AdGuardHome/internal/aghnet/net.go

284 lines
7.3 KiB
Go

// Package aghnet contains some utilities for networking.
package aghnet
import (
"encoding/json"
"fmt"
"io"
"net"
"os/exec"
"strings"
"syscall"
"github.com/AdguardTeam/golibs/errors"
"github.com/AdguardTeam/golibs/log"
"github.com/AdguardTeam/golibs/netutil"
)
// ErrNoStaticIPInfo is returned by IfaceHasStaticIP when no information about
// the IP being static is available.
const ErrNoStaticIPInfo errors.Error = "no information about static ip"
// IfaceHasStaticIP checks if interface is configured to have static IP address.
// If it can't give a definitive answer, it returns false and an error for which
// errors.Is(err, ErrNoStaticIPInfo) is true.
func IfaceHasStaticIP(ifaceName string) (has bool, err error) {
return ifaceHasStaticIP(ifaceName)
}
// IfaceSetStaticIP sets static IP address for network interface.
func IfaceSetStaticIP(ifaceName string) (err error) {
return ifaceSetStaticIP(ifaceName)
}
// GatewayIP returns IP address of interface's gateway.
func GatewayIP(ifaceName string) net.IP {
cmd := exec.Command("ip", "route", "show", "dev", ifaceName)
log.Tracef("executing %s %v", cmd.Path, cmd.Args)
d, err := cmd.Output()
if err != nil || cmd.ProcessState.ExitCode() != 0 {
return nil
}
fields := strings.Fields(string(d))
// The meaningful "ip route" command output should contain the word
// "default" at first field and default gateway IP address at third
// field.
if len(fields) < 3 || fields[0] != "default" {
return nil
}
return net.ParseIP(fields[2])
}
// CanBindPort checks if we can bind to the given port.
func CanBindPort(port int) (can bool, err error) {
var addr *net.TCPAddr
addr, err = net.ResolveTCPAddr("tcp", fmt.Sprintf("127.0.0.1:%d", port))
if err != nil {
return false, err
}
var listener *net.TCPListener
listener, err = net.ListenTCP("tcp", addr)
if err != nil {
return false, err
}
_ = listener.Close()
return true, nil
}
// CanBindPrivilegedPorts checks if current process can bind to privileged
// ports.
func CanBindPrivilegedPorts() (can bool, err error) {
return canBindPrivilegedPorts()
}
// NetInterface represents an entry of network interfaces map.
type NetInterface struct {
// Addresses are the network interface addresses.
Addresses []net.IP `json:"ip_addresses,omitempty"`
// Subnets are the IP networks for this network interface.
Subnets []*net.IPNet `json:"-"`
Name string `json:"name"`
HardwareAddr net.HardwareAddr `json:"hardware_address"`
Flags net.Flags `json:"flags"`
MTU int `json:"mtu"`
}
// MarshalJSON implements the json.Marshaler interface for NetInterface.
func (iface NetInterface) MarshalJSON() ([]byte, error) {
type netInterface NetInterface
return json.Marshal(&struct {
HardwareAddr string `json:"hardware_address"`
Flags string `json:"flags"`
netInterface
}{
HardwareAddr: iface.HardwareAddr.String(),
Flags: iface.Flags.String(),
netInterface: netInterface(iface),
})
}
// GetValidNetInterfacesForWeb returns interfaces that are eligible for DNS and WEB only
// we do not return link-local addresses here
func GetValidNetInterfacesForWeb() ([]*NetInterface, error) {
ifaces, err := net.Interfaces()
if err != nil {
return nil, fmt.Errorf("couldn't get interfaces: %w", err)
}
if len(ifaces) == 0 {
return nil, errors.Error("couldn't find any legible interface")
}
var netInterfaces []*NetInterface
for _, iface := range ifaces {
var addrs []net.Addr
addrs, err = iface.Addrs()
if err != nil {
return nil, fmt.Errorf("failed to get addresses for interface %s: %w", iface.Name, err)
}
netIface := &NetInterface{
MTU: iface.MTU,
Name: iface.Name,
HardwareAddr: iface.HardwareAddr,
Flags: iface.Flags,
}
// Collect network interface addresses.
for _, addr := range addrs {
ipNet, ok := addr.(*net.IPNet)
if !ok {
// Should be net.IPNet, this is weird.
return nil, fmt.Errorf("got iface.Addrs() element %s that is not net.IPNet, it is %T", addr, addr)
}
// Ignore link-local.
if ipNet.IP.IsLinkLocalUnicast() {
continue
}
netIface.Addresses = append(netIface.Addresses, ipNet.IP)
netIface.Subnets = append(netIface.Subnets, ipNet)
}
// Discard interfaces with no addresses.
if len(netIface.Addresses) != 0 {
netInterfaces = append(netInterfaces, netIface)
}
}
return netInterfaces, nil
}
// GetInterfaceByIP returns the name of interface containing provided ip.
func GetInterfaceByIP(ip net.IP) string {
ifaces, err := GetValidNetInterfacesForWeb()
if err != nil {
return ""
}
for _, iface := range ifaces {
for _, addr := range iface.Addresses {
if ip.Equal(addr) {
return iface.Name
}
}
}
return ""
}
// GetSubnet returns pointer to net.IPNet for the specified interface or nil if
// the search fails.
func GetSubnet(ifaceName string) *net.IPNet {
netIfaces, err := GetValidNetInterfacesForWeb()
if err != nil {
log.Error("Could not get network interfaces info: %v", err)
return nil
}
for _, netIface := range netIfaces {
if netIface.Name == ifaceName && len(netIface.Subnets) > 0 {
return netIface.Subnets[0]
}
}
return nil
}
// CheckPort checks if the port is available for binding.
func CheckPort(network string, ip net.IP, port int) (err error) {
var c io.Closer
addr := netutil.IPPort{IP: ip, Port: port}.String()
switch network {
case "tcp":
c, err = net.Listen(network, addr)
case "udp":
c, err = net.ListenPacket(network, addr)
default:
return nil
}
return errors.WithDeferred(err, closePortChecker(c))
}
// IsAddrInUse checks if err is about unsuccessful address binding.
func IsAddrInUse(err error) (ok bool) {
var sysErr syscall.Errno
if !errors.As(err, &sysErr) {
return false
}
return isAddrInUse(sysErr)
}
// SplitHost is a wrapper for net.SplitHostPort for the cases when the hostport
// does not necessarily contain a port.
func SplitHost(hostport string) (host string, err error) {
host, _, err = net.SplitHostPort(hostport)
if err != nil {
// Check for the missing port error. If it is that error, just
// use the host as is.
//
// See the source code for net.SplitHostPort.
const missingPort = "missing port in address"
addrErr := &net.AddrError{}
if !errors.As(err, &addrErr) || addrErr.Err != missingPort {
return "", err
}
host = hostport
}
return host, nil
}
// CollectAllIfacesAddrs returns the slice of all network interfaces IP
// addresses without port number.
func CollectAllIfacesAddrs() (addrs []string, err error) {
var ifaces []net.Interface
ifaces, err = net.Interfaces()
if err != nil {
return nil, fmt.Errorf("getting network interfaces: %w", err)
}
for _, iface := range ifaces {
var ifaceAddrs []net.Addr
ifaceAddrs, err = iface.Addrs()
if err != nil {
return nil, fmt.Errorf("getting addresses for %q: %w", iface.Name, err)
}
for _, addr := range ifaceAddrs {
cidr := addr.String()
var ip net.IP
ip, _, err = net.ParseCIDR(cidr)
if err != nil {
return nil, fmt.Errorf("parsing cidr: %w", err)
}
addrs = append(addrs, ip.String())
}
}
return addrs, nil
}
// BroadcastFromIPNet calculates the broadcast IP address for n.
func BroadcastFromIPNet(n *net.IPNet) (dc net.IP) {
dc = netutil.CloneIP(n.IP)
mask := n.Mask
if mask == nil {
mask = dc.DefaultMask()
}
for i, b := range mask {
dc[i] |= ^b
}
return dc
}