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listen_addr.go
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listen_addr.go
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package cluster
import (
"errors"
"fmt"
"net"
)
var (
errNoSuchInterface = errors.New("no such interface")
errNoIP = errors.New("could not find the system's IP address")
errMustSpecifyListenAddr = errors.New("must specify a listening address because the address to advertise is not recognized as a system address, and a system's IP address to use could not be uniquely identified")
errBadListenAddr = errors.New("listen address must be an IP address or network interface (with optional port number)")
errBadAdvertiseAddr = errors.New("advertise address must be a non-zero IP address or network interface (with optional port number)")
errBadDefaultAdvertiseAddr = errors.New("default advertise address must be a non-zero IP address or network interface (without a port number)")
)
func resolveListenAddr(specifiedAddr string) (string, string, error) {
specifiedHost, specifiedPort, err := net.SplitHostPort(specifiedAddr)
if err != nil {
return "", "", fmt.Errorf("could not parse listen address %s", specifiedAddr)
}
// Does the host component match any of the interface names on the
// system? If so, use the address from that interface.
interfaceAddr, err := resolveInterfaceAddr(specifiedHost)
if err == nil {
return interfaceAddr.String(), specifiedPort, nil
}
if err != errNoSuchInterface {
return "", "", err
}
// If it's not an interface, it must be an IP (for now)
if net.ParseIP(specifiedHost) == nil {
return "", "", errBadListenAddr
}
return specifiedHost, specifiedPort, nil
}
func (c *Cluster) resolveAdvertiseAddr(advertiseAddr, listenAddrPort string) (string, string, error) {
// Approach:
// - If an advertise address is specified, use that. Resolve the
// interface's address if an interface was specified in
// advertiseAddr. Fill in the port from listenAddrPort if necessary.
// - If DefaultAdvertiseAddr is not empty, use that with the port from
// listenAddrPort. Resolve the interface's address from
// if an interface name was specified in DefaultAdvertiseAddr.
// - Otherwise, try to autodetect the system's address. Use the port in
// listenAddrPort with this address if autodetection succeeds.
if advertiseAddr != "" {
advertiseHost, advertisePort, err := net.SplitHostPort(advertiseAddr)
if err != nil {
// Not a host:port specification
advertiseHost = advertiseAddr
advertisePort = listenAddrPort
}
// Does the host component match any of the interface names on the
// system? If so, use the address from that interface.
interfaceAddr, err := resolveInterfaceAddr(advertiseHost)
if err == nil {
return interfaceAddr.String(), advertisePort, nil
}
if err != errNoSuchInterface {
return "", "", err
}
// If it's not an interface, it must be an IP (for now)
if ip := net.ParseIP(advertiseHost); ip == nil || ip.IsUnspecified() {
return "", "", errBadAdvertiseAddr
}
return advertiseHost, advertisePort, nil
}
if c.config.DefaultAdvertiseAddr != "" {
// Does the default advertise address component match any of the
// interface names on the system? If so, use the address from
// that interface.
interfaceAddr, err := resolveInterfaceAddr(c.config.DefaultAdvertiseAddr)
if err == nil {
return interfaceAddr.String(), listenAddrPort, nil
}
if err != errNoSuchInterface {
return "", "", err
}
// If it's not an interface, it must be an IP (for now)
if ip := net.ParseIP(c.config.DefaultAdvertiseAddr); ip == nil || ip.IsUnspecified() {
return "", "", errBadDefaultAdvertiseAddr
}
return c.config.DefaultAdvertiseAddr, listenAddrPort, nil
}
systemAddr, err := c.resolveSystemAddr()
if err != nil {
return "", "", err
}
return systemAddr.String(), listenAddrPort, nil
}
func resolveInterfaceAddr(specifiedInterface string) (net.IP, error) {
// Use a specific interface's IP address.
intf, err := net.InterfaceByName(specifiedInterface)
if err != nil {
return nil, errNoSuchInterface
}
addrs, err := intf.Addrs()
if err != nil {
return nil, err
}
var interfaceAddr4, interfaceAddr6 net.IP
for _, addr := range addrs {
ipAddr, ok := addr.(*net.IPNet)
if ok {
if ipAddr.IP.To4() != nil {
// IPv4
if interfaceAddr4 != nil {
return nil, fmt.Errorf("interface %s has more than one IPv4 address (%s and %s)", specifiedInterface, interfaceAddr4, ipAddr.IP)
}
interfaceAddr4 = ipAddr.IP
} else {
// IPv6
if interfaceAddr6 != nil {
return nil, fmt.Errorf("interface %s has more than one IPv6 address (%s and %s)", specifiedInterface, interfaceAddr6, ipAddr.IP)
}
interfaceAddr6 = ipAddr.IP
}
}
}
if interfaceAddr4 == nil && interfaceAddr6 == nil {
return nil, fmt.Errorf("interface %s has no usable IPv4 or IPv6 address", specifiedInterface)
}
// In the case that there's exactly one IPv4 address
// and exactly one IPv6 address, favor IPv4 over IPv6.
if interfaceAddr4 != nil {
return interfaceAddr4, nil
}
return interfaceAddr6, nil
}
func (c *Cluster) resolveSystemAddrViaSubnetCheck() (net.IP, error) {
// Use the system's only IP address, or fail if there are
// multiple addresses to choose from. Skip interfaces which
// are managed by docker via subnet check.
interfaces, err := net.Interfaces()
if err != nil {
return nil, err
}
var systemAddr net.IP
var systemInterface string
// List Docker-managed subnets
v4Subnets, v6Subnets := c.config.NetworkSubnetsProvider.Subnets()
ifaceLoop:
for _, intf := range interfaces {
// Skip inactive interfaces and loopback interfaces
if (intf.Flags&net.FlagUp == 0) || (intf.Flags&net.FlagLoopback) != 0 {
continue
}
addrs, err := intf.Addrs()
if err != nil {
continue
}
var interfaceAddr4, interfaceAddr6 net.IP
for _, addr := range addrs {
ipAddr, ok := addr.(*net.IPNet)
// Skip loopback and link-local addresses
if !ok || !ipAddr.IP.IsGlobalUnicast() {
continue
}
if ipAddr.IP.To4() != nil {
// IPv4
// Ignore addresses in subnets that are managed by Docker.
for _, subnet := range v4Subnets {
if subnet.Contains(ipAddr.IP) {
continue ifaceLoop
}
}
if interfaceAddr4 != nil {
return nil, errMultipleIPs(intf.Name, intf.Name, interfaceAddr4, ipAddr.IP)
}
interfaceAddr4 = ipAddr.IP
} else {
// IPv6
// Ignore addresses in subnets that are managed by Docker.
for _, subnet := range v6Subnets {
if subnet.Contains(ipAddr.IP) {
continue ifaceLoop
}
}
if interfaceAddr6 != nil {
return nil, errMultipleIPs(intf.Name, intf.Name, interfaceAddr6, ipAddr.IP)
}
interfaceAddr6 = ipAddr.IP
}
}
// In the case that this interface has exactly one IPv4 address
// and exactly one IPv6 address, favor IPv4 over IPv6.
if interfaceAddr4 != nil {
if systemAddr != nil {
return nil, errMultipleIPs(systemInterface, intf.Name, systemAddr, interfaceAddr4)
}
systemAddr = interfaceAddr4
systemInterface = intf.Name
} else if interfaceAddr6 != nil {
if systemAddr != nil {
return nil, errMultipleIPs(systemInterface, intf.Name, systemAddr, interfaceAddr6)
}
systemAddr = interfaceAddr6
systemInterface = intf.Name
}
}
if systemAddr == nil {
return nil, errNoIP
}
return systemAddr, nil
}
func listSystemIPs() []net.IP {
interfaces, err := net.Interfaces()
if err != nil {
return nil
}
var systemAddrs []net.IP
for _, intf := range interfaces {
addrs, err := intf.Addrs()
if err != nil {
continue
}
for _, addr := range addrs {
ipAddr, ok := addr.(*net.IPNet)
if ok {
systemAddrs = append(systemAddrs, ipAddr.IP)
}
}
}
return systemAddrs
}
func errMultipleIPs(interfaceA, interfaceB string, addrA, addrB net.IP) error {
if interfaceA == interfaceB {
return fmt.Errorf("could not choose an IP address to advertise since this system has multiple addresses on interface %s (%s and %s)", interfaceA, addrA, addrB)
}
return fmt.Errorf("could not choose an IP address to advertise since this system has multiple addresses on different interfaces (%s on %s and %s on %s)", addrA, interfaceA, addrB, interfaceB)
}