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netlink.go
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netlink.go
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// SPDX-FileCopyrightText: 2022 SAP SE or an SAP affiliate company and IronCore contributors
// SPDX-License-Identifier: Apache-2.0
package metalbond
import (
"fmt"
"net"
"sync"
log "github.com/sirupsen/logrus"
"github.com/vishvananda/netlink"
)
const METALBOND_RT_PROTO netlink.RouteProtocol = 254
type NetlinkClient struct {
config NetlinkClientConfig
tunDevice netlink.Link
mtx sync.Mutex
}
type NetlinkClientConfig struct {
VNITableMap map[VNI]int
LinkName string
IPv4Only bool
}
func NewNetlinkClient(config NetlinkClientConfig) (*NetlinkClient, error) {
link, err := netlink.LinkByName(config.LinkName)
if err != nil {
return nil, fmt.Errorf("Cannot find tun device '%s': %v", config.LinkName, err)
}
// TODO: Remove all routes from route tables defined in config.VNITableMap with Protocol = METALBOND_RT_PROTO
// to clean up old, stale routes installed by a prior metalbond client instance
return &NetlinkClient{
config: config,
tunDevice: link,
}, nil
}
func (c *NetlinkClient) AddRoute(vni VNI, dest Destination, hop NextHop) error {
c.mtx.Lock()
defer c.mtx.Unlock()
if c.config.IPv4Only && dest.IPVersion != IPV4 {
log.Infof("Received non-IPv4 route will not be installed in kernel route table (IPv4-only mode)")
return nil
}
table, exists := c.config.VNITableMap[vni]
if !exists {
return fmt.Errorf("No route table ID known for given VNI")
}
_, dst, err := net.ParseCIDR(dest.Prefix.String())
if err != nil {
return fmt.Errorf("cannot parse destination prefix: %v", err)
}
encap := netlink.IP6tnlEncap{
Dst: net.ParseIP(hop.TargetAddress.String()),
Src: net.ParseIP("::"), // what source ip to put here? Metalbond object, m, does not contain this info yet.
}
route := &netlink.Route{
LinkIndex: c.tunDevice.Attrs().Index,
Dst: dst,
Encap: &encap,
Table: table,
Protocol: METALBOND_RT_PROTO,
} // by default, the route is already installed into the kernel table without explicite specification
if err := netlink.RouteAdd(route); err != nil {
return fmt.Errorf("cannot add route to %s (table %d) to kernel: %v", dest, table, err)
}
return nil
}
func (c *NetlinkClient) RemoveRoute(vni VNI, dest Destination, hop NextHop) error {
c.mtx.Lock()
defer c.mtx.Unlock()
if c.config.IPv4Only && dest.IPVersion != IPV4 {
return nil
}
table, exists := c.config.VNITableMap[vni]
if !exists {
return fmt.Errorf("No route table ID known for given VNI")
}
_, dst, err := net.ParseCIDR(dest.Prefix.String())
if err != nil {
return fmt.Errorf("cannot parse destination prefix: %v", err)
}
encap := netlink.IP6tnlEncap{
Dst: net.ParseIP(hop.TargetAddress.String()),
Src: net.ParseIP("::"), // what source ip to put here? Metalbond object, m, does not contain this info yet.
}
route := &netlink.Route{
LinkIndex: c.tunDevice.Attrs().Index,
Dst: dst,
Encap: &encap,
Table: table,
Protocol: METALBOND_RT_PROTO,
} // by default, the route is already installed into the kernel table without explicite specification
if err := netlink.RouteDel(route); err != nil {
return fmt.Errorf("cannot remove route to %s (table %d) from kernel: %v", dest, table, err)
}
return nil
}