREATE:
+		s.Stack.AddRoute(localRoute)
+	case found && flags&linux.NLM_F_REPLACE != linux.NLM_F_REPLACE:
+		return syserr.ErrExists
+	}
+	if flags&linux.NLM_F_REPLACE == linux.NLM_F_REPLACE {
+		s.Stack.ReplaceRoute(localRoute)
+	}
+	return nil
+}
+
 // IPTables returns the stack's iptables.
 func (s *Stack) IPTables() (*stack.IPTables, error) {
 	return s.Stack.IPTables(), nil