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moby--moby/libnetwork/default_gateway.go

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package libnetwork
import (
"fmt"
"github.com/docker/libnetwork/types"
)
const (
libnGWNetwork = "docker_gwbridge"
gwEPlen = 12
)
var procGwNetwork = make(chan (bool), 1)
/*
libnetwork creates a bridge network "docker_gw_bridge" for providing
default gateway for the containers if none of the container's endpoints
have GW set by the driver. ICC is set to false for the GW_bridge network.
If a driver can't provide external connectivity it can choose to not set
the GW IP for the endpoint.
endpoint on the GW_bridge network is managed dynamically by libnetwork.
ie:
- its created when an endpoint without GW joins the container
- its deleted when an endpoint with GW joins the container
*/
func (sb *sandbox) setupDefaultGW() error {
// check if the container already has a GW endpoint
if ep := sb.getEndpointInGWNetwork(); ep != nil {
return nil
}
c := sb.controller
// Look for default gw network. In case of error (includes not found),
// retry and create it if needed in a serialized execution.
n, err := c.NetworkByName(libnGWNetwork)
if err != nil {
if n, err = c.defaultGwNetwork(); err != nil {
return err
}
}
createOptions := []EndpointOption{CreateOptionAnonymous()}
eplen := gwEPlen
if len(sb.containerID) < gwEPlen {
eplen = len(sb.containerID)
}
newEp, err := n.CreateEndpoint("gateway_"+sb.containerID[0:eplen], createOptions...)
if err != nil {
return fmt.Errorf("container %s: endpoint create on GW Network failed: %v", sb.containerID, err)
}
epLocal := newEp.(*endpoint)
if err := epLocal.sbJoin(sb); err != nil {
return fmt.Errorf("container %s: endpoint join on GW Network failed: %v", sb.containerID, err)
}
return nil
}
// If present, detach and remove the endpoint connecting the sandbox to the default gw network.
func (sb *sandbox) clearDefaultGW() error {
var ep *endpoint
if ep = sb.getEndpointInGWNetwork(); ep == nil {
return nil
}
if err := ep.sbLeave(sb, false); err != nil {
return fmt.Errorf("container %s: endpoint leaving GW Network failed: %v", sb.containerID, err)
}
if err := ep.Delete(false); err != nil {
return fmt.Errorf("container %s: deleting endpoint on GW Network failed: %v", sb.containerID, err)
}
return nil
}
// Evaluate whether the sandbox requires a default gateway based
// on the endpoints to which it is connected. It does not account
// for the default gateway network endpoint.
func (sb *sandbox) needDefaultGW() bool {
var needGW bool
for _, ep := range sb.getConnectedEndpoints() {
if ep.endpointInGWNetwork() {
continue
}
if ep.getNetwork().Type() == "null" || ep.getNetwork().Type() == "host" {
continue
}
if ep.getNetwork().Internal() {
continue
}
// During stale sandbox cleanup, joinInfo may be nil
if ep.joinInfo != nil && ep.joinInfo.disableGatewayService {
continue
}
// TODO v6 needs to be handled.
if len(ep.Gateway()) > 0 {
return false
}
for _, r := range ep.StaticRoutes() {
if r.Destination.String() == "0.0.0.0/0" {
return false
}
}
needGW = true
}
return needGW
}
func (sb *sandbox) getEndpointInGWNetwork() *endpoint {
for _, ep := range sb.getConnectedEndpoints() {
if ep.getNetwork().name == libnGWNetwork {
return ep
}
}
return nil
}
func (ep *endpoint) endpointInGWNetwork() bool {
if ep.getNetwork().name == libnGWNetwork {
return true
}
return false
}
func (sb *sandbox) getEPwithoutGateway() *endpoint {
for _, ep := range sb.getConnectedEndpoints() {
if ep.getNetwork().Type() == "null" || ep.getNetwork().Type() == "host" {
continue
}
if len(ep.Gateway()) == 0 {
return ep
}
}
return nil
}
// Looks for the default gw network and creates it if not there.
// Parallel executions are serialized.
func (c *controller) defaultGwNetwork() (Network, error) {
procGwNetwork <- true
defer func() { <-procGwNetwork }()
n, err := c.NetworkByName(libnGWNetwork)
if err != nil {
if _, ok := err.(types.NotFoundError); ok {
n, err = c.createGWNetwork()
}
}
return n, err
}
// Returns the endpoint which is providing external connectivity to the sandbox
func (sb *sandbox) getGatewayEndpoint() *endpoint {
for _, ep := range sb.getConnectedEndpoints() {
if ep.getNetwork().Type() == "null" || ep.getNetwork().Type() == "host" {
continue
}
if len(ep.Gateway()) != 0 {
return ep
}
}
return nil
}