github.com/jfrazelle/docker@v1.1.2-0.20210712172922-bf78e25fe508/libnetwork/drivers/bridge/setup_ipv4.go (about)

     1  // +build linux
     2  
     3  package bridge
     4  
     5  import (
     6  	"errors"
     7  	"fmt"
     8  	"io/ioutil"
     9  	"net"
    10  	"path/filepath"
    11  
    12  	"github.com/docker/docker/libnetwork/types"
    13  	"github.com/sirupsen/logrus"
    14  	"github.com/vishvananda/netlink"
    15  )
    16  
    17  func selectIPv4Address(addresses []netlink.Addr, selector *net.IPNet) (netlink.Addr, error) {
    18  	if len(addresses) == 0 {
    19  		return netlink.Addr{}, errors.New("unable to select an address as the address pool is empty")
    20  	}
    21  	if selector != nil {
    22  		for _, addr := range addresses {
    23  			if selector.Contains(addr.IP) {
    24  				return addr, nil
    25  			}
    26  		}
    27  	}
    28  	return addresses[0], nil
    29  }
    30  
    31  func setupBridgeIPv4(config *networkConfiguration, i *bridgeInterface) error {
    32  	if !config.InhibitIPv4 {
    33  		addrv4List, _, err := i.addresses()
    34  		if err != nil {
    35  			return fmt.Errorf("failed to retrieve bridge interface addresses: %v", err)
    36  		}
    37  
    38  		addrv4, _ := selectIPv4Address(addrv4List, config.AddressIPv4)
    39  
    40  		if !types.CompareIPNet(addrv4.IPNet, config.AddressIPv4) {
    41  			if addrv4.IPNet != nil {
    42  				if err := i.nlh.AddrDel(i.Link, &addrv4); err != nil {
    43  					return fmt.Errorf("failed to remove current ip address from bridge: %v", err)
    44  				}
    45  			}
    46  			logrus.Debugf("Assigning address to bridge interface %s: %s", config.BridgeName, config.AddressIPv4)
    47  			if err := i.nlh.AddrAdd(i.Link, &netlink.Addr{IPNet: config.AddressIPv4}); err != nil {
    48  				return &IPv4AddrAddError{IP: config.AddressIPv4, Err: err}
    49  			}
    50  		}
    51  	}
    52  
    53  	// Store bridge network and default gateway
    54  	i.bridgeIPv4 = config.AddressIPv4
    55  	i.gatewayIPv4 = config.AddressIPv4.IP
    56  
    57  	return nil
    58  }
    59  
    60  func setupGatewayIPv4(config *networkConfiguration, i *bridgeInterface) error {
    61  	if !i.bridgeIPv4.Contains(config.DefaultGatewayIPv4) {
    62  		return &ErrInvalidGateway{}
    63  	}
    64  
    65  	// Store requested default gateway
    66  	i.gatewayIPv4 = config.DefaultGatewayIPv4
    67  
    68  	return nil
    69  }
    70  
    71  func setupLoopbackAddressesRouting(config *networkConfiguration, i *bridgeInterface) error {
    72  	sysPath := filepath.Join("/proc/sys/net/ipv4/conf", config.BridgeName, "route_localnet")
    73  	ipv4LoRoutingData, err := ioutil.ReadFile(sysPath)
    74  	if err != nil {
    75  		return fmt.Errorf("Cannot read IPv4 local routing setup: %v", err)
    76  	}
    77  	// Enable loopback addresses routing only if it isn't already enabled
    78  	if ipv4LoRoutingData[0] != '1' {
    79  		if err := ioutil.WriteFile(sysPath, []byte{'1', '\n'}, 0644); err != nil {
    80  			return fmt.Errorf("Unable to enable local routing for hairpin mode: %v", err)
    81  		}
    82  	}
    83  	return nil
    84  }