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//go:build linux
// +build linux
package bridge
import (
"fmt"
"os"
"path/filepath"
"github.com/docker/docker/libnetwork/netutils"
"github.com/sirupsen/logrus"
"github.com/vishvananda/netlink"
)
// SetupDevice create a new bridge interface/
func setupDevice(config *networkConfiguration, i *bridgeInterface) error {
// We only attempt to create the bridge when the requested device name is
// the default one. The default bridge name can be overridden with the
// DOCKER_TEST_CREATE_DEFAULT_BRIDGE env var. It should be used only for
// test purpose.
var defaultBridgeName string
if defaultBridgeName = os.Getenv("DOCKER_TEST_CREATE_DEFAULT_BRIDGE"); defaultBridgeName == "" {
defaultBridgeName = DefaultBridgeName
}
if config.BridgeName != defaultBridgeName && config.DefaultBridge {
return NonDefaultBridgeExistError(config.BridgeName)
}
// Set the bridgeInterface netlink.Bridge.
i.Link = &netlink.Bridge{
LinkAttrs: netlink.LinkAttrs{
Name: config.BridgeName,
},
}
// Set the bridge's MAC address. Requires kernel version 3.3 or up.
hwAddr := netutils.GenerateRandomMAC()
i.Link.Attrs().HardwareAddr = hwAddr
logrus.Debugf("Setting bridge mac address to %s", hwAddr)
if err := i.nlh.LinkAdd(i.Link); err != nil {
logrus.WithError(err).Errorf("Failed to create bridge %s via netlink", config.BridgeName)
return err
}
return nil
}
func setupDefaultSysctl(config *networkConfiguration, i *bridgeInterface) error {
// Disable IPv6 router advertisements originating on the bridge
sysPath := filepath.Join("/proc/sys/net/ipv6/conf/", config.BridgeName, "accept_ra")
if _, err := os.Stat(sysPath); err != nil {
logrus.
WithField("bridge", config.BridgeName).
WithField("syspath", sysPath).
Info("failed to read ipv6 net.ipv6.conf.<bridge>.accept_ra")
return nil
}
if err := os.WriteFile(sysPath, []byte{'0', '\n'}, 0644); err != nil {
logrus.WithError(err).Warn("unable to disable IPv6 router advertisement")
}
return nil
}
// SetupDeviceUp ups the given bridge interface.
func setupDeviceUp(config *networkConfiguration, i *bridgeInterface) error {
err := i.nlh.LinkSetUp(i.Link)
if err != nil {
return fmt.Errorf("Failed to set link up for %s: %v", config.BridgeName, err)
}
// Attempt to update the bridge interface to refresh the flags status,
// ignoring any failure to do so.
if lnk, err := i.nlh.LinkByName(config.BridgeName); err == nil {
i.Link = lnk
} else {
logrus.Warnf("Failed to retrieve link for interface (%s): %v", config.BridgeName, err)
}
return nil
}
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