mirror of
https://github.com/tim-beatham/smegmesh.git
synced 2025-08-14 07:18:32 +02:00
Removed interface manipulation via os.Exec into
rtnetlink calls
This commit is contained in:
Tim Beatham
300
pkg/lib/rtnetlink.go
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300
pkg/lib/rtnetlink.go
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@ -0,0 +1,300 @@
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package lib
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import (
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"encoding/binary"
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"fmt"
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"net"
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"github.com/jsimonetti/rtnetlink"
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logging "github.com/tim-beatham/wgmesh/pkg/log"
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"golang.org/x/sys/unix"
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)
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type RtNetlinkConfig struct {
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conn *rtnetlink.Conn
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}
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func NewRtNetlinkConfig() (*RtNetlinkConfig, error) {
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conn, err := rtnetlink.Dial(nil)
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if err != nil {
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return nil, err
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}
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return &RtNetlinkConfig{conn: conn}, nil
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}
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const WIREGUARD_MTU = 1420
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// Create a netlink interface if it does not exist. ifName is the name of the netlink interface
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func (c *RtNetlinkConfig) CreateLink(ifName string) error {
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_, err := net.InterfaceByName(ifName)
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if err == nil {
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return fmt.Errorf("interface %s already exists", ifName)
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}
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err = c.conn.Link.New(&rtnetlink.LinkMessage{
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Family: unix.AF_UNSPEC,
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Flags: unix.IFF_UP,
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Attributes: &rtnetlink.LinkAttributes{
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Name: ifName,
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Info: &rtnetlink.LinkInfo{Kind: "wireguard"},
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MTU: uint32(WIREGUARD_MTU),
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},
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})
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if err != nil {
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return fmt.Errorf("failed to create wireguard interface: %w", err)
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}
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return nil
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}
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// Delete link delete the specified interface
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func (c *RtNetlinkConfig) DeleteLink(ifName string) error {
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iface, err := net.InterfaceByName(ifName)
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if err != nil {
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return fmt.Errorf("failed to get interface %s %w", ifName, err)
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}
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err = c.conn.Link.Delete(uint32(iface.Index))
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if err != nil {
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return fmt.Errorf("failed to delete wg interface %w", err)
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}
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return nil
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}
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// AddAddress adds an address to the given interface.
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func (c *RtNetlinkConfig) AddAddress(ifName string, address string) error {
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iface, err := net.InterfaceByName(ifName)
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if err != nil {
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return fmt.Errorf("failed to get interface %s error: %w", ifName, err)
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}
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addr, cidr, err := net.ParseCIDR(address)
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if err != nil {
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return fmt.Errorf("failed to parse CIDR %s error: %w", addr, err)
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}
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family := unix.AF_INET6
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ipv4 := cidr.IP.To4()
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if ipv4 != nil {
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family = unix.AF_INET
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}
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// Calculate the prefix length
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ones, _ := cidr.Mask.Size()
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// Calculate the broadcast IP
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// Only used when family is AF_INET
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var brd net.IP
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if ipv4 != nil {
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brd = make(net.IP, len(ipv4))
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binary.BigEndian.PutUint32(brd, binary.BigEndian.Uint32(ipv4)|^binary.BigEndian.Uint32(net.IP(cidr.Mask).To4()))
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}
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err = c.conn.Address.New(&rtnetlink.AddressMessage{
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Family: uint8(family),
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PrefixLength: uint8(ones),
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Scope: unix.RT_SCOPE_UNIVERSE,
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Index: uint32(iface.Index),
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Attributes: &rtnetlink.AddressAttributes{
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Address: addr,
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Local: addr,
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Broadcast: brd,
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},
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})
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if err != nil {
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err = fmt.Errorf("failed to add address to link %w", err)
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}
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return err
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}
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// AddRoute: adds a route to the routing table.
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// ifName is the intrface to add the route to
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// gateway is the IP of the gateway device to hop to
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// dst is the network prefix of the advertised destination
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func (c *RtNetlinkConfig) AddRoute(ifName string, route Route) error {
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iface, err := net.InterfaceByName(ifName)
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if err != nil {
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return fmt.Errorf("failed accessing interface %s error %w", ifName, err)
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}
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gw := route.Gateway
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dst := route.Destination
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var family uint8 = unix.AF_INET6
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if dst.IP.To4() != nil {
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family = unix.AF_INET
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}
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attr := rtnetlink.RouteAttributes{
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Dst: dst.IP,
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OutIface: uint32(iface.Index),
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Gateway: gw,
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}
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ones, _ := dst.Mask.Size()
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err = c.conn.Route.Replace(&rtnetlink.RouteMessage{
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Family: family,
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Table: unix.RT_TABLE_MAIN,
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Protocol: unix.RTPROT_BOOT,
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Scope: unix.RT_SCOPE_LINK,
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Type: unix.RTN_UNICAST,
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DstLength: uint8(ones),
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Attributes: attr,
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})
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if err != nil {
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return fmt.Errorf("failed to add route %w", err)
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}
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return nil
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}
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// DeleteRoute deletes routes with the gateway and destination
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func (c *RtNetlinkConfig) DeleteRoute(ifName string, route Route) error {
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iface, err := net.InterfaceByName(ifName)
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if err != nil {
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return fmt.Errorf("failed accessing interface %s error %w", ifName, err)
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}
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gw := route.Gateway
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dst := route.Destination
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var family uint8 = unix.AF_INET6
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if dst.IP.To4() != nil {
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family = unix.AF_INET
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}
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attr := rtnetlink.RouteAttributes{
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Dst: dst.IP,
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OutIface: uint32(iface.Index),
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Gateway: gw,
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}
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ones, _ := dst.Mask.Size()
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err = c.conn.Route.Delete(&rtnetlink.RouteMessage{
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Family: family,
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Table: unix.RT_TABLE_MAIN,
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Protocol: unix.RTPROT_BOOT,
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Scope: unix.RT_SCOPE_LINK,
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Type: unix.RTN_UNICAST,
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DstLength: uint8(ones),
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Attributes: attr,
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})
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if err != nil {
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return fmt.Errorf("failed to delete route %w", err)
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}
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return nil
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}
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type Route struct {
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Gateway net.IP
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Destination net.IPNet
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}
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func (r1 Route) equal(r2 Route) bool {
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return r1.Gateway.String() == r2.Gateway.String() &&
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r1.Destination.String() == r2.Destination.String()
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}
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// DeleteRoutes deletes all routes not in exclude
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func (c *RtNetlinkConfig) DeleteRoutes(ifName string, family uint8, exclude ...Route) error {
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routes := make([]rtnetlink.RouteMessage, 0)
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if len(exclude) != 0 {
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lRoutes, err := c.listRoutes(ifName, family, exclude[0].Gateway)
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if err != nil {
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return err
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}
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routes = lRoutes
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}
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ifRoutes := make([]Route, 0)
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for _, rtRoute := range routes {
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logging.Log.WriteInfof("Routes: %s", rtRoute.Attributes.Dst.String())
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maskSize := 128
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if family == unix.AF_INET {
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maskSize = 32
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}
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cidr := net.CIDRMask(int(rtRoute.DstLength), maskSize)
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route := Route{
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Gateway: rtRoute.Attributes.Gateway,
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Destination: net.IPNet{IP: rtRoute.Attributes.Dst, Mask: cidr},
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}
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ifRoutes = append(ifRoutes, route)
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}
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shouldExclude := func(r Route) bool {
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for _, route := range exclude {
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if route.equal(r) {
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return false
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}
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}
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return true
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}
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toDelete := Filter(ifRoutes, shouldExclude)
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for _, route := range toDelete {
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logging.Log.WriteInfof("Deleting route %s", route.Destination.String())
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err := c.DeleteRoute(ifName, route)
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if err != nil {
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return err
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}
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}
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return nil
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}
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// listRoutes lists all routes on the interface
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func (c *RtNetlinkConfig) listRoutes(ifName string, family uint8, gateway net.IP) ([]rtnetlink.RouteMessage, error) {
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iface, err := net.InterfaceByName(ifName)
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if err != nil {
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return nil, fmt.Errorf("failed accessing interface %s error %w", ifName, err)
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}
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routes, err := c.conn.Route.List()
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if err != nil {
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return nil, fmt.Errorf("failed to get route %w", err)
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}
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filterFunc := func(r rtnetlink.RouteMessage) bool {
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return r.Attributes.Gateway.Equal(gateway) && r.Attributes.OutIface == uint32(iface.Index)
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}
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routes = Filter(routes, filterFunc)
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return routes, nil
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}
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func (c *RtNetlinkConfig) Close() error {
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return c.conn.Close()
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}
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