dotcloud/docker

package libnetwork

import (
    "context"
    "fmt"
    "strings"

    "github.com/containerd/log"
    "github.com/docker/docker/libnetwork/netlabel"
    "github.com/docker/docker/libnetwork/types"
)

const (
    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{}

    var gwName string
    if len(sb.containerID) <= gwEPlen {
        gwName = "gateway_" + sb.containerID
    } else {
        gwName = "gateway_" + sb.id[:gwEPlen]
    }

    sbLabels := sb.Labels()

    if sbLabels[netlabel.PortMap] != nil {
        createOptions = append(createOptions, CreateOptionPortMapping(sbLabels[netlabel.PortMap].([]types.PortBinding)))
    }

    if sbLabels[netlabel.ExposedPorts] != nil {
        createOptions = append(createOptions, CreateOptionExposedPorts(sbLabels[netlabel.ExposedPorts].([]types.TransportPort)))
    }

    epOption := getPlatformOption()
    if epOption != nil {
        createOptions = append(createOptions, epOption)
    }

    newEp, err := n.CreateEndpoint(context.TODO(), gwName, createOptions...)
    if err != nil {
        return fmt.Errorf("container %s: endpoint create on GW Network failed: %v", sb.containerID, err)
    }

    defer func() {
        if err != nil {
            if err2 := newEp.Delete(context.WithoutCancel(context.TODO()), true); err2 != nil {
                log.G(context.TODO()).Warnf("Failed to remove gw endpoint for container %s after failing to join the gateway network: %v",
                    sb.containerID, err2)
            }
        }
    }()

    if err = newEp.sbJoin(context.TODO(), 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(context.TODO(), sb, false); err != nil {
        return fmt.Errorf("container %s: endpoint leaving GW Network failed: %v", sb.containerID, err)
    }
    if err := ep.Delete(context.TODO(), 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.Endpoints() {
        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 != nil && r.Destination.String() == "0.0.0.0/0" {
                return false
            }
        }
        needGW = true
    }

    return needGW
}

func (sb *Sandbox) getEndpointInGWNetwork() *Endpoint {
    for _, ep := range sb.Endpoints() {
        if ep.getNetwork().name == libnGWNetwork && strings.HasPrefix(ep.Name(), "gateway_") {
            return ep
        }
    }
    return nil
}

func (ep *Endpoint) endpointInGWNetwork() bool {
    if ep.getNetwork().name == libnGWNetwork && strings.HasPrefix(ep.Name(), "gateway_") {
        return true
    }
    return false
}

// 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 _, 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.Endpoints() {
        if ep.getNetwork().Type() == "null" || ep.getNetwork().Type() == "host" {
            continue
        }
        if len(ep.Gateway()) != 0 {
            return ep
        }
    }
    return nil
}