AdGuardHome/internal/aghnet/net.go

428 lines
11 KiB
Go

// Package aghnet contains some utilities for networking.
package aghnet
import (
"encoding/json"
"errors"
"fmt"
"net"
"os"
"os/exec"
"runtime"
"strconv"
"strings"
"syscall"
"time"
"github.com/AdguardTeam/AdGuardHome/internal/agherr"
"github.com/AdguardTeam/AdGuardHome/internal/aghstrings"
"github.com/AdguardTeam/golibs/log"
)
// ErrNoStaticIPInfo is returned by IfaceHasStaticIP when no information about
// the IP being static is available.
const ErrNoStaticIPInfo agherr.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
}
// NetInterface represents an entry of network interfaces map.
type NetInterface struct {
MTU int `json:"mtu"`
Name string `json:"name"`
HardwareAddr net.HardwareAddr `json:"hardware_address"`
Flags net.Flags `json:"flags"`
// Array with the network interface addresses.
Addresses []net.IP `json:"ip_addresses,omitempty"`
// Array with IP networks for this network interface.
Subnets []*net.IPNet `json:"-"`
}
// 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.New("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
}
// CheckPortAvailable - check if TCP port is available
func CheckPortAvailable(host net.IP, port int) error {
ln, err := net.Listen("tcp", net.JoinHostPort(host.String(), strconv.Itoa(port)))
if err != nil {
return err
}
_ = ln.Close()
// It seems that net.Listener.Close() doesn't close file descriptors right away.
// We wait for some time and hope that this fd will be closed.
time.Sleep(100 * time.Millisecond)
return nil
}
// CheckPacketPortAvailable - check if UDP port is available
func CheckPacketPortAvailable(host net.IP, port int) error {
ln, err := net.ListenPacket("udp", net.JoinHostPort(host.String(), strconv.Itoa(port)))
if err != nil {
return err
}
_ = ln.Close()
// It seems that net.Listener.Close() doesn't close file descriptors right away.
// We wait for some time and hope that this fd will be closed.
time.Sleep(100 * time.Millisecond)
return err
}
// ErrorIsAddrInUse - check if error is "address already in use"
func ErrorIsAddrInUse(err error) bool {
errOpError, ok := err.(*net.OpError)
if !ok {
return false
}
errSyscallError, ok := errOpError.Err.(*os.SyscallError)
if !ok {
return false
}
errErrno, ok := errSyscallError.Err.(syscall.Errno)
if !ok {
return false
}
if runtime.GOOS == "windows" {
const WSAEADDRINUSE = 10048
return errErrno == WSAEADDRINUSE
}
return errErrno == syscall.EADDRINUSE
}
// 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
}
// TODO(e.burkov): Inspect the charToHex, ipParseARPA6, ipReverse and
// UnreverseAddr and maybe refactor it.
// charToHex converts character to a hexadecimal.
func charToHex(n byte) int8 {
if n >= '0' && n <= '9' {
return int8(n) - '0'
} else if (n|0x20) >= 'a' && (n|0x20) <= 'f' {
return (int8(n) | 0x20) - 'a' + 10
}
return -1
}
// ipParseARPA6 parse IPv6 reverse address
func ipParseARPA6(s string) (ip6 net.IP) {
if len(s) != 63 {
return nil
}
ip6 = make(net.IP, 16)
for i := 0; i != 64; i += 4 {
// parse "0.1."
n := charToHex(s[i])
n2 := charToHex(s[i+2])
if s[i+1] != '.' || (i != 60 && s[i+3] != '.') ||
n < 0 || n2 < 0 {
return nil
}
ip6[16-i/4-1] = byte(n2<<4) | byte(n&0x0f)
}
return ip6
}
// ipReverse inverts byte order of ip.
func ipReverse(ip net.IP) (rev net.IP) {
ipLen := len(ip)
rev = make(net.IP, ipLen)
for i, b := range ip {
rev[ipLen-i-1] = b
}
return rev
}
// ARPA addresses' suffixes.
const (
arpaV4Suffix = ".in-addr.arpa"
arpaV6Suffix = ".ip6.arpa"
)
// UnreverseAddr tries to convert reversed ARPA to a normal IP address.
func UnreverseAddr(arpa string) (unreversed net.IP) {
// Unify the input data.
arpa = strings.TrimSuffix(arpa, ".")
arpa = strings.ToLower(arpa)
if strings.HasSuffix(arpa, arpaV4Suffix) {
ip := strings.TrimSuffix(arpa, arpaV4Suffix)
ip4 := net.ParseIP(ip).To4()
if ip4 == nil {
return nil
}
return ipReverse(ip4)
} else if strings.HasSuffix(arpa, arpaV6Suffix) {
ip := strings.TrimSuffix(arpa, arpaV6Suffix)
return ipParseARPA6(ip)
}
// The suffix unrecognizable.
return nil
}
// The length of extreme cases of arpa formatted addresses.
//
// The example of IPv4 with maximum length:
//
// 49.91.20.104.in-addr.arpa
//
// The example of IPv6 with maximum length:
//
// 1.3.b.5.4.1.8.6.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.0.0.0.7.4.6.0.6.2.ip6.arpa
//
const (
arpaV4MaxLen = len("000.000.000.000") + len(arpaV4Suffix)
arpaV6MaxLen = len("0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0") +
len(arpaV6Suffix)
)
// ReverseAddr returns the ARPA hostname of the ip suitable for reverse DNS
// (PTR) record lookups. This is the modified version of ReverseAddr from
// github.com/miekg/dns package with no error among returned values.
func ReverseAddr(ip net.IP) (arpa string) {
const dot = "."
var strLen int
var suffix string
var writeByte func(val byte)
b := &strings.Builder{}
if ip4 := ip.To4(); ip4 != nil {
strLen, suffix = arpaV4MaxLen, arpaV4Suffix[1:]
ip = ip4
writeByte = func(val byte) {
aghstrings.WriteToBuilder(b, strconv.Itoa(int(val)), dot)
}
} else if ip6 := ip.To16(); ip6 != nil {
strLen, suffix = arpaV6MaxLen, arpaV6Suffix[1:]
ip = ip6
writeByte = func(val byte) {
aghstrings.WriteToBuilder(
b,
strconv.FormatUint(uint64(val&0xF), 16),
dot,
strconv.FormatUint(uint64(val>>4), 16),
dot,
)
}
} else {
return ""
}
b.Grow(strLen)
for i := len(ip) - 1; i >= 0; i-- {
writeByte(ip[i])
}
aghstrings.WriteToBuilder(b, suffix)
return b.String()
}
// 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
}