dotcloud/docker

//go:build linux

package bridge

import (
    "context"
    "fmt"
    "net"

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

type link struct {
    parentIP net.IP
    childIP  net.IP
    ports    []types.TransportPort
    bridge   string
}

func (l *link) String() string {
    return fmt.Sprintf("%s <-> %s [%v] on %s", l.parentIP, l.childIP, l.ports, l.bridge)
}

func newLink(parentIP, childIP net.IP, ports []types.TransportPort, bridge string) (*link, error) {
    if parentIP == nil {
        return nil, fmt.Errorf("cannot link to a container with an empty parent IP address")
    }
    if childIP == nil {
        return nil, fmt.Errorf("cannot link to a container with an empty child IP address")
    }

    return &link{
        childIP:  childIP,
        parentIP: parentIP,
        ports:    ports,
        bridge:   bridge,
    }, nil
}

func (l *link) Enable() error {
    linkFunction := func() error {
        return linkContainers(iptables.Append, l.parentIP, l.childIP, l.ports, l.bridge, false)
    }
    if err := linkFunction(); err != nil {
        return err
    }

    iptables.OnReloaded(func() { _ = linkFunction() })
    return nil
}

func (l *link) Disable() {
    if err := linkContainers(iptables.Delete, l.parentIP, l.childIP, l.ports, l.bridge, true); err != nil {
        // @TODO: Return error once we have the iptables package return typed errors.
        log.G(context.TODO()).WithError(err).Errorf("Error removing IPTables rules for link: %s", l.String())
    }
}

func linkContainers(action iptables.Action, parentIP, childIP net.IP, ports []types.TransportPort, bridge string, ignoreErrors bool) error {
    if parentIP == nil {
        return fmt.Errorf("cannot link to a container with an empty parent IP address")
    }
    if childIP == nil {
        return fmt.Errorf("cannot link to a container with an empty child IP address")
    }

    chain := iptables.ChainInfo{Name: DockerChain}
    for _, port := range ports {
        err := chain.Link(action, parentIP, childIP, int(port.Port), port.Proto.String(), bridge)
        if !ignoreErrors && err != nil {
            return err
        }
    }
    return nil
}