Vladimir Avtsenov
8369de6845
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570 lines
14 KiB
Go
570 lines
14 KiB
Go
package kvas2
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import (
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"context"
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"encoding/binary"
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"errors"
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"fmt"
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"math/rand"
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"net"
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"os"
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"strconv"
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"strings"
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"time"
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"kvas2/dns-mitm-proxy"
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"kvas2/group"
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"kvas2/models"
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"kvas2/netfilter-helper"
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"kvas2/records"
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"github.com/miekg/dns"
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"github.com/rs/zerolog/log"
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"github.com/vishvananda/netlink"
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"github.com/vishvananda/netlink/nl"
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)
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var (
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ErrAlreadyRunning = errors.New("already running")
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ErrGroupIDConflict = errors.New("group id conflict")
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ErrRuleIDConflict = errors.New("rule id conflict")
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)
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func randomId() [4]byte {
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id := make([]byte, 4)
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binary.BigEndian.PutUint32(id, rand.Uint32())
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return [4]byte(id)
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}
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type Config struct {
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AdditionalTTL uint32
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ChainPrefix string
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IPSetPrefix string
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LinkName string
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TargetDNSServerAddress string
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TargetDNSServerPort uint16
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ListenDNSPort uint16
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}
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type App struct {
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Config Config
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DNSMITM *dnsMitmProxy.DNSMITMProxy
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NetfilterHelper4 *netfilterHelper.NetfilterHelper
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NetfilterHelper6 *netfilterHelper.NetfilterHelper
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Records *records.Records
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Groups []*group.Group
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Link netlink.Link
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isRunning bool
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dnsOverrider4 *netfilterHelper.PortRemap
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dnsOverrider6 *netfilterHelper.PortRemap
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}
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func (a *App) handleLink(event netlink.LinkUpdate) {
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switch event.Change {
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case 0x00000001:
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log.Trace().
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Str("interface", event.Link.Attrs().Name).
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Int("change", int(event.Change)).
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Msg("interface event")
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ifaceName := event.Link.Attrs().Name
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for _, group := range a.Groups {
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if group.Interface != ifaceName {
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continue
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}
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err := group.LinkUpdateHook(event)
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if err != nil {
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log.Error().Str("group", group.ID.String()).Err(err).Msg("error while handling interface up")
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}
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}
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case 0xFFFFFFFF:
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switch event.Header.Type {
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case 16:
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log.Debug().
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Str("interface", event.Link.Attrs().Name).
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Int("type", int(event.Header.Type)).
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Msg("interface add")
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case 17:
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log.Debug().
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Str("interface", event.Link.Attrs().Name).
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Int("type", int(event.Header.Type)).
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Msg("interface del")
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}
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}
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}
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func (a *App) start(ctx context.Context) (err error) {
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newCtx, cancel := context.WithCancel(ctx)
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defer cancel()
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errChan := make(chan error)
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/*
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DNS Proxy
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*/
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go func() {
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addr, err := net.ResolveUDPAddr("udp", "[::]:"+strconv.Itoa(int(a.Config.ListenDNSPort)))
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if err != nil {
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errChan <- fmt.Errorf("failed to resolve udp address: %v", err)
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return
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}
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err = a.DNSMITM.ListenUDP(newCtx, addr)
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if err != nil {
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errChan <- fmt.Errorf("failed to serve DNS UDP proxy: %v", err)
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return
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}
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}()
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go func() {
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addr, err := net.ResolveTCPAddr("tcp", "[::]:"+strconv.Itoa(int(a.Config.ListenDNSPort)))
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if err != nil {
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errChan <- fmt.Errorf("failed to resolve tcp address: %v", err)
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return
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}
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err = a.DNSMITM.ListenTCP(newCtx, addr)
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if err != nil {
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errChan <- fmt.Errorf("failed to serve DNS TCP proxy: %v", err)
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return
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}
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}()
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addrList, err := netlink.AddrList(a.Link, nl.FAMILY_ALL)
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if err != nil {
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return fmt.Errorf("failed to list address of interface: %w", err)
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}
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a.dnsOverrider4 = a.NetfilterHelper4.PortRemap(fmt.Sprintf("%sDNSOR", a.Config.ChainPrefix), 53, a.Config.ListenDNSPort, addrList)
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err = a.dnsOverrider4.Enable()
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if err != nil {
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return fmt.Errorf("failed to override DNS (IPv4): %v", err)
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}
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defer func() { _ = a.dnsOverrider4.Disable() }()
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a.dnsOverrider6 = a.NetfilterHelper6.PortRemap(fmt.Sprintf("%sDNSOR", a.Config.ChainPrefix), 53, a.Config.ListenDNSPort, addrList)
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err = a.dnsOverrider6.Enable()
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if err != nil {
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return fmt.Errorf("failed to override DNS (IPv6): %v", err)
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}
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defer func() { _ = a.dnsOverrider6.Disable() }()
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/*
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Groups
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*/
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for _, group := range a.Groups {
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err = group.Enable()
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if err != nil {
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return fmt.Errorf("failed to enable group: %w", err)
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}
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}
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defer func() {
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for _, group := range a.Groups {
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_ = group.Disable()
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}
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}()
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/*
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Socket (for netfilter.d events)
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*/
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socketPath := "/opt/var/run/kvas2.sock"
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err = os.Remove(socketPath)
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if err != nil && !errors.Is(err, os.ErrNotExist) {
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return fmt.Errorf("failed to remove existed UNIX socket: %w", err)
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}
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socket, err := net.Listen("unix", socketPath)
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if err != nil {
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return fmt.Errorf("error while serve UNIX socket: %v", err)
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}
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defer func() {
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_ = socket.Close()
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_ = os.Remove(socketPath)
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}()
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go func() {
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for {
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if newCtx.Err() != nil {
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return
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}
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conn, err := socket.Accept()
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if err != nil {
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if !strings.Contains(err.Error(), "use of closed network connection") {
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log.Error().Err(err).Msg("error while listening unix socket")
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}
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break
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}
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go func(conn net.Conn) {
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defer func() { _ = conn.Close() }()
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buf := make([]byte, 1024)
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n, err := conn.Read(buf)
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if err != nil {
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return
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}
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args := strings.Split(string(buf[:n]), ":")
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if len(args) == 3 && args[0] == "netfilter.d" {
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log.Debug().Str("table", args[2]).Msg("netfilter.d event")
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err = a.dnsOverrider4.NetfilterDHook(args[2])
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if err != nil {
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log.Error().Err(err).Msg("error while fixing iptables after netfilter.d")
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}
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err = a.dnsOverrider6.NetfilterDHook(args[2])
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if err != nil {
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log.Error().Err(err).Msg("error while fixing iptables after netfilter.d")
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}
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for _, group := range a.Groups {
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err := group.NetfilterDHook(args[2])
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if err != nil {
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log.Error().Err(err).Msg("error while fixing iptables after netfilter.d")
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}
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}
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}
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}(conn)
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}
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}()
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/*
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Interface updates
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*/
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linkUpdateChannel := make(chan netlink.LinkUpdate)
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linkUpdateDone := make(chan struct{})
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err = netlink.LinkSubscribe(linkUpdateChannel, linkUpdateDone)
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if err != nil {
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return fmt.Errorf("failed to subscribe to link updates: %w", err)
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}
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defer close(linkUpdateDone)
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/*
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Global loop
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*/
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for {
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select {
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case event := <-linkUpdateChannel:
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a.handleLink(event)
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case err := <-errChan:
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return err
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case <-ctx.Done():
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return nil
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}
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}
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}
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func (a *App) Start(ctx context.Context) (err error) {
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if a.isRunning {
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return ErrAlreadyRunning
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}
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a.isRunning = true
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defer func() {
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a.isRunning = false
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}()
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defer func() {
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if r := recover(); r != nil {
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var ok bool
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if err, ok = r.(error); !ok {
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err = fmt.Errorf("%v", r)
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}
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err = fmt.Errorf("recovered error: %w", err)
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}
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}()
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err = a.start(ctx)
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return err
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}
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func (a *App) AddGroup(groupModel *models.Group) error {
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for _, group := range a.Groups {
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if groupModel.ID == group.ID {
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return ErrGroupIDConflict
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}
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}
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dup := make(map[[4]byte]struct{})
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for _, rule := range groupModel.Rules {
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if _, exists := dup[rule.ID]; exists {
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return ErrRuleIDConflict
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}
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dup[rule.ID] = struct{}{}
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}
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grp, err := group.NewGroup(groupModel, a.NetfilterHelper4, a.Config.ChainPrefix, a.Config.IPSetPrefix)
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if err != nil {
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return fmt.Errorf("failed to create group: %w", err)
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}
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a.Groups = append(a.Groups, grp)
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log.Debug().Str("id", grp.ID.String()).Str("name", grp.Name).Msg("added group")
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return grp.Sync(a.Records)
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}
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func (a *App) ListInterfaces() ([]net.Interface, error) {
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interfaceNames := make([]net.Interface, 0)
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interfaces, err := net.Interfaces()
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if err != nil {
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return nil, fmt.Errorf("failed to get interfaces: %w", err)
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}
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for _, iface := range interfaces {
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if iface.Flags&net.FlagPointToPoint == 0 {
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continue
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}
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interfaceNames = append(interfaceNames, iface)
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}
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return interfaceNames, nil
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}
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func (a *App) processARecord(aRecord dns.A, clientAddr net.Addr, network *string) {
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var clientAddrStr, networkStr string
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if clientAddr != nil {
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clientAddrStr = clientAddr.String()
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}
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if network != nil {
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networkStr = *network
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}
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log.Trace().
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Str("name", aRecord.Hdr.Name).
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Str("address", aRecord.A.String()).
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Int("ttl", int(aRecord.Hdr.Ttl)).
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Str("clientAddr", clientAddrStr).
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Str("network", networkStr).
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Msg("processing a record")
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ttlDuration := aRecord.Hdr.Ttl + a.Config.AdditionalTTL
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a.Records.AddARecord(aRecord.Hdr.Name[:len(aRecord.Hdr.Name)-1], aRecord.A, ttlDuration)
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names := a.Records.GetAliases(aRecord.Hdr.Name[:len(aRecord.Hdr.Name)-1])
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for _, group := range a.Groups {
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Rule:
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for _, domain := range group.Rules {
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if !domain.IsEnabled() {
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continue
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}
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for _, name := range names {
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if !domain.IsMatch(name) {
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continue
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}
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// TODO: Check already existed
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err := group.AddIP(aRecord.A, ttlDuration)
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if err != nil {
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log.Error().
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Str("address", aRecord.A.String()).
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Err(err).
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Msg("failed to add address")
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} else {
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log.Debug().
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Str("address", aRecord.A.String()).
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Str("aRecordDomain", aRecord.Hdr.Name).
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Str("cNameDomain", name).
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Msg("add address")
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}
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break Rule
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}
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}
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}
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}
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func (a *App) processCNameRecord(cNameRecord dns.CNAME, clientAddr net.Addr, network *string) {
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var clientAddrStr, networkStr string
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if clientAddr != nil {
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clientAddrStr = clientAddr.String()
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}
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if network != nil {
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networkStr = *network
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}
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log.Trace().
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Str("name", cNameRecord.Hdr.Name).
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Str("cname", cNameRecord.Target).
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Int("ttl", int(cNameRecord.Hdr.Ttl)).
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Str("clientAddr", clientAddrStr).
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Str("network", networkStr).
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Msg("processing cname record")
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ttlDuration := cNameRecord.Hdr.Ttl + a.Config.AdditionalTTL
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a.Records.AddCNameRecord(cNameRecord.Hdr.Name[:len(cNameRecord.Hdr.Name)-1], cNameRecord.Target[:len(cNameRecord.Target)-1], ttlDuration)
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// TODO: Optimization
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now := time.Now()
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aRecords := a.Records.GetARecords(cNameRecord.Hdr.Name[:len(cNameRecord.Hdr.Name)-1])
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names := a.Records.GetAliases(cNameRecord.Hdr.Name[:len(cNameRecord.Hdr.Name)-1])
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for _, group := range a.Groups {
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Rule:
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for _, domain := range group.Rules {
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if !domain.IsEnabled() {
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continue
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}
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for _, name := range names {
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if !domain.IsMatch(name) {
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continue
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}
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for _, aRecord := range aRecords {
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err := group.AddIP(aRecord.Address, uint32(now.Sub(aRecord.Deadline).Seconds()))
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if err != nil {
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log.Error().
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Str("address", aRecord.Address.String()).
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Err(err).
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Msg("failed to add address")
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} else {
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log.Debug().
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Str("address", aRecord.Address.String()).
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Str("cNameDomain", name).
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Msg("add address")
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}
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}
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continue Rule
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}
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}
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}
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}
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func (a *App) handleRecord(rr dns.RR, clientAddr net.Addr, network *string) {
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switch v := rr.(type) {
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case *dns.A:
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a.processARecord(*v, clientAddr, network)
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case *dns.CNAME:
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a.processCNameRecord(*v, clientAddr, network)
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default:
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}
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}
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func (a *App) handleMessage(msg dns.Msg, clientAddr net.Addr, network *string) {
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for _, rr := range msg.Answer {
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a.handleRecord(rr, clientAddr, network)
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}
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}
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func (a *App) ImportConfig(cfg models.ConfigFile) error {
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a.Config = Config{
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AdditionalTTL: cfg.AppConfig.AdditionalTTL,
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ChainPrefix: cfg.AppConfig.ChainPrefix,
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IPSetPrefix: cfg.AppConfig.IPSetPrefix,
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LinkName: cfg.AppConfig.LinkName,
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TargetDNSServerAddress: cfg.AppConfig.TargetDNSServerAddress,
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TargetDNSServerPort: cfg.AppConfig.TargetDNSServerPort,
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ListenDNSPort: cfg.AppConfig.ListenDNSPort,
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}
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return nil
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}
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func (a *App) ExportConfig() models.ConfigFile {
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groups := make([]models.Group, len(a.Groups))
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for idx, group := range a.Groups {
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groups[idx] = *group.Group
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}
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return models.ConfigFile{
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AppConfig: models.AppConfig{
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AdditionalTTL: a.Config.AdditionalTTL,
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ChainPrefix: a.Config.ChainPrefix,
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IPSetPrefix: a.Config.IPSetPrefix,
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LinkName: a.Config.LinkName,
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TargetDNSServerAddress: a.Config.TargetDNSServerAddress,
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TargetDNSServerPort: a.Config.TargetDNSServerPort,
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ListenDNSPort: a.Config.ListenDNSPort,
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},
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Groups: groups,
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}
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}
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func New(config models.ConfigFile) (*App, error) {
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var err error
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app := &App{}
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app.Config = Config{
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AdditionalTTL: config.AppConfig.AdditionalTTL,
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ChainPrefix: config.AppConfig.ChainPrefix,
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IPSetPrefix: config.AppConfig.IPSetPrefix,
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LinkName: config.AppConfig.LinkName,
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TargetDNSServerAddress: config.AppConfig.TargetDNSServerAddress,
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TargetDNSServerPort: config.AppConfig.TargetDNSServerPort,
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ListenDNSPort: config.AppConfig.ListenDNSPort,
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}
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app.DNSMITM = dnsMitmProxy.New()
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app.DNSMITM.TargetDNSServerAddress = app.Config.TargetDNSServerAddress
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app.DNSMITM.TargetDNSServerPort = app.Config.TargetDNSServerPort
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app.DNSMITM.RequestHook = func(clientAddr net.Addr, reqMsg dns.Msg, network string) (*dns.Msg, *dns.Msg, error) {
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// TODO: Need to understand why it not works in proxy mode
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if len(reqMsg.Question) == 1 && reqMsg.Question[0].Qtype == dns.TypePTR {
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respMsg := &dns.Msg{
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MsgHdr: dns.MsgHdr{
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Id: reqMsg.Id,
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Response: true,
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RecursionAvailable: true,
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Rcode: dns.RcodeNameError,
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},
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Question: reqMsg.Question,
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}
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return nil, respMsg, nil
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}
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return nil, nil, nil
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}
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app.DNSMITM.ResponseHook = func(clientAddr net.Addr, reqMsg dns.Msg, respMsg dns.Msg, network string) (*dns.Msg, error) {
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// TODO: Make it optional
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var idx int
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for _, a := range respMsg.Answer {
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if a.Header().Rrtype == dns.TypeAAAA {
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continue
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}
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respMsg.Answer[idx] = a
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idx++
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}
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respMsg.Answer = respMsg.Answer[:idx]
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app.handleMessage(respMsg, clientAddr, &network)
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return &respMsg, nil
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}
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app.Records = records.New()
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link, err := netlink.LinkByName(app.Config.LinkName)
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if err != nil {
|
|
return nil, fmt.Errorf("failed to find link %s: %w", app.Config.LinkName, err)
|
|
}
|
|
app.Link = link
|
|
|
|
nh4, err := netfilterHelper.New(false)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("netfilter helper init fail: %w", err)
|
|
}
|
|
app.NetfilterHelper4 = nh4
|
|
err = app.NetfilterHelper4.CleanIPTables(app.Config.ChainPrefix)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("failed to clear iptables: %w", err)
|
|
}
|
|
|
|
nh6, err := netfilterHelper.New(true)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("netfilter helper init fail: %w", err)
|
|
}
|
|
app.NetfilterHelper6 = nh6
|
|
err = app.NetfilterHelper6.CleanIPTables(app.Config.ChainPrefix)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("failed to clear iptables: %w", err)
|
|
}
|
|
|
|
for _, group := range config.Groups {
|
|
err = app.AddGroup(&group)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
|
|
return app, nil
|
|
}
|