dotcloud/docker

package bridge

import (
    "fmt"
    "strings"

    "github.com/docker/docker/libnetwork/ns"
    "github.com/vishvananda/netlink"
)

// setupVerifyAndReconcileIPv4 checks what IPv4 addresses the given i interface has
// and ensures that they match the passed network config.
func setupVerifyAndReconcileIPv4(config *networkConfiguration, i *bridgeInterface) error {
    // Fetch a slice of IPv4 addresses and a slice of IPv6 addresses from the bridge.
    addrsv4, err := i.addresses(netlink.FAMILY_V4)
    if err != nil {
        return fmt.Errorf("Failed to verify ip addresses: %v", err)
    }

    addrv4, _ := selectIPv4Address(addrsv4, config.AddressIPv4)

    // Verify that the bridge has an IPv4 address.
    if addrv4.IPNet == nil {
        return &ErrNoIPAddr{}
    }

    // Verify that the bridge IPv4 address matches the requested configuration.
    if config.AddressIPv4 != nil && !addrv4.IP.Equal(config.AddressIPv4.IP) {
        return &IPv4AddrNoMatchError{IP: addrv4.IP, CfgIP: config.AddressIPv4.IP}
    }

    return nil
}

func bridgeInterfaceExists(name string) (bool, error) {
    nlh := ns.NlHandle()
    link, err := nlh.LinkByName(name)
    if err != nil {
        if strings.Contains(err.Error(), "Link not found") {
            return false, nil
        }
        return false, fmt.Errorf("failed to check bridge interface existence: %v", err)
    }

    if link.Type() == "bridge" {
        return true, nil
    }
    return false, fmt.Errorf("existing interface %s is not a bridge", name)
}