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link.go
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link.go
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// SPDX-License-Identifier: Apache-2.0
// Copyright Authors of Cilium
package link
import (
"context"
"fmt"
"strconv"
"sync"
"github.com/vishvananda/netlink"
"github.com/cilium/cilium/pkg/controller"
"github.com/cilium/cilium/pkg/lock"
"github.com/cilium/cilium/pkg/mac"
"github.com/cilium/cilium/pkg/time"
)
var (
// linkCache is the singleton instance of the LinkCache, only needed to
// ensure that the single controller used to update the LinkCache is
// triggered exactly once and the same instance is handed to all users.
linkCache LinkCache
once sync.Once
linkCacheControllerGroup = controller.NewGroup("link-cache")
)
// DeleteByName deletes the interface with the name ifName.
func DeleteByName(ifName string) error {
iface, err := netlink.LinkByName(ifName)
if err != nil {
return fmt.Errorf("failed to lookup %q: %v", ifName, err)
}
if err = netlink.LinkDel(iface); err != nil {
return fmt.Errorf("failed to delete %q: %v", ifName, err)
}
return nil
}
// Rename renames a network link
func Rename(curName, newName string) error {
link, err := netlink.LinkByName(curName)
if err != nil {
return err
}
return netlink.LinkSetName(link, newName)
}
func GetHardwareAddr(ifName string) (mac.MAC, error) {
iface, err := netlink.LinkByName(ifName)
if err != nil {
return nil, err
}
return mac.MAC(iface.Attrs().HardwareAddr), nil
}
func GetIfIndex(ifName string) (uint32, error) {
iface, err := netlink.LinkByName(ifName)
if err != nil {
return 0, err
}
return uint32(iface.Attrs().Index), nil
}
type LinkCache struct {
mu lock.RWMutex
indexToName map[int]string
}
// NewLinkCache begins monitoring local interfaces for changes in order to
// track local link information.
func NewLinkCache() *LinkCache {
once.Do(func() {
linkCache = LinkCache{}
controller.NewManager().UpdateController("link-cache",
controller.ControllerParams{
Group: linkCacheControllerGroup,
RunInterval: 15 * time.Second,
DoFunc: func(ctx context.Context) error {
return linkCache.syncCache()
},
},
)
})
return &linkCache
}
func (c *LinkCache) syncCache() error {
links, err := netlink.LinkList()
if err != nil {
return err
}
indexToName := make(map[int]string, len(links))
for _, link := range links {
indexToName[link.Attrs().Index] = link.Attrs().Name
}
c.mu.Lock()
c.indexToName = indexToName
c.mu.Unlock()
return nil
}
func (c *LinkCache) lookupName(ifIndex int) (string, bool) {
c.mu.RLock()
defer c.mu.RUnlock()
name, ok := c.indexToName[ifIndex]
return name, ok
}
// GetIfNameCached returns the name of an interface (if it exists) by looking
// it up in a regularly updated cache. The return result is the same as a map
// lookup, ie nil, false if there is no entry cached for this ifindex.
func (c *LinkCache) GetIfNameCached(ifIndex int) (string, bool) {
return c.lookupName(ifIndex)
}
// Name returns the name of a link by looking up the 'LinkCache', or returns a
// string containing the ifindex on cache miss.
func (c *LinkCache) Name(ifIndex uint32) string {
if name, ok := c.lookupName(int(ifIndex)); ok {
return name
}
return strconv.Itoa(int(ifIndex))
}