287 lines
6.9 KiB
Go
287 lines
6.9 KiB
Go
package home
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import (
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"fmt"
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"net"
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"os"
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"strings"
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"sync"
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"time"
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"github.com/AdguardTeam/AdGuardHome/dnsfilter"
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"github.com/AdguardTeam/AdGuardHome/dnsforward"
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"github.com/AdguardTeam/dnsproxy/proxy"
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"github.com/AdguardTeam/dnsproxy/upstream"
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"github.com/AdguardTeam/golibs/log"
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"github.com/joomcode/errorx"
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"github.com/miekg/dns"
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)
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var dnsServer *dnsforward.Server
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const (
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rdnsTimeout = 3 * time.Second // max time to wait for rDNS response
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)
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type dnsContext struct {
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rdnsChannel chan string // pass data from DNS request handling thread to rDNS thread
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// contains IP addresses of clients to be resolved by rDNS
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// if IP address couldn't be resolved, it stays here forever to prevent further attempts to resolve the same IP
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rdnsIP map[string]bool
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rdnsLock sync.Mutex // synchronize access to rdnsIP
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upstream upstream.Upstream // Upstream object for our own DNS server
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}
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var dnsctx dnsContext
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// initDNSServer creates an instance of the dnsforward.Server
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// Please note that we must do it even if we don't start it
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// so that we had access to the query log and the stats
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func initDNSServer(baseDir string) {
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err := os.MkdirAll(baseDir, 0755)
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if err != nil {
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log.Fatalf("Cannot create DNS data dir at %s: %s", baseDir, err)
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}
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dnsServer = dnsforward.NewServer(baseDir)
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bindhost := config.DNS.BindHost
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if config.DNS.BindHost == "0.0.0.0" {
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bindhost = "127.0.0.1"
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}
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resolverAddress := fmt.Sprintf("%s:%d", bindhost, config.DNS.Port)
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opts := upstream.Options{
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Timeout: rdnsTimeout,
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}
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dnsctx.upstream, err = upstream.AddressToUpstream(resolverAddress, opts)
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if err != nil {
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log.Error("upstream.AddressToUpstream: %s", err)
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return
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}
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dnsctx.rdnsIP = make(map[string]bool)
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dnsctx.rdnsChannel = make(chan string, 256)
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go asyncRDNSLoop()
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}
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func isRunning() bool {
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return dnsServer != nil && dnsServer.IsRunning()
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}
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func beginAsyncRDNS(ip string) {
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if clientExists(ip) {
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return
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}
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// add IP to rdnsIP, if not exists
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dnsctx.rdnsLock.Lock()
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defer dnsctx.rdnsLock.Unlock()
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_, ok := dnsctx.rdnsIP[ip]
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if ok {
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return
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}
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dnsctx.rdnsIP[ip] = true
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log.Tracef("Adding %s for rDNS resolve", ip)
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select {
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case dnsctx.rdnsChannel <- ip:
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//
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default:
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log.Tracef("rDNS queue is full")
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}
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}
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// Use rDNS to get hostname by IP address
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func resolveRDNS(ip string) string {
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log.Tracef("Resolving host for %s", ip)
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req := dns.Msg{}
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req.Id = dns.Id()
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req.RecursionDesired = true
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req.Question = []dns.Question{
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{
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Qtype: dns.TypePTR,
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Qclass: dns.ClassINET,
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},
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}
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var err error
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req.Question[0].Name, err = dns.ReverseAddr(ip)
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if err != nil {
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log.Debug("Error while calling dns.ReverseAddr(%s): %s", ip, err)
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return ""
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}
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resp, err := dnsctx.upstream.Exchange(&req)
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if err != nil {
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log.Error("Error while making an rDNS lookup for %s: %s", ip, err)
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return ""
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}
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if len(resp.Answer) != 1 {
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log.Debug("No answer for rDNS lookup of %s", ip)
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return ""
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}
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ptr, ok := resp.Answer[0].(*dns.PTR)
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if !ok {
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log.Error("not a PTR response for %s", ip)
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return ""
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}
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log.Tracef("PTR response for %s: %s", ip, ptr.String())
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if strings.HasSuffix(ptr.Ptr, ".") {
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ptr.Ptr = ptr.Ptr[:len(ptr.Ptr)-1]
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}
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return ptr.Ptr
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}
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// Wait for a signal and then synchronously resolve hostname by IP address
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// Add the hostname:IP pair to "Clients" array
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func asyncRDNSLoop() {
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for {
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var ip string
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ip = <-dnsctx.rdnsChannel
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host := resolveRDNS(ip)
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if len(host) == 0 {
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continue
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}
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dnsctx.rdnsLock.Lock()
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delete(dnsctx.rdnsIP, ip)
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dnsctx.rdnsLock.Unlock()
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_, _ = clientAddHost(ip, host, ClientSourceRDNS)
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}
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}
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func onDNSRequest(d *proxy.DNSContext) {
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qType := d.Req.Question[0].Qtype
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if qType != dns.TypeA && qType != dns.TypeAAAA {
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return
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}
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ip := dnsforward.GetIPString(d.Addr)
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if ip == "" {
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// This would be quite weird if we get here
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return
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}
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ipAddr := net.ParseIP(ip)
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if !ipAddr.IsLoopback() {
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beginAsyncRDNS(ip)
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}
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}
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func generateServerConfig() (dnsforward.ServerConfig, error) {
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filters := []dnsfilter.Filter{}
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userFilter := userFilter()
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filters = append(filters, dnsfilter.Filter{
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ID: userFilter.ID,
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Data: userFilter.Data,
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})
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for _, filter := range config.Filters {
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if !filter.Enabled {
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continue
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}
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filters = append(filters, dnsfilter.Filter{
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ID: filter.ID,
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FilePath: filter.Path(),
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})
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}
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newconfig := dnsforward.ServerConfig{
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UDPListenAddr: &net.UDPAddr{IP: net.ParseIP(config.DNS.BindHost), Port: config.DNS.Port},
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TCPListenAddr: &net.TCPAddr{IP: net.ParseIP(config.DNS.BindHost), Port: config.DNS.Port},
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FilteringConfig: config.DNS.FilteringConfig,
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Filters: filters,
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}
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bindhost := config.DNS.BindHost
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if config.DNS.BindHost == "0.0.0.0" {
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bindhost = "127.0.0.1"
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}
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newconfig.ResolverAddress = fmt.Sprintf("%s:%d", bindhost, config.DNS.Port)
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if config.TLS.Enabled {
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newconfig.TLSConfig = config.TLS.TLSConfig
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if config.TLS.PortDNSOverTLS != 0 {
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newconfig.TLSListenAddr = &net.TCPAddr{IP: net.ParseIP(config.DNS.BindHost), Port: config.TLS.PortDNSOverTLS}
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}
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}
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upstreamConfig, err := proxy.ParseUpstreamsConfig(config.DNS.UpstreamDNS, config.DNS.BootstrapDNS, dnsforward.DefaultTimeout)
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if err != nil {
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return newconfig, fmt.Errorf("Couldn't get upstreams configuration cause: %s", err)
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}
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newconfig.Upstreams = upstreamConfig.Upstreams
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newconfig.DomainsReservedUpstreams = upstreamConfig.DomainReservedUpstreams
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newconfig.AllServers = config.DNS.AllServers
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newconfig.FilterHandler = applyClientSettings
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newconfig.OnDNSRequest = onDNSRequest
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return newconfig, nil
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}
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// If a client has his own settings, apply them
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func applyClientSettings(clientAddr string, setts *dnsfilter.RequestFilteringSettings) {
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c, ok := clientFind(clientAddr)
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if !ok || !c.UseOwnSettings {
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return
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}
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log.Debug("Using settings for client with IP %s", clientAddr)
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setts.FilteringEnabled = c.FilteringEnabled
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setts.SafeSearchEnabled = c.SafeSearchEnabled
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setts.SafeBrowsingEnabled = c.SafeBrowsingEnabled
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setts.ParentalEnabled = c.ParentalEnabled
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}
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func startDNSServer() error {
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if isRunning() {
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return fmt.Errorf("unable to start forwarding DNS server: Already running")
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}
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newconfig, err := generateServerConfig()
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if err != nil {
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return errorx.Decorate(err, "Couldn't start forwarding DNS server")
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}
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err = dnsServer.Start(&newconfig)
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if err != nil {
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return errorx.Decorate(err, "Couldn't start forwarding DNS server")
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}
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top := dnsServer.GetStatsTop()
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for k := range top.Clients {
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beginAsyncRDNS(k)
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}
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return nil
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}
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func reconfigureDNSServer() error {
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if !isRunning() {
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return nil
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}
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config, err := generateServerConfig()
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if err != nil {
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return errorx.Decorate(err, "Couldn't start forwarding DNS server")
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}
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err = dnsServer.Reconfigure(&config)
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if err != nil {
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return errorx.Decorate(err, "Couldn't start forwarding DNS server")
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}
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return nil
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}
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func stopDNSServer() error {
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if !isRunning() {
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return nil
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}
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err := dnsServer.Stop()
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if err != nil {
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return errorx.Decorate(err, "Couldn't stop forwarding DNS server")
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}
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return nil
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}
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